[PATCH] dm: core: put device mapper block device synchronously

[Ming Lei <ming.lei@redhat.com>]

'dmsetup remove_all' actually depends on sync bdev release since
dm_lock_for_deletion() may return -EBUSY if the open count is > 0, and the
open count is dropped in dm_blk_close().

So if dm_blk_close() is delayed because of fput(), this device mapper
device is skipped in remove_all, and cause regression.

Fix the issue by using __fput_sync().

Reported-by: Zhong Changhui <czhong@redhat.com>
Fixes: a28d893eb327 ("md: port block device access to file")
Suggested-by: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/md/dm.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 56aa2a8b9d71..93f3d28b0f03 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -765,7 +765,7 @@ static struct table_device *open_table_device(struct mapped_device *md,
 	return td;
 
 out_blkdev_put:
-	fput(bdev_file);
+	__fput_sync(bdev_file);
 out_free_td:
 	kfree(td);
 	return ERR_PTR(r);
@@ -778,7 +778,7 @@ static void close_table_device(struct table_device *td, struct mapped_device *md
 {
 	if (md->disk->slave_dir)
 		bd_unlink_disk_holder(td->dm_dev.bdev, md->disk);
-	fput(td->dm_dev.bdev_file);
+	__fput_sync(td->dm_dev.bdev_file);
 	put_dax(td->dm_dev.dax_dev);
 	list_del(&td->list);
 	kfree(td);
-- 
2.44.0