[PATCH] introduce slave mounts

[mv-sheeva.git] / fs / pnode.c

diff --git a/fs/pnode.c b/fs/pnode.c
index 7bc942d047cd299df0e76282664ba1d052c81c1b..f73eba24f1d17c24140b849e162b3e7f5a79e446 100644 (file)
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -17,13 +17,61 @@ static inline struct vfsmount *next_peer(struct vfsmount *p)
        return list_entry(p->mnt_share.next, struct vfsmount, mnt_share);
 }
 
+static int do_make_slave(struct vfsmount *mnt)
+{
+       struct vfsmount *peer_mnt = mnt, *master = mnt->mnt_master;
+       struct vfsmount *slave_mnt;
+
+       /*
+        * slave 'mnt' to a peer mount that has the
+        * same root dentry. If none is available than
+        * slave it to anything that is available.
+        */
+       while ((peer_mnt = next_peer(peer_mnt)) != mnt &&
+              peer_mnt->mnt_root != mnt->mnt_root) ;
+
+       if (peer_mnt == mnt) {
+               peer_mnt = next_peer(mnt);
+               if (peer_mnt == mnt)
+                       peer_mnt = NULL;
+       }
+       list_del_init(&mnt->mnt_share);
+
+       if (peer_mnt)
+               master = peer_mnt;
+
+       if (master) {
+               list_for_each_entry(slave_mnt, &mnt->mnt_slave_list, mnt_slave)
+                       slave_mnt->mnt_master = master;
+               list_del(&mnt->mnt_slave);
+               list_add(&mnt->mnt_slave, &master->mnt_slave_list);
+               list_splice(&mnt->mnt_slave_list, master->mnt_slave_list.prev);
+               INIT_LIST_HEAD(&mnt->mnt_slave_list);
+       } else {
+               struct list_head *p = &mnt->mnt_slave_list;
+               while (!list_empty(p)) {
+                        slave_mnt = list_entry(p->next,
+                                       struct vfsmount, mnt_slave);
+                       list_del_init(&slave_mnt->mnt_slave);
+                       slave_mnt->mnt_master = NULL;
+               }
+       }
+       mnt->mnt_master = master;
+       CLEAR_MNT_SHARED(mnt);
+       INIT_LIST_HEAD(&mnt->mnt_slave_list);
+       return 0;
+}
+
 void change_mnt_propagation(struct vfsmount *mnt, int type)
 {
        if (type == MS_SHARED) {
                set_mnt_shared(mnt);
-       } else {
-               list_del_init(&mnt->mnt_share);
-               mnt->mnt_flags &= ~MNT_PNODE_MASK;
+               return;
+       }
+       do_make_slave(mnt);
+       if (type != MS_SLAVE) {
+               list_del_init(&mnt->mnt_slave);
+               mnt->mnt_master = NULL;
        }
 }