Re: [PATCH] raid1: fix nr_pending leak in REQ_ATOMIC bad-block error path

[John Garry]

On 30/05/2026 16:14, Abd-Alrhman Masalkhi wrote:
> In raid1_write_request(), each per-mirror loop iteration begins by
> incrementing rdev->nr_pending. If a REQ_ATOMIC write encounters a
> badblock within the requested range, the code jumps to err_handle
> without dropping the reference taken for the current mirror.
>
> err_handle's cleanup loop will only decrements for k < i and
> r1_bio->bios[k] is non-NULL. The current slot is therefore skipped,
> leaving its nr_pending reference leaked permanently. The reference
> prevents the rdev from ever being removed, since raid1_remove_conf()
> refuses to remove an rdev with nr_pending > 0.
>
> Fix this by calling rdev_dec_pending() before jumping to err_handle.
>
> Fixes: f2a38abf5f1c ("md/raid1: Atomic write support")
> Signed-off-by: Abd-Alrhman Masalkhi <abd.masalkhi@xxxxxxxxx>

FWIW,

Reviewed-by: John Garry <john.g.garry@xxxxxxxxxx>

> ---
>   drivers/md/raid1.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 181400e147c0..0084bbc24076 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -1580,8 +1580,10 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
>   				 * complexity of supporting that is not worth
>   				 * the benefit.
>   				 */
> -				if (bio->bi_opf & REQ_ATOMIC)
> +				if (bio->bi_opf & REQ_ATOMIC) {
> +					rdev_dec_pending(rdev, mddev);

It's not so nice that we have 2x locations that does the 
rdev_dec_pending work

>   					goto err_handle;
> +				}
>   
>   				good_sectors = first_bad - r1_bio->sector;
>   				if (good_sectors < max_sectors)