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btrfs: tag as unlikely the key comparison when checking sibling keys 

When checking siblings keys, before moving keys from one node/leaf to a
sibling node/leaf, it's very unexpected to have the last key of the left
sibling greater than or equals to the first key of the right sibling, as
that means we have a (serious) corruption that breaks the key ordering
properties of a b+tree. Since this is unexpected, surround the comparison
with the unlikely macro, which helps the compiler generate better code
for the most expected case (no existing b+tree corruption). This is also
what we do for other unexpected cases of invalid key ordering (like at
btrfs_set_item_key_safe()).

Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Filipe Manana 2023-04-26 11:51:37 +01:00 committed by David Sterba
parent f2db4d5cb4
commit 88ad95b055
1 changed files with 1 additions and 1 deletions
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fs/btrfs/ctree.c
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@ -2707,7 +2707,7 @@ static bool check_sibling_keys(struct extent_buffer *left,
btrfs_item_key_to_cpu(right, &right_first, 0);
}
if (btrfs_comp_cpu_keys(&left_last, &right_first) >= 0) {
if (unlikely(btrfs_comp_cpu_keys(&left_last, &right_first) >= 0)) {
btrfs_crit(left->fs_info, "left extent buffer:");
btrfs_print_tree(left, false);
btrfs_crit(left->fs_info, "right extent buffer:");