Commit 74be9510 authored Jul 05, 2013 by Filipe David Borba Manana Committed by Chris Mason Sep 01, 2013

Btrfs: optimize btrfs_lookup_extent_info()



If we're looking for a metadata item in the tree and the
search fails with return value of 1, and the slot doesn't
point to the first item in the leaf, check if the previous
item in the leaf corresponds to an extent item for the same
object id - if it does, then don't do another tree search
to get it.

This optimization is already done by btrfs-progs.

V2: updated commit message.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

parent d7901554

fs/btrfs/extent-tree.c

+17 −4

Original line number	Diff line number	Diff line
		@@ -771,11 +771,24 @@ again:
		goto out_free;

		if (ret > 0 && metadata && key.type == BTRFS_METADATA_ITEM_KEY) {
		metadata = 0;
		if (path->slots[0]) {
		path->slots[0]--;
		btrfs_item_key_to_cpu(path->nodes[0], &key,
		path->slots[0]);
		if (key.objectid == bytenr &&
		key.type == BTRFS_EXTENT_ITEM_KEY &&
		key.offset == root->leafsize)
		ret = 0;
		}
		if (ret) {
		key.objectid = bytenr;
		key.type = BTRFS_EXTENT_ITEM_KEY;
		key.offset = root->leafsize;
		btrfs_release_path(path);
		goto again;
		}
		}

		if (ret == 0) {
		leaf = path->nodes[0];

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