btrfs: disable snapshot creation/deletion for extent tree v2

When we stop tracking metadata blocks all of snapshotting will break, so
disable it until I add the snapshot root and drop tree support.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/inode.c

@@ -4583,14 +4583,21 @@ out_up_write:
 static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
 {
 	struct inode *inode = d_inode(dentry);
+	struct btrfs_fs_info *fs_info = BTRFS_I(inode)->root->fs_info;
 	int err = 0;
 	struct btrfs_trans_handle *trans;
 	u64 last_unlink_trans;
 
 	if (inode->i_size > BTRFS_EMPTY_DIR_SIZE)
 		return -ENOTEMPTY;
-	if (btrfs_ino(BTRFS_I(inode)) == BTRFS_FIRST_FREE_OBJECTID)
+	if (btrfs_ino(BTRFS_I(inode)) == BTRFS_FIRST_FREE_OBJECTID) {
+		if (unlikely(btrfs_fs_incompat(fs_info, EXTENT_TREE_V2))) {
+			btrfs_err(fs_info,
+			"extent tree v2 doesn't support snapshot deletion yet");
+			return -EOPNOTSUPP;
+		}
 		return btrfs_delete_subvolume(dir, dentry);
+	}
 
 	trans = __unlink_start_trans(dir);
 	if (IS_ERR(trans))
@@ -4629,7 +4636,7 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry)
 	}
 out:
 	btrfs_end_transaction(trans);
-	btrfs_btree_balance_dirty(BTRFS_I(dir)->root->fs_info);
+	btrfs_btree_balance_dirty(fs_info);
 
 	return err;
 }

fs/btrfs/ioctl.c

@@ -751,6 +751,13 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir,
 	struct btrfs_trans_handle *trans;
 	int ret;
 
+	/* We do not support snapshotting right now. */
+	if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
+		btrfs_warn(fs_info,
+			   "extent tree v2 doesn't support snapshotting yet");
+		return -EOPNOTSUPP;
+	}
+
 	if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
 		return -EINVAL;
 
@@ -3174,6 +3181,13 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
 	int err = 0;
 	bool destroy_parent = false;
 
+	/* We don't support snapshots with extent tree v2 yet. */
+	if (btrfs_fs_incompat(fs_info, EXTENT_TREE_V2)) {
+		btrfs_err(fs_info,
+			  "extent tree v2 doesn't support snapshot deletion yet");
+		return -EOPNOTSUPP;
+	}
+
 	if (destroy_v2) {
 		vol_args2 = memdup_user(arg, sizeof(*vol_args2));
 		if (IS_ERR(vol_args2))