md: only count actual openers as access which prevent a 'stop'
Open isn't the only thing that increments ->active. e.g. reading
/proc/mdstat will increment it briefly. So to avoid false positives
in testing for concurrent access, introduce a new counter that counts
just the number of times the md device it open.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 4bfbc19..450f30b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -273,6 +273,7 @@
INIT_LIST_HEAD(&new->all_mddevs);
init_timer(&new->safemode_timer);
atomic_set(&new->active, 1);
+ atomic_set(&new->openers, 0);
spin_lock_init(&new->write_lock);
init_waitqueue_head(&new->sb_wait);
init_waitqueue_head(&new->recovery_wait);
@@ -2695,14 +2696,14 @@
break;
case clear:
/* stopping an active array */
- if (atomic_read(&mddev->active) > 1)
+ if (atomic_read(&mddev->openers) > 0)
return -EBUSY;
err = do_md_stop(mddev, 0, 0);
break;
case inactive:
/* stopping an active array */
if (mddev->pers) {
- if (atomic_read(&mddev->active) > 1)
+ if (atomic_read(&mddev->openers) > 0)
return -EBUSY;
err = do_md_stop(mddev, 2, 0);
} else
@@ -3816,7 +3817,7 @@
int err = 0;
struct gendisk *disk = mddev->gendisk;
- if (atomic_read(&mddev->active) > 1 + is_open) {
+ if (atomic_read(&mddev->openers) > is_open) {
printk("md: %s still in use.\n",mdname(mddev));
return -EBUSY;
}
@@ -5014,6 +5015,7 @@
err = 0;
mddev_get(mddev);
+ atomic_inc(&mddev->openers);
mddev_unlock(mddev);
check_disk_change(inode->i_bdev);
@@ -5026,6 +5028,7 @@
mddev_t *mddev = inode->i_bdev->bd_disk->private_data;
BUG_ON(!mddev);
+ atomic_dec(&mddev->openers);
mddev_put(mddev);
return 0;
diff --git a/include/linux/raid/md_k.h b/include/linux/raid/md_k.h
index 6f72b47..4bef479 100644
--- a/include/linux/raid/md_k.h
+++ b/include/linux/raid/md_k.h
@@ -215,7 +215,8 @@
int in_sync; /* know to not need resync */
struct mutex reconfig_mutex;
- atomic_t active;
+ atomic_t active; /* general refcount */
+ atomic_t openers; /* number of active opens */
int changed; /* true if we might need to reread partition info */
int degraded; /* whether md should consider