Adding a new 'stripe_size' sysfs entry to set and show stripe_size.
After that, 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
stripe_size should not be bigger than PAGE_SIZE, and it requires to be
multiple of 4096.
Signed-off-by: Yufen Yu <yuyufen@xxxxxxxxxx>
---
drivers/md/raid5.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 94 insertions(+)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 84c35eb225b4..338a0732c202 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -6699,6 +6699,99 @@ 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", conf->stripe_size);
+ spin_unlock(&mddev->lock);
+ return ret;
+}
+
+static ssize_t
+raid5_store_stripe_size(struct mddev *mddev, const char *page, size_t len)
+{
+ struct r5conf *conf;
+ unsigned long new;
+ int err;
+ int nr;
+
+ if (len >= PAGE_SIZE)
+ return -EINVAL;
+ if (kstrtoul(page, 10, &new))
+ return -EINVAL;
+ /*
+ * When PAGE_SZIE is 4096, we don't need to modify stripe_size.
+ * And the value should not be bigger than PAGE_SIZE.
+ * It requires to be multiple of 4096.
+ */
+ if (PAGE_SIZE == 4096 || new % 4096 != 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);
+
+ if (mddev->sync_thread ||
+ test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
+ mddev->reshape_position != MaxSector ||
+ mddev->sysfs_active) {
+ err = -EBUSY;
+ goto out_unlock;
+ }
+
+ nr = conf->max_nr_stripes;
+
+ /* 1. suspend raid array */
+ mddev_suspend(mddev);
+
+ /* 2. free all old stripe_head */
+ mutex_lock(&conf->cache_size_mutex);
+ shrink_stripes(conf);
+
+ /* 3. set new stripe_size */
+ conf->stripe_size = new;
+ conf->stripe_shift = ilog2(new) - 9;
+ conf->stripe_sectors = new >> 9;
+
+ /* 4. allocate new stripe_head */
+ if (grow_stripes(conf, nr)) {
+ pr_warn("md/raid:%s: couldn't allocate buffers\n",
+ mdname(mddev));
+ err = -ENOMEM;
+ }
+ mutex_unlock(&conf->cache_size_mutex);
+
+ /* 5. resume raid array */
+ 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);
static ssize_t
raid5_show_preread_threshold(struct mddev *mddev, char *page)
@@ -6887,6 +6980,7 @@ 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,
--
2.25.4
