[PATCH] device-mapper multipath: Avoid possible suspension deadlock

To avoid deadlock when suspending a multipath device after all its paths have
failed, stop queueing any I/O that is about to fail *before* calling
freeze_bdev instead of after.

Instead of setting a multipath 'suspended' flag which would have to be reset
if an error occurs during the process, save the previous queueing state and
leave userspace to restore if it wishes.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>