On Thu, Feb 22, 2024 at 4:05 PM Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
>
> From: Yu Kuai <yukuai3@xxxxxxxxxx>
>
> If resync is in progress, read_balance() should find the first usable
> disk, otherwise, data could be inconsistent after resync is done. raid1
> and raid10 implement the same checking, hence factor out the checking
> to make code cleaner.
>
> Noted that raid1 is using 'mddev->recovery_cp', which is updated after
> all resync IO is done, while raid10 is using 'conf->next_resync', which
> is inaccurate because raid10 update it before submitting resync IO.
> Fortunately, raid10 read IO can't concurrent with resync IO, hence there
> is no problem. And this patch also switch raid10 to use
> 'mddev->recovery_cp'.
>
> Co-developed-by: Paul Luse <paul.e.luse@xxxxxxxxxxxxxxx>
> Signed-off-by: Paul Luse <paul.e.luse@xxxxxxxxxxxxxxx>
> Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> ---
> drivers/md/raid1-10.c | 20 ++++++++++++++++++++
> drivers/md/raid1.c | 15 ++-------------
> drivers/md/raid10.c | 13 ++-----------
> 3 files changed, 24 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/md/raid1-10.c b/drivers/md/raid1-10.c
> index 9bc0f0022a6c..2ea1710a3b70 100644
> --- a/drivers/md/raid1-10.c
> +++ b/drivers/md/raid1-10.c
> @@ -276,3 +276,23 @@ static inline int raid1_check_read_range(struct md_rdev *rdev,
> *len = first_bad + bad_sectors - this_sector;
> return 0;
> }
> +
> +/*
> + * Check if read should choose the first rdev.
> + *
> + * Balance on the whole device if no resync is going on (recovery is ok) or
> + * below the resync window. Otherwise, take the first readable disk.
> + */
> +static inline bool raid1_should_read_first(struct mddev *mddev,
> + sector_t this_sector, int len)
> +{
> + if ((mddev->recovery_cp < this_sector + len))
> + return true;
> +
> + if (mddev_is_clustered(mddev) &&
> + md_cluster_ops->area_resyncing(mddev, READ, this_sector,
> + this_sector + len))
> + return true;
> +
> + return false;
> +}
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index d0bc67e6d068..8089c569e84f 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -605,11 +605,6 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect
> struct md_rdev *rdev;
> int choose_first;
>
> - /*
> - * Check if we can balance. We can balance on the whole
> - * device if no resync is going on, or below the resync window.
> - * We take the first readable disk when above the resync window.
> - */
> retry:
> sectors = r1_bio->sectors;
> best_disk = -1;
> @@ -618,16 +613,10 @@ static int read_balance(struct r1conf *conf, struct r1bio *r1_bio, int *max_sect
> best_pending_disk = -1;
> min_pending = UINT_MAX;
> best_good_sectors = 0;
> + choose_first = raid1_should_read_first(conf->mddev, this_sector,
> + sectors);
> clear_bit(R1BIO_FailFast, &r1_bio->state);
>
> - if ((conf->mddev->recovery_cp < this_sector + sectors) ||
> - (mddev_is_clustered(conf->mddev) &&
> - md_cluster_ops->area_resyncing(conf->mddev, READ, this_sector,
> - this_sector + sectors)))
> - choose_first = 1;
> - else
> - choose_first = 0;
> -
> for (disk = 0 ; disk < conf->raid_disks * 2 ; disk++) {
> sector_t dist;
> sector_t first_bad;
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index 1f6693e40e12..22bcc3ce11d3 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -747,17 +747,8 @@ static struct md_rdev *read_balance(struct r10conf *conf,
> best_good_sectors = 0;
> do_balance = 1;
> clear_bit(R10BIO_FailFast, &r10_bio->state);
> - /*
> - * Check if we can balance. We can balance on the whole
> - * device if no resync is going on (recovery is ok), or below
> - * the resync window. We take the first readable disk when
> - * above the resync window.
> - */
> - if ((conf->mddev->recovery_cp < MaxSector
> - && (this_sector + sectors >= conf->next_resync)) ||
> - (mddev_is_clustered(conf->mddev) &&
> - md_cluster_ops->area_resyncing(conf->mddev, READ, this_sector,
> - this_sector + sectors)))
> +
> + if (raid1_should_read_first(conf->mddev, this_sector, sectors))
> do_balance = 0;
>
> for (slot = 0; slot < conf->copies ; slot++) {
> --
> 2.39.2
>
>
This patch looks good to me.
Reviewed-by: Xiao Ni <xni@xxxxxxxxxx>
