Re: [PATCH] aoe: end barrier bios with EOPNOTSUPP

Jens Axboe
2009-09-10T20:29:07Z

On Thu, Sep 10 2009, Ed Cashin wrote:
> 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.
>
> Signed-off-by: Ed L. Cashin <ecashin@coraid.com>
> ---
> drivers/block/aoe/aoeblk.c | 3 +++
> 1 files changed, 3 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
> index 2307a27..22efb33 100644
> --- a/drivers/block/aoe/aoeblk.c
> +++ b/drivers/block/aoe/aoeblk.c
> @@ -172,6 +172,9 @@ aoeblk_make_request(struct request_queue *q, struct bio *bio)
> BUG();
> bio_endio(bio, -ENXIO);
> return 0;
> + } else if (bio_barrier(bio)) {
> + bio_endio(bio, -EOPNOTSUPP);
> + return 0;
> } else if (bio->bi_io_vec == NULL) {
> printk(KERN_ERR "aoe: bi_io_vec is NULL\n");
> BUG();
> --
> 1.5.6.5

I have applied this with a note that proper barrier support is coming.

--
Jens Axboe