On 2010-07-13 09:50, Dave Chinner wrote: > From: Dave Chinner <dchinner@xxxxxxxxxx> > > 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@xxxxxxxxxx> > --- > 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 _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
