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authorChris Mason <chris.mason@oracle.com>2009-09-18 16:07:03 -0400
committerChris Mason <chris.mason@oracle.com>2009-09-18 16:08:52 -0400
commitb917b7c3be50435fa8257591b964934e917f2d45 (patch)
treeefdc2f768da474a4904dc6c065cc6e4b9a2379d3
parentf85d7d6c8f2ad4a86a1f4f4e3791f36dede2fa76 (diff)
downloadop-kernel-dev-b917b7c3be50435fa8257591b964934e917f2d45.zip
op-kernel-dev-b917b7c3be50435fa8257591b964934e917f2d45.tar.gz
Btrfs: search for an allocation hint while filling file COW
The allocator has some nice knobs for sending hints about where to try and allocate new blocks, but when we're doing file allocations we're not sending any hint at all. This commit adds a simple extent map search to see if we can quickly and easily find a hint for the allocator. Signed-off-by: Chris Mason <chris.mason@oracle.com>
-rw-r--r--fs/btrfs/extent_map.c48
-rw-r--r--fs/btrfs/extent_map.h2
-rw-r--r--fs/btrfs/inode.c10
3 files changed, 59 insertions, 1 deletions
diff --git a/fs/btrfs/extent_map.c b/fs/btrfs/extent_map.c
index 5bc7a0d..2c726b7 100644
--- a/fs/btrfs/extent_map.c
+++ b/fs/btrfs/extent_map.c
@@ -367,6 +367,54 @@ out:
}
/**
+ * search_extent_mapping - find a nearby extent map
+ * @tree: tree to lookup in
+ * @start: byte offset to start the search
+ * @len: length of the lookup range
+ *
+ * Find and return the first extent_map struct in @tree that intersects the
+ * [start, len] range.
+ *
+ * If one can't be found, any nearby extent may be returned
+ */
+struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
+ u64 start, u64 len)
+{
+ struct extent_map *em;
+ struct rb_node *rb_node;
+ struct rb_node *prev = NULL;
+ struct rb_node *next = NULL;
+
+ rb_node = __tree_search(&tree->map, start, &prev, &next);
+ if (!rb_node && prev) {
+ em = rb_entry(prev, struct extent_map, rb_node);
+ goto found;
+ }
+ if (!rb_node && next) {
+ em = rb_entry(next, struct extent_map, rb_node);
+ goto found;
+ }
+ if (!rb_node) {
+ em = NULL;
+ goto out;
+ }
+ if (IS_ERR(rb_node)) {
+ em = ERR_PTR(PTR_ERR(rb_node));
+ goto out;
+ }
+ em = rb_entry(rb_node, struct extent_map, rb_node);
+ goto found;
+
+ em = NULL;
+ goto out;
+
+found:
+ atomic_inc(&em->refs);
+out:
+ return em;
+}
+
+/**
* remove_extent_mapping - removes an extent_map from the extent tree
* @tree: extent tree to remove from
* @em: extent map beeing removed
diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index d3d442f..ab6d74b 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -60,4 +60,6 @@ void free_extent_map(struct extent_map *em);
int __init extent_map_init(void);
void extent_map_exit(void);
int unpin_extent_cache(struct extent_map_tree *tree, u64 start, u64 len);
+struct extent_map *search_extent_mapping(struct extent_map_tree *tree,
+ u64 start, u64 len);
#endif
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 941f1b7..81ba665 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -726,6 +726,15 @@ static noinline int cow_file_range(struct inode *inode,
BUG_ON(disk_num_bytes >
btrfs_super_total_bytes(&root->fs_info->super_copy));
+
+ read_lock(&BTRFS_I(inode)->extent_tree.lock);
+ em = search_extent_mapping(&BTRFS_I(inode)->extent_tree,
+ start, num_bytes);
+ if (em) {
+ alloc_hint = em->block_start;
+ free_extent_map(em);
+ }
+ read_unlock(&BTRFS_I(inode)->extent_tree.lock);
btrfs_drop_extent_cache(inode, start, start + num_bytes - 1, 0);
while (disk_num_bytes > 0) {
@@ -738,7 +747,6 @@ static noinline int cow_file_range(struct inode *inode,
em = alloc_extent_map(GFP_NOFS);
em->start = start;
em->orig_start = em->start;
-
ram_size = ins.offset;
em->len = ins.offset;
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