1 files changed, 182 insertions, 110 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index d7513485c1f3..9263995bf6a1 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -196,7 +196,7 @@ unsigned int mnt_get_count(struct vfsmount *mnt)
 #endif
 }
 
-struct vfsmount *alloc_vfsmnt(const char *name)
+static struct vfsmount *alloc_vfsmnt(const char *name)
 {
         struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
         if (mnt) {
@@ -466,15 +466,7 @@ static void __mnt_unmake_readonly(struct vfsmount *mnt)
         br_write_unlock(vfsmount_lock);
 }
 
-void simple_set_mnt(struct vfsmount *mnt, struct super_block *sb)
-{
-        mnt->mnt_sb = sb;
-        mnt->mnt_root = dget(sb->s_root);
-}
-
-EXPORT_SYMBOL(simple_set_mnt);
-
-void free_vfsmnt(struct vfsmount *mnt)
+static void free_vfsmnt(struct vfsmount *mnt)
 {
         kfree(mnt->mnt_devname);
         mnt_free_id(mnt);
@@ -678,6 +670,36 @@ static struct vfsmount *skip_mnt_tree(struct vfsmount *p)
         return p;
 }
 
+struct vfsmount *
+vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void *data)
+{
+        struct vfsmount *mnt;
+        struct dentry *root;
+
+        if (!type)
+                return ERR_PTR(-ENODEV);
+
+        mnt = alloc_vfsmnt(name);
+        if (!mnt)
+                return ERR_PTR(-ENOMEM);
+
+        if (flags & MS_KERNMOUNT)
+                mnt->mnt_flags = MNT_INTERNAL;
+
+        root = mount_fs(type, flags, name, data);
+        if (IS_ERR(root)) {
+                free_vfsmnt(mnt);
+                return ERR_CAST(root);
+        }
+
+        mnt->mnt_root = root;
+        mnt->mnt_sb = root->d_sb;
+        mnt->mnt_mountpoint = mnt->mnt_root;
+        mnt->mnt_parent = mnt;
+        return mnt;
+}
+EXPORT_SYMBOL_GPL(vfs_kern_mount);
+
 static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root,
                                         int flag)
 {
@@ -1641,9 +1663,35 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt,
         return err;
 }
 
+static int lock_mount(struct path *path)
+{
+        struct vfsmount *mnt;
+retry:
+        mutex_lock(&path->dentry->d_inode->i_mutex);
+        if (unlikely(cant_mount(path->dentry))) {
+                mutex_unlock(&path->dentry->d_inode->i_mutex);
+                return -ENOENT;
+        }
+        down_write(&namespace_sem);
+        mnt = lookup_mnt(path);
+        if (likely(!mnt))
+                return 0;
+        up_write(&namespace_sem);
+        mutex_unlock(&path->dentry->d_inode->i_mutex);
+        path_put(path);
+        path->mnt = mnt;
+        path->dentry = dget(mnt->mnt_root);
+        goto retry;
+}
+
+static void unlock_mount(struct path *path)
+{
+        up_write(&namespace_sem);
+        mutex_unlock(&path->dentry->d_inode->i_mutex);
+}
+
 static int graft_tree(struct vfsmount *mnt, struct path *path)
 {
-        int err;
         if (mnt->mnt_sb->s_flags & MS_NOUSER)
                 return -EINVAL;
 
@@ -1651,16 +1699,10 @@ static int graft_tree(struct vfsmount *mnt, struct path *path)
               S_ISDIR(mnt->mnt_root->d_inode->i_mode))
                 return -ENOTDIR;
 
-        err = -ENOENT;
-        mutex_lock(&path->dentry->d_inode->i_mutex);
-        if (cant_mount(path->dentry))
-                goto out_unlock;
+        if (d_unlinked(path->dentry))
+                return -ENOENT;
 
-        if (!d_unlinked(path->dentry))
-                err = attach_recursive_mnt(mnt, path, NULL);
-out_unlock:
-        mutex_unlock(&path->dentry->d_inode->i_mutex);
-        return err;
+        return attach_recursive_mnt(mnt, path, NULL);
 }
 
 /*
@@ -1723,6 +1765,7 @@ static int do_change_type(struct path *path, int flag)
 static int do_loopback(struct path *path, char *old_name,
                                 int recurse)
 {
+        LIST_HEAD(umount_list);
         struct path old_path;
         struct vfsmount *mnt = NULL;
         int err = mount_is_safe(path);
@@ -1734,13 +1777,16 @@ static int do_loopback(struct path *path, char *old_name,
         if (err)
                 return err;
 
-        down_write(&namespace_sem);
+        err = lock_mount(path);
+        if (err)
+                goto out;
+
         err = -EINVAL;
         if (IS_MNT_UNBINDABLE(old_path.mnt))
-                goto out;
+                goto out2;
 
         if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt))
-                goto out;
+                goto out2;
 
         err = -ENOMEM;
         if (recurse)
@@ -1749,20 +1795,18 @@ static int do_loopback(struct path *path, char *old_name,
                 mnt = clone_mnt(old_path.mnt, old_path.dentry, 0);
 
         if (!mnt)
-                goto out;
+                goto out2;
 
         err = graft_tree(mnt, path);
         if (err) {
-                LIST_HEAD(umount_list);
-
                 br_write_lock(vfsmount_lock);
                 umount_tree(mnt, 0, &umount_list);
                 br_write_unlock(vfsmount_lock);
-                release_mounts(&umount_list);
         }
-
+out2:
+        unlock_mount(path);
+        release_mounts(&umount_list);
 out:
-        up_write(&namespace_sem);
         path_put(&old_path);
         return err;
 }
@@ -1851,18 +1895,12 @@ static int do_move_mount(struct path *path, char *old_name)
         if (err)
                 return err;
 
-        down_write(&namespace_sem);
-        err = follow_down(path, true);
+        err = lock_mount(path);
         if (err < 0)
                 goto out;
 
         err = -EINVAL;
         if (!check_mnt(path->mnt) || !check_mnt(old_path.mnt))
-                goto out;
-
-        err = -ENOENT;
-        mutex_lock(&path->dentry->d_inode->i_mutex);
-        if (cant_mount(path->dentry))
                 goto out1;
 
         if (d_unlinked(path->dentry))
@@ -1904,16 +1942,87 @@ static int do_move_mount(struct path *path, char *old_name)
          * automatically */
         list_del_init(&old_path.mnt->mnt_expire);
 out1:
-        mutex_unlock(&path->dentry->d_inode->i_mutex);
+        unlock_mount(path);
 out:
-        up_write(&namespace_sem);
         if (!err)
                 path_put(&parent_path);
         path_put(&old_path);
         return err;
 }
 
-static int do_add_mount(struct vfsmount *, struct path *, int);
+static struct vfsmount *fs_set_subtype(struct vfsmount *mnt, const char *fstype)
+{
+        int err;
+        const char *subtype = strchr(fstype, '.');
+        if (subtype) {
+                subtype++;
+                err = -EINVAL;
+                if (!subtype[0])
+                        goto err;
+        } else
+                subtype = "";
+
+        mnt->mnt_sb->s_subtype = kstrdup(subtype, GFP_KERNEL);
+        err = -ENOMEM;
+        if (!mnt->mnt_sb->s_subtype)
+                goto err;
+        return mnt;
+
+ err:
+        mntput(mnt);
+        return ERR_PTR(err);
+}
+
+struct vfsmount *
+do_kern_mount(const char *fstype, int flags, const char *name, void *data)
+{
+        struct file_system_type *type = get_fs_type(fstype);
+        struct vfsmount *mnt;
+        if (!type)
+                return ERR_PTR(-ENODEV);
+        mnt = vfs_kern_mount(type, flags, name, data);
+        if (!IS_ERR(mnt) && (type->fs_flags & FS_HAS_SUBTYPE) &&
+            !mnt->mnt_sb->s_subtype)
+                mnt = fs_set_subtype(mnt, fstype);
+        put_filesystem(type);
+        return mnt;
+}
+EXPORT_SYMBOL_GPL(do_kern_mount);
+
+/*
+ * add a mount into a namespace's mount tree
+ */
+static int do_add_mount(struct vfsmount *newmnt, struct path *path, int mnt_flags)
+{
+        int err;
+
+        mnt_flags &= ~(MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL);
+
+        err = lock_mount(path);
+        if (err)
+                return err;
+
+        err = -EINVAL;
+        if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(path->mnt))
+                goto unlock;
+
+        /* Refuse the same filesystem on the same mount point */
+        err = -EBUSY;
+        if (path->mnt->mnt_sb == newmnt->mnt_sb &&
+            path->mnt->mnt_root == path->dentry)
+                goto unlock;
+
+        err = -EINVAL;
+        if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode))
+                goto unlock;
+
+        newmnt->mnt_flags = mnt_flags;
+        err = graft_tree(newmnt, path);
+
+unlock:
+        unlock_mount(path);
+        return err;
+}
 
 /*
  * create a new mount for userspace and request it to be added into the
@@ -1973,43 +2082,6 @@ fail:
         return err;
 }
 
-/*
- * add a mount into a namespace's mount tree
- */
-static int do_add_mount(struct vfsmount *newmnt, struct path *path, int mnt_flags)
-{
-        int err;
-
-        mnt_flags &= ~(MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL);
-
-        down_write(&namespace_sem);
-        /* Something was mounted here while we slept */
-        err = follow_down(path, true);
-        if (err < 0)
-                goto unlock;
-
-        err = -EINVAL;
-        if (!(mnt_flags & MNT_SHRINKABLE) && !check_mnt(path->mnt))
-                goto unlock;
-
-        /* Refuse the same filesystem on the same mount point */
-        err = -EBUSY;
-        if (path->mnt->mnt_sb == newmnt->mnt_sb &&
-            path->mnt->mnt_root == path->dentry)
-                goto unlock;
-
-        err = -EINVAL;
-        if (S_ISLNK(newmnt->mnt_root->d_inode->i_mode))
-                goto unlock;
-
-        newmnt->mnt_flags = mnt_flags;
-        err = graft_tree(newmnt, path);
-
-unlock:
-        up_write(&namespace_sem);
-        return err;
-}
-
 /**
  * mnt_set_expiry - Put a mount on an expiration list
  * @mnt: The mount to list.
@@ -2510,65 +2582,60 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
         error = user_path_dir(new_root, &new);
         if (error)
                 goto out0;
-        error = -EINVAL;
-        if (!check_mnt(new.mnt))
-                goto out1;
 
         error = user_path_dir(put_old, &old);
         if (error)
                 goto out1;
 
         error = security_sb_pivotroot(&old, &new);
-        if (error) {
-                path_put(&old);
-                goto out1;
-        }
+        if (error)
+                goto out2;
 
         get_fs_root(current->fs, &root);
-        down_write(&namespace_sem);
-        mutex_lock(&old.dentry->d_inode->i_mutex);
+        error = lock_mount(&old);
+        if (error)
+                goto out3;
+
         error = -EINVAL;
         if (IS_MNT_SHARED(old.mnt) ||
                 IS_MNT_SHARED(new.mnt->mnt_parent) ||
                 IS_MNT_SHARED(root.mnt->mnt_parent))
-                goto out2;
-        if (!check_mnt(root.mnt))
-                goto out2;
+                goto out4;
+        if (!check_mnt(root.mnt) || !check_mnt(new.mnt))
+                goto out4;
         error = -ENOENT;
-        if (cant_mount(old.dentry))
-                goto out2;
         if (d_unlinked(new.dentry))
-                goto out2;
+                goto out4;
         if (d_unlinked(old.dentry))
-                goto out2;
+                goto out4;
         error = -EBUSY;
         if (new.mnt == root.mnt ||
             old.mnt == root.mnt)
-                goto out2; /* loop, on the same file system  */
+                goto out4; /* loop, on the same file system  */
         error = -EINVAL;
         if (root.mnt->mnt_root != root.dentry)
-                goto out2; /* not a mountpoint */
+                goto out4; /* not a mountpoint */
         if (root.mnt->mnt_parent == root.mnt)
-                goto out2; /* not attached */
+                goto out4; /* not attached */
         if (new.mnt->mnt_root != new.dentry)
-                goto out2; /* not a mountpoint */
+                goto out4; /* not a mountpoint */
         if (new.mnt->mnt_parent == new.mnt)
-                goto out2; /* not attached */
+                goto out4; /* not attached */
         /* make sure we can reach put_old from new_root */
         tmp = old.mnt;
-        br_write_lock(vfsmount_lock);
         if (tmp != new.mnt) {
                 for (;;) {
                         if (tmp->mnt_parent == tmp)
-                                goto out3; /* already mounted on put_old */
+                                goto out4; /* already mounted on put_old */
                         if (tmp->mnt_parent == new.mnt)
                                 break;
                         tmp = tmp->mnt_parent;
                 }
                 if (!is_subdir(tmp->mnt_mountpoint, new.dentry))
-                        goto out3;
+                        goto out4;
         } else if (!is_subdir(old.dentry, new.dentry))
-                goto out3;
+                goto out4;
+        br_write_lock(vfsmount_lock);
         detach_mnt(new.mnt, &parent_path);
         detach_mnt(root.mnt, &root_parent);
         /* mount old root on put_old */
@@ -2578,22 +2645,21 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
         touch_mnt_namespace(current->nsproxy->mnt_ns);
         br_write_unlock(vfsmount_lock);
         chroot_fs_refs(&root, &new);
-
         error = 0;
-        path_put(&root_parent);
-        path_put(&parent_path);
-out2:
-        mutex_unlock(&old.dentry->d_inode->i_mutex);
-        up_write(&namespace_sem);
+out4:
+        unlock_mount(&old);
+        if (!error) {
+                path_put(&root_parent);
+                path_put(&parent_path);
+        }
+out3:
         path_put(&root);
+out2:
         path_put(&old);
 out1:
         path_put(&new);
 out0:
         return error;
-out3:
-        br_write_unlock(vfsmount_lock);
-        goto out2;
 }
 
 static void __init init_mount_tree(void)
@@ -2668,3 +2734,9 @@ void put_mnt_ns(struct mnt_namespace *ns)
         kfree(ns);
 }
 EXPORT_SYMBOL(put_mnt_ns);
+
+struct vfsmount *kern_mount_data(struct file_system_type *type, void *data)
+{
+        return vfs_kern_mount(type, MS_KERNMOUNT, type->name, data);
+}
+EXPORT_SYMBOL_GPL(kern_mount_data);