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-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 5bc7a0d325e..2c726b7b9fa 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 d3d442f4bbb..ab6d74b6e64 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 941f1b71cd2..81ba6654c33 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;