/proc/self/mountinfo displays the devicename for the mount, but
statmount() doesn't yet have a way to return it. Add a new
STATMOUNT_MNT_DEVNAME flag, claim the 32-bit __spare1 field to hold the
offset into the str[] array. STATMOUNT_MNT_DEVNAME will only be set in
the return mask if there is a device string.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/namespace.c | 25 ++++++++++++++++++++++++-
include/uapi/linux/mount.h | 3 ++-
2 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/fs/namespace.c b/fs/namespace.c
index 52ab892088f08ad71647eff533dd6f3025bbae03..d4ed2cb5de12c86b4da58626441e072fc109b2ff 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -5014,6 +5014,19 @@ static void statmount_fs_subtype(struct kstatmount *s, struct seq_file *seq)
seq_puts(seq, sb->s_subtype);
}
+static int statmount_mnt_devname(struct kstatmount *s, struct seq_file *seq)
+{
+ struct super_block *sb = s->mnt->mnt_sb;
+ struct mount *r = real_mount(s->mnt);
+
+ if (sb->s_op->show_devname)
+ return sb->s_op->show_devname(seq, s->mnt->mnt_root);
+
+ if (r->mnt_devname)
+ seq_puts(seq, r->mnt_devname);
+ return 0;
+}
+
static void statmount_mnt_ns_id(struct kstatmount *s, struct mnt_namespace *ns)
{
s->sm.mask |= STATMOUNT_MNT_NS_ID;
@@ -5078,6 +5091,12 @@ static int statmount_string(struct kstatmount *s, u64 flag)
if (seq->count == sm->fs_subtype)
return 0;
break;
+ case STATMOUNT_MNT_DEVNAME:
+ sm->mnt_devname = seq->count;
+ ret = statmount_mnt_devname(s, seq);
+ if (seq->count == sm->mnt_devname)
+ return ret;
+ break;
default:
WARN_ON_ONCE(true);
return -EINVAL;
@@ -5220,6 +5239,9 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id,
if (!err && s->mask & STATMOUNT_FS_SUBTYPE)
err = statmount_string(s, STATMOUNT_FS_SUBTYPE);
+ if (!err && s->mask & STATMOUNT_MNT_DEVNAME)
+ err = statmount_string(s, STATMOUNT_MNT_DEVNAME);
+
if (!err && s->mask & STATMOUNT_MNT_NS_ID)
statmount_mnt_ns_id(s, ns);
@@ -5241,7 +5263,8 @@ 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_SUBTYPE)
+ STATMOUNT_FS_TYPE | STATMOUNT_MNT_OPTS | \
+ STATMOUNT_FS_SUBTYPE | STATMOUNT_MNT_DEVNAME)
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 fa206fb56b3b25cf80f7d430e1b6bab19c3220e4..0f9ea2748f6376b5e71ba969598fc5b641a2c77f 100644
--- a/include/uapi/linux/mount.h
+++ b/include/uapi/linux/mount.h
@@ -174,7 +174,7 @@ struct statmount {
__u32 mnt_point; /* [str] Mountpoint relative to current root */
__u64 mnt_ns_id; /* ID of the mount namespace */
__u32 fs_subtype; /* [str] Subtype of fs_type (if any) */
- __u32 __spare1[1];
+ __u32 mnt_devname; /* [str] Device string for the mount */
__u64 __spare2[48];
char str[]; /* Variable size part containing strings */
};
@@ -210,6 +210,7 @@ struct mnt_id_req {
#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 subtype */
+#define STATMOUNT_MNT_DEVNAME 0x00000200U /* Want/got devname */
/*
* Special @mnt_id values that can be passed to listmount
--
2.47.0
