From c72b6b72240508f2ed9308f0d845e3cd35a92759 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Mon, 24 Jun 2024 15:40:50 -0400 Subject: [PATCH 1/3] fs: rename show_mnt_opts -> show_vfsmnt_opts This name is more consistent with what the helper does, which is to just show the vfsmount options. Signed-off-by: Josef Bacik Link: https://lore.kernel.org/r/fb363c62ffbf78a18095d596a19b8412aa991251.1719257716.git.josef@toxicpanda.com Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- fs/proc_namespace.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c index 0a808951b7d3..e133b507ddf3 100644 --- a/fs/proc_namespace.c +++ b/fs/proc_namespace.c @@ -61,7 +61,7 @@ static int show_sb_opts(struct seq_file *m, struct super_block *sb) return security_sb_show_options(m, sb); } -static void show_mnt_opts(struct seq_file *m, struct vfsmount *mnt) +static void show_vfsmnt_opts(struct seq_file *m, struct vfsmount *mnt) { static const struct proc_fs_opts mnt_opts[] = { { MNT_NOSUID, ",nosuid" }, @@ -124,7 +124,7 @@ static int show_vfsmnt(struct seq_file *m, struct vfsmount *mnt) err = show_sb_opts(m, sb); if (err) goto out; - show_mnt_opts(m, mnt); + show_vfsmnt_opts(m, mnt); if (sb->s_op->show_options) err = sb->s_op->show_options(m, mnt_path.dentry); seq_puts(m, " 0 0\n"); @@ -153,7 +153,7 @@ static int show_mountinfo(struct seq_file *m, struct vfsmount *mnt) goto out; seq_puts(m, mnt->mnt_flags & MNT_READONLY ? " ro" : " rw"); - show_mnt_opts(m, mnt); + show_vfsmnt_opts(m, mnt); /* Tagged fields ("foo:X" or "bar") */ if (IS_MNT_SHARED(r)) From f9af549d1fd31487bbbc666b5b158cfc940ccc17 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Mon, 24 Jun 2024 15:40:52 -0400 Subject: [PATCH 2/3] fs: export mount options via statmount() statmount() can export arbitrary strings, so utilize the __spare1 slot for a mnt_opts string pointer, and then support asking for and setting the mount options during statmount(). This calls into the helper for showing mount options, which already uses a seq_file, so fits in nicely with our existing mechanism for exporting strings via statmount(). Signed-off-by: Josef Bacik Link: https://lore.kernel.org/r/3aa6bf8bd5d0a21df9ebd63813af8ab532c18276.1719257716.git.josef@toxicpanda.com Reviewed-by: Jeff Layton [brauner: only call sb->s_op->show_options()] Signed-off-by: Christian Brauner --- fs/namespace.c | 37 ++++++++++++++++++++++++++++++++++++- include/uapi/linux/mount.h | 3 ++- 2 files changed, 38 insertions(+), 2 deletions(-) diff --git a/fs/namespace.c b/fs/namespace.c index a989e89b0a10..c53a0ee748c6 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -4980,6 +4980,34 @@ static void statmount_mnt_ns_id(struct kstatmount *s, struct mnt_namespace *ns) s->sm.mnt_ns_id = ns->seq; } +static int statmount_mnt_opts(struct kstatmount *s, struct seq_file *seq) +{ + struct vfsmount *mnt = s->mnt; + struct super_block *sb = mnt->mnt_sb; + int err; + + if (sb->s_op->show_options) { + size_t start = seq->count; + + err = sb->s_op->show_options(seq, mnt->mnt_root); + if (err) + return err; + + if (unlikely(seq_has_overflowed(seq))) + return -EAGAIN; + + if (seq->count == start) + return 0; + + /* skip leading comma */ + memmove(seq->buf + start, seq->buf + start + 1, + seq->count - start - 1); + seq->count--; + } + + return 0; +} + static int statmount_string(struct kstatmount *s, u64 flag) { int ret; @@ -5000,6 +5028,10 @@ static int statmount_string(struct kstatmount *s, u64 flag) sm->mnt_point = seq->count; ret = statmount_mnt_point(s, seq); break; + case STATMOUNT_MNT_OPTS: + sm->mnt_opts = seq->count; + ret = statmount_mnt_opts(s, seq); + break; default: WARN_ON_ONCE(true); return -EINVAL; @@ -5130,6 +5162,9 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id, if (!err && s->mask & STATMOUNT_MNT_POINT) err = statmount_string(s, STATMOUNT_MNT_POINT); + if (!err && s->mask & STATMOUNT_MNT_OPTS) + err = statmount_string(s, STATMOUNT_MNT_OPTS); + if (!err && s->mask & STATMOUNT_MNT_NS_ID) statmount_mnt_ns_id(s, ns); @@ -5151,7 +5186,7 @@ static inline bool retry_statmount(const long ret, size_t *seq_size) } #define STATMOUNT_STRING_REQ (STATMOUNT_MNT_ROOT | STATMOUNT_MNT_POINT | \ - STATMOUNT_FS_TYPE) + STATMOUNT_FS_TYPE | STATMOUNT_MNT_OPTS) static int prepare_kstatmount(struct kstatmount *ks, struct mnt_id_req *kreq, struct statmount __user *buf, size_t bufsize, diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h index ee1559cd6764..225bc366ffcb 100644 --- a/include/uapi/linux/mount.h +++ b/include/uapi/linux/mount.h @@ -154,7 +154,7 @@ struct mount_attr { */ struct statmount { __u32 size; /* Total size, including strings */ - __u32 __spare1; + __u32 mnt_opts; /* [str] Mount options of the mount */ __u64 mask; /* What results were written */ __u32 sb_dev_major; /* Device ID */ __u32 sb_dev_minor; @@ -206,6 +206,7 @@ struct mnt_id_req { #define STATMOUNT_MNT_POINT 0x00000010U /* Want/got mnt_point */ #define STATMOUNT_FS_TYPE 0x00000020U /* Want/got fs_type */ #define STATMOUNT_MNT_NS_ID 0x00000040U /* Want/got mnt_ns_id */ +#define STATMOUNT_MNT_OPTS 0x00000080U /* Want/got mnt_opts */ /* * Special @mnt_id values that can be passed to listmount From e2f718e25537d3567ababbe4276306efd3f23f47 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Mon, 24 Jun 2024 15:40:53 -0400 Subject: [PATCH 3/3] sefltests: extend the statmount test for mount options Now that we support exporting mount options, via statmount(), add a test to validate that it works. Signed-off-by: Josef Bacik Link: https://lore.kernel.org/r/cabe09f0933d9c522da6e7b6cc160254f4f6c3b9.1719257716.git.josef@toxicpanda.com Reviewed-by: Jeff Layton [brauner: simplify and fix] Signed-off-by: Christian Brauner --- .../filesystems/statmount/statmount_test.c | 91 ++++++++++++++++++- 1 file changed, 90 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/filesystems/statmount/statmount_test.c b/tools/testing/selftests/filesystems/statmount/statmount_test.c index 4f7023c2de77..ece005864863 100644 --- a/tools/testing/selftests/filesystems/statmount/statmount_test.c +++ b/tools/testing/selftests/filesystems/statmount/statmount_test.c @@ -107,6 +107,7 @@ static char root_mntpoint[] = "/tmp/statmount_test_root.XXXXXX"; static int orig_root; static uint64_t root_id, parent_id; static uint32_t old_root_id, old_parent_id; +static FILE *f_mountinfo; static void cleanup_namespace(void) { @@ -134,6 +135,11 @@ static void setup_namespace(void) sprintf(buf, "0 %d 1", gid); write_file("/proc/self/gid_map", buf); + f_mountinfo = fopen("/proc/self/mountinfo", "re"); + if (!f_mountinfo) + ksft_exit_fail_msg("failed to open mountinfo: %s\n", + strerror(errno)); + ret = mount("", "/", NULL, MS_REC|MS_PRIVATE, NULL); if (ret == -1) ksft_exit_fail_msg("making mount tree private: %s\n", @@ -435,6 +441,88 @@ static void test_statmount_fs_type(void) free(sm); } +static void test_statmount_mnt_opts(void) +{ + struct statmount *sm; + const char *statmount_opts; + char *line = NULL; + size_t len = 0; + + sm = statmount_alloc(root_id, STATMOUNT_MNT_BASIC | STATMOUNT_MNT_OPTS, + 0); + if (!sm) { + ksft_test_result_fail("statmount mnt opts: %s\n", + strerror(errno)); + return; + } + + while (getline(&line, &len, f_mountinfo) != -1) { + int i; + char *p, *p2; + unsigned int old_mnt_id; + + old_mnt_id = atoi(line); + if (old_mnt_id != sm->mnt_id_old) + continue; + + for (p = line, i = 0; p && i < 5; i++) + p = strchr(p + 1, ' '); + if (!p) + continue; + + p2 = strchr(p + 1, ' '); + if (!p2) + continue; + *p2 = '\0'; + p = strchr(p2 + 1, '-'); + if (!p) + continue; + for (p++, i = 0; p && i < 2; i++) + p = strchr(p + 1, ' '); + if (!p) + continue; + p++; + + /* skip generic superblock options */ + if (strncmp(p, "ro", 2) == 0) + p += 2; + else if (strncmp(p, "rw", 2) == 0) + p += 2; + if (*p == ',') + p++; + if (strncmp(p, "sync", 4) == 0) + p += 4; + if (*p == ',') + p++; + if (strncmp(p, "dirsync", 7) == 0) + p += 7; + if (*p == ',') + p++; + if (strncmp(p, "lazytime", 8) == 0) + p += 8; + if (*p == ',') + p++; + p2 = strrchr(p, '\n'); + if (p2) + *p2 = '\0'; + + statmount_opts = sm->str + sm->mnt_opts; + if (strcmp(statmount_opts, p) != 0) + ksft_test_result_fail( + "unexpected mount options: '%s' != '%s'\n", + statmount_opts, p); + else + ksft_test_result_pass("statmount mount options\n"); + free(sm); + free(line); + return; + } + + ksft_test_result_fail("didnt't find mount entry\n"); + free(sm); + free(line); +} + static void test_statmount_string(uint64_t mask, size_t off, const char *name) { struct statmount *sm; @@ -561,7 +649,7 @@ int main(void) setup_namespace(); - ksft_set_plan(14); + ksft_set_plan(15); test_listmount_empty_root(); test_statmount_zero_mask(); test_statmount_mnt_basic(); @@ -569,6 +657,7 @@ int main(void) test_statmount_mnt_root(); test_statmount_mnt_point(); test_statmount_fs_type(); + test_statmount_mnt_opts(); test_statmount_string(STATMOUNT_MNT_ROOT, str_off(mnt_root), "mount root"); test_statmount_string(STATMOUNT_MNT_POINT, str_off(mnt_point), "mount point"); test_statmount_string(STATMOUNT_FS_TYPE, str_off(fs_type), "fs type");