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author | Marcos Paulo de Souza <mpdesouza@suse.com> | 2021-07-29 05:22:16 -0300 |
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committer | David Sterba <dsterba@suse.com> | 2021-08-23 13:19:09 +0200 |
commit | 0ff40a910f5649dfacc4fb5daa7e73692196342d (patch) | |
tree | d72db74b8b671afb17c773282fa22dc1b0dd0e06 /fs/btrfs/ctree.c | |
parent | ea3dc7d2d1f524eb2a34b6501be38c82be5c7ff1 (diff) | |
download | linux-0ff40a910f5649dfacc4fb5daa7e73692196342d.tar.bz2 |
btrfs: introduce btrfs_search_backwards function
It's a common practice to start a search using offset (u64)-1, which is
the u64 maximum value, meaning that we want the search_slot function to
be set in the last item with the same objectid and type.
Once we are in this position, it's a matter to start a search backwards
by calling btrfs_previous_item, which will check if we'll need to go to
a previous leaf and other necessary checks, only to be sure that we are
in last offset of the same object and type.
The new btrfs_search_backwards function does the all these steps when
necessary, and can be used to avoid code duplication.
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Diffstat (limited to 'fs/btrfs/ctree.c')
-rw-r--r-- | fs/btrfs/ctree.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 99b33a5b33c8..84627cbd5b5b 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -2102,6 +2102,27 @@ again: } /* + * Execute search and call btrfs_previous_item to traverse backwards if the item + * was not found. + * + * Return 0 if found, 1 if not found and < 0 if error. + */ +int btrfs_search_backwards(struct btrfs_root *root, struct btrfs_key *key, + struct btrfs_path *path) +{ + int ret; + + ret = btrfs_search_slot(NULL, root, key, path, 0, 0); + if (ret > 0) + ret = btrfs_previous_item(root, path, key->objectid, key->type); + + if (ret == 0) + btrfs_item_key_to_cpu(path->nodes[0], key, path->slots[0]); + + return ret; +} + +/* * adjust the pointers going up the tree, starting at level * making sure the right key of each node is points to 'key'. * This is used after shifting pointers to the left, so it stops |