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@xxxxxxxxxxxxxx>
---
fs/namespace.c | 7 +++++++
include/uapi/linux/mount.h | 3 ++-
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index 6d44537fd78c..2a6a8cbf5d0a 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -5003,6 +5003,10 @@ 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 = show_mount_opts(seq, s->mnt);
+ break;
default:
WARN_ON_ONCE(true);
return -EINVAL;
@@ -5079,6 +5083,9 @@ static int do_statmount(struct kstatmount *s)
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);
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
--
2.43.0
