[PATCH] introduce shared mounts

This creates shared mounts.  A shared mount when bind-mounted to some
mountpoint, propagates mount/umount events to each other.  All the
shared mounts that propagate events to each other belong to the same
peer-group.

Signed-off-by: Ram Pai <linuxram@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 12 insertions, 1 deletions

diff --git a/fs/pnode.c b/fs/pnode.c
index aaa0dffda12a..1e22165ea41f 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -11,7 +11,18 @@
 #include <linux/fs.h>
 #include "pnode.h"
 
+/* return the next shared peer mount of @p */
+static inline struct vfsmount *next_peer(struct vfsmount *p)
+{
+        return list_entry(p->mnt_share.next, struct vfsmount, mnt_share);
+}
+
 void change_mnt_propagation(struct vfsmount *mnt, int type)
 {
-        mnt->mnt_flags &= ~MNT_PNODE_MASK;
+        if (type == MS_SHARED) {
+                mnt->mnt_flags |= MNT_SHARED;
+        } else {
+                list_del_init(&mnt->mnt_share);
+                mnt->mnt_flags &= ~MNT_PNODE_MASK;
+        }
 }