linux-ext4 - Re: [xfstests PATCH v4 0/5] new tests for writeback error reporting behavior

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Date:   Tue, 13 Jun 2017 06:36:14 -0400
From:   Jeff Layton <jlayton@...hat.com>
To:     Eryu Guan <eguan@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Al Viro <viro@...IV.linux.org.uk>, Jan Kara <jack@...e.cz>,
        tytso@....edu, axboe@...nel.dk, mawilcox@...rosoft.com,
        ross.zwisler@...ux.intel.com, corbet@....net,
        Chris Mason <clm@...com>, Josef Bacik <jbacik@...com>,
        David Sterba <dsterba@...e.com>,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        David Howells <dhowells@...hat.com>,
        linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
        linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-btrfs@...r.kernel.org, linux-block@...r.kernel.org
Subject: Re: [xfstests PATCH v4 0/5] new tests for writeback error reporting
 behavior

On Tue, 2017-06-13 at 16:32 +0800, Eryu Guan wrote:
> On Mon, Jun 12, 2017 at 08:42:08AM -0400, Jeff Layton wrote:
> > v4: respin set based on Eryu's comments
> > 
> > These tests are companion tests to the patchset I recently posted with
> > the cover letter:
> > 
> >     [PATCH v6 00/20] fs: enhanced writeback error reporting with errseq_t (pile #1)
> > 
> > This set just adds 3 new xfstests to test writeback behavior. One generic
> > filesystem test, one test for raw block devices, and one test for btrfs.
> > The tests work with dmerror to ensure that writeback fails, and then
> > tests how the kernel reports errors afterward.
> > 
> > xfs, ext2/3/4 and btrfs all pass on a kernel with the patchset above.
> 
> xfs, ext3/4 passed generic/999, btrfs passed btrfs/999 (with some local
> modifications, see reply to btrfs/999), but ext2 (using ext4 driver) and
> btrfs failed generic/999 on my host. (See test log at the end of mail.)
> 
> In the ext2 case, this test requires an external log device to run, but
> ext2 has no journal at all, I wonder if we should _notrun on ext2.
> 

Technically it doesn't _require_ an external log device, it just won't
pass on ext3/4 and xfs without one. Not sure how to convey that in a
_require directive here.

If you remove _require_logdev, it should pass on ext2 under the ext4.ko
driver as well.

ext2.ko still has issues though as the block device ends up getting
flagged with errors twice.

> btrfs doesn't support external log device either, it should not run this
> generic test either.
> 

Agreed. We just want it to run btrfs/999

> I think _require_logdev() should be updated too, to do a check on
> $FSTYP, only allows filesystems that have external log device support to
> continue to run.
> 

Ok.

> > 
> > The one comment I couldn't really address from earlier review is that
> > we don't have a great way for xfstests to tell what sort of error
> > reporting behavior it should expect from the running kernel. That
> > makes it difficult to tell whether failure is expected during a given
> > run.
> > 
> > Maybe that's OK though and we should just let unconverted filesystems
> > fail this test?
> 
> If there's really no good way to tell if current fs supports this new
> behavior, I think this is fine, strictly speaking, it's not a new
> feature anyway.
> 
> Thanks,
> Eryu
> 
> P.S. ext2 and btrfs failure in generic/999 run (I renumbered it to
> generic/441)
> 
> [root@...-x3550m3-05 xfstests]# ./check generic/441 generic/442
> FSTYP         -- ext2
> PLATFORM      -- Linux/x86_64 ibm-x3550m3-05 4.12.0-rc4.jlayton+
> MKFS_OPTIONS  -- /dev/sdc2
> MOUNT_OPTIONS -- -o acl,user_xattr -o context=system_u:object_r:root_t:s0 /dev/sdc2 /mnt/testarea/scratch
> 
> generic/441 4s ... - output mismatch (see /root/xfstests/results//generic/441.out.bad)
>     --- tests/generic/441.out   2017-06-13 15:52:09.928413126 +0800
>     +++ /root/xfstests/results//generic/441.out.bad     2017-06-13 16:21:41.414112226 +0800
>     @@ -1,3 +1,3 @@
>      QA output created by 441
>      Format and mount
>     -Test passed!
>     +Third fsync on fd[0] failed: Input/output error
>     ...
>     (Run 'diff -u tests/generic/441.out /root/xfstests/results//generic/441.out.bad'  to see the entire diff)
> 

That means that it returned EIO on fsync when the error should have been
cleared. I'll see if I can reproduce it on my setup.

> [root@...-x3550m3-05 xfstests]# ./check generic/441 generic/442
> FSTYP         -- btrfs
> PLATFORM      -- Linux/x86_64 ibm-x3550m3-05 4.12.0-rc4.jlayton+
> MKFS_OPTIONS  -- /dev/sdc2
> MOUNT_OPTIONS -- -o context=system_u:object_r:root_t:s0 /dev/sdc2 /mnt/testarea/scratch
> 
> generic/441 4s ... - output mismatch (see /root/xfstests/results//generic/441.out.bad)
>     --- tests/generic/441.out   2017-06-13 15:52:09.928413126 +0800
>     +++ /root/xfstests/results//generic/441.out.bad     2017-06-13 16:25:17.483273992 +0800
>     @@ -1,3 +1,3 @@
>      QA output created by 441
>      Format and mount
>     -Test passed!
>     +Third fsync on fd[0] failed: Read-only file system
>     ...
>     (Run 'diff -u tests/generic/441.out /root/xfstests/results//generic/441.out.bad'  to see the entire diff)

That's expected on btrfs. It needs btrfs/999 test to do this correctly.

> > 
> > Jeff Layton (5):
> >   generic: add a writeback error handling test
> >   ext4: allow ext4 to use $SCRATCH_LOGDEV
> >   generic: test writeback error handling on dmerror devices
> >   ext3: allow it to put journal on a separate device when doing
> >     scratch_mkfs
> >   btrfs: make a btrfs version of writeback error reporting test
> > 
> >  .gitignore                 |   1 +
> >  common/dmerror             |  13 ++-
> >  common/rc                  |  14 ++-
> >  doc/auxiliary-programs.txt |  16 ++++
> >  src/Makefile               |   2 +-
> >  src/dmerror                |  44 +++++++++
> >  src/fsync-err.c            | 223 +++++++++++++++++++++++++++++++++++++++++++++
> >  tests/btrfs/999            |  93 +++++++++++++++++++
> >  tests/btrfs/group          |   1 +
> >  tests/generic/998          |  64 +++++++++++++
> >  tests/generic/998.out      |   2 +
> >  tests/generic/999          |  77 ++++++++++++++++
> >  tests/generic/999.out      |   3 +
> >  tests/generic/group        |   2 +
> >  14 files changed, 548 insertions(+), 7 deletions(-)
> >  create mode 100755 src/dmerror
> >  create mode 100644 src/fsync-err.c
> >  create mode 100755 tests/btrfs/999
> >  create mode 100755 tests/generic/998
> >  create mode 100644 tests/generic/998.out
> >  create mode 100755 tests/generic/999
> >  create mode 100644 tests/generic/999.out
> > 
> > -- 
> > 2.13.0
> > 

-- 
Jeff Layton <jlayton@...hat.com>