From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:47501 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755768AbeDFOsc (ORCPT ); Fri, 6 Apr 2018 10:48:32 -0400 Date: Fri, 6 Apr 2018 16:46:02 +0200 From: David Sterba To: Misono Tomohiro Cc: linux-btrfs Subject: Re: [PATCH v3 2/3] btrfs: Allow rmdir(2) to delete a subvolume Message-ID: <20180406144602.GF8557@twin.jikos.cz> Reply-To: dsterba@suse.cz References: <1c798713-c896-f20c-5551-b8480ca74b72@jp.fujitsu.com> <47eb3e91-8059-e273-b2f1-c648f94a3a3b@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <47eb3e91-8059-e273-b2f1-c648f94a3a3b@jp.fujitsu.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Fri, Mar 30, 2018 at 03:16:47PM +0900, Misono Tomohiro wrote: > This patch changes the behavior of rmdir(2) to allow it to delete > an empty subvolume by default, unless it is not a default subvolume > and send is not in progress. > > New function btrfs_delete_subvolume() is almost equal to the second half > of btrfs_ioctl_snap_destroy(). This function requires inode_lock for both > @dir and inode of @dentry. For rmdir(2) it is already acquired in vfs > layer before calling btrfs_rmdir(). > > Note that while a non-privileged user cannot delete a read-only subvolume > by "btrfs subvolume delete" when user_subvol_rm_allowd mount option is > enabled, rmdir(2) can delete an empty read-only subvolume. > > Tested-by: Goffredo Baroncelli > Signed-off-by: Tomohiro Misono > --- > fs/btrfs/inode.c | 141 ++++++++++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 140 insertions(+), 1 deletion(-) > > diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c > index db66fa4fede6..84dbb9cafd6b 100644 > --- a/fs/btrfs/inode.c > +++ b/fs/btrfs/inode.c > @@ -4387,6 +4387,145 @@ noinline int may_destroy_subvol(struct btrfs_root *root) > return ret; > } > > +static int btrfs_delete_subvolume(struct inode *dir, struct dentry *dentry) > +{ > + struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb); > + struct btrfs_root *root = BTRFS_I(dir)->root; > + struct inode *inode = d_inode(dentry); > + struct btrfs_root *dest = BTRFS_I(inode)->root; > + struct btrfs_trans_handle *trans; > + struct btrfs_block_rsv block_rsv; > + u64 root_flags; > + u64 qgroup_reserved; > + int ret; > + int err; > + > + /* > + * Don't allow to delete a subvolume with send in progress. This is > + * inside the i_mutex so the error handling that has to drop the bit > + * again is not run concurrently. > + */ > + spin_lock(&dest->root_item_lock); > + root_flags = btrfs_root_flags(&dest->root_item); > + if (dest->send_in_progress == 0) { > + btrfs_set_root_flags(&dest->root_item, > + root_flags | BTRFS_ROOT_SUBVOL_DEAD); > + spin_unlock(&dest->root_item_lock); > + } else { > + spin_unlock(&dest->root_item_lock); > + btrfs_warn(fs_info, > + "Attempt to delete subvolume %llu during send", > + dest->root_key.objectid); > + err = -EPERM; > + return err; > + } > + > + down_write(&fs_info->subvol_sem); > + > + err = may_destroy_subvol(dest); > + if (err) > + goto out_up_write; > + > + btrfs_init_block_rsv(&block_rsv, BTRFS_BLOCK_RSV_TEMP); > + /* > + * One for dir inode, two for dir entries, two for root > + * ref/backref. > + */ > + err = btrfs_subvolume_reserve_metadata(root, &block_rsv, > + 5, &qgroup_reserved, true); > + if (err) > + goto out_up_write; > + > + trans = btrfs_start_transaction(root, 0); > + if (IS_ERR(trans)) { > + err = PTR_ERR(trans); > + goto out_release; > + } > + trans->block_rsv = &block_rsv; > + trans->bytes_reserved = block_rsv.size; > + > + btrfs_record_snapshot_destroy(trans, BTRFS_I(dir)); > + > + ret = btrfs_unlink_subvol(trans, root, dir, > + dest->root_key.objectid, > + dentry->d_name.name, > + dentry->d_name.len); > + if (ret) { > + err = ret; > + btrfs_abort_transaction(trans, ret); > + goto out_end_trans; > + } > + > + 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 (!test_and_set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &dest->state)) { > + ret = btrfs_insert_orphan_item(trans, > + fs_info->tree_root, > + dest->root_key.objectid); > + if (ret) { > + btrfs_abort_transaction(trans, ret); > + err = ret; > + goto out_end_trans; > + } > + } > + > + ret = btrfs_uuid_tree_rem(trans, fs_info, dest->root_item.uuid, > + BTRFS_UUID_KEY_SUBVOL, > + dest->root_key.objectid); > + if (ret && ret != -ENOENT) { > + btrfs_abort_transaction(trans, ret); > + err = ret; > + goto out_end_trans; > + } > + if (!btrfs_is_empty_uuid(dest->root_item.received_uuid)) { > + ret = btrfs_uuid_tree_rem(trans, fs_info, > + dest->root_item.received_uuid, > + BTRFS_UUID_KEY_RECEIVED_SUBVOL, > + dest->root_key.objectid); > + if (ret && ret != -ENOENT) { > + btrfs_abort_transaction(trans, ret); > + err = ret; > + goto out_end_trans; > + } > + } > + > +out_end_trans: > + trans->block_rsv = NULL; > + trans->bytes_reserved = 0; > + ret = btrfs_end_transaction(trans); > + if (ret && !err) > + err = ret; > + inode->i_flags |= S_DEAD; > +out_release: > + btrfs_subvolume_release_metadata(fs_info, &block_rsv); > +out_up_write: > + up_write(&fs_info->subvol_sem); > + if (err) { > + spin_lock(&dest->root_item_lock); > + root_flags = btrfs_root_flags(&dest->root_item); > + btrfs_set_root_flags(&dest->root_item, > + root_flags & ~BTRFS_ROOT_SUBVOL_DEAD); > + spin_unlock(&dest->root_item_lock); > + } else { > + d_invalidate(dentry); > + btrfs_invalidate_inodes(dest); > + ASSERT(dest->send_in_progress == 0); > + > + /* the last ref */ > + if (dest->ino_cache_inode) { > + iput(dest->ino_cache_inode); > + dest->ino_cache_inode = NULL; > + } > + } > + > + return err; > +} The change separation is still not right. Patch 2+3 should factor out btrfs_delete_subvolume and do not any changes to rmdir behaviour. The following patch will do what's in the hunk below, with enough reasonging why it is so. > + > static int btrfs_rmdir(struct inode *dir, struct dentry *dentry) > { > struct inode *inode = d_inode(dentry); > @@ -4398,7 +4537,7 @@ static int btrfs_rmdir(struct inode *dir, struct dentry *dentry) > if (inode->i_size > BTRFS_EMPTY_DIR_SIZE) > return -ENOTEMPTY; > if (btrfs_ino(BTRFS_I(inode)) == BTRFS_FIRST_FREE_OBJECTID) > - return -EPERM; > + return btrfs_delete_subvolume(dir, dentry); > > trans = __unlink_start_trans(dir); > if (IS_ERR(trans))