Re: [PATCH 3/3] md/raid10: use get_rdev_repl_from_mirror() to get devices

[Yu Kuai]

在 2023/06/28 9:57, linan666@xxxxxxxxxxxxxxx 写道:
> From: Li Nan <linan122@xxxxxxxxxx>
>
> Commit 2ae6aaf76912 ("md/raid10: fix io loss while replacement replace
> rdev") reads replacement first to prevent io loss. However, there are same
> issue in wait_blocked_dev() and raid10_handle_discard(), too. Fix it by
> using get_rdev_repl_from_mirror() to get devices.

LGTM

Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> Fixes: d30588b2731f ("md/raid10: improve raid10 discard request")
> Fixes: f2e7e269a752 ("md/raid10: pull the code that wait for blocked dev into one function")
> Signed-off-by: Li Nan <linan122@xxxxxxxxxx>
> ---
>   drivers/md/raid10.c | 15 +++++----------
>   1 file changed, 5 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index eaaf6307ddda..2d55374d8b22 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -1376,11 +1376,9 @@ static void wait_blocked_dev(struct mddev *mddev, struct r10bio *r10_bio)
>   	blocked_rdev = NULL;
>   	rcu_read_lock();
>   	for (i = 0; i < conf->copies; i++) {
> -		struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
> -		struct md_rdev *rrdev = rcu_dereference(
> -			conf->mirrors[i].replacement);
> -		if (rdev == rrdev)
> -			rrdev = NULL;
> +		struct md_rdev *rdev, *rrdev;
> +
> +		get_rdev_repl_from_mirror(&conf->mirrors[i], &rdev, &rrdev);
>   		if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
>   			atomic_inc(&rdev->nr_pending);
>   			blocked_rdev = rdev;
> @@ -1816,15 +1814,12 @@ static int raid10_handle_discard(struct mddev *mddev, struct bio *bio)
>   	 */
>   	rcu_read_lock();
>   	for (disk = 0; disk < geo->raid_disks; disk++) {
> -		struct md_rdev *rdev = rcu_dereference(conf->mirrors[disk].rdev);
> -		struct md_rdev *rrdev = rcu_dereference(
> -			conf->mirrors[disk].replacement);
> +		struct md_rdev *rdev, *rrdev;
>   
> +		get_rdev_repl_from_mirror(&conf->mirrors[disk], &rdev, &rrdev);
>   		r10_bio->devs[disk].bio = NULL;
>   		r10_bio->devs[disk].repl_bio = NULL;
>   
> -		if (rdev == rrdev)
> -			rrdev = NULL;
>   		if (rdev && (test_bit(Faulty, &rdev->flags)))
>   			rdev = NULL;
>   		if (rrdev && (test_bit(Faulty, &rrdev->flags)))