On Fri, Nov 1, 2019 at 7:23 AM <jgq516@xxxxxxxxx> wrote:
>
> From: Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx>
>
> With the new sysfs node, we can use it to control if raid1 array
> wants serialization for write request or not.
>
> Signed-off-by: Guoqing Jiang <guoqing.jiang@xxxxxxxxxxxxxxx>
> ---
> drivers/md/md.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
> drivers/md/md.h | 1 +
> 2 files changed, 47 insertions(+)
>
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 43b7da334e4a..8df94a58512b 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -174,6 +174,7 @@ void mddev_create_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
> memalloc_noio_restore(noio_flag);
> if (!mddev->serial_info_pool)
> pr_err("can't alloc memory pool for writemostly\n");
> + mddev->serialize_policy = true;
> if (!is_suspend)
> mddev_resume(mddev);
> }
> @@ -216,6 +217,7 @@ static void mddev_destroy_serial_pool(struct mddev *mddev, struct md_rdev *rdev,
> mempool_destroy(mddev->serial_info_pool);
> mddev->serial_info_pool = NULL;
> }
> + mddev->serialize_policy = false;
> mddev_resume(mddev);
> }
> }
> @@ -5261,6 +5263,49 @@ static struct md_sysfs_entry md_fail_last_dev =
> __ATTR(fail_last_dev, S_IRUGO | S_IWUSR, fail_last_dev_show,
> fail_last_dev_store);
>
> +static ssize_t serialize_policy_show(struct mddev *mddev, char *page)
> +{
> + return sprintf(page, "%d\n", mddev->serialize_policy);
Maybe show something like "n/a" for non-raid1?
> +}
> +
> +/*
> + * Setting serialize_policy to true to enforce write IO is not reordered
> + * for raid1.
> + */
> +static ssize_t
> +serialize_policy_store(struct mddev *mddev, const char *buf, size_t len)
> +{
> + int err;
> + bool value;
> +
> + err = kstrtobool(buf, &value);
> + if (err || value == mddev->serialize_policy)
> + return err ?: -EINVAL;
I think we should not return -EINVAL for value == serialize_policy case.
> +
> + err = mddev_lock(mddev);
> + if (err)
> + return err;
> + if (mddev->pers == NULL ||
> + (strncmp(mddev->pers->name, "raid1", 4) != 0)) {
Check pers->level == 1 instead?
Also, we need to recheck serialize_policy here.
> + pr_err("md: serialize_policy is only effective for raid1\n");
> + err = -EINVAL;
> + goto unlock;
> + }
> +
> + if (value)
> + mddev_create_serial_pool(mddev, NULL, false, true);
> + else
> + mddev_destroy_serial_pool(mddev, NULL, true);
> +unlock:
> + mddev_unlock(mddev);
> + return err ?: len;
> +}
> +
> +static struct md_sysfs_entry md_serialize_policy =
> +__ATTR(serialize_policy, S_IRUGO | S_IWUSR, serialize_policy_show,
> + serialize_policy_store);
> +
> +
> static struct attribute *md_default_attrs[] = {
> &md_level.attr,
> &md_layout.attr,
> @@ -5278,6 +5323,7 @@ static struct attribute *md_default_attrs[] = {
> &max_corr_read_errors.attr,
> &md_consistency_policy.attr,
> &md_fail_last_dev.attr,
> + &md_serialize_policy.attr,
> NULL,
> };
>
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index 291a59a94528..161772066dab 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -494,6 +494,7 @@ struct mddev {
>
> bool has_superblocks:1;
> bool fail_last_dev:1;
> + bool serialize_policy:1;
> };
>
> enum recovery_flags {
> --
> 2.17.1
>
