lkml.org 
[lkml]   [2010]   [Jul]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/2] blkdev: check for valid request queue before issuing flush
On 2010-07-13 09:50, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> Issuing a blkdev_issue_flush() on an unconfigured loop device causes a panic as
> q->make_request_fn is not configured. This can occur when trying to mount the
> unconfigured loop device as an XFS filesystem. There are no guards that catch
> the bio before the request function is called because we don't add a payload to
> the bio. Instead, manually check this case as soon as we have a pointer to the
> queue to flush.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
> block/blk-barrier.c | 9 +++++++++
> 1 files changed, 9 insertions(+), 0 deletions(-)
>
> diff --git a/block/blk-barrier.c b/block/blk-barrier.c
> index 0d710c9..0fd766e 100644
> --- a/block/blk-barrier.c
> +++ b/block/blk-barrier.c
> @@ -319,6 +319,15 @@ int blkdev_issue_flush(struct block_device *bdev, gfp_t gfp_mask,
> if (!q)
> return -ENXIO;
>
> + /*
> + * some block devices may not have their queue correctly set up here
> + * (e.g. loop device without a backing file) and so issuing a flush
> + * here will panic. Ensure there is a request function before issuing
> + * the barrier.
> + */
> + if (!q->make_request_fn)
> + return -ENXIO;
> +
> bio = bio_alloc(gfp_mask, 0);
> bio->bi_end_io = bio_end_empty_barrier;
> bio->bi_bdev = bdev;

This may appear ugly, but I think the patch is fine since there's not
much we can do about the loop crap (outside of changing how you do
setup/configure of it).

I'll apply this, thanks.

--
Jens Axboe



\
 
 \ /
  Last update: 2010-07-13 14:57    [W:0.047 / U:1.292 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site