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; -- 1.7.1 _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
