Re: [PATCH] overlay: add test for rename of lower symlink with NOATIME attr

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On Wed, Sep 20, 2023 at 6:14 PM Zorro Lang <zlang@xxxxxxxxxx> wrote:
>
> On Wed, Sep 20, 2023 at 04:03:55PM +0300, Amir Goldstein wrote:
> > A test for a regression from v5.15 reported by Ruiwen Zhao:
> > https://lore.kernel.org/linux-unionfs/CAKd=y5Hpg7J2gxrFT02F94o=FM9QvGp=kcH1Grctx8HzFYvpiA@xxxxxxxxxxxxxx/
> >
> > Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
> > ---
> >
> > Zorro,
> >
> > This is a test for a regression in kernel v5.15.
> > The fix was merged for 6.6-rc2 and has been picked for
> > the upcoming LTS releases 5.15, 6.1, 6.5.
> >
> > The reproducer only manifests the bug in fs that inherit noatime flag,
> > namely ext4, btrfs, ... but not xfs.
> >
> > The test does _notrun on xfs for that reason.
> >
> > Thanks,
> > Amir.
> >
> >  tests/overlay/082     | 68 +++++++++++++++++++++++++++++++++++++++++++
> >  tests/overlay/082.out |  2 ++
> >  2 files changed, 70 insertions(+)
> >  create mode 100755 tests/overlay/082
> >  create mode 100644 tests/overlay/082.out
> >
> > diff --git a/tests/overlay/082 b/tests/overlay/082
> > new file mode 100755
> > index 00000000..abea3c2b
> > --- /dev/null
> > +++ b/tests/overlay/082
> > @@ -0,0 +1,68 @@
> > +#! /bin/bash
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Copyright (C) 2023 CTERA Networks. All Rights Reserved.
> > +#
> > +# FS QA Test 082
> > +#
> > +# kernel commit 72db82115d2b ("ovl: copy up sync/noatime fileattr flags")
> > +# from v5.15 introduced a regression.
> > +#
> > +. ./common/preamble
> > +_begin_fstest auto quick
> > +
> > +# Import common functions.
> > +. ./common/filter
> > +
> > +# real QA test starts here
> > +_supported_fs overlay
> > +_fixed_by_kernel_commit ab048302026d \
> > +     "ovl: fix failed copyup of fileattr on a symlink"
> > +
> > +_require_scratch
> > +_require_chattr A
> > +
> > +# remove all files from previous runs
> > +_scratch_mkfs
> > +
> > +# prepare lower test dir with NOATIME flag
> > +lowerdir=$OVL_BASE_SCRATCH_MNT/$OVL_LOWER
> > +mkdir -p $lowerdir/testdir
> > +$CHATTR_PROG +A $lowerdir/testdir >> $seqres.full 2>&1 ||
> > +     _notrun "base fs $OVL_BASE_FSTYP does not support No_Atime flag"
> > +
> > +# The NOATIME is inheritted to children symlink in ext4/fs2fs
> > +# (and on tmpfs on recent kernels).
> > +# The overlayfs test will not fail unless base fs is
> > +# one of those filesystems.
> > +#
> > +# The problem with this inheritence is that the NOATIME flag is inheritted
> > +# to a symlink and the flag does take effect, but there is no way to query
> > +# the flag (lsattr) or change it (chattr) on a symlink, so overlayfs will
> > +# fail when trying to copy up NOATIME flag from lower to upper symlink.
> > +#
> > +touch $lowerdir/testdir/foo
> > +ln -sf foo $lowerdir/testdir/lnk
> > +
> > +$LSATTR_PROG -l $lowerdir/testdir/foo >> $seqres.full 2>&1
> > +$LSATTR_PROG -l $lowerdir/testdir/foo | grep -q No_Atime || \
> > +     _notrun "base fs $OVL_BASE_FSTYP does not inherit No_Atime flag"
> > +
> > +before=$(stat -c %x $lowerdir/testdir/lnk)
> > +echo "symlink atime before readlink: $before" >> $seqres.full 2>&1
> > +cat $lowerdir/testdir/lnk
> > +after=$(stat -c %x $lowerdir/testdir/lnk)
> > +echo "symlink atime after readlink: $after" >> $seqres.full 2>&1
> > +
> > +[ "$before" == "$after" ] || \
> > +     _notrun "base fs $OVL_BASE_FSTYP does not inherit No_Atime flag on symlink"
> > +
> > +# mounting overlay
> > +_scratch_mount
> > +
> > +# moving symlink will try to copy up lower symlink flags
> > +mv $SCRATCH_MNT/testdir/lnk $SCRATCH_MNT/
>
> Lots of above codes are checking if the underlying fs supports No_Atime (and inherit),
> and _notrun if not support. How about do these checking steps in a require_*
> function locally or in common/, likes _require_noatime_inheritance(). And we also
> can let _require_chattr accept one more argument to specify a test directory.
>

ok.

> The "mv ..." command looks like the final testing step. If there's not that bug,
> nothing happen, but I'm wondering what should happen if there's a bug?

mv fails with error ENXIO, see linked bug report in commit message.

Thanks,
Amir.




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