From: Guoqing Jiang guoqing.jiang@linux.dev
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@vger.kernel.org # v5.12+ Cc: Jens Stutte jens@chianterastutte.eu Reported-by: Jens Stutte jens@chianterastutte.eu Signed-off-by: Guoqing Jiang guoqing.jiang@linux.dev Signed-off-by: Song Liu songliubraving@fb.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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