1 files changed, 49 insertions, 12 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 970a8c42ba9..38697283aaf 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -214,16 +214,33 @@ static inline mddev_t *mddev_get(mddev_t *mddev)
         return mddev;
 }
 
+static void mddev_delayed_delete(struct work_struct *ws)
+{
+        mddev_t *mddev = container_of(ws, mddev_t, del_work);
+        kobject_del(&mddev->kobj);
+        kobject_put(&mddev->kobj);
+}
+
 static void mddev_put(mddev_t *mddev)
 {
         if (!atomic_dec_and_lock(&mddev->active, &all_mddevs_lock))
                 return;
-        if (!mddev->raid_disks && list_empty(&mddev->disks)) {
+        if (!mddev->raid_disks && list_empty(&mddev->disks) &&
+            !mddev->hold_active) {
                 list_del(&mddev->all_mddevs);
-                spin_unlock(&all_mddevs_lock);
-                kobject_put(&mddev->kobj);
-        } else
-                spin_unlock(&all_mddevs_lock);
+                if (mddev->gendisk) {
+                        /* we did a probe so need to clean up.
+                         * Call schedule_work inside the spinlock
+                         * so that flush_scheduled_work() after
+                         * mddev_find will succeed in waiting for the
+                         * work to be done.
+                         */
+                        INIT_WORK(&mddev->del_work, mddev_delayed_delete);
+                        schedule_work(&mddev->del_work);
+                } else
+                        kfree(mddev);
+        }
+        spin_unlock(&all_mddevs_lock);
 }
 
 static mddev_t * mddev_find(dev_t unit)
@@ -242,6 +259,7 @@ static mddev_t * mddev_find(dev_t unit)
 
         if (new) {
                 list_add(&new->all_mddevs, &all_mddevs);
+                mddev->hold_active = UNTIL_IOCTL;
                 spin_unlock(&all_mddevs_lock);
                 return new;
         }
@@ -3435,6 +3453,8 @@ md_attr_store(struct kobject *kobj, struct attribute *attr,
         if (!capable(CAP_SYS_ADMIN))
                 return -EACCES;
         rv = mddev_lock(mddev);
+        if (mddev->hold_active == UNTIL_IOCTL)
+                mddev->hold_active = 0;
         if (!rv) {
                 rv = entry->store(mddev, page, length);
                 mddev_unlock(mddev);
@@ -3484,6 +3504,11 @@ static struct kobject *md_probe(dev_t dev, int *part, void *data)
         if (!mddev)
                 return NULL;
 
+        /* wait for any previous instance if this device
+         * to be completed removed (mddev_delayed_delete).
+         */
+        flush_scheduled_work();
+
         mutex_lock(&disks_mutex);
         if (mddev->gendisk) {
                 mutex_unlock(&disks_mutex);
@@ -3520,7 +3545,7 @@ static struct kobject *md_probe(dev_t dev, int *part, void *data)
         disk->private_data = mddev;
         disk->queue = mddev->queue;
         /* Allow extended partitions.  This makes the
-         * 'mdp' device redundant, but we can really
+         * 'mdp' device redundant, but we can't really
          * remove it now.
          */
         disk->flags |= GENHD_FL_EXT_DEVT;
@@ -3536,6 +3561,7 @@ static struct kobject *md_probe(dev_t dev, int *part, void *data)
                 kobject_uevent(&mddev->kobj, KOBJ_ADD);
                 mddev->sysfs_state = sysfs_get_dirent(mddev->kobj.sd, "array_state");
         }
+        mddev_put(mddev);
         return NULL;
 }
 
@@ -5054,6 +5080,9 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode,
 
 done_unlock:
 abort_unlock:
+        if (mddev->hold_active == UNTIL_IOCTL &&
+            err != -EINVAL)
+                mddev->hold_active = 0;
         mddev_unlock(mddev);
 
         return err;
@@ -5070,14 +5099,25 @@ static int md_open(struct block_device *bdev, fmode_t mode)
          * Succeed if we can lock the mddev, which confirms that
          * it isn't being stopped right now.
          */
-        mddev_t *mddev = bdev->bd_disk->private_data;
+        mddev_t *mddev = mddev_find(bdev->bd_dev);
         int err;
 
+        if (mddev->gendisk != bdev->bd_disk) {
+                /* we are racing with mddev_put which is discarding this
+                 * bd_disk.
+                 */
+                mddev_put(mddev);
+                /* Wait until bdev->bd_disk is definitely gone */
+                flush_scheduled_work();
+                /* Then retry the open from the top */
+                return -ERESTARTSYS;
+        }
+        BUG_ON(mddev != bdev->bd_disk->private_data);
+
         if ((err = mutex_lock_interruptible_nested(&mddev->reconfig_mutex, 1)))
                 goto out;
 
         err = 0;
-        mddev_get(mddev);
         atomic_inc(&mddev->openers);
         mddev_unlock(mddev);
 
@@ -6436,11 +6476,8 @@ static __exit void md_exit(void)
         unregister_sysctl_table(raid_table_header);
         remove_proc_entry("mdstat", NULL);
         for_each_mddev(mddev, tmp) {
-                struct gendisk *disk = mddev->gendisk;
-                if (!disk)
-                        continue;
                 export_array(mddev);
-                mddev_put(mddev);
+                mddev->hold_active = 0;
         }
 }