Introduce MNT_UNION and MS_UNION flags. You need additional patches for
util-linux for that to work.
Signed-off-by: Jan Blunck <jblunck@xxxxxxx>
---
fs/namespace.c | 6 +++++-
include/linux/fs.h | 1 +
include/linux/mount.h | 1 +
3 files changed, 7 insertions(+), 1 deletion(-)
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -437,6 +437,7 @@ static int show_vfsmnt(struct seq_file *
{ MNT_NODIRATIME, ",nodiratime" },
{ MNT_RELATIME, ",relatime" },
{ MNT_NOMNT, ",nomnt" },
+ { MNT_UNION, ",union" },
{ 0, NULL }
};
struct proc_fs_info *fs_infop;
@@ -1558,9 +1559,12 @@ long do_mount(char *dev_name, char *dir_
mnt_flags |= MNT_RELATIME;
if (flags & MS_NOMNT)
mnt_flags |= MNT_NOMNT;
+ if (flags & MS_UNION)
+ mnt_flags |= MNT_UNION;
flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE |
- MS_NOATIME | MS_NODIRATIME | MS_RELATIME | MS_NOMNT);
+ MS_NOATIME | MS_NODIRATIME | MS_RELATIME | MS_NOMNT |
+ MS_UNION );
/* ... and get the mountpoint */
retval = path_lookup(dir_name, LOOKUP_FOLLOW, &nd);
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -114,6 +114,7 @@ extern int dir_notify_enable;
#define MS_REMOUNT 32 /* Alter flags of a mounted FS */
#define MS_MANDLOCK 64 /* Allow mandatory locks on an FS */
#define MS_DIRSYNC 128 /* Directory modifications are synchronous */
+#define MS_UNION 256
#define MS_NOATIME 1024 /* Do not update access times. */
#define MS_NODIRATIME 2048 /* Do not update directory access times */
#define MS_BIND 4096
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -36,6 +36,7 @@ struct mnt_namespace;
#define MNT_SHARED 0x1000 /* if the vfsmount is a shared mount */
#define MNT_UNBINDABLE 0x2000 /* if the vfsmount is a unbindable mount */
#define MNT_PNODE_MASK 0x3000 /* propagation flag mask */
+#define MNT_UNION 0x4000 /* if the vfsmount is a union mount */
struct vfsmount {
struct list_head mnt_hash;
--
-
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