[RFC] Removing a subvolume by an ordinary user

Commit Message

Goffredo Baroncelli Sept. 18, 2010, 1:15 p.m. UTC

None

Patch

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index f08427c..47d11d8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2944,6 +2944,86 @@  int btrfs_unlink_subvol(struct btrfs_trans_handle *trans,
 	return 0;
 }
 
+int may_destroy_subvol(struct btrfs_root *root);
+static noinline int btrfs_snap_destroy(struct inode *dir,
+				       struct dentry *dentry)
+
+{
+
+	struct inode *inode;
+	struct btrfs_root *root = BTRFS_I(dir)->root;
+	struct btrfs_root *dest = NULL;
+	struct btrfs_trans_handle *trans;
+
+	int ret;
+	int err = 0;
+
+
+	if (IS_ERR(dentry)) {
+		err = PTR_ERR(dentry);
+		goto out;
+	}
+
+	if (!dentry->d_inode) {
+		err = -ENOENT;
+		goto out;
+	}
+
+	inode = dentry->d_inode;
+	if (inode->i_ino != BTRFS_FIRST_FREE_OBJECTID) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	dest = BTRFS_I(inode)->root;
+
+	down_write(&root->fs_info->subvol_sem);
+
+	err = may_destroy_subvol(dest);
+	if (err)
+		goto out_up_write;
+
+	trans = btrfs_start_transaction(root, 0);
+	if (IS_ERR(trans)) {
+		err = PTR_ERR(trans);
+		goto out_up_write;
+	}
+	trans->block_rsv = &root->fs_info->global_block_rsv;
+
+	ret = btrfs_unlink_subvol(trans, root, dir,
+				dest->root_key.objectid,
+				dentry->d_name.name,
+				dentry->d_name.len);
+	BUG_ON(ret);
+
+	btrfs_record_root_in_trans(trans, dest);
+
+	memset(&dest->root_item.drop_progress, 0,
+		sizeof(dest->root_item.drop_progress));
+	dest->root_item.drop_level = 0;
+	btrfs_set_root_refs(&dest->root_item, 0);
+
+	if (!xchg(&dest->orphan_item_inserted, 1)) {
+		ret = btrfs_insert_orphan_item(trans,
+					root->fs_info->tree_root,
+					dest->root_key.objectid);
+		BUG_ON(ret);
+	}
+
+	ret = btrfs_commit_transaction(trans, root);
+	BUG_ON(ret);
+	inode->i_flags |= S_DEAD;
+out_up_write:
+	up_write(&root->fs_info->subvol_sem);
+	if (!err) {
+		shrink_dcache_sb(root->fs_info->sb);
+		btrfs_invalidate_inodes(dest);
+		/*d_delete(dentry);*/
+	}
+out:
+	return err;
+}
+
 static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
 {
 	struct inode *inode = dentry->d_inode;
@@ -2952,10 +3032,12 @@  static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
 	struct btrfs_trans_handle *trans;
 	unsigned long nr = 0;
 
-	if (inode->i_size > BTRFS_EMPTY_DIR_SIZE ||
-	    inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
+	if (inode->i_size > BTRFS_EMPTY_DIR_SIZE)
 		return -ENOTEMPTY;
 
+	if (inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
+		return btrfs_snap_destroy(dir, dentry);
+
 	trans = __unlink_start_trans(dir, dentry);
 	if (IS_ERR(trans))
 		return PTR_ERR(trans);
@@ -4242,7 +4324,6 @@  static int btrfs_real_readdir(struct file *filp, void *dirent,
 			over = filldir(dirent, name_ptr, name_len,
 				       found_key.offset, location.objectid,
 				       d_type);
-
 skip:
 			if (name_ptr != tmp_name)
 				kfree(name_ptr);
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 9254b3d..a7b242e 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -855,7 +855,7 @@  out:
 /*
  * helper to check if the subvolume references other subvolumes
  */
-static noinline int may_destroy_subvol(struct btrfs_root *root)
+int may_destroy_subvol(struct btrfs_root *root)
 {
 	struct btrfs_path *path;
 	struct btrfs_key key;