dm: restore synchronous close of device mapper block device

'dmsetup remove' and 'dmsetup remove_all' require synchronous bdev
release. Otherwise dm_lock_for_deletion() may return -EBUSY if the open
count is > 0, because the open count is dropped in dm_blk_close()
which occurs after fput() completes.

So if dm_blk_close() is delayed because of asynchronous fput(), this
device mapper device is skipped during remove, which is a regression.

Fix the issue by using __fput_sync().

Also, DM device removal has long supported being made asynchronous by
setting the DMF_DEFERRED_REMOVE flag on the DM device. So leverage
using async fput() in close_table_device() if DMF_DEFERRED_REMOVE flag
is set.

Reported-by: Zhong Changhui <[email protected]>
Fixes: a28d893eb327 ("md: port block device access to file")
Suggested-by: Christian Brauner <[email protected]>
Signed-off-by: Ming Lei <[email protected]>
[snitzer: editted commit header, use fput() if DMF_DEFERRED_REMOVE set]
Signed-off-by: Mike Snitzer <[email protected]>

0 files changed, 0 insertions, 0 deletions