[PATCH 0/2] Graceful failures for XFS on an unconfigured loop device

[Dave Chinner <david@xxxxxxxxxxxxx>]

Run:

# mount -t xfs /dev/loop0 /mnt

on a freshly booted system and it won't like you anymore. This series fixes
the broken XFS error handling for dispatch errors on synchronous reads that
causes a hang, and then patches the panic it uncovers. With these two patches,
the mount fails gracefully.

The modification to blkdev_issue_flush is probably not the right place to check
for a valid q->make_request_fn. This just patches around the problem in the
simplest way possible. There's probably a better way to fix it - personally I'd
prefer that we don't even get to mounting a filesystem on an unconfigured loop
device...