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Date: Wed, 30 Jun 2021 18:46:22 +0300
From: Amir Goldstein <amir73il@...il.com>
To: Luis Henriques <lhenriques@...e.de>
Cc: kernel test robot <oliver.sang@...el.com>,
0day robot <lkp@...el.com>,
Nicolas Boichat <drinkcat@...omium.org>,
Olga Kornievskaia <aglo@...ch.edu>,
LKML <linux-kernel@...r.kernel.org>, lkp@...ts.01.org,
Alexander Viro <viro@...iv.linux.org.uk>,
linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: [vfs] 94a4dd06a6: xfstests.generic.263.fail
On Fri, May 14, 2021 at 2:03 PM Luis Henriques <lhenriques@...e.de> wrote:
>
> kernel test robot <oliver.sang@...el.com> writes:
>
> > Greeting,
> >
> > FYI, we noticed the following commit (built with gcc-9):
> >
> > commit: 94a4dd06a6bbf3978b0bb1dddc2d8ec4e5bcad26 ("[PATCH v9] vfs: fix copy_file_range regression in cross-fs copies")
> > url: https://github.com/0day-ci/linux/commits/Luis-Henriques/vfs-fix-copy_file_range-regression-in-cross-fs-copies/20210510-170804
> > base: https://git.kernel.org/cgit/linux/kernel/git/viro/vfs.git for-next
> >
> > in testcase: xfstests
> > version: xfstests-x86_64-73c0871-1_20210401
> > with following parameters:
> >
> > disk: 4HDD
> > fs: xfs
> > test: generic-group-13
> > ucode: 0x21
> >
> > test-description: xfstests is a regression test suite for xfs and other files ystems.
> > test-url: git://git.kernel.org/pub/scm/fs/xfs/xfstests-dev.git
> >
> >
> > on test machine: 4 threads 1 sockets Intel(R) Core(TM) i3-3220 CPU @ 3.30GHz with 8G memory
> >
> > caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
> >
> >
> >
> >
> > If you fix the issue, kindly add following tag
> > Reported-by: kernel test robot <oliver.sang@...el.com>
> >
> > 2021-05-11 11:28:23 export TEST_DIR=/fs/sda1
> > 2021-05-11 11:28:23 export TEST_DEV=/dev/sda1
> > 2021-05-11 11:28:23 export FSTYP=xfs
> > 2021-05-11 11:28:23 export SCRATCH_MNT=/fs/scratch
> > 2021-05-11 11:28:23 mkdir /fs/scratch -p
> > 2021-05-11 11:28:23 export SCRATCH_DEV=/dev/sda4
> > 2021-05-11 11:28:23 export SCRATCH_LOGDEV=/dev/sda2
> > 2021-05-11 11:28:23 sed "s:^:generic/:" //lkp/benchmarks/xfstests/tests/generic-group-13
> > 2021-05-11 11:28:23 ./check generic/260 generic/261 generic/262 generic/263 generic/264 generic/265 generic/266 generic/267 generic/268 generic/269 generic/270 generic/271 generic/272 generic/273 generic/274 generic/275 generic/276 generic/277 generic/278 generic/279
> > FSTYP -- xfs (debug)
> > PLATFORM -- Linux/x86_64 lkp-ivb-d02 5.12.0-rc6-00061-g94a4dd06a6bb #1 SMP Tue May 11 00:58:17 CST 2021
> > MKFS_OPTIONS -- -f -bsize=4096 /dev/sda4
> > MOUNT_OPTIONS -- /dev/sda4 /fs/scratch
> >
> > generic/260 [not run] FITRIM not supported on /fs/scratch
> > generic/261 [not run] Reflink not supported by scratch filesystem type: xfs
> > generic/262 [not run] Reflink not supported by scratch filesystem type: xfs
> > generic/263 [failed, exit status 1]- output mismatch (see /lkp/benchmarks/xfstests/results//generic/263.out.bad)
> > --- tests/generic/263.out 2021-04-01 03:07:08.000000000 +0000
> > +++ /lkp/benchmarks/xfstests/results//generic/263.out.bad 2021-05-11 11:28:29.773460096 +0000
> > @@ -1,3 +1,32 @@
> > QA output created by 263
> > fsx -N 10000 -o 8192 -l 500000 -r PSIZE -t BSIZE -w BSIZE -Z
> > -fsx -N 10000 -o 128000 -l 500000 -r PSIZE -t BSIZE -w BSIZE -Z
> > +Seed set to 1
> > +main: filesystem does not support clone range, disabling!
> > +main: filesystem does not support dedupe range, disabling!
> > +skipping zero size read
> > ...
> > (Run 'diff -u /lkp/benchmarks/xfstests/tests/generic/263.out /lkp/benchmarks/xfstests/results//generic/263.out.bad' to see the entire diff)
> > generic/264 [not run] Reflink not supported by scratch filesystem type: xfs
> > generic/265 [not run] Reflink not supported by scratch filesystem type: xfs
> > generic/266 [not run] Reflink not supported by scratch filesystem type: xfs
> > generic/267 [not run] Reflink not supported by scratch filesystem type: xfs
> > generic/268 [not run] Reflink not supported by scratch filesystem type: xfs
> > generic/269 48s
> > generic/270 61s
> > generic/271 [not run] Reflink not supported by scratch filesystem type: xfs
> > generic/272 [not run] Reflink not supported by scratch filesystem type: xfs
> > generic/273 17s
> > generic/274 14s
> > generic/275 11s
> > generic/276 [not run] Reflink not supported by scratch filesystem type: xfs
> > generic/277 3s
> > generic/278 [not run] Reflink not supported by scratch filesystem type: xfs
> > generic/279 [not run] Reflink not supported by scratch filesystem type: xfs
> > Ran: generic/260 generic/261 generic/262 generic/263 generic/264 generic/265 generic/266 generic/267 generic/268 generic/269 generic/270 generic/271 generic/272 generic/273 generic/274 generic/275 generic/276 generic/277 generic/278 generic/279
> > Not run: generic/260 generic/261 generic/262 generic/264 generic/265 generic/266 generic/267 generic/268 generic/271 generic/272 generic/276 generic/278 generic/279
> > Failures: generic/263
> > Failed 1 of 20 tests
>
> OK, I see what's going on. There are 2 issues: one with patch and another
> one with the test itself.
>
> The CFR syscall should have been disabled in this test but it isn't
> because the test tries to copy 1 byte from a zero-sized file:
>
> int
> test_copy_range(void)
> {
> loff_t o1 = 0, o2 = 1;
>
> if (syscall(__NR_copy_file_range, fd, &o1, fd, &o2, 1, 0) == -1 &&
> (errno == ENOSYS || errno == EOPNOTSUPP || errno == ENOTTY)) {
> if (!quiet)
> fprintf(stderr,
> "main: filesystem does not support "
> "copy range, disabling!\n");
> return 0;
> }
>
> return 1;
> }
>
> The syscall is doing an early '0' return because the file size is < len.
>
> Fixing the kernel should probably be as easy as removing the
> short-circuiting check in vfs_copy_file_range():
>
> if (len == 0)
> return 0;
>
> This will force the filesystems code to handle '0' size copies but will
> also make sure -EOPNOTSUPP is returned in this case.
>
Sorry for the late reply.
The solution above is correct.
That is aligned with the behavior of vfs_clone_file_range().
Need to call into the filesystem method also with 0 length
in order to learn about CFR support of this filesystem instance.
> Alternatively, we could have something like:
>
> if (len == 0) {
> if (file_out->f_op->copy_file_range)
> return 0;
> else
> return -EOPNOTSUPP;
> }
>
This does not catch the case of a filesystem driver that has
CFR method but a filesystem instance does not support CFR.
For example, overlayfs with ext4 as upper fs.
> What do you guys think is the right thing to do?
>
> Additionally, the test should also be fixed with something as the patch
> bellow. By making sure we have 1 byte to copy we also ensure the syscall
> will return -EOPNOTSUPP, even with the current version of the patch.
>
I don't think that the test should be fixed.
Thanks,
Amir.
> Cheers,
> --
> Luis
>
> diff --git a/ltp/fsx.c b/ltp/fsx.c
> index cd0bae55aeb8..97db594ae142 100644
> --- a/ltp/fsx.c
> +++ b/ltp/fsx.c
> @@ -1596,6 +1596,10 @@ int
> test_copy_range(void)
> {
> loff_t o1 = 0, o2 = 1;
> + int ret = 1;
> +
> + /* Make sure we have 1 byte to copy */
> + ftruncate(fd, 1);
>
> if (syscall(__NR_copy_file_range, fd, &o1, fd, &o2, 1, 0) == -1 &&
> (errno == ENOSYS || errno == EOPNOTSUPP || errno == ENOTTY)) {
> @@ -1603,10 +1607,13 @@ test_copy_range(void)
> fprintf(stderr,
> "main: filesystem does not support "
> "copy range, disabling!\n");
> - return 0;
> + ret = 0;
> }
>
> - return 1;
> + /* Restore file size */
> + ftruncate(fd, 0);
> +
> + return ret;
> }
>
> void
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