Btrfs: Simplify the logic in alloc_extent_buffer() for existing extent buffer case

alloc_extent_buffer() uses radix_tree_lookup() when radix_tree_insert()
fails with EEXIST. That part of the code is very similar to the code in
find_extent_buffer(). This patch replaces radix_tree_lookup() and
surrounding code in alloc_extent_buffer() with find_extent_buffer().

Note that radix_tree_lookup() does not need to be protected by
tree->buffer_lock. It is protected by eb->refs.

While at it, this patch
  - changes the other usage of radix_tree_lookup() in alloc_extent_buffer()
    with find_extent_buffer() to reduce redundancy.
  - removes the unused argument 'len' to find_extent_buffer().

Signed-Off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Reviewed-by: Zach Brown <zab@redhat.com>

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 1 insertions, 2 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index b0ea9f4..ebc784a 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1104,8 +1104,7 @@ struct extent_buffer *btrfs_find_tree_block(struct btrfs_root *root,
 {
 	struct inode *btree_inode = root->fs_info->btree_inode;
 	struct extent_buffer *eb;
-	eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree,
-				bytenr, blocksize);
+	eb = find_extent_buffer(&BTRFS_I(btree_inode)->io_tree, bytenr);
 	return eb;
 }