diff mbox

common: add support for the "local" file system type

Message ID 20180503034340.GA20908@thunk.org (mailing list archive)
State New, archived
Headers show

Commit Message

Theodore Ts'o May 3, 2018, 3:43 a.m. UTC
About a year and half ago, I sent the patch attached below to add
support for a "local" file system type where the file system could not
be mounted or dismounted, but where writes to TEST_DIR and SCRATCH_MNT
would be testing the file system in question.  At the time, I couldn't
describe the use case in any greater detail than what I had in the
commit description, and Dave Chinner at the time rejected the patch
since he didn't like xfstests being used to test a proprietary file
system for which I was not able to explain the details of what we were
trying to do.

Not a big deal, I just kept the patch in my private fork[1] of
xfstests on github.

[1] https://github.com/tytso/xfstests

However, happily, we can now talk a lot more about what the "local"
file system type in xfstests was used to test.  Earlier today, Google
announced gVisor[2], and published it as open source on github[3].
gVisor works much like User Mode Linux, and I suspect much like the
Windows Subsystem for Linux in that it uses the x86_64's hardware
virtualization extensions (so it has the security fencing much like a
VM) but instead of emulating hardware, instead the emulation layer is
done at the system call level (so it's more efficient than a VM, since
there is no guest kernel).

[2] https://cloudplatform.googleblog.com/2018/05/Open-sourcing-gVisor-a-sandboxed-container-runtime.html
[3] https://github.com/google/gvisor

File systems can be implemented using Gophers[4] in a separate
process, where the communication between the gVisor sandbox and the
Gopher is via the 9P2000.L protocol.  This means that if you want to
try to exploit a buffer overflow in the userspace file system, first
you have to get past the system call validation checks done by the
gVisor Sentry process (which is written in Go which makes this rather
more difficult, especially since the Sentry process itself is
protected using seccomp[5]).  Then the buffer overflow attack has to
make it past the 9P protocol encoding/decoding, and then survive the
9P protocol validation checks in the Gopher.  The Gopher process
provides an emulated file system service using the Cloud Provider's
internal cluster storage services, much like in GCE, the Persistent
Disk service provides an emulated block device service.

[4] https://news.ycombinator.com/item?id=16979126
[5] https://news.ycombinator.com/item?id=16976557

This whole system was designed with security first and foremost.  Of
course, we also want it to pass the file system checks, which is why
were using xfstests.

The way we actually tested the gVisor file system was via a Docker
container (the Dockerfile[6] is in the xfstests-bld git repo) which
would then get consumed by gVisor's Docker/Kubernetes integration
layer.

[6] https://github.com/tytso/xfstests-bld/blob/master/Dockerfile

Anyway, back in September, 2016, Dave Chinner was peeved that I
couldn't give this full description, and I'm glad to say, now we can
finally rectify that gap.  :-)

Could this commit therefore please be considered for inclusion in
xfstests upstream?

Many thanks!

						- Ted


From 8b40b28866dca119d0c807c31ae48f153ec2dc53 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Sat, 17 Sep 2016 19:08:18 -0400
Subject: [PATCH] common: add support for the "local" file system type

It is sometimes useful to be able to test the local file system
provided in a restricted execution environment (such as that which is
provided by Docker, for example) where it is not possible to mount and
unmount the file system under test.

To support this test case, add support for a new file system type
called "local".  The TEST_DEV and SCRATCH_DEV should be have a
non-block device format (e.g., local:/test or local:/scratch), and the
TEST_DIR and SCRATCH_MNT directories should be pre-existing
directories provided by the execution environment.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---
 common/rc | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 70 insertions(+), 3 deletions(-)

Comments

Amir Goldstein May 3, 2018, 9:22 a.m. UTC | #1
On Thu, May 3, 2018 at 6:43 AM, Theodore Y. Ts'o <tytso@mit.edu> wrote:
[...]
> From 8b40b28866dca119d0c807c31ae48f153ec2dc53 Mon Sep 17 00:00:00 2001
> From: Theodore Ts'o <tytso@mit.edu>
> Date: Sat, 17 Sep 2016 19:08:18 -0400
> Subject: [PATCH] common: add support for the "local" file system type
>
> It is sometimes useful to be able to test the local file system
> provided in a restricted execution environment (such as that which is
> provided by Docker, for example) where it is not possible to mount and
> unmount the file system under test.
>
> To support this test case, add support for a new file system type
> called "local".  The TEST_DEV and SCRATCH_DEV should be have a
> non-block device format (e.g., local:/test or local:/scratch), and the
> TEST_DIR and SCRATCH_MNT directories should be pre-existing
> directories provided by the execution environment.

Ted,

This looks like a very useful feature, but I suspect that some bits of the
patch may be a bit too specific to your use case (see below) - I may be wrong.
I bet there is a large variety of out of tree xfstests patches named
"Add support for XXX fs" that could be avoided with this feature.

The ultimate proof would be to demonstrate the usefulness of the feature
to more than a single use case - how about FUSE passthrough example?
Perhaps FSTYP=user would be more descriptive in general to the use
case at hand, because 'local' is usually the counter of 'remote',
but I'm fine with FSTYP=local.

Another way to "market" the feature is FSTYP=generic, which is the
prototype of all other filesystems. Naturally, it only runs tests under
tests/generic (as FSTYP=local does) and any test that requires an
operation that has no generic implementation is notrun.


>
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> ---
>  common/rc | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 70 insertions(+), 3 deletions(-)
>
> diff --git a/common/rc b/common/rc
> index 9ffab7fd..d5cb0fe4 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -351,6 +351,18 @@ _supports_filetype()
>         esac
>  }
>
> +_local_validate_mount_opt()
> +{
> +    case "$*" in
> +       ro|ro,*|*,ro) _notrun "ro mount option not supported" ;;
> +       *nosuid*) _notrun "nosuid mount option not supported" ;;
> +       *noatime*) _notrun "noatime mount option not supported" ;;
> +       *relatime*) _notrun "relatime mount option not supported" ;;
> +       *diratime*) _notrun "diratime mount option not supported" ;;
> +       *strictatime*) _notrun "strictatime mount option not supported" ;;
> +    esac
> +}

Why specifically these mount options? Is this really generic?

> +
>  # mount scratch device with given options but don't check mount status
>  _try_scratch_mount()
>  {
> @@ -376,6 +388,9 @@ _scratch_unmount()
>         btrfs)
>                 $UMOUNT_PROG $SCRATCH_MNT
>                 ;;
> +       local)
> +                rm -rf $SCRATCH_MNT/*
> +                ;;

_scratch_mkfs already does that. Why does it make sense in _scratch_unmount?

>         *)
>                 $UMOUNT_PROG $SCRATCH_DEV
>                 ;;
> @@ -386,6 +401,10 @@ _scratch_remount()
>  {
>      local opts="$1"
>
> +    if [ "$FSTYP" = "local" ]; then
> +       _local_validate_mount_opt "$*"
> +       return 0;
> +    fi

It makes more sense to me to _require_scratch_remount
for tests that need to remount in the beginning of tests - yeh
that's a bit more work.

>      if test -n "$opts"; then
>         mount -o "remount,$opts" $SCRATCH_MNT
>      fi
> @@ -395,7 +414,7 @@ _scratch_cycle_mount()
>  {
>      local opts="$1"
>
> -    if [ "$FSTYP" = tmpfs ]; then
> +    if [ "$FSTYP" = "tmpfs" -o "$FSTYP" = "local" ] ; then
>         _scratch_remount "$opts"

That seems like cheating - seems better to implement
and use _require_scratch_cycle_mount

>         return
>      fi
> @@ -429,6 +448,10 @@ _test_mount()
>          _overlay_test_mount $*
>          return $?
>      fi
> +    if [ "$FSTYP" == "local" ]; then
> +        mkdir -p $TEST_DIR
> +       return $?
> +    fi

What is the desired logic here? can you add a comment?
Seems to me that we need to verify there is something mounted
at $TEST_DIR. no?

>      _test_options mount
>      _mount -t $FSTYP $TEST_OPTIONS $TEST_FS_MOUNT_OPTS $SELINUX_MOUNT_OPTIONS $* $TEST_DEV $TEST_DIR
>  }
> @@ -437,7 +460,7 @@ _test_unmount()
>  {
>         if [ "$FSTYP" == "overlay" ]; then
>                 _overlay_test_unmount
> -       else
> +       elif [ "$FSTYP" != "local" ]; then
>                 $UMOUNT_PROG $TEST_DEV
>         fi
>  }
> @@ -723,7 +746,7 @@ _scratch_mkfs()
>         local mkfs_status
>
>         case $FSTYP in
> -       nfs*|cifs|ceph|overlay|glusterfs|pvfs2|9p)
> +       nfs*|cifs|ceph|overlay|glusterfs|pvfs2|9p|local)
>                 # unable to re-create this fstyp, just remove all files in
>                 # $SCRATCH_MNT to avoid EEXIST caused by the leftover files
>                 # created in previous runs
> @@ -1465,6 +1488,10 @@ _check_mounted_on()
>         local mnt=$4
>         local type=$5
>
> +       if [ "$FSTYP" == "local" ]; then
> +               return 0
> +       fi
> +

Shouldn't we check that "something" is mounted on $mnt?

>         # find $dev as the source, and print result in "$dev $mnt" format
>         local mount_rec=`findmnt -rncv -S $dev -o SOURCE,TARGET`
>         [ -n "$mount_rec" ] || return 1 # 1 = not mounted
> @@ -1562,6 +1589,13 @@ _require_scratch_nocheck()
>                         _notrun "this test requires a valid \$SCRATCH_MNT"
>                 fi
>                 ;;
> +       local)
> +               if [ -z "$SCRATCH_DEV" -o ! -d "$SCRATCH_MNT" ];
> +               then
> +                   _notrun "this test requires a valid \$SCRATCH_MNT and unique $SCRATCH_DEV"
> +               fi
> +               return 0
> +               ;;
>         *)
>                  if [ -z "$SCRATCH_DEV" -o "`_is_block_dev "$SCRATCH_DEV"`" = "" ]
>                  then
> @@ -1683,6 +1717,13 @@ _require_test()
>                         _notrun "this test requires a valid \$TEST_DIR"
>                 fi
>                 ;;
> +       local)
> +               if [ -z "$TEST_DEV" -o ! -d "$TEST_DIR" ];
> +               then
> +                   _notrun "this test requires a valid \$TEST_DIR and unique $TEST_DEV"
> +               fi
> +               return 0
> +               ;;
>         *)
>                  if [ -z "$TEST_DEV" ] || [ "`_is_block_dev "$TEST_DEV"`" = "" ]
>                  then
> @@ -2438,6 +2479,10 @@ _remount()
>      local device=$1
>      local mode=$2
>
> +    if [ "$FSTYP" == "local" ] ; then
> +       return 0
> +    fi
> +
>      if ! mount -o remount,$mode $device
>      then
>          echo "_remount: failed to remount filesystem on $device as $mode"
> @@ -2483,6 +2528,10 @@ _mount_or_remount_rw()
>         local device=$2
>         local mountpoint=$3
>
> +       if [ "$FSTYP" == "local" ] ; then
> +           return 0
> +       fi
> +
>         if [ $USE_REMOUNT -eq 0 ]; then
>                 if [ "$FSTYP" != "overlay" ]; then
>                         _mount -t $FSTYP $mount_opts $device $mountpoint
> @@ -2636,6 +2685,9 @@ _check_test_fs()
>      ubifs)
>         # there is no fsck program for ubifs yet
>         ;;
> +    local)
> +       # no way to check consistency for local
> +       ;;
>      *)
>         _check_generic_filesystem $TEST_DEV
>         ;;
> @@ -2691,6 +2743,9 @@ _check_scratch_fs()
>      ubifs)
>         # there is no fsck program for ubifs yet
>         ;;
> +    local)
> +       # no way to check consistency for local
> +       ;;
>      *)
>         _check_generic_filesystem $device
>         ;;
> @@ -3003,6 +3058,9 @@ _require_fio()
>  # Does freeze work on this fs?
>  _require_freeze()
>  {
> +       if [ "$FSTYP" == "local" ]; then
> +               _notrun "local does not support freeze"

When users read this warning they may be confused,
same for shutdown/dax/morecovery.
Something like "user defined fs does not support freeze"

Thanks,
Amir.
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Theodore Ts'o May 3, 2018, 6:35 p.m. UTC | #2
On Thu, May 03, 2018 at 12:22:42PM +0300, Amir Goldstein wrote:
> 
> This looks like a very useful feature, but I suspect that some bits of the
> patch may be a bit too specific to your use case (see below) - I may be wrong.

The primary characteristic of "local" is there nothing to mount or
unmount.  So for example, it should be possible to use this
Microsoft's Subsystem for Linux.

> The ultimate proof would be to demonstrate the usefulness of the feature
> to more than a single use case - how about FUSE passthrough example?
> Perhaps FSTYP=user would be more descriptive in general to the use
> case at hand, because 'local' is usually the counter of 'remote',
> but I'm fine with FSTYP=local.

It certainly wouldn't be problem to demo using the local file system
type for FUSE --- but it would not be _ideal_ for fuse, since fuse has
the concept of mounting and unmounting.

> > +{
> > +    case "$*" in
> > +       ro|ro,*|*,ro) _notrun "ro mount option not supported" ;;
> > +       *nosuid*) _notrun "nosuid mount option not supported" ;;
> > +       *noatime*) _notrun "noatime mount option not supported" ;;
> > +       *relatime*) _notrun "relatime mount option not supported" ;;
> > +       *diratime*) _notrun "diratime mount option not supported" ;;
> > +       *strictatime*) _notrun "strictatime mount option not supported" ;;
> > +    esac
> > +}
> 
> Why specifically these mount options? Is this really generic?

The local file system type does not support mount, umount, or remount
command.  So there is no way to modulate noatime, relatime, etc.  So
this would be useful if someone wanted to test Windows System for
Linux, for example.

> > +
> >  # mount scratch device with given options but don't check mount status
> >  _try_scratch_mount()
> >  {
> > @@ -376,6 +388,9 @@ _scratch_unmount()
> >         btrfs)
> >                 $UMOUNT_PROG $SCRATCH_MNT
> >                 ;;
> > +       local)
> > +                rm -rf $SCRATCH_MNT/*
> > +                ;;
> 
> _scratch_mkfs already does that. Why does it make sense in _scratch_unmount?

Just for cleanup purposes.

> > @@ -386,6 +401,10 @@ _scratch_remount()
> >  {
> >      local opts="$1"
> >
> > +    if [ "$FSTYP" = "local" ]; then
> > +       _local_validate_mount_opt "$*"
> > +       return 0;
> > +    fi
> 
> It makes more sense to me to _require_scratch_remount
> for tests that need to remount in the beginning of tests - yeh
> that's a bit more work.

There are some tests where the remount operation is just to reset the
file system.  So the test is just to unmount and remount the file
system, and making sure the file status are the same.  So I didn't
want to block all remounts; instead, to let some remounts be no-op's
so the rest of the test could still be used to provide test coverage,
and only block those remounts which were modulating things like ro/rw,
noatime, etc.

> > @@ -395,7 +414,7 @@ _scratch_cycle_mount()
> >  {
> >      local opts="$1"
> >
> > -    if [ "$FSTYP" = tmpfs ]; then
> > +    if [ "$FSTYP" = "tmpfs" -o "$FSTYP" = "local" ] ; then
> >         _scratch_remount "$opts"
> 
> That seems like cheating - seems better to implement
> and use _require_scratch_cycle_mount

Again, I didn't want to end up skipping a huge number of tests.  I
didn't consider this "cheating"; I considered it a case of "let's
maximize test coverage".

> > +    if [ "$FSTYP" == "local" ]; then
> > +        mkdir -p $TEST_DIR
> > +       return $?
> > +    fi
> 
> What is the desired logic here? can you add a comment?
> Seems to me that we need to verify there is something mounted
> at $TEST_DIR. no?

Again -- the big thing about the "local" file system is there is no
way to mount, umount, or remount.  So no block device, no mount point,
nothing to shutdown, etc.

The mkdir -p isn't strictly necessary here.  It could be done by the
kvm-xfstests or whatever is running the xfstests.  It was more of a
safety thing, but if people don't like it, we can drop it.

> > @@ -1465,6 +1488,10 @@ _check_mounted_on()
> >         local mnt=$4
> >         local type=$5
> >
> > +       if [ "$FSTYP" == "local" ]; then
> > +               return 0
> > +       fi
> > +
> 
> Shouldn't we check that "something" is mounted on $mnt?

Nope.  See above.  "local" means never having to say you need to mount
something.

> > @@ -3003,6 +3058,9 @@ _require_fio()
> >  # Does freeze work on this fs?
> >  _require_freeze()
> >  {
> > +       if [ "$FSTYP" == "local" ]; then
> > +               _notrun "local does not support freeze"
> 
> When users read this warning they may be confused,
> same for shutdown/dax/morecovery.
> Something like "user defined fs does not support freeze"

I think you have a very different idea of what "local" means.  The
basic model was that this is something where the file system is
provided for use by the docker infrastructure (or by Windows 10 in the
WSL case), and so the docker job can't actually mount or unmount the
file system.  However, it is still desirable to check to see how POSIX
compliant the underlying file system might be, and it can also be used
to exercise the underlying file system.

I'm not tied to the name "local", but for me what it means is "the
local file system".  If people want to nominate a different name, I'm
certainly open to suggestions.

					- Ted

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Amir Goldstein May 3, 2018, 7:24 p.m. UTC | #3
On Thu, May 3, 2018 at 9:35 PM, Theodore Y. Ts'o <tytso@mit.edu> wrote:
> On Thu, May 03, 2018 at 12:22:42PM +0300, Amir Goldstein wrote:
>>
>> This looks like a very useful feature, but I suspect that some bits of the
>> patch may be a bit too specific to your use case (see below) - I may be wrong.
>
> The primary characteristic of "local" is there nothing to mount or
> unmount.  So for example, it should be possible to use this
> Microsoft's Subsystem for Linux.
>
>> The ultimate proof would be to demonstrate the usefulness of the feature
>> to more than a single use case - how about FUSE passthrough example?
>> Perhaps FSTYP=user would be more descriptive in general to the use
>> case at hand, because 'local' is usually the counter of 'remote',
>> but I'm fine with FSTYP=local.
>
> It certainly wouldn't be problem to demo using the local file system
> type for FUSE --- but it would not be _ideal_ for fuse, since fuse has
> the concept of mounting and unmounting.
>
>> > +{
>> > +    case "$*" in
>> > +       ro|ro,*|*,ro) _notrun "ro mount option not supported" ;;
>> > +       *nosuid*) _notrun "nosuid mount option not supported" ;;
>> > +       *noatime*) _notrun "noatime mount option not supported" ;;
>> > +       *relatime*) _notrun "relatime mount option not supported" ;;
>> > +       *diratime*) _notrun "diratime mount option not supported" ;;
>> > +       *strictatime*) _notrun "strictatime mount option not supported" ;;
>> > +    esac
>> > +}
>>
>> Why specifically these mount options? Is this really generic?
>
> The local file system type does not support mount, umount, or remount
> command.  So there is no way to modulate noatime, relatime, etc.  So
> this would be useful if someone wanted to test Windows System for
> Linux, for example.
>
>> > +
>> >  # mount scratch device with given options but don't check mount status
>> >  _try_scratch_mount()
>> >  {
>> > @@ -376,6 +388,9 @@ _scratch_unmount()
>> >         btrfs)
>> >                 $UMOUNT_PROG $SCRATCH_MNT
>> >                 ;;
>> > +       local)
>> > +                rm -rf $SCRATCH_MNT/*
>> > +                ;;
>>
>> _scratch_mkfs already does that. Why does it make sense in _scratch_unmount?
>
> Just for cleanup purposes.
>
>> > @@ -386,6 +401,10 @@ _scratch_remount()
>> >  {
>> >      local opts="$1"
>> >
>> > +    if [ "$FSTYP" = "local" ]; then
>> > +       _local_validate_mount_opt "$*"
>> > +       return 0;
>> > +    fi
>>
>> It makes more sense to me to _require_scratch_remount
>> for tests that need to remount in the beginning of tests - yeh
>> that's a bit more work.
>
> There are some tests where the remount operation is just to reset the
> file system.  So the test is just to unmount and remount the file
> system, and making sure the file status are the same.  So I didn't
> want to block all remounts; instead, to let some remounts be no-op's
> so the rest of the test could still be used to provide test coverage,
> and only block those remounts which were modulating things like ro/rw,
> noatime, etc.
>
>> > @@ -395,7 +414,7 @@ _scratch_cycle_mount()
>> >  {
>> >      local opts="$1"
>> >
>> > -    if [ "$FSTYP" = tmpfs ]; then
>> > +    if [ "$FSTYP" = "tmpfs" -o "$FSTYP" = "local" ] ; then
>> >         _scratch_remount "$opts"
>>
>> That seems like cheating - seems better to implement
>> and use _require_scratch_cycle_mount
>
> Again, I didn't want to end up skipping a huge number of tests.  I
> didn't consider this "cheating"; I considered it a case of "let's
> maximize test coverage".
>

OK. I've used _scratch_cycle_mount as well in exportfs tests
to make sure caches are evicted, so perhaps the "not cheating"
edition of _scratch_cycle_mount for local should at least drop
caches?

Thanks,
Amir.
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Eryu Guan May 6, 2018, 3:54 a.m. UTC | #4
On Wed, May 02, 2018 at 11:43:40PM -0400, Theodore Y. Ts'o wrote:
> About a year and half ago, I sent the patch attached below to add
> support for a "local" file system type where the file system could not
> be mounted or dismounted, but where writes to TEST_DIR and SCRATCH_MNT
> would be testing the file system in question.  At the time, I couldn't
> describe the use case in any greater detail than what I had in the
> commit description, and Dave Chinner at the time rejected the patch
> since he didn't like xfstests being used to test a proprietary file
> system for which I was not able to explain the details of what we were
> trying to do.
> 
> Not a big deal, I just kept the patch in my private fork[1] of
> xfstests on github.
> 
> [1] https://github.com/tytso/xfstests
> 
> However, happily, we can now talk a lot more about what the "local"
> file system type in xfstests was used to test.  Earlier today, Google
> announced gVisor[2], and published it as open source on github[3].
> gVisor works much like User Mode Linux, and I suspect much like the
> Windows Subsystem for Linux in that it uses the x86_64's hardware
> virtualization extensions (so it has the security fencing much like a
> VM) but instead of emulating hardware, instead the emulation layer is
> done at the system call level (so it's more efficient than a VM, since
> there is no guest kernel).
> 
> [2] https://cloudplatform.googleblog.com/2018/05/Open-sourcing-gVisor-a-sandboxed-container-runtime.html
> [3] https://github.com/google/gvisor
> 
> File systems can be implemented using Gophers[4] in a separate
> process, where the communication between the gVisor sandbox and the
> Gopher is via the 9P2000.L protocol.  This means that if you want to
> try to exploit a buffer overflow in the userspace file system, first
> you have to get past the system call validation checks done by the
> gVisor Sentry process (which is written in Go which makes this rather
> more difficult, especially since the Sentry process itself is
> protected using seccomp[5]).  Then the buffer overflow attack has to
> make it past the 9P protocol encoding/decoding, and then survive the
> 9P protocol validation checks in the Gopher.  The Gopher process
> provides an emulated file system service using the Cloud Provider's
> internal cluster storage services, much like in GCE, the Persistent
> Disk service provides an emulated block device service.
> 
> [4] https://news.ycombinator.com/item?id=16979126
> [5] https://news.ycombinator.com/item?id=16976557
> 
> This whole system was designed with security first and foremost.  Of
> course, we also want it to pass the file system checks, which is why
> were using xfstests.
> 
> The way we actually tested the gVisor file system was via a Docker
> container (the Dockerfile[6] is in the xfstests-bld git repo) which
> would then get consumed by gVisor's Docker/Kubernetes integration
> layer.
> 
> [6] https://github.com/tytso/xfstests-bld/blob/master/Dockerfile
> 
> Anyway, back in September, 2016, Dave Chinner was peeved that I
> couldn't give this full description, and I'm glad to say, now we can
> finally rectify that gap.  :-)
> 
> Could this commit therefore please be considered for inclusion in
> xfstests upstream?

I still think it's useful, and thanks for resending with such detailed
information! And I'm fine with the 'local' file system type. But I may
need some time to do careful testing and go into the details. Just some
random comments inline.

> 
> Many thanks!
> 
> 						- Ted
> 
> 
> From 8b40b28866dca119d0c807c31ae48f153ec2dc53 Mon Sep 17 00:00:00 2001
> From: Theodore Ts'o <tytso@mit.edu>
> Date: Sat, 17 Sep 2016 19:08:18 -0400
> Subject: [PATCH] common: add support for the "local" file system type
> 
> It is sometimes useful to be able to test the local file system
> provided in a restricted execution environment (such as that which is
> provided by Docker, for example) where it is not possible to mount and
> unmount the file system under test.
> 
> To support this test case, add support for a new file system type
> called "local".  The TEST_DEV and SCRATCH_DEV should be have a
> non-block device format (e.g., local:/test or local:/scratch), and the

Does it require a non-block device format in this version of the patch?
I don't think so, as we have the new 'local' FSTYP introduced now.

> TEST_DIR and SCRATCH_MNT directories should be pre-existing
> directories provided by the execution environment.
> 
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> ---
>  common/rc | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---

We really need some documentation added in README :)

>  1 file changed, 70 insertions(+), 3 deletions(-)
> 
> diff --git a/common/rc b/common/rc
> index 9ffab7fd..d5cb0fe4 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -351,6 +351,18 @@ _supports_filetype()
>  	esac
>  }
>  
> +_local_validate_mount_opt()
> +{
> +    case "$*" in
> +	ro|ro,*|*,ro) _notrun "ro mount option not supported" ;;
> +	*nosuid*) _notrun "nosuid mount option not supported" ;;
> +	*noatime*) _notrun "noatime mount option not supported" ;;
> +	*relatime*) _notrun "relatime mount option not supported" ;;
> +	*diratime*) _notrun "diratime mount option not supported" ;;
> +	*strictatime*) _notrun "strictatime mount option not supported" ;;
> +    esac
> +}

Would be good to have some comments on why these mount options are not
supported for 'local'.

> +
>  # mount scratch device with given options but don't check mount status
>  _try_scratch_mount()
>  {
> @@ -376,6 +388,9 @@ _scratch_unmount()
>  	btrfs)
>  		$UMOUNT_PROG $SCRATCH_MNT
>  		;;
> +	local)
> +                rm -rf $SCRATCH_MNT/*
> +                ;;

We do this in _scratch_mkfs by calling _scratch_cleanup_files. I noticed
that you already did this in _scratch_mkfs, just return here for
'local'?

>  	*)
>  		$UMOUNT_PROG $SCRATCH_DEV
>  		;;
> @@ -386,6 +401,10 @@ _scratch_remount()
>  {
>      local opts="$1"
>  
> +    if [ "$FSTYP" = "local" ]; then
> +	_local_validate_mount_opt "$*"
> +	return 0;
> +    fi
>      if test -n "$opts"; then
>  	mount -o "remount,$opts" $SCRATCH_MNT
>      fi
> @@ -395,7 +414,7 @@ _scratch_cycle_mount()
>  {
>      local opts="$1"
>  
> -    if [ "$FSTYP" = tmpfs ]; then
> +    if [ "$FSTYP" = "tmpfs" -o "$FSTYP" = "local" ] ; then
>  	_scratch_remount "$opts"
>  	return
>      fi
> @@ -429,6 +448,10 @@ _test_mount()
>          _overlay_test_mount $*
>          return $?
>      fi
> +    if [ "$FSTYP" == "local" ]; then
> +        mkdir -p $TEST_DIR
> +	return $?
> +    fi

$TEST_DIR is guaranteed to be there (in common/config at initialization
time and in _require_test ). Perhaps we can just return in the 'local'
case?

>      _test_options mount
>      _mount -t $FSTYP $TEST_OPTIONS $TEST_FS_MOUNT_OPTS $SELINUX_MOUNT_OPTIONS $* $TEST_DEV $TEST_DIR
>  }
> @@ -437,7 +460,7 @@ _test_unmount()
>  {
>  	if [ "$FSTYP" == "overlay" ]; then
>  		_overlay_test_unmount
> -	else
> +	elif [ "$FSTYP" != "local" ]; then
>  		$UMOUNT_PROG $TEST_DEV
>  	fi
>  }
> @@ -723,7 +746,7 @@ _scratch_mkfs()
>  	local mkfs_status
>  
>  	case $FSTYP in
> -	nfs*|cifs|ceph|overlay|glusterfs|pvfs2|9p)
> +	nfs*|cifs|ceph|overlay|glusterfs|pvfs2|9p|local)
>  		# unable to re-create this fstyp, just remove all files in
>  		# $SCRATCH_MNT to avoid EEXIST caused by the leftover files
>  		# created in previous runs
> @@ -1465,6 +1488,10 @@ _check_mounted_on()
>  	local mnt=$4
>  	local type=$5
>  
> +	if [ "$FSTYP" == "local" ]; then
> +		return 0
> +	fi
> +
>  	# find $dev as the source, and print result in "$dev $mnt" format
>  	local mount_rec=`findmnt -rncv -S $dev -o SOURCE,TARGET`
>  	[ -n "$mount_rec" ] || return 1 # 1 = not mounted
> @@ -1562,6 +1589,13 @@ _require_scratch_nocheck()
>  			_notrun "this test requires a valid \$SCRATCH_MNT"
>  		fi
>  		;;
> +	local)
> +		if [ -z "$SCRATCH_DEV" -o ! -d "$SCRATCH_MNT" ];
> +		then
> +		    _notrun "this test requires a valid \$SCRATCH_MNT and unique $SCRATCH_DEV"
> +		fi
> +		return 0
> +		;;
>  	*)
>  		 if [ -z "$SCRATCH_DEV" -o "`_is_block_dev "$SCRATCH_DEV"`" = "" ]
>  		 then
> @@ -1683,6 +1717,13 @@ _require_test()
>  			_notrun "this test requires a valid \$TEST_DIR"
>  		fi
>  		;;
> +	local)
> +		if [ -z "$TEST_DEV" -o ! -d "$TEST_DIR" ];
> +		then
> +		    _notrun "this test requires a valid \$TEST_DIR and unique $TEST_DEV"
> +		fi
> +		return 0
> +		;;

It seems $SCRATCH_DEV and $TEST_DEV are not important for 'local' type,
as long as we have SCRATCH_MNT and/or TEST_DIR defined as directories.

Thanks,
Eryu

>  	*)
>  		 if [ -z "$TEST_DEV" ] || [ "`_is_block_dev "$TEST_DEV"`" = "" ]
>  		 then
> @@ -2438,6 +2479,10 @@ _remount()
>      local device=$1
>      local mode=$2
>  
> +    if [ "$FSTYP" == "local" ] ; then
> +       return 0
> +    fi
> +
>      if ! mount -o remount,$mode $device
>      then
>          echo "_remount: failed to remount filesystem on $device as $mode"
> @@ -2483,6 +2528,10 @@ _mount_or_remount_rw()
>  	local device=$2
>  	local mountpoint=$3
>  
> +	if [ "$FSTYP" == "local" ] ; then
> +	    return 0
> +	fi
> +
>  	if [ $USE_REMOUNT -eq 0 ]; then
>  		if [ "$FSTYP" != "overlay" ]; then
>  			_mount -t $FSTYP $mount_opts $device $mountpoint
> @@ -2636,6 +2685,9 @@ _check_test_fs()
>      ubifs)
>  	# there is no fsck program for ubifs yet
>  	;;
> +    local)
> +	# no way to check consistency for local
> +	;;
>      *)
>  	_check_generic_filesystem $TEST_DEV
>  	;;
> @@ -2691,6 +2743,9 @@ _check_scratch_fs()
>      ubifs)
>  	# there is no fsck program for ubifs yet
>  	;;
> +    local)
> +	# no way to check consistency for local
> +	;;
>      *)
>  	_check_generic_filesystem $device
>  	;;
> @@ -3003,6 +3058,9 @@ _require_fio()
>  # Does freeze work on this fs?
>  _require_freeze()
>  {
> +	if [ "$FSTYP" == "local" ]; then
> +		_notrun "local does not support freeze"
> +	fi
>  	xfs_freeze -f "$TEST_DIR" >/dev/null 2>&1
>  	local result=$?
>  	xfs_freeze -u "$TEST_DIR" >/dev/null 2>&1
> @@ -3024,6 +3082,9 @@ _require_scratch_shutdown()
>  {
>  	[ -x src/godown ] || _notrun "src/godown executable not found"
>  
> +	if [ "$FSTYP" == "local" ]; then
> +		_notrun "local does not support shutdown"
> +	fi
>  	_scratch_mkfs > /dev/null 2>&1 || _notrun "_scratch_mkfs failed on $SCRATCH_DEV"
>  	_scratch_mount
>  
> @@ -3049,6 +3110,9 @@ _require_scratch_shutdown()
>  # Does dax mount option work on this dev/fs?
>  _require_scratch_dax()
>  {
> +	if [ "$FSTYP" == "local" ]; then
> +		_notrun "local does not support dax"
> +	fi
>  	_require_scratch
>  	_scratch_mkfs > /dev/null 2>&1
>  	_try_scratch_mount -o dax || \
> @@ -3063,6 +3127,9 @@ _require_scratch_dax()
>  # Does norecovery support by this fs?
>  _require_norecovery()
>  {
> +	if [ "$FSTYP" == "local" ]; then
> +		_notrun "local does not support norecovery"
> +	fi
>  	_try_scratch_mount -o ro,norecovery || \
>  		_notrun "$FSTYP does not support norecovery"
>  	_scratch_unmount
> -- 
> 2.16.1.72.g5be1f00a9a
> 
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Eryu Guan May 12, 2018, 8:42 a.m. UTC | #5
Hi Ted,

On Wed, May 02, 2018 at 11:43:40PM -0400, Theodore Y. Ts'o wrote:

[snip the background details]

> From 8b40b28866dca119d0c807c31ae48f153ec2dc53 Mon Sep 17 00:00:00 2001
> From: Theodore Ts'o <tytso@mit.edu>
> Date: Sat, 17 Sep 2016 19:08:18 -0400
> Subject: [PATCH] common: add support for the "local" file system type
> 
> It is sometimes useful to be able to test the local file system
> provided in a restricted execution environment (such as that which is
> provided by Docker, for example) where it is not possible to mount and
> unmount the file system under test.
> 
> To support this test case, add support for a new file system type
> called "local".  The TEST_DEV and SCRATCH_DEV should be have a
> non-block device format (e.g., local:/test or local:/scratch), and the
> TEST_DIR and SCRATCH_MNT directories should be pre-existing
> directories provided by the execution environment.
> 
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>

I tested the patch with XFS and ext4 as the mounted underlying
filesystem for multiple rounds and found some more issues (in addition
to previous review comments) that need to be addressed. I'll reply
inline.

> ---
>  common/rc | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 70 insertions(+), 3 deletions(-)

I think we need a new "-local" option in './check' to do some initial
setups, e.g. FSTYP=local, as other fs types that can't be retrieved by
running blkid on $TEST_DEV.

Also need some documentations in README to describe "local"'s use case
and mention that TEST_DEV and SCRATCH_DEV should be have a non-block
device format.

> 
> diff --git a/common/rc b/common/rc
> index 9ffab7fd..d5cb0fe4 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -351,6 +351,18 @@ _supports_filetype()
>  	esac
>  }
>  
> +_local_validate_mount_opt()
> +{
> +    case "$*" in
> +	ro|ro,*|*,ro) _notrun "ro mount option not supported" ;;
> +	*nosuid*) _notrun "nosuid mount option not supported" ;;
> +	*noatime*) _notrun "noatime mount option not supported" ;;
> +	*relatime*) _notrun "relatime mount option not supported" ;;
> +	*diratime*) _notrun "diratime mount option not supported" ;;
> +	*strictatime*) _notrun "strictatime mount option not supported" ;;
> +    esac
> +}
> +
>  # mount scratch device with given options but don't check mount status
>  _try_scratch_mount()
>  {

We need to add a check for "local" in _try_scratch_mount() to let it do
nothing for "local" too, otherwise 'FSTYP=local ./check' won't run for
me, as _scratch_mount() failed and exit the test in 'check' line 629.

(Note that the exit on _scratch_mount() failure behavior was introduced
by commit 69eb6281a9d3 ("fstests: _fail test by default when
_scratch_mount fails"))

> @@ -376,6 +388,9 @@ _scratch_unmount()
>  	btrfs)
>  		$UMOUNT_PROG $SCRATCH_MNT
>  		;;
> +	local)
> +                rm -rf $SCRATCH_MNT/*
> +                ;;

As noted in previous review, we could just return for 'local' in
_scratch_unmount(), _scratch_mkfs() already removed all the files there.

>  	*)
>  		$UMOUNT_PROG $SCRATCH_DEV
>  		;;
> @@ -386,6 +401,10 @@ _scratch_remount()
>  {
>      local opts="$1"
>  
> +    if [ "$FSTYP" = "local" ]; then
> +	_local_validate_mount_opt "$*"
> +	return 0;
> +    fi

I found that there're more places that need to do
_local_validate_mount_opt, e.g. in _try_scratch_mount() and _test_mount,
otherwise tests that use _try_scratch_mount to do the remount would
fail, like generic/294.

>      if test -n "$opts"; then
>  	mount -o "remount,$opts" $SCRATCH_MNT
>      fi
> @@ -395,7 +414,7 @@ _scratch_cycle_mount()
>  {
>      local opts="$1"
>  
> -    if [ "$FSTYP" = tmpfs ]; then
> +    if [ "$FSTYP" = "tmpfs" -o "$FSTYP" = "local" ] ; then
>  	_scratch_remount "$opts"
>  	return
>      fi
> @@ -429,6 +448,10 @@ _test_mount()
>          _overlay_test_mount $*
>          return $?
>      fi
> +    if [ "$FSTYP" == "local" ]; then
> +        mkdir -p $TEST_DIR

Probably need _local_validate_mount_opt here as mentioned above.

And there're some tests or functions that call umount on $SCRATCH_MNT
directly, which would cause the underlying filesystem to be umounted if
it can be umounted (thouth this is not an intended use case for "local",
I think it's better to fix them too). e.g.

generic/034 generic/330 and generic/332 need to use _scratch_unmount
instead of a bare umount.

All the "$UMOUNT_PROG $SCRATCH_MNT"s in dm device helper functions, we
need to change them to umount the actual device, e.g. $FLAKEY_DEV

generic/108 needs to umount $SCSI_DEBUG_DEV in _cleanup()

Similarly, generic/459 needs to umount the lvm snapshot device
/dev/mapper/$vgname-$snapname

Thanks,
Eryu

> +	return $?
> +    fi
>      _test_options mount
>      _mount -t $FSTYP $TEST_OPTIONS $TEST_FS_MOUNT_OPTS $SELINUX_MOUNT_OPTIONS $* $TEST_DEV $TEST_DIR
>  }
> @@ -437,7 +460,7 @@ _test_unmount()
>  {
>  	if [ "$FSTYP" == "overlay" ]; then
>  		_overlay_test_unmount
> -	else
> +	elif [ "$FSTYP" != "local" ]; then
>  		$UMOUNT_PROG $TEST_DEV
>  	fi
>  }
> @@ -723,7 +746,7 @@ _scratch_mkfs()
>  	local mkfs_status
>  
>  	case $FSTYP in
> -	nfs*|cifs|ceph|overlay|glusterfs|pvfs2|9p)
> +	nfs*|cifs|ceph|overlay|glusterfs|pvfs2|9p|local)
>  		# unable to re-create this fstyp, just remove all files in
>  		# $SCRATCH_MNT to avoid EEXIST caused by the leftover files
>  		# created in previous runs
> @@ -1465,6 +1488,10 @@ _check_mounted_on()
>  	local mnt=$4
>  	local type=$5
>  
> +	if [ "$FSTYP" == "local" ]; then
> +		return 0
> +	fi
> +
>  	# find $dev as the source, and print result in "$dev $mnt" format
>  	local mount_rec=`findmnt -rncv -S $dev -o SOURCE,TARGET`
>  	[ -n "$mount_rec" ] || return 1 # 1 = not mounted
> @@ -1562,6 +1589,13 @@ _require_scratch_nocheck()
>  			_notrun "this test requires a valid \$SCRATCH_MNT"
>  		fi
>  		;;
> +	local)
> +		if [ -z "$SCRATCH_DEV" -o ! -d "$SCRATCH_MNT" ];
> +		then
> +		    _notrun "this test requires a valid \$SCRATCH_MNT and unique $SCRATCH_DEV"
> +		fi
> +		return 0
> +		;;
>  	*)
>  		 if [ -z "$SCRATCH_DEV" -o "`_is_block_dev "$SCRATCH_DEV"`" = "" ]
>  		 then
> @@ -1683,6 +1717,13 @@ _require_test()
>  			_notrun "this test requires a valid \$TEST_DIR"
>  		fi
>  		;;
> +	local)
> +		if [ -z "$TEST_DEV" -o ! -d "$TEST_DIR" ];
> +		then
> +		    _notrun "this test requires a valid \$TEST_DIR and unique $TEST_DEV"
> +		fi
> +		return 0
> +		;;
>  	*)
>  		 if [ -z "$TEST_DEV" ] || [ "`_is_block_dev "$TEST_DEV"`" = "" ]
>  		 then
> @@ -2438,6 +2479,10 @@ _remount()
>      local device=$1
>      local mode=$2
>  
> +    if [ "$FSTYP" == "local" ] ; then
> +       return 0
> +    fi
> +
>      if ! mount -o remount,$mode $device
>      then
>          echo "_remount: failed to remount filesystem on $device as $mode"
> @@ -2483,6 +2528,10 @@ _mount_or_remount_rw()
>  	local device=$2
>  	local mountpoint=$3
>  
> +	if [ "$FSTYP" == "local" ] ; then
> +	    return 0
> +	fi
> +
>  	if [ $USE_REMOUNT -eq 0 ]; then
>  		if [ "$FSTYP" != "overlay" ]; then
>  			_mount -t $FSTYP $mount_opts $device $mountpoint
> @@ -2636,6 +2685,9 @@ _check_test_fs()
>      ubifs)
>  	# there is no fsck program for ubifs yet
>  	;;
> +    local)
> +	# no way to check consistency for local
> +	;;
>      *)
>  	_check_generic_filesystem $TEST_DEV
>  	;;
> @@ -2691,6 +2743,9 @@ _check_scratch_fs()
>      ubifs)
>  	# there is no fsck program for ubifs yet
>  	;;
> +    local)
> +	# no way to check consistency for local
> +	;;
>      *)
>  	_check_generic_filesystem $device
>  	;;
> @@ -3003,6 +3058,9 @@ _require_fio()
>  # Does freeze work on this fs?
>  _require_freeze()
>  {
> +	if [ "$FSTYP" == "local" ]; then
> +		_notrun "local does not support freeze"
> +	fi
>  	xfs_freeze -f "$TEST_DIR" >/dev/null 2>&1
>  	local result=$?
>  	xfs_freeze -u "$TEST_DIR" >/dev/null 2>&1
> @@ -3024,6 +3082,9 @@ _require_scratch_shutdown()
>  {
>  	[ -x src/godown ] || _notrun "src/godown executable not found"
>  
> +	if [ "$FSTYP" == "local" ]; then
> +		_notrun "local does not support shutdown"
> +	fi
>  	_scratch_mkfs > /dev/null 2>&1 || _notrun "_scratch_mkfs failed on $SCRATCH_DEV"
>  	_scratch_mount
>  
> @@ -3049,6 +3110,9 @@ _require_scratch_shutdown()
>  # Does dax mount option work on this dev/fs?
>  _require_scratch_dax()
>  {
> +	if [ "$FSTYP" == "local" ]; then
> +		_notrun "local does not support dax"
> +	fi
>  	_require_scratch
>  	_scratch_mkfs > /dev/null 2>&1
>  	_try_scratch_mount -o dax || \
> @@ -3063,6 +3127,9 @@ _require_scratch_dax()
>  # Does norecovery support by this fs?
>  _require_norecovery()
>  {
> +	if [ "$FSTYP" == "local" ]; then
> +		_notrun "local does not support norecovery"
> +	fi
>  	_try_scratch_mount -o ro,norecovery || \
>  		_notrun "$FSTYP does not support norecovery"
>  	_scratch_unmount
> -- 
> 2.16.1.72.g5be1f00a9a
> 
> --
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diff mbox

Patch

diff --git a/common/rc b/common/rc
index 9ffab7fd..d5cb0fe4 100644
--- a/common/rc
+++ b/common/rc
@@ -351,6 +351,18 @@  _supports_filetype()
 	esac
 }
 
+_local_validate_mount_opt()
+{
+    case "$*" in
+	ro|ro,*|*,ro) _notrun "ro mount option not supported" ;;
+	*nosuid*) _notrun "nosuid mount option not supported" ;;
+	*noatime*) _notrun "noatime mount option not supported" ;;
+	*relatime*) _notrun "relatime mount option not supported" ;;
+	*diratime*) _notrun "diratime mount option not supported" ;;
+	*strictatime*) _notrun "strictatime mount option not supported" ;;
+    esac
+}
+
 # mount scratch device with given options but don't check mount status
 _try_scratch_mount()
 {
@@ -376,6 +388,9 @@  _scratch_unmount()
 	btrfs)
 		$UMOUNT_PROG $SCRATCH_MNT
 		;;
+	local)
+                rm -rf $SCRATCH_MNT/*
+                ;;
 	*)
 		$UMOUNT_PROG $SCRATCH_DEV
 		;;
@@ -386,6 +401,10 @@  _scratch_remount()
 {
     local opts="$1"
 
+    if [ "$FSTYP" = "local" ]; then
+	_local_validate_mount_opt "$*"
+	return 0;
+    fi
     if test -n "$opts"; then
 	mount -o "remount,$opts" $SCRATCH_MNT
     fi
@@ -395,7 +414,7 @@  _scratch_cycle_mount()
 {
     local opts="$1"
 
-    if [ "$FSTYP" = tmpfs ]; then
+    if [ "$FSTYP" = "tmpfs" -o "$FSTYP" = "local" ] ; then
 	_scratch_remount "$opts"
 	return
     fi
@@ -429,6 +448,10 @@  _test_mount()
         _overlay_test_mount $*
         return $?
     fi
+    if [ "$FSTYP" == "local" ]; then
+        mkdir -p $TEST_DIR
+	return $?
+    fi
     _test_options mount
     _mount -t $FSTYP $TEST_OPTIONS $TEST_FS_MOUNT_OPTS $SELINUX_MOUNT_OPTIONS $* $TEST_DEV $TEST_DIR
 }
@@ -437,7 +460,7 @@  _test_unmount()
 {
 	if [ "$FSTYP" == "overlay" ]; then
 		_overlay_test_unmount
-	else
+	elif [ "$FSTYP" != "local" ]; then
 		$UMOUNT_PROG $TEST_DEV
 	fi
 }
@@ -723,7 +746,7 @@  _scratch_mkfs()
 	local mkfs_status
 
 	case $FSTYP in
-	nfs*|cifs|ceph|overlay|glusterfs|pvfs2|9p)
+	nfs*|cifs|ceph|overlay|glusterfs|pvfs2|9p|local)
 		# unable to re-create this fstyp, just remove all files in
 		# $SCRATCH_MNT to avoid EEXIST caused by the leftover files
 		# created in previous runs
@@ -1465,6 +1488,10 @@  _check_mounted_on()
 	local mnt=$4
 	local type=$5
 
+	if [ "$FSTYP" == "local" ]; then
+		return 0
+	fi
+
 	# find $dev as the source, and print result in "$dev $mnt" format
 	local mount_rec=`findmnt -rncv -S $dev -o SOURCE,TARGET`
 	[ -n "$mount_rec" ] || return 1 # 1 = not mounted
@@ -1562,6 +1589,13 @@  _require_scratch_nocheck()
 			_notrun "this test requires a valid \$SCRATCH_MNT"
 		fi
 		;;
+	local)
+		if [ -z "$SCRATCH_DEV" -o ! -d "$SCRATCH_MNT" ];
+		then
+		    _notrun "this test requires a valid \$SCRATCH_MNT and unique $SCRATCH_DEV"
+		fi
+		return 0
+		;;
 	*)
 		 if [ -z "$SCRATCH_DEV" -o "`_is_block_dev "$SCRATCH_DEV"`" = "" ]
 		 then
@@ -1683,6 +1717,13 @@  _require_test()
 			_notrun "this test requires a valid \$TEST_DIR"
 		fi
 		;;
+	local)
+		if [ -z "$TEST_DEV" -o ! -d "$TEST_DIR" ];
+		then
+		    _notrun "this test requires a valid \$TEST_DIR and unique $TEST_DEV"
+		fi
+		return 0
+		;;
 	*)
 		 if [ -z "$TEST_DEV" ] || [ "`_is_block_dev "$TEST_DEV"`" = "" ]
 		 then
@@ -2438,6 +2479,10 @@  _remount()
     local device=$1
     local mode=$2
 
+    if [ "$FSTYP" == "local" ] ; then
+       return 0
+    fi
+
     if ! mount -o remount,$mode $device
     then
         echo "_remount: failed to remount filesystem on $device as $mode"
@@ -2483,6 +2528,10 @@  _mount_or_remount_rw()
 	local device=$2
 	local mountpoint=$3
 
+	if [ "$FSTYP" == "local" ] ; then
+	    return 0
+	fi
+
 	if [ $USE_REMOUNT -eq 0 ]; then
 		if [ "$FSTYP" != "overlay" ]; then
 			_mount -t $FSTYP $mount_opts $device $mountpoint
@@ -2636,6 +2685,9 @@  _check_test_fs()
     ubifs)
 	# there is no fsck program for ubifs yet
 	;;
+    local)
+	# no way to check consistency for local
+	;;
     *)
 	_check_generic_filesystem $TEST_DEV
 	;;
@@ -2691,6 +2743,9 @@  _check_scratch_fs()
     ubifs)
 	# there is no fsck program for ubifs yet
 	;;
+    local)
+	# no way to check consistency for local
+	;;
     *)
 	_check_generic_filesystem $device
 	;;
@@ -3003,6 +3058,9 @@  _require_fio()
 # Does freeze work on this fs?
 _require_freeze()
 {
+	if [ "$FSTYP" == "local" ]; then
+		_notrun "local does not support freeze"
+	fi
 	xfs_freeze -f "$TEST_DIR" >/dev/null 2>&1
 	local result=$?
 	xfs_freeze -u "$TEST_DIR" >/dev/null 2>&1
@@ -3024,6 +3082,9 @@  _require_scratch_shutdown()
 {
 	[ -x src/godown ] || _notrun "src/godown executable not found"
 
+	if [ "$FSTYP" == "local" ]; then
+		_notrun "local does not support shutdown"
+	fi
 	_scratch_mkfs > /dev/null 2>&1 || _notrun "_scratch_mkfs failed on $SCRATCH_DEV"
 	_scratch_mount
 
@@ -3049,6 +3110,9 @@  _require_scratch_shutdown()
 # Does dax mount option work on this dev/fs?
 _require_scratch_dax()
 {
+	if [ "$FSTYP" == "local" ]; then
+		_notrun "local does not support dax"
+	fi
 	_require_scratch
 	_scratch_mkfs > /dev/null 2>&1
 	_try_scratch_mount -o dax || \
@@ -3063,6 +3127,9 @@  _require_scratch_dax()
 # Does norecovery support by this fs?
 _require_norecovery()
 {
+	if [ "$FSTYP" == "local" ]; then
+		_notrun "local does not support norecovery"
+	fi
 	_try_scratch_mount -o ro,norecovery || \
 		_notrun "$FSTYP does not support norecovery"
 	_scratch_unmount