[2/3] xfs: test correct propagation of rt extent size hints on rtinherit dirs

Commit Message

Darrick J. Wong Sept. 1, 2021, 12:11 a.m. UTC

From: Darrick J. Wong <[e-mail]>

This is a regression test for the following fixes:

 xfs: standardize extent size hint validation
 xfs: validate extsz hints against rt extent size when rtinherit is set
 mkfs: validate rt extent size hint when rtinherit is set

These patches fix inadequate rtextsize alignment validation of extent
size hints on directories with the rtinherit and extszinherit flags set.

Signed-off-by: Darrick J. Wong <[e-mail]>
---
 tests/xfs/774     |   80 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 tests/xfs/774.out |    5 +++
 tests/xfs/776     |   57 ++++++++++++++++++++++++++++++++++++++
 tests/xfs/776.out |    5 +++
 4 files changed, 147 insertions(+)
 create mode 100755 tests/xfs/774
 create mode 100644 tests/xfs/774.out
 create mode 100755 tests/xfs/776
 create mode 100644 tests/xfs/776.out

Comments

Eryu Guan Sept. 5, 2021, 2:35 p.m. UTC | #1

On Tue, Aug 31, 2021 at 05:11:35PM -0700, Darrick J. Wong wrote:
> From: Darrick J. Wong <[e-mail]>
> 
> This is a regression test for the following fixes:
> 
>  xfs: standardize extent size hint validation
>  xfs: validate extsz hints against rt extent size when rtinherit is set
>  mkfs: validate rt extent size hint when rtinherit is set
> 
> These patches fix inadequate rtextsize alignment validation of extent
> size hints on directories with the rtinherit and extszinherit flags set.
> 
> Signed-off-by: Darrick J. Wong <[e-mail]>
> ---
>  tests/xfs/774     |   80 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  tests/xfs/774.out |    5 +++
>  tests/xfs/776     |   57 ++++++++++++++++++++++++++++++++++++++
>  tests/xfs/776.out |    5 +++
>  4 files changed, 147 insertions(+)
>  create mode 100755 tests/xfs/774
>  create mode 100644 tests/xfs/774.out
>  create mode 100755 tests/xfs/776
>  create mode 100644 tests/xfs/776.out
> 
> 
> diff --git a/tests/xfs/774 b/tests/xfs/774
> new file mode 100755
> index 00000000..4c6bc2c9
> --- /dev/null
> +++ b/tests/xfs/774
> @@ -0,0 +1,80 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2021 Oracle.  All Rights Reserved.
> +#
> +# FS QA Test 774
> +#
> +# Regression test for kernel commits:
> +#
> +# 6b69e485894b ("xfs: standardize extent size hint validation")
> +# 603f000b15f2 ("xfs: validate extsz hints against rt extent size when rtinherit is set")
> +#
> +# Regression test for xfsprogs commit:
> +#
> +# 1e8afffb ("mkfs: validate rt extent size hint when rtinherit is set")
> +#
> +# Collectively, these patches ensure that we cannot set the extent size hint on
> +# a directory when the directory is configured to propagate its realtime and
> +# extent size hint to newly created files when the hint size isn't aligned to
> +# the size of a realtime extent.  If the patches aren't applied, the write will
> +# fail and xfs_repair will say that the fs is corrupt.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick realtime

Also add 'mkfs' group? Or we could split the mkfs test into a new test?

> +
> +# Import common functions.
> +. ./common/filter
> +
> +# real QA test starts here
> +_supported_fs generic

_supported_fs xfs

> +_require_realtime
> +_require_scratch
> +
> +# Check mkfs.xfs option parsing with regards to rtinherit.  XFS doesn't require
> +# the realtime volume to be present to set rtinherit, so it's safe to call the
> +# mkfs binary directly, in dry run mode, with exactly the parameters we want to
> +# check.
> +mkfs_args=(-f -N -r extsize=7b -d extszinherit=15 $SCRATCH_DEV)
> +$MKFS_XFS_PROG -d rtinherit=1 "${mkfs_args[@]}" &>> $seqres.full && \
> +	echo "mkfs should not succeed with heritable rtext-unaligned extent hint"
> +$MKFS_XFS_PROG -d rtinherit=0 "${mkfs_args[@]}" &>> $seqres.full || \
> +	echo "mkfs should succeed with uninheritable rtext-unaligned extent hint"
> +
> +# Move on to checking the kernel's behavior
> +_scratch_mkfs -r extsize=7b | _filter_mkfs >> $seqres.full 2> $tmp.mkfs
> +cat $tmp.mkfs >> $seqres.full
> +. $tmp.mkfs
> +_scratch_mount
> +
> +test $rtextsz -ne $dbsize || _notrun "failed to set large rt extent size"

This message looks like a failure. Print which condition is not met?

> +
> +# Ensure there's no extent size hint set on the directory, then set the
> +# rtinherit bit on the directory to test propagation.
> +$XFS_IO_PROG -c 'extsize 0' -c 'chattr +t' $SCRATCH_MNT
> +
> +# Now try to set an extent size hint on the directory that isn't aligned to
> +# the rt extent size.
> +$XFS_IO_PROG -c "extsize $((rtextsz + dbsize))" $SCRATCH_MNT 2>&1 | _filter_scratch
> +$XFS_IO_PROG -c 'stat -v' $SCRATCH_MNT > $tmp.stat
> +cat $tmp.stat >> $seqres.full
> +grep -q 'fsxattr.xflags.*rt-inherit' $tmp.stat || \
> +	echo "rtinherit didn't get set on the directory?"
> +grep 'fsxattr.extsize' $tmp.stat
> +
> +# Propagate the hint from directory to file
> +echo moo > $SCRATCH_MNT/dummy
> +$XFS_IO_PROG -c 'stat -v' $SCRATCH_MNT/dummy > $tmp.stat
> +cat $tmp.stat >> $seqres.full
> +grep -q 'fsxattr.xflags.*realtime' $tmp.stat || \
> +	echo "realtime didnt' get set on the file?"
> +grep 'fsxattr.extsize' $tmp.stat
> +
> +# Cycle the mount to force the inode verifier to run.
> +_scratch_cycle_mount
> +
> +# Can we still access the dummy file?
> +cat $SCRATCH_MNT/dummy
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/xfs/774.out b/tests/xfs/774.out
> new file mode 100644
> index 00000000..767a504e
> --- /dev/null
> +++ b/tests/xfs/774.out
> @@ -0,0 +1,5 @@
> +QA output created by 774
> +xfs_io: FS_IOC_FSSETXATTR SCRATCH_MNT: Invalid argument
> +fsxattr.extsize = 0
> +fsxattr.extsize = 0
> +moo
> diff --git a/tests/xfs/776 b/tests/xfs/776
> new file mode 100755
> index 00000000..a62da9a5
> --- /dev/null
> +++ b/tests/xfs/776
> @@ -0,0 +1,57 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (c) 2021, Oracle.  All Rights Reserved.
> +#
> +# FS QA Test No. 776
> +#
> +# Functional test for xfsprogs commit:
> +#
> +# 5f062427 ("xfs_repair: validate alignment of inherited rt extent hints")
> +#
> +# This xfs_repair patch detects directories that are configured to propagate
> +# their realtime and extent size hints to newly created realtime files when the
> +# hint size isn't aligned to the size of a realtime extent.
> +#
> +# Since this is a test of userspace tool functionality, we don't need kernel
> +# support, which in turn means that we omit _require_realtime.  Note that XFS
> +# allows users to configure realtime extent size geometry and set RTINHERIT
> +# flags even if the filesystem itself does not have a realtime volume attached.
> +#
> +. ./common/preamble
> +_begin_fstest auto repair fuzzers
> +
> +# Import common functions.
> +. ./common/filter
> +
> +# real QA test starts here

_supported_fs xfs

> +_require_scratch
> +
> +echo "Format and mount"
> +_scratch_mkfs -r extsize=7b | _filter_mkfs > $seqres.full 2>$tmp.mkfs
> +cat $tmp.mkfs >> $seqres.full
> +. $tmp.mkfs
> +
> +test $rtextsz -ne $dbsize || _notrun "failed to set large rt extent size"

Same here.

Thanks,
Eryu

> +
> +_scratch_mount >> $seqres.full 2>&1
> +rootino=$(stat -c '%i' $SCRATCH_MNT)
> +_scratch_unmount
> +
> +echo "Misconfigure the root directory"
> +rtextsz_blks=$((rtextsz / dbsize))
> +_scratch_xfs_db -x -c "inode $rootino" \
> +	-c "write -d core.extsize $((rtextsz_blks + 1))" \
> +	-c 'write -d core.rtinherit 1' \
> +	-c 'write -d core.extszinherit 1' \
> +	-c 'print' >> $seqres.full
> +
> +echo "Detect misconfigured directory"
> +_scratch_xfs_repair -n >> $seqres.full 2>&1 && \
> +	echo "repair did not catch error?"
> +
> +echo "Repair misconfigured directory"
> +_scratch_xfs_repair >> $seqres.full 2>&1 || \
> +	echo "repair did not fix error?"
> +
> +status=0
> +exit
> diff --git a/tests/xfs/776.out b/tests/xfs/776.out
> new file mode 100644
> index 00000000..05ea73b2
> --- /dev/null
> +++ b/tests/xfs/776.out
> @@ -0,0 +1,5 @@
> +QA output created by 776
> +Format and mount
> +Misconfigure the root directory
> +Detect misconfigured directory
> +Repair misconfigured directory

Darrick J. Wong Sept. 13, 2021, 5:57 p.m. UTC | #2

On Sun, Sep 05, 2021 at 10:35:57PM +0800, Eryu Guan wrote:
> On Tue, Aug 31, 2021 at 05:11:35PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <[e-mail]>
> > 
> > This is a regression test for the following fixes:
> > 
> >  xfs: standardize extent size hint validation
> >  xfs: validate extsz hints against rt extent size when rtinherit is set
> >  mkfs: validate rt extent size hint when rtinherit is set
> > 
> > These patches fix inadequate rtextsize alignment validation of extent
> > size hints on directories with the rtinherit and extszinherit flags set.
> > 
> > Signed-off-by: Darrick J. Wong <[e-mail]>
> > ---
> >  tests/xfs/774     |   80 +++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  tests/xfs/774.out |    5 +++
> >  tests/xfs/776     |   57 ++++++++++++++++++++++++++++++++++++++
> >  tests/xfs/776.out |    5 +++
> >  4 files changed, 147 insertions(+)
> >  create mode 100755 tests/xfs/774
> >  create mode 100644 tests/xfs/774.out
> >  create mode 100755 tests/xfs/776
> >  create mode 100644 tests/xfs/776.out
> > 
> > 
> > diff --git a/tests/xfs/774 b/tests/xfs/774
> > new file mode 100755
> > index 00000000..4c6bc2c9
> > --- /dev/null
> > +++ b/tests/xfs/774
> > @@ -0,0 +1,80 @@
> > +#! /bin/bash
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Copyright (c) 2021 Oracle.  All Rights Reserved.
> > +#
> > +# FS QA Test 774
> > +#
> > +# Regression test for kernel commits:
> > +#
> > +# 6b69e485894b ("xfs: standardize extent size hint validation")
> > +# 603f000b15f2 ("xfs: validate extsz hints against rt extent size when rtinherit is set")
> > +#
> > +# Regression test for xfsprogs commit:
> > +#
> > +# 1e8afffb ("mkfs: validate rt extent size hint when rtinherit is set")
> > +#
> > +# Collectively, these patches ensure that we cannot set the extent size hint on
> > +# a directory when the directory is configured to propagate its realtime and
> > +# extent size hint to newly created files when the hint size isn't aligned to
> > +# the size of a realtime extent.  If the patches aren't applied, the write will
> > +# fail and xfs_repair will say that the fs is corrupt.
> > +#
> > +. ./common/preamble
> > +_begin_fstest auto quick realtime
> 
> Also add 'mkfs' group?

I'll add it to the group list.

> Or we could split the mkfs test into a new test?

I could, but...

> > +
> > +# Import common functions.
> > +. ./common/filter
> > +
> > +# real QA test starts here
> > +_supported_fs generic
> 
> _supported_fs xfs
> 
> > +_require_realtime
> > +_require_scratch
> > +
> > +# Check mkfs.xfs option parsing with regards to rtinherit.  XFS doesn't require
> > +# the realtime volume to be present to set rtinherit, so it's safe to call the
> > +# mkfs binary directly, in dry run mode, with exactly the parameters we want to
> > +# check.
> > +mkfs_args=(-f -N -r extsize=7b -d extszinherit=15 $SCRATCH_DEV)
> > +$MKFS_XFS_PROG -d rtinherit=1 "${mkfs_args[@]}" &>> $seqres.full && \
> > +	echo "mkfs should not succeed with heritable rtext-unaligned extent hint"
> > +$MKFS_XFS_PROG -d rtinherit=0 "${mkfs_args[@]}" &>> $seqres.full || \
> > +	echo "mkfs should succeed with uninheritable rtext-unaligned extent hint"

...these two lines are all that's needed to test the mkfs patch.  I've
simultaneoulsy gotten criticism in the past for (a) running up the
number of tests in the test suite (and hence increasing fstests runtime)
and (b) cramming too many small things into a test case, so I really
don't know where the dividing line is anymore.

Usually this means I cram everything into as few tests as possible,
except for tests that require out of band updates to ondisk metadata
(e.g. fuzzers), tests that can crash the kernel, or anything else that
doesn't "feel" like it fits the usual test behavior ... and then split
things on demand.

That was a longwinded way to say that I'll split the mkfs part into a
two-line test if you insist.

> > +
> > +# Move on to checking the kernel's behavior
> > +_scratch_mkfs -r extsize=7b | _filter_mkfs >> $seqres.full 2> $tmp.mkfs
> > +cat $tmp.mkfs >> $seqres.full
> > +. $tmp.mkfs
> > +_scratch_mount
> > +
> > +test $rtextsz -ne $dbsize || _notrun "failed to set large rt extent size"
> 
> This message looks like a failure. Print which condition is not met?

Ok, I'll change it to:

_notrun "cannot set rt extent size ($rtextsz) larger than fs block size ($dbsize)"

> > +
> > +# Ensure there's no extent size hint set on the directory, then set the
> > +# rtinherit bit on the directory to test propagation.
> > +$XFS_IO_PROG -c 'extsize 0' -c 'chattr +t' $SCRATCH_MNT
> > +
> > +# Now try to set an extent size hint on the directory that isn't aligned to
> > +# the rt extent size.
> > +$XFS_IO_PROG -c "extsize $((rtextsz + dbsize))" $SCRATCH_MNT 2>&1 | _filter_scratch
> > +$XFS_IO_PROG -c 'stat -v' $SCRATCH_MNT > $tmp.stat
> > +cat $tmp.stat >> $seqres.full
> > +grep -q 'fsxattr.xflags.*rt-inherit' $tmp.stat || \
> > +	echo "rtinherit didn't get set on the directory?"
> > +grep 'fsxattr.extsize' $tmp.stat
> > +
> > +# Propagate the hint from directory to file
> > +echo moo > $SCRATCH_MNT/dummy
> > +$XFS_IO_PROG -c 'stat -v' $SCRATCH_MNT/dummy > $tmp.stat
> > +cat $tmp.stat >> $seqres.full
> > +grep -q 'fsxattr.xflags.*realtime' $tmp.stat || \
> > +	echo "realtime didnt' get set on the file?"
> > +grep 'fsxattr.extsize' $tmp.stat
> > +
> > +# Cycle the mount to force the inode verifier to run.
> > +_scratch_cycle_mount
> > +
> > +# Can we still access the dummy file?
> > +cat $SCRATCH_MNT/dummy
> > +
> > +# success, all done
> > +status=0
> > +exit
> > diff --git a/tests/xfs/774.out b/tests/xfs/774.out
> > new file mode 100644
> > index 00000000..767a504e
> > --- /dev/null
> > +++ b/tests/xfs/774.out
> > @@ -0,0 +1,5 @@
> > +QA output created by 774
> > +xfs_io: FS_IOC_FSSETXATTR SCRATCH_MNT: Invalid argument
> > +fsxattr.extsize = 0
> > +fsxattr.extsize = 0
> > +moo
> > diff --git a/tests/xfs/776 b/tests/xfs/776
> > new file mode 100755
> > index 00000000..a62da9a5
> > --- /dev/null
> > +++ b/tests/xfs/776
> > @@ -0,0 +1,57 @@
> > +#! /bin/bash
> > +# SPDX-License-Identifier: GPL-2.0
> > +# Copyright (c) 2021, Oracle.  All Rights Reserved.
> > +#
> > +# FS QA Test No. 776
> > +#
> > +# Functional test for xfsprogs commit:
> > +#
> > +# 5f062427 ("xfs_repair: validate alignment of inherited rt extent hints")
> > +#
> > +# This xfs_repair patch detects directories that are configured to propagate
> > +# their realtime and extent size hints to newly created realtime files when the
> > +# hint size isn't aligned to the size of a realtime extent.
> > +#
> > +# Since this is a test of userspace tool functionality, we don't need kernel
> > +# support, which in turn means that we omit _require_realtime.  Note that XFS
> > +# allows users to configure realtime extent size geometry and set RTINHERIT
> > +# flags even if the filesystem itself does not have a realtime volume attached.
> > +#
> > +. ./common/preamble
> > +_begin_fstest auto repair fuzzers
> > +
> > +# Import common functions.
> > +. ./common/filter
> > +
> > +# real QA test starts here
> 
> _supported_fs xfs
> 
> > +_require_scratch
> > +
> > +echo "Format and mount"
> > +_scratch_mkfs -r extsize=7b | _filter_mkfs > $seqres.full 2>$tmp.mkfs
> > +cat $tmp.mkfs >> $seqres.full
> > +. $tmp.mkfs
> > +
> > +test $rtextsz -ne $dbsize || _notrun "failed to set large rt extent size"
> 
> Same here.

Ok, fixed.  Sorry that a lot of my tests seem to omit _supported_fs;
I'll go check the rest of my tree before I resubmit.

--D

> Thanks,
> Eryu
> 
> > +
> > +_scratch_mount >> $seqres.full 2>&1
> > +rootino=$(stat -c '%i' $SCRATCH_MNT)
> > +_scratch_unmount
> > +
> > +echo "Misconfigure the root directory"
> > +rtextsz_blks=$((rtextsz / dbsize))
> > +_scratch_xfs_db -x -c "inode $rootino" \
> > +	-c "write -d core.extsize $((rtextsz_blks + 1))" \
> > +	-c 'write -d core.rtinherit 1' \
> > +	-c 'write -d core.extszinherit 1' \
> > +	-c 'print' >> $seqres.full
> > +
> > +echo "Detect misconfigured directory"
> > +_scratch_xfs_repair -n >> $seqres.full 2>&1 && \
> > +	echo "repair did not catch error?"
> > +
> > +echo "Repair misconfigured directory"
> > +_scratch_xfs_repair >> $seqres.full 2>&1 || \
> > +	echo "repair did not fix error?"
> > +
> > +status=0
> > +exit
> > diff --git a/tests/xfs/776.out b/tests/xfs/776.out
> > new file mode 100644
> > index 00000000..05ea73b2
> > --- /dev/null
> > +++ b/tests/xfs/776.out
> > @@ -0,0 +1,5 @@
> > +QA output created by 776
> > +Format and mount
> > +Misconfigure the root directory
> > +Detect misconfigured directory
> > +Repair misconfigured directory

Patch

diff --git a/tests/xfs/774 b/tests/xfs/774
new file mode 100755
index 00000000..4c6bc2c9
--- /dev/null
+++ b/tests/xfs/774
@@ -0,0 +1,80 @@ 
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2021 Oracle.  All Rights Reserved.
+#
+# FS QA Test 774
+#
+# Regression test for kernel commits:
+#
+# 6b69e485894b ("xfs: standardize extent size hint validation")
+# 603f000b15f2 ("xfs: validate extsz hints against rt extent size when rtinherit is set")
+#
+# Regression test for xfsprogs commit:
+#
+# 1e8afffb ("mkfs: validate rt extent size hint when rtinherit is set")
+#
+# Collectively, these patches ensure that we cannot set the extent size hint on
+# a directory when the directory is configured to propagate its realtime and
+# extent size hint to newly created files when the hint size isn't aligned to
+# the size of a realtime extent.  If the patches aren't applied, the write will
+# fail and xfs_repair will say that the fs is corrupt.
+#
+. ./common/preamble
+_begin_fstest auto quick realtime
+
+# Import common functions.
+. ./common/filter
+
+# real QA test starts here
+_supported_fs generic
+_require_realtime
+_require_scratch
+
+# Check mkfs.xfs option parsing with regards to rtinherit.  XFS doesn't require
+# the realtime volume to be present to set rtinherit, so it's safe to call the
+# mkfs binary directly, in dry run mode, with exactly the parameters we want to
+# check.
+mkfs_args=(-f -N -r extsize=7b -d extszinherit=15 $SCRATCH_DEV)
+$MKFS_XFS_PROG -d rtinherit=1 "${mkfs_args[@]}" &>> $seqres.full && \
+	echo "mkfs should not succeed with heritable rtext-unaligned extent hint"
+$MKFS_XFS_PROG -d rtinherit=0 "${mkfs_args[@]}" &>> $seqres.full || \
+	echo "mkfs should succeed with uninheritable rtext-unaligned extent hint"
+
+# Move on to checking the kernel's behavior
+_scratch_mkfs -r extsize=7b | _filter_mkfs >> $seqres.full 2> $tmp.mkfs
+cat $tmp.mkfs >> $seqres.full
+. $tmp.mkfs
+_scratch_mount
+
+test $rtextsz -ne $dbsize || _notrun "failed to set large rt extent size"
+
+# Ensure there's no extent size hint set on the directory, then set the
+# rtinherit bit on the directory to test propagation.
+$XFS_IO_PROG -c 'extsize 0' -c 'chattr +t' $SCRATCH_MNT
+
+# Now try to set an extent size hint on the directory that isn't aligned to
+# the rt extent size.
+$XFS_IO_PROG -c "extsize $((rtextsz + dbsize))" $SCRATCH_MNT 2>&1 | _filter_scratch
+$XFS_IO_PROG -c 'stat -v' $SCRATCH_MNT > $tmp.stat
+cat $tmp.stat >> $seqres.full
+grep -q 'fsxattr.xflags.*rt-inherit' $tmp.stat || \
+	echo "rtinherit didn't get set on the directory?"
+grep 'fsxattr.extsize' $tmp.stat
+
+# Propagate the hint from directory to file
+echo moo > $SCRATCH_MNT/dummy
+$XFS_IO_PROG -c 'stat -v' $SCRATCH_MNT/dummy > $tmp.stat
+cat $tmp.stat >> $seqres.full
+grep -q 'fsxattr.xflags.*realtime' $tmp.stat || \
+	echo "realtime didnt' get set on the file?"
+grep 'fsxattr.extsize' $tmp.stat
+
+# Cycle the mount to force the inode verifier to run.
+_scratch_cycle_mount
+
+# Can we still access the dummy file?
+cat $SCRATCH_MNT/dummy
+
+# success, all done
+status=0
+exit
diff --git a/tests/xfs/774.out b/tests/xfs/774.out
new file mode 100644
index 00000000..767a504e
--- /dev/null
+++ b/tests/xfs/774.out
@@ -0,0 +1,5 @@ 
+QA output created by 774
+xfs_io: FS_IOC_FSSETXATTR SCRATCH_MNT: Invalid argument
+fsxattr.extsize = 0
+fsxattr.extsize = 0
+moo
diff --git a/tests/xfs/776 b/tests/xfs/776
new file mode 100755
index 00000000..a62da9a5
--- /dev/null
+++ b/tests/xfs/776
@@ -0,0 +1,57 @@ 
+#! /bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (c) 2021, Oracle.  All Rights Reserved.
+#
+# FS QA Test No. 776
+#
+# Functional test for xfsprogs commit:
+#
+# 5f062427 ("xfs_repair: validate alignment of inherited rt extent hints")
+#
+# This xfs_repair patch detects directories that are configured to propagate
+# their realtime and extent size hints to newly created realtime files when the
+# hint size isn't aligned to the size of a realtime extent.
+#
+# Since this is a test of userspace tool functionality, we don't need kernel
+# support, which in turn means that we omit _require_realtime.  Note that XFS
+# allows users to configure realtime extent size geometry and set RTINHERIT
+# flags even if the filesystem itself does not have a realtime volume attached.
+#
+. ./common/preamble
+_begin_fstest auto repair fuzzers
+
+# Import common functions.
+. ./common/filter
+
+# real QA test starts here
+_require_scratch
+
+echo "Format and mount"
+_scratch_mkfs -r extsize=7b | _filter_mkfs > $seqres.full 2>$tmp.mkfs
+cat $tmp.mkfs >> $seqres.full
+. $tmp.mkfs
+
+test $rtextsz -ne $dbsize || _notrun "failed to set large rt extent size"
+
+_scratch_mount >> $seqres.full 2>&1
+rootino=$(stat -c '%i' $SCRATCH_MNT)
+_scratch_unmount
+
+echo "Misconfigure the root directory"
+rtextsz_blks=$((rtextsz / dbsize))
+_scratch_xfs_db -x -c "inode $rootino" \
+	-c "write -d core.extsize $((rtextsz_blks + 1))" \
+	-c 'write -d core.rtinherit 1' \
+	-c 'write -d core.extszinherit 1' \
+	-c 'print' >> $seqres.full
+
+echo "Detect misconfigured directory"
+_scratch_xfs_repair -n >> $seqres.full 2>&1 && \
+	echo "repair did not catch error?"
+
+echo "Repair misconfigured directory"
+_scratch_xfs_repair >> $seqres.full 2>&1 || \
+	echo "repair did not fix error?"
+
+status=0
+exit
diff --git a/tests/xfs/776.out b/tests/xfs/776.out
new file mode 100644
index 00000000..05ea73b2
--- /dev/null
+++ b/tests/xfs/776.out
@@ -0,0 +1,5 @@ 
+QA output created by 776
+Format and mount
+Misconfigure the root directory
+Detect misconfigured directory
+Repair misconfigured directory