[PATCHSET v2 0/3] fstests: fix some hangs in crash recovery

["Darrick J. Wong" <djwong@kernel.org>]

Hi all,

There are several tests in fstests (generic/019, generic/388,
generic/475, xfs/057, etc.) that test filesystem crash recovery by
starting a loop that kicks off a filesystem exerciser, waits a few
seconds, and offlines the filesystem somehow.  Some of them use the
block layer's error injector, some use dm-error, and some use the
shutdown ioctl.

The crash tests that employ error injection have the unfortunate trait
of causing occasional livelocks when tested against XFS because XFS
allows administrators to configure the filesystem to retry some failed
writes indefinitely.  If the offlining races with a full log trying to
update the filesystem, the fs will hang forever.  Fix this by allowing
XFS to go offline immediately.

While we're at it, fix the dmesg scrapers so they don't trip over XFS
reporting these IO errors as internal errors.

v2: add hch reviews

If you're going to start using this mess, you probably ought to just
pull from my git trees, which are linked below.

This is an extraordinary way to destroy everything.  Enjoy!
Comments and questions are, as always, welcome.

--D

fstests git tree:
https://git.kernel.org/cgit/linux/kernel/git/djwong/xfstests-dev.git/log/?h=fix-shutdown-test-hangs
---
 check                    |    1 +
 common/dmerror           |    4 ++++
 common/fail_make_request |    1 +
 common/rc                |   50 +++++++++++++++++++++++++++++++++++++++++-----
 common/xfs               |   38 ++++++++++++++++++++++++++++++++++-
 tests/xfs/006.out        |    6 +++---
 tests/xfs/264.out        |   12 ++++++-----
 7 files changed, 97 insertions(+), 15 deletions(-)