vfs: now it can be done - make mnt_parent point to struct mount

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

5 files changed, 53 insertions, 50 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index eef2d5472f9c..98b48753f77b 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2452,6 +2452,7 @@ static int prepend_path(const struct path *path,
 {
         struct dentry *dentry = path->dentry;
         struct vfsmount *vfsmnt = path->mnt;
+        struct mount *mnt = real_mount(vfsmnt);
         bool slash = false;
         int error = 0;
 
@@ -2460,12 +2461,12 @@ static int prepend_path(const struct path *path,
                 struct dentry * parent;
 
                 if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
-                        struct mount *mnt = real_mount(vfsmnt);
                         /* Global root? */
                         if (!mnt_has_parent(mnt))
                                 goto global_root;
-                        dentry = vfsmnt->mnt_mountpoint;
-                        vfsmnt = mnt->mnt_parent;
+                        dentry = mnt->mnt.mnt_mountpoint;
+                        mnt = mnt->mnt_parent;
+                        vfsmnt = &mnt->mnt;
                         continue;
                 }
                 parent = dentry->d_parent;
diff --git a/fs/mount.h b/fs/mount.h
index 5126c0861102..201dd616e6c4 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -2,7 +2,7 @@
 
 struct mount {
         struct list_head mnt_hash;
-        struct vfsmount *mnt_parent;
+        struct mount *mnt_parent;
         struct vfsmount mnt;
 };
 
@@ -13,7 +13,7 @@ static inline struct mount *real_mount(struct vfsmount *mnt)
 
 static inline int mnt_has_parent(struct mount *mnt)
 {
-        return &mnt->mnt != mnt->mnt_parent;
+        return mnt != mnt->mnt_parent;
 }
 
 extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *, int);
diff --git a/fs/namei.c b/fs/namei.c
index 89248bf1b906..2e9110a37c0e 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -677,36 +677,38 @@ follow_link(struct path *link, struct nameidata *nd, void **p)
 
 static int follow_up_rcu(struct path *path)
 {
-        struct vfsmount *parent;
+        struct mount *mnt = real_mount(path->mnt);
+        struct mount *parent;
         struct dentry *mountpoint;
 
-        parent = real_mount(path->mnt)->mnt_parent;
-        if (parent == path->mnt)
+        parent = mnt->mnt_parent;
+        if (&parent->mnt == path->mnt)
                 return 0;
-        mountpoint = path->mnt->mnt_mountpoint;
+        mountpoint = mnt->mnt.mnt_mountpoint;
         path->dentry = mountpoint;
-        path->mnt = parent;
+        path->mnt = &parent->mnt;
         return 1;
 }
 
 int follow_up(struct path *path)
 {
-        struct vfsmount *parent;
+        struct mount *mnt = real_mount(path->mnt);
+        struct mount *parent;
         struct dentry *mountpoint;
 
         br_read_lock(vfsmount_lock);
-        parent = real_mount(path->mnt)->mnt_parent;
-        if (parent == path->mnt) {
+        parent = mnt->mnt_parent;
+        if (&parent->mnt == path->mnt) {
                 br_read_unlock(vfsmount_lock);
                 return 0;
         }
-        mntget(parent);
-        mountpoint = dget(path->mnt->mnt_mountpoint);
+        mntget(&parent->mnt);
+        mountpoint = dget(mnt->mnt.mnt_mountpoint);
         br_read_unlock(vfsmount_lock);
         dput(path->dentry);
         path->dentry = mountpoint;
         mntput(path->mnt);
-        path->mnt = parent;
+        path->mnt = &parent->mnt;
         return 1;
 }
 
diff --git a/fs/namespace.c b/fs/namespace.c
index c6384bc39db1..5e700c6df579 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -476,7 +476,7 @@ struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry,
                 if (tmp == head)
                         break;
                 p = list_entry(tmp, struct mount, mnt_hash);
-                if (p->mnt_parent == mnt && p->mnt.mnt_mountpoint == dentry) {
+                if (&p->mnt_parent->mnt == mnt && p->mnt.mnt_mountpoint == dentry) {
                         found = p;
                         break;
                 }
@@ -558,8 +558,8 @@ static void dentry_reset_mounted(struct dentry *dentry)
 static void detach_mnt(struct mount *mnt, struct path *old_path)
 {
         old_path->dentry = mnt->mnt.mnt_mountpoint;
-        old_path->mnt = mnt->mnt_parent;
-        mnt->mnt_parent = &mnt->mnt;
+        old_path->mnt = &mnt->mnt_parent->mnt;
+        mnt->mnt_parent = mnt;
         mnt->mnt.mnt_mountpoint = mnt->mnt.mnt_root;
         list_del_init(&mnt->mnt.mnt_child);
         list_del_init(&mnt->mnt_hash);
@@ -572,7 +572,7 @@ static void detach_mnt(struct mount *mnt, struct path *old_path)
 void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
                         struct mount *child_mnt)
 {
-        child_mnt->mnt_parent = mntget(mnt);
+        child_mnt->mnt_parent = real_mount(mntget(mnt));
         child_mnt->mnt.mnt_mountpoint = dget(dentry);
         spin_lock(&dentry->d_lock);
         dentry->d_flags |= DCACHE_MOUNTED;
@@ -610,12 +610,12 @@ static inline void __mnt_make_shortterm(struct vfsmount *mnt)
  */
 static void commit_tree(struct mount *mnt)
 {
-        struct vfsmount *parent = mnt->mnt_parent;
+        struct mount *parent = mnt->mnt_parent;
         struct vfsmount *m;
         LIST_HEAD(head);
-        struct mnt_namespace *n = parent->mnt_ns;
+        struct mnt_namespace *n = parent->mnt.mnt_ns;
 
-        BUG_ON(parent == &mnt->mnt);
+        BUG_ON(parent == mnt);
 
         list_add_tail(&head, &mnt->mnt.mnt_list);
         list_for_each_entry(m, &head, mnt_list) {
@@ -626,8 +626,8 @@ static void commit_tree(struct mount *mnt)
         list_splice(&head, n->list.prev);
 
         list_add_tail(&mnt->mnt_hash, mount_hashtable +
-                                hash(parent, mnt->mnt.mnt_mountpoint));
-        list_add_tail(&mnt->mnt.mnt_child, &parent->mnt_mounts);
+                                hash(&parent->mnt, mnt->mnt.mnt_mountpoint));
+        list_add_tail(&mnt->mnt.mnt_child, &parent->mnt.mnt_mounts);
         touch_mnt_namespace(n);
 }
 
@@ -639,9 +639,9 @@ static struct mount *next_mnt(struct mount *p, struct vfsmount *root)
                         if (&p->mnt == root)
                                 return NULL;
                         next = p->mnt.mnt_child.next;
-                        if (next != &p->mnt_parent->mnt_mounts)
+                        if (next != &p->mnt_parent->mnt.mnt_mounts)
                                 break;
-                        p = real_mount(p->mnt_parent);
+                        p = p->mnt_parent;
                 }
         }
         return list_entry(next, struct mount, mnt.mnt_child);
@@ -682,7 +682,7 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void
         mnt->mnt.mnt_root = root;
         mnt->mnt.mnt_sb = root->d_sb;
         mnt->mnt.mnt_mountpoint = mnt->mnt.mnt_root;
-        mnt->mnt_parent = &mnt->mnt;
+        mnt->mnt_parent = mnt;
         return &mnt->mnt;
 }
 EXPORT_SYMBOL_GPL(vfs_kern_mount);
@@ -710,7 +710,7 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
                 mnt->mnt.mnt_sb = sb;
                 mnt->mnt.mnt_root = dget(root);
                 mnt->mnt.mnt_mountpoint = mnt->mnt.mnt_root;
-                mnt->mnt_parent = &mnt->mnt;
+                mnt->mnt_parent = mnt;
 
                 if (flag & CL_SLAVE) {
                         list_add(&mnt->mnt.mnt_slave, &old->mnt.mnt_slave_list);
@@ -1027,7 +1027,7 @@ static int show_mountinfo(struct seq_file *m, void *v)
         struct path root = p->root;
         int err = 0;
 
-        seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, r->mnt_parent->mnt_id,
+        seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, r->mnt_parent->mnt.mnt_id,
                    MAJOR(sb->s_dev), MINOR(sb->s_dev));
         if (sb->s_op->show_path)
                 err = sb->s_op->show_path(m, mnt);
@@ -1202,9 +1202,9 @@ void release_mounts(struct list_head *head)
 
                         br_write_lock(vfsmount_lock);
                         dentry = mnt->mnt.mnt_mountpoint;
-                        m = mnt->mnt_parent;
+                        m = &mnt->mnt_parent->mnt;
                         mnt->mnt.mnt_mountpoint = mnt->mnt.mnt_root;
-                        mnt->mnt_parent = &mnt->mnt;
+                        mnt->mnt_parent = mnt;
                         m->mnt_ghosts--;
                         br_write_unlock(vfsmount_lock);
                         dput(dentry);
@@ -1237,7 +1237,7 @@ void umount_tree(struct mount *mnt, int propagate, struct list_head *kill)
                 __mnt_make_shortterm(&p->mnt);
                 list_del_init(&p->mnt.mnt_child);
                 if (mnt_has_parent(p)) {
-                        p->mnt_parent->mnt_ghosts++;
+                        p->mnt_parent->mnt.mnt_ghosts++;
                         dentry_reset_mounted(p->mnt.mnt_mountpoint);
                 }
                 change_mnt_propagation(p, MS_PRIVATE);
@@ -1435,9 +1435,9 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry,
                                 s = skip_mnt_tree(s);
                                 continue;
                         }
-                        while (p != real_mount(s->mnt_parent)) {
-                                p = real_mount(p->mnt_parent);
-                                q = real_mount(q->mnt_parent);
+                        while (p != s->mnt_parent) {
+                                p = p->mnt_parent;
+                                q = q->mnt_parent;
                         }
                         p = s;
                         path.mnt = &q->mnt;
@@ -1899,7 +1899,7 @@ static int do_move_mount(struct path *path, char *old_name)
         /*
          * Don't move a mount residing in a shared parent.
          */
-        if (IS_MNT_SHARED(old->mnt_parent))
+        if (IS_MNT_SHARED(&old->mnt_parent->mnt))
                 goto out1;
         /*
          * Don't move a mount tree containing unbindable mounts to a destination
@@ -1909,7 +1909,7 @@ static int do_move_mount(struct path *path, char *old_name)
             tree_contains_unbindable(old))
                 goto out1;
         err = -ELOOP;
-        for (p = real_mount(path->mnt); mnt_has_parent(p); p = real_mount(p->mnt_parent))
+        for (p = real_mount(path->mnt); mnt_has_parent(p); p = p->mnt_parent)
                 if (p == old)
                         goto out1;
 
@@ -2159,7 +2159,7 @@ resume:
          */
         if (this_parent != parent) {
                 next = this_parent->mnt.mnt_child.next;
-                this_parent = real_mount(this_parent->mnt_parent);
+                this_parent = this_parent->mnt_parent;
                 goto resume;
         }
         return found;
@@ -2565,7 +2565,7 @@ bool is_path_reachable(struct mount *mnt, struct dentry *dentry,
 {
         while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) {
                 dentry = mnt->mnt.mnt_mountpoint;
-                mnt = real_mount(mnt->mnt_parent);
+                mnt = mnt->mnt_parent;
         }
         return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry);
 }
@@ -2636,8 +2636,8 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
         new_mnt = real_mount(new.mnt);
         root_mnt = real_mount(root.mnt);
         if (IS_MNT_SHARED(old.mnt) ||
-                IS_MNT_SHARED(new_mnt->mnt_parent) ||
-                IS_MNT_SHARED(root_mnt->mnt_parent))
+                IS_MNT_SHARED(&new_mnt->mnt_parent->mnt) ||
+                IS_MNT_SHARED(&root_mnt->mnt_parent->mnt))
                 goto out4;
         if (!check_mnt(root.mnt) || !check_mnt(new.mnt))
                 goto out4;
diff --git a/fs/pnode.c b/fs/pnode.c
index 2ff4dfa018e1..7fddc671f729 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -292,10 +292,10 @@ int propagate_mount_busy(struct mount *mnt, int refcnt)
 {
         struct vfsmount *m;
         struct mount *child;
-        struct vfsmount *parent = mnt->mnt_parent;
+        struct mount *parent = mnt->mnt_parent;
         int ret = 0;
 
-        if (&mnt->mnt == parent)
+        if (mnt == parent)
                 return do_refcount_check(mnt, refcnt);
 
         /*
@@ -306,8 +306,8 @@ int propagate_mount_busy(struct mount *mnt, int refcnt)
         if (!list_empty(&mnt->mnt.mnt_mounts) || do_refcount_check(mnt, refcnt))
                 return 1;
 
-        for (m = propagation_next(parent, parent); m;
-                        m = propagation_next(m, parent)) {
+        for (m = propagation_next(&parent->mnt, &parent->mnt); m;
+                        m = propagation_next(m, &parent->mnt)) {
                 child = __lookup_mnt(m, mnt->mnt.mnt_mountpoint, 0);
                 if (child && list_empty(&child->mnt.mnt_mounts) &&
                     (ret = do_refcount_check(child, 1)))
@@ -322,13 +322,13 @@ int propagate_mount_busy(struct mount *mnt, int refcnt)
  */
 static void __propagate_umount(struct mount *mnt)
 {
-        struct vfsmount *parent = mnt->mnt_parent;
+        struct mount *parent = mnt->mnt_parent;
         struct vfsmount *m;
 
-        BUG_ON(parent == &mnt->mnt);
+        BUG_ON(parent == mnt);
 
-        for (m = propagation_next(parent, parent); m;
-                        m = propagation_next(m, parent)) {
+        for (m = propagation_next(&parent->mnt, &parent->mnt); m;
+                        m = propagation_next(m, &parent->mnt)) {
 
                 struct mount *child = __lookup_mnt(m,
                                         mnt->mnt.mnt_mountpoint, 0);