On Tue, Sep 20, 2016 at 08:50:21AM -0400, jeffm@suse.com wrote:

From: Jeff Mahoney <redacted>

btrfs_rm_device frees the block device but then re-opens it using
the saved device name.  A race exists between the close and the
re-open that allows the block size to be changed.  The result
is getting stuck forever in the reclaim loop in __getblk_slow.

This patch moves the superblock cleanup before closing the block
device, which is also consistent with other callers.  We also don't
need a private copy of dev_name as the whole routine operates under
the uuid_mutex.

Signed-off-by: Jeff Mahoney <redacted>

Reviewed-by: David Sterba <dsterba@suse.com>