vfs: spread struct mount - attach_mnt/detach_mnt
Al Viro [Fri, 25 Nov 2011 00:41:16 +0000 (19:41 -0500)]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namespace.c

index 7226dc5..444557e 100644 (file)
@@ -556,14 +556,14 @@ static void dentry_reset_mounted(struct dentry *dentry)
 /*
  * vfsmount lock must be held for write
  */
-static void detach_mnt(struct vfsmount *mnt, struct path *old_path)
-{
-       old_path->dentry = mnt->mnt_mountpoint;
-       old_path->mnt = mnt->mnt_parent;
-       mnt->mnt_parent = mnt;
-       mnt->mnt_mountpoint = mnt->mnt_root;
-       list_del_init(&mnt->mnt_child);
-       list_del_init(&mnt->mnt_hash);
+static void detach_mnt(struct mount *mnt, struct path *old_path)
+{
+       old_path->dentry = mnt->mnt.mnt_mountpoint;
+       old_path->mnt = mnt->mnt.mnt_parent;
+       mnt->mnt.mnt_parent = &mnt->mnt;
+       mnt->mnt.mnt_mountpoint = mnt->mnt.mnt_root;
+       list_del_init(&mnt->mnt.mnt_child);
+       list_del_init(&mnt->mnt.mnt_hash);
        dentry_reset_mounted(old_path->dentry);
 }
 
@@ -583,12 +583,12 @@ void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
 /*
  * vfsmount lock must be held for write
  */
-static void attach_mnt(struct vfsmount *mnt, struct path *path)
+static void attach_mnt(struct mount *mnt, struct path *path)
 {
-       mnt_set_mountpoint(path->mnt, path->dentry, mnt);
-       list_add_tail(&mnt->mnt_hash, mount_hashtable +
+       mnt_set_mountpoint(path->mnt, path->dentry, &mnt->mnt);
+       list_add_tail(&mnt->mnt.mnt_hash, mount_hashtable +
                        hash(path->mnt, path->dentry));
-       list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts);
+       list_add_tail(&mnt->mnt.mnt_child, &path->mnt->mnt_mounts);
 }
 
 static inline void __mnt_make_longterm(struct vfsmount *mnt)
@@ -1446,7 +1446,7 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry,
                                goto Enomem;
                        br_write_lock(vfsmount_lock);
                        list_add_tail(&q->mnt_list, &res->mnt_list);
-                       attach_mnt(q, &path);
+                       attach_mnt(real_mount(q), &path);
                        br_write_unlock(vfsmount_lock);
                }
        }
@@ -1612,8 +1612,8 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt,
                        set_mnt_shared(&p->mnt);
        }
        if (parent_path) {
-               detach_mnt(source_mnt, parent_path);
-               attach_mnt(source_mnt, path);
+               detach_mnt(real_mount(source_mnt), parent_path);
+               attach_mnt(real_mount(source_mnt), path);
                touch_mnt_namespace(parent_path->mnt->mnt_ns);
        } else {
                mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
@@ -2600,6 +2600,7 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
                const char __user *, put_old)
 {
        struct path new, old, parent_path, root_parent, root;
+       struct mount *new_mnt, *root_mnt;
        int error;
 
        if (!capable(CAP_SYS_ADMIN))
@@ -2623,6 +2624,8 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
                goto out3;
 
        error = -EINVAL;
+       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))
@@ -2651,12 +2654,12 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
        if (!is_path_reachable(old.mnt, old.dentry, &new))
                goto out4;
        br_write_lock(vfsmount_lock);
-       detach_mnt(new.mnt, &parent_path);
-       detach_mnt(root.mnt, &root_parent);
+       detach_mnt(new_mnt, &parent_path);
+       detach_mnt(root_mnt, &root_parent);
        /* mount old root on put_old */
-       attach_mnt(root.mnt, &old);
+       attach_mnt(root_mnt, &old);
        /* mount new_root on / */
-       attach_mnt(new.mnt, &root_parent);
+       attach_mnt(new_mnt, &root_parent);
        touch_mnt_namespace(current->nsproxy->mnt_ns);
        br_write_unlock(vfsmount_lock);
        chroot_fs_refs(&root, &new);