Merge tag 'dm-4.0-fix-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm
Pull device mapper fix from Mike Snitzer:
"Fix DM core device cleanup regression -- due to a latent race that was
exposed by the bdi changes that were introduced during the 4.0 merge"
* tag 'dm-4.0-fix-2' of git://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm:
dm: fix add_disk() NULL pointer due to race with free_dev()
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 9b641b3..8001fe9 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -433,7 +433,6 @@
dm_get(md);
atomic_inc(&md->open_count);
-
out:
spin_unlock(&_minor_lock);
@@ -442,16 +441,20 @@
static void dm_blk_close(struct gendisk *disk, fmode_t mode)
{
- struct mapped_device *md = disk->private_data;
+ struct mapped_device *md;
spin_lock(&_minor_lock);
+ md = disk->private_data;
+ if (WARN_ON(!md))
+ goto out;
+
if (atomic_dec_and_test(&md->open_count) &&
(test_bit(DMF_DEFERRED_REMOVE, &md->flags)))
queue_work(deferred_remove_workqueue, &deferred_remove_work);
dm_put(md);
-
+out:
spin_unlock(&_minor_lock);
}
@@ -2241,7 +2244,6 @@
int minor = MINOR(disk_devt(md->disk));
unlock_fs(md);
- bdput(md->bdev);
destroy_workqueue(md->wq);
if (md->kworker_task)
@@ -2252,19 +2254,22 @@
mempool_destroy(md->rq_pool);
if (md->bs)
bioset_free(md->bs);
- blk_integrity_unregister(md->disk);
- del_gendisk(md->disk);
+
cleanup_srcu_struct(&md->io_barrier);
free_table_devices(&md->table_devices);
- free_minor(minor);
+ dm_stats_cleanup(&md->stats);
spin_lock(&_minor_lock);
md->disk->private_data = NULL;
spin_unlock(&_minor_lock);
-
+ if (blk_get_integrity(md->disk))
+ blk_integrity_unregister(md->disk);
+ del_gendisk(md->disk);
put_disk(md->disk);
blk_cleanup_queue(md->queue);
- dm_stats_cleanup(&md->stats);
+ bdput(md->bdev);
+ free_minor(minor);
+
module_put(THIS_MODULE);
kfree(md);
}
@@ -2642,8 +2647,9 @@
might_sleep();
- spin_lock(&_minor_lock);
map = dm_get_live_table(md, &srcu_idx);
+
+ spin_lock(&_minor_lock);
idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md))));
set_bit(DMF_FREEING, &md->flags);
spin_unlock(&_minor_lock);