commit cdd9eefd upstream.

Commit 0244756e ("ufs: sb mutex merge + mutex_destroy") generated
deadlocks in read/write mode on mkdir.

This patch partially reverts it keeping fixes by Andrew Morton and
mutex_destroy()

[AV: fixed a missing bit in ufs_remount()]
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Reported-by: Ian Campbell <ian.campbell@citrix.com>
Suggested-by: Jan Kara <jack@suse.cz>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Evgeniy Dushistov <dushistov@mail.ru>
Cc: Alexey Khoroshilov <khoroshilov@ispras.ru>
Cc: Roger Pau Monne <roger.pau@citrix.com>
Cc: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>