[PATCH 6.18 031/396] btrfs: raid56: fix an incorrect csum skip during scrub

6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Qu Wenruo <[email protected]>

[ Upstream commit 330dcc553f282e8dc0b88c9495b4c296465364e1 ]

Commit 7425a2894019 ("btrfs: introduce btrfs_bio_for_each_block_all()
helper") uses the new helper to replace the nested loop inside
verify_bio_data_sectors(), which simplifies the code.

However that also changed the behavior of "continue" when a block has no
data checksum.

Previously the "continue" would skip the old for() loop, which would also
increase @total_sector_nr.

Now the "continue" will skip the new btrfs_bio_for_each_block_all()
loop, which doesn't update @total_sector_nr.

This means if we hit a block that has no data checksum, we will skip all
the remaining blocks no matter if they have data checksum.
As @total_sector_nr will never be updated, and that test_bit() will
always return false.

Fix it by increasing @total_sector_nr before calling "continue".

Fixes: 7425a2894019 ("btrfs: introduce btrfs_bio_for_each_block_all() helper")
Reviewed-by: Daniel Vacek <[email protected]>
Signed-off-by: Qu Wenruo <[email protected]>
Reviewed-by: David Sterba <[email protected]>
Signed-off-by: David Sterba <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
---
 fs/btrfs/raid56.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 0135dceb7baaa..4d4852f2ba7eb 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -1583,8 +1583,10 @@ static void verify_bio_data_sectors(struct btrfs_raid_bio *rbio,
 		int ret;
 
 		/* No csum for this sector, skip to the next sector. */
-		if (!test_bit(total_sector_nr, rbio->csum_bitmap))
+		if (!test_bit(total_sector_nr, rbio->csum_bitmap)) {
+			total_sector_nr++;
 			continue;
+		}
 
 		ret = btrfs_check_block_csum(fs_info, paddr,
 					     csum_buf, expected_csum);
-- 
2.53.0