On 2024-09-04, Amir Goldstein [off-list ref] wrote:

On Wed, Sep 4, 2024 at 7:57 PM Aleksa Sarai [off-list ref] wrote:

quoted

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 <redacted>

Apart from one minor nits below, you may add:

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

quoted

---
 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

Yeah, it got mixed up when splitting the patch. I'll fix it up.

quoted

        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

-- 
Aleksa Sarai
Senior Software Engineer (Containers)
SUSE Linux GmbH
<https://www.cyphar.com/>