Re: [PATCH v3] tests/xfs: check available blocks after log recovery on ro mount

[Zorro Lang <zlang@redhat.com>]

On Tue, Aug 24, 2021 at 08:14:28AM -0700, Darrick J. Wong wrote:
> On Tue, Aug 24, 2021 at 01:04:36PM +0800, Murphy Zhou wrote:
> > And followed by a rw mount.
> > 
> > Suggested-by:  Donald Douwsma <ddouwsma@redhat.com>
> > Reviewed-by: Darrick J. Wong <djwong@kernel.org>
> > Signed-off-by: Murphy Zhou <xzhou@redhat.com>
> > ---
> > 
> > Thanks Darrick very much for reviewing!
> > 
> > v2:
> >    Add explaination of the issue
> >    add xfs_force_bdev data $SCRATCH_MNT
> >    use DF_PROG
> >    Re numbered this test
> > v3:
> >    Add _require_scratch_shutdown
> >    Use _get_available_space
> >    Explain why does not use _scratch_mount
> > 
> >  tests/xfs/999     | 65 +++++++++++++++++++++++++++++++++++++++++++++++
> >  tests/xfs/999.out |  2 ++
> >  2 files changed, 67 insertions(+)
> >  create mode 100755 tests/xfs/999
> >  create mode 100644 tests/xfs/999.out
> > 
> > diff --git a/tests/xfs/999 b/tests/xfs/999
> > new file mode 100755
> > index 00000000..0ce9989b
> > --- /dev/null
> > +++ b/tests/xfs/999
> > @@ -0,0 +1,65 @@
> > +#! /bin/bash
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Copyright (c) 2021 RedHat All Rights Reserved.
> > +#
> > +# FS QA Test 999
> > +#
> > +# Testcase for kernel commit:
> > +#   50d25484bebe xfs: sync lazy sb accounting on quiesce of read-only mounts
> > +#
> > +# After shutdown and readonly mount, a following read-write mount would
> > +# get wrong number of available blocks. This is caused by unmounting the log
> > +# on a readonly filesystem doesn't log the sb counters.
> > +#
> > +. ./common/preamble
> > +_begin_fstest shutdown auto quick
> > +
> > +# real QA test starts here
> > +
> > +_supported_fs xfs
> > +_require_scratch
> > +_require_scratch_shutdown
> > +
> > +_scratch_mkfs > $seqres.full 2>&1
> > +# Don't use _scratch_mount because we need to mount without SELinux context
> > +# to reproduce this issue. If we mount with SELinux context, this testcase
> > +# is not reproducing the original issue.
> > +mount $SCRATCH_DEV $SCRATCH_MNT
> 
> This mount will fail if the test runner configured an external log or a
> realtime device, because you didn't specify those devices to the mount
> call.  Either this needs _require_nonexternal or $(_scratch_options
> mount) needs to be injected into the command line.

I think I know why Xiong said _scratch_mount can't reproduce this bug.

Before this patch v3, he tried to find the xfs corruption by using $DF_PROG $SCRATCH_MNT
before&after xfs_repair.

If we use _scratch_mount, new files we create won't contains SELinux label
in xfs inode attrfork. The corruption comes from sb_ifree (free inodes):
  Phase 2 - using internal log
        - zero log...
        - scan filesystem freespace and inode maps...
  sb_ifree 61, counted 60

But if we don't use _scratch_mount, the corruption comes from sb_fdblocks(free blocks):
  Phase 2 - using internal log
        - zero log...
        - scan filesystem freespace and inode maps...
  sb_fdblocks 130086290, counted 131007896

So if he use _scratch_mount, he can't get different available blocks by
$DF_PROG $SCRATCH_MNT, before&after xfs_repair. Due to the corrupted thing
is sb_ifree.

But I still can't understand one thing, even if do *not* use _scratch_mount, the attr(selinux label)
is local(short) format[1], didn't take more blocks. What takes more blocks, cause later
sb_fdblocks corruption?

Thanks,
Zorro

[1]
...
core.aformat = 1 (local)
...
u3 = (empty)
a.sfattr.hdr.totsize = 51
a.sfattr.hdr.count = 1
a.sfattr.list[0].namelen = 7
a.sfattr.list[0].valuelen = 37
a.sfattr.list[0].root = 0
a.sfattr.list[0].secure = 1
a.sfattr.list[0].name = "selinux"
a.sfattr.list[0].value = "unconfined_u:object_r:unlabeled_t:s0\000"


> 
> --D
> 
> > +_xfs_force_bdev data $SCRATCH_MNT
> > +
> > +# Write test file
> > +ls > $SCRATCH_MNT/testfile
> > +$DF_PROG $SCRATCH_MNT >> $seqres.full 2>&1
> > +
> > +# Shutdown
> > +$XFS_IO_PROG -x -c "shutdown -f" $SCRATCH_MNT
> > +
> > +# Mount ReadOnly
> > +_scratch_unmount
> > +_scratch_mount -oro
> > +$DF_PROG $SCRATCH_MNT >> $seqres.full 2>&1
> > +# Umount and mount rw
> > +_scratch_unmount
> > +_scratch_mount
> > +
> > +# Get fdblocks before repair
> > +fdb1=$(_get_available_space $SCRATCH_MNT)
> > +_scratch_unmount
> > +
> > +# Repair
> > +_repair_scratch_fs >> $seqres.full 2>&1
> > +
> > +# Re-mount
> > +_scratch_mount
> > +
> > +# Get fdblocks after repair
> > +fdb2=$(_get_available_space $SCRATCH_MNT)
> > +
> > +echo fdb1 $fdb1 fdb2 $fdb2 >> $seqres.full 2>&1
> > +
> > +[ $fdb1 -ne $fdb2 ] && echo Wrong fdblocks: $fdb1 and $fdb2
> > +
> > +# success, all done
> > +echo "Silence is golden"
> > +status=0
> > +exit
> > diff --git a/tests/xfs/999.out b/tests/xfs/999.out
> > new file mode 100644
> > index 00000000..3b276ca8
> > --- /dev/null
> > +++ b/tests/xfs/999.out
> > @@ -0,0 +1,2 @@
> > +QA output created by 999
> > +Silence is golden
> > -- 
> > 2.20.1
> > 
>