Re: [PATCH xfstests v3 2/2] generic/756: test name_to_handle_at(AT_HANDLE_MNT_ID_UNIQUE) explicitly

[Amir Goldstein <amir73il@gmail.com>]

On Wed, Sep 4, 2024 at 7:57 PM Aleksa Sarai <cyphar@cyphar.com> wrote:
>
> In order to make sure we are actually testing AT_HANDLE_MNT_ID_UNIQUE,
> add a test (based on generic/426) which runs the open_by_handle in a
> mode where it will error out if there is a problem with getting mount
> IDs. The test is skipped if the kernel doesn't support the necessary
> features.
>
> Suggested-by: Amir Goldstein <amir73il@gmail.com>
> Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>

Apart from one minor nits below, you may add:

Reviewed-by: Amir Goldstein <amir73il@gmail.com>

> ---
>  common/rc             | 24 ++++++++++++++++
>  src/open_by_handle.c  | 63 ++++++++++++++++++++++++++++++++++-------
>  tests/generic/756     | 65 +++++++++++++++++++++++++++++++++++++++++++
>  tests/generic/756.out |  5 ++++
>  4 files changed, 147 insertions(+), 10 deletions(-)
>  create mode 100755 tests/generic/756
>  create mode 100644 tests/generic/756.out
>
> diff --git a/common/rc b/common/rc
> index 9da9fe188297..0beaf2ff1126 100644
> --- a/common/rc
> +++ b/common/rc
> @@ -5178,6 +5178,30 @@ _require_fibmap()
>         rm -f $file
>  }
>
> +_require_statx_unique_mountid()
> +{
> +       # statx(STATX_MNT_ID=0x1000) was added in Linux 5.8.
> +       # statx(STATX_MNT_ID_UNIQUE=0x4000) was added in Linux 6.9.
> +       # We only need to check the latter.
> +
> +       export STATX_MNT_ID_UNIQUE=0x4000
> +       local statx_mask=$(
> +               ${XFS_IO_PROG} -c "statx -m $STATX_MNT_ID_UNIQUE -r" "$TEST_DIR" |
> +               sed -En 's/stat\.mask = (0x[0-9a-f]+)/\1/p'
> +       )
> +
> +       [[ $(( statx_mask & STATX_MNT_ID_UNIQUE )) == $((STATX_MNT_ID_UNIQUE)) ]] ||
> +               _notrun "statx does not support STATX_MNT_ID_UNIQUE on this kernel"
> +}
> +
> +_require_open_by_handle_unique_mountid()
> +{
> +       _require_test_program "open_by_handle"
> +
> +       $here/src/open_by_handle -C AT_HANDLE_MNT_ID_UNIQUE 2>&1 \
> +               || _notrun "name_to_handle_at does not support AT_HANDLE_MNT_ID_UNIQUE"
> +}
> +
>  _try_wipe_scratch_devs()
>  {
>         test -x "$WIPEFS_PROG" || return 0
> diff --git a/src/open_by_handle.c b/src/open_by_handle.c
> index 920ec7d9170b..b5c1a30abbbc 100644
> --- a/src/open_by_handle.c
> +++ b/src/open_by_handle.c
> @@ -106,9 +106,11 @@ struct handle {
>
>  void usage(void)
>  {
> -       fprintf(stderr, "usage: open_by_handle [-cludmrwapknhs] [<-i|-o> <handles_file>] <test_dir> [num_files]\n");
> +       fprintf(stderr, "usage: open_by_handle [-cludmMrwapknhs] [<-i|-o> <handles_file>] <test_dir> [num_files]\n");
> +       fprintf(stderr, "       open_by_handle -C <feature>\n");
>         fprintf(stderr, "\n");
>         fprintf(stderr, "open_by_handle -c <test_dir> [N] - create N test files under test_dir, try to get file handles and exit\n");
> +       fprintf(stderr, "open_by_handle -c <test_dir> [N] - create N test files under test_dir, try to get file handles and exit\n");
>         fprintf(stderr, "open_by_handle    <test_dir> [N] - get file handles of test files, drop caches and try to open by handle\n");
>         fprintf(stderr, "open_by_handle -n <test_dir> [N] - get file handles of test files and try to open by handle without drop caches\n");
>         fprintf(stderr, "open_by_handle -k <test_dir> [N] - get file handles of files that are kept open, drop caches and try to open by handle\n");
> @@ -117,19 +119,23 @@ void usage(void)
>         fprintf(stderr, "open_by_handle -a <test_dir> [N] - write data to test files after open by handle\n");
>         fprintf(stderr, "open_by_handle -l <test_dir> [N] - create hardlinks to test files, drop caches and try to open by handle\n");
>         fprintf(stderr, "open_by_handle -u <test_dir> [N] - unlink (hardlinked) test files, drop caches and try to open by handle\n");
> -       fprintf(stderr, "open_by_handle -U <test_dir> [N] - verify the mount ID returned with AT_HANDLE_MNT_ID_UNIQUE is correct\n");

I guess this was not supposed to be in the first patch

>         fprintf(stderr, "open_by_handle -d <test_dir> [N] - unlink test files and hardlinks, drop caches and try to open by handle\n");
>         fprintf(stderr, "open_by_handle -m <test_dir> [N] - rename test files, drop caches and try to open by handle\n");
> +       fprintf(stderr, "open_by_handle -M <test_dir> [N] - do not silently skip the mount ID verifications\n");
>         fprintf(stderr, "open_by_handle -p <test_dir>     - create/delete and try to open by handle also test_dir itself\n");
>         fprintf(stderr, "open_by_handle -i <handles_file> <test_dir> [N] - read test files handles from file and try to open by handle\n");
>         fprintf(stderr, "open_by_handle -o <handles_file> <test_dir> [N] - get file handles of test files and write handles to file\n");
>         fprintf(stderr, "open_by_handle -s <test_dir> [N] - wait in sleep loop after opening files by handle to keep them open\n");
>         fprintf(stderr, "open_by_handle -z <test_dir> [N] - query filesystem required buffer size\n");
> +       fprintf(stderr, "\n");
> +       fprintf(stderr, "open_by_handle -C <feature>      - check if <feature> is supported by the kernel.\n");
> +       fprintf(stderr, "  <feature> can be any of the following values:\n");
> +       fprintf(stderr, "  - AT_HANDLE_MNT_ID_UNIQUE\n");
>         exit(EXIT_FAILURE);
>  }
>
>  static int do_name_to_handle_at(const char *fname, struct file_handle *fh,
> -                               int bufsz)
> +                               int bufsz, bool force_check_mountid)
>  {
>         int ret;
>         int mntid_short;
> @@ -145,10 +151,15 @@ static int do_name_to_handle_at(const char *fname, struct file_handle *fh,
>                         fprintf(stderr, "%s: statx(STATX_MNT_ID): %m\n", fname);
>                         return EXIT_FAILURE;
>                 }
> -               if (!(statxbuf.stx_mask & STATX_MNT_ID))
> +               if (!(statxbuf.stx_mask & STATX_MNT_ID)) {
> +                       if (force_check_mountid) {
> +                               fprintf(stderr, "%s: statx(STATX_MNT_ID) not supported by running kernel\n", fname);
> +                               return EXIT_FAILURE;
> +                       }
>                         skip_mntid = true;
> -               else
> +               } else {
>                         statx_mntid_short = statxbuf.stx_mnt_id;
> +               }
>         }
>
>         if (!skip_mntid_unique) {
> @@ -160,10 +171,15 @@ static int do_name_to_handle_at(const char *fname, struct file_handle *fh,
>                  * STATX_MNT_ID_UNIQUE was added fairly recently in Linux 6.8, so if the
>                  * kernel doesn't give us a unique mount ID just skip it.
>                  */
> -               if (!(statxbuf.stx_mask & STATX_MNT_ID_UNIQUE))
> +               if (!(statxbuf.stx_mask & STATX_MNT_ID_UNIQUE)) {
> +                       if (force_check_mountid) {
> +                               fprintf(stderr, "%s: statx(STATX_MNT_ID_UNIQUE) not supported by running kernel\n", fname);
> +                               return EXIT_FAILURE;
> +                       }
>                         skip_mntid_unique = true;
> -               else
> +               } else {
>                         statx_mntid_unique = statxbuf.stx_mnt_id;
> +               }
>         }
>
>         fh->handle_bytes = bufsz;
> @@ -204,6 +220,10 @@ static int do_name_to_handle_at(const char *fname, struct file_handle *fh,
>                                 return EXIT_FAILURE;
>                         }
>                         /* EINVAL means AT_HANDLE_MNT_ID_UNIQUE is not supported */
> +                       if (force_check_mountid) {
> +                               fprintf(stderr, "%s: name_to_handle_at(AT_HANDLE_MNT_ID_UNIQUE) not supported by running kernel\n", fname);
> +                               return EXIT_FAILURE;
> +                       }
>                         skip_mntid_unique = true;
>                 } else {
>                         if (mntid_unique != statx_mntid_unique) {
> @@ -216,6 +236,22 @@ static int do_name_to_handle_at(const char *fname, struct file_handle *fh,
>         return 0;
>  }
>
> +static int check_feature(const char *feature)
> +{
> +       if (!strcmp(feature, "AT_HANDLE_MNT_ID_UNIQUE")) {
> +               int ret = name_to_handle_at(AT_FDCWD, ".", NULL, NULL, AT_HANDLE_MNT_ID_UNIQUE);
> +               /* If AT_HANDLE_MNT_ID_UNIQUE is supported, we get EFAULT. */
> +               if (ret < 0 && errno == EINVAL) {
> +                       fprintf(stderr, "name_to_handle_at(AT_HANDLE_MNT_ID_UNIQUE) not supported by running kernel\n");
> +                       return EXIT_FAILURE;
> +               }
> +               return 0;
> +       }
> +
> +       fprintf(stderr, "unknown feature name '%s'\n", feature);
> +       return EXIT_FAILURE;
> +}
> +
>  int main(int argc, char **argv)
>  {
>         int     i, c;
> @@ -235,16 +271,20 @@ int main(int argc, char **argv)
>         int     create = 0, delete = 0, nlink = 1, move = 0;
>         int     rd = 0, wr = 0, wrafter = 0, parent = 0;
>         int     keepopen = 0, drop_caches = 1, sleep_loop = 0;
> +       int force_check_mountid = 0;
>         int     bufsz = MAX_HANDLE_SZ;
>
>         if (argc < 2)
>                 usage();
>
> -       while ((c = getopt(argc, argv, "cludmrwapknhi:o:sz")) != -1) {
> +       while ((c = getopt(argc, argv, "cC:ludmMrwapknhi:o:sz")) != -1) {
>                 switch (c) {
>                 case 'c':
>                         create = 1;
>                         break;
> +               case 'C':
> +                       /* Check kernel feature support. */
> +                       return check_feature(optarg);
>                 case 'w':
>                         /* Write data before open_by_handle_at() */
>                         wr = 1;
> @@ -271,6 +311,9 @@ int main(int argc, char **argv)
>                 case 'm':
>                         move = 1;
>                         break;
> +               case 'M':
> +                       force_check_mountid = 1;
> +                       break;
>                 case 'p':
>                         parent = 1;
>                         break;
> @@ -403,7 +446,7 @@ int main(int argc, char **argv)
>                                 return EXIT_FAILURE;
>                         }
>                 } else {
> -                       ret = do_name_to_handle_at(fname, &handle[i].fh, bufsz);
> +                       ret = do_name_to_handle_at(fname, &handle[i].fh, bufsz, force_check_mountid);
>                         if (ret)
>                                 return EXIT_FAILURE;
>                 }
> @@ -433,7 +476,7 @@ int main(int argc, char **argv)
>                                 return EXIT_FAILURE;
>                         }
>                 } else {
> -                       ret = do_name_to_handle_at(test_dir, &dir_handle.fh, bufsz);
> +                       ret = do_name_to_handle_at(test_dir, &dir_handle.fh, bufsz, force_check_mountid);
>                         if (ret)
>                                 return EXIT_FAILURE;
>                 }
> diff --git a/tests/generic/756 b/tests/generic/756
> new file mode 100755
> index 000000000000..c7a82cfd25f4
> --- /dev/null
> +++ b/tests/generic/756
> @@ -0,0 +1,65 @@
> +#! /bin/bash
> +# SPDX-License-Identifier: GPL-2.0
> +# Copyright (C) 2017 CTERA Networks. All Rights Reserved.
> +# Copyright (C) 2024 Aleksa Sarai <cyphar@cyphar.com>
> +#
> +# FS QA Test No. 756
> +#
> +# Check stale handles pointing to unlinked files and non-stale handles pointing
> +# to linked files while verifying that u64 mount IDs are correctly returned.
> +#
> +. ./common/preamble
> +_begin_fstest auto quick exportfs
> +
> +# Import common functions.
> +. ./common/filter
> +
> +
> +# Modify as appropriate.
> +_require_test
> +# _require_exportfs and  already requires open_by_handle, but let's not count on it
> +_require_test_program "open_by_handle"
> +_require_exportfs
> +# We need both STATX_MNT_ID_UNIQUE and AT_HANDLE_MNT_ID_UNIQUE.
> +_require_statx_unique_mountid
> +_require_open_by_handle_unique_mountid
> +
> +NUMFILES=1024
> +testdir=$TEST_DIR/$seq-dir
> +mkdir -p $testdir
> +
> +# Create empty test files in test dir
> +create_test_files()
> +{
> +       local dir=$1
> +
> +       mkdir -p $dir
> +       rm -f $dir/*
> +       $here/src/open_by_handle -c $dir $NUMFILES
> +}
> +
> +# Test encode/decode file handles
> +test_file_handles()
> +{
> +       local dir=$1
> +       local opt=$2
> +
> +       echo test_file_handles $* | _filter_test_dir
> +       $here/src/open_by_handle $opt $dir $NUMFILES
> +}
> +
> +# Check stale handles to deleted files
> +create_test_files $testdir
> +test_file_handles $testdir -Md
> +
> +# Check non-stale handles to linked files
> +create_test_files $testdir
> +test_file_handles $testdir -M
> +
> +# Check non-stale handles to files that were hardlinked and original deleted
> +create_test_files $testdir
> +test_file_handles $testdir -Ml
> +test_file_handles $testdir -Mu
> +
> +status=0
> +exit
> diff --git a/tests/generic/756.out b/tests/generic/756.out
> new file mode 100644
> index 000000000000..48aed88d87b9
> --- /dev/null
> +++ b/tests/generic/756.out
> @@ -0,0 +1,5 @@
> +QA output created by 756
> +test_file_handles TEST_DIR/756-dir -Md
> +test_file_handles TEST_DIR/756-dir -M
> +test_file_handles TEST_DIR/756-dir -Ml
> +test_file_handles TEST_DIR/756-dir -Mu
> --
> 2.46.0
>