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| author | Jeff Layton <jlayton@kernel.org> | 2024-11-11 16:09:56 +0100 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2024-11-12 14:37:12 +0100 |
| commit | ed9d95f691c29748f21bc019de9566b698fdfab7 (patch) | |
| tree | 5b2e64ff56e7ac75f0c4e938918f8d0d3ea2a2e1 | |
| parent | fs: don't let statmount return empty strings (diff) | |
| download | linux-ed9d95f691c29748f21bc019de9566b698fdfab7.tar.xz linux-ed9d95f691c29748f21bc019de9566b698fdfab7.zip | |
fs: add the ability for statmount() to report the fs_subtype
/proc/self/mountinfo prints out the sb->s_subtype after the type. This
is particularly useful for disambiguating FUSE mounts (at least when the
userland driver bothers to set it). Add STATMOUNT_FS_SUBTYPE and claim
one of the __spare2 fields to point to the offset into the str[] array.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ian Kent <raven@themaw.net>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20241111-statmount-v4-2-2eaf35d07a80@kernel.org
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
| -rw-r--r-- | fs/namespace.c | 19 | ||||
| -rw-r--r-- | include/uapi/linux/mount.h | 5 |
2 files changed, 21 insertions, 3 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 23187a414754..dbd89fffd919 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -5004,6 +5004,14 @@ static int statmount_fs_type(struct kstatmount *s, struct seq_file *seq) return 0; } +static void statmount_fs_subtype(struct kstatmount *s, struct seq_file *seq) +{ + struct super_block *sb = s->mnt->mnt_sb; + + if (sb->s_subtype) + seq_puts(seq, sb->s_subtype); +} + static void statmount_mnt_ns_id(struct kstatmount *s, struct mnt_namespace *ns) { s->sm.mask |= STATMOUNT_MNT_NS_ID; @@ -5040,7 +5048,7 @@ static int statmount_mnt_opts(struct kstatmount *s, struct seq_file *seq) static int statmount_string(struct kstatmount *s, u64 flag) { - int ret; + int ret = 0; size_t kbufsize; struct seq_file *seq = &s->seq; struct statmount *sm = &s->sm; @@ -5063,6 +5071,10 @@ static int statmount_string(struct kstatmount *s, u64 flag) sm->mnt_opts = start; ret = statmount_mnt_opts(s, seq); break; + case STATMOUNT_FS_SUBTYPE: + sm->fs_subtype = start; + statmount_fs_subtype(s, seq); + break; default: WARN_ON_ONCE(true); return -EINVAL; @@ -5208,6 +5220,9 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id, if (!err && s->mask & STATMOUNT_MNT_OPTS) err = statmount_string(s, STATMOUNT_MNT_OPTS); + if (!err && s->mask & STATMOUNT_FS_SUBTYPE) + err = statmount_string(s, STATMOUNT_FS_SUBTYPE); + if (!err && s->mask & STATMOUNT_MNT_NS_ID) statmount_mnt_ns_id(s, ns); @@ -5229,7 +5244,7 @@ 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_MNT_OPTS) + STATMOUNT_FS_TYPE | STATMOUNT_MNT_OPTS | STATMOUNT_FS_SUBTYPE) 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 225bc366ffcb..2e939dddf9cb 100644 --- a/include/uapi/linux/mount.h +++ b/include/uapi/linux/mount.h @@ -173,7 +173,9 @@ struct statmount { __u32 mnt_root; /* [str] Root of mount relative to root of fs */ __u32 mnt_point; /* [str] Mountpoint relative to current root */ __u64 mnt_ns_id; /* ID of the mount namespace */ - __u64 __spare2[49]; + __u32 fs_subtype; /* [str] Subtype of fs_type (if any) */ + __u32 __spare1[1]; + __u64 __spare2[48]; char str[]; /* Variable size part containing strings */ }; @@ -207,6 +209,7 @@ struct mnt_id_req { #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 */ +#define STATMOUNT_FS_SUBTYPE 0x00000100U /* Want/got fs_subtype */ /* * Special @mnt_id values that can be passed to listmount |