From: Guoqing Jiang <guoqing.jiang@xxxxxxxxx>
commit fd3b6975e9c11c4fa00965f82a0bfbb3b7b44101 upstream.
Commit 6607cd319b6b91bff94e90f798a61c031650b514 ("raid1: ensure write
behind bio has less than BIO_MAX_VECS sectors") tried to guarantee the
size of behind bio is not bigger than BIO_MAX_VECS sectors.
Unfortunately the same calltrace still could happen since an array could
enable write-behind without write mostly device.
To match the manpage of mdadm (which says "write-behind is only attempted
on drives marked as write-mostly"), we need to check WriteMostly flag to
avoid such unexpected behavior.
[1]. https://bugzilla.kernel.org/show_bug.cgi?id=213181#c25
Cc: stable@xxxxxxxxxxxxxxx # v5.12+
Cc: Jens Stutte <jens@xxxxxxxxxxxxxxxxxx>
Reported-by: Jens Stutte <jens@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Guoqing Jiang <guoqing.jiang@xxxxxxxxx>
Signed-off-by: Song Liu <songliubraving@xxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/raid1.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1496,7 +1496,7 @@ static void raid1_write_request(struct m
if (!r1_bio->bios[i])
continue;
- if (first_clone) {
+ if (first_clone && test_bit(WriteMostly, &rdev->flags)) {
/* do behind I/O ?
* Not if there are too many, or cannot
* allocate memory, or a reader on WriteMostly
