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@xxxxxxxxxx/ Signed-off-by: Aleksa Sarai <cyphar@xxxxxxxxxx> --- 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@xxxxxxxxxx/> 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
