dm: separate device deletion from dm_put()

Commit Message

Kiyoshi Ueda March 8, 2010, 4:42 a.m. UTC

None

Patch

Index: 2.6.33/drivers/md/dm-ioctl.c
===================================================================
--- 2.6.33.orig/drivers/md/dm-ioctl.c
+++ 2.6.33/drivers/md/dm-ioctl.c
@@ -252,6 +252,7 @@  static void dm_hash_remove_all(int keep_
 	int i, dev_skipped, dev_removed;
 	struct hash_cell *hc;
 	struct list_head *tmp, *n;
+	struct mapped_device *md;
 
 	down_write(&_hash_lock);
 
@@ -260,13 +261,14 @@  retry:
 	for (i = 0; i < NUM_BUCKETS; i++) {
 		list_for_each_safe (tmp, n, _name_buckets + i) {
 			hc = list_entry(tmp, struct hash_cell, name_list);
+			md = hc->md;
 
-			if (keep_open_devices &&
-			    dm_lock_for_deletion(hc->md)) {
+			if (keep_open_devices && dm_lock_for_deletion(md)) {
 				dev_skipped++;
 				continue;
 			}
 			__hash_remove(hc);
+			dm_destroy(md);
 			dev_removed = 1;
 		}
 	}
@@ -640,6 +642,7 @@  static int dev_create(struct dm_ioctl *p
 	r = dm_hash_insert(param->name, *param->uuid ? param->uuid : NULL, md);
 	if (r) {
 		dm_put(md);
+		dm_destroy(md);
 		return r;
 	}
 
@@ -742,6 +745,7 @@  static int dev_remove(struct dm_ioctl *p
 		param->flags |= DM_UEVENT_GENERATED_FLAG;
 
 	dm_put(md);
+	dm_destroy(md);
 	return 0;
 }
 
Index: 2.6.33/drivers/md/dm.c
===================================================================
--- 2.6.33.orig/drivers/md/dm.c
+++ 2.6.33/drivers/md/dm.c
@@ -2175,6 +2175,7 @@  void dm_set_mdptr(struct mapped_device *
 void dm_get(struct mapped_device *md)
 {
 	atomic_inc(&md->holders);
+	BUG_ON(test_bit(DMF_FREEING, &md->flags));
 }
 
 const char *dm_device_name(struct mapped_device *md)
@@ -2183,27 +2184,41 @@  const char *dm_device_name(struct mapped
 }
 EXPORT_SYMBOL_GPL(dm_device_name);
 
-void dm_put(struct mapped_device *md)
+void dm_destroy(struct mapped_device *md)
 {
 	struct dm_table *map;
 
-	BUG_ON(test_bit(DMF_FREEING, &md->flags));
+	might_sleep();
 
-	if (atomic_dec_and_lock(&md->holders, &_minor_lock)) {
-		map = dm_get_live_table(md);
-		idr_replace(&_minor_idr, MINOR_ALLOCED,
-			    MINOR(disk_devt(dm_disk(md))));
-		set_bit(DMF_FREEING, &md->flags);
-		spin_unlock(&_minor_lock);
-		if (!dm_suspended_md(md)) {
-			dm_table_presuspend_targets(map);
-			dm_table_postsuspend_targets(map);
-		}
-		dm_sysfs_exit(md);
-		dm_table_put(map);
-		dm_table_destroy(__unbind(md));
-		free_dev(md);
+	spin_lock(&_minor_lock);
+	map = dm_get_live_table(md);
+	idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md))));
+	set_bit(DMF_FREEING, &md->flags);
+	spin_unlock(&_minor_lock);
+
+	if (!dm_suspended_md(md)) {
+		dm_table_presuspend_targets(map);
+		dm_table_postsuspend_targets(map);
 	}
+
+	/*
+	 * Rare but there may be I/O requests still going to complete,
+	 * for example.  Wait for all references to disappear.
+	 * No one shouldn't increment the reference count of the mapped_device,
+	 * after the mapped_device becomes DMF_FREEING state.
+	 */
+	while (atomic_read(&md->holders))
+		msleep(1);
+
+	dm_sysfs_exit(md);
+	dm_table_put(map);
+	dm_table_destroy(__unbind(md));
+	free_dev(md);
+}
+
+void dm_put(struct mapped_device *md)
+{
+	atomic_dec(&md->holders);
 }
 EXPORT_SYMBOL_GPL(dm_put);
 
Index: 2.6.33/drivers/md/dm.h
===================================================================
--- 2.6.33.orig/drivers/md/dm.h
+++ 2.6.33/drivers/md/dm.h
@@ -122,6 +122,10 @@  void dm_linear_exit(void);
 int dm_stripe_init(void);
 void dm_stripe_exit(void);
 
+/*
+ * mapped_device operations
+ */
+void dm_destroy(struct mapped_device *md);
 int dm_open_count(struct mapped_device *md);
 int dm_lock_for_deletion(struct mapped_device *md);