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Message-ID: <CAOQ4uxi5KdtD02gazgJfvUKktev39Y+otAZat=H22tKrW16ZrQ@mail.gmail.com>
Date: Wed, 4 Sep 2024 20:29:27 +0200
From: Amir Goldstein <amir73il@...il.com>
To: Aleksa Sarai <cyphar@...har.com>
Cc: fstests@...r.kernel.org, Alexander Viro <viro@...iv.linux.org.uk>,
Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, Chuck Lever <chuck.lever@...cle.com>,
Jeff Layton <jlayton@...nel.org>, Alexander Aring <alex.aring@...il.com>,
Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>,
"Liang, Kan" <kan.liang@...ux.intel.com>, Christoph Hellwig <hch@...radead.org>,
Josef Bacik <josef@...icpanda.com>, linux-fsdevel@...r.kernel.org,
linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-api@...r.kernel.org, linux-perf-users@...r.kernel.org
Subject: Re: [PATCH xfstests v3 1/2] open_by_handle: verify u32 and u64 mount IDs
On Wed, Sep 4, 2024 at 7:57 PM Aleksa Sarai <cyphar@...har.com> wrote:
>
> Now that open_by_handle_at(2) can return u64 mount IDs, do some tests to
> make sure they match properly as part of the regular open_by_handle
> tests. Also, add automatic tests for the old u32 mount IDs as well.
>
> By default, we do mount ID checks but silently skip the tests if the
> syscalls are not supported by the running kernel (to ensure the tests
> continue to work for old kernels). We will add some tests explicitly
> checking the new features (with no silent skipping) in a future patch.
>
> The u32 mount ID tests require STATX_MNT_ID (Linux 5.8), while the u64
> mount ID tests require STATX_MNT_ID_UNIQUE (Linux 6.9) and
> AT_HANDLE_MNT_ID_UNIQUE (linux-next).
>
> Link: https://lore.kernel.org/all/20240828-exportfs-u64-mount-id-v3-0-10c2c4c16708@cyphar.com/
> Signed-off-by: Aleksa Sarai <cyphar@...har.com>
Reviewed-by: Amir Goldstein <amir73il@...il.com>
> ---
> Changed in v3:
> - Make skipping completely silent in regular open_by_handle mode. [Amir Goldstein]
> - Re-add -M to turn skipping into errors and add a new test that uses
> -M, but is skipped on older kernels. [Amir Goldstein]
> - v2: <https://lore.kernel.org/all/20240902164554.928371-1-cyphar@cyphar.com/>
> Changed in v2:
> - Remove -M argument and always do the mount ID tests. [Amir Goldstein]
> - Do not error out if the kernel doesn't support STATX_MNT_ID_UNIQUE
> or AT_HANDLE_MNT_ID_UNIQUE. [Amir Goldstein]
> - v1: <https://lore.kernel.org/all/20240828103706.2393267-1-cyphar@cyphar.com/>
> ---
> src/open_by_handle.c | 132 +++++++++++++++++++++++++++++++++----------
> 1 file changed, 103 insertions(+), 29 deletions(-)
>
> diff --git a/src/open_by_handle.c b/src/open_by_handle.c
> index 0f74ed08b1f0..920ec7d9170b 100644
> --- a/src/open_by_handle.c
> +++ b/src/open_by_handle.c
> @@ -87,6 +87,15 @@ Examples:
> #include <errno.h>
> #include <linux/limits.h>
> #include <libgen.h>
> +#include <stdint.h>
> +#include <stdbool.h>
> +
> +#include <sys/stat.h>
> +#include "statx.h"
> +
> +#ifndef AT_HANDLE_MNT_ID_UNIQUE
> +# define AT_HANDLE_MNT_ID_UNIQUE 0x001
> +#endif
>
> #define MAXFILES 1024
>
> @@ -108,6 +117,7 @@ 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");
> 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 -p <test_dir> - create/delete and try to open by handle also test_dir itself\n");
> @@ -118,6 +128,94 @@ void usage(void)
> exit(EXIT_FAILURE);
> }
>
> +static int do_name_to_handle_at(const char *fname, struct file_handle *fh,
> + int bufsz)
> +{
> + int ret;
> + int mntid_short;
> +
> + static bool skip_mntid, skip_mntid_unique;
> +
> + uint64_t statx_mntid_short = 0, statx_mntid_unique = 0;
> + struct statx statxbuf;
> +
> + /* Get both the short and unique mount id. */
> + if (!skip_mntid) {
> + if (xfstests_statx(AT_FDCWD, fname, 0, STATX_MNT_ID, &statxbuf) < 0) {
> + fprintf(stderr, "%s: statx(STATX_MNT_ID): %m\n", fname);
> + return EXIT_FAILURE;
> + }
> + if (!(statxbuf.stx_mask & STATX_MNT_ID))
> + skip_mntid = true;
> + else
> + statx_mntid_short = statxbuf.stx_mnt_id;
> + }
> +
> + if (!skip_mntid_unique) {
> + if (xfstests_statx(AT_FDCWD, fname, 0, STATX_MNT_ID_UNIQUE, &statxbuf) < 0) {
> + fprintf(stderr, "%s: statx(STATX_MNT_ID_UNIQUE): %m\n", fname);
> + return EXIT_FAILURE;
> + }
> + /*
> + * 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))
> + skip_mntid_unique = true;
> + else
> + statx_mntid_unique = statxbuf.stx_mnt_id;
> + }
> +
> + fh->handle_bytes = bufsz;
> + ret = name_to_handle_at(AT_FDCWD, fname, fh, &mntid_short, 0);
> + if (bufsz < fh->handle_bytes) {
> + /* Query the filesystem required bufsz and the file handle */
> + if (ret != -1 || errno != EOVERFLOW) {
> + fprintf(stderr, "%s: unexpected result from name_to_handle_at: %d (%m)\n", fname, ret);
> + return EXIT_FAILURE;
> + }
> + ret = name_to_handle_at(AT_FDCWD, fname, fh, &mntid_short, 0);
> + }
> + if (ret < 0) {
> + fprintf(stderr, "%s: name_to_handle: %m\n", fname);
> + return EXIT_FAILURE;
> + }
> +
> + if (!skip_mntid) {
> + if (mntid_short != (int) statx_mntid_short) {
> + fprintf(stderr, "%s: name_to_handle_at returned a different mount ID to STATX_MNT_ID: %u != %lu\n", fname, mntid_short, statx_mntid_short);
> + return EXIT_FAILURE;
> + }
> + }
> +
> + if (!skip_mntid_unique) {
> + struct handle dummy_fh;
> + uint64_t mntid_unique = 0;
> +
> + /*
> + * Get the unique mount ID. We don't need to get another copy of the
> + * handle so store it in a dummy struct.
> + */
> + dummy_fh.fh.handle_bytes = fh->handle_bytes;
> + ret = name_to_handle_at(AT_FDCWD, fname, &dummy_fh.fh, (int *) &mntid_unique, AT_HANDLE_MNT_ID_UNIQUE);
> + if (ret < 0) {
> + if (errno != EINVAL) {
> + fprintf(stderr, "%s: name_to_handle_at(AT_HANDLE_MNT_ID_UNIQUE): %m\n", fname);
> + return EXIT_FAILURE;
> + }
> + /* EINVAL means AT_HANDLE_MNT_ID_UNIQUE is not supported */
> + skip_mntid_unique = true;
> + } else {
> + if (mntid_unique != statx_mntid_unique) {
> + fprintf(stderr, "%s: name_to_handle_at(AT_HANDLE_MNT_ID_UNIQUE) returned a different mount ID to STATX_MNT_ID_UNIQUE: %lu != %lu\n", fname, mntid_unique, statx_mntid_unique);
> + return EXIT_FAILURE;
> + }
> + }
> + }
> +
> + return 0;
> +}
> +
> int main(int argc, char **argv)
> {
> int i, c;
> @@ -130,7 +228,7 @@ int main(int argc, char **argv)
> char fname2[PATH_MAX];
> char *test_dir;
> char *mount_dir;
> - int mount_fd, mount_id;
> + int mount_fd;
> char *infile = NULL, *outfile = NULL;
> int in_fd = 0, out_fd = 0;
> int numfiles = 1;
> @@ -305,21 +403,9 @@ int main(int argc, char **argv)
> return EXIT_FAILURE;
> }
> } else {
> - handle[i].fh.handle_bytes = bufsz;
> - ret = name_to_handle_at(AT_FDCWD, fname, &handle[i].fh, &mount_id, 0);
> - if (bufsz < handle[i].fh.handle_bytes) {
> - /* Query the filesystem required bufsz and the file handle */
> - if (ret != -1 || errno != EOVERFLOW) {
> - fprintf(stderr, "Unexpected result from name_to_handle_at(%s)\n", fname);
> - return EXIT_FAILURE;
> - }
> - ret = name_to_handle_at(AT_FDCWD, fname, &handle[i].fh, &mount_id, 0);
> - }
> - if (ret < 0) {
> - strcat(fname, ": name_to_handle");
> - perror(fname);
> + ret = do_name_to_handle_at(fname, &handle[i].fh, bufsz);
> + if (ret)
> return EXIT_FAILURE;
> - }
> }
> if (keepopen) {
> /* Open without close to keep unlinked files around */
> @@ -347,21 +433,9 @@ int main(int argc, char **argv)
> return EXIT_FAILURE;
> }
> } else {
> - dir_handle.fh.handle_bytes = bufsz;
> - ret = name_to_handle_at(AT_FDCWD, test_dir, &dir_handle.fh, &mount_id, 0);
> - if (bufsz < dir_handle.fh.handle_bytes) {
> - /* Query the filesystem required bufsz and the file handle */
> - if (ret != -1 || errno != EOVERFLOW) {
> - fprintf(stderr, "Unexpected result from name_to_handle_at(%s)\n", dname);
> - return EXIT_FAILURE;
> - }
> - ret = name_to_handle_at(AT_FDCWD, test_dir, &dir_handle.fh, &mount_id, 0);
> - }
> - if (ret < 0) {
> - strcat(dname, ": name_to_handle");
> - perror(dname);
> + ret = do_name_to_handle_at(test_dir, &dir_handle.fh, bufsz);
> + if (ret)
> return EXIT_FAILURE;
> - }
> }
> if (out_fd) {
> ret = write(out_fd, (char *)&dir_handle, sizeof(*handle));
> --
> 2.46.0
>
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