Re: [PATCH xfstests v2 2/2] open_by_handle: add tests for u64 mount ID

[Amir Goldstein <amir73il@gmail.com>]

On Mon, Sep 2, 2024 at 6:46 PM Aleksa Sarai <cyphar@cyphar.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.
>
> Link: https://lore.kernel.org/all/20240828-exportfs-u64-mount-id-v3-0-10c2c4c16708@cyphar.com/
> Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
> ---
> 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/>

Looks good.

You may add:

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

It'd be nice to get a verification that this is indeed tested on the latest
upstream and does not regress the tests that run the open_by_handle program.

Thanks,
Amir.

>
>  src/open_by_handle.c | 128 +++++++++++++++++++++++++++++++++----------
>  1 file changed, 99 insertions(+), 29 deletions(-)
>
> diff --git a/src/open_by_handle.c b/src/open_by_handle.c
> index d9c802ca9bd1..0ad591da632e 100644
> --- a/src/open_by_handle.c
> +++ b/src/open_by_handle.c
> @@ -86,10 +86,16 @@ 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
>
>  struct handle {
> @@ -120,6 +126,94 @@ void usage(void)
>         exit(EXIT_FAILURE);
>  }
>
> +int do_name_to_handle_at(const char *fname, struct file_handle *fh, int bufsz)
> +{
> +       int ret;
> +       int mntid_short;
> +
> +       static bool 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 (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)) {
> +               fprintf(stderr, "%s: no STATX_MNT_ID in stx_mask\n", fname);
> +               return EXIT_FAILURE;
> +       }
> +       statx_mntid_short = statxbuf.stx_mnt_id;
> +
> +       if (!skip_mntid_unique) {
> +               if (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 ((skip_mntid_unique |= !(statxbuf.stx_mask & STATX_MNT_ID_UNIQUE)))
> +                       printf("statx(STATX_MNT_ID_UNIQUE) not supported by running kernel -- skipping unique mount ID test\n");
> +               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 (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 && statx_mntid_unique != 0) {
> +               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, so skip
> +                        * the check in that case.
> +                        */
> +                       printf("name_to_handle_at(AT_HANDLE_MNT_ID_UNIQUE) not supported by running kernel -- skipping unique mount ID test\n");
> +                       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;
> @@ -132,7 +226,7 @@ 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;
> @@ -307,21 +401,9 @@ 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 < 0)
>                                 return EXIT_FAILURE;
> -                       }
>                 }
>                 if (keepopen) {
>                         /* Open without close to keep unlinked files around */
> @@ -349,21 +431,9 @@ 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 < 0)
>                                 return EXIT_FAILURE;
> -                       }
>                 }
>                 if (out_fd) {
>                         ret = write(out_fd, (char *)&dir_handle, sizeof(*handle));
> --
> 2.46.0
>