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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>
This commit is contained in:
Filipe David Borba Manana 2013-07-05 23:12:06 +01:00 committed by Chris Mason
parent d790155457
commit 74be951087
1 changed files with 17 additions and 4 deletions
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13
fs/btrfs/extent-tree.c
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@ -771,11 +771,24 @@ int btrfs_lookup_extent_info(struct btrfs_trans_handle *trans,
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];