btrfs: don't warn if discard range is not aligned to sector

commit a208b3f132b48e1f94f620024e66fea635925877 upstream.

There's a warning in btrfs_issue_discard() when the range is not aligned
to 512 bytes, originally added in 4d89d377bbb0 ("btrfs:
btrfs_issue_discard ensure offset/length are aligned to sector
boundaries"). We can't do sub-sector writes anyway so the adjustment is
the only thing that we can do and the warning is unnecessary.

CC: stable@vger.kernel.org # 4.19+
Reported-by: syzbot+4a4f1eba14eb5c3417d1@syzkaller.appspotmail.com
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 91fe57e..d421e28 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -1245,7 +1245,8 @@ static int btrfs_issue_discard(struct block_device *bdev, u64 start, u64 len,
        u64 bytes_left, end;
        u64 aligned_start = ALIGN(start, 1 << SECTOR_SHIFT);
 
-       if (WARN_ON(start != aligned_start)) {
+       /* Adjust the range to be aligned to 512B sectors if necessary. */
+       if (start != aligned_start) {
                len -= aligned_start - start;
                len = round_down(len, 1 << SECTOR_SHIFT);
                start = aligned_start;