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>
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 0770c91..3e2a804 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1933,6 +1933,7 @@
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 @@
}
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++;