Commit 3b5408b9 authored by Yufen Yu's avatar Yufen Yu Committed by Song Liu
Browse files

md/raid5: support config stripe_size by sysfs entry 



Adding a new 'stripe_size' sysfs entry to set and show stripe_size.
stripe_size should not be bigger than PAGE_SIZE, and it requires to
be multiple of 4096. We can adjust stripe_size by writing value into
sysfs entry, likely, set stripe_size as 16KB:

          echo 16384 > /sys/block/md1/md/stripe_size

Show current stripe_size value:

          cat /sys/block/md1/md/stripe_size

For PAGE_SIZE is equal to 4096, 'stripe_size' can just be read.

Signed-off-by: default avatarYufen Yu <yuyufen@huawei.com>
Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
parent e2368582

drivers/md/raid5.c

+72 −0
Original line number Diff line number Diff line
@@ -6503,6 +6503,77 @@ raid5_rmw_level = __ATTR(rmw_level, S_IRUGO | S_IWUSR, 
			 raid5_show_rmw_level,

			 raid5_store_rmw_level);



static ssize_t

raid5_show_stripe_size(struct mddev  *mddev, char *page)

{

	struct r5conf *conf;

	int ret = 0;



	spin_lock(&mddev->lock);

	conf = mddev->private;

	if (conf)

		ret = sprintf(page, "%lu\n", RAID5_STRIPE_SIZE(conf));

	spin_unlock(&mddev->lock);

	return ret;

}



#if PAGE_SIZE != DEFAULT_STRIPE_SIZE

static ssize_t

raid5_store_stripe_size(struct mddev  *mddev, const char *page, size_t len)

{

	struct r5conf *conf;

	unsigned long new;

	int err;



	if (len >= PAGE_SIZE)

		return -EINVAL;

	if (kstrtoul(page, 10, &new))

		return -EINVAL;



	/*

	 * The value should not be bigger than PAGE_SIZE. It requires to

	 * be multiple of DEFAULT_STRIPE_SIZE.

	 */

	if (new % DEFAULT_STRIPE_SIZE != 0 || new > PAGE_SIZE || new == 0)

		return -EINVAL;



	err = mddev_lock(mddev);

	if (err)

		return err;



	conf = mddev->private;

	if (!conf) {

		err = -ENODEV;

		goto out_unlock;

	}



	if (new == conf->stripe_size)

		goto out_unlock;



	pr_debug("md/raid: change stripe_size from %lu to %lu\n",

			conf->stripe_size, new);



	mddev_suspend(mddev);

	conf->stripe_size = new;

	conf->stripe_shift = ilog2(new) - 9;

	conf->stripe_sectors = new >> 9;

	mddev_resume(mddev);



out_unlock:

	mddev_unlock(mddev);

	return err ?: len;

}



static struct md_sysfs_entry

raid5_stripe_size = __ATTR(stripe_size, 0644,

			 raid5_show_stripe_size,

			 raid5_store_stripe_size);

#else

static struct md_sysfs_entry

raid5_stripe_size = __ATTR(stripe_size, 0444,

			 raid5_show_stripe_size,

			 NULL);

#endif



static ssize_t

raid5_show_preread_threshold(struct mddev *mddev, char *page)
@@ -6691,6 +6762,7 @@ static struct attribute *raid5_attrs[] = { 
	&raid5_group_thread_cnt.attr,

	&raid5_skip_copy.attr,

	&raid5_rmw_level.attr,

	&raid5_stripe_size.attr,

	&r5c_journal_mode.attr,

	&ppl_write_hint.attr,

	NULL,

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