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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: Naohiro Aota <naota@elisp.net>
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
This commit is contained in:
Naohiro Aota 2015-06-30 11:25:43 +09:00 committed by Chris Mason
parent d6589101b6
commit dd81d459a3
1 changed files with 9 additions and 3 deletions
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12
fs/btrfs/ioctl.c
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@ -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++;