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Commit dd81d459 authored by Naohiro Aota's avatar Naohiro Aota Committed by Chris Mason
Browse files

btrfs: fix search key advancing condition 



The search key advancing condition used in copy_to_sk() is loose. It can
advance the key even if it reaches sk->max_*: e.g. when the max key = (512,
1024, -1) and the current key = (512, 1025, 10), it increments the
offset by 1, continues hopeless search from (512, 1025, 11). This issue
make ioctl() to take unexpectedly long time scanning all the leaf a blocks
one by one.

This commit fix the problem using standard way of key comparison:
btrfs_comp_cpu_keys()

Signed-off-by: default avatarNaohiro Aota <naota@elisp.net>
Reviewed-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarChris Mason <clm@fb.com>
parent d6589101

fs/btrfs/ioctl.c

+9 −3
Original line number Diff line number Diff line
@@ -1933,6 +1933,7 @@ static noinline int copy_to_sk(struct btrfs_root *root, 
	u64 found_transid;

	struct extent_buffer *leaf;

	struct btrfs_ioctl_search_header sh;

	struct btrfs_key test;

	unsigned long item_off;

	unsigned long item_len;

	int nritems;
@@ -2016,12 +2017,17 @@ static noinline int copy_to_sk(struct btrfs_root *root, 
	}

advance_key:

	ret = 0;

	if (key->offset < (u64)-1 && key->offset < sk->max_offset)

	test.objectid = sk->max_objectid;

	test.type = sk->max_type;

	test.offset = sk->max_offset;

	if (btrfs_comp_cpu_keys(key, &test) >= 0)

		ret = 1;

	else if (key->offset < (u64)-1)

		key->offset++;

	else if (key->type < (u8)-1 && key->type < sk->max_type) {

	else if (key->type < (u8)-1) {

		key->offset = 0;

		key->type++;

	} else if (key->objectid < (u64)-1 && key->objectid < sk->max_objectid) {

	} else if (key->objectid < (u64)-1) {

		key->offset = 0;

		key->type = 0;

		key->objectid++;