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>

1 files changed, 84 insertions, 3035 deletions

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);