[PATCH] md: suspend array while updating raid1 raid_disks via sysfs

[dannyshih <dannyshih@synology.com>]

From: FengWei Shih <dannyshih@synology.com>

When an I/O error occurs, the corresponding r1bio might be queued during
raid1_reshape() and not released. Leads to r1bio release with wrong
raid_disks.

* raid1_reshape() calls freeze_array(), which only waits for r1bios be
  queued or released.

Since only normal I/O might be queued while an I/O error occurs, suspending
the array avoids this issue.

Signed-off-by: FengWei Shih <dannyshih@synology.com>
---
 drivers/md/md.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index e5922a682953..6424652bce6e 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4402,12 +4402,13 @@ raid_disks_store(struct mddev *mddev, const char *buf, size_t len)
 {
 	unsigned int n;
 	int err;
+	bool need_suspend = (mddev->pers && mddev->level == 1);
 
 	err = kstrtouint(buf, 10, &n);
 	if (err < 0)
 		return err;
 
-	err = mddev_lock(mddev);
+	err = need_suspend ? mddev_suspend_and_lock(mddev) : mddev_lock(mddev);
 	if (err)
 		return err;
 	if (mddev->pers)
@@ -4432,7 +4433,7 @@ raid_disks_store(struct mddev *mddev, const char *buf, size_t len)
 	} else
 		mddev->raid_disks = n;
 out_unlock:
-	mddev_unlock(mddev);
+	need_suspend ? mddev_unlock_and_resume(mddev) : mddev_unlock(mddev);
 	return err ? err : len;
 }
 static struct md_sysfs_entry md_raid_disks =
-- 
2.17.1


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