diff options
| author | Josef Bacik <josef@toxicpanda.com> | 2024-06-24 15:40:52 -0400 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2024-06-28 14:36:43 +0200 |
| commit | f9af549d1fd31487bbbc666b5b158cfc940ccc17 (patch) | |
| tree | 11c62f7a1e9239c58bd0ae67737d5d79280b479e | |
| parent | c72b6b72240508f2ed9308f0d845e3cd35a92759 (diff) | |
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 <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/3aa6bf8bd5d0a21df9ebd63813af8ab532c18276.1719257716.git.josef@toxicpanda.com
Reviewed-by: Jeff Layton <jlayton@kernel.org>
[brauner: only call sb->s_op->show_options()]
Signed-off-by: Christian Brauner <brauner@kernel.org>
| -rw-r--r-- | fs/namespace.c | 37 | ||||
| -rw-r--r-- | 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 |