tree 9051bbd875dd96d8d75ccf2dfc228e912edfeb50
parent 01edede41e352e4879a89cdc5468f72ffc89b713
author Ed Cashin <ecashin@coraid.com> 1252614647 +0200
committer Jens Axboe <jens.axboe@oracle.com> 1252909492 +0200

aoe: end barrier bios with EOPNOTSUPP

BugLink: http://bugzilla.kernel.org/show_bug.cgi?id=13942

Bruno Premont noticed that aoe throws a BUG during umount of an XFS in
2.6.31:

[ 5259.349897] aoe: bi_io_vec is NULL
[ 5259.349940] ------------[ cut here ]------------
[ 5259.349958] kernel BUG at /usr/src/linux-2.6/drivers/block/aoe/aoeblk.c:177!
[ 5259.349990] invalid opcode: 0000 [#1]

The bio in question is a barrier.  Jens Axboe suggested that such bios
need to be recognized and ended with -EOPNOTSUPP by any driver that
provides its own ->make_request_fn handler and does not handle
barriers.

In testing the changes below eliminate the BUG.

(Better would be real barrier support, something that Ed says he'll add
for later in the .32 cycle. For now, this at least gets rid of a bug
with crashing on an empty barrier. Jens)

Signed-off-by: Ed L. Cashin <ecashin@coraid.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>