dm: separate device deletion from dm_put

[deliverable/linux.git] / drivers / md / dm.c

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index ba6934c3e2c5ecf0d2dbed5d560a97327c8bf774..a503b95ecbfb515e863e7539a5f516bbef3e9fe6 100644 (file)
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -20,6 +20,7 @@
 #include <linux/slab.h>
 #include <linux/idr.h>
 #include <linux/hdreg.h>
+#include <linux/delay.h>
 
 #include <trace/events/block.h>
 
@@ -2171,6 +2172,7 @@ void dm_set_mdptr(struct mapped_device *md, void *ptr)
 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)
@@ -2179,27 +2181,55 @@ const char *dm_device_name(struct mapped_device *md)
 }
 EXPORT_SYMBOL_GPL(dm_device_name);
 
-void dm_put(struct mapped_device *md)
+static void __dm_destroy(struct mapped_device *md, bool wait)
 {
        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 should increment the reference count of the mapped_device,
+        * after the mapped_device state becomes DMF_FREEING.
+        */
+       if (wait)
+               while (atomic_read(&md->holders))
+                       msleep(1);
+       else if (atomic_read(&md->holders))
+               DMWARN("%s: Forcibly removing mapped_device still in use! (%d users)",
+                      dm_device_name(md), atomic_read(&md->holders));
+
+       dm_sysfs_exit(md);
+       dm_table_put(map);
+       dm_table_destroy(__unbind(md));
+       free_dev(md);
+}
+
+void dm_destroy(struct mapped_device *md)
+{
+       __dm_destroy(md, true);
+}
+
+void dm_destroy_immediate(struct mapped_device *md)
+{
+       __dm_destroy(md, false);
+}
+
+void dm_put(struct mapped_device *md)
+{
+       atomic_dec(&md->holders);
 }
 EXPORT_SYMBOL_GPL(dm_put);