Btrfs: Split the extent_map code into two parts

There is now extent_map for mapping offsets in the file to disk and
extent_io for state tracking, IO submission and extent_bufers.

The new extent_map code shifts from [start,end] pairs to [start,len], and
pushes the locking out into the caller.  This allows a few performance
optimizations and is easier to use.

A number of extent_map usage bugs were fixed, mostly with failing
to remove extent_map entries when changing the file.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

14 files changed, 3612 insertions, 3413 deletions

diff --git a/fs/btrfs/Makefile b/fs/btrfs/Makefile
index 72cc3e1..9c61609 100644
--- a/fs/btrfs/Makefile
+++ b/fs/btrfs/Makefile
@@ -5,7 +5,8 @@ obj-m  := btrfs.o
 btrfs-y := super.o ctree.o extent-tree.o print-tree.o root-tree.o dir-item.o \
 	   hash.o file-item.o inode-item.o inode-map.o disk-io.o \
 	   transaction.o bit-radix.o inode.o file.o tree-defrag.o \
-	   extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o
+	   extent_map.o sysfs.o struct-funcs.o xattr.o ordered-data.o \
+	   extent_io.o
 
 ifeq ($(CONFIG_FS_POSIX_ACL),y)
 btrfs-y += acl.o
diff --git a/fs/btrfs/btrfs_inode.h b/fs/btrfs/btrfs_inode.h
index 9fc9988..9a0647d 100644
--- a/fs/btrfs/btrfs_inode.h
+++ b/fs/btrfs/btrfs_inode.h
@@ -20,6 +20,7 @@
 #define __BTRFS_I__
 
 #include "extent_map.h"
+#include "extent_io.h"
 
 /* in memory btrfs inode */
 struct btrfs_inode {
@@ -27,6 +28,7 @@ struct btrfs_inode {
 	struct btrfs_block_group_cache *block_group;
 	struct btrfs_key location;
 	struct extent_map_tree extent_tree;
+	struct extent_io_tree io_tree;
 	struct inode vfs_inode;
 
 	u64 ordered_trans;
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index b9f2975..6c65473 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -27,6 +27,7 @@
 #include <linux/completion.h>
 #include <asm/kmap_types.h>
 #include "bit-radix.h"
+#include "extent_io.h"
 #include "extent_map.h"
 
 struct btrfs_trans_handle;
@@ -314,11 +315,11 @@ struct btrfs_fs_info {
 	struct btrfs_root *tree_root;
 	struct radix_tree_root fs_roots_radix;
 
-	struct extent_map_tree free_space_cache;
-	struct extent_map_tree block_group_cache;
-	struct extent_map_tree pinned_extents;
-	struct extent_map_tree pending_del;
-	struct extent_map_tree extent_ins;
+	struct extent_io_tree free_space_cache;
+	struct extent_io_tree block_group_cache;
+	struct extent_io_tree pinned_extents;
+	struct extent_io_tree pending_del;
+	struct extent_io_tree extent_ins;
 
 	u64 generation;
 	u64 last_trans_committed;
@@ -956,7 +957,7 @@ u32 btrfs_count_snapshots_in_path(struct btrfs_root *root,
 				  u64 first_extent);
 int btrfs_extent_post_op(struct btrfs_trans_handle *trans,
 			 struct btrfs_root *root);
-int btrfs_copy_pinned(struct btrfs_root *root, struct extent_map_tree *copy);
+int btrfs_copy_pinned(struct btrfs_root *root, struct extent_io_tree *copy);
 struct btrfs_block_group_cache *btrfs_lookup_block_group(struct
 							 btrfs_fs_info *info,
 							 u64 bytenr);
@@ -1001,7 +1002,7 @@ int btrfs_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
 		      u64 owner_objectid, u64 owner_offset, int pin);
 int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
 			       struct btrfs_root *root,
-			       struct extent_map_tree *unpin);
+			       struct extent_io_tree *unpin);
 int btrfs_inc_extent_ref(struct btrfs_trans_handle *trans,
 				struct btrfs_root *root,
 				u64 bytenr, u64 num_bytes,
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 5d1f9bc..4c4ebea 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -43,14 +43,14 @@ static int check_tree_block(struct btrfs_root *root, struct extent_buffer *buf)
 }
 #endif
 
-static struct extent_map_ops btree_extent_map_ops;
+static struct extent_io_ops btree_extent_io_ops;
 
 struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
 					    u64 bytenr, u32 blocksize)
 {
 	struct inode *btree_inode = root->fs_info->btree_inode;
 	struct extent_buffer *eb;
-	eb = find_extent_buffer(&BTRFS_I(btree_inode)->extent_tree,
+	eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
 				bytenr, blocksize, GFP_NOFS);
 	return eb;
 }
@@ -61,13 +61,13 @@ struct extent_buffer *btrfs_find_create_tree_block(struct btrfs_root *root,
 	struct inode *btree_inode = root->fs_info->btree_inode;
 	struct extent_buffer *eb;
 
-	eb = alloc_extent_buffer(&BTRFS_I(btree_inode)->extent_tree,
+	eb = alloc_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
 				 bytenr, blocksize, NULL, GFP_NOFS);
 	return eb;
 }
 
 struct extent_map *btree_get_extent(struct inode *inode, struct page *page,
-				    size_t page_offset, u64 start, u64 end,
+				    size_t page_offset, u64 start, u64 len,
 				    int create)
 {
 	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
@@ -75,7 +75,9 @@ struct extent_map *btree_get_extent(struct inode *inode, struct page *page,
 	int ret;
 
 again:
-	em = lookup_extent_mapping(em_tree, start, end);
+	spin_lock(&em_tree->lock);
+	em = lookup_extent_mapping(em_tree, start, len);
+	spin_unlock(&em_tree->lock);
 	if (em) {
 		goto out;
 	}
@@ -85,11 +87,14 @@ again:
 		goto out;
 	}
 	em->start = 0;
-	em->end = (i_size_read(inode) & ~((u64)PAGE_CACHE_SIZE -1)) - 1;
+	em->len = i_size_read(inode);
 	em->block_start = 0;
-	em->block_end = em->end;
 	em->bdev = inode->i_sb->s_bdev;
+
+	spin_lock(&em_tree->lock);
 	ret = add_extent_mapping(em_tree, em);
+	spin_unlock(&em_tree->lock);
+
 	if (ret == -EEXIST) {
 		free_extent_map(em);
 		em = NULL;
@@ -175,13 +180,13 @@ static int csum_tree_block(struct btrfs_root *root, struct extent_buffer *buf,
 
 int csum_dirty_buffer(struct btrfs_root *root, struct page *page)
 {
-	struct extent_map_tree *tree;
+	struct extent_io_tree *tree;
 	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
 	u64 found_start;
 	int found_level;
 	unsigned long len;
 	struct extent_buffer *eb;
-	tree = &BTRFS_I(page->mapping->host)->extent_tree;
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
 
 	if (page->private == EXTENT_PAGE_PRIVATE)
 		goto out;
@@ -230,16 +235,16 @@ static int btree_writepage_io_hook(struct page *page, u64 start, u64 end)
 
 static int btree_writepage(struct page *page, struct writeback_control *wbc)
 {
-	struct extent_map_tree *tree;
-	tree = &BTRFS_I(page->mapping->host)->extent_tree;
+	struct extent_io_tree *tree;
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
 	return extent_write_full_page(tree, page, btree_get_extent, wbc);
 }
 
 static int btree_writepages(struct address_space *mapping,
 			    struct writeback_control *wbc)
 {
-	struct extent_map_tree *tree;
-	tree = &BTRFS_I(mapping->host)->extent_tree;
+	struct extent_io_tree *tree;
+	tree = &BTRFS_I(mapping->host)->io_tree;
 	if (wbc->sync_mode == WB_SYNC_NONE) {
 		u64 num_dirty;
 		u64 start = 0;
@@ -264,18 +269,20 @@ static int btree_writepages(struct address_space *mapping,
 
 int btree_readpage(struct file *file, struct page *page)
 {
-	struct extent_map_tree *tree;
-	tree = &BTRFS_I(page->mapping->host)->extent_tree;
+	struct extent_io_tree *tree;
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
 	return extent_read_full_page(tree, page, btree_get_extent);
 }
 
 static int btree_releasepage(struct page *page, gfp_t unused_gfp_flags)
 {
-	struct extent_map_tree *tree;
+	struct extent_io_tree *tree;
+	struct extent_map_tree *map;
 	int ret;
 
-	tree = &BTRFS_I(page->mapping->host)->extent_tree;
-	ret = try_release_extent_mapping(tree, page);
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
+	map = &BTRFS_I(page->mapping->host)->extent_tree;
+	ret = try_release_extent_mapping(map, tree, page);
 	if (ret == 1) {
 		ClearPagePrivate(page);
 		set_page_private(page, 0);
@@ -286,8 +293,8 @@ static int btree_releasepage(struct page *page, gfp_t unused_gfp_flags)
 
 static void btree_invalidatepage(struct page *page, unsigned long offset)
 {
-	struct extent_map_tree *tree;
-	tree = &BTRFS_I(page->mapping->host)->extent_tree;
+	struct extent_io_tree *tree;
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
 	extent_invalidatepage(tree, page, offset);
 	btree_releasepage(page, GFP_NOFS);
 }
@@ -331,7 +338,7 @@ int readahead_tree_block(struct btrfs_root *root, u64 bytenr, u32 blocksize)
 	buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
 	if (!buf)
 		return 0;
-	read_extent_buffer_pages(&BTRFS_I(btree_inode)->extent_tree,
+	read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,
 				 buf, 0, 0);
 	free_extent_buffer(buf);
 	return ret;
@@ -342,40 +349,39 @@ struct extent_buffer *read_tree_block(struct btrfs_root *root, u64 bytenr,
 {
 	struct extent_buffer *buf = NULL;
 	struct inode *btree_inode = root->fs_info->btree_inode;
-	struct extent_map_tree *extent_tree;
+	struct extent_io_tree *io_tree;
 	u64 end;
 	int ret;
 
-	extent_tree = &BTRFS_I(btree_inode)->extent_tree;
+	io_tree = &BTRFS_I(btree_inode)->io_tree;
 
 	buf = btrfs_find_create_tree_block(root, bytenr, blocksize);
 	if (!buf)
 		return NULL;
-	read_extent_buffer_pages(&BTRFS_I(btree_inode)->extent_tree,
-				 buf, 0, 1);
+	read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree, buf, 0, 1);
 
 	if (buf->flags & EXTENT_CSUM)
 		return buf;
 
 	end = buf->start + PAGE_CACHE_SIZE - 1;
-	if (test_range_bit(extent_tree, buf->start, end, EXTENT_CSUM, 1)) {
+	if (test_range_bit(io_tree, buf->start, end, EXTENT_CSUM, 1)) {
 		buf->flags |= EXTENT_CSUM;
 		return buf;
 	}
 
-	lock_extent(extent_tree, buf->start, end, GFP_NOFS);
+	lock_extent(io_tree, buf->start, end, GFP_NOFS);
 
-	if (test_range_bit(extent_tree, buf->start, end, EXTENT_CSUM, 1)) {
+	if (test_range_bit(io_tree, buf->start, end, EXTENT_CSUM, 1)) {
 		buf->flags |= EXTENT_CSUM;
 		goto out_unlock;
 	}
 
 	ret = csum_tree_block(root, buf, 1);
-	set_extent_bits(extent_tree, buf->start, end, EXTENT_CSUM, GFP_NOFS);
+	set_extent_bits(io_tree, buf->start, end, EXTENT_CSUM, GFP_NOFS);
 	buf->flags |= EXTENT_CSUM;
 
 out_unlock:
-	unlock_extent(extent_tree, buf->start, end, GFP_NOFS);
+	unlock_extent(io_tree, buf->start, end, GFP_NOFS);
 	return buf;
 }
 
@@ -385,7 +391,7 @@ int clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 	struct inode *btree_inode = root->fs_info->btree_inode;
 	if (btrfs_header_generation(buf) ==
 	    root->fs_info->running_transaction->transid)
-		clear_extent_buffer_dirty(&BTRFS_I(btree_inode)->extent_tree,
+		clear_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree,
 					  buf);
 	return 0;
 }
@@ -394,7 +400,7 @@ int wait_on_tree_block_writeback(struct btrfs_root *root,
 				 struct extent_buffer *buf)
 {
 	struct inode *btree_inode = root->fs_info->btree_inode;
-	wait_on_extent_buffer_writeback(&BTRFS_I(btree_inode)->extent_tree,
+	wait_on_extent_buffer_writeback(&BTRFS_I(btree_inode)->io_tree,
 					buf);
 	return 0;
 }
@@ -659,20 +665,23 @@ struct btrfs_root *open_ctree(struct super_block *sb)
 	fs_info->btree_inode->i_nlink = 1;
 	fs_info->btree_inode->i_size = sb->s_bdev->bd_inode->i_size;
 	fs_info->btree_inode->i_mapping->a_ops = &btree_aops;
-	extent_map_tree_init(&BTRFS_I(fs_info->btree_inode)->extent_tree,
+	extent_io_tree_init(&BTRFS_I(fs_info->btree_inode)->io_tree,
 			     fs_info->btree_inode->i_mapping,
 			     GFP_NOFS);
-	BTRFS_I(fs_info->btree_inode)->extent_tree.ops = &btree_extent_map_ops;
+	extent_map_tree_init(&BTRFS_I(fs_info->btree_inode)->extent_tree,
+			     GFP_NOFS);
+
+	BTRFS_I(fs_info->btree_inode)->io_tree.ops = &btree_extent_io_ops;
 
-	extent_map_tree_init(&fs_info->free_space_cache,
+	extent_io_tree_init(&fs_info->free_space_cache,
 			     fs_info->btree_inode->i_mapping, GFP_NOFS);
-	extent_map_tree_init(&fs_info->block_group_cache,
+	extent_io_tree_init(&fs_info->block_group_cache,
 			     fs_info->btree_inode->i_mapping, GFP_NOFS);
-	extent_map_tree_init(&fs_info->pinned_extents,
+	extent_io_tree_init(&fs_info->pinned_extents,
 			     fs_info->btree_inode->i_mapping, GFP_NOFS);
-	extent_map_tree_init(&fs_info->pending_del,
+	extent_io_tree_init(&fs_info->pending_del,
 			     fs_info->btree_inode->i_mapping, GFP_NOFS);
-	extent_map_tree_init(&fs_info->extent_ins,
+	extent_io_tree_init(&fs_info->extent_ins,
 			     fs_info->btree_inode->i_mapping, GFP_NOFS);
 	fs_info->do_barriers = 1;
 	fs_info->closing = 0;
@@ -787,7 +796,7 @@ int write_ctree_super(struct btrfs_trans_handle *trans, struct btrfs_root
 
 	if (!btrfs_test_opt(root, NOBARRIER))
 		blkdev_issue_flush(sb->s_bdev, NULL);
-	set_extent_buffer_dirty(&BTRFS_I(btree_inode)->extent_tree, super);
+	set_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree, super);
 	ret = sync_page_range_nolock(btree_inode, btree_inode->i_mapping,
 				     super->start, super->len);
 	if (!btrfs_test_opt(root, NOBARRIER))
@@ -864,12 +873,12 @@ int close_ctree(struct btrfs_root *root)
 
 	filemap_write_and_wait(fs_info->btree_inode->i_mapping);
 
-	extent_map_tree_empty_lru(&fs_info->free_space_cache);
-	extent_map_tree_empty_lru(&fs_info->block_group_cache);
-	extent_map_tree_empty_lru(&fs_info->pinned_extents);
-	extent_map_tree_empty_lru(&fs_info->pending_del);
-	extent_map_tree_empty_lru(&fs_info->extent_ins);
-	extent_map_tree_empty_lru(&BTRFS_I(fs_info->btree_inode)->extent_tree);
+	extent_io_tree_empty_lru(&fs_info->free_space_cache);
+	extent_io_tree_empty_lru(&fs_info->block_group_cache);
+	extent_io_tree_empty_lru(&fs_info->pinned_extents);
+	extent_io_tree_empty_lru(&fs_info->pending_del);
+	extent_io_tree_empty_lru(&fs_info->extent_ins);
+	extent_io_tree_empty_lru(&BTRFS_I(fs_info->btree_inode)->io_tree);
 
 	truncate_inode_pages(fs_info->btree_inode->i_mapping, 0);
 
@@ -892,13 +901,13 @@ int close_ctree(struct btrfs_root *root)
 int btrfs_buffer_uptodate(struct extent_buffer *buf)
 {
 	struct inode *btree_inode = buf->first_page->mapping->host;
-	return extent_buffer_uptodate(&BTRFS_I(btree_inode)->extent_tree, buf);
+	return extent_buffer_uptodate(&BTRFS_I(btree_inode)->io_tree, buf);
 }
 
 int btrfs_set_buffer_uptodate(struct extent_buffer *buf)
 {
 	struct inode *btree_inode = buf->first_page->mapping->host;
-	return set_extent_buffer_uptodate(&BTRFS_I(btree_inode)->extent_tree,
+	return set_extent_buffer_uptodate(&BTRFS_I(btree_inode)->io_tree,
 					  buf);
 }
 
@@ -914,7 +923,7 @@ void btrfs_mark_buffer_dirty(struct extent_buffer *buf)
 			transid, root->fs_info->generation);
 		WARN_ON(1);
 	}
-	set_extent_buffer_dirty(&BTRFS_I(btree_inode)->extent_tree, buf);
+	set_extent_buffer_dirty(&BTRFS_I(btree_inode)->io_tree, buf);
 }
 
 void btrfs_throttle(struct btrfs_root *root)
@@ -941,7 +950,7 @@ void btrfs_set_buffer_defrag(struct extent_buffer *buf)
 {
 	struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
 	struct inode *btree_inode = root->fs_info->btree_inode;
-	set_extent_bits(&BTRFS_I(btree_inode)->extent_tree, buf->start,
+	set_extent_bits(&BTRFS_I(btree_inode)->io_tree, buf->start,
 			buf->start + buf->len - 1, EXTENT_DEFRAG, GFP_NOFS);
 }
 
@@ -949,7 +958,7 @@ void btrfs_set_buffer_defrag_done(struct extent_buffer *buf)
 {
 	struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
 	struct inode *btree_inode = root->fs_info->btree_inode;
-	set_extent_bits(&BTRFS_I(btree_inode)->extent_tree, buf->start,
+	set_extent_bits(&BTRFS_I(btree_inode)->io_tree, buf->start,
 			buf->start + buf->len - 1, EXTENT_DEFRAG_DONE,
 			GFP_NOFS);
 }
@@ -958,7 +967,7 @@ int btrfs_buffer_defrag(struct extent_buffer *buf)
 {
 	struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
 	struct inode *btree_inode = root->fs_info->btree_inode;
-	return test_range_bit(&BTRFS_I(btree_inode)->extent_tree,
+	return test_range_bit(&BTRFS_I(btree_inode)->io_tree,
 		     buf->start, buf->start + buf->len - 1, EXTENT_DEFRAG, 0);
 }
 
@@ -966,7 +975,7 @@ int btrfs_buffer_defrag_done(struct extent_buffer *buf)
 {
 	struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
 	struct inode *btree_inode = root->fs_info->btree_inode;
-	return test_range_bit(&BTRFS_I(btree_inode)->extent_tree,
+	return test_range_bit(&BTRFS_I(btree_inode)->io_tree,
 		     buf->start, buf->start + buf->len - 1,
 		     EXTENT_DEFRAG_DONE, 0);
 }
@@ -975,7 +984,7 @@ int btrfs_clear_buffer_defrag_done(struct extent_buffer *buf)
 {
 	struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
 	struct inode *btree_inode = root->fs_info->btree_inode;
-	return clear_extent_bits(&BTRFS_I(btree_inode)->extent_tree,
+	return clear_extent_bits(&BTRFS_I(btree_inode)->io_tree,
 		     buf->start, buf->start + buf->len - 1,
 		     EXTENT_DEFRAG_DONE, GFP_NOFS);
 }
@@ -984,7 +993,7 @@ int btrfs_clear_buffer_defrag(struct extent_buffer *buf)
 {
 	struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
 	struct inode *btree_inode = root->fs_info->btree_inode;
-	return clear_extent_bits(&BTRFS_I(btree_inode)->extent_tree,
+	return clear_extent_bits(&BTRFS_I(btree_inode)->io_tree,
 		     buf->start, buf->start + buf->len - 1,
 		     EXTENT_DEFRAG, GFP_NOFS);
 }
@@ -993,10 +1002,10 @@ int btrfs_read_buffer(struct extent_buffer *buf)
 {
 	struct btrfs_root *root = BTRFS_I(buf->first_page->mapping->host)->root;
 	struct inode *btree_inode = root->fs_info->btree_inode;
-	return read_extent_buffer_pages(&BTRFS_I(btree_inode)->extent_tree,
+	return read_extent_buffer_pages(&BTRFS_I(btree_inode)->io_tree,
 					buf, 0, 1);
 }
 
-static struct extent_map_ops btree_extent_map_ops = {
+static struct extent_io_ops btree_extent_io_ops = {
 	.writepage_io_hook = btree_writepage_io_hook,
 };
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index b69a466..1cf125a 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -63,7 +63,7 @@ static int cache_block_group(struct btrfs_root *root,
 	int ret;
 	struct btrfs_key key;
 	struct extent_buffer *leaf;
-	struct extent_map_tree *free_space_cache;
+	struct extent_io_tree *free_space_cache;
 	int slot;
 	u64 last = 0;
 	u64 hole_size;
@@ -158,7 +158,7 @@ struct btrfs_block_group_cache *btrfs_lookup_block_group(struct
 							 btrfs_fs_info *info,
 							 u64 bytenr)
 {
-	struct extent_map_tree *block_group_cache;
+	struct extent_io_tree *block_group_cache;
 	struct btrfs_block_group_cache *block_group = NULL;
 	u64 ptr;
 	u64 start;
@@ -281,7 +281,7 @@ struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
 						 int data, int owner)
 {
 	struct btrfs_block_group_cache *cache;
-	struct extent_map_tree *block_group_cache;
+	struct extent_io_tree *block_group_cache;
 	struct btrfs_block_group_cache *found_group = NULL;
 	struct btrfs_fs_info *info = root->fs_info;
 	u64 used;
@@ -951,7 +951,7 @@ fail:
 int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
 				   struct btrfs_root *root)
 {
-	struct extent_map_tree *block_group_cache;
+	struct extent_io_tree *block_group_cache;
 	struct btrfs_block_group_cache *cache;
 	int ret;
 	int err = 0;
@@ -1107,12 +1107,12 @@ static int update_pinned_extents(struct btrfs_root *root,
 	return 0;
 }
 
-int btrfs_copy_pinned(struct btrfs_root *root, struct extent_map_tree *copy)
+int btrfs_copy_pinned(struct btrfs_root *root, struct extent_io_tree *copy)
 {
 	u64 last = 0;
 	u64 start;
 	u64 end;
-	struct extent_map_tree *pinned_extents = &root->fs_info->pinned_extents;
+	struct extent_io_tree *pinned_extents = &root->fs_info->pinned_extents;
 	int ret;
 
 	while(1) {
@@ -1128,12 +1128,12 @@ int btrfs_copy_pinned(struct btrfs_root *root, struct extent_map_tree *copy)
 
 int btrfs_finish_extent_commit(struct btrfs_trans_handle *trans,
 			       struct btrfs_root *root,
-			       struct extent_map_tree *unpin)
+			       struct extent_io_tree *unpin)
 {
 	u64 start;
 	u64 end;
 	int ret;
-	struct extent_map_tree *free_space_cache;
+	struct extent_io_tree *free_space_cache;
 	free_space_cache = &root->fs_info->free_space_cache;
 
 	while(1) {
@@ -1329,8 +1329,8 @@ static int del_pending_extents(struct btrfs_trans_handle *trans, struct
 	int err = 0;
 	u64 start;
 	u64 end;
-	struct extent_map_tree *pending_del;
-	struct extent_map_tree *pinned_extents;
+	struct extent_io_tree *pending_del;
+	struct extent_io_tree *pinned_extents;
 
 	pending_del = &extent_root->fs_info->pending_del;
 	pinned_extents = &extent_root->fs_info->pinned_extents;
@@ -1802,7 +1802,7 @@ struct extent_buffer *__btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
 
 	set_extent_dirty(&trans->transaction->dirty_pages, buf->start,
 			 buf->start + buf->len - 1, GFP_NOFS);
-	set_extent_bits(&BTRFS_I(root->fs_info->btree_inode)->extent_tree,
+	set_extent_bits(&BTRFS_I(root->fs_info->btree_inode)->io_tree,
 			buf->start, buf->start + buf->len - 1,
 			EXTENT_CSUM, GFP_NOFS);
 	buf->flags |= EXTENT_CSUM;
@@ -2166,7 +2166,7 @@ static int noinline relocate_inode_pages(struct inode *inode, u64 start,
 	unsigned long i;
 	struct page *page;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
-	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	struct file_ra_state *ra;
 
 	ra = kzalloc(sizeof(*ra), GFP_NOFS);
@@ -2195,15 +2195,14 @@ static int noinline relocate_inode_pages(struct inode *inode, u64 start,
 		page_start = (u64)page->index << PAGE_CACHE_SHIFT;
 		page_end = page_start + PAGE_CACHE_SIZE - 1;
 
-		lock_extent(em_tree, page_start, page_end, GFP_NOFS);
+		lock_extent(io_tree, page_start, page_end, GFP_NOFS);
 
 		delalloc_start = page_start;
-		existing_delalloc =
-			count_range_bits(&BTRFS_I(inode)->extent_tree,
-					 &delalloc_start, page_end,
-					 PAGE_CACHE_SIZE, EXTENT_DELALLOC);
+		existing_delalloc = count_range_bits(io_tree,
+					     &delalloc_start, page_end,
+					     PAGE_CACHE_SIZE, EXTENT_DELALLOC);
 
-		set_extent_delalloc(em_tree, page_start,
+		set_extent_delalloc(io_tree, page_start,
 				    page_end, GFP_NOFS);
 
 		spin_lock(&root->fs_info->delalloc_lock);
@@ -2211,7 +2210,7 @@ static int noinline relocate_inode_pages(struct inode *inode, u64 start,
 						 existing_delalloc;
 		spin_unlock(&root->fs_info->delalloc_lock);
 
-		unlock_extent(em_tree, page_start, page_end, GFP_NOFS);
+		unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
 		set_page_dirty(page);
 		unlock_page(page);
 		page_cache_release(page);
@@ -2379,7 +2378,7 @@ int btrfs_shrink_extent_tree(struct btrfs_root *root, u64 new_size)
 	u64 cur_byte;
 	u64 total_found;
 	struct btrfs_fs_info *info = root->fs_info;
-	struct extent_map_tree *block_group_cache;
+	struct extent_io_tree *block_group_cache;
 	struct btrfs_key key;
 	struct btrfs_key found_key;
 	struct extent_buffer *leaf;
@@ -2561,7 +2560,7 @@ int btrfs_grow_extent_tree(struct btrfs_trans_handle *trans,
 	struct btrfs_block_group_cache *cache;
 	struct btrfs_block_group_item *item;
 	struct btrfs_fs_info *info = root->fs_info;
-	struct extent_map_tree *block_group_cache;
+	struct extent_io_tree *block_group_cache;
 	struct btrfs_key key;
 	struct extent_buffer *leaf;
 	int ret;
@@ -2645,7 +2644,7 @@ int btrfs_read_block_groups(struct btrfs_root *root)
 	int bit;
 	struct btrfs_block_group_cache *cache;
 	struct btrfs_fs_info *info = root->fs_info;
-	struct extent_map_tree *block_group_cache;
+	struct extent_io_tree *block_group_cache;
 	struct btrfs_key key;
 	struct btrfs_key found_key;
 	struct extent_buffer *leaf;
diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
new file mode 100644
index 0000000..15cc158
--- /dev/null
+++ b/fs/btrfs/extent_io.c
@@ -0,0 +1,3089 @@
+#include <linux/bitops.h>
+#include <linux/slab.h>
+#include <linux/bio.h>
+#include <linux/mm.h>
+#include <linux/gfp.h>
+#include <linux/pagemap.h>
+#include <linux/page-flags.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/blkdev.h>
+#include <linux/swap.h>
+#include <linux/version.h>
+#include <linux/writeback.h>
+#include <linux/pagevec.h>
+#include "extent_io.h"
+#include "extent_map.h"
+
+/* temporary define until extent_map moves out of btrfs */
+struct kmem_cache *btrfs_cache_create(const char *name, size_t size,
+				       unsigned long extra_flags,
+				       void (*ctor)(void *, struct kmem_cache *,
+						    unsigned long));
+
+static struct kmem_cache *extent_state_cache;
+static struct kmem_cache *extent_buffer_cache;
+
+static LIST_HEAD(buffers);
+static LIST_HEAD(states);
+
+static spinlock_t state_lock = SPIN_LOCK_UNLOCKED;
+#define BUFFER_LRU_MAX 64
+
+struct tree_entry {
+	u64 start;
+	u64 end;
+	int in_tree;
+	struct rb_node rb_node;
+};
+
+struct extent_page_data {
+	struct bio *bio;
+	struct extent_io_tree *tree;
+	get_extent_t *get_extent;
+};
+
+int __init extent_io_init(void)
+{
+	extent_state_cache = btrfs_cache_create("extent_state",
+					    sizeof(struct extent_state), 0,
+					    NULL);
+	if (!extent_state_cache)
+		return -ENOMEM;
+
+	extent_buffer_cache = btrfs_cache_create("extent_buffers",
+					    sizeof(struct extent_buffer), 0,
+					    NULL);
+	if (!extent_buffer_cache)
+		goto free_state_cache;
+	return 0;
+
+free_state_cache:
+	kmem_cache_destroy(extent_state_cache);
+	return -ENOMEM;
+}
+
+void extent_io_exit(void)
+{
+	struct extent_state *state;
+
+	while (!list_empty(&states)) {
+		state = list_entry(states.next, struct extent_state, list);
+		printk("state leak: start %Lu end %Lu state %lu in tree %d refs %d\n", state->start, state->end, state->state, state->in_tree, atomic_read(&state->refs));
+		list_del(&state->list);
+		kmem_cache_free(extent_state_cache, state);
+
+	}
+
+	if (extent_state_cache)
+		kmem_cache_destroy(extent_state_cache);
+	if (extent_buffer_cache)
+		kmem_cache_destroy(extent_buffer_cache);
+}
+
+void extent_io_tree_init(struct extent_io_tree *tree,
+			  struct address_space *mapping, gfp_t mask)
+{
+	tree->state.rb_node = NULL;
+	tree->ops = NULL;
+	tree->dirty_bytes = 0;
+	rwlock_init(&tree->lock);
+	spin_lock_init(&tree->lru_lock);
+	tree->mapping = mapping;
+	INIT_LIST_HEAD(&tree->buffer_lru);
+	tree->lru_size = 0;
+}
+EXPORT_SYMBOL(extent_io_tree_init);
+
+void extent_io_tree_empty_lru(struct extent_io_tree *tree)
+{
+	struct extent_buffer *eb;
+	while(!list_empty(&tree->buffer_lru)) {
+		eb = list_entry(tree->buffer_lru.next, struct extent_buffer,
+				lru);
+		list_del_init(&eb->lru);
+		free_extent_buffer(eb);
+	}
+}
+EXPORT_SYMBOL(extent_io_tree_empty_lru);
+
+struct extent_state *alloc_extent_state(gfp_t mask)
+{
+	struct extent_state *state;
+	unsigned long flags;
+
+	state = kmem_cache_alloc(extent_state_cache, mask);
+	if (!state || IS_ERR(state))
+		return state;
+	state->state = 0;
+	state->in_tree = 0;
+	state->private = 0;
+
+	spin_lock_irqsave(&state_lock, flags);
+	list_add(&state->list, &states);
+	spin_unlock_irqrestore(&state_lock, flags);
+
+	atomic_set(&state->refs, 1);
+	init_waitqueue_head(&state->wq);
+	return state;
+}
+EXPORT_SYMBOL(alloc_extent_state);
+
+void free_extent_state(struct extent_state *state)
+{
+	unsigned long flags;
+	if (!state)
+		return;
+	if (atomic_dec_and_test(&state->refs)) {
+		WARN_ON(state->in_tree);
+		spin_lock_irqsave(&state_lock, flags);
+		list_del(&state->list);
+		spin_unlock_irqrestore(&state_lock, flags);
+		kmem_cache_free(extent_state_cache, state);
+	}
+}
+EXPORT_SYMBOL(free_extent_state);
+
+static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
+				   struct rb_node *node)
+{
+	struct rb_node ** p = &root->rb_node;
+	struct rb_node * parent = NULL;
+	struct tree_entry *entry;
+
+	while(*p) {
+		parent = *p;
+		entry = rb_entry(parent, struct tree_entry, rb_node);
+
+		if (offset < entry->start)
+			p = &(*p)->rb_left;
+		else if (offset > entry->end)
+			p = &(*p)->rb_right;
+		else
+			return parent;
+	}
+
+	entry = rb_entry(node, struct tree_entry, rb_node);
+	entry->in_tree = 1;
+	rb_link_node(node, parent, p);
+	rb_insert_color(node, root);
+	return NULL;
+}
+
+static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
+				     struct rb_node **prev_ret,
+				     struct rb_node **next_ret)
+{
+	struct rb_node * n = root->rb_node;
+	struct rb_node *prev = NULL;
+	struct rb_node *orig_prev = NULL;
+	struct tree_entry *entry;
+	struct tree_entry *prev_entry = NULL;
+
+	while(n) {
+		entry = rb_entry(n, struct tree_entry, rb_node);
+		prev = n;
+		prev_entry = entry;
+
+		if (offset < entry->start)
+			n = n->rb_left;
+		else if (offset > entry->end)
+			n = n->rb_right;
+		else
+			return n;
+	}
+
+	if (prev_ret) {
+		orig_prev = prev;
+		while(prev && offset > prev_entry->end) {
+			prev = rb_next(prev);
+			prev_entry = rb_entry(prev, struct tree_entry, rb_node);
+		}
+		*prev_ret = prev;
+		prev = orig_prev;
+	}
+
+	if (next_ret) {
+		prev_entry = rb_entry(prev, struct tree_entry, rb_node);
+		while(prev && offset < prev_entry->start) {
+			prev = rb_prev(prev);
+			prev_entry = rb_entry(prev, struct tree_entry, rb_node);
+		}
+		*next_ret = prev;
+	}
+	return NULL;
+}
+
+static inline struct rb_node *tree_search(struct rb_root *root, u64 offset)
+{
+	struct rb_node *prev;
+	struct rb_node *ret;
+	ret = __tree_search(root, offset, &prev, NULL);
+	if (!ret)
+		return prev;
+	return ret;
+}
+
+/*
+ * utility function to look for merge candidates inside a given range.
+ * Any extents with matching state are merged together into a single
+ * extent in the tree.  Extents with EXTENT_IO in their state field
+ * are not merged because the end_io handlers need to be able to do
+ * operations on them without sleeping (or doing allocations/splits).
+ *
+ * This should be called with the tree lock held.
+ */
+static int merge_state(struct extent_io_tree *tree,
+		       struct extent_state *state)
+{
+	struct extent_state *other;
+	struct rb_node *other_node;
+
+	if (state->state & EXTENT_IOBITS)
+		return 0;
+
+	other_node = rb_prev(&state->rb_node);
+	if (other_node) {
+		other = rb_entry(other_node, struct extent_state, rb_node);
+		if (other->end == state->start - 1 &&
+		    other->state == state->state) {
+			state->start = other->start;
+			other->in_tree = 0;
+			rb_erase(&other->rb_node, &tree->state);
+			free_extent_state(other);
+		}
+	}
+	other_node = rb_next(&state->rb_node);
+	if (other_node) {
+		other = rb_entry(other_node, struct extent_state, rb_node);
+		if (other->start == state->end + 1 &&
+		    other->state == state->state) {
+			other->start = state->start;
+			state->in_tree = 0;
+			rb_erase(&state->rb_node, &tree->state);
+			free_extent_state(state);
+		}
+	}
+	return 0;
+}
+
+/*
+ * insert an extent_state struct into the tree.  'bits' are set on the
+ * struct before it is inserted.
+ *
+ * This may return -EEXIST if the extent is already there, in which case the
+ * state struct is freed.
+ *
+ * The tree lock is not taken internally.  This is a utility function and
+ * probably isn't what you want to call (see set/clear_extent_bit).
+ */
+static int insert_state(struct extent_io_tree *tree,
+			struct extent_state *state, u64 start, u64 end,
+			int bits)
+{
+	struct rb_node *node;
+
+	if (end < start) {
+		printk("end < start %Lu %Lu\n", end, start);
+		WARN_ON(1);
+	}
+	if (bits & EXTENT_DIRTY)
+		tree->dirty_bytes += end - start + 1;
+	state->state |= bits;
+	state->start = start;
+	state->end = end;
+	node = tree_insert(&tree->state, end, &state->rb_node);
+	if (node) {
+		struct extent_state *found;
+		found = rb_entry(node, struct extent_state, rb_node);
+		printk("found node %Lu %Lu on insert of %Lu %Lu\n", found->start, found->end, start, end);
+		free_extent_state(state);
+		return -EEXIST;
+	}
+	merge_state(tree, state);
+	return 0;
+}
+
+/*
+ * split a given extent state struct in two, inserting the preallocated
+ * struct 'prealloc' as the newly created second half.  'split' indicates an
+ * offset inside 'orig' where it should be split.
+ *
+ * Before calling,
+ * the tree has 'orig' at [orig->start, orig->end].  After calling, there
+ * are two extent state structs in the tree:
+ * prealloc: [orig->start, split - 1]
+ * orig: [ split, orig->end ]
+ *
+ * The tree locks are not taken by this function. They need to be held
+ * by the caller.
+ */
+static int split_state(struct extent_io_tree *tree, struct extent_state *orig,
+		       struct extent_state *prealloc, u64 split)
+{
+	struct rb_node *node;
+	prealloc->start = orig->start;
+	prealloc->end = split - 1;
+	prealloc->state = orig->state;
+	orig->start = split;
+
+	node = tree_insert(&tree->state, prealloc->end, &prealloc->rb_node);
+	if (node) {
+		struct extent_state *found;
+		found = rb_entry(node, struct extent_state, rb_node);
+		printk("found node %Lu %Lu on insert of %Lu %Lu\n", found->start, found->end, prealloc->start, prealloc->end);
+		free_extent_state(prealloc);
+		return -EEXIST;
+	}
+	return 0;
+}
+
+/*
+ * utility function to clear some bits in an extent state struct.
+ * it will optionally wake up any one waiting on this state (wake == 1), or
+ * forcibly remove the state from the tree (delete == 1).
+ *
+ * If no bits are set on the state struct after clearing things, the
+ * struct is freed and removed from the tree
+ */
+static int clear_state_bit(struct extent_io_tree *tree,
+			    struct extent_state *state, int bits, int wake,
+			    int delete)
+{
+	int ret = state->state & bits;
+
+	if ((bits & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
+		u64 range = state->end - state->start + 1;
+		WARN_ON(range > tree->dirty_bytes);
+		tree->dirty_bytes -= range;
+	}
+	state->state &= ~bits;
+	if (wake)
+		wake_up(&state->wq);
+	if (delete || state->state == 0) {
+		if (state->in_tree) {
+			rb_erase(&state->rb_node, &tree->state);
+			state->in_tree = 0;
+			free_extent_state(state);
+		} else {
+			WARN_ON(1);
+		}
+	} else {
+		merge_state(tree, state);
+	}
+	return ret;
+}
+
+/*
+ * clear some bits on a range in the tree.  This may require splitting
+ * or inserting elements in the tree, so the gfp mask is used to
+ * indicate which allocations or sleeping are allowed.
+ *
+ * pass 'wake' == 1 to kick any sleepers, and 'delete' == 1 to remove
+ * the given range from the tree regardless of state (ie for truncate).
+ *
+ * the range [start, end] is inclusive.
+ *
+ * This takes the tree lock, and returns < 0 on error, > 0 if any of the
+ * bits were already set, or zero if none of the bits were already set.
+ */
+int clear_extent_bit(struct extent_io_tree *tree, u64 start, u64 end,
+		     int bits, int wake, int delete, gfp_t mask)
+{
+	struct extent_state *state;
+	struct extent_state *prealloc = NULL;
+	struct rb_node *node;
+	unsigned long flags;
+	int err;
+	int set = 0;
+
+again:
+	if (!prealloc && (mask & __GFP_WAIT)) {
+		prealloc = alloc_extent_state(mask);
+		if (!prealloc)
+			return -ENOMEM;
+	}
+
+	write_lock_irqsave(&tree->lock, flags);
+	/*
+	 * this search will find the extents that end after
+	 * our range starts
+	 */
+	node = tree_search(&tree->state, start);
+	if (!node)
+		goto out;
+	state = rb_entry(node, struct extent_state, rb_node);
+	if (state->start > end)
+		goto out;
+	WARN_ON(state->end < start);
+
+	/*
+	 *     | ---- desired range ---- |
+	 *  | state | or
+	 *  | ------------- state -------------- |
+	 *
+	 * We need to split the extent we found, and may flip
+	 * bits on second half.
+	 *
+	 * If the extent we found extends past our range, we
+	 * just split and search again.  It'll get split again
+	 * the next time though.
+	 *
+	 * If the extent we found is inside our range, we clear
+	 * the desired bit on it.
+	 */
+
+	if (state->start < start) {
+		err = split_state(tree, state, prealloc, start);
+		BUG_ON(err == -EEXIST);
+		prealloc = NULL;
+		if (err)
+			goto out;
+		if (state->end <= end) {
+			start = state->end + 1;
+			set |= clear_state_bit(tree, state, bits,
+					wake, delete);
+		} else {
+			start = state->start;
+		}
+		goto search_again;
+	}
+	/*
+	 * | ---- desired range ---- |
+	 *                        | state |
+	 * We need to split the extent, and clear the bit
+	 * on the first half
+	 */
+	if (state->start <= end && state->end > end) {
+		err = split_state(tree, state, prealloc, end + 1);
+		BUG_ON(err == -EEXIST);
+
+		if (wake)
+			wake_up(&state->wq);
+		set |= clear_state_bit(tree, prealloc, bits,
+				       wake, delete);
+		prealloc = NULL;
+		goto out;
+	}
+
+	start = state->end + 1;
+	set |= clear_state_bit(tree, state, bits, wake, delete);
+	goto search_again;
+
+out:
+	write_unlock_irqrestore(&tree->lock, flags);
+	if (prealloc)
+		free_extent_state(prealloc);
+
+	return set;
+
+search_again:
+	if (start > end)
+		goto out;
+	write_unlock_irqrestore(&tree->lock, flags);
+	if (mask & __GFP_WAIT)
+		cond_resched();
+	goto again;
+}
+EXPORT_SYMBOL(clear_extent_bit);
+
+static int wait_on_state(struct extent_io_tree *tree,
+			 struct extent_state *state)
+{
+	DEFINE_WAIT(wait);
+	prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE);
+	read_unlock_irq(&tree->lock);
+	schedule();
+	read_lock_irq(&tree->lock);
+	finish_wait(&state->wq, &wait);
+	return 0;
+}
+
+/*
+ * waits for one or more bits to clear on a range in the state tree.
+ * The range [start, end] is inclusive.
+ * The tree lock is taken by this function
+ */
+int wait_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, int bits)
+{
+	struct extent_state *state;
+	struct rb_node *node;
+
+	read_lock_irq(&tree->lock);
+again:
+	while (1) {
+		/*
+		 * this search will find all the extents that end after
+		 * our range starts
+		 */
+		node = tree_search(&tree->state, start);
+		if (!node)
+			break;
+
+		state = rb_entry(node, struct extent_state, rb_node);
+
+		if (state->start > end)
+			goto out;
+
+		if (state->state & bits) {
+			start = state->start;
+			atomic_inc(&state->refs);
+			wait_on_state(tree, state);
+			free_extent_state(state);
+			goto again;
+		}
+		start = state->end + 1;
+
+		if (start > end)
+			break;
+
+		if (need_resched()) {
+			read_unlock_irq(&tree->lock);
+			cond_resched();
+			read_lock_irq(&tree->lock);
+		}
+	}
+out:
+	read_unlock_irq(&tree->lock);
+	return 0;
+}
+EXPORT_SYMBOL(wait_extent_bit);
+
+static void set_state_bits(struct extent_io_tree *tree,
+			   struct extent_state *state,
+			   int bits)
+{
+	if ((bits & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) {
+		u64 range = state->end - state->start + 1;
+		tree->dirty_bytes += range;
+	}
+	state->state |= bits;
+}
+
+/*
+ * set some bits on a range in the tree.  This may require allocations
+ * or sleeping, so the gfp mask is used to indicate what is allowed.
+ *
+ * If 'exclusive' == 1, this will fail with -EEXIST if some part of the
+ * range already has the desired bits set.  The start of the existing
+ * range is returned in failed_start in this case.
+ *
+ * [start, end] is inclusive
+ * This takes the tree lock.
+ */
+int set_extent_bit(struct extent_io_tree *tree, u64 start, u64 end, int bits,
+		   int exclusive, u64 *failed_start, gfp_t mask)
+{
+	struct extent_state *state;
+	struct extent_state *prealloc = NULL;
+	struct rb_node *node;
+	unsigned long flags;
+	int err = 0;
+	int set;
+	u64 last_start;
+	u64 last_end;
+again:
+	if (!prealloc && (mask & __GFP_WAIT)) {
+		prealloc = alloc_extent_state(mask);
+		if (!prealloc)
+			return -ENOMEM;
+	}
+
+	write_lock_irqsave(&tree->lock, flags);
+	/*
+	 * this search will find all the extents that end after
+	 * our range starts.
+	 */
+	node = tree_search(&tree->state, start);
+	if (!node) {
+		err = insert_state(tree, prealloc, start, end, bits);
+		prealloc = NULL;
+		BUG_ON(err == -EEXIST);
+		goto out;
+	}
+
+	state = rb_entry(node, struct extent_state, rb_node);
+	last_start = state->start;
+	last_end = state->end;
+
+	/*
+	 * | ---- desired range ---- |
+	 * | state |
+	 *
+	 * Just lock what we found and keep going
+	 */
+	if (state->start == start && state->end <= end) {
+		set = state->state & bits;
+		if (set && exclusive) {
+			*failed_start = state->start;
+			err = -EEXIST;
+			goto out;
+		}
+		set_state_bits(tree, state, bits);
+		start = state->end + 1;
+		merge_state(tree, state);
+		goto search_again;
+	}
+
+	/*
+	 *     | ---- desired range ---- |
+	 * | state |
+	 *   or
+	 * | ------------- state -------------- |
+	 *
+	 * We need to split the extent we found, and may flip bits on
+	 * second half.
+	 *
+	 * If the extent we found extends past our
+	 * range, we just split and search again.  It'll get split
+	 * again the next time though.
+	 *
+	 * If the extent we found is inside our range, we set the
+	 * desired bit on it.
+	 */
+	if (state->start < start) {
+		set = state->state & bits;
+		if (exclusive && set) {
+			*failed_start = start;
+			err = -EEXIST;
+			goto out;
+		}
+		err = split_state(tree, state, prealloc, start);
+		BUG_ON(err == -EEXIST);
+		prealloc = NULL;
+		if (err)
+			goto out;
+		if (state->end <= end) {
+			set_state_bits(tree, state, bits);
+			start = state->end + 1;
+			merge_state(tree, state);
+		} else {
+			start = state->start;
+		}
+		goto search_again;
+	}
+	/*
+	 * | ---- desired range ---- |
+	 *     | state | or               | state |
+	 *
+	 * There's a hole, we need to insert something in it and
+	 * ignore the extent we found.
+	 */
+	if (state->start > start) {
+		u64 this_end;
+		if (end < last_start)
+			this_end = end;
+		else
+			this_end = last_start -1;
+		err = insert_state(tree, prealloc, start, this_end,
+				   bits);
+		prealloc = NULL;
+		BUG_ON(err == -EEXIST);
+		if (err)
+			goto out;
+		start = this_end + 1;
+		goto search_again;
+	}
+	/*
+	 * | ---- desired range ---- |
+	 *                        | state |
+	 * We need to split the extent, and set the bit
+	 * on the first half
+	 */
+	if (state->start <= end && state->end > end) {
+		set = state->state & bits;
+		if (exclusive && set) {
+			*failed_start = start;
+			err = -EEXIST;
+			goto out;
+		}
+		err = split_state(tree, state, prealloc, end + 1);
+		BUG_ON(err == -EEXIST);
+
+		set_state_bits(tree, prealloc, bits);
+		merge_state(tree, prealloc);
+		prealloc = NULL;
+		goto out;
+	}
+
+	goto search_again;
+
+out:
+	write_unlock_irqrestore(&tree->lock, flags);
+	if (prealloc)
+		free_extent_state(prealloc);
+
+	return err;
+
+search_again:
+	if (start > end)
+		goto out;
+	write_unlock_irqrestore(&tree->lock, flags);
+	if (mask & __GFP_WAIT)
+		cond_resched();
+	goto again;
+}
+EXPORT_SYMBOL(set_extent_bit);
+
+/* wrappers around set/clear extent bit */
+int set_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
+		     gfp_t mask)
+{
+	return set_extent_bit(tree, start, end, EXTENT_DIRTY, 0, NULL,
+			      mask);
+}
+EXPORT_SYMBOL(set_extent_dirty);
+
+int set_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
+		    int bits, gfp_t mask)
+{
+	return set_extent_bit(tree, start, end, bits, 0, NULL,
+			      mask);
+}
+EXPORT_SYMBOL(set_extent_bits);
+
+int clear_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
+		      int bits, gfp_t mask)
+{
+	return clear_extent_bit(tree, start, end, bits, 0, 0, mask);
+}
+EXPORT_SYMBOL(clear_extent_bits);
+
+int set_extent_delalloc(struct extent_io_tree *tree, u64 start, u64 end,
+		     gfp_t mask)
+{
+	return set_extent_bit(tree, start, end,
+			      EXTENT_DELALLOC | EXTENT_DIRTY, 0, NULL,
+			      mask);
+}
+EXPORT_SYMBOL(set_extent_delalloc);
+
+int clear_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
+		       gfp_t mask)
+{
+	return clear_extent_bit(tree, start, end,
+				EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, mask);
+}
+EXPORT_SYMBOL(clear_extent_dirty);
+
+int set_extent_new(struct extent_io_tree *tree, u64 start, u64 end,
+		     gfp_t mask)
+{
+	return set_extent_bit(tree, start, end, EXTENT_NEW, 0, NULL,
+			      mask);
+}
+EXPORT_SYMBOL(set_extent_new);
+
+int clear_extent_new(struct extent_io_tree *tree, u64 start, u64 end,
+		       gfp_t mask)
+{
+	return clear_extent_bit(tree, start, end, EXTENT_NEW, 0, 0, mask);
+}
+EXPORT_SYMBOL(clear_extent_new);
+
+int set_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end,
+			gfp_t mask)
+{
+	return set_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, NULL,
+			      mask);
+}
+EXPORT_SYMBOL(set_extent_uptodate);
+
+int clear_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end,
+			  gfp_t mask)
+{
+	return clear_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, 0, mask);
+}
+EXPORT_SYMBOL(clear_extent_uptodate);
+
+int set_extent_writeback(struct extent_io_tree *tree, u64 start, u64 end,
+			 gfp_t mask)
+{
+	return set_extent_bit(tree, start, end, EXTENT_WRITEBACK,
+			      0, NULL, mask);
+}
+EXPORT_SYMBOL(set_extent_writeback);
+
+int clear_extent_writeback(struct extent_io_tree *tree, u64 start, u64 end,
+			   gfp_t mask)
+{
+	return clear_extent_bit(tree, start, end, EXTENT_WRITEBACK, 1, 0, mask);
+}
+EXPORT_SYMBOL(clear_extent_writeback);
+
+int wait_on_extent_writeback(struct extent_io_tree *tree, u64 start, u64 end)
+{
+	return wait_extent_bit(tree, start, end, EXTENT_WRITEBACK);
+}
+EXPORT_SYMBOL(wait_on_extent_writeback);
+
+/*
+ * locks a range in ascending order, waiting for any locked regions
+ * it hits on the way.  [start,end] are inclusive, and this will sleep.
+ */
+int lock_extent(struct extent_io_tree *tree, u64 start, u64 end, gfp_t mask)
+{
+	int err;
+	u64 failed_start;
+	while (1) {
+		err = set_extent_bit(tree, start, end, EXTENT_LOCKED, 1,
+				     &failed_start, mask);
+		if (err == -EEXIST && (mask & __GFP_WAIT)) {
+			wait_extent_bit(tree, failed_start, end, EXTENT_LOCKED);
+			start = failed_start;
+		} else {
+			break;
+		}
+		WARN_ON(start > end);
+	}
+	return err;
+}
+EXPORT_SYMBOL(lock_extent);
+
+int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end,
+		  gfp_t mask)
+{
+	return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, mask);
+}
+EXPORT_SYMBOL(unlock_extent);
+
+/*
+ * helper function to set pages and extents in the tree dirty
+ */
+int set_range_dirty(struct extent_io_tree *tree, u64 start, u64 end)
+{
+	unsigned long index = start >> PAGE_CACHE_SHIFT;
+	unsigned long end_index = end >> PAGE_CACHE_SHIFT;
+	struct page *page;
+
+	while (index <= end_index) {
+		page = find_get_page(tree->mapping, index);
+		BUG_ON(!page);
+		__set_page_dirty_nobuffers(page);
+		page_cache_release(page);
+		index++;
+	}
+	set_extent_dirty(tree, start, end, GFP_NOFS);
+	return 0;
+}
+EXPORT_SYMBOL(set_range_dirty);
+
+/*
+ * helper function to set both pages and extents in the tree writeback
+ */
+int set_range_writeback(struct extent_io_tree *tree, u64 start, u64 end)
+{
+	unsigned long index = start >> PAGE_CACHE_SHIFT;
+	unsigned long end_index = end >> PAGE_CACHE_SHIFT;
+	struct page *page;
+
+	while (index <= end_index) {
+		page = find_get_page(tree->mapping, index);
+		BUG_ON(!page);
+		set_page_writeback(page);
+		page_cache_release(page);
+		index++;
+	}
+	set_extent_writeback(tree, start, end, GFP_NOFS);
+	return 0;
+}
+EXPORT_SYMBOL(set_range_writeback);
+
+int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
+			  u64 *start_ret, u64 *end_ret, int bits)
+{
+	struct rb_node *node;
+	struct extent_state *state;
+	int ret = 1;
+
+	read_lock_irq(&tree->lock);
+	/*
+	 * this search will find all the extents that end after
+	 * our range starts.
+	 */
+	node = tree_search(&tree->state, start);
+	if (!node || IS_ERR(node)) {
+		goto out;
+	}
+
+	while(1) {
+		state = rb_entry(node, struct extent_state, rb_node);
+		if (state->end >= start && (state->state & bits)) {
+			*start_ret = state->start;
+			*end_ret = state->end;
+			ret = 0;
+			break;
+		}
+		node = rb_next(node);
+		if (!node)
+			break;
+	}
+out:
+	read_unlock_irq(&tree->lock);
+	return ret;
+}
+EXPORT_SYMBOL(find_first_extent_bit);
+
+u64 find_lock_delalloc_range(struct extent_io_tree *tree,
+			     u64 *start, u64 *end, u64 max_bytes)
+{
+	struct rb_node *node;
+	struct extent_state *state;
+	u64 cur_start = *start;
+	u64 found = 0;
+	u64 total_bytes = 0;
+
+	write_lock_irq(&tree->lock);
+	/*
+	 * this search will find all the extents that end after
+	 * our range starts.
+	 */
+search_again:
+	node = tree_search(&tree->state, cur_start);
+	if (!node || IS_ERR(node)) {
+		*end = (u64)-1;
+		goto out;
+	}
+
+	while(1) {
+		state = rb_entry(node, struct extent_state, rb_node);
+		if (found && state->start != cur_start) {
+			goto out;
+		}
+		if (!(state->state & EXTENT_DELALLOC)) {
+			if (!found)
+				*end = state->end;
+			goto out;
+		}
+		if (!found) {
+			struct extent_state *prev_state;
+			struct rb_node *prev_node = node;
+			while(1) {
+				prev_node = rb_prev(prev_node);
+				if (!prev_node)
+					break;
+				prev_state = rb_entry(prev_node,
+						      struct extent_state,
+						      rb_node);
+				if (!(prev_state->state & EXTENT_DELALLOC))
+					break;
+				state = prev_state;
+				node = prev_node;
+			}
+		}
+		if (state->state & EXTENT_LOCKED) {
+			DEFINE_WAIT(wait);
+			atomic_inc(&state->refs);
+			prepare_to_wait(&state->wq, &wait,
+					TASK_UNINTERRUPTIBLE);
+			write_unlock_irq(&tree->lock);
+			schedule();
+			write_lock_irq(&tree->lock);
+			finish_wait(&state->wq, &wait);
+			free_extent_state(state);
+			goto search_again;
+		}
+		state->state |= EXTENT_LOCKED;
+		if (!found)
+			*start = state->start;
+		found++;
+		*end = state->end;
+		cur_start = state->end + 1;
+		node = rb_next(node);
+		if (!node)
+			break;
+		total_bytes += state->end - state->start + 1;
+		if (total_bytes >= max_bytes)
+			break;
+	}
+out:
+	write_unlock_irq(&tree->lock);
+	return found;
+}
+
+u64 count_range_bits(struct extent_io_tree *tree,
+		     u64 *start, u64 search_end, u64 max_bytes,
+		     unsigned long bits)
+{
+	struct rb_node *node;
+	struct extent_state *state;
+	u64 cur_start = *start;
+	u64 total_bytes = 0;
+	int found = 0;
+
+	if (search_end <= cur_start) {
+		printk("search_end %Lu start %Lu\n", search_end, cur_start);
+		WARN_ON(1);
+		return 0;
+	}
+
+	write_lock_irq(&tree->lock);
+	if (cur_start == 0 && bits == EXTENT_DIRTY) {
+		total_bytes = tree->dirty_bytes;
+		goto out;
+	}
+	/*
+	 * this search will find all the extents that end after
+	 * our range starts.
+	 */
+	node = tree_search(&tree->state, cur_start);
+	if (!node || IS_ERR(node)) {
+		goto out;
+	}
+
+	while(1) {
+		state = rb_entry(node, struct extent_state, rb_node);
+		if (state->start > search_end)
+			break;
+		if (state->end >= cur_start && (state->state & bits)) {
+			total_bytes += min(search_end, state->end) + 1 -
+				       max(cur_start, state->start);
+			if (total_bytes >= max_bytes)
+				break;
+			if (!found) {
+				*start = state->start;
+				found = 1;
+			}
+		}
+		node = rb_next(node);
+		if (!node)
+			break;
+	}
+out:
+	write_unlock_irq(&tree->lock);
+	return total_bytes;
+}
+/*
+ * helper function to lock both pages and extents in the tree.
+ * pages must be locked first.
+ */
+int lock_range(struct extent_io_tree *tree, u64 start, u64 end)
+{
+	unsigned long index = start >> PAGE_CACHE_SHIFT;
+	unsigned long end_index = end >> PAGE_CACHE_SHIFT;
+	struct page *page;
+	int err;
+
+	while (index <= end_index) {
+		page = grab_cache_page(tree->mapping, index);
+		if (!page) {
+			err = -ENOMEM;
+			goto failed;
+		}
+		if (IS_ERR(page)) {
+			err = PTR_ERR(page);
+			goto failed;
+		}
+		index++;
+	}
+	lock_extent(tree, start, end, GFP_NOFS);
+	return 0;
+
+failed:
+	/*
+	 * we failed above in getting the page at 'index', so we undo here
+	 * up to but not including the page at 'index'
+	 */
+	end_index = index;
+	index = start >> PAGE_CACHE_SHIFT;
+	while (index < end_index) {
+		page = find_get_page(tree->mapping, index);
+		unlock_page(page);
+		page_cache_release(page);
+		index++;
+	}
+	return err;
+}
+EXPORT_SYMBOL(lock_range);
+
+/*
+ * helper function to unlock both pages and extents in the tree.
+ */
+int unlock_range(struct extent_io_tree *tree, u64 start, u64 end)
+{
+	unsigned long index = start >> PAGE_CACHE_SHIFT;
+	unsigned long end_index = end >> PAGE_CACHE_SHIFT;
+	struct page *page;
+
+	while (index <= end_index) {
+		page = find_get_page(tree->mapping, index);
+		unlock_page(page);
+		page_cache_release(page);
+		index++;
+	}
+	unlock_extent(tree, start, end, GFP_NOFS);
+	return 0;
+}
+EXPORT_SYMBOL(unlock_range);
+
+int set_state_private(struct extent_io_tree *tree, u64 start, u64 private)
+{
+	struct rb_node *node;
+	struct extent_state *state;
+	int ret = 0;
+
+	write_lock_irq(&tree->lock);
+	/*
+	 * this search will find all the extents that end after
+	 * our range starts.
+	 */
+	node = tree_search(&tree->state, start);
+	if (!node || IS_ERR(node)) {
+		ret = -ENOENT;
+		goto out;
+	}
+	state = rb_entry(node, struct extent_state, rb_node);
+	if (state->start != start) {
+		ret = -ENOENT;
+		goto out;
+	}
+	state->private = private;
+out:
+	write_unlock_irq(&tree->lock);
+	return ret;
+}
+
+int get_state_private(struct extent_io_tree *tree, u64 start, u64 *private)
+{
+	struct rb_node *node;
+	struct extent_state *state;
+	int ret = 0;
+
+	read_lock_irq(&tree->lock);
+	/*
+	 * this search will find all the extents that end after
+	 * our range starts.
+	 */
+	node = tree_search(&tree->state, start);
+	if (!node || IS_ERR(node)) {
+		ret = -ENOENT;
+		goto out;
+	}
+	state = rb_entry(node, struct extent_state, rb_node);
+	if (state->start != start) {
+		ret = -ENOENT;
+		goto out;
+	}
+	*private = state->private;
+out:
+	read_unlock_irq(&tree->lock);
+	return ret;
+}
+
+/*
+ * searches a range in the state tree for a given mask.
+ * If 'filled' == 1, this returns 1 only if ever extent in the tree
+ * has the bits set.  Otherwise, 1 is returned if any bit in the
+ * range is found set.
+ */
+int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
+		   int bits, int filled)
+{
+	struct extent_state *state = NULL;
+	struct rb_node *node;
+	int bitset = 0;
+	unsigned long flags;
+
+	read_lock_irqsave(&tree->lock, flags);
+	node = tree_search(&tree->state, start);
+	while (node && start <= end) {
+		state = rb_entry(node, struct extent_state, rb_node);
+
+		if (filled && state->start > start) {
+			bitset = 0;
+			break;
+		}
+
+		if (state->start > end)
+			break;
+
+		if (state->state & bits) {
+			bitset = 1;
+			if (!filled)
+				break;
+		} else if (filled) {
+			bitset = 0;
+			break;
+		}
+		start = state->end + 1;
+		if (start > end)
+			break;
+		node = rb_next(node);
+		if (!node) {
+			if (filled)
+				bitset = 0;
+			break;
+		}
+	}
+	read_unlock_irqrestore(&tree->lock, flags);
+	return bitset;
+}
+EXPORT_SYMBOL(test_range_bit);
+
+/*
+ * helper function to set a given page up to date if all the
+ * extents in the tree for that page are up to date
+ */
+static int check_page_uptodate(struct extent_io_tree *tree,
+			       struct page *page)
+{
+	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
+	u64 end = start + PAGE_CACHE_SIZE - 1;
+	if (test_range_bit(tree, start, end, EXTENT_UPTODATE, 1))
+		SetPageUptodate(page);
+	return 0;
+}
+
+/*
+ * helper function to unlock a page if all the extents in the tree
+ * for that page are unlocked
+ */
+static int check_page_locked(struct extent_io_tree *tree,
+			     struct page *page)
+{
+	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
+	u64 end = start + PAGE_CACHE_SIZE - 1;
+	if (!test_range_bit(tree, start, end, EXTENT_LOCKED, 0))
+		unlock_page(page);
+	return 0;
+}
+
+/*
+ * helper function to end page writeback if all the extents
+ * in the tree for that page are done with writeback
+ */
+static int check_page_writeback(struct extent_io_tree *tree,
+			     struct page *page)
+{
+	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
+	u64 end = start + PAGE_CACHE_SIZE - 1;
+	if (!test_range_bit(tree, start, end, EXTENT_WRITEBACK, 0))
+		end_page_writeback(page);
+	return 0;
+}
+
+/* lots and lots of room for performance fixes in the end_bio funcs */
+
+/*
+ * after a writepage IO is done, we need to:
+ * clear the uptodate bits on error
+ * clear the writeback bits in the extent tree for this IO
+ * end_page_writeback if the page has no more pending IO
+ *
+ * Scheduling is not allowed, so the extent state tree is expected
+ * to have one and only one object corresponding to this IO.
+ */
+#if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
+static void end_bio_extent_writepage(struct bio *bio, int err)
+#else
+static int end_bio_extent_writepage(struct bio *bio,
+				   unsigned int bytes_done, int err)
+#endif
+{
+	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
+	struct extent_io_tree *tree = bio->bi_private;
+	u64 start;
+	u64 end;
+	int whole_page;
+
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
+	if (bio->bi_size)
+		return 1;
+#endif
+
+	do {
+		struct page *page = bvec->bv_page;
+		start = ((u64)page->index << PAGE_CACHE_SHIFT) +
+			 bvec->bv_offset;
+		end = start + bvec->bv_len - 1;
+
+		if (bvec->bv_offset == 0 && bvec->bv_len == PAGE_CACHE_SIZE)
+			whole_page = 1;
+		else
+			whole_page = 0;
+
+		if (--bvec >= bio->bi_io_vec)
+			prefetchw(&bvec->bv_page->flags);
+
+		if (!uptodate) {
+			clear_extent_uptodate(tree, start, end, GFP_ATOMIC);
+			ClearPageUptodate(page);
+			SetPageError(page);
+		}
+		clear_extent_writeback(tree, start, end, GFP_ATOMIC);
+
+		if (whole_page)
+			end_page_writeback(page);
+		else
+			check_page_writeback(tree, page);
+		if (tree->ops && tree->ops->writepage_end_io_hook)
+			tree->ops->writepage_end_io_hook(page, start, end);
+	} while (bvec >= bio->bi_io_vec);
+
+	bio_put(bio);
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
+	return 0;
+#endif
+}
+
+/*
+ * after a readpage IO is done, we need to:
+ * clear the uptodate bits on error
+ * set the uptodate bits if things worked
+ * set the page up to date if all extents in the tree are uptodate
+ * clear the lock bit in the extent tree
+ * unlock the page if there are no other extents locked for it
+ *
+ * Scheduling is not allowed, so the extent state tree is expected
+ * to have one and only one object corresponding to this IO.
+ */
+#if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
+static void end_bio_extent_readpage(struct bio *bio, int err)
+#else
+static int end_bio_extent_readpage(struct bio *bio,
+				   unsigned int bytes_done, int err)
+#endif
+{
+	int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
+	struct extent_io_tree *tree = bio->bi_private;
+	u64 start;
+	u64 end;
+	int whole_page;
+	int ret;
+
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
+	if (bio->bi_size)
+		return 1;
+#endif
+
+	do {
+		struct page *page = bvec->bv_page;
+		start = ((u64)page->index << PAGE_CACHE_SHIFT) +
+			bvec->bv_offset;
+		end = start + bvec->bv_len - 1;
+
+		if (bvec->bv_offset == 0 && bvec->bv_len == PAGE_CACHE_SIZE)
+			whole_page = 1;
+		else
+			whole_page = 0;
+
+		if (--bvec >= bio->bi_io_vec)
+			prefetchw(&bvec->bv_page->flags);
+
+		if (uptodate && tree->ops && tree->ops->readpage_end_io_hook) {
+			ret = tree->ops->readpage_end_io_hook(page, start, end);
+			if (ret)
+				uptodate = 0;
+		}
+		if (uptodate) {
+			set_extent_uptodate(tree, start, end, GFP_ATOMIC);
+			if (whole_page)
+				SetPageUptodate(page);
+			else
+				check_page_uptodate(tree, page);
+		} else {
+			ClearPageUptodate(page);
+			SetPageError(page);
+		}
+
+		unlock_extent(tree, start, end, GFP_ATOMIC);
+
+		if (whole_page)
+			unlock_page(page);
+		else
+			check_page_locked(tree, page);
+	} while (bvec >= bio->bi_io_vec);
+
+	bio_put(bio);
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
+	return 0;
+#endif
+}
+
+/*
+ * IO done from prepare_write is pretty simple, we just unlock
+ * the structs in the extent tree when done, and set the uptodate bits
+ * as appropriate.
+ */
+#if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
+static void end_bio_extent_preparewrite(struct bio *bio, int err)
+#else
+static int end_bio_extent_preparewrite(struct bio *bio,
+				       unsigned int bytes_done, int err)
+#endif
+{
+	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
+	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
+	struct extent_io_tree *tree = bio->bi_private;
+	u64 start;
+	u64 end;
+
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
+	if (bio->bi_size)
+		return 1;
+#endif
+
+	do {
+		struct page *page = bvec->bv_page;
+		start = ((u64)page->index << PAGE_CACHE_SHIFT) +
+			bvec->bv_offset;
+		end = start + bvec->bv_len - 1;
+
+		if (--bvec >= bio->bi_io_vec)
+			prefetchw(&bvec->bv_page->flags);
+
+		if (uptodate) {
+			set_extent_uptodate(tree, start, end, GFP_ATOMIC);
+		} else {
+			ClearPageUptodate(page);
+			SetPageError(page);
+		}
+
+		unlock_extent(tree, start, end, GFP_ATOMIC);
+
+	} while (bvec >= bio->bi_io_vec);
+
+	bio_put(bio);
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
+	return 0;
+#endif
+}
+
+static struct bio *
+extent_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
+		 gfp_t gfp_flags)
+{
+	struct bio *bio;
+
+	bio = bio_alloc(gfp_flags, nr_vecs);
+
+	if (bio == NULL && (current->flags & PF_MEMALLOC)) {
+		while (!bio && (nr_vecs /= 2))
+			bio = bio_alloc(gfp_flags, nr_vecs);
+	}
+
+	if (bio) {
+		bio->bi_bdev = bdev;
+		bio->bi_sector = first_sector;
+	}
+	return bio;
+}
+
+static int submit_one_bio(int rw, struct bio *bio)
+{
+	u64 maxsector;
+	int ret = 0;
+
+	bio_get(bio);
+
+        maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
+	if (maxsector < bio->bi_sector) {
+		printk("sector too large max %Lu got %llu\n", maxsector,
+			(unsigned long long)bio->bi_sector);
+		WARN_ON(1);
+	}
+
+	submit_bio(rw, bio);
+	if (bio_flagged(bio, BIO_EOPNOTSUPP))
+		ret = -EOPNOTSUPP;
+	bio_put(bio);
+	return ret;
+}
+
+static int submit_extent_page(int rw, struct extent_io_tree *tree,
+			      struct page *page, sector_t sector,
+			      size_t size, unsigned long offset,
+			      struct block_device *bdev,
+			      struct bio **bio_ret,
+			      unsigned long max_pages,
+			      bio_end_io_t end_io_func)
+{
+	int ret = 0;
+	struct bio *bio;
+	int nr;
+
+	if (bio_ret && *bio_ret) {
+		bio = *bio_ret;
+		if (bio->bi_sector + (bio->bi_size >> 9) != sector ||
+		    bio_add_page(bio, page, size, offset) < size) {
+			ret = submit_one_bio(rw, bio);
+			bio = NULL;
+		} else {
+			return 0;
+		}
+	}
+	nr = min_t(int, max_pages, bio_get_nr_vecs(bdev));
+	bio = extent_bio_alloc(bdev, sector, nr, GFP_NOFS | __GFP_HIGH);
+	if (!bio) {
+		printk("failed to allocate bio nr %d\n", nr);
+	}
+	bio_add_page(bio, page, size, offset);
+	bio->bi_end_io = end_io_func;
+	bio->bi_private = tree;
+	if (bio_ret) {
+		*bio_ret = bio;
+	} else {
+		ret = submit_one_bio(rw, bio);
+	}
+
+	return ret;
+}
+
+void set_page_extent_mapped(struct page *page)
+{
+	if (!PagePrivate(page)) {
+		SetPagePrivate(page);
+		WARN_ON(!page->mapping->a_ops->invalidatepage);
+		set_page_private(page, EXTENT_PAGE_PRIVATE);
+		page_cache_get(page);
+	}
+}
+
+void set_page_extent_head(struct page *page, unsigned long len)
+{
+	set_page_private(page, EXTENT_PAGE_PRIVATE_FIRST_PAGE | len << 2);
+}
+
+/*
+ * basic readpage implementation.  Locked extent state structs are inserted
+ * into the tree that are removed when the IO is done (by the end_io
+ * handlers)
+ */
+static int __extent_read_full_page(struct extent_io_tree *tree,
+				   struct page *page,
+				   get_extent_t *get_extent,
+				   struct bio **bio)
+{
+	struct inode *inode = page->mapping->host;
+	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
+	u64 page_end = start + PAGE_CACHE_SIZE - 1;
+	u64 end;
+	u64 cur = start;
+	u64 extent_offset;
+	u64 last_byte = i_size_read(inode);
+	u64 block_start;
+	u64 cur_end;
+	sector_t sector;
+	struct extent_map *em;
+	struct block_device *bdev;
+	int ret;
+	int nr = 0;
+	size_t page_offset = 0;
+	size_t iosize;
+	size_t blocksize = inode->i_sb->s_blocksize;
+
+	set_page_extent_mapped(page);
+
+	end = page_end;
+	lock_extent(tree, start, end, GFP_NOFS);
+
+	while (cur <= end) {
+		if (cur >= last_byte) {
+			char *userpage;
+			iosize = PAGE_CACHE_SIZE - page_offset;
+			userpage = kmap_atomic(page, KM_USER0);
+			memset(userpage + page_offset, 0, iosize);
+			flush_dcache_page(page);
+			kunmap_atomic(userpage, KM_USER0);
+			set_extent_uptodate(tree, cur, cur + iosize - 1,
+					    GFP_NOFS);
+			unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
+			break;
+		}
+		em = get_extent(inode, page, page_offset, cur,
+				end - cur + 1, 0);
+		if (IS_ERR(em) || !em) {
+			SetPageError(page);
+			unlock_extent(tree, cur, end, GFP_NOFS);
+			break;
+		}
+
+		extent_offset = cur - em->start;
+		BUG_ON(extent_map_end(em) <= cur);
+		BUG_ON(end < cur);
+
+		iosize = min(extent_map_end(em) - cur, end - cur + 1);
+		cur_end = min(extent_map_end(em) - 1, end);
+		iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1);
+		sector = (em->block_start + extent_offset) >> 9;
+		bdev = em->bdev;
+		block_start = em->block_start;
+		free_extent_map(em);
+		em = NULL;
+
+		/* we've found a hole, just zero and go on */
+		if (block_start == EXTENT_MAP_HOLE) {
+			char *userpage;
+			userpage = kmap_atomic(page, KM_USER0);
+			memset(userpage + page_offset, 0, iosize);
+			flush_dcache_page(page);
+			kunmap_atomic(userpage, KM_USER0);
+
+			set_extent_uptodate(tree, cur, cur + iosize - 1,
+					    GFP_NOFS);
+			unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
+			cur = cur + iosize;
+			page_offset += iosize;
+			continue;
+		}
+		/* the get_extent function already copied into the page */
+		if (test_range_bit(tree, cur, cur_end, EXTENT_UPTODATE, 1)) {
+			unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
+			cur = cur + iosize;
+			page_offset += iosize;
+			continue;
+		}
+
+		ret = 0;
+		if (tree->ops && tree->ops->readpage_io_hook) {
+			ret = tree->ops->readpage_io_hook(page, cur,
+							  cur + iosize - 1);
+		}
+		if (!ret) {
+			unsigned long nr = (last_byte >> PAGE_CACHE_SHIFT) + 1;
+			nr -= page->index;
+			ret = submit_extent_page(READ, tree, page,
+					 sector, iosize, page_offset,
+					 bdev, bio, nr,
+					 end_bio_extent_readpage);
+		}
+		if (ret)
+			SetPageError(page);
+		cur = cur + iosize;
+		page_offset += iosize;
+		nr++;
+	}
+	if (!nr) {
+		if (!PageError(page))
+			SetPageUptodate(page);
+		unlock_page(page);
+	}
+	return 0;
+}
+
+int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
+			    get_extent_t *get_extent)
+{
+	struct bio *bio = NULL;
+	int ret;
+
+	ret = __extent_read_full_page(tree, page, get_extent, &bio);
+	if (bio)
+		submit_one_bio(READ, bio);
+	return ret;
+}
+EXPORT_SYMBOL(extent_read_full_page);
+
+/*
+ * the writepage semantics are similar to regular writepage.  extent
+ * records are inserted to lock ranges in the tree, and as dirty areas
+ * are found, they are marked writeback.  Then the lock bits are removed
+ * and the end_io handler clears the writeback ranges
+ */
+static int __extent_writepage(struct page *page, struct writeback_control *wbc,
+			      void *data)
+{
+	struct inode *inode = page->mapping->host;
+	struct extent_page_data *epd = data;
+	struct extent_io_tree *tree = epd->tree;
+	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
+	u64 delalloc_start;
+	u64 page_end = start + PAGE_CACHE_SIZE - 1;
+	u64 end;
+	u64 cur = start;
+	u64 extent_offset;
+	u64 last_byte = i_size_read(inode);
+	u64 block_start;
+	u64 iosize;
+	sector_t sector;
+	struct extent_map *em;
+	struct block_device *bdev;
+	int ret;
+	int nr = 0;
+	size_t page_offset = 0;
+	size_t blocksize;
+	loff_t i_size = i_size_read(inode);
+	unsigned long end_index = i_size >> PAGE_CACHE_SHIFT;
+	u64 nr_delalloc;
+	u64 delalloc_end;
+
+	WARN_ON(!PageLocked(page));
+	if (page->index > end_index) {
+		clear_extent_dirty(tree, start, page_end, GFP_NOFS);
+		unlock_page(page);
+		return 0;
+	}
+
+	if (page->index == end_index) {
+		char *userpage;
+
+		size_t offset = i_size & (PAGE_CACHE_SIZE - 1);
+
+		userpage = kmap_atomic(page, KM_USER0);
+		memset(userpage + offset, 0, PAGE_CACHE_SIZE - offset);
+		flush_dcache_page(page);
+		kunmap_atomic(userpage, KM_USER0);
+	}
+
+	set_page_extent_mapped(page);
+
+	delalloc_start = start;
+	delalloc_end = 0;
+	while(delalloc_end < page_end) {
+		nr_delalloc = find_lock_delalloc_range(tree, &delalloc_start,
+						       &delalloc_end,
+						       128 * 1024 * 1024);
+		if (nr_delalloc == 0) {
+			delalloc_start = delalloc_end + 1;
+			continue;
+		}
+		tree->ops->fill_delalloc(inode, delalloc_start,
+					 delalloc_end);
+		clear_extent_bit(tree, delalloc_start,
+				 delalloc_end,
+				 EXTENT_LOCKED | EXTENT_DELALLOC,
+				 1, 0, GFP_NOFS);
+		delalloc_start = delalloc_end + 1;
+	}
+	lock_extent(tree, start, page_end, GFP_NOFS);
+
+	end = page_end;
+	if (test_range_bit(tree, start, page_end, EXTENT_DELALLOC, 0)) {
+		printk("found delalloc bits after lock_extent\n");
+	}
+
+	if (last_byte <= start) {
+		clear_extent_dirty(tree, start, page_end, GFP_NOFS);
+		goto done;
+	}
+
+	set_extent_uptodate(tree, start, page_end, GFP_NOFS);
+	blocksize = inode->i_sb->s_blocksize;
+
+	while (cur <= end) {
+		if (cur >= last_byte) {
+			clear_extent_dirty(tree, cur, page_end, GFP_NOFS);
+			break;
+		}
+		em = epd->get_extent(inode, page, page_offset, cur,
+				     end - cur + 1, 1);
+		if (IS_ERR(em) || !em) {
+			SetPageError(page);
+			break;
+		}
+
+		extent_offset = cur - em->start;
+		BUG_ON(extent_map_end(em) <= cur);
+		BUG_ON(end < cur);
+		iosize = min(extent_map_end(em) - cur, end - cur + 1);
+		iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1);
+		sector = (em->block_start + extent_offset) >> 9;
+		bdev = em->bdev;
+		block_start = em->block_start;
+		free_extent_map(em);
+		em = NULL;
+
+		if (block_start == EXTENT_MAP_HOLE ||
+		    block_start == EXTENT_MAP_INLINE) {
+			clear_extent_dirty(tree, cur,
+					   cur + iosize - 1, GFP_NOFS);
+			cur = cur + iosize;
+			page_offset += iosize;
+			continue;
+		}
+
+		/* leave this out until we have a page_mkwrite call */
+		if (0 && !test_range_bit(tree, cur, cur + iosize - 1,
+				   EXTENT_DIRTY, 0)) {
+			cur = cur + iosize;
+			page_offset += iosize;
+			continue;
+		}
+		clear_extent_dirty(tree, cur, cur + iosize - 1, GFP_NOFS);
+		if (tree->ops && tree->ops->writepage_io_hook) {
+			ret = tree->ops->writepage_io_hook(page, cur,
+						cur + iosize - 1);
+		} else {
+			ret = 0;
+		}
+		if (ret)
+			SetPageError(page);
+		else {
+			unsigned long max_nr = end_index + 1;
+			set_range_writeback(tree, cur, cur + iosize - 1);
+			if (!PageWriteback(page)) {
+				printk("warning page %lu not writeback, "
+				       "cur %llu end %llu\n", page->index,
+				       (unsigned long long)cur,
+				       (unsigned long long)end);
+			}
+
+			ret = submit_extent_page(WRITE, tree, page, sector,
+						 iosize, page_offset, bdev,
+						 &epd->bio, max_nr,
+						 end_bio_extent_writepage);
+			if (ret)
+				SetPageError(page);
+		}
+		cur = cur + iosize;
+		page_offset += iosize;
+		nr++;
+	}
+done:
+	if (nr == 0) {
+		/* make sure the mapping tag for page dirty gets cleared */
+		set_page_writeback(page);
+		end_page_writeback(page);
+	}
+	unlock_extent(tree, start, page_end, GFP_NOFS);
+	unlock_page(page);
+	return 0;
+}
+
+#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
+
+/* Taken directly from 2.6.23 for 2.6.18 back port */
+typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
+                                void *data);
+
+/**
+ * write_cache_pages - walk the list of dirty pages of the given address space
+ * and write all of them.
+ * @mapping: address space structure to write
+ * @wbc: subtract the number of written pages from *@wbc->nr_to_write
+ * @writepage: function called for each page
+ * @data: data passed to writepage function
+ *
+ * If a page is already under I/O, write_cache_pages() skips it, even
+ * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
+ * but it is INCORRECT for data-integrity system calls such as fsync().  fsync()
+ * and msync() need to guarantee that all the data which was dirty at the time
+ * the call was made get new I/O started against them.  If wbc->sync_mode is
+ * WB_SYNC_ALL then we were called for data integrity and we must wait for
+ * existing IO to complete.
+ */
+static int write_cache_pages(struct address_space *mapping,
+		      struct writeback_control *wbc, writepage_t writepage,
+		      void *data)
+{
+	struct backing_dev_info *bdi = mapping->backing_dev_info;
+	int ret = 0;
+	int done = 0;
+	struct pagevec pvec;
+	int nr_pages;
+	pgoff_t index;
+	pgoff_t end;		/* Inclusive */
+	int scanned = 0;
+	int range_whole = 0;
+
+	if (wbc->nonblocking && bdi_write_congested(bdi)) {
+		wbc->encountered_congestion = 1;
+		return 0;
+	}
+
+	pagevec_init(&pvec, 0);
+	if (wbc->range_cyclic) {
+		index = mapping->writeback_index; /* Start from prev offset */
+		end = -1;
+	} else {
+		index = wbc->range_start >> PAGE_CACHE_SHIFT;
+		end = wbc->range_end >> PAGE_CACHE_SHIFT;
+		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
+			range_whole = 1;
+		scanned = 1;
+	}
+retry:
+	while (!done && (index <= end) &&
+	       (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
+					      PAGECACHE_TAG_DIRTY,
+					      min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
+		unsigned i;
+
+		scanned = 1;
+		for (i = 0; i < nr_pages; i++) {
+			struct page *page = pvec.pages[i];
+
+			/*
+			 * At this point we hold neither mapping->tree_lock nor
+			 * lock on the page itself: the page may be truncated or
+			 * invalidated (changing page->mapping to NULL), or even
+			 * swizzled back from swapper_space to tmpfs file
+			 * mapping
+			 */
+			lock_page(page);
+
+			if (unlikely(page->mapping != mapping)) {
+				unlock_page(page);
+				continue;
+			}
+
+			if (!wbc->range_cyclic && page->index > end) {
+				done = 1;
+				unlock_page(page);
+				continue;
+			}
+
+			if (wbc->sync_mode != WB_SYNC_NONE)
+				wait_on_page_writeback(page);
+
+			if (PageWriteback(page) ||
+			    !clear_page_dirty_for_io(page)) {
+				unlock_page(page);
+				continue;
+			}
+
+			ret = (*writepage)(page, wbc, data);
+
+			if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
+				unlock_page(page);
+				ret = 0;
+			}
+			if (ret || (--(wbc->nr_to_write) <= 0))
+				done = 1;
+			if (wbc->nonblocking && bdi_write_congested(bdi)) {
+				wbc->encountered_congestion = 1;
+				done = 1;
+			}
+		}
+		pagevec_release(&pvec);
+		cond_resched();
+	}
+	if (!scanned && !done) {
+		/*
+		 * We hit the last page and there is more work to be done: wrap
+		 * back to the start of the file
+		 */
+		scanned = 1;
+		index = 0;
+		goto retry;
+	}
+	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
+		mapping->writeback_index = index;
+	return ret;
+}
+#endif
+
+int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
+			  get_extent_t *get_extent,
+			  struct writeback_control *wbc)
+{
+	int ret;
+	struct address_space *mapping = page->mapping;
+	struct extent_page_data epd = {
+		.bio = NULL,
+		.tree = tree,
+		.get_extent = get_extent,
+	};
+	struct writeback_control wbc_writepages = {
+		.bdi		= wbc->bdi,
+		.sync_mode	= WB_SYNC_NONE,
+		.older_than_this = NULL,
+		.nr_to_write	= 64,
+		.range_start	= page_offset(page) + PAGE_CACHE_SIZE,
+		.range_end	= (loff_t)-1,
+	};
+
+
+	ret = __extent_writepage(page, wbc, &epd);
+
+	write_cache_pages(mapping, &wbc_writepages, __extent_writepage, &epd);
+	if (epd.bio) {
+		submit_one_bio(WRITE, epd.bio);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(extent_write_full_page);
+
+
+int extent_writepages(struct extent_io_tree *tree,
+		      struct address_space *mapping,
+		      get_extent_t *get_extent,
+		      struct writeback_control *wbc)
+{
+	int ret = 0;
+	struct extent_page_data epd = {
+		.bio = NULL,
+		.tree = tree,
+		.get_extent = get_extent,
+	};
+
+	ret = write_cache_pages(mapping, wbc, __extent_writepage, &epd);
+	if (epd.bio) {
+		submit_one_bio(WRITE, epd.bio);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(extent_writepages);
+
+int extent_readpages(struct extent_io_tree *tree,
+		     struct address_space *mapping,
+		     struct list_head *pages, unsigned nr_pages,
+		     get_extent_t get_extent)
+{
+	struct bio *bio = NULL;
+	unsigned page_idx;
+	struct pagevec pvec;
+
+	pagevec_init(&pvec, 0);
+	for (page_idx = 0; page_idx < nr_pages; page_idx++) {
+		struct page *page = list_entry(pages->prev, struct page, lru);
+
+		prefetchw(&page->flags);
+		list_del(&page->lru);
+		/*
+		 * what we want to do here is call add_to_page_cache_lru,
+		 * but that isn't exported, so we reproduce it here
+		 */
+		if (!add_to_page_cache(page, mapping,
+					page->index, GFP_KERNEL)) {
+
+			/* open coding of lru_cache_add, also not exported */
+			page_cache_get(page);
+			if (!pagevec_add(&pvec, page))
+				__pagevec_lru_add(&pvec);
+			__extent_read_full_page(tree, page, get_extent, &bio);
+		}
+		page_cache_release(page);
+	}
+	if (pagevec_count(&pvec))
+		__pagevec_lru_add(&pvec);
+	BUG_ON(!list_empty(pages));
+	if (bio)
+		submit_one_bio(READ, bio);
+	return 0;
+}
+EXPORT_SYMBOL(extent_readpages);
+
+/*
+ * basic invalidatepage code, this waits on any locked or writeback
+ * ranges corresponding to the page, and then deletes any extent state
+ * records from the tree
+ */
+int extent_invalidatepage(struct extent_io_tree *tree,
+			  struct page *page, unsigned long offset)
+{
+	u64 start = ((u64)page->index << PAGE_CACHE_SHIFT);
+	u64 end = start + PAGE_CACHE_SIZE - 1;
+	size_t blocksize = page->mapping->host->i_sb->s_blocksize;
+
+	start += (offset + blocksize -1) & ~(blocksize - 1);
+	if (start > end)
+		return 0;
+
+	lock_extent(tree, start, end, GFP_NOFS);
+	wait_on_extent_writeback(tree, start, end);
+	clear_extent_bit(tree, start, end,
+			 EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC,
+			 1, 1, GFP_NOFS);
+	return 0;
+}
+EXPORT_SYMBOL(extent_invalidatepage);
+
+/*
+ * simple commit_write call, set_range_dirty is used to mark both
+ * the pages and the extent records as dirty
+ */
+int extent_commit_write(struct extent_io_tree *tree,
+			struct inode *inode, struct page *page,
+			unsigned from, unsigned to)
+{
+	loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
+
+	set_page_extent_mapped(page);
+	set_page_dirty(page);
+
+	if (pos > inode->i_size) {
+		i_size_write(inode, pos);
+		mark_inode_dirty(inode);
+	}
+	return 0;
+}
+EXPORT_SYMBOL(extent_commit_write);
+
+int extent_prepare_write(struct extent_io_tree *tree,
+			 struct inode *inode, struct page *page,
+			 unsigned from, unsigned to, get_extent_t *get_extent)
+{
+	u64 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
+	u64 page_end = page_start + PAGE_CACHE_SIZE - 1;
+	u64 block_start;
+	u64 orig_block_start;
+	u64 block_end;
+	u64 cur_end;
+	struct extent_map *em;
+	unsigned blocksize = 1 << inode->i_blkbits;
+	size_t page_offset = 0;
+	size_t block_off_start;
+	size_t block_off_end;
+	int err = 0;
+	int iocount = 0;
+	int ret = 0;
+	int isnew;
+
+	set_page_extent_mapped(page);
+
+	block_start = (page_start + from) & ~((u64)blocksize - 1);
+	block_end = (page_start + to - 1) | (blocksize - 1);
+	orig_block_start = block_start;
+
+	lock_extent(tree, page_start, page_end, GFP_NOFS);
+	while(block_start <= block_end) {
+		em = get_extent(inode, page, page_offset, block_start,
+				block_end - block_start + 1, 1);
+		if (IS_ERR(em) || !em) {
+			goto err;
+		}
+		cur_end = min(block_end, extent_map_end(em) - 1);
+		block_off_start = block_start & (PAGE_CACHE_SIZE - 1);
+		block_off_end = block_off_start + blocksize;
+		isnew = clear_extent_new(tree, block_start, cur_end, GFP_NOFS);
+
+		if (!PageUptodate(page) && isnew &&
+		    (block_off_end > to || block_off_start < from)) {
+			void *kaddr;
+
+			kaddr = kmap_atomic(page, KM_USER0);
+			if (block_off_end > to)
+				memset(kaddr + to, 0, block_off_end - to);
+			if (block_off_start < from)
+				memset(kaddr + block_off_start, 0,
+				       from - block_off_start);
+			flush_dcache_page(page);
+			kunmap_atomic(kaddr, KM_USER0);
+		}
+		if ((em->block_start != EXTENT_MAP_HOLE &&
+		     em->block_start != EXTENT_MAP_INLINE) &&
+		    !isnew && !PageUptodate(page) &&
+		    (block_off_end > to || block_off_start < from) &&
+		    !test_range_bit(tree, block_start, cur_end,
+				    EXTENT_UPTODATE, 1)) {
+			u64 sector;
+			u64 extent_offset = block_start - em->start;
+			size_t iosize;
+			sector = (em->block_start + extent_offset) >> 9;
+			iosize = (cur_end - block_start + blocksize) &
+				~((u64)blocksize - 1);
+			/*
+			 * we've already got the extent locked, but we
+			 * need to split the state such that our end_bio
+			 * handler can clear the lock.
+			 */
+			set_extent_bit(tree, block_start,
+				       block_start + iosize - 1,
+				       EXTENT_LOCKED, 0, NULL, GFP_NOFS);
+			ret = submit_extent_page(READ, tree, page,
+					 sector, iosize, page_offset, em->bdev,
+					 NULL, 1,
+					 end_bio_extent_preparewrite);
+			iocount++;
+			block_start = block_start + iosize;
+		} else {
+			set_extent_uptodate(tree, block_start, cur_end,
+					    GFP_NOFS);
+			unlock_extent(tree, block_start, cur_end, GFP_NOFS);
+			block_start = cur_end + 1;
+		}
+		page_offset = block_start & (PAGE_CACHE_SIZE - 1);
+		free_extent_map(em);
+	}
+	if (iocount) {
+		wait_extent_bit(tree, orig_block_start,
+				block_end, EXTENT_LOCKED);
+	}
+	check_page_uptodate(tree, page);
+err:
+	/* FIXME, zero out newly allocated blocks on error */
+	return err;
+}
+EXPORT_SYMBOL(extent_prepare_write);
+
+/*
+ * a helper for releasepage.  As long as there are no locked extents
+ * in the range corresponding to the page, both state records and extent
+ * map records are removed
+ */
+int try_release_extent_mapping(struct extent_map_tree *map,
+			       struct extent_io_tree *tree, struct page *page)
+{
+	struct extent_map *em;
+	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
+	u64 end = start + PAGE_CACHE_SIZE - 1;
+	u64 orig_start = start;
+	int ret = 1;
+
+	while (start <= end) {
+		spin_lock(&map->lock);
+		em = lookup_extent_mapping(map, start, end);
+		if (!em || IS_ERR(em)) {
+			spin_unlock(&map->lock);
+			break;
+		}
+		if (!test_range_bit(tree, em->start, extent_map_end(em) - 1,
+				    EXTENT_LOCKED, 0)) {
+			remove_extent_mapping(map, em);
+			/* once for the rb tree */
+			free_extent_map(em);
+		}
+		start = extent_map_end(em);
+		spin_unlock(&map->lock);
+
+		/* once for us */
+		free_extent_map(em);
+	}
+	if (test_range_bit(tree, orig_start, end, EXTENT_LOCKED, 0))
+		ret = 0;
+	else
+		clear_extent_bit(tree, orig_start, end, EXTENT_UPTODATE,
+				 1, 1, GFP_NOFS);
+	return ret;
+}
+EXPORT_SYMBOL(try_release_extent_mapping);
+
+sector_t extent_bmap(struct address_space *mapping, sector_t iblock,
+		get_extent_t *get_extent)
+{
+	struct inode *inode = mapping->host;
+	u64 start = iblock << inode->i_blkbits;
+	sector_t sector = 0;
+	struct extent_map *em;
+
+	em = get_extent(inode, NULL, 0, start, (1 << inode->i_blkbits), 0);
+	if (!em || IS_ERR(em))
+		return 0;
+
+	if (em->block_start == EXTENT_MAP_INLINE ||
+	    em->block_start == EXTENT_MAP_HOLE)
+		goto out;
+
+	sector = (em->block_start + start - em->start) >> inode->i_blkbits;
+printk("bmap finds %Lu %Lu block %Lu\n", em->start, em->len, em->block_start);
+out:
+	free_extent_map(em);
+	return sector;
+}
+
+static int add_lru(struct extent_io_tree *tree, struct extent_buffer *eb)
+{
+	if (list_empty(&eb->lru)) {
+		extent_buffer_get(eb);
+		list_add(&eb->lru, &tree->buffer_lru);
+		tree->lru_size++;
+		if (tree->lru_size >= BUFFER_LRU_MAX) {
+			struct extent_buffer *rm;
+			rm = list_entry(tree->buffer_lru.prev,
+					struct extent_buffer, lru);
+			tree->lru_size--;
+			list_del_init(&rm->lru);
+			free_extent_buffer(rm);
+		}
+	} else
+		list_move(&eb->lru, &tree->buffer_lru);
+	return 0;
+}
+static struct extent_buffer *find_lru(struct extent_io_tree *tree,
+				      u64 start, unsigned long len)
+{
+	struct list_head *lru = &tree->buffer_lru;
+	struct list_head *cur = lru->next;
+	struct extent_buffer *eb;
+
+	if (list_empty(lru))
+		return NULL;
+
+	do {
+		eb = list_entry(cur, struct extent_buffer, lru);
+		if (eb->start == start && eb->len == len) {
+			extent_buffer_get(eb);
+			return eb;
+		}
+		cur = cur->next;
+	} while (cur != lru);
+	return NULL;
+}
+
+static inline unsigned long num_extent_pages(u64 start, u64 len)
+{
+	return ((start + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -
+		(start >> PAGE_CACHE_SHIFT);
+}
+
+static inline struct page *extent_buffer_page(struct extent_buffer *eb,
+					      unsigned long i)
+{
+	struct page *p;
+	struct address_space *mapping;
+
+	if (i == 0)
+		return eb->first_page;
+	i += eb->start >> PAGE_CACHE_SHIFT;
+	mapping = eb->first_page->mapping;
+	read_lock_irq(&mapping->tree_lock);
+	p = radix_tree_lookup(&mapping->page_tree, i);
+	read_unlock_irq(&mapping->tree_lock);
+	return p;
+}
+
+static struct extent_buffer *__alloc_extent_buffer(struct extent_io_tree *tree,
+						   u64 start,
+						   unsigned long len,
+						   gfp_t mask)
+{
+	struct extent_buffer *eb = NULL;
+
+	spin_lock(&tree->lru_lock);
+	eb = find_lru(tree, start, len);
+	spin_unlock(&tree->lru_lock);
+	if (eb) {
+		return eb;
+	}
+
+	eb = kmem_cache_zalloc(extent_buffer_cache, mask);
+	INIT_LIST_HEAD(&eb->lru);
+	eb->start = start;
+	eb->len = len;
+	atomic_set(&eb->refs, 1);
+
+	return eb;
+}
+
+static void __free_extent_buffer(struct extent_buffer *eb)
+{
+	kmem_cache_free(extent_buffer_cache, eb);
+}
+
+struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
+					  u64 start, unsigned long len,
+					  struct page *page0,
+					  gfp_t mask)
+{
+	unsigned long num_pages = num_extent_pages(start, len);
+	unsigned long i;
+	unsigned long index = start >> PAGE_CACHE_SHIFT;
+	struct extent_buffer *eb;
+	struct page *p;
+	struct address_space *mapping = tree->mapping;
+	int uptodate = 1;
+
+	eb = __alloc_extent_buffer(tree, start, len, mask);
+	if (!eb || IS_ERR(eb))
+		return NULL;
+
+	if (eb->flags & EXTENT_BUFFER_FILLED)
+		goto lru_add;
+
+	if (page0) {
+		eb->first_page = page0;
+		i = 1;
+		index++;
+		page_cache_get(page0);
+		mark_page_accessed(page0);
+		set_page_extent_mapped(page0);
+		WARN_ON(!PageUptodate(page0));
+		set_page_extent_head(page0, len);
+	} else {
+		i = 0;
+	}
+	for (; i < num_pages; i++, index++) {
+		p = find_or_create_page(mapping, index, mask | __GFP_HIGHMEM);
+		if (!p) {
+			WARN_ON(1);
+			goto fail;
+		}
+		set_page_extent_mapped(p);
+		mark_page_accessed(p);
+		if (i == 0) {
+			eb->first_page = p;
+			set_page_extent_head(p, len);
+		} else {
+			set_page_private(p, EXTENT_PAGE_PRIVATE);
+		}
+		if (!PageUptodate(p))
+			uptodate = 0;
+		unlock_page(p);
+	}
+	if (uptodate)
+		eb->flags |= EXTENT_UPTODATE;
+	eb->flags |= EXTENT_BUFFER_FILLED;
+
+lru_add:
+	spin_lock(&tree->lru_lock);
+	add_lru(tree, eb);
+	spin_unlock(&tree->lru_lock);
+	return eb;
+
+fail:
+	spin_lock(&tree->lru_lock);
+	list_del_init(&eb->lru);
+	spin_unlock(&tree->lru_lock);
+	if (!atomic_dec_and_test(&eb->refs))
+		return NULL;
+	for (index = 1; index < i; index++) {
+		page_cache_release(extent_buffer_page(eb, index));
+	}
+	if (i > 0)
+		page_cache_release(extent_buffer_page(eb, 0));
+	__free_extent_buffer(eb);
+	return NULL;
+}
+EXPORT_SYMBOL(alloc_extent_buffer);
+
+struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
+					 u64 start, unsigned long len,
+					  gfp_t mask)
+{
+	unsigned long num_pages = num_extent_pages(start, len);
+	unsigned long i;
+	unsigned long index = start >> PAGE_CACHE_SHIFT;
+	struct extent_buffer *eb;
+	struct page *p;
+	struct address_space *mapping = tree->mapping;
+	int uptodate = 1;
+
+	eb = __alloc_extent_buffer(tree, start, len, mask);
+	if (!eb || IS_ERR(eb))
+		return NULL;
+
+	if (eb->flags & EXTENT_BUFFER_FILLED)
+		goto lru_add;
+
+	for (i = 0; i < num_pages; i++, index++) {
+		p = find_lock_page(mapping, index);
+		if (!p) {
+			goto fail;
+		}
+		set_page_extent_mapped(p);
+		mark_page_accessed(p);
+
+		if (i == 0) {
+			eb->first_page = p;
+			set_page_extent_head(p, len);
+		} else {
+			set_page_private(p, EXTENT_PAGE_PRIVATE);
+		}
+
+		if (!PageUptodate(p))
+			uptodate = 0;
+		unlock_page(p);
+	}
+	if (uptodate)
+		eb->flags |= EXTENT_UPTODATE;
+	eb->flags |= EXTENT_BUFFER_FILLED;
+
+lru_add:
+	spin_lock(&tree->lru_lock);
+	add_lru(tree, eb);
+	spin_unlock(&tree->lru_lock);
+	return eb;
+fail:
+	spin_lock(&tree->lru_lock);
+	list_del_init(&eb->lru);
+	spin_unlock(&tree->lru_lock);
+	if (!atomic_dec_and_test(&eb->refs))
+		return NULL;
+	for (index = 1; index < i; index++) {
+		page_cache_release(extent_buffer_page(eb, index));
+	}
+	if (i > 0)
+		page_cache_release(extent_buffer_page(eb, 0));
+	__free_extent_buffer(eb);
+	return NULL;
+}
+EXPORT_SYMBOL(find_extent_buffer);
+
+void free_extent_buffer(struct extent_buffer *eb)
+{
+	unsigned long i;
+	unsigned long num_pages;
+
+	if (!eb)
+		return;
+
+	if (!atomic_dec_and_test(&eb->refs))
+		return;
+
+	WARN_ON(!list_empty(&eb->lru));
+	num_pages = num_extent_pages(eb->start, eb->len);
+
+	for (i = 1; i < num_pages; i++) {
+		page_cache_release(extent_buffer_page(eb, i));
+	}
+	page_cache_release(extent_buffer_page(eb, 0));
+	__free_extent_buffer(eb);
+}
+EXPORT_SYMBOL(free_extent_buffer);
+
+int clear_extent_buffer_dirty(struct extent_io_tree *tree,
+			      struct extent_buffer *eb)
+{
+	int set;
+	unsigned long i;
+	unsigned long num_pages;
+	struct page *page;
+
+	u64 start = eb->start;
+	u64 end = start + eb->len - 1;
+
+	set = clear_extent_dirty(tree, start, end, GFP_NOFS);
+	num_pages = num_extent_pages(eb->start, eb->len);
+
+	for (i = 0; i < num_pages; i++) {
+		page = extent_buffer_page(eb, i);
+		lock_page(page);
+		if (i == 0)
+			set_page_extent_head(page, eb->len);
+		else
+			set_page_private(page, EXTENT_PAGE_PRIVATE);
+
+		/*
+		 * if we're on the last page or the first page and the
+		 * block isn't aligned on a page boundary, do extra checks
+		 * to make sure we don't clean page that is partially dirty
+		 */
+		if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) ||
+		    ((i == num_pages - 1) &&
+		     ((eb->start + eb->len) & (PAGE_CACHE_SIZE - 1)))) {
+			start = (u64)page->index << PAGE_CACHE_SHIFT;
+			end  = start + PAGE_CACHE_SIZE - 1;
+			if (test_range_bit(tree, start, end,
+					   EXTENT_DIRTY, 0)) {
+				unlock_page(page);
+				continue;
+			}
+		}
+		clear_page_dirty_for_io(page);
+		write_lock_irq(&page->mapping->tree_lock);
+		if (!PageDirty(page)) {
+			radix_tree_tag_clear(&page->mapping->page_tree,
+						page_index(page),
+						PAGECACHE_TAG_DIRTY);
+		}
+		write_unlock_irq(&page->mapping->tree_lock);
+		unlock_page(page);
+	}
+	return 0;
+}
+EXPORT_SYMBOL(clear_extent_buffer_dirty);
+
+int wait_on_extent_buffer_writeback(struct extent_io_tree *tree,
+				    struct extent_buffer *eb)
+{
+	return wait_on_extent_writeback(tree, eb->start,
+					eb->start + eb->len - 1);
+}
+EXPORT_SYMBOL(wait_on_extent_buffer_writeback);
+
+int set_extent_buffer_dirty(struct extent_io_tree *tree,
+			     struct extent_buffer *eb)
+{
+	unsigned long i;
+	unsigned long num_pages;
+
+	num_pages = num_extent_pages(eb->start, eb->len);
+	for (i = 0; i < num_pages; i++) {
+		struct page *page = extent_buffer_page(eb, i);
+		/* writepage may need to do something special for the
+		 * first page, we have to make sure page->private is
+		 * properly set.  releasepage may drop page->private
+		 * on us if the page isn't already dirty.
+		 */
+		if (i == 0) {
+			lock_page(page);
+			set_page_extent_head(page, eb->len);
+		} else if (PagePrivate(page) &&
+			   page->private != EXTENT_PAGE_PRIVATE) {
+			lock_page(page);
+			set_page_extent_mapped(page);
+			unlock_page(page);
+		}
+		__set_page_dirty_nobuffers(extent_buffer_page(eb, i));
+		if (i == 0)
+			unlock_page(page);
+	}
+	return set_extent_dirty(tree, eb->start,
+				eb->start + eb->len - 1, GFP_NOFS);
+}
+EXPORT_SYMBOL(set_extent_buffer_dirty);
+
+int set_extent_buffer_uptodate(struct extent_io_tree *tree,
+				struct extent_buffer *eb)
+{
+	unsigned long i;
+	struct page *page;
+	unsigned long num_pages;
+
+	num_pages = num_extent_pages(eb->start, eb->len);
+
+	set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
+			    GFP_NOFS);
+	for (i = 0; i < num_pages; i++) {
+		page = extent_buffer_page(eb, i);
+		if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) ||
+		    ((i == num_pages - 1) &&
+		     ((eb->start + eb->len) & (PAGE_CACHE_SIZE - 1)))) {
+			check_page_uptodate(tree, page);
+			continue;
+		}
+		SetPageUptodate(page);
+	}
+	return 0;
+}
+EXPORT_SYMBOL(set_extent_buffer_uptodate);
+
+int extent_buffer_uptodate(struct extent_io_tree *tree,
+			     struct extent_buffer *eb)
+{
+	if (eb->flags & EXTENT_UPTODATE)
+		return 1;
+	return test_range_bit(tree, eb->start, eb->start + eb->len - 1,
+			   EXTENT_UPTODATE, 1);
+}
+EXPORT_SYMBOL(extent_buffer_uptodate);
+
+int read_extent_buffer_pages(struct extent_io_tree *tree,
+			     struct extent_buffer *eb,
+			     u64 start,
+			     int wait)
+{
+	unsigned long i;
+	unsigned long start_i;
+	struct page *page;
+	int err;
+	int ret = 0;
+	unsigned long num_pages;
+
+	if (eb->flags & EXTENT_UPTODATE)
+		return 0;
+
+	if (0 && test_range_bit(tree, eb->start, eb->start + eb->len - 1,
+			   EXTENT_UPTODATE, 1)) {
+		return 0;
+	}
+
+	if (start) {
+		WARN_ON(start < eb->start);
+		start_i = (start >> PAGE_CACHE_SHIFT) -
+			(eb->start >> PAGE_CACHE_SHIFT);
+	} else {
+		start_i = 0;
+	}
+
+	num_pages = num_extent_pages(eb->start, eb->len);
+	for (i = start_i; i < num_pages; i++) {
+		page = extent_buffer_page(eb, i);
+		if (PageUptodate(page)) {
+			continue;
+		}
+		if (!wait) {
+			if (TestSetPageLocked(page)) {
+				continue;
+			}
+		} else {
+			lock_page(page);
+		}
+		if (!PageUptodate(page)) {
+			err = page->mapping->a_ops->readpage(NULL, page);
+			if (err) {
+				ret = err;
+			}
+		} else {
+			unlock_page(page);
+		}
+	}
+
+	if (ret || !wait) {
+		return ret;
+	}
+
+	for (i = start_i; i < num_pages; i++) {
+		page = extent_buffer_page(eb, i);
+		wait_on_page_locked(page);
+		if (!PageUptodate(page)) {
+			ret = -EIO;
+		}
+	}
+	if (!ret)
+		eb->flags |= EXTENT_UPTODATE;
+	return ret;
+}
+EXPORT_SYMBOL(read_extent_buffer_pages);
+
+void read_extent_buffer(struct extent_buffer *eb, void *dstv,
+			unsigned long start,
+			unsigned long len)
+{
+	size_t cur;
+	size_t offset;
+	struct page *page;
+	char *kaddr;
+	char *dst = (char *)dstv;
+	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
+	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
+	unsigned long num_pages = num_extent_pages(eb->start, eb->len);
+
+	WARN_ON(start > eb->len);
+	WARN_ON(start + len > eb->start + eb->len);
+
+	offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
+
+	while(len > 0) {
+		page = extent_buffer_page(eb, i);
+		if (!PageUptodate(page)) {
+			printk("page %lu not up to date i %lu, total %lu, len %lu\n", page->index, i, num_pages, eb->len);
+			WARN_ON(1);
+		}
+		WARN_ON(!PageUptodate(page));
+
+		cur = min(len, (PAGE_CACHE_SIZE - offset));
+		kaddr = kmap_atomic(page, KM_USER1);
+		memcpy(dst, kaddr + offset, cur);
+		kunmap_atomic(kaddr, KM_USER1);
+
+		dst += cur;
+		len -= cur;
+		offset = 0;
+		i++;
+	}
+}
+EXPORT_SYMBOL(read_extent_buffer);
+
+int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
+			       unsigned long min_len, char **token, char **map,
+			       unsigned long *map_start,
+			       unsigned long *map_len, int km)
+{
+	size_t offset = start & (PAGE_CACHE_SIZE - 1);
+	char *kaddr;
+	struct page *p;
+	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
+	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
+	unsigned long end_i = (start_offset + start + min_len - 1) >>
+		PAGE_CACHE_SHIFT;
+
+	if (i != end_i)
+		return -EINVAL;
+
+	if (i == 0) {
+		offset = start_offset;
+		*map_start = 0;
+	} else {
+		offset = 0;
+		*map_start = ((u64)i << PAGE_CACHE_SHIFT) - start_offset;
+	}
+	if (start + min_len > eb->len) {
+printk("bad mapping eb start %Lu len %lu, wanted %lu %lu\n", eb->start, eb->len, start, min_len);
+		WARN_ON(1);
+	}
+
+	p = extent_buffer_page(eb, i);
+	WARN_ON(!PageUptodate(p));
+	kaddr = kmap_atomic(p, km);
+	*token = kaddr;
+	*map = kaddr + offset;
+	*map_len = PAGE_CACHE_SIZE - offset;
+	return 0;
+}
+EXPORT_SYMBOL(map_private_extent_buffer);
+
+int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
+		      unsigned long min_len,
+		      char **token, char **map,
+		      unsigned long *map_start,
+		      unsigned long *map_len, int km)
+{
+	int err;
+	int save = 0;
+	if (eb->map_token) {
+		unmap_extent_buffer(eb, eb->map_token, km);
+		eb->map_token = NULL;
+		save = 1;
+	}
+	err = map_private_extent_buffer(eb, start, min_len, token, map,
+				       map_start, map_len, km);
+	if (!err && save) {
+		eb->map_token = *token;
+		eb->kaddr = *map;
+		eb->map_start = *map_start;
+		eb->map_len = *map_len;
+	}
+	return err;
+}
+EXPORT_SYMBOL(map_extent_buffer);
+
+void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km)
+{
+	kunmap_atomic(token, km);
+}
+EXPORT_SYMBOL(unmap_extent_buffer);
+
+int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
+			  unsigned long start,
+			  unsigned long len)
+{
+	size_t cur;
+	size_t offset;
+	struct page *page;
+	char *kaddr;
+	char *ptr = (char *)ptrv;
+	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
+	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
+	int ret = 0;
+
+	WARN_ON(start > eb->len);
+	WARN_ON(start + len > eb->start + eb->len);
+
+	offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
+
+	while(len > 0) {
+		page = extent_buffer_page(eb, i);
+		WARN_ON(!PageUptodate(page));
+
+		cur = min(len, (PAGE_CACHE_SIZE - offset));
+
+		kaddr = kmap_atomic(page, KM_USER0);
+		ret = memcmp(ptr, kaddr + offset, cur);
+		kunmap_atomic(kaddr, KM_USER0);
+		if (ret)
+			break;
+
+		ptr += cur;
+		len -= cur;
+		offset = 0;
+		i++;
+	}
+	return ret;
+}
+EXPORT_SYMBOL(memcmp_extent_buffer);
+
+void write_extent_buffer(struct extent_buffer *eb, const void *srcv,
+			 unsigned long start, unsigned long len)
+{
+	size_t cur;
+	size_t offset;
+	struct page *page;
+	char *kaddr;
+	char *src = (char *)srcv;
+	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
+	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
+
+	WARN_ON(start > eb->len);
+	WARN_ON(start + len > eb->start + eb->len);
+
+	offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
+
+	while(len > 0) {
+		page = extent_buffer_page(eb, i);
+		WARN_ON(!PageUptodate(page));
+
+		cur = min(len, PAGE_CACHE_SIZE - offset);
+		kaddr = kmap_atomic(page, KM_USER1);
+		memcpy(kaddr + offset, src, cur);
+		kunmap_atomic(kaddr, KM_USER1);
+
+		src += cur;
+		len -= cur;
+		offset = 0;
+		i++;
+	}
+}
+EXPORT_SYMBOL(write_extent_buffer);
+
+void memset_extent_buffer(struct extent_buffer *eb, char c,
+			  unsigned long start, unsigned long len)
+{
+	size_t cur;
+	size_t offset;
+	struct page *page;
+	char *kaddr;
+	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
+	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
+
+	WARN_ON(start > eb->len);
+	WARN_ON(start + len > eb->start + eb->len);
+
+	offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
+
+	while(len > 0) {
+		page = extent_buffer_page(eb, i);
+		WARN_ON(!PageUptodate(page));
+
+		cur = min(len, PAGE_CACHE_SIZE - offset);
+		kaddr = kmap_atomic(page, KM_USER0);
+		memset(kaddr + offset, c, cur);
+		kunmap_atomic(kaddr, KM_USER0);
+
+		len -= cur;
+		offset = 0;
+		i++;
+	}
+}
+EXPORT_SYMBOL(memset_extent_buffer);
+
+void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
+			unsigned long dst_offset, unsigned long src_offset,
+			unsigned long len)
+{
+	u64 dst_len = dst->len;
+	size_t cur;
+	size_t offset;
+	struct page *page;
+	char *kaddr;
+	size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
+	unsigned long i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
+
+	WARN_ON(src->len != dst_len);
+
+	offset = (start_offset + dst_offset) &
+		((unsigned long)PAGE_CACHE_SIZE - 1);
+
+	while(len > 0) {
+		page = extent_buffer_page(dst, i);
+		WARN_ON(!PageUptodate(page));
+
+		cur = min(len, (unsigned long)(PAGE_CACHE_SIZE - offset));
+
+		kaddr = kmap_atomic(page, KM_USER0);
+		read_extent_buffer(src, kaddr + offset, src_offset, cur);
+		kunmap_atomic(kaddr, KM_USER0);
+
+		src_offset += cur;
+		len -= cur;
+		offset = 0;
+		i++;
+	}
+}
+EXPORT_SYMBOL(copy_extent_buffer);
+
+static void move_pages(struct page *dst_page, struct page *src_page,
+		       unsigned long dst_off, unsigned long src_off,
+		       unsigned long len)
+{
+	char *dst_kaddr = kmap_atomic(dst_page, KM_USER0);
+	if (dst_page == src_page) {
+		memmove(dst_kaddr + dst_off, dst_kaddr + src_off, len);
+	} else {
+		char *src_kaddr = kmap_atomic(src_page, KM_USER1);
+		char *p = dst_kaddr + dst_off + len;
+		char *s = src_kaddr + src_off + len;
+
+		while (len--)
+			*--p = *--s;
+
+		kunmap_atomic(src_kaddr, KM_USER1);
+	}
+	kunmap_atomic(dst_kaddr, KM_USER0);
+}
+
+static void copy_pages(struct page *dst_page, struct page *src_page,
+		       unsigned long dst_off, unsigned long src_off,
+		       unsigned long len)
+{
+	char *dst_kaddr = kmap_atomic(dst_page, KM_USER0);
+	char *src_kaddr;
+
+	if (dst_page != src_page)
+		src_kaddr = kmap_atomic(src_page, KM_USER1);
+	else
+		src_kaddr = dst_kaddr;
+
+	memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len);
+	kunmap_atomic(dst_kaddr, KM_USER0);
+	if (dst_page != src_page)
+		kunmap_atomic(src_kaddr, KM_USER1);
+}
+
+void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
+			   unsigned long src_offset, unsigned long len)
+{
+	size_t cur;
+	size_t dst_off_in_page;
+	size_t src_off_in_page;
+	size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
+	unsigned long dst_i;
+	unsigned long src_i;
+
+	if (src_offset + len > dst->len) {
+		printk("memmove bogus src_offset %lu move len %lu len %lu\n",
+		       src_offset, len, dst->len);
+		BUG_ON(1);
+	}
+	if (dst_offset + len > dst->len) {
+		printk("memmove bogus dst_offset %lu move len %lu len %lu\n",
+		       dst_offset, len, dst->len);
+		BUG_ON(1);
+	}
+
+	while(len > 0) {
+		dst_off_in_page = (start_offset + dst_offset) &
+			((unsigned long)PAGE_CACHE_SIZE - 1);
+		src_off_in_page = (start_offset + src_offset) &
+			((unsigned long)PAGE_CACHE_SIZE - 1);
+
+		dst_i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
+		src_i = (start_offset + src_offset) >> PAGE_CACHE_SHIFT;
+
+		cur = min(len, (unsigned long)(PAGE_CACHE_SIZE -
+					       src_off_in_page));
+		cur = min_t(unsigned long, cur,
+			(unsigned long)(PAGE_CACHE_SIZE - dst_off_in_page));
+
+		copy_pages(extent_buffer_page(dst, dst_i),
+			   extent_buffer_page(dst, src_i),
+			   dst_off_in_page, src_off_in_page, cur);
+
+		src_offset += cur;
+		dst_offset += cur;
+		len -= cur;
+	}
+}
+EXPORT_SYMBOL(memcpy_extent_buffer);
+
+void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
+			   unsigned long src_offset, unsigned long len)
+{
+	size_t cur;
+	size_t dst_off_in_page;
+	size_t src_off_in_page;
+	unsigned long dst_end = dst_offset + len - 1;
+	unsigned long src_end = src_offset + len - 1;
+	size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
+	unsigned long dst_i;
+	unsigned long src_i;
+
+	if (src_offset + len > dst->len) {
+		printk("memmove bogus src_offset %lu move len %lu len %lu\n",
+		       src_offset, len, dst->len);
+		BUG_ON(1);
+	}
+	if (dst_offset + len > dst->len) {
+		printk("memmove bogus dst_offset %lu move len %lu len %lu\n",
+		       dst_offset, len, dst->len);
+		BUG_ON(1);
+	}
+	if (dst_offset < src_offset) {
+		memcpy_extent_buffer(dst, dst_offset, src_offset, len);
+		return;
+	}
+	while(len > 0) {
+		dst_i = (start_offset + dst_end) >> PAGE_CACHE_SHIFT;
+		src_i = (start_offset + src_end) >> PAGE_CACHE_SHIFT;
+
+		dst_off_in_page = (start_offset + dst_end) &
+			((unsigned long)PAGE_CACHE_SIZE - 1);
+		src_off_in_page = (start_offset + src_end) &
+			((unsigned long)PAGE_CACHE_SIZE - 1);
+
+		cur = min_t(unsigned long, len, src_off_in_page + 1);
+		cur = min(cur, dst_off_in_page + 1);
+		move_pages(extent_buffer_page(dst, dst_i),
+			   extent_buffer_page(dst, src_i),
+			   dst_off_in_page - cur + 1,
+			   src_off_in_page - cur + 1, cur);
+
+		dst_end -= cur;
+		src_end -= cur;
+		len -= cur;
+	}
+}
+EXPORT_SYMBOL(memmove_extent_buffer);
diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
new file mode 100644
index 0000000..06be1fe8
--- /dev/null
+++ b/fs/btrfs/extent_io.h
@@ -0,0 +1,193 @@
+#ifndef __EXTENTIO__
+#define __EXTENTIO__
+
+#include <linux/rbtree.h>
+
+/* bits for the extent state */
+#define EXTENT_DIRTY 1
+#define EXTENT_WRITEBACK (1 << 1)
+#define EXTENT_UPTODATE (1 << 2)
+#define EXTENT_LOCKED (1 << 3)
+#define EXTENT_NEW (1 << 4)
+#define EXTENT_DELALLOC (1 << 5)
+#define EXTENT_DEFRAG (1 << 6)
+#define EXTENT_DEFRAG_DONE (1 << 7)
+#define EXTENT_BUFFER_FILLED (1 << 8)
+#define EXTENT_CSUM (1 << 9)
+#define EXTENT_IOBITS (EXTENT_LOCKED | EXTENT_WRITEBACK)
+
+/*
+ * page->private values.  Every page that is controlled by the extent
+ * map has page->private set to one.
+ */
+#define EXTENT_PAGE_PRIVATE 1
+#define EXTENT_PAGE_PRIVATE_FIRST_PAGE 3
+
+struct extent_io_ops {
+	int (*fill_delalloc)(struct inode *inode, u64 start, u64 end);
+	int (*writepage_io_hook)(struct page *page, u64 start, u64 end);
+	int (*readpage_io_hook)(struct page *page, u64 start, u64 end);
+	int (*readpage_end_io_hook)(struct page *page, u64 start, u64 end);
+	void (*writepage_end_io_hook)(struct page *page, u64 start, u64 end);
+};
+
+struct extent_io_tree {
+	struct rb_root state;
+	struct address_space *mapping;
+	u64 dirty_bytes;
+	rwlock_t lock;
+	struct extent_io_ops *ops;
+	spinlock_t lru_lock;
+	struct list_head buffer_lru;
+	int lru_size;
+};
+
+struct extent_state {
+	u64 start;
+	u64 end; /* inclusive */
+	int in_tree;
+	struct rb_node rb_node;
+	wait_queue_head_t wq;
+	atomic_t refs;
+	unsigned long state;
+
+	/* for use by the FS */
+	u64 private;
+
+	struct list_head list;
+};
+
+struct extent_buffer {
+	u64 start;
+	unsigned long len;
+	char *map_token;
+	char *kaddr;
+	unsigned long map_start;
+	unsigned long map_len;
+	struct page *first_page;
+	struct list_head lru;
+	atomic_t refs;
+	int flags;
+};
+
+struct extent_map_tree;
+
+typedef struct extent_map *(get_extent_t)(struct inode *inode,
+					  struct page *page,
+					  size_t page_offset,
+					  u64 start, u64 len,
+					  int create);
+
+void extent_io_tree_init(struct extent_io_tree *tree,
+			  struct address_space *mapping, gfp_t mask);
+void extent_io_tree_empty_lru(struct extent_io_tree *tree);
+int try_release_extent_mapping(struct extent_map_tree *map,
+			       struct extent_io_tree *tree, struct page *page);
+int lock_extent(struct extent_io_tree *tree, u64 start, u64 end, gfp_t mask);
+int unlock_extent(struct extent_io_tree *tree, u64 start, u64 end, gfp_t mask);
+int extent_read_full_page(struct extent_io_tree *tree, struct page *page,
+			  get_extent_t *get_extent);
+int __init extent_io_init(void);
+void extent_io_exit(void);
+
+u64 count_range_bits(struct extent_io_tree *tree,
+		     u64 *start, u64 search_end,
+		     u64 max_bytes, unsigned long bits);
+
+int test_range_bit(struct extent_io_tree *tree, u64 start, u64 end,
+		   int bits, int filled);
+int clear_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
+		      int bits, gfp_t mask);
+int set_extent_bits(struct extent_io_tree *tree, u64 start, u64 end,
+		    int bits, gfp_t mask);
+int set_extent_uptodate(struct extent_io_tree *tree, u64 start, u64 end,
+			gfp_t mask);
+int set_extent_new(struct extent_io_tree *tree, u64 start, u64 end,
+		   gfp_t mask);
+int set_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
+		     gfp_t mask);
+int clear_extent_dirty(struct extent_io_tree *tree, u64 start, u64 end,
+		       gfp_t mask);
+int set_extent_delalloc(struct extent_io_tree *tree, u64 start, u64 end,
+		     gfp_t mask);
+int find_first_extent_bit(struct extent_io_tree *tree, u64 start,
+			  u64 *start_ret, u64 *end_ret, int bits);
+int extent_invalidatepage(struct extent_io_tree *tree,
+			  struct page *page, unsigned long offset);
+int extent_write_full_page(struct extent_io_tree *tree, struct page *page,
+			  get_extent_t *get_extent,
+			  struct writeback_control *wbc);
+int extent_writepages(struct extent_io_tree *tree,
+		      struct address_space *mapping,
+		      get_extent_t *get_extent,
+		      struct writeback_control *wbc);
+int extent_readpages(struct extent_io_tree *tree,
+		     struct address_space *mapping,
+		     struct list_head *pages, unsigned nr_pages,
+		     get_extent_t get_extent);
+int extent_prepare_write(struct extent_io_tree *tree,
+			 struct inode *inode, struct page *page,
+			 unsigned from, unsigned to, get_extent_t *get_extent);
+int extent_commit_write(struct extent_io_tree *tree,
+			struct inode *inode, struct page *page,
+			unsigned from, unsigned to);
+sector_t extent_bmap(struct address_space *mapping, sector_t iblock,
+		get_extent_t *get_extent);
+int set_range_dirty(struct extent_io_tree *tree, u64 start, u64 end);
+int set_state_private(struct extent_io_tree *tree, u64 start, u64 private);
+int get_state_private(struct extent_io_tree *tree, u64 start, u64 *private);
+void set_page_extent_mapped(struct page *page);
+
+struct extent_buffer *alloc_extent_buffer(struct extent_io_tree *tree,
+					  u64 start, unsigned long len,
+					  struct page *page0,
+					  gfp_t mask);
+struct extent_buffer *find_extent_buffer(struct extent_io_tree *tree,
+					 u64 start, unsigned long len,
+					  gfp_t mask);
+void free_extent_buffer(struct extent_buffer *eb);
+int read_extent_buffer_pages(struct extent_io_tree *tree,
+			     struct extent_buffer *eb, u64 start, int wait);
+
+static inline void extent_buffer_get(struct extent_buffer *eb)
+{
+	atomic_inc(&eb->refs);
+}
+
+int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
+			  unsigned long start,
+			  unsigned long len);
+void read_extent_buffer(struct extent_buffer *eb, void *dst,
+			unsigned long start,
+			unsigned long len);
+void write_extent_buffer(struct extent_buffer *eb, const void *src,
+			 unsigned long start, unsigned long len);
+void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
+			unsigned long dst_offset, unsigned long src_offset,
+			unsigned long len);
+void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
+			   unsigned long src_offset, unsigned long len);
+void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
+			   unsigned long src_offset, unsigned long len);
+void memset_extent_buffer(struct extent_buffer *eb, char c,
+			  unsigned long start, unsigned long len);
+int wait_on_extent_buffer_writeback(struct extent_io_tree *tree,
+				    struct extent_buffer *eb);
+int clear_extent_buffer_dirty(struct extent_io_tree *tree,
+			      struct extent_buffer *eb);
+int set_extent_buffer_dirty(struct extent_io_tree *tree,
+			     struct extent_buffer *eb);
+int set_extent_buffer_uptodate(struct extent_io_tree *tree,
+			       struct extent_buffer *eb);
+int extent_buffer_uptodate(struct extent_io_tree *tree,
+			   struct extent_buffer *eb);
+int map_extent_buffer(struct extent_buffer *eb, unsigned long offset,
+		      unsigned long min_len, char **token, char **map,
+		      unsigned long *map_start,
+		      unsigned long *map_len, int km);
+int map_private_extent_buffer(struct extent_buffer *eb, unsigned long offset,
+		      unsigned long min_len, char **token, char **map,
+		      unsigned long *map_start,
+		      unsigned long *map_len, int km);
+void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km);
+#endif
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 010a287..268ad8f 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -1,17 +1,10 @@
-#include <linux/bitops.h>
-#include <linux/slab.h>
-#include <linux/bio.h>
-#include <linux/mm.h>
+#include <linux/err.h>
 #include <linux/gfp.h>
-#include <linux/pagemap.h>
-#include <linux/page-flags.h>
+#include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/spinlock.h>
-#include <linux/blkdev.h>
-#include <linux/swap.h>
 #include <linux/version.h>
-#include <linux/writeback.h>
-#include <linux/pagevec.h>
+#include <linux/hardirq.h>
 #include "extent_map.h"
 
 /* temporary define until extent_map moves out of btrfs */
@@ -21,27 +14,6 @@ struct kmem_cache *btrfs_cache_create(const char *name, size_t size,
 						    unsigned long));
 
 static struct kmem_cache *extent_map_cache;
-static struct kmem_cache *extent_state_cache;
-static struct kmem_cache *extent_buffer_cache;
-
-static LIST_HEAD(buffers);
-static LIST_HEAD(states);
-
-static spinlock_t state_lock = SPIN_LOCK_UNLOCKED;
-#define BUFFER_LRU_MAX 64
-
-struct tree_entry {
-	u64 start;
-	u64 end;
-	int in_tree;
-	struct rb_node rb_node;
-};
-
-struct extent_page_data {
-	struct bio *bio;
-	struct extent_map_tree *tree;
-	get_extent_t *get_extent;
-};
 
 int __init extent_map_init(void)
 {
@@ -50,72 +22,23 @@ int __init extent_map_init(void)
 					    NULL);
 	if (!extent_map_cache)
 		return -ENOMEM;
-	extent_state_cache = btrfs_cache_create("extent_state",
-					    sizeof(struct extent_state), 0,
-					    NULL);
-	if (!extent_state_cache)
-		goto free_map_cache;
-	extent_buffer_cache = btrfs_cache_create("extent_buffers",
-					    sizeof(struct extent_buffer), 0,
-					    NULL);
-	if (!extent_buffer_cache)
-		goto free_state_cache;
 	return 0;
-
-free_state_cache:
-	kmem_cache_destroy(extent_state_cache);
-free_map_cache:
-	kmem_cache_destroy(extent_map_cache);
-	return -ENOMEM;
 }
 
 void extent_map_exit(void)
 {
-	struct extent_state *state;
-
-	while (!list_empty(&states)) {
-		state = list_entry(states.next, struct extent_state, list);
-		printk("state leak: start %Lu end %Lu state %lu in tree %d refs %d\n", state->start, state->end, state->state, state->in_tree, atomic_read(&state->refs));
-		list_del(&state->list);
-		kmem_cache_free(extent_state_cache, state);
-
-	}
-
 	if (extent_map_cache)
 		kmem_cache_destroy(extent_map_cache);
-	if (extent_state_cache)
-		kmem_cache_destroy(extent_state_cache);
-	if (extent_buffer_cache)
-		kmem_cache_destroy(extent_buffer_cache);
 }
 
-void extent_map_tree_init(struct extent_map_tree *tree,
-			  struct address_space *mapping, gfp_t mask)
+void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask)
 {
 	tree->map.rb_node = NULL;
-	tree->state.rb_node = NULL;
-	tree->ops = NULL;
-	tree->dirty_bytes = 0;
-	rwlock_init(&tree->lock);
-	spin_lock_init(&tree->lru_lock);
-	tree->mapping = mapping;
-	INIT_LIST_HEAD(&tree->buffer_lru);
-	tree->lru_size = 0;
+	tree->last = NULL;
+	spin_lock_init(&tree->lock);
 }
 EXPORT_SYMBOL(extent_map_tree_init);
 
-void extent_map_tree_empty_lru(struct extent_map_tree *tree)
-{
-	struct extent_buffer *eb;
-	while(!list_empty(&tree->buffer_lru)) {
-		eb = list_entry(tree->buffer_lru.next, struct extent_buffer,
-				lru);
-		list_del_init(&eb->lru);
-		free_extent_buffer(eb);
-	}
-}
-EXPORT_SYMBOL(extent_map_tree_empty_lru);
-
 struct extent_map *alloc_extent_map(gfp_t mask)
 {
 	struct extent_map *em;
@@ -123,6 +46,7 @@ struct extent_map *alloc_extent_map(gfp_t mask)
 	if (!em || IS_ERR(em))
 		return em;
 	em->in_tree = 0;
+	em->flags = 0;
 	atomic_set(&em->refs, 1);
 	return em;
 }
@@ -132,6 +56,7 @@ void free_extent_map(struct extent_map *em)
 {
 	if (!em)
 		return;
+	WARN_ON(atomic_read(&em->refs) == 0);
 	if (atomic_dec_and_test(&em->refs)) {
 		WARN_ON(em->in_tree);
 		kmem_cache_free(extent_map_cache, em);
@@ -139,64 +64,28 @@ void free_extent_map(struct extent_map *em)
 }
 EXPORT_SYMBOL(free_extent_map);
 
-
-struct extent_state *alloc_extent_state(gfp_t mask)
-{
-	struct extent_state *state;
-	unsigned long flags;
-
-	state = kmem_cache_alloc(extent_state_cache, mask);
-	if (!state || IS_ERR(state))
-		return state;
-	state->state = 0;
-	state->in_tree = 0;
-	state->private = 0;
-
-	spin_lock_irqsave(&state_lock, flags);
-	list_add(&state->list, &states);
-	spin_unlock_irqrestore(&state_lock, flags);
-
-	atomic_set(&state->refs, 1);
-	init_waitqueue_head(&state->wq);
-	return state;
-}
-EXPORT_SYMBOL(alloc_extent_state);
-
-void free_extent_state(struct extent_state *state)
-{
-	unsigned long flags;
-	if (!state)
-		return;
-	if (atomic_dec_and_test(&state->refs)) {
-		WARN_ON(state->in_tree);
-		spin_lock_irqsave(&state_lock, flags);
-		list_del(&state->list);
-		spin_unlock_irqrestore(&state_lock, flags);
-		kmem_cache_free(extent_state_cache, state);
-	}
-}
-EXPORT_SYMBOL(free_extent_state);
-
 static struct rb_node *tree_insert(struct rb_root *root, u64 offset,
 				   struct rb_node *node)
 {
 	struct rb_node ** p = &root->rb_node;
 	struct rb_node * parent = NULL;
-	struct tree_entry *entry;
+	struct extent_map *entry;
 
 	while(*p) {
 		parent = *p;
-		entry = rb_entry(parent, struct tree_entry, rb_node);
+		entry = rb_entry(parent, struct extent_map, rb_node);
+
+		WARN_ON(!entry->in_tree);
 
 		if (offset < entry->start)
 			p = &(*p)->rb_left;
-		else if (offset > entry->end)
+		else if (offset >= extent_map_end(entry))
 			p = &(*p)->rb_right;
 		else
 			return parent;
 	}
 
-	entry = rb_entry(node, struct tree_entry, rb_node);
+	entry = rb_entry(node, struct extent_map, rb_node);
 	entry->in_tree = 1;
 	rb_link_node(node, parent, p);
 	rb_insert_color(node, root);
@@ -210,17 +99,19 @@ static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
 	struct rb_node * n = root->rb_node;
 	struct rb_node *prev = NULL;
 	struct rb_node *orig_prev = NULL;
-	struct tree_entry *entry;
-	struct tree_entry *prev_entry = NULL;
+	struct extent_map *entry;
+	struct extent_map *prev_entry = NULL;
 
 	while(n) {
-		entry = rb_entry(n, struct tree_entry, rb_node);
+		entry = rb_entry(n, struct extent_map, rb_node);
 		prev = n;
 		prev_entry = entry;
 
+		WARN_ON(!entry->in_tree);
+
 		if (offset < entry->start)
 			n = n->rb_left;
-		else if (offset > entry->end)
+		else if (offset >= extent_map_end(entry))
 			n = n->rb_right;
 		else
 			return n;
@@ -228,19 +119,19 @@ static struct rb_node *__tree_search(struct rb_root *root, u64 offset,
 
 	if (prev_ret) {
 		orig_prev = prev;
-		while(prev && offset > prev_entry->end) {
+		while(prev && offset >= extent_map_end(prev_entry)) {
 			prev = rb_next(prev);
-			prev_entry = rb_entry(prev, struct tree_entry, rb_node);
+			prev_entry = rb_entry(prev, struct extent_map, rb_node);
 		}
 		*prev_ret = prev;
 		prev = orig_prev;
 	}
 
 	if (next_ret) {
-		prev_entry = rb_entry(prev, struct tree_entry, rb_node);
+		prev_entry = rb_entry(prev, struct extent_map, rb_node);
 		while(prev && offset < prev_entry->start) {
 			prev = rb_prev(prev);
-			prev_entry = rb_entry(prev, struct tree_entry, rb_node);
+			prev_entry = rb_entry(prev, struct extent_map, rb_node);
 		}
 		*next_ret = prev;
 	}
@@ -257,22 +148,26 @@ static inline struct rb_node *tree_search(struct rb_root *root, u64 offset)
 	return ret;
 }
 
-static int tree_delete(struct rb_root *root, u64 offset)
+static int mergable_maps(struct extent_map *prev, struct extent_map *next)
 {
-	struct rb_node *node;
-	struct tree_entry *entry;
-
-	node = __tree_search(root, offset, NULL, NULL);
-	if (!node)
-		return -ENOENT;
-	entry = rb_entry(node, struct tree_entry, rb_node);
-	entry->in_tree = 0;
-	rb_erase(node, root);
+	if (extent_map_end(prev) == next->start &&
+	    prev->flags == next->flags &&
+	    prev->bdev == next->bdev &&
+	    ((next->block_start == EXTENT_MAP_HOLE &&
+	      prev->block_start == EXTENT_MAP_HOLE) ||
+	     (next->block_start == EXTENT_MAP_INLINE &&
+	      prev->block_start == EXTENT_MAP_INLINE) ||
+	     (next->block_start == EXTENT_MAP_DELALLOC &&
+	      prev->block_start == EXTENT_MAP_DELALLOC) ||
+	     (next->block_start < EXTENT_MAP_LAST_BYTE - 1 &&
+	      next->block_start == extent_map_block_end(prev)))) {
+		return 1;
+	}
 	return 0;
 }
 
 /*
- * add_extent_mapping tries a simple backward merge with existing
+ * add_extent_mapping tries a simple forward/backward merge with existing
  * mappings.  The extent_map struct passed in will be inserted into
  * the tree directly (no copies made, just a reference taken).
  */
@@ -280,13 +175,12 @@ int add_extent_mapping(struct extent_map_tree *tree,
 		       struct extent_map *em)
 {
 	int ret = 0;
-	struct extent_map *prev = NULL;
+	struct extent_map *merge = NULL;
 	struct rb_node *rb;
 
-	write_lock_irq(&tree->lock);
-	rb = tree_insert(&tree->map, em->end, &em->rb_node);
+	rb = tree_insert(&tree->map, em->start, &em->rb_node);
 	if (rb) {
-		prev = rb_entry(rb, struct extent_map, rb_node);
+		merge = rb_entry(rb, struct extent_map, rb_node);
 		ret = -EEXIST;
 		goto out;
 	}
@@ -294,53 +188,60 @@ int add_extent_mapping(struct extent_map_tree *tree,
 	if (em->start != 0) {
 		rb = rb_prev(&em->rb_node);
 		if (rb)
-			prev = rb_entry(rb, struct extent_map, rb_node);
-		if (prev && prev->end + 1 == em->start &&
-		    ((em->block_start == EXTENT_MAP_HOLE &&
-		      prev->block_start == EXTENT_MAP_HOLE) ||
-		     (em->block_start == EXTENT_MAP_INLINE &&
-		      prev->block_start == EXTENT_MAP_INLINE) ||
-		     (em->block_start == EXTENT_MAP_DELALLOC &&
-		      prev->block_start == EXTENT_MAP_DELALLOC) ||
-		     (em->block_start < EXTENT_MAP_DELALLOC - 1 &&
-		      em->block_start == prev->block_end + 1))) {
-			em->start = prev->start;
-			em->block_start = prev->block_start;
-			rb_erase(&prev->rb_node, &tree->map);
-			prev->in_tree = 0;
-			free_extent_map(prev);
+			merge = rb_entry(rb, struct extent_map, rb_node);
+		if (rb && mergable_maps(merge, em)) {
+			em->start = merge->start;
+			em->len += merge->len;
+			em->block_start = merge->block_start;
+			merge->in_tree = 0;
+			rb_erase(&merge->rb_node, &tree->map);
+			free_extent_map(merge);
 		}
 	 }
+	rb = rb_next(&em->rb_node);
+	if (rb)
+		merge = rb_entry(rb, struct extent_map, rb_node);
+	if (rb && mergable_maps(em, merge)) {
+		em->len += merge->len;
+		rb_erase(&merge->rb_node, &tree->map);
+		merge->in_tree = 0;
+		free_extent_map(merge);
+	}
+	tree->last = em;
 out:
-	write_unlock_irq(&tree->lock);
 	return ret;
 }
 EXPORT_SYMBOL(add_extent_mapping);
 
+static u64 range_end(u64 start, u64 len)
+{
+	if (start + len < start)
+		return (u64)-1;
+	return start + len;
+}
+
 /*
  * lookup_extent_mapping returns the first extent_map struct in the
- * tree that intersects the [start, end] (inclusive) range.  There may
+ * tree that intersects the [start, len] range.  There may
  * be additional objects in the tree that intersect, so check the object
  * returned carefully to make sure you don't need additional lookups.
  */
 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
-					 u64 start, u64 end)
+					 u64 start, u64 len)
 {
 	struct extent_map *em;
 	struct rb_node *rb_node;
-	struct rb_node *prev = NULL;
-	struct rb_node *next = NULL;
+	struct rb_node *prev = NULL; struct rb_node *next = NULL; u64 end = range_end(start, len); em = tree->last; if (em && end > em->start && start < extent_map_end(em)) goto found;
 
-	read_lock_irq(&tree->lock);
 	rb_node = __tree_search(&tree->map, start, &prev, &next);
 	if (!rb_node && prev) {
 		em = rb_entry(prev, struct extent_map, rb_node);
-		if (em->start <= end && em->end >= start)
+		if (end > em->start && start < extent_map_end(em))
 			goto found;
 	}
 	if (!rb_node && next) {
 		em = rb_entry(next, struct extent_map, rb_node);
-		if (em->start <= end && em->end >= start)
+		if (end > em->start && start < extent_map_end(em))
 			goto found;
 	}
 	if (!rb_node) {
@@ -352,14 +253,16 @@ struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
 		goto out;
 	}
 	em = rb_entry(rb_node, struct extent_map, rb_node);
-	if (em->end < start || em->start > end) {
-		em = NULL;
-		goto out;
-	}
+	if (end > em->start && start < extent_map_end(em))
+		goto found;
+
+	em = NULL;
+	goto out;
+
 found:
 	atomic_inc(&em->refs);
+	tree->last = em;
 out:
-	read_unlock_irq(&tree->lock);
 	return em;
 }
 EXPORT_SYMBOL(lookup_extent_mapping);
@@ -370,2866 +273,12 @@ EXPORT_SYMBOL(lookup_extent_mapping);
  */
 int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
 {
-	int ret;
-
-	write_lock_irq(&tree->lock);
-	ret = tree_delete(&tree->map, em->end);
-	write_unlock_irq(&tree->lock);
-	return ret;
-}
-EXPORT_SYMBOL(remove_extent_mapping);
-
-/*
- * utility function to look for merge candidates inside a given range.
- * Any extents with matching state are merged together into a single
- * extent in the tree.  Extents with EXTENT_IO in their state field
- * are not merged because the end_io handlers need to be able to do
- * operations on them without sleeping (or doing allocations/splits).
- *
- * This should be called with the tree lock held.
- */
-static int merge_state(struct extent_map_tree *tree,
-		       struct extent_state *state)
-{
-	struct extent_state *other;
-	struct rb_node *other_node;
-
-	if (state->state & EXTENT_IOBITS)
-		return 0;
-
-	other_node = rb_prev(&state->rb_node);
-	if (other_node) {
-		other = rb_entry(other_node, struct extent_state, rb_node);
-		if (other->end == state->start - 1 &&
-		    other->state == state->state) {
-			state->start = other->start;
-			other->in_tree = 0;
-			rb_erase(&other->rb_node, &tree->state);
-			free_extent_state(other);
-		}
-	}
-	other_node = rb_next(&state->rb_node);
-	if (other_node) {
-		other = rb_entry(other_node, struct extent_state, rb_node);
-		if (other->start == state->end + 1 &&
-		    other->state == state->state) {
-			other->start = state->start;
-			state->in_tree = 0;
-			rb_erase(&state->rb_node, &tree->state);
-			free_extent_state(state);
-		}
-	}
-	return 0;
-}
-
-/*
- * insert an extent_state struct into the tree.  'bits' are set on the
- * struct before it is inserted.
- *
- * This may return -EEXIST if the extent is already there, in which case the
- * state struct is freed.
- *
- * The tree lock is not taken internally.  This is a utility function and
- * probably isn't what you want to call (see set/clear_extent_bit).
- */
-static int insert_state(struct extent_map_tree *tree,
-			struct extent_state *state, u64 start, u64 end,
-			int bits)
-{
-	struct rb_node *node;
-
-	if (end < start) {
-		printk("end < start %Lu %Lu\n", end, start);
-		WARN_ON(1);
-	}
-	if (bits & EXTENT_DIRTY)
-		tree->dirty_bytes += end - start + 1;
-	state->state |= bits;
-	state->start = start;
-	state->end = end;
-	node = tree_insert(&tree->state, end, &state->rb_node);
-	if (node) {
-		struct extent_state *found;
-		found = rb_entry(node, struct extent_state, rb_node);
-		printk("found node %Lu %Lu on insert of %Lu %Lu\n", found->start, found->end, start, end);
-		free_extent_state(state);
-		return -EEXIST;
-	}
-	merge_state(tree, state);
-	return 0;
-}
-
-/*
- * split a given extent state struct in two, inserting the preallocated
- * struct 'prealloc' as the newly created second half.  'split' indicates an
- * offset inside 'orig' where it should be split.
- *
- * Before calling,
- * the tree has 'orig' at [orig->start, orig->end].  After calling, there
- * are two extent state structs in the tree:
- * prealloc: [orig->start, split - 1]
- * orig: [ split, orig->end ]
- *
- * The tree locks are not taken by this function. They need to be held
- * by the caller.
- */
-static int split_state(struct extent_map_tree *tree, struct extent_state *orig,
-		       struct extent_state *prealloc, u64 split)
-{
-	struct rb_node *node;
-	prealloc->start = orig->start;
-	prealloc->end = split - 1;
-	prealloc->state = orig->state;
-	orig->start = split;
-
-	node = tree_insert(&tree->state, prealloc->end, &prealloc->rb_node);
-	if (node) {
-		struct extent_state *found;
-		found = rb_entry(node, struct extent_state, rb_node);
-		printk("found node %Lu %Lu on insert of %Lu %Lu\n", found->start, found->end, prealloc->start, prealloc->end);
-		free_extent_state(prealloc);
-		return -EEXIST;
-	}
-	return 0;
-}
-
-/*
- * utility function to clear some bits in an extent state struct.
- * it will optionally wake up any one waiting on this state (wake == 1), or
- * forcibly remove the state from the tree (delete == 1).
- *
- * If no bits are set on the state struct after clearing things, the
- * struct is freed and removed from the tree
- */
-static int clear_state_bit(struct extent_map_tree *tree,
-			    struct extent_state *state, int bits, int wake,
-			    int delete)
-{
-	int ret = state->state & bits;
-
-	if ((bits & EXTENT_DIRTY) && (state->state & EXTENT_DIRTY)) {
-		u64 range = state->end - state->start + 1;
-		WARN_ON(range > tree->dirty_bytes);
-		tree->dirty_bytes -= range;
-	}
-	state->state &= ~bits;
-	if (wake)
-		wake_up(&state->wq);
-	if (delete || state->state == 0) {
-		if (state->in_tree) {
-			rb_erase(&state->rb_node, &tree->state);
-			state->in_tree = 0;
-			free_extent_state(state);
-		} else {
-			WARN_ON(1);
-		}
-	} else {
-		merge_state(tree, state);
-	}
-	return ret;
-}
-
-/*
- * clear some bits on a range in the tree.  This may require splitting
- * or inserting elements in the tree, so the gfp mask is used to
- * indicate which allocations or sleeping are allowed.
- *
- * pass 'wake' == 1 to kick any sleepers, and 'delete' == 1 to remove
- * the given range from the tree regardless of state (ie for truncate).
- *
- * the range [start, end] is inclusive.
- *
- * This takes the tree lock, and returns < 0 on error, > 0 if any of the
- * bits were already set, or zero if none of the bits were already set.
- */
-int clear_extent_bit(struct extent_map_tree *tree, u64 start, u64 end,
-		     int bits, int wake, int delete, gfp_t mask)
-{
-	struct extent_state *state;
-	struct extent_state *prealloc = NULL;
-	struct rb_node *node;
-	unsigned long flags;
-	int err;
-	int set = 0;
-
-again:
-	if (!prealloc && (mask & __GFP_WAIT)) {
-		prealloc = alloc_extent_state(mask);
-		if (!prealloc)
-			return -ENOMEM;
-	}
-
-	write_lock_irqsave(&tree->lock, flags);
-	/*
-	 * this search will find the extents that end after
-	 * our range starts
-	 */
-	node = tree_search(&tree->state, start);
-	if (!node)
-		goto out;
-	state = rb_entry(node, struct extent_state, rb_node);
-	if (state->start > end)
-		goto out;
-	WARN_ON(state->end < start);
-
-	/*
-	 *     | ---- desired range ---- |
-	 *  | state | or
-	 *  | ------------- state -------------- |
-	 *
-	 * We need to split the extent we found, and may flip
-	 * bits on second half.
-	 *
-	 * If the extent we found extends past our range, we
-	 * just split and search again.  It'll get split again
-	 * the next time though.
-	 *
-	 * If the extent we found is inside our range, we clear
-	 * the desired bit on it.
-	 */
-
-	if (state->start < start) {
-		err = split_state(tree, state, prealloc, start);
-		BUG_ON(err == -EEXIST);
-		prealloc = NULL;
-		if (err)
-			goto out;
-		if (state->end <= end) {
-			start = state->end + 1;
-			set |= clear_state_bit(tree, state, bits,
-					wake, delete);
-		} else {
-			start = state->start;
-		}
-		goto search_again;
-	}
-	/*
-	 * | ---- desired range ---- |
-	 *                        | state |
-	 * We need to split the extent, and clear the bit
-	 * on the first half
-	 */
-	if (state->start <= end && state->end > end) {
-		err = split_state(tree, state, prealloc, end + 1);
-		BUG_ON(err == -EEXIST);
-
-		if (wake)
-			wake_up(&state->wq);
-		set |= clear_state_bit(tree, prealloc, bits,
-				       wake, delete);
-		prealloc = NULL;
-		goto out;
-	}
-
-	start = state->end + 1;
-	set |= clear_state_bit(tree, state, bits, wake, delete);
-	goto search_again;
-
-out:
-	write_unlock_irqrestore(&tree->lock, flags);
-	if (prealloc)
-		free_extent_state(prealloc);
-
-	return set;
-
-search_again:
-	if (start > end)
-		goto out;
-	write_unlock_irqrestore(&tree->lock, flags);
-	if (mask & __GFP_WAIT)
-		cond_resched();
-	goto again;
-}
-EXPORT_SYMBOL(clear_extent_bit);
-
-static int wait_on_state(struct extent_map_tree *tree,
-			 struct extent_state *state)
-{
-	DEFINE_WAIT(wait);
-	prepare_to_wait(&state->wq, &wait, TASK_UNINTERRUPTIBLE);
-	read_unlock_irq(&tree->lock);
-	schedule();
-	read_lock_irq(&tree->lock);
-	finish_wait(&state->wq, &wait);
-	return 0;
-}
-
-/*
- * waits for one or more bits to clear on a range in the state tree.
- * The range [start, end] is inclusive.
- * The tree lock is taken by this function
- */
-int wait_extent_bit(struct extent_map_tree *tree, u64 start, u64 end, int bits)
-{
-	struct extent_state *state;
-	struct rb_node *node;
-
-	read_lock_irq(&tree->lock);
-again:
-	while (1) {
-		/*
-		 * this search will find all the extents that end after
-		 * our range starts
-		 */
-		node = tree_search(&tree->state, start);
-		if (!node)
-			break;
-
-		state = rb_entry(node, struct extent_state, rb_node);
-
-		if (state->start > end)
-			goto out;
-
-		if (state->state & bits) {
-			start = state->start;
-			atomic_inc(&state->refs);
-			wait_on_state(tree, state);
-			free_extent_state(state);
-			goto again;
-		}
-		start = state->end + 1;
-
-		if (start > end)
-			break;
-
-		if (need_resched()) {
-			read_unlock_irq(&tree->lock);
-			cond_resched();
-			read_lock_irq(&tree->lock);
-		}
-	}
-out:
-	read_unlock_irq(&tree->lock);
-	return 0;
-}
-EXPORT_SYMBOL(wait_extent_bit);
-
-static void set_state_bits(struct extent_map_tree *tree,
-			   struct extent_state *state,
-			   int bits)
-{
-	if ((bits & EXTENT_DIRTY) && !(state->state & EXTENT_DIRTY)) {
-		u64 range = state->end - state->start + 1;
-		tree->dirty_bytes += range;
-	}
-	state->state |= bits;
-}
-
-/*
- * set some bits on a range in the tree.  This may require allocations
- * or sleeping, so the gfp mask is used to indicate what is allowed.
- *
- * If 'exclusive' == 1, this will fail with -EEXIST if some part of the
- * range already has the desired bits set.  The start of the existing
- * range is returned in failed_start in this case.
- *
- * [start, end] is inclusive
- * This takes the tree lock.
- */
-int set_extent_bit(struct extent_map_tree *tree, u64 start, u64 end, int bits,
-		   int exclusive, u64 *failed_start, gfp_t mask)
-{
-	struct extent_state *state;
-	struct extent_state *prealloc = NULL;
-	struct rb_node *node;
-	unsigned long flags;
-	int err = 0;
-	int set;
-	u64 last_start;
-	u64 last_end;
-again:
-	if (!prealloc && (mask & __GFP_WAIT)) {
-		prealloc = alloc_extent_state(mask);
-		if (!prealloc)
-			return -ENOMEM;
-	}
-
-	write_lock_irqsave(&tree->lock, flags);
-	/*
-	 * this search will find all the extents that end after
-	 * our range starts.
-	 */
-	node = tree_search(&tree->state, start);
-	if (!node) {
-		err = insert_state(tree, prealloc, start, end, bits);
-		prealloc = NULL;
-		BUG_ON(err == -EEXIST);
-		goto out;
-	}
-
-	state = rb_entry(node, struct extent_state, rb_node);
-	last_start = state->start;
-	last_end = state->end;
-
-	/*
-	 * | ---- desired range ---- |
-	 * | state |
-	 *
-	 * Just lock what we found and keep going
-	 */
-	if (state->start == start && state->end <= end) {
-		set = state->state & bits;
-		if (set && exclusive) {
-			*failed_start = state->start;
-			err = -EEXIST;
-			goto out;
-		}
-		set_state_bits(tree, state, bits);
-		start = state->end + 1;
-		merge_state(tree, state);
-		goto search_again;
-	}
-
-	/*
-	 *     | ---- desired range ---- |
-	 * | state |
-	 *   or
-	 * | ------------- state -------------- |
-	 *
-	 * We need to split the extent we found, and may flip bits on
-	 * second half.
-	 *
-	 * If the extent we found extends past our
-	 * range, we just split and search again.  It'll get split
-	 * again the next time though.
-	 *
-	 * If the extent we found is inside our range, we set the
-	 * desired bit on it.
-	 */
-	if (state->start < start) {
-		set = state->state & bits;
-		if (exclusive && set) {
-			*failed_start = start;
-			err = -EEXIST;
-			goto out;
-		}
-		err = split_state(tree, state, prealloc, start);
-		BUG_ON(err == -EEXIST);
-		prealloc = NULL;
-		if (err)
-			goto out;
-		if (state->end <= end) {
-			set_state_bits(tree, state, bits);
-			start = state->end + 1;
-			merge_state(tree, state);
-		} else {
-			start = state->start;
-		}
-		goto search_again;
-	}
-	/*
-	 * | ---- desired range ---- |
-	 *     | state | or               | state |
-	 *
-	 * There's a hole, we need to insert something in it and
-	 * ignore the extent we found.
-	 */
-	if (state->start > start) {
-		u64 this_end;
-		if (end < last_start)
-			this_end = end;
-		else
-			this_end = last_start -1;
-		err = insert_state(tree, prealloc, start, this_end,
-				   bits);
-		prealloc = NULL;
-		BUG_ON(err == -EEXIST);
-		if (err)
-			goto out;
-		start = this_end + 1;
-		goto search_again;
-	}
-	/*
-	 * | ---- desired range ---- |
-	 *                        | state |
-	 * We need to split the extent, and set the bit
-	 * on the first half
-	 */
-	if (state->start <= end && state->end > end) {
-		set = state->state & bits;
-		if (exclusive && set) {
-			*failed_start = start;
-			err = -EEXIST;
-			goto out;
-		}
-		err = split_state(tree, state, prealloc, end + 1);
-		BUG_ON(err == -EEXIST);
-
-		set_state_bits(tree, prealloc, bits);
-		merge_state(tree, prealloc);
-		prealloc = NULL;
-		goto out;
-	}
-
-	goto search_again;
-
-out:
-	write_unlock_irqrestore(&tree->lock, flags);
-	if (prealloc)
-		free_extent_state(prealloc);
-
-	return err;
-
-search_again:
-	if (start > end)
-		goto out;
-	write_unlock_irqrestore(&tree->lock, flags);
-	if (mask & __GFP_WAIT)
-		cond_resched();
-	goto again;
-}
-EXPORT_SYMBOL(set_extent_bit);
-
-/* wrappers around set/clear extent bit */
-int set_extent_dirty(struct extent_map_tree *tree, u64 start, u64 end,
-		     gfp_t mask)
-{
-	return set_extent_bit(tree, start, end, EXTENT_DIRTY, 0, NULL,
-			      mask);
-}
-EXPORT_SYMBOL(set_extent_dirty);
-
-int set_extent_bits(struct extent_map_tree *tree, u64 start, u64 end,
-		    int bits, gfp_t mask)
-{
-	return set_extent_bit(tree, start, end, bits, 0, NULL,
-			      mask);
-}
-EXPORT_SYMBOL(set_extent_bits);
-
-int clear_extent_bits(struct extent_map_tree *tree, u64 start, u64 end,
-		      int bits, gfp_t mask)
-{
-	return clear_extent_bit(tree, start, end, bits, 0, 0, mask);
-}
-EXPORT_SYMBOL(clear_extent_bits);
-
-int set_extent_delalloc(struct extent_map_tree *tree, u64 start, u64 end,
-		     gfp_t mask)
-{
-	return set_extent_bit(tree, start, end,
-			      EXTENT_DELALLOC | EXTENT_DIRTY, 0, NULL,
-			      mask);
-}
-EXPORT_SYMBOL(set_extent_delalloc);
-
-int clear_extent_dirty(struct extent_map_tree *tree, u64 start, u64 end,
-		       gfp_t mask)
-{
-	return clear_extent_bit(tree, start, end,
-				EXTENT_DIRTY | EXTENT_DELALLOC, 0, 0, mask);
-}
-EXPORT_SYMBOL(clear_extent_dirty);
-
-int set_extent_new(struct extent_map_tree *tree, u64 start, u64 end,
-		     gfp_t mask)
-{
-	return set_extent_bit(tree, start, end, EXTENT_NEW, 0, NULL,
-			      mask);
-}
-EXPORT_SYMBOL(set_extent_new);
-
-int clear_extent_new(struct extent_map_tree *tree, u64 start, u64 end,
-		       gfp_t mask)
-{
-	return clear_extent_bit(tree, start, end, EXTENT_NEW, 0, 0, mask);
-}
-EXPORT_SYMBOL(clear_extent_new);
-
-int set_extent_uptodate(struct extent_map_tree *tree, u64 start, u64 end,
-			gfp_t mask)
-{
-	return set_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, NULL,
-			      mask);
-}
-EXPORT_SYMBOL(set_extent_uptodate);
-
-int clear_extent_uptodate(struct extent_map_tree *tree, u64 start, u64 end,
-			  gfp_t mask)
-{
-	return clear_extent_bit(tree, start, end, EXTENT_UPTODATE, 0, 0, mask);
-}
-EXPORT_SYMBOL(clear_extent_uptodate);
-
-int set_extent_writeback(struct extent_map_tree *tree, u64 start, u64 end,
-			 gfp_t mask)
-{
-	return set_extent_bit(tree, start, end, EXTENT_WRITEBACK,
-			      0, NULL, mask);
-}
-EXPORT_SYMBOL(set_extent_writeback);
-
-int clear_extent_writeback(struct extent_map_tree *tree, u64 start, u64 end,
-			   gfp_t mask)
-{
-	return clear_extent_bit(tree, start, end, EXTENT_WRITEBACK, 1, 0, mask);
-}
-EXPORT_SYMBOL(clear_extent_writeback);
-
-int wait_on_extent_writeback(struct extent_map_tree *tree, u64 start, u64 end)
-{
-	return wait_extent_bit(tree, start, end, EXTENT_WRITEBACK);
-}
-EXPORT_SYMBOL(wait_on_extent_writeback);
-
-/*
- * locks a range in ascending order, waiting for any locked regions
- * it hits on the way.  [start,end] are inclusive, and this will sleep.
- */
-int lock_extent(struct extent_map_tree *tree, u64 start, u64 end, gfp_t mask)
-{
-	int err;
-	u64 failed_start;
-	while (1) {
-		err = set_extent_bit(tree, start, end, EXTENT_LOCKED, 1,
-				     &failed_start, mask);
-		if (err == -EEXIST && (mask & __GFP_WAIT)) {
-			wait_extent_bit(tree, failed_start, end, EXTENT_LOCKED);
-			start = failed_start;
-		} else {
-			break;
-		}
-		WARN_ON(start > end);
-	}
-	return err;
-}
-EXPORT_SYMBOL(lock_extent);
-
-int unlock_extent(struct extent_map_tree *tree, u64 start, u64 end,
-		  gfp_t mask)
-{
-	return clear_extent_bit(tree, start, end, EXTENT_LOCKED, 1, 0, mask);
-}
-EXPORT_SYMBOL(unlock_extent);
-
-/*
- * helper function to set pages and extents in the tree dirty
- */
-int set_range_dirty(struct extent_map_tree *tree, u64 start, u64 end)
-{
-	unsigned long index = start >> PAGE_CACHE_SHIFT;
-	unsigned long end_index = end >> PAGE_CACHE_SHIFT;
-	struct page *page;
-
-	while (index <= end_index) {
-		page = find_get_page(tree->mapping, index);
-		BUG_ON(!page);
-		__set_page_dirty_nobuffers(page);
-		page_cache_release(page);
-		index++;
-	}
-	set_extent_dirty(tree, start, end, GFP_NOFS);
-	return 0;
-}
-EXPORT_SYMBOL(set_range_dirty);
-
-/*
- * helper function to set both pages and extents in the tree writeback
- */
-int set_range_writeback(struct extent_map_tree *tree, u64 start, u64 end)
-{
-	unsigned long index = start >> PAGE_CACHE_SHIFT;
-	unsigned long end_index = end >> PAGE_CACHE_SHIFT;
-	struct page *page;
-
-	while (index <= end_index) {
-		page = find_get_page(tree->mapping, index);
-		BUG_ON(!page);
-		set_page_writeback(page);
-		page_cache_release(page);
-		index++;
-	}
-	set_extent_writeback(tree, start, end, GFP_NOFS);
-	return 0;
-}
-EXPORT_SYMBOL(set_range_writeback);
-
-int find_first_extent_bit(struct extent_map_tree *tree, u64 start,
-			  u64 *start_ret, u64 *end_ret, int bits)
-{
-	struct rb_node *node;
-	struct extent_state *state;
-	int ret = 1;
-
-	read_lock_irq(&tree->lock);
-	/*
-	 * this search will find all the extents that end after
-	 * our range starts.
-	 */
-	node = tree_search(&tree->state, start);
-	if (!node || IS_ERR(node)) {
-		goto out;
-	}
-
-	while(1) {
-		state = rb_entry(node, struct extent_state, rb_node);
-		if (state->end >= start && (state->state & bits)) {
-			*start_ret = state->start;
-			*end_ret = state->end;
-			ret = 0;
-			break;
-		}
-		node = rb_next(node);
-		if (!node)
-			break;
-	}
-out:
-	read_unlock_irq(&tree->lock);
-	return ret;
-}
-EXPORT_SYMBOL(find_first_extent_bit);
-
-u64 find_lock_delalloc_range(struct extent_map_tree *tree,
-			     u64 *start, u64 *end, u64 max_bytes)
-{
-	struct rb_node *node;
-	struct extent_state *state;
-	u64 cur_start = *start;
-	u64 found = 0;
-	u64 total_bytes = 0;
-
-	write_lock_irq(&tree->lock);
-	/*
-	 * this search will find all the extents that end after
-	 * our range starts.
-	 */
-search_again:
-	node = tree_search(&tree->state, cur_start);
-	if (!node || IS_ERR(node)) {
-		*end = (u64)-1;
-		goto out;
-	}
-
-	while(1) {
-		state = rb_entry(node, struct extent_state, rb_node);
-		if (found && state->start != cur_start) {
-			goto out;
-		}
-		if (!(state->state & EXTENT_DELALLOC)) {
-			if (!found)
-				*end = state->end;
-			goto out;
-		}
-		if (!found) {
-			struct extent_state *prev_state;
-			struct rb_node *prev_node = node;
-			while(1) {
-				prev_node = rb_prev(prev_node);
-				if (!prev_node)
-					break;
-				prev_state = rb_entry(prev_node,
-						      struct extent_state,
-						      rb_node);
-				if (!(prev_state->state & EXTENT_DELALLOC))
-					break;
-				state = prev_state;
-				node = prev_node;
-			}
-		}
-		if (state->state & EXTENT_LOCKED) {
-			DEFINE_WAIT(wait);
-			atomic_inc(&state->refs);
-			prepare_to_wait(&state->wq, &wait,
-					TASK_UNINTERRUPTIBLE);
-			write_unlock_irq(&tree->lock);
-			schedule();
-			write_lock_irq(&tree->lock);
-			finish_wait(&state->wq, &wait);
-			free_extent_state(state);
-			goto search_again;
-		}
-		state->state |= EXTENT_LOCKED;
-		if (!found)
-			*start = state->start;
-		found++;
-		*end = state->end;
-		cur_start = state->end + 1;
-		node = rb_next(node);
-		if (!node)
-			break;
-		total_bytes += state->end - state->start + 1;
-		if (total_bytes >= max_bytes)
-			break;
-	}
-out:
-	write_unlock_irq(&tree->lock);
-	return found;
-}
-
-u64 count_range_bits(struct extent_map_tree *tree,
-		     u64 *start, u64 search_end, u64 max_bytes,
-		     unsigned long bits)
-{
-	struct rb_node *node;
-	struct extent_state *state;
-	u64 cur_start = *start;
-	u64 total_bytes = 0;
-	int found = 0;
-
-	if (search_end <= cur_start) {
-		printk("search_end %Lu start %Lu\n", search_end, cur_start);
-		WARN_ON(1);
-		return 0;
-	}
-
-	write_lock_irq(&tree->lock);
-	if (cur_start == 0 && bits == EXTENT_DIRTY) {
-		total_bytes = tree->dirty_bytes;
-		goto out;
-	}
-	/*
-	 * this search will find all the extents that end after
-	 * our range starts.
-	 */
-	node = tree_search(&tree->state, cur_start);
-	if (!node || IS_ERR(node)) {
-		goto out;
-	}
-
-	while(1) {
-		state = rb_entry(node, struct extent_state, rb_node);
-		if (state->start > search_end)
-			break;
-		if (state->end >= cur_start && (state->state & bits)) {
-			total_bytes += min(search_end, state->end) + 1 -
-				       max(cur_start, state->start);
-			if (total_bytes >= max_bytes)
-				break;
-			if (!found) {
-				*start = state->start;
-				found = 1;
-			}
-		}
-		node = rb_next(node);
-		if (!node)
-			break;
-	}
-out:
-	write_unlock_irq(&tree->lock);
-	return total_bytes;
-}
-/*
- * helper function to lock both pages and extents in the tree.
- * pages must be locked first.
- */
-int lock_range(struct extent_map_tree *tree, u64 start, u64 end)
-{
-	unsigned long index = start >> PAGE_CACHE_SHIFT;
-	unsigned long end_index = end >> PAGE_CACHE_SHIFT;
-	struct page *page;
-	int err;
-
-	while (index <= end_index) {
-		page = grab_cache_page(tree->mapping, index);
-		if (!page) {
-			err = -ENOMEM;
-			goto failed;
-		}
-		if (IS_ERR(page)) {
-			err = PTR_ERR(page);
-			goto failed;
-		}
-		index++;
-	}
-	lock_extent(tree, start, end, GFP_NOFS);
-	return 0;
-
-failed:
-	/*
-	 * we failed above in getting the page at 'index', so we undo here
-	 * up to but not including the page at 'index'
-	 */
-	end_index = index;
-	index = start >> PAGE_CACHE_SHIFT;
-	while (index < end_index) {
-		page = find_get_page(tree->mapping, index);
-		unlock_page(page);
-		page_cache_release(page);
-		index++;
-	}
-	return err;
-}
-EXPORT_SYMBOL(lock_range);
-
-/*
- * helper function to unlock both pages and extents in the tree.
- */
-int unlock_range(struct extent_map_tree *tree, u64 start, u64 end)
-{
-	unsigned long index = start >> PAGE_CACHE_SHIFT;
-	unsigned long end_index = end >> PAGE_CACHE_SHIFT;
-	struct page *page;
-
-	while (index <= end_index) {
-		page = find_get_page(tree->mapping, index);
-		unlock_page(page);
-		page_cache_release(page);
-		index++;
-	}
-	unlock_extent(tree, start, end, GFP_NOFS);
-	return 0;
-}
-EXPORT_SYMBOL(unlock_range);
-
-int set_state_private(struct extent_map_tree *tree, u64 start, u64 private)
-{
-	struct rb_node *node;
-	struct extent_state *state;
-	int ret = 0;
-
-	write_lock_irq(&tree->lock);
-	/*
-	 * this search will find all the extents that end after
-	 * our range starts.
-	 */
-	node = tree_search(&tree->state, start);
-	if (!node || IS_ERR(node)) {
-		ret = -ENOENT;
-		goto out;
-	}
-	state = rb_entry(node, struct extent_state, rb_node);
-	if (state->start != start) {
-		ret = -ENOENT;
-		goto out;
-	}
-	state->private = private;
-out:
-	write_unlock_irq(&tree->lock);
-	return ret;
-}
-
-int get_state_private(struct extent_map_tree *tree, u64 start, u64 *private)
-{
-	struct rb_node *node;
-	struct extent_state *state;
-	int ret = 0;
-
-	read_lock_irq(&tree->lock);
-	/*
-	 * this search will find all the extents that end after
-	 * our range starts.
-	 */
-	node = tree_search(&tree->state, start);
-	if (!node || IS_ERR(node)) {
-		ret = -ENOENT;
-		goto out;
-	}
-	state = rb_entry(node, struct extent_state, rb_node);
-	if (state->start != start) {
-		ret = -ENOENT;
-		goto out;
-	}
-	*private = state->private;
-out:
-	read_unlock_irq(&tree->lock);
-	return ret;
-}
-
-/*
- * searches a range in the state tree for a given mask.
- * If 'filled' == 1, this returns 1 only if ever extent in the tree
- * has the bits set.  Otherwise, 1 is returned if any bit in the
- * range is found set.
- */
-int test_range_bit(struct extent_map_tree *tree, u64 start, u64 end,
-		   int bits, int filled)
-{
-	struct extent_state *state = NULL;
-	struct rb_node *node;
-	int bitset = 0;
-
-	read_lock_irq(&tree->lock);
-	node = tree_search(&tree->state, start);
-	while (node && start <= end) {
-		state = rb_entry(node, struct extent_state, rb_node);
-
-		if (filled && state->start > start) {
-			bitset = 0;
-			break;
-		}
-
-		if (state->start > end)
-			break;
-
-		if (state->state & bits) {
-			bitset = 1;
-			if (!filled)
-				break;
-		} else if (filled) {
-			bitset = 0;
-			break;
-		}
-		start = state->end + 1;
-		if (start > end)
-			break;
-		node = rb_next(node);
-		if (!node) {
-			if (filled)
-				bitset = 0;
-			break;
-		}
-	}
-	read_unlock_irq(&tree->lock);
-	return bitset;
-}
-EXPORT_SYMBOL(test_range_bit);
-
-/*
- * helper function to set a given page up to date if all the
- * extents in the tree for that page are up to date
- */
-static int check_page_uptodate(struct extent_map_tree *tree,
-			       struct page *page)
-{
-	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
-	u64 end = start + PAGE_CACHE_SIZE - 1;
-	if (test_range_bit(tree, start, end, EXTENT_UPTODATE, 1))
-		SetPageUptodate(page);
-	return 0;
-}
-
-/*
- * helper function to unlock a page if all the extents in the tree
- * for that page are unlocked
- */
-static int check_page_locked(struct extent_map_tree *tree,
-			     struct page *page)
-{
-	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
-	u64 end = start + PAGE_CACHE_SIZE - 1;
-	if (!test_range_bit(tree, start, end, EXTENT_LOCKED, 0))
-		unlock_page(page);
-	return 0;
-}
-
-/*
- * helper function to end page writeback if all the extents
- * in the tree for that page are done with writeback
- */
-static int check_page_writeback(struct extent_map_tree *tree,
-			     struct page *page)
-{
-	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
-	u64 end = start + PAGE_CACHE_SIZE - 1;
-	if (!test_range_bit(tree, start, end, EXTENT_WRITEBACK, 0))
-		end_page_writeback(page);
-	return 0;
-}
-
-/* lots and lots of room for performance fixes in the end_bio funcs */
-
-/*
- * after a writepage IO is done, we need to:
- * clear the uptodate bits on error
- * clear the writeback bits in the extent tree for this IO
- * end_page_writeback if the page has no more pending IO
- *
- * Scheduling is not allowed, so the extent state tree is expected
- * to have one and only one object corresponding to this IO.
- */
-#if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
-static void end_bio_extent_writepage(struct bio *bio, int err)
-#else
-static int end_bio_extent_writepage(struct bio *bio,
-				   unsigned int bytes_done, int err)
-#endif
-{
-	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
-	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
-	struct extent_map_tree *tree = bio->bi_private;
-	u64 start;
-	u64 end;
-	int whole_page;
-
-#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
-	if (bio->bi_size)
-		return 1;
-#endif
-
-	do {
-		struct page *page = bvec->bv_page;
-		start = ((u64)page->index << PAGE_CACHE_SHIFT) +
-			 bvec->bv_offset;
-		end = start + bvec->bv_len - 1;
-
-		if (bvec->bv_offset == 0 && bvec->bv_len == PAGE_CACHE_SIZE)
-			whole_page = 1;
-		else
-			whole_page = 0;
-
-		if (--bvec >= bio->bi_io_vec)
-			prefetchw(&bvec->bv_page->flags);
-
-		if (!uptodate) {
-			clear_extent_uptodate(tree, start, end, GFP_ATOMIC);
-			ClearPageUptodate(page);
-			SetPageError(page);
-		}
-		clear_extent_writeback(tree, start, end, GFP_ATOMIC);
-
-		if (whole_page)
-			end_page_writeback(page);
-		else
-			check_page_writeback(tree, page);
-		if (tree->ops && tree->ops->writepage_end_io_hook)
-			tree->ops->writepage_end_io_hook(page, start, end);
-	} while (bvec >= bio->bi_io_vec);
-
-	bio_put(bio);
-#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
-	return 0;
-#endif
-}
-
-/*
- * after a readpage IO is done, we need to:
- * clear the uptodate bits on error
- * set the uptodate bits if things worked
- * set the page up to date if all extents in the tree are uptodate
- * clear the lock bit in the extent tree
- * unlock the page if there are no other extents locked for it
- *
- * Scheduling is not allowed, so the extent state tree is expected
- * to have one and only one object corresponding to this IO.
- */
-#if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
-static void end_bio_extent_readpage(struct bio *bio, int err)
-#else
-static int end_bio_extent_readpage(struct bio *bio,
-				   unsigned int bytes_done, int err)
-#endif
-{
-	int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
-	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
-	struct extent_map_tree *tree = bio->bi_private;
-	u64 start;
-	u64 end;
-	int whole_page;
-	int ret;
-
-#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
-	if (bio->bi_size)
-		return 1;
-#endif
-
-	do {
-		struct page *page = bvec->bv_page;
-		start = ((u64)page->index << PAGE_CACHE_SHIFT) +
-			bvec->bv_offset;
-		end = start + bvec->bv_len - 1;
-
-		if (bvec->bv_offset == 0 && bvec->bv_len == PAGE_CACHE_SIZE)
-			whole_page = 1;
-		else
-			whole_page = 0;
-
-		if (--bvec >= bio->bi_io_vec)
-			prefetchw(&bvec->bv_page->flags);
-
-		if (uptodate && tree->ops && tree->ops->readpage_end_io_hook) {
-			ret = tree->ops->readpage_end_io_hook(page, start, end);
-			if (ret)
-				uptodate = 0;
-		}
-		if (uptodate) {
-			set_extent_uptodate(tree, start, end, GFP_ATOMIC);
-			if (whole_page)
-				SetPageUptodate(page);
-			else
-				check_page_uptodate(tree, page);
-		} else {
-			ClearPageUptodate(page);
-			SetPageError(page);
-		}
-
-		unlock_extent(tree, start, end, GFP_ATOMIC);
-
-		if (whole_page)
-			unlock_page(page);
-		else
-			check_page_locked(tree, page);
-	} while (bvec >= bio->bi_io_vec);
-
-	bio_put(bio);
-#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
-	return 0;
-#endif
-}
-
-/*
- * IO done from prepare_write is pretty simple, we just unlock
- * the structs in the extent tree when done, and set the uptodate bits
- * as appropriate.
- */
-#if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,23)
-static void end_bio_extent_preparewrite(struct bio *bio, int err)
-#else
-static int end_bio_extent_preparewrite(struct bio *bio,
-				       unsigned int bytes_done, int err)
-#endif
-{
-	const int uptodate = test_bit(BIO_UPTODATE, &bio->bi_flags);
-	struct bio_vec *bvec = bio->bi_io_vec + bio->bi_vcnt - 1;
-	struct extent_map_tree *tree = bio->bi_private;
-	u64 start;
-	u64 end;
-
-#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
-	if (bio->bi_size)
-		return 1;
-#endif
-
-	do {
-		struct page *page = bvec->bv_page;
-		start = ((u64)page->index << PAGE_CACHE_SHIFT) +
-			bvec->bv_offset;
-		end = start + bvec->bv_len - 1;
-
-		if (--bvec >= bio->bi_io_vec)
-			prefetchw(&bvec->bv_page->flags);
-
-		if (uptodate) {
-			set_extent_uptodate(tree, start, end, GFP_ATOMIC);
-		} else {
-			ClearPageUptodate(page);
-			SetPageError(page);
-		}
-
-		unlock_extent(tree, start, end, GFP_ATOMIC);
-
-	} while (bvec >= bio->bi_io_vec);
-
-	bio_put(bio);
-#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
-	return 0;
-#endif
-}
-
-static struct bio *
-extent_bio_alloc(struct block_device *bdev, u64 first_sector, int nr_vecs,
-		 gfp_t gfp_flags)
-{
-	struct bio *bio;
-
-	bio = bio_alloc(gfp_flags, nr_vecs);
-
-	if (bio == NULL && (current->flags & PF_MEMALLOC)) {
-		while (!bio && (nr_vecs /= 2))
-			bio = bio_alloc(gfp_flags, nr_vecs);
-	}
-
-	if (bio) {
-		bio->bi_bdev = bdev;
-		bio->bi_sector = first_sector;
-	}
-	return bio;
-}
-
-static int submit_one_bio(int rw, struct bio *bio)
-{
-	u64 maxsector;
-	int ret = 0;
-
-	bio_get(bio);
-
-        maxsector = bio->bi_bdev->bd_inode->i_size >> 9;
-	if (maxsector < bio->bi_sector) {
-		printk("sector too large max %Lu got %llu\n", maxsector,
-			(unsigned long long)bio->bi_sector);
-		WARN_ON(1);
-	}
-
-	submit_bio(rw, bio);
-	if (bio_flagged(bio, BIO_EOPNOTSUPP))
-		ret = -EOPNOTSUPP;
-	bio_put(bio);
-	return ret;
-}
-
-static int submit_extent_page(int rw, struct extent_map_tree *tree,
-			      struct page *page, sector_t sector,
-			      size_t size, unsigned long offset,
-			      struct block_device *bdev,
-			      struct bio **bio_ret,
-			      unsigned long max_pages,
-			      bio_end_io_t end_io_func)
-{
-	int ret = 0;
-	struct bio *bio;
-	int nr;
-
-	if (bio_ret && *bio_ret) {
-		bio = *bio_ret;
-		if (bio->bi_sector + (bio->bi_size >> 9) != sector ||
-		    bio_add_page(bio, page, size, offset) < size) {
-			ret = submit_one_bio(rw, bio);
-			bio = NULL;
-		} else {
-			return 0;
-		}
-	}
-	nr = min_t(int, max_pages, bio_get_nr_vecs(bdev));
-	bio = extent_bio_alloc(bdev, sector, nr, GFP_NOFS | __GFP_HIGH);
-	if (!bio) {
-		printk("failed to allocate bio nr %d\n", nr);
-	}
-	bio_add_page(bio, page, size, offset);
-	bio->bi_end_io = end_io_func;
-	bio->bi_private = tree;
-	if (bio_ret) {
-		*bio_ret = bio;
-	} else {
-		ret = submit_one_bio(rw, bio);
-	}
-
-	return ret;
-}
-
-void set_page_extent_mapped(struct page *page)
-{
-	if (!PagePrivate(page)) {
-		SetPagePrivate(page);
-		WARN_ON(!page->mapping->a_ops->invalidatepage);
-		set_page_private(page, EXTENT_PAGE_PRIVATE);
-		page_cache_get(page);
-	}
-}
-
-void set_page_extent_head(struct page *page, unsigned long len)
-{
-	set_page_private(page, EXTENT_PAGE_PRIVATE_FIRST_PAGE | len << 2);
-}
-
-/*
- * basic readpage implementation.  Locked extent state structs are inserted
- * into the tree that are removed when the IO is done (by the end_io
- * handlers)
- */
-static int __extent_read_full_page(struct extent_map_tree *tree,
-				   struct page *page,
-				   get_extent_t *get_extent,
-				   struct bio **bio)
-{
-	struct inode *inode = page->mapping->host;
-	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
-	u64 page_end = start + PAGE_CACHE_SIZE - 1;
-	u64 end;
-	u64 cur = start;
-	u64 extent_offset;
-	u64 last_byte = i_size_read(inode);
-	u64 block_start;
-	u64 cur_end;
-	sector_t sector;
-	struct extent_map *em;
-	struct block_device *bdev;
-	int ret;
-	int nr = 0;
-	size_t page_offset = 0;
-	size_t iosize;
-	size_t blocksize = inode->i_sb->s_blocksize;
-
-	set_page_extent_mapped(page);
-
-	end = page_end;
-	lock_extent(tree, start, end, GFP_NOFS);
-
-	while (cur <= end) {
-		if (cur >= last_byte) {
-			char *userpage;
-			iosize = PAGE_CACHE_SIZE - page_offset;
-			userpage = kmap_atomic(page, KM_USER0);
-			memset(userpage + page_offset, 0, iosize);
-			flush_dcache_page(page);
-			kunmap_atomic(userpage, KM_USER0);
-			set_extent_uptodate(tree, cur, cur + iosize - 1,
-					    GFP_NOFS);
-			unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
-			break;
-		}
-		em = get_extent(inode, page, page_offset, cur, end, 0);
-		if (IS_ERR(em) || !em) {
-			SetPageError(page);
-			unlock_extent(tree, cur, end, GFP_NOFS);
-			break;
-		}
-
-		extent_offset = cur - em->start;
-		BUG_ON(em->end < cur);
-		BUG_ON(end < cur);
-
-		iosize = min(em->end - cur, end - cur) + 1;
-		cur_end = min(em->end, end);
-		iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1);
-		sector = (em->block_start + extent_offset) >> 9;
-		bdev = em->bdev;
-		block_start = em->block_start;
-		free_extent_map(em);
-		em = NULL;
-
-		/* we've found a hole, just zero and go on */
-		if (block_start == EXTENT_MAP_HOLE) {
-			char *userpage;
-			userpage = kmap_atomic(page, KM_USER0);
-			memset(userpage + page_offset, 0, iosize);
-			flush_dcache_page(page);
-			kunmap_atomic(userpage, KM_USER0);
-
-			set_extent_uptodate(tree, cur, cur + iosize - 1,
-					    GFP_NOFS);
-			unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
-			cur = cur + iosize;
-			page_offset += iosize;
-			continue;
-		}
-		/* the get_extent function already copied into the page */
-		if (test_range_bit(tree, cur, cur_end, EXTENT_UPTODATE, 1)) {
-			unlock_extent(tree, cur, cur + iosize - 1, GFP_NOFS);
-			cur = cur + iosize;
-			page_offset += iosize;
-			continue;
-		}
-
-		ret = 0;
-		if (tree->ops && tree->ops->readpage_io_hook) {
-			ret = tree->ops->readpage_io_hook(page, cur,
-							  cur + iosize - 1);
-		}
-		if (!ret) {
-			unsigned long nr = (last_byte >> PAGE_CACHE_SHIFT) + 1;
-			nr -= page->index;
-			ret = submit_extent_page(READ, tree, page,
-					 sector, iosize, page_offset,
-					 bdev, bio, nr,
-					 end_bio_extent_readpage);
-		}
-		if (ret)
-			SetPageError(page);
-		cur = cur + iosize;
-		page_offset += iosize;
-		nr++;
-	}
-	if (!nr) {
-		if (!PageError(page))
-			SetPageUptodate(page);
-		unlock_page(page);
-	}
-	return 0;
-}
-
-int extent_read_full_page(struct extent_map_tree *tree, struct page *page,
-			    get_extent_t *get_extent)
-{
-	struct bio *bio = NULL;
-	int ret;
-
-	ret = __extent_read_full_page(tree, page, get_extent, &bio);
-	if (bio)
-		submit_one_bio(READ, bio);
-	return ret;
-}
-EXPORT_SYMBOL(extent_read_full_page);
-
-/*
- * the writepage semantics are similar to regular writepage.  extent
- * records are inserted to lock ranges in the tree, and as dirty areas
- * are found, they are marked writeback.  Then the lock bits are removed
- * and the end_io handler clears the writeback ranges
- */
-static int __extent_writepage(struct page *page, struct writeback_control *wbc,
-			      void *data)
-{
-	struct inode *inode = page->mapping->host;
-	struct extent_page_data *epd = data;
-	struct extent_map_tree *tree = epd->tree;
-	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
-	u64 delalloc_start;
-	u64 page_end = start + PAGE_CACHE_SIZE - 1;
-	u64 end;
-	u64 cur = start;
-	u64 extent_offset;
-	u64 last_byte = i_size_read(inode);
-	u64 block_start;
-	u64 iosize;
-	sector_t sector;
-	struct extent_map *em;
-	struct block_device *bdev;
-	int ret;
-	int nr = 0;
-	size_t page_offset = 0;
-	size_t blocksize;
-	loff_t i_size = i_size_read(inode);
-	unsigned long end_index = i_size >> PAGE_CACHE_SHIFT;
-	u64 nr_delalloc;
-	u64 delalloc_end;
-
-	WARN_ON(!PageLocked(page));
-	if (page->index > end_index) {
-		clear_extent_dirty(tree, start, page_end, GFP_NOFS);
-		unlock_page(page);
-		return 0;
-	}
-
-	if (page->index == end_index) {
-		char *userpage;
-
-		size_t offset = i_size & (PAGE_CACHE_SIZE - 1);
-
-		userpage = kmap_atomic(page, KM_USER0);
-		memset(userpage + offset, 0, PAGE_CACHE_SIZE - offset);
-		flush_dcache_page(page);
-		kunmap_atomic(userpage, KM_USER0);
-	}
-
-	set_page_extent_mapped(page);
-
-	delalloc_start = start;
-	delalloc_end = 0;
-	while(delalloc_end < page_end) {
-		nr_delalloc = find_lock_delalloc_range(tree, &delalloc_start,
-						       &delalloc_end,
-						       128 * 1024 * 1024);
-		if (nr_delalloc == 0) {
-			delalloc_start = delalloc_end + 1;
-			continue;
-		}
-		tree->ops->fill_delalloc(inode, delalloc_start,
-					 delalloc_end);
-		clear_extent_bit(tree, delalloc_start,
-				 delalloc_end,
-				 EXTENT_LOCKED | EXTENT_DELALLOC,
-				 1, 0, GFP_NOFS);
-		delalloc_start = delalloc_end + 1;
-	}
-	lock_extent(tree, start, page_end, GFP_NOFS);
-
-	end = page_end;
-	if (test_range_bit(tree, start, page_end, EXTENT_DELALLOC, 0)) {
-		printk("found delalloc bits after lock_extent\n");
-	}
-
-	if (last_byte <= start) {
-		clear_extent_dirty(tree, start, page_end, GFP_NOFS);
-		goto done;
-	}
-
-	set_extent_uptodate(tree, start, page_end, GFP_NOFS);
-	blocksize = inode->i_sb->s_blocksize;
-
-	while (cur <= end) {
-		if (cur >= last_byte) {
-			clear_extent_dirty(tree, cur, page_end, GFP_NOFS);
-			break;
-		}
-		em = epd->get_extent(inode, page, page_offset, cur, end, 1);
-		if (IS_ERR(em) || !em) {
-			SetPageError(page);
-			break;
-		}
-
-		extent_offset = cur - em->start;
-		BUG_ON(em->end < cur);
-		BUG_ON(end < cur);
-		iosize = min(em->end - cur, end - cur) + 1;
-		iosize = (iosize + blocksize - 1) & ~((u64)blocksize - 1);
-		sector = (em->block_start + extent_offset) >> 9;
-		bdev = em->bdev;
-		block_start = em->block_start;
-		free_extent_map(em);
-		em = NULL;
-
-		if (block_start == EXTENT_MAP_HOLE ||
-		    block_start == EXTENT_MAP_INLINE) {
-			clear_extent_dirty(tree, cur,
-					   cur + iosize - 1, GFP_NOFS);
-			cur = cur + iosize;
-			page_offset += iosize;
-			continue;
-		}
-
-		/* leave this out until we have a page_mkwrite call */
-		if (0 && !test_range_bit(tree, cur, cur + iosize - 1,
-				   EXTENT_DIRTY, 0)) {
-			cur = cur + iosize;
-			page_offset += iosize;
-			continue;
-		}
-		clear_extent_dirty(tree, cur, cur + iosize - 1, GFP_NOFS);
-		if (tree->ops && tree->ops->writepage_io_hook) {
-			ret = tree->ops->writepage_io_hook(page, cur,
-						cur + iosize - 1);
-		} else {
-			ret = 0;
-		}
-		if (ret)
-			SetPageError(page);
-		else {
-			unsigned long max_nr = end_index + 1;
-			set_range_writeback(tree, cur, cur + iosize - 1);
-			if (!PageWriteback(page)) {
-				printk("warning page %lu not writeback, "
-				       "cur %llu end %llu\n", page->index,
-				       (unsigned long long)cur,
-				       (unsigned long long)end);
-			}
-
-			ret = submit_extent_page(WRITE, tree, page, sector,
-						 iosize, page_offset, bdev,
-						 &epd->bio, max_nr,
-						 end_bio_extent_writepage);
-			if (ret)
-				SetPageError(page);
-		}
-		cur = cur + iosize;
-		page_offset += iosize;
-		nr++;
-	}
-done:
-	if (nr == 0) {
-		/* make sure the mapping tag for page dirty gets cleared */
-		set_page_writeback(page);
-		end_page_writeback(page);
-	}
-	unlock_extent(tree, start, page_end, GFP_NOFS);
-	unlock_page(page);
-	return 0;
-}
-
-#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,18)
-
-/* Taken directly from 2.6.23 for 2.6.18 back port */
-typedef int (*writepage_t)(struct page *page, struct writeback_control *wbc,
-                                void *data);
-
-/**
- * write_cache_pages - walk the list of dirty pages of the given address space
- * and write all of them.
- * @mapping: address space structure to write
- * @wbc: subtract the number of written pages from *@wbc->nr_to_write
- * @writepage: function called for each page
- * @data: data passed to writepage function
- *
- * If a page is already under I/O, write_cache_pages() skips it, even
- * if it's dirty.  This is desirable behaviour for memory-cleaning writeback,
- * but it is INCORRECT for data-integrity system calls such as fsync().  fsync()
- * and msync() need to guarantee that all the data which was dirty at the time
- * the call was made get new I/O started against them.  If wbc->sync_mode is
- * WB_SYNC_ALL then we were called for data integrity and we must wait for
- * existing IO to complete.
- */
-static int write_cache_pages(struct address_space *mapping,
-		      struct writeback_control *wbc, writepage_t writepage,
-		      void *data)
-{
-	struct backing_dev_info *bdi = mapping->backing_dev_info;
-	int ret = 0;
-	int done = 0;
-	struct pagevec pvec;
-	int nr_pages;
-	pgoff_t index;
-	pgoff_t end;		/* Inclusive */
-	int scanned = 0;
-	int range_whole = 0;
-
-	if (wbc->nonblocking && bdi_write_congested(bdi)) {
-		wbc->encountered_congestion = 1;
-		return 0;
-	}
-
-	pagevec_init(&pvec, 0);
-	if (wbc->range_cyclic) {
-		index = mapping->writeback_index; /* Start from prev offset */
-		end = -1;
-	} else {
-		index = wbc->range_start >> PAGE_CACHE_SHIFT;
-		end = wbc->range_end >> PAGE_CACHE_SHIFT;
-		if (wbc->range_start == 0 && wbc->range_end == LLONG_MAX)
-			range_whole = 1;
-		scanned = 1;
-	}
-retry:
-	while (!done && (index <= end) &&
-	       (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
-					      PAGECACHE_TAG_DIRTY,
-					      min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1))) {
-		unsigned i;
-
-		scanned = 1;
-		for (i = 0; i < nr_pages; i++) {
-			struct page *page = pvec.pages[i];
-
-			/*
-			 * At this point we hold neither mapping->tree_lock nor
-			 * lock on the page itself: the page may be truncated or
-			 * invalidated (changing page->mapping to NULL), or even
-			 * swizzled back from swapper_space to tmpfs file
-			 * mapping
-			 */
-			lock_page(page);
-
-			if (unlikely(page->mapping != mapping)) {
-				unlock_page(page);
-				continue;
-			}
-
-			if (!wbc->range_cyclic && page->index > end) {
-				done = 1;
-				unlock_page(page);
-				continue;
-			}
-
-			if (wbc->sync_mode != WB_SYNC_NONE)
-				wait_on_page_writeback(page);
-
-			if (PageWriteback(page) ||
-			    !clear_page_dirty_for_io(page)) {
-				unlock_page(page);
-				continue;
-			}
-
-			ret = (*writepage)(page, wbc, data);
-
-			if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE)) {
-				unlock_page(page);
-				ret = 0;
-			}
-			if (ret || (--(wbc->nr_to_write) <= 0))
-				done = 1;
-			if (wbc->nonblocking && bdi_write_congested(bdi)) {
-				wbc->encountered_congestion = 1;
-				done = 1;
-			}
-		}
-		pagevec_release(&pvec);
-		cond_resched();
-	}
-	if (!scanned && !done) {
-		/*
-		 * We hit the last page and there is more work to be done: wrap
-		 * back to the start of the file
-		 */
-		scanned = 1;
-		index = 0;
-		goto retry;
-	}
-	if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
-		mapping->writeback_index = index;
-	return ret;
-}
-#endif
-
-int extent_write_full_page(struct extent_map_tree *tree, struct page *page,
-			  get_extent_t *get_extent,
-			  struct writeback_control *wbc)
-{
-	int ret;
-	struct address_space *mapping = page->mapping;
-	struct extent_page_data epd = {
-		.bio = NULL,
-		.tree = tree,
-		.get_extent = get_extent,
-	};
-	struct writeback_control wbc_writepages = {
-		.bdi		= wbc->bdi,
-		.sync_mode	= WB_SYNC_NONE,
-		.older_than_this = NULL,
-		.nr_to_write	= 64,
-		.range_start	= page_offset(page) + PAGE_CACHE_SIZE,
-		.range_end	= (loff_t)-1,
-	};
-
-
-	ret = __extent_writepage(page, wbc, &epd);
-
-	write_cache_pages(mapping, &wbc_writepages, __extent_writepage, &epd);
-	if (epd.bio) {
-		submit_one_bio(WRITE, epd.bio);
-	}
-	return ret;
-}
-EXPORT_SYMBOL(extent_write_full_page);
-
-
-int extent_writepages(struct extent_map_tree *tree,
-		      struct address_space *mapping,
-		      get_extent_t *get_extent,
-		      struct writeback_control *wbc)
-{
 	int ret = 0;
-	struct extent_page_data epd = {
-		.bio = NULL,
-		.tree = tree,
-		.get_extent = get_extent,
-	};
-
-	ret = write_cache_pages(mapping, wbc, __extent_writepage, &epd);
-	if (epd.bio) {
-		submit_one_bio(WRITE, epd.bio);
-	}
-	return ret;
-}
-EXPORT_SYMBOL(extent_writepages);
-
-int extent_readpages(struct extent_map_tree *tree,
-		     struct address_space *mapping,
-		     struct list_head *pages, unsigned nr_pages,
-		     get_extent_t get_extent)
-{
-	struct bio *bio = NULL;
-	unsigned page_idx;
-	struct pagevec pvec;
-
-	pagevec_init(&pvec, 0);
-	for (page_idx = 0; page_idx < nr_pages; page_idx++) {
-		struct page *page = list_entry(pages->prev, struct page, lru);
-
-		prefetchw(&page->flags);
-		list_del(&page->lru);
-		/*
-		 * what we want to do here is call add_to_page_cache_lru,
-		 * but that isn't exported, so we reproduce it here
-		 */
-		if (!add_to_page_cache(page, mapping,
-					page->index, GFP_KERNEL)) {
-
-			/* open coding of lru_cache_add, also not exported */
-			page_cache_get(page);
-			if (!pagevec_add(&pvec, page))
-				__pagevec_lru_add(&pvec);
-			__extent_read_full_page(tree, page, get_extent, &bio);
-		}
-		page_cache_release(page);
-	}
-	if (pagevec_count(&pvec))
-		__pagevec_lru_add(&pvec);
-	BUG_ON(!list_empty(pages));
-	if (bio)
-		submit_one_bio(READ, bio);
-	return 0;
-}
-EXPORT_SYMBOL(extent_readpages);
-
-/*
- * basic invalidatepage code, this waits on any locked or writeback
- * ranges corresponding to the page, and then deletes any extent state
- * records from the tree
- */
-int extent_invalidatepage(struct extent_map_tree *tree,
-			  struct page *page, unsigned long offset)
-{
-	u64 start = ((u64)page->index << PAGE_CACHE_SHIFT);
-	u64 end = start + PAGE_CACHE_SIZE - 1;
-	size_t blocksize = page->mapping->host->i_sb->s_blocksize;
-
-	start += (offset + blocksize -1) & ~(blocksize - 1);
-	if (start > end)
-		return 0;
-
-	lock_extent(tree, start, end, GFP_NOFS);
-	wait_on_extent_writeback(tree, start, end);
-	clear_extent_bit(tree, start, end,
-			 EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC,
-			 1, 1, GFP_NOFS);
-	return 0;
-}
-EXPORT_SYMBOL(extent_invalidatepage);
-
-/*
- * simple commit_write call, set_range_dirty is used to mark both
- * the pages and the extent records as dirty
- */
-int extent_commit_write(struct extent_map_tree *tree,
-			struct inode *inode, struct page *page,
-			unsigned from, unsigned to)
-{
-	loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
-
-	set_page_extent_mapped(page);
-	set_page_dirty(page);
-
-	if (pos > inode->i_size) {
-		i_size_write(inode, pos);
-		mark_inode_dirty(inode);
-	}
-	return 0;
-}
-EXPORT_SYMBOL(extent_commit_write);
-
-int extent_prepare_write(struct extent_map_tree *tree,
-			 struct inode *inode, struct page *page,
-			 unsigned from, unsigned to, get_extent_t *get_extent)
-{
-	u64 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
-	u64 page_end = page_start + PAGE_CACHE_SIZE - 1;
-	u64 block_start;
-	u64 orig_block_start;
-	u64 block_end;
-	u64 cur_end;
-	struct extent_map *em;
-	unsigned blocksize = 1 << inode->i_blkbits;
-	size_t page_offset = 0;
-	size_t block_off_start;
-	size_t block_off_end;
-	int err = 0;
-	int iocount = 0;
-	int ret = 0;
-	int isnew;
-
-	set_page_extent_mapped(page);
-
-	block_start = (page_start + from) & ~((u64)blocksize - 1);
-	block_end = (page_start + to - 1) | (blocksize - 1);
-	orig_block_start = block_start;
-
-	lock_extent(tree, page_start, page_end, GFP_NOFS);
-	while(block_start <= block_end) {
-		em = get_extent(inode, page, page_offset, block_start,
-				block_end, 1);
-		if (IS_ERR(em) || !em) {
-			goto err;
-		}
-		cur_end = min(block_end, em->end);
-		block_off_start = block_start & (PAGE_CACHE_SIZE - 1);
-		block_off_end = block_off_start + blocksize;
-		isnew = clear_extent_new(tree, block_start, cur_end, GFP_NOFS);
-
-		if (!PageUptodate(page) && isnew &&
-		    (block_off_end > to || block_off_start < from)) {
-			void *kaddr;
-
-			kaddr = kmap_atomic(page, KM_USER0);
-			if (block_off_end > to)
-				memset(kaddr + to, 0, block_off_end - to);
-			if (block_off_start < from)
-				memset(kaddr + block_off_start, 0,
-				       from - block_off_start);
-			flush_dcache_page(page);
-			kunmap_atomic(kaddr, KM_USER0);
-		}
-		if ((em->block_start != EXTENT_MAP_HOLE &&
-		     em->block_start != EXTENT_MAP_INLINE) &&
-		    !isnew && !PageUptodate(page) &&
-		    (block_off_end > to || block_off_start < from) &&
-		    !test_range_bit(tree, block_start, cur_end,
-				    EXTENT_UPTODATE, 1)) {
-			u64 sector;
-			u64 extent_offset = block_start - em->start;
-			size_t iosize;
-			sector = (em->block_start + extent_offset) >> 9;
-			iosize = (cur_end - block_start + blocksize) &
-				~((u64)blocksize - 1);
-			/*
-			 * we've already got the extent locked, but we
-			 * need to split the state such that our end_bio
-			 * handler can clear the lock.
-			 */
-			set_extent_bit(tree, block_start,
-				       block_start + iosize - 1,
-				       EXTENT_LOCKED, 0, NULL, GFP_NOFS);
-			ret = submit_extent_page(READ, tree, page,
-					 sector, iosize, page_offset, em->bdev,
-					 NULL, 1,
-					 end_bio_extent_preparewrite);
-			iocount++;
-			block_start = block_start + iosize;
-		} else {
-			set_extent_uptodate(tree, block_start, cur_end,
-					    GFP_NOFS);
-			unlock_extent(tree, block_start, cur_end, GFP_NOFS);
-			block_start = cur_end + 1;
-		}
-		page_offset = block_start & (PAGE_CACHE_SIZE - 1);
-		free_extent_map(em);
-	}
-	if (iocount) {
-		wait_extent_bit(tree, orig_block_start,
-				block_end, EXTENT_LOCKED);
-	}
-	check_page_uptodate(tree, page);
-err:
-	/* FIXME, zero out newly allocated blocks on error */
-	return err;
-}
-EXPORT_SYMBOL(extent_prepare_write);
-
-/*
- * a helper for releasepage.  As long as there are no locked extents
- * in the range corresponding to the page, both state records and extent
- * map records are removed
- */
-int try_release_extent_mapping(struct extent_map_tree *tree, struct page *page)
-{
-	struct extent_map *em;
-	u64 start = (u64)page->index << PAGE_CACHE_SHIFT;
-	u64 end = start + PAGE_CACHE_SIZE - 1;
-	u64 orig_start = start;
-	int ret = 1;
-
-	while (start <= end) {
-		em = lookup_extent_mapping(tree, start, end);
-		if (!em || IS_ERR(em))
-			break;
-		if (!test_range_bit(tree, em->start, em->end,
-				    EXTENT_LOCKED, 0)) {
-			remove_extent_mapping(tree, em);
-			/* once for the rb tree */
-			free_extent_map(em);
-		}
-		start = em->end + 1;
-		/* once for us */
-		free_extent_map(em);
-	}
-	if (test_range_bit(tree, orig_start, end, EXTENT_LOCKED, 0))
-		ret = 0;
-	else
-		clear_extent_bit(tree, orig_start, end, EXTENT_UPTODATE,
-				 1, 1, GFP_NOFS);
-	return ret;
-}
-EXPORT_SYMBOL(try_release_extent_mapping);
-
-sector_t extent_bmap(struct address_space *mapping, sector_t iblock,
-		get_extent_t *get_extent)
-{
-	struct inode *inode = mapping->host;
-	u64 start = iblock << inode->i_blkbits;
-	u64 end = start + (1 << inode->i_blkbits) - 1;
-	sector_t sector = 0;
-	struct extent_map *em;
-
-	em = get_extent(inode, NULL, 0, start, end, 0);
-	if (!em || IS_ERR(em))
-		return 0;
-
-	if (em->block_start == EXTENT_MAP_INLINE ||
-	    em->block_start == EXTENT_MAP_HOLE)
-		goto out;
-
-	sector = (em->block_start + start - em->start) >> inode->i_blkbits;
-out:
-	free_extent_map(em);
-	return sector;
-}
-
-static int add_lru(struct extent_map_tree *tree, struct extent_buffer *eb)
-{
-	if (list_empty(&eb->lru)) {
-		extent_buffer_get(eb);
-		list_add(&eb->lru, &tree->buffer_lru);
-		tree->lru_size++;
-		if (tree->lru_size >= BUFFER_LRU_MAX) {
-			struct extent_buffer *rm;
-			rm = list_entry(tree->buffer_lru.prev,
-					struct extent_buffer, lru);
-			tree->lru_size--;
-			list_del_init(&rm->lru);
-			free_extent_buffer(rm);
-		}
-	} else
-		list_move(&eb->lru, &tree->buffer_lru);
-	return 0;
-}
-static struct extent_buffer *find_lru(struct extent_map_tree *tree,
-				      u64 start, unsigned long len)
-{
-	struct list_head *lru = &tree->buffer_lru;
-	struct list_head *cur = lru->next;
-	struct extent_buffer *eb;
-
-	if (list_empty(lru))
-		return NULL;
-
-	do {
-		eb = list_entry(cur, struct extent_buffer, lru);
-		if (eb->start == start && eb->len == len) {
-			extent_buffer_get(eb);
-			return eb;
-		}
-		cur = cur->next;
-	} while (cur != lru);
-	return NULL;
-}
-
-static inline unsigned long num_extent_pages(u64 start, u64 len)
-{
-	return ((start + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT) -
-		(start >> PAGE_CACHE_SHIFT);
-}
-
-static inline struct page *extent_buffer_page(struct extent_buffer *eb,
-					      unsigned long i)
-{
-	struct page *p;
-	struct address_space *mapping;
-
-	if (i == 0)
-		return eb->first_page;
-	i += eb->start >> PAGE_CACHE_SHIFT;
-	mapping = eb->first_page->mapping;
-	read_lock_irq(&mapping->tree_lock);
-	p = radix_tree_lookup(&mapping->page_tree, i);
-	read_unlock_irq(&mapping->tree_lock);
-	return p;
-}
-
-static struct extent_buffer *__alloc_extent_buffer(struct extent_map_tree *tree,
-						   u64 start,
-						   unsigned long len,
-						   gfp_t mask)
-{
-	struct extent_buffer *eb = NULL;
 
-	spin_lock(&tree->lru_lock);
-	eb = find_lru(tree, start, len);
-	spin_unlock(&tree->lru_lock);
-	if (eb) {
-		return eb;
-	}
-
-	eb = kmem_cache_zalloc(extent_buffer_cache, mask);
-	INIT_LIST_HEAD(&eb->lru);
-	eb->start = start;
-	eb->len = len;
-	atomic_set(&eb->refs, 1);
-
-	return eb;
-}
-
-static void __free_extent_buffer(struct extent_buffer *eb)
-{
-	kmem_cache_free(extent_buffer_cache, eb);
-}
-
-struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
-					  u64 start, unsigned long len,
-					  struct page *page0,
-					  gfp_t mask)
-{
-	unsigned long num_pages = num_extent_pages(start, len);
-	unsigned long i;
-	unsigned long index = start >> PAGE_CACHE_SHIFT;
-	struct extent_buffer *eb;
-	struct page *p;
-	struct address_space *mapping = tree->mapping;
-	int uptodate = 1;
-
-	eb = __alloc_extent_buffer(tree, start, len, mask);
-	if (!eb || IS_ERR(eb))
-		return NULL;
-
-	if (eb->flags & EXTENT_BUFFER_FILLED)
-		goto lru_add;
-
-	if (page0) {
-		eb->first_page = page0;
-		i = 1;
-		index++;
-		page_cache_get(page0);
-		mark_page_accessed(page0);
-		set_page_extent_mapped(page0);
-		WARN_ON(!PageUptodate(page0));
-		set_page_extent_head(page0, len);
-	} else {
-		i = 0;
-	}
-	for (; i < num_pages; i++, index++) {
-		p = find_or_create_page(mapping, index, mask | __GFP_HIGHMEM);
-		if (!p) {
-			WARN_ON(1);
-			goto fail;
-		}
-		set_page_extent_mapped(p);
-		mark_page_accessed(p);
-		if (i == 0) {
-			eb->first_page = p;
-			set_page_extent_head(p, len);
-		} else {
-			set_page_private(p, EXTENT_PAGE_PRIVATE);
-		}
-		if (!PageUptodate(p))
-			uptodate = 0;
-		unlock_page(p);
-	}
-	if (uptodate)
-		eb->flags |= EXTENT_UPTODATE;
-	eb->flags |= EXTENT_BUFFER_FILLED;
-
-lru_add:
-	spin_lock(&tree->lru_lock);
-	add_lru(tree, eb);
-	spin_unlock(&tree->lru_lock);
-	return eb;
-
-fail:
-	spin_lock(&tree->lru_lock);
-	list_del_init(&eb->lru);
-	spin_unlock(&tree->lru_lock);
-	if (!atomic_dec_and_test(&eb->refs))
-		return NULL;
-	for (index = 1; index < i; index++) {
-		page_cache_release(extent_buffer_page(eb, index));
-	}
-	if (i > 0)
-		page_cache_release(extent_buffer_page(eb, 0));
-	__free_extent_buffer(eb);
-	return NULL;
-}
-EXPORT_SYMBOL(alloc_extent_buffer);
-
-struct extent_buffer *find_extent_buffer(struct extent_map_tree *tree,
-					 u64 start, unsigned long len,
-					  gfp_t mask)
-{
-	unsigned long num_pages = num_extent_pages(start, len);
-	unsigned long i;
-	unsigned long index = start >> PAGE_CACHE_SHIFT;
-	struct extent_buffer *eb;
-	struct page *p;
-	struct address_space *mapping = tree->mapping;
-	int uptodate = 1;
-
-	eb = __alloc_extent_buffer(tree, start, len, mask);
-	if (!eb || IS_ERR(eb))
-		return NULL;
-
-	if (eb->flags & EXTENT_BUFFER_FILLED)
-		goto lru_add;
-
-	for (i = 0; i < num_pages; i++, index++) {
-		p = find_lock_page(mapping, index);
-		if (!p) {
-			goto fail;
-		}
-		set_page_extent_mapped(p);
-		mark_page_accessed(p);
-
-		if (i == 0) {
-			eb->first_page = p;
-			set_page_extent_head(p, len);
-		} else {
-			set_page_private(p, EXTENT_PAGE_PRIVATE);
-		}
-
-		if (!PageUptodate(p))
-			uptodate = 0;
-		unlock_page(p);
-	}
-	if (uptodate)
-		eb->flags |= EXTENT_UPTODATE;
-	eb->flags |= EXTENT_BUFFER_FILLED;
-
-lru_add:
-	spin_lock(&tree->lru_lock);
-	add_lru(tree, eb);
-	spin_unlock(&tree->lru_lock);
-	return eb;
-fail:
-	spin_lock(&tree->lru_lock);
-	list_del_init(&eb->lru);
-	spin_unlock(&tree->lru_lock);
-	if (!atomic_dec_and_test(&eb->refs))
-		return NULL;
-	for (index = 1; index < i; index++) {
-		page_cache_release(extent_buffer_page(eb, index));
-	}
-	if (i > 0)
-		page_cache_release(extent_buffer_page(eb, 0));
-	__free_extent_buffer(eb);
-	return NULL;
-}
-EXPORT_SYMBOL(find_extent_buffer);
-
-void free_extent_buffer(struct extent_buffer *eb)
-{
-	unsigned long i;
-	unsigned long num_pages;
-
-	if (!eb)
-		return;
-
-	if (!atomic_dec_and_test(&eb->refs))
-		return;
-
-	WARN_ON(!list_empty(&eb->lru));
-	num_pages = num_extent_pages(eb->start, eb->len);
-
-	for (i = 1; i < num_pages; i++) {
-		page_cache_release(extent_buffer_page(eb, i));
-	}
-	page_cache_release(extent_buffer_page(eb, 0));
-	__free_extent_buffer(eb);
-}
-EXPORT_SYMBOL(free_extent_buffer);
-
-int clear_extent_buffer_dirty(struct extent_map_tree *tree,
-			      struct extent_buffer *eb)
-{
-	int set;
-	unsigned long i;
-	unsigned long num_pages;
-	struct page *page;
-
-	u64 start = eb->start;
-	u64 end = start + eb->len - 1;
-
-	set = clear_extent_dirty(tree, start, end, GFP_NOFS);
-	num_pages = num_extent_pages(eb->start, eb->len);
-
-	for (i = 0; i < num_pages; i++) {
-		page = extent_buffer_page(eb, i);
-		lock_page(page);
-		if (i == 0)
-			set_page_extent_head(page, eb->len);
-		else
-			set_page_private(page, EXTENT_PAGE_PRIVATE);
-
-		/*
-		 * if we're on the last page or the first page and the
-		 * block isn't aligned on a page boundary, do extra checks
-		 * to make sure we don't clean page that is partially dirty
-		 */
-		if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) ||
-		    ((i == num_pages - 1) &&
-		     ((eb->start + eb->len) & (PAGE_CACHE_SIZE - 1)))) {
-			start = (u64)page->index << PAGE_CACHE_SHIFT;
-			end  = start + PAGE_CACHE_SIZE - 1;
-			if (test_range_bit(tree, start, end,
-					   EXTENT_DIRTY, 0)) {
-				unlock_page(page);
-				continue;
-			}
-		}
-		clear_page_dirty_for_io(page);
-		write_lock_irq(&page->mapping->tree_lock);
-		if (!PageDirty(page)) {
-			radix_tree_tag_clear(&page->mapping->page_tree,
-						page_index(page),
-						PAGECACHE_TAG_DIRTY);
-		}
-		write_unlock_irq(&page->mapping->tree_lock);
-		unlock_page(page);
-	}
-	return 0;
-}
-EXPORT_SYMBOL(clear_extent_buffer_dirty);
-
-int wait_on_extent_buffer_writeback(struct extent_map_tree *tree,
-				    struct extent_buffer *eb)
-{
-	return wait_on_extent_writeback(tree, eb->start,
-					eb->start + eb->len - 1);
-}
-EXPORT_SYMBOL(wait_on_extent_buffer_writeback);
-
-int set_extent_buffer_dirty(struct extent_map_tree *tree,
-			     struct extent_buffer *eb)
-{
-	unsigned long i;
-	unsigned long num_pages;
-
-	num_pages = num_extent_pages(eb->start, eb->len);
-	for (i = 0; i < num_pages; i++) {
-		struct page *page = extent_buffer_page(eb, i);
-		/* writepage may need to do something special for the
-		 * first page, we have to make sure page->private is
-		 * properly set.  releasepage may drop page->private
-		 * on us if the page isn't already dirty.
-		 */
-		if (i == 0) {
-			lock_page(page);
-			set_page_extent_head(page, eb->len);
-		} else if (PagePrivate(page) &&
-			   page->private != EXTENT_PAGE_PRIVATE) {
-			lock_page(page);
-			set_page_extent_mapped(page);
-			unlock_page(page);
-		}
-		__set_page_dirty_nobuffers(extent_buffer_page(eb, i));
-		if (i == 0)
-			unlock_page(page);
-	}
-	return set_extent_dirty(tree, eb->start,
-				eb->start + eb->len - 1, GFP_NOFS);
-}
-EXPORT_SYMBOL(set_extent_buffer_dirty);
-
-int set_extent_buffer_uptodate(struct extent_map_tree *tree,
-				struct extent_buffer *eb)
-{
-	unsigned long i;
-	struct page *page;
-	unsigned long num_pages;
-
-	num_pages = num_extent_pages(eb->start, eb->len);
-
-	set_extent_uptodate(tree, eb->start, eb->start + eb->len - 1,
-			    GFP_NOFS);
-	for (i = 0; i < num_pages; i++) {
-		page = extent_buffer_page(eb, i);
-		if ((i == 0 && (eb->start & (PAGE_CACHE_SIZE - 1))) ||
-		    ((i == num_pages - 1) &&
-		     ((eb->start + eb->len) & (PAGE_CACHE_SIZE - 1)))) {
-			check_page_uptodate(tree, page);
-			continue;
-		}
-		SetPageUptodate(page);
-	}
-	return 0;
-}
-EXPORT_SYMBOL(set_extent_buffer_uptodate);
-
-int extent_buffer_uptodate(struct extent_map_tree *tree,
-			     struct extent_buffer *eb)
-{
-	if (eb->flags & EXTENT_UPTODATE)
-		return 1;
-	return test_range_bit(tree, eb->start, eb->start + eb->len - 1,
-			   EXTENT_UPTODATE, 1);
-}
-EXPORT_SYMBOL(extent_buffer_uptodate);
-
-int read_extent_buffer_pages(struct extent_map_tree *tree,
-			     struct extent_buffer *eb,
-			     u64 start,
-			     int wait)
-{
-	unsigned long i;
-	unsigned long start_i;
-	struct page *page;
-	int err;
-	int ret = 0;
-	unsigned long num_pages;
-
-	if (eb->flags & EXTENT_UPTODATE)
-		return 0;
-
-	if (0 && test_range_bit(tree, eb->start, eb->start + eb->len - 1,
-			   EXTENT_UPTODATE, 1)) {
-		return 0;
-	}
-
-	if (start) {
-		WARN_ON(start < eb->start);
-		start_i = (start >> PAGE_CACHE_SHIFT) -
-			(eb->start >> PAGE_CACHE_SHIFT);
-	} else {
-		start_i = 0;
-	}
-
-	num_pages = num_extent_pages(eb->start, eb->len);
-	for (i = start_i; i < num_pages; i++) {
-		page = extent_buffer_page(eb, i);
-		if (PageUptodate(page)) {
-			continue;
-		}
-		if (!wait) {
-			if (TestSetPageLocked(page)) {
-				continue;
-			}
-		} else {
-			lock_page(page);
-		}
-		if (!PageUptodate(page)) {
-			err = page->mapping->a_ops->readpage(NULL, page);
-			if (err) {
-				ret = err;
-			}
-		} else {
-			unlock_page(page);
-		}
-	}
-
-	if (ret || !wait) {
-		return ret;
-	}
-
-	for (i = start_i; i < num_pages; i++) {
-		page = extent_buffer_page(eb, i);
-		wait_on_page_locked(page);
-		if (!PageUptodate(page)) {
-			ret = -EIO;
-		}
-	}
-	if (!ret)
-		eb->flags |= EXTENT_UPTODATE;
-	return ret;
-}
-EXPORT_SYMBOL(read_extent_buffer_pages);
-
-void read_extent_buffer(struct extent_buffer *eb, void *dstv,
-			unsigned long start,
-			unsigned long len)
-{
-	size_t cur;
-	size_t offset;
-	struct page *page;
-	char *kaddr;
-	char *dst = (char *)dstv;
-	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
-	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
-	unsigned long num_pages = num_extent_pages(eb->start, eb->len);
-
-	WARN_ON(start > eb->len);
-	WARN_ON(start + len > eb->start + eb->len);
-
-	offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
-
-	while(len > 0) {
-		page = extent_buffer_page(eb, i);
-		if (!PageUptodate(page)) {
-			printk("page %lu not up to date i %lu, total %lu, len %lu\n", page->index, i, num_pages, eb->len);
-			WARN_ON(1);
-		}
-		WARN_ON(!PageUptodate(page));
-
-		cur = min(len, (PAGE_CACHE_SIZE - offset));
-		kaddr = kmap_atomic(page, KM_USER1);
-		memcpy(dst, kaddr + offset, cur);
-		kunmap_atomic(kaddr, KM_USER1);
-
-		dst += cur;
-		len -= cur;
-		offset = 0;
-		i++;
-	}
-}
-EXPORT_SYMBOL(read_extent_buffer);
-
-int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
-			       unsigned long min_len, char **token, char **map,
-			       unsigned long *map_start,
-			       unsigned long *map_len, int km)
-{
-	size_t offset = start & (PAGE_CACHE_SIZE - 1);
-	char *kaddr;
-	struct page *p;
-	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
-	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
-	unsigned long end_i = (start_offset + start + min_len - 1) >>
-		PAGE_CACHE_SHIFT;
-
-	if (i != end_i)
-		return -EINVAL;
-
-	if (i == 0) {
-		offset = start_offset;
-		*map_start = 0;
-	} else {
-		offset = 0;
-		*map_start = ((u64)i << PAGE_CACHE_SHIFT) - start_offset;
-	}
-	if (start + min_len > eb->len) {
-printk("bad mapping eb start %Lu len %lu, wanted %lu %lu\n", eb->start, eb->len, start, min_len);
-		WARN_ON(1);
-	}
-
-	p = extent_buffer_page(eb, i);
-	WARN_ON(!PageUptodate(p));
-	kaddr = kmap_atomic(p, km);
-	*token = kaddr;
-	*map = kaddr + offset;
-	*map_len = PAGE_CACHE_SIZE - offset;
-	return 0;
-}
-EXPORT_SYMBOL(map_private_extent_buffer);
-
-int map_extent_buffer(struct extent_buffer *eb, unsigned long start,
-		      unsigned long min_len,
-		      char **token, char **map,
-		      unsigned long *map_start,
-		      unsigned long *map_len, int km)
-{
-	int err;
-	int save = 0;
-	if (eb->map_token) {
-		unmap_extent_buffer(eb, eb->map_token, km);
-		eb->map_token = NULL;
-		save = 1;
-	}
-	err = map_private_extent_buffer(eb, start, min_len, token, map,
-				       map_start, map_len, km);
-	if (!err && save) {
-		eb->map_token = *token;
-		eb->kaddr = *map;
-		eb->map_start = *map_start;
-		eb->map_len = *map_len;
-	}
-	return err;
-}
-EXPORT_SYMBOL(map_extent_buffer);
-
-void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km)
-{
-	kunmap_atomic(token, km);
-}
-EXPORT_SYMBOL(unmap_extent_buffer);
-
-int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
-			  unsigned long start,
-			  unsigned long len)
-{
-	size_t cur;
-	size_t offset;
-	struct page *page;
-	char *kaddr;
-	char *ptr = (char *)ptrv;
-	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
-	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
-	int ret = 0;
-
-	WARN_ON(start > eb->len);
-	WARN_ON(start + len > eb->start + eb->len);
-
-	offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
-
-	while(len > 0) {
-		page = extent_buffer_page(eb, i);
-		WARN_ON(!PageUptodate(page));
-
-		cur = min(len, (PAGE_CACHE_SIZE - offset));
-
-		kaddr = kmap_atomic(page, KM_USER0);
-		ret = memcmp(ptr, kaddr + offset, cur);
-		kunmap_atomic(kaddr, KM_USER0);
-		if (ret)
-			break;
-
-		ptr += cur;
-		len -= cur;
-		offset = 0;
-		i++;
-	}
+	rb_erase(&em->rb_node, &tree->map);
+	em->in_tree = 0;
+	if (tree->last == em)
+		tree->last = NULL;
 	return ret;
 }
-EXPORT_SYMBOL(memcmp_extent_buffer);
-
-void write_extent_buffer(struct extent_buffer *eb, const void *srcv,
-			 unsigned long start, unsigned long len)
-{
-	size_t cur;
-	size_t offset;
-	struct page *page;
-	char *kaddr;
-	char *src = (char *)srcv;
-	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
-	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
-
-	WARN_ON(start > eb->len);
-	WARN_ON(start + len > eb->start + eb->len);
-
-	offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
-
-	while(len > 0) {
-		page = extent_buffer_page(eb, i);
-		WARN_ON(!PageUptodate(page));
-
-		cur = min(len, PAGE_CACHE_SIZE - offset);
-		kaddr = kmap_atomic(page, KM_USER1);
-		memcpy(kaddr + offset, src, cur);
-		kunmap_atomic(kaddr, KM_USER1);
-
-		src += cur;
-		len -= cur;
-		offset = 0;
-		i++;
-	}
-}
-EXPORT_SYMBOL(write_extent_buffer);
-
-void memset_extent_buffer(struct extent_buffer *eb, char c,
-			  unsigned long start, unsigned long len)
-{
-	size_t cur;
-	size_t offset;
-	struct page *page;
-	char *kaddr;
-	size_t start_offset = eb->start & ((u64)PAGE_CACHE_SIZE - 1);
-	unsigned long i = (start_offset + start) >> PAGE_CACHE_SHIFT;
-
-	WARN_ON(start > eb->len);
-	WARN_ON(start + len > eb->start + eb->len);
-
-	offset = (start_offset + start) & ((unsigned long)PAGE_CACHE_SIZE - 1);
-
-	while(len > 0) {
-		page = extent_buffer_page(eb, i);
-		WARN_ON(!PageUptodate(page));
-
-		cur = min(len, PAGE_CACHE_SIZE - offset);
-		kaddr = kmap_atomic(page, KM_USER0);
-		memset(kaddr + offset, c, cur);
-		kunmap_atomic(kaddr, KM_USER0);
-
-		len -= cur;
-		offset = 0;
-		i++;
-	}
-}
-EXPORT_SYMBOL(memset_extent_buffer);
-
-void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
-			unsigned long dst_offset, unsigned long src_offset,
-			unsigned long len)
-{
-	u64 dst_len = dst->len;
-	size_t cur;
-	size_t offset;
-	struct page *page;
-	char *kaddr;
-	size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
-	unsigned long i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
-
-	WARN_ON(src->len != dst_len);
-
-	offset = (start_offset + dst_offset) &
-		((unsigned long)PAGE_CACHE_SIZE - 1);
-
-	while(len > 0) {
-		page = extent_buffer_page(dst, i);
-		WARN_ON(!PageUptodate(page));
-
-		cur = min(len, (unsigned long)(PAGE_CACHE_SIZE - offset));
-
-		kaddr = kmap_atomic(page, KM_USER0);
-		read_extent_buffer(src, kaddr + offset, src_offset, cur);
-		kunmap_atomic(kaddr, KM_USER0);
-
-		src_offset += cur;
-		len -= cur;
-		offset = 0;
-		i++;
-	}
-}
-EXPORT_SYMBOL(copy_extent_buffer);
-
-static void move_pages(struct page *dst_page, struct page *src_page,
-		       unsigned long dst_off, unsigned long src_off,
-		       unsigned long len)
-{
-	char *dst_kaddr = kmap_atomic(dst_page, KM_USER0);
-	if (dst_page == src_page) {
-		memmove(dst_kaddr + dst_off, dst_kaddr + src_off, len);
-	} else {
-		char *src_kaddr = kmap_atomic(src_page, KM_USER1);
-		char *p = dst_kaddr + dst_off + len;
-		char *s = src_kaddr + src_off + len;
-
-		while (len--)
-			*--p = *--s;
-
-		kunmap_atomic(src_kaddr, KM_USER1);
-	}
-	kunmap_atomic(dst_kaddr, KM_USER0);
-}
-
-static void copy_pages(struct page *dst_page, struct page *src_page,
-		       unsigned long dst_off, unsigned long src_off,
-		       unsigned long len)
-{
-	char *dst_kaddr = kmap_atomic(dst_page, KM_USER0);
-	char *src_kaddr;
-
-	if (dst_page != src_page)
-		src_kaddr = kmap_atomic(src_page, KM_USER1);
-	else
-		src_kaddr = dst_kaddr;
-
-	memcpy(dst_kaddr + dst_off, src_kaddr + src_off, len);
-	kunmap_atomic(dst_kaddr, KM_USER0);
-	if (dst_page != src_page)
-		kunmap_atomic(src_kaddr, KM_USER1);
-}
-
-void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
-			   unsigned long src_offset, unsigned long len)
-{
-	size_t cur;
-	size_t dst_off_in_page;
-	size_t src_off_in_page;
-	size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
-	unsigned long dst_i;
-	unsigned long src_i;
-
-	if (src_offset + len > dst->len) {
-		printk("memmove bogus src_offset %lu move len %lu len %lu\n",
-		       src_offset, len, dst->len);
-		BUG_ON(1);
-	}
-	if (dst_offset + len > dst->len) {
-		printk("memmove bogus dst_offset %lu move len %lu len %lu\n",
-		       dst_offset, len, dst->len);
-		BUG_ON(1);
-	}
-
-	while(len > 0) {
-		dst_off_in_page = (start_offset + dst_offset) &
-			((unsigned long)PAGE_CACHE_SIZE - 1);
-		src_off_in_page = (start_offset + src_offset) &
-			((unsigned long)PAGE_CACHE_SIZE - 1);
-
-		dst_i = (start_offset + dst_offset) >> PAGE_CACHE_SHIFT;
-		src_i = (start_offset + src_offset) >> PAGE_CACHE_SHIFT;
-
-		cur = min(len, (unsigned long)(PAGE_CACHE_SIZE -
-					       src_off_in_page));
-		cur = min_t(unsigned long, cur,
-			(unsigned long)(PAGE_CACHE_SIZE - dst_off_in_page));
-
-		copy_pages(extent_buffer_page(dst, dst_i),
-			   extent_buffer_page(dst, src_i),
-			   dst_off_in_page, src_off_in_page, cur);
-
-		src_offset += cur;
-		dst_offset += cur;
-		len -= cur;
-	}
-}
-EXPORT_SYMBOL(memcpy_extent_buffer);
-
-void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
-			   unsigned long src_offset, unsigned long len)
-{
-	size_t cur;
-	size_t dst_off_in_page;
-	size_t src_off_in_page;
-	unsigned long dst_end = dst_offset + len - 1;
-	unsigned long src_end = src_offset + len - 1;
-	size_t start_offset = dst->start & ((u64)PAGE_CACHE_SIZE - 1);
-	unsigned long dst_i;
-	unsigned long src_i;
-
-	if (src_offset + len > dst->len) {
-		printk("memmove bogus src_offset %lu move len %lu len %lu\n",
-		       src_offset, len, dst->len);
-		BUG_ON(1);
-	}
-	if (dst_offset + len > dst->len) {
-		printk("memmove bogus dst_offset %lu move len %lu len %lu\n",
-		       dst_offset, len, dst->len);
-		BUG_ON(1);
-	}
-	if (dst_offset < src_offset) {
-		memcpy_extent_buffer(dst, dst_offset, src_offset, len);
-		return;
-	}
-	while(len > 0) {
-		dst_i = (start_offset + dst_end) >> PAGE_CACHE_SHIFT;
-		src_i = (start_offset + src_end) >> PAGE_CACHE_SHIFT;
-
-		dst_off_in_page = (start_offset + dst_end) &
-			((unsigned long)PAGE_CACHE_SIZE - 1);
-		src_off_in_page = (start_offset + src_end) &
-			((unsigned long)PAGE_CACHE_SIZE - 1);
-
-		cur = min_t(unsigned long, len, src_off_in_page + 1);
-		cur = min(cur, dst_off_in_page + 1);
-		move_pages(extent_buffer_page(dst, dst_i),
-			   extent_buffer_page(dst, src_i),
-			   dst_off_in_page - cur + 1,
-			   src_off_in_page - cur + 1, cur);
-
-		dst_end -= cur;
-		src_end -= cur;
-		len -= cur;
-	}
-}
-EXPORT_SYMBOL(memmove_extent_buffer);
+EXPORT_SYMBOL(remove_extent_mapping);
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index ea60f54..56314217 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -3,215 +3,53 @@
 
 #include <linux/rbtree.h>
 
+#define EXTENT_MAP_LAST_BYTE (u64)-4
 #define EXTENT_MAP_HOLE (u64)-3
 #define EXTENT_MAP_INLINE (u64)-2
 #define EXTENT_MAP_DELALLOC (u64)-1
 
-/* bits for the extent state */
-#define EXTENT_DIRTY 1
-#define EXTENT_WRITEBACK (1 << 1)
-#define EXTENT_UPTODATE (1 << 2)
-#define EXTENT_LOCKED (1 << 3)
-#define EXTENT_NEW (1 << 4)
-#define EXTENT_DELALLOC (1 << 5)
-#define EXTENT_DEFRAG (1 << 6)
-#define EXTENT_DEFRAG_DONE (1 << 7)
-#define EXTENT_BUFFER_FILLED (1 << 8)
-#define EXTENT_CSUM (1 << 9)
-#define EXTENT_IOBITS (EXTENT_LOCKED | EXTENT_WRITEBACK)
-
-/*
- * page->private values.  Every page that is controlled by the extent
- * map has page->private set to one.
- */
-#define EXTENT_PAGE_PRIVATE 1
-#define EXTENT_PAGE_PRIVATE_FIRST_PAGE 3
-
-
-struct extent_map_ops {
-	int (*fill_delalloc)(struct inode *inode, u64 start, u64 end);
-	int (*writepage_io_hook)(struct page *page, u64 start, u64 end);
-	int (*readpage_io_hook)(struct page *page, u64 start, u64 end);
-	int (*readpage_end_io_hook)(struct page *page, u64 start, u64 end);
-	void (*writepage_end_io_hook)(struct page *page, u64 start, u64 end);
-};
-
-struct extent_map_tree {
-	struct rb_root map;
-	struct rb_root state;
-	struct address_space *mapping;
-	u64 dirty_bytes;
-	rwlock_t lock;
-	struct extent_map_ops *ops;
-	spinlock_t lru_lock;
-	struct list_head buffer_lru;
-	int lru_size;
-};
-
-/* note, this must start with the same fields as fs/extent_map.c:tree_entry */
 struct extent_map {
-	u64 start;
-	u64 end; /* inclusive */
-	int in_tree;
 	struct rb_node rb_node;
-	/* block_start and block_end are in bytes */
+
+	/* all of these are in bytes */
+	u64 start;
+	u64 len;
 	u64 block_start;
-	u64 block_end; /* inclusive */
+	unsigned long flags;
 	struct block_device *bdev;
 	atomic_t refs;
-};
-
-/* note, this must start with the same fields as fs/extent_map.c:tree_entry */
-struct extent_state {
-	u64 start;
-	u64 end; /* inclusive */
 	int in_tree;
-	struct rb_node rb_node;
-	wait_queue_head_t wq;
-	atomic_t refs;
-	unsigned long state;
-
-	/* for use by the FS */
-	u64 private;
-
-	struct list_head list;
 };
 
-struct extent_buffer {
-	u64 start;
-	unsigned long len;
-	char *map_token;
-	char *kaddr;
-	unsigned long map_start;
-	unsigned long map_len;
-	struct page *first_page;
-	struct list_head lru;
-	atomic_t refs;
-	int flags;
+struct extent_map_tree {
+	struct rb_root map;
+	struct extent_map *last;
+	spinlock_t lock;
 };
 
-typedef struct extent_map *(get_extent_t)(struct inode *inode,
-					  struct page *page,
-					  size_t page_offset,
-					  u64 start, u64 end,
-					  int create);
+static inline u64 extent_map_end(struct extent_map *em)
+{
+	if (em->start + em->len < em->start)
+		return (u64)-1;
+	return em->start + em->len;
+}
+
+static inline u64 extent_map_block_end(struct extent_map *em)
+{
+	if (em->block_start + em->len < em->block_start)
+		return (u64)-1;
+	return em->block_start + em->len;
+}
 
-void extent_map_tree_init(struct extent_map_tree *tree,
-			  struct address_space *mapping, gfp_t mask);
-void extent_map_tree_empty_lru(struct extent_map_tree *tree);
+void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask);
 struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
-					 u64 start, u64 end);
+					 u64 start, u64 len);
 int add_extent_mapping(struct extent_map_tree *tree,
 		       struct extent_map *em);
 int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em);
-int try_release_extent_mapping(struct extent_map_tree *tree, struct page *page);
-int lock_extent(struct extent_map_tree *tree, u64 start, u64 end, gfp_t mask);
-int unlock_extent(struct extent_map_tree *tree, u64 start, u64 end, gfp_t mask);
+
 struct extent_map *alloc_extent_map(gfp_t mask);
 void free_extent_map(struct extent_map *em);
-int extent_read_full_page(struct extent_map_tree *tree, struct page *page,
-			  get_extent_t *get_extent);
 int __init extent_map_init(void);
 void extent_map_exit(void);
-
-u64 count_range_bits(struct extent_map_tree *tree,
-		     u64 *start, u64 search_end,
-		     u64 max_bytes, unsigned long bits);
-
-int test_range_bit(struct extent_map_tree *tree, u64 start, u64 end,
-		   int bits, int filled);
-int clear_extent_bits(struct extent_map_tree *tree, u64 start, u64 end,
-		      int bits, gfp_t mask);
-int set_extent_bits(struct extent_map_tree *tree, u64 start, u64 end,
-		    int bits, gfp_t mask);
-int set_extent_uptodate(struct extent_map_tree *tree, u64 start, u64 end,
-			gfp_t mask);
-int set_extent_new(struct extent_map_tree *tree, u64 start, u64 end,
-		   gfp_t mask);
-int set_extent_dirty(struct extent_map_tree *tree, u64 start, u64 end,
-		     gfp_t mask);
-int clear_extent_dirty(struct extent_map_tree *tree, u64 start, u64 end,
-		       gfp_t mask);
-int set_extent_delalloc(struct extent_map_tree *tree, u64 start, u64 end,
-		     gfp_t mask);
-int find_first_extent_bit(struct extent_map_tree *tree, u64 start,
-			  u64 *start_ret, u64 *end_ret, int bits);
-int extent_invalidatepage(struct extent_map_tree *tree,
-			  struct page *page, unsigned long offset);
-int extent_write_full_page(struct extent_map_tree *tree, struct page *page,
-			  get_extent_t *get_extent,
-			  struct writeback_control *wbc);
-int extent_writepages(struct extent_map_tree *tree,
-		      struct address_space *mapping,
-		      get_extent_t *get_extent,
-		      struct writeback_control *wbc);
-int extent_readpages(struct extent_map_tree *tree,
-		     struct address_space *mapping,
-		     struct list_head *pages, unsigned nr_pages,
-		     get_extent_t get_extent);
-int extent_prepare_write(struct extent_map_tree *tree,
-			 struct inode *inode, struct page *page,
-			 unsigned from, unsigned to, get_extent_t *get_extent);
-int extent_commit_write(struct extent_map_tree *tree,
-			struct inode *inode, struct page *page,
-			unsigned from, unsigned to);
-sector_t extent_bmap(struct address_space *mapping, sector_t iblock,
-		get_extent_t *get_extent);
-int set_range_dirty(struct extent_map_tree *tree, u64 start, u64 end);
-int set_state_private(struct extent_map_tree *tree, u64 start, u64 private);
-int get_state_private(struct extent_map_tree *tree, u64 start, u64 *private);
-void set_page_extent_mapped(struct page *page);
-
-struct extent_buffer *alloc_extent_buffer(struct extent_map_tree *tree,
-					  u64 start, unsigned long len,
-					  struct page *page0,
-					  gfp_t mask);
-struct extent_buffer *find_extent_buffer(struct extent_map_tree *tree,
-					 u64 start, unsigned long len,
-					  gfp_t mask);
-void free_extent_buffer(struct extent_buffer *eb);
-int read_extent_buffer_pages(struct extent_map_tree *tree,
-			     struct extent_buffer *eb, u64 start, int wait);
-
-static inline void extent_buffer_get(struct extent_buffer *eb)
-{
-	atomic_inc(&eb->refs);
-}
-
-int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
-			  unsigned long start,
-			  unsigned long len);
-void read_extent_buffer(struct extent_buffer *eb, void *dst,
-			unsigned long start,
-			unsigned long len);
-void write_extent_buffer(struct extent_buffer *eb, const void *src,
-			 unsigned long start, unsigned long len);
-void copy_extent_buffer(struct extent_buffer *dst, struct extent_buffer *src,
-			unsigned long dst_offset, unsigned long src_offset,
-			unsigned long len);
-void memcpy_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
-			   unsigned long src_offset, unsigned long len);
-void memmove_extent_buffer(struct extent_buffer *dst, unsigned long dst_offset,
-			   unsigned long src_offset, unsigned long len);
-void memset_extent_buffer(struct extent_buffer *eb, char c,
-			  unsigned long start, unsigned long len);
-int wait_on_extent_buffer_writeback(struct extent_map_tree *tree,
-				    struct extent_buffer *eb);
-int clear_extent_buffer_dirty(struct extent_map_tree *tree,
-			      struct extent_buffer *eb);
-int set_extent_buffer_dirty(struct extent_map_tree *tree,
-			     struct extent_buffer *eb);
-int set_extent_buffer_uptodate(struct extent_map_tree *tree,
-			       struct extent_buffer *eb);
-int extent_buffer_uptodate(struct extent_map_tree *tree,
-			   struct extent_buffer *eb);
-int map_extent_buffer(struct extent_buffer *eb, unsigned long offset,
-		      unsigned long min_len, char **token, char **map,
-		      unsigned long *map_start,
-		      unsigned long *map_len, int km);
-int map_private_extent_buffer(struct extent_buffer *eb, unsigned long offset,
-		      unsigned long min_len, char **token, char **map,
-		      unsigned long *map_start,
-		      unsigned long *map_len, int km);
-void unmap_extent_buffer(struct extent_buffer *eb, char *token, int km);
 #endif
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 1cd8c90..c5bb00f 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -233,8 +233,7 @@ static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
 	int err = 0;
 	int i;
 	struct inode *inode = fdentry(file)->d_inode;
-	struct extent_map *em;
-	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	u64 hint_byte;
 	u64 num_bytes;
 	u64 start_pos;
@@ -242,11 +241,6 @@ static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
 	u64 end_pos = pos + write_bytes;
 	u64 inline_size;
 	loff_t isize = i_size_read(inode);
-	em = alloc_extent_map(GFP_NOFS);
-	if (!em)
-		return -ENOMEM;
-
-	em->bdev = inode->i_sb->s_bdev;
 
 	start_pos = pos & ~((u64)root->sectorsize - 1);
 	num_bytes = (write_bytes + pos - start_pos +
@@ -254,7 +248,7 @@ static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
 
 	end_of_last_block = start_pos + num_bytes - 1;
 
-	lock_extent(em_tree, start_pos, end_of_last_block, GFP_NOFS);
+	lock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 	mutex_lock(&root->fs_info->fs_mutex);
 	trans = btrfs_start_transaction(root, 1);
 	if (!trans) {
@@ -268,7 +262,7 @@ static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
 	if ((end_of_last_block & 4095) == 0) {
 		printk("strange end of last %Lu %zu %Lu\n", start_pos, write_bytes, end_of_last_block);
 	}
-	set_extent_uptodate(em_tree, start_pos, end_of_last_block, GFP_NOFS);
+	set_extent_uptodate(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 
 	/* FIXME...EIEIO, ENOSPC and more */
 
@@ -293,6 +287,8 @@ static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
 						       inode->i_ino,
 						       last_pos_in_file,
 						       0, 0, hole_size);
+			btrfs_drop_extent_cache(inode, last_pos_in_file,
+					last_pos_in_file + hole_size -1);
 			btrfs_check_file(root, inode);
 		}
 		if (err)
@@ -320,12 +316,12 @@ static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
 		last_end += PAGE_CACHE_SIZE - 1;
 		if (start_pos < isize) {
 			u64 delalloc_start = start_pos;
-			existing_delalloc = count_range_bits(em_tree,
+			existing_delalloc = count_range_bits(io_tree,
 					     &delalloc_start,
 					     end_of_last_block, (u64)-1,
 					     EXTENT_DELALLOC);
 		}
-		set_extent_delalloc(em_tree, start_pos, end_of_last_block,
+		set_extent_delalloc(io_tree, start_pos, end_of_last_block,
 				 GFP_NOFS);
 		spin_lock(&root->fs_info->delalloc_lock);
 		root->fs_info->delalloc_bytes += (end_of_last_block + 1 -
@@ -346,6 +342,7 @@ static int noinline dirty_and_release_pages(struct btrfs_trans_handle *trans,
 		inline_size -= start_pos;
 		err = insert_inline_extent(trans, root, inode, start_pos,
 					   inline_size, pages, 0, num_pages);
+		btrfs_drop_extent_cache(inode, start_pos, aligned_end - 1);
 		BUG_ON(err);
 	}
 	if (end_pos > isize) {
@@ -356,8 +353,7 @@ failed:
 	err = btrfs_end_transaction(trans, root);
 out_unlock:
 	mutex_unlock(&root->fs_info->fs_mutex);
-	unlock_extent(em_tree, start_pos, end_of_last_block, GFP_NOFS);
-	free_extent_map(em);
+	unlock_extent(io_tree, start_pos, end_of_last_block, GFP_NOFS);
 	return err;
 }
 
@@ -367,10 +363,15 @@ int btrfs_drop_extent_cache(struct inode *inode, u64 start, u64 end)
 	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
 
 	while(1) {
+		spin_lock(&em_tree->lock);
 		em = lookup_extent_mapping(em_tree, start, end);
-		if (!em)
+		if (!em) {
+			spin_unlock(&em_tree->lock);
 			break;
+		}
 		remove_extent_mapping(em_tree, em);
+		spin_unlock(&em_tree->lock);
+
 		/* once for us */
 		free_extent_map(em);
 		/* once for the tree*/
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 67005480..16d3aef 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -53,7 +53,7 @@ static struct inode_operations btrfs_file_inode_operations;
 static struct address_space_operations btrfs_aops;
 static struct address_space_operations btrfs_symlink_aops;
 static struct file_operations btrfs_dir_file_operations;
-static struct extent_map_ops btrfs_extent_map_ops;
+static struct extent_io_ops btrfs_extent_io_ops;
 
 static struct kmem_cache *btrfs_inode_cachep;
 struct kmem_cache *btrfs_trans_handle_cachep;
@@ -104,6 +104,8 @@ static int cow_file_range(struct inode *inode, u64 start, u64 end)
 	u64 num_bytes;
 	u64 cur_alloc_size;
 	u64 blocksize = root->sectorsize;
+	u64 orig_start = start;
+	u64 orig_num_bytes;
 	struct btrfs_key ins;
 	int ret;
 
@@ -115,6 +117,7 @@ static int cow_file_range(struct inode *inode, u64 start, u64 end)
 	num_bytes = max(blocksize,  num_bytes);
 	ret = btrfs_drop_extents(trans, root, inode,
 				 start, start + num_bytes, start, &alloc_hint);
+	orig_num_bytes = num_bytes;
 
 	if (alloc_hint == EXTENT_MAP_INLINE)
 		goto out;
@@ -138,6 +141,8 @@ static int cow_file_range(struct inode *inode, u64 start, u64 end)
 		alloc_hint = ins.objectid + ins.offset;
 		start += cur_alloc_size;
 	}
+	btrfs_drop_extent_cache(inode, orig_start,
+				orig_start + orig_num_bytes - 1);
 	btrfs_add_ordered_inode(inode);
 out:
 	btrfs_end_transaction(trans, root);
@@ -297,7 +302,7 @@ int btrfs_readpage_io_hook(struct page *page, u64 start, u64 end)
 	int ret = 0;
 	struct inode *inode = page->mapping->host;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
-	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	struct btrfs_csum_item *item;
 	struct btrfs_path *path = NULL;
 	u32 csum;
@@ -317,7 +322,7 @@ int btrfs_readpage_io_hook(struct page *page, u64 start, u64 end)
 	}
 	read_extent_buffer(path->nodes[0], &csum, (unsigned long)item,
 			   BTRFS_CRC32_SIZE);
-	set_state_private(em_tree, start, csum);
+	set_state_private(io_tree, start, csum);
 out:
 	if (path)
 		btrfs_free_path(path);
@@ -329,17 +334,19 @@ int btrfs_readpage_end_io_hook(struct page *page, u64 start, u64 end)
 {
 	size_t offset = start - ((u64)page->index << PAGE_CACHE_SHIFT);
 	struct inode *inode = page->mapping->host;
-	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	char *kaddr;
 	u64 private;
 	int ret;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	u32 csum = ~(u32)0;
 	unsigned long flags;
+
 	if (btrfs_test_opt(root, NODATASUM) ||
 	    btrfs_test_flag(inode, NODATASUM))
 		return 0;
-	ret = get_state_private(em_tree, start, &private);
+
+	ret = get_state_private(io_tree, start, &private);
 	local_irq_save(flags);
 	kaddr = kmap_atomic(page, KM_IRQ0);
 	if (ret) {
@@ -428,7 +435,7 @@ void btrfs_read_locked_inode(struct inode *inode)
 	switch (inode->i_mode & S_IFMT) {
 	case S_IFREG:
 		inode->i_mapping->a_ops = &btrfs_aops;
-		BTRFS_I(inode)->extent_tree.ops = &btrfs_extent_map_ops;
+		BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
 		inode->i_fop = &btrfs_file_operations;
 		inode->i_op = &btrfs_file_inode_operations;
 		break;
@@ -873,7 +880,7 @@ static int btrfs_cow_one_page(struct inode *inode, struct page *page,
 			      size_t zero_start)
 {
 	char *kaddr;
-	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	u64 page_start = (u64)page->index << PAGE_CACHE_SHIFT;
 	u64 page_end = page_start + PAGE_CACHE_SIZE - 1;
@@ -884,12 +891,12 @@ static int btrfs_cow_one_page(struct inode *inode, struct page *page,
 	WARN_ON(!PageLocked(page));
 	set_page_extent_mapped(page);
 
-	lock_extent(em_tree, page_start, page_end, GFP_NOFS);
+	lock_extent(io_tree, page_start, page_end, GFP_NOFS);
 	delalloc_start = page_start;
-	existing_delalloc = count_range_bits(&BTRFS_I(inode)->extent_tree,
+	existing_delalloc = count_range_bits(&BTRFS_I(inode)->io_tree,
 					     &delalloc_start, page_end,
 					     PAGE_CACHE_SIZE, EXTENT_DELALLOC);
-	set_extent_delalloc(&BTRFS_I(inode)->extent_tree, page_start,
+	set_extent_delalloc(&BTRFS_I(inode)->io_tree, page_start,
 			    page_end, GFP_NOFS);
 
 	spin_lock(&root->fs_info->delalloc_lock);
@@ -903,7 +910,7 @@ static int btrfs_cow_one_page(struct inode *inode, struct page *page,
 		kunmap(page);
 	}
 	set_page_dirty(page);
-	unlock_extent(em_tree, page_start, page_end, GFP_NOFS);
+	unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
 
 	return ret;
 }
@@ -961,7 +968,7 @@ static int btrfs_setattr(struct dentry *dentry, struct iattr *attr)
 	    attr->ia_valid & ATTR_SIZE && attr->ia_size > inode->i_size) {
 		struct btrfs_trans_handle *trans;
 		struct btrfs_root *root = BTRFS_I(inode)->root;
-		struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+		struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 
 		u64 mask = root->sectorsize - 1;
 		u64 pos = (inode->i_size + mask) & ~mask;
@@ -986,7 +993,7 @@ static int btrfs_setattr(struct dentry *dentry, struct iattr *attr)
 
 		btrfs_truncate_page(inode->i_mapping, inode->i_size);
 
-		lock_extent(em_tree, pos, block_end, GFP_NOFS);
+		lock_extent(io_tree, pos, block_end, GFP_NOFS);
 		hole_size = block_end - hole_start;
 
 		mutex_lock(&root->fs_info->fs_mutex);
@@ -1001,11 +1008,13 @@ static int btrfs_setattr(struct dentry *dentry, struct iattr *attr)
 						       inode->i_ino,
 						       hole_start, 0, 0,
 						       hole_size);
+			btrfs_drop_extent_cache(inode, hole_start,
+						hole_size - 1);
 			btrfs_check_file(root, inode);
 		}
 		btrfs_end_transaction(trans, root);
 		mutex_unlock(&root->fs_info->fs_mutex);
-		unlock_extent(em_tree, pos, block_end, GFP_NOFS);
+		unlock_extent(io_tree, pos, block_end, GFP_NOFS);
 		if (err)
 			return err;
 	}
@@ -1189,7 +1198,8 @@ static int btrfs_init_locked_inode(struct inode *inode, void *p)
 	struct btrfs_iget_args *args = p;
 	inode->i_ino = args->ino;
 	BTRFS_I(inode)->root = args->root;
-	extent_map_tree_init(&BTRFS_I(inode)->extent_tree,
+	extent_map_tree_init(&BTRFS_I(inode)->extent_tree, GFP_NOFS);
+	extent_io_tree_init(&BTRFS_I(inode)->io_tree,
 			     inode->i_mapping, GFP_NOFS);
 	return 0;
 }
@@ -1485,7 +1495,8 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
 	if (!inode)
 		return ERR_PTR(-ENOMEM);
 
-	extent_map_tree_init(&BTRFS_I(inode)->extent_tree,
+	extent_map_tree_init(&BTRFS_I(inode)->extent_tree, GFP_NOFS);
+	extent_io_tree_init(&BTRFS_I(inode)->io_tree,
 			     inode->i_mapping, GFP_NOFS);
 	BTRFS_I(inode)->root = root;
 
@@ -1672,9 +1683,10 @@ static int btrfs_create(struct inode *dir, struct dentry *dentry,
 		inode->i_mapping->a_ops = &btrfs_aops;
 		inode->i_fop = &btrfs_file_operations;
 		inode->i_op = &btrfs_file_inode_operations;
-		extent_map_tree_init(&BTRFS_I(inode)->extent_tree,
+		extent_map_tree_init(&BTRFS_I(inode)->extent_tree, GFP_NOFS);
+		extent_io_tree_init(&BTRFS_I(inode)->io_tree,
 				     inode->i_mapping, GFP_NOFS);
-		BTRFS_I(inode)->extent_tree.ops = &btrfs_extent_map_ops;
+		BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
 	}
 	dir->i_sb->s_dirt = 1;
 	btrfs_update_inode_block_group(trans, inode);
@@ -1816,7 +1828,7 @@ out_unlock:
 }
 
 struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
-				    size_t page_offset, u64 start, u64 end,
+				    size_t page_offset, u64 start, u64 len,
 				    int create)
 {
 	int ret;
@@ -1826,7 +1838,6 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 	u64 extent_end = 0;
 	u64 objectid = inode->i_ino;
 	u32 found_type;
-	int failed_insert = 0;
 	struct btrfs_path *path;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
 	struct btrfs_file_extent_item *item;
@@ -1834,6 +1845,7 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 	struct btrfs_key found_key;
 	struct extent_map *em = NULL;
 	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	struct btrfs_trans_handle *trans = NULL;
 
 	path = btrfs_alloc_path();
@@ -1841,24 +1853,26 @@ struct extent_map *btrfs_get_extent(struct inode *inode, struct page *page,
 	mutex_lock(&root->fs_info->fs_mutex);
 
 again:
-	em = lookup_extent_mapping(em_tree, start, end);
+	spin_lock(&em_tree->lock);
+	em = lookup_extent_mapping(em_tree, start, len);
+	spin_unlock(&em_tree->lock);
+
 	if (em) {
 		if (em->start > start) {
-			printk("get_extent start %Lu em start %Lu\n",
-			       start, em->start);
+			printk("get_extent lookup [%Lu %Lu] em [%Lu %Lu]\n",
+			       start, len, em->start, em->len);
 			WARN_ON(1);
 		}
 		goto out;
 	}
+	em = alloc_extent_map(GFP_NOFS);
 	if (!em) {
-		em = alloc_extent_map(GFP_NOFS);
-		if (!em) {
-			err = -ENOMEM;
-			goto out;
-		}
-		em->start = EXTENT_MAP_HOLE;
-		em->end = EXTENT_MAP_HOLE;
+		err = -ENOMEM;
+		goto out;
 	}
+
+	em->start = EXTENT_MAP_HOLE;
+	em->len = (u64)-1;
 	em->bdev = inode->i_sb->s_bdev;
 	ret = btrfs_lookup_file_extent(trans, root, path,
 				       objectid, start, trans != NULL);
@@ -1893,28 +1907,25 @@ again:
 		if (start < extent_start || start >= extent_end) {
 			em->start = start;
 			if (start < extent_start) {
-				if (end < extent_start)
+				if (start + len <= extent_start)
 					goto not_found;
-				em->end = extent_end - 1;
+				em->len = extent_end - extent_start;
 			} else {
-				em->end = end;
+				em->len = len;
 			}
 			goto not_found_em;
 		}
 		bytenr = btrfs_file_extent_disk_bytenr(leaf, item);
 		if (bytenr == 0) {
 			em->start = extent_start;
-			em->end = extent_end - 1;
+			em->len = extent_end - extent_start;
 			em->block_start = EXTENT_MAP_HOLE;
-			em->block_end = EXTENT_MAP_HOLE;
 			goto insert;
 		}
 		bytenr += btrfs_file_extent_offset(leaf, item);
 		em->block_start = bytenr;
-		em->block_end = em->block_start +
-			btrfs_file_extent_num_bytes(leaf, item) - 1;
 		em->start = extent_start;
-		em->end = extent_end - 1;
+		em->len = extent_end - extent_start;
 		goto insert;
 	} else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
 		unsigned long ptr;
@@ -1925,25 +1936,24 @@ again:
 
 		size = btrfs_file_extent_inline_len(leaf, btrfs_item_nr(leaf,
 						    path->slots[0]));
-		extent_end = (extent_start + size - 1) |
-			((u64)root->sectorsize - 1);
+		extent_end = (extent_start + size + root->sectorsize - 1) &
+			~((u64)root->sectorsize - 1);
 		if (start < extent_start || start >= extent_end) {
 			em->start = start;
 			if (start < extent_start) {
-				if (end < extent_start)
+				if (start + len <= extent_start)
 					goto not_found;
-				em->end = extent_end;
+				em->len = extent_end - extent_start;
 			} else {
-				em->end = end;
+				em->len = len;
 			}
 			goto not_found_em;
 		}
 		em->block_start = EXTENT_MAP_INLINE;
-		em->block_end = EXTENT_MAP_INLINE;
 
 		if (!page) {
 			em->start = extent_start;
-			em->end = extent_start + size - 1;
+			em->len = size;
 			goto out;
 		}
 
@@ -1952,8 +1962,7 @@ again:
 		copy_size = min_t(u64, PAGE_CACHE_SIZE - page_offset,
 				size - extent_offset);
 		em->start = extent_start + extent_offset;
-		em->end = (em->start + copy_size -1) |
-			((u64)root->sectorsize -1);
+		em->len = copy_size;
 		map = kmap(page);
 		ptr = btrfs_file_extent_inline_start(item) + extent_offset;
 		if (create == 0 && !PageUptodate(page)) {
@@ -1974,7 +1983,8 @@ again:
 			btrfs_mark_buffer_dirty(leaf);
 		}
 		kunmap(page);
-		set_extent_uptodate(em_tree, em->start, em->end, GFP_NOFS);
+		set_extent_uptodate(io_tree, em->start,
+				    extent_map_end(em) - 1, GFP_NOFS);
 		goto insert;
 	} else {
 		printk("unkknown found_type %d\n", found_type);
@@ -1982,33 +1992,29 @@ again:
 	}
 not_found:
 	em->start = start;
-	em->end = end;
+	em->len = len;
 not_found_em:
 	em->block_start = EXTENT_MAP_HOLE;
-	em->block_end = EXTENT_MAP_HOLE;
 insert:
 	btrfs_release_path(root, path);
-	if (em->start > start || em->end < start) {
-		printk("bad extent! em: [%Lu %Lu] passed [%Lu %Lu]\n", em->start, em->end, start, end);
+	if (em->start > start || extent_map_end(em) <= start) {
+		printk("bad extent! em: [%Lu %Lu] passed [%Lu %Lu]\n", em->start, em->len, start, len);
 		err = -EIO;
 		goto out;
 	}
+
+	err = 0;
+	spin_lock(&em_tree->lock);
 	ret = add_extent_mapping(em_tree, em);
 	if (ret == -EEXIST) {
 		free_extent_map(em);
-		em = NULL;
-		if (0 && failed_insert == 1) {
-			btrfs_drop_extent_cache(inode, start, end);
-		}
-		failed_insert++;
-		if (failed_insert > 5) {
-			printk("failing to insert %Lu %Lu\n", start, end);
+		em = lookup_extent_mapping(em_tree, start, len);
+		if (!em) {
 			err = -EIO;
-			goto out;
+			printk("failing to insert %Lu %Lu\n", start, len);
 		}
-		goto again;
 	}
-	err = 0;
+	spin_unlock(&em_tree->lock);
 out:
 	btrfs_free_path(path);
 	if (trans) {
@@ -2032,14 +2038,14 @@ static sector_t btrfs_bmap(struct address_space *mapping, sector_t iblock)
 
 int btrfs_readpage(struct file *file, struct page *page)
 {
-	struct extent_map_tree *tree;
-	tree = &BTRFS_I(page->mapping->host)->extent_tree;
+	struct extent_io_tree *tree;
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
 	return extent_read_full_page(tree, page, btrfs_get_extent);
 }
 
 static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
 {
-	struct extent_map_tree *tree;
+	struct extent_io_tree *tree;
 
 
 	if (current->flags & PF_MEMALLOC) {
@@ -2047,15 +2053,15 @@ static int btrfs_writepage(struct page *page, struct writeback_control *wbc)
 		unlock_page(page);
 		return 0;
 	}
-	tree = &BTRFS_I(page->mapping->host)->extent_tree;
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
 	return extent_write_full_page(tree, page, btrfs_get_extent, wbc);
 }
 
 static int btrfs_writepages(struct address_space *mapping,
 			    struct writeback_control *wbc)
 {
-	struct extent_map_tree *tree;
-	tree = &BTRFS_I(mapping->host)->extent_tree;
+	struct extent_io_tree *tree;
+	tree = &BTRFS_I(mapping->host)->io_tree;
 	return extent_writepages(tree, mapping, btrfs_get_extent, wbc);
 }
 
@@ -2063,19 +2069,21 @@ static int
 btrfs_readpages(struct file *file, struct address_space *mapping,
 		struct list_head *pages, unsigned nr_pages)
 {
-	struct extent_map_tree *tree;
-	tree = &BTRFS_I(mapping->host)->extent_tree;
+	struct extent_io_tree *tree;
+	tree = &BTRFS_I(mapping->host)->io_tree;
 	return extent_readpages(tree, mapping, pages, nr_pages,
 				btrfs_get_extent);
 }
 
 static int btrfs_releasepage(struct page *page, gfp_t unused_gfp_flags)
 {
-	struct extent_map_tree *tree;
+	struct extent_io_tree *tree;
+	struct extent_map_tree *map;
 	int ret;
 
-	tree = &BTRFS_I(page->mapping->host)->extent_tree;
-	ret = try_release_extent_mapping(tree, page);
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
+	map = &BTRFS_I(page->mapping->host)->extent_tree;
+	ret = try_release_extent_mapping(map, tree, page);
 	if (ret == 1) {
 		ClearPagePrivate(page);
 		set_page_private(page, 0);
@@ -2086,9 +2094,9 @@ static int btrfs_releasepage(struct page *page, gfp_t unused_gfp_flags)
 
 static void btrfs_invalidatepage(struct page *page, unsigned long offset)
 {
-	struct extent_map_tree *tree;
+	struct extent_io_tree *tree;
 
-	tree = &BTRFS_I(page->mapping->host)->extent_tree;
+	tree = &BTRFS_I(page->mapping->host)->io_tree;
 	extent_invalidatepage(tree, page, offset);
 	btrfs_releasepage(page, GFP_NOFS);
 }
@@ -2374,7 +2382,7 @@ unsigned long btrfs_force_ra(struct address_space *mapping,
 int btrfs_defrag_file(struct file *file) {
 	struct inode *inode = fdentry(file)->d_inode;
 	struct btrfs_root *root = BTRFS_I(inode)->root;
-	struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
+	struct extent_io_tree *io_tree = &BTRFS_I(inode)->io_tree;
 	struct page *page;
 	unsigned long last_index;
 	unsigned long ra_index = 0;
@@ -2414,13 +2422,13 @@ int btrfs_defrag_file(struct file *file) {
 		page_start = (u64)page->index << PAGE_CACHE_SHIFT;
 		page_end = page_start + PAGE_CACHE_SIZE - 1;
 
-		lock_extent(em_tree, page_start, page_end, GFP_NOFS);
+		lock_extent(io_tree, page_start, page_end, GFP_NOFS);
 		delalloc_start = page_start;
 		existing_delalloc =
-			count_range_bits(&BTRFS_I(inode)->extent_tree,
+			count_range_bits(&BTRFS_I(inode)->io_tree,
 					 &delalloc_start, page_end,
 					 PAGE_CACHE_SIZE, EXTENT_DELALLOC);
-		set_extent_delalloc(em_tree, page_start,
+		set_extent_delalloc(io_tree, page_start,
 				    page_end, GFP_NOFS);
 
 		spin_lock(&root->fs_info->delalloc_lock);
@@ -2428,7 +2436,7 @@ int btrfs_defrag_file(struct file *file) {
 						 existing_delalloc;
 		spin_unlock(&root->fs_info->delalloc_lock);
 
-		unlock_extent(em_tree, page_start, page_end, GFP_NOFS);
+		unlock_extent(io_tree, page_start, page_end, GFP_NOFS);
 		set_page_dirty(page);
 		unlock_page(page);
 		page_cache_release(page);
@@ -2842,9 +2850,10 @@ static int btrfs_symlink(struct inode *dir, struct dentry *dentry,
 		inode->i_mapping->a_ops = &btrfs_aops;
 		inode->i_fop = &btrfs_file_operations;
 		inode->i_op = &btrfs_file_inode_operations;
-		extent_map_tree_init(&BTRFS_I(inode)->extent_tree,
+		extent_map_tree_init(&BTRFS_I(inode)->extent_tree, GFP_NOFS);
+		extent_io_tree_init(&BTRFS_I(inode)->io_tree,
 				     inode->i_mapping, GFP_NOFS);
-		BTRFS_I(inode)->extent_tree.ops = &btrfs_extent_map_ops;
+		BTRFS_I(inode)->io_tree.ops = &btrfs_extent_io_ops;
 	}
 	dir->i_sb->s_dirt = 1;
 	btrfs_update_inode_block_group(trans, inode);
@@ -2934,7 +2943,7 @@ static struct file_operations btrfs_dir_file_operations = {
 #endif
 };
 
-static struct extent_map_ops btrfs_extent_map_ops = {
+static struct extent_io_ops btrfs_extent_io_ops = {
 	.fill_delalloc = run_delalloc_range,
 	.writepage_io_hook = btrfs_writepage_io_hook,
 	.readpage_io_hook = btrfs_readpage_io_hook,
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 8b52c69..f8a1016 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -468,10 +468,15 @@ static int __init init_btrfs_fs(void)
 	err = btrfs_init_cachep();
 	if (err)
 		goto free_transaction_sys;
-	err = extent_map_init();
+
+	err = extent_io_init();
 	if (err)
 		goto free_cachep;
 
+	err = extent_map_init();
+	if (err)
+		goto free_extent_io;
+
 	err = register_filesystem(&btrfs_fs_type);
 	if (err)
 		goto free_extent_map;
@@ -479,6 +484,8 @@ static int __init init_btrfs_fs(void)
 
 free_extent_map:
 	extent_map_exit();
+free_extent_io:
+	extent_io_exit();
 free_cachep:
 	btrfs_destroy_cachep();
 free_transaction_sys:
@@ -492,6 +499,7 @@ static void __exit exit_btrfs_fs(void)
 	btrfs_exit_transaction_sys();
 	btrfs_destroy_cachep();
 	extent_map_exit();
+	extent_io_exit();
 	unregister_filesystem(&btrfs_fs_type);
 	btrfs_exit_sysfs();
 }
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 163c01a..b4a1bc6 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -70,7 +70,7 @@ static int join_transaction(struct btrfs_root *root)
 		INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 		list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
 		btrfs_ordered_inode_tree_init(&cur_trans->ordered_inode_tree);
-		extent_map_tree_init(&cur_trans->dirty_pages,
+		extent_io_tree_init(&cur_trans->dirty_pages,
 				     root->fs_info->btree_inode->i_mapping,
 				     GFP_NOFS);
 	} else {
@@ -153,7 +153,7 @@ int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 	int ret;
 	int err;
 	int werr = 0;
-	struct extent_map_tree *dirty_pages;
+	struct extent_io_tree *dirty_pages;
 	struct page *page;
 	struct inode *btree_inode = root->fs_info->btree_inode;
 	u64 start;
@@ -610,7 +610,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 	struct btrfs_transaction *cur_trans;
 	struct btrfs_transaction *prev_trans = NULL;
 	struct list_head dirty_fs_roots;
-	struct extent_map_tree *pinned_copy;
+	struct extent_io_tree *pinned_copy;
 	DEFINE_WAIT(wait);
 	int ret;
 
@@ -639,7 +639,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 	if (!pinned_copy)
 		return -ENOMEM;
 
-	extent_map_tree_init(pinned_copy,
+	extent_io_tree_init(pinned_copy,
 			     root->fs_info->btree_inode->i_mapping, GFP_NOFS);
 
 	trans->transaction->in_commit = 1;
diff --git a/fs/btrfs/transaction.h b/fs/btrfs/transaction.h
index fd52e9b..c3172dd 100644
--- a/fs/btrfs/transaction.h
+++ b/fs/btrfs/transaction.h
@@ -29,7 +29,7 @@ struct btrfs_transaction {
 	int use_count;
 	int commit_done;
 	struct list_head list;
-	struct extent_map_tree dirty_pages;
+	struct extent_io_tree dirty_pages;
 	unsigned long start_time;
 	struct btrfs_ordered_inode_tree ordered_inode_tree;
 	wait_queue_head_t writer_wait;