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Commit be8a9bc6 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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()
parents 0e536e25 63a4f065

drivers/md/dm.c

+16 −10
Original line number Diff line number Diff line
@@ -433,7 +433,6 @@ static int dm_blk_open(struct block_device *bdev, fmode_t mode) 


	dm_get(md);

	atomic_inc(&md->open_count);



out:

	spin_unlock(&_minor_lock);
@@ -442,16 +441,20 @@ out: 


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 @@ static void free_dev(struct mapped_device *md) 
	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 @@ static void free_dev(struct mapped_device *md) 
		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 @@ static void __dm_destroy(struct mapped_device *md, bool wait) 


	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);