[patch 1/5] union-directory: Introduce MNT_UNION and MS_UNION flags

From: Miklos Szeredi
Date: Thu May 21 2009 - 05:24:33 EST


From: Jan Blunck <jblunck@xxxxxxx>

Add per mountpoint flag for Union Mount support. You need additional patches
to util-linux for that to work (ftp.suse.com/pub/people/jblunck/union-mount).

Signed-off-by: Jan Blunck <jblunck@xxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
---
fs/namespace.c | 5 ++++-
include/linux/fs.h | 1 +
include/linux/mount.h | 1 +
3 files changed, 6 insertions(+), 1 deletion(-)

Index: linux-2.6/fs/namespace.c
===================================================================
--- linux-2.6.orig/fs/namespace.c 2009-05-20 15:05:15.000000000 +0200
+++ linux-2.6/fs/namespace.c 2009-05-20 15:07:46.000000000 +0200
@@ -796,6 +796,7 @@ static void show_mnt_opts(struct seq_fil
{ MNT_NODIRATIME, ",nodiratime" },
{ MNT_RELATIME, ",relatime" },
{ MNT_STRICTATIME, ",strictatime" },
+ { MNT_UNION, ",union" },
{ 0, NULL }
};
const struct proc_fs_info *fs_infop;
@@ -1952,10 +1953,12 @@ long do_mount(char *dev_name, char *dir_
mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME);
if (flags & MS_RDONLY)
mnt_flags |= MNT_READONLY;
+ if (flags & MS_UNION)
+ mnt_flags |= MNT_UNION;

flags &= ~(MS_NOSUID | MS_NOEXEC | MS_NODEV | MS_ACTIVE |
MS_NOATIME | MS_NODIRATIME | MS_RELATIME| MS_KERNMOUNT |
- MS_STRICTATIME);
+ MS_STRICTATIME | MS_UNION);

/* ... and get the mountpoint */
retval = kern_path(dir_name, LOOKUP_FOLLOW, &path);
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h 2009-05-20 15:05:15.000000000 +0200
+++ linux-2.6/include/linux/fs.h 2009-05-20 15:07:46.000000000 +0200
@@ -188,6 +188,7 @@ struct inodes_stat_t {
#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
Index: linux-2.6/include/linux/mount.h
===================================================================
--- linux-2.6.orig/include/linux/mount.h 2009-05-20 15:05:15.000000000 +0200
+++ linux-2.6/include/linux/mount.h 2009-05-20 15:07:46.000000000 +0200
@@ -35,6 +35,7 @@ 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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