From patchwork Tue Jul 31 07:18:29 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miao Xie X-Patchwork-Id: 1258391 Return-Path: X-Original-To: patchwork-linux-btrfs@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id CD0AEDF26F for ; Tue, 31 Jul 2012 07:19:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755623Ab2GaHTT (ORCPT ); Tue, 31 Jul 2012 03:19:19 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:4111 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1755605Ab2GaHTS (ORCPT ); Tue, 31 Jul 2012 03:19:18 -0400 X-IronPort-AV: E=Sophos;i="4.77,682,1336320000"; d="scan'208";a="5517126" Received: from unknown (HELO tang.cn.fujitsu.com) ([10.167.250.3]) by song.cn.fujitsu.com with ESMTP; 31 Jul 2012 15:18:20 +0800 Received: from fnstmail02.fnst.cn.fujitsu.com (tang.cn.fujitsu.com [127.0.0.1]) by tang.cn.fujitsu.com (8.14.3/8.13.1) with ESMTP id q6V7JGcb011251; Tue, 31 Jul 2012 15:19:17 +0800 Received: from [10.167.225.199] ([10.167.225.199]) by fnstmail02.fnst.cn.fujitsu.com (Lotus Domino Release 8.5.3) with ESMTP id 2012073115195090-31783 ; Tue, 31 Jul 2012 15:19:50 +0800 Message-ID: <501786C5.1060905@cn.fujitsu.com> Date: Tue, 31 Jul 2012 15:18:29 +0800 From: Miao Xie Reply-To: miaox@cn.fujitsu.com User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 MIME-Version: 1.0 To: Linux Btrfs CC: Seto Hidetoshi , David Sterba Subject: [PATCH V2 2/2] Btrfs: fix the snapshot that should not exist X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/07/31 15:19:50, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/07/31 15:19:52, Serialize complete at 2012/07/31 15:19:52 Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org The snapshot should be the image of the fs tree before it was created, so the metadata of the snapshot should not exist in the its tree. But now, we found the directory item and directory name index is in both the snapshot tree and the fs tree. It introduces some problems and makes the users feel strange: # mkfs.btrfs /dev/sda1 # mount /dev/sda1 /mnt # mkdir /mnt/1 # cd /mnt/1 # btrfs subvolume snapshot /mnt snap0 # ls -a /mnt/1/snap0/1 . .. [no other file/dir] # ll /mnt/1/snap0/ total 0 drwxr-xr-x 1 root root 10 Ju1 24 12:11 1 ^^^ There is no file/dir in it, but it's size is 10 # cd /mnt/1/snap0/1/snap0 [Enter a unexisted directory successfully...] There is nothing in the directory 1 in snap0, but btrfs told the length of this directory is 10. Beside that, we can enter an unexisted directory, it is very strange to the users. # btrfs subvolume snapshot /mnt/1/snap0 /mnt/snap1 # ll /mnt/1/snap0/1/ total 0 [None] # ll /mnt/snap1/1/ total 0 drwxr-xr-x 1 root root 0 Ju1 24 12:14 snap0 And the source of snap1 did have any directory in Directory 1, but snap1 have a snap0, it is different between the source and the snapshot. So I think we should insert directory item and directory name index and update the parent inode as the last step of snapshot creation, and do not leave the useless metadata in the file tree. Signed-off-by: Miao Xie --- Changelog v1 -> v2: - Add comment to explain why we need deal with the delayed items after snapshot creation and why this operation do not corrupt the metadata. - Move dropping dput() to patch 1/2 --- fs/btrfs/transaction.c | 66 +++++++++++++++++++++++++++++++++++++---------- 1 files changed, 52 insertions(+), 14 deletions(-) diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 4d579fe..c3251e2 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -922,6 +922,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, struct btrfs_root *parent_root; struct btrfs_block_rsv *rsv; struct inode *parent_inode; + struct btrfs_path *path; + struct btrfs_dir_item *dir_item; struct dentry *parent; struct dentry *dentry; struct extent_buffer *tmp; @@ -932,6 +934,12 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, u64 objectid; u64 root_flags; + path = btrfs_alloc_path(); + if (!path) { + ret = pending->error = -ENOMEM; + goto path_alloc_fail; + } + new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS); if (!new_root_item) { ret = pending->error = -ENOMEM; @@ -973,22 +981,20 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, */ ret = btrfs_set_inode_index(parent_inode, &index); BUG_ON(ret); /* -ENOMEM */ - ret = btrfs_insert_dir_item(trans, parent_root, - dentry->d_name.name, dentry->d_name.len, - parent_inode, &key, - BTRFS_FT_DIR, index); - if (ret == -EEXIST) { + + /* check if there is a file/dir which has the same name. */ + dir_item = btrfs_lookup_dir_item(NULL, parent_root, path, + btrfs_ino(parent_inode), + dentry->d_name.name, + dentry->d_name.len, 0); + if (dir_item != NULL && !IS_ERR(dir_item)) { pending->error = -EEXIST; goto fail; - } else if (ret) { + } else if (IS_ERR(dir_item)) { + ret = PTR_ERR(dir_item); goto abort_trans; } - - btrfs_i_size_write(parent_inode, parent_inode->i_size + - dentry->d_name.len * 2); - ret = btrfs_update_inode(trans, parent_root, parent_inode); - if (ret) - goto abort_trans; + btrfs_release_path(path); /* * pull in the delayed directory update @@ -1062,12 +1068,29 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans, ret = btrfs_reloc_post_snapshot(trans, pending); if (ret) goto abort_trans; + + ret = btrfs_insert_dir_item(trans, parent_root, + dentry->d_name.name, dentry->d_name.len, + parent_inode, &key, + BTRFS_FT_DIR, index); + /* We have check then name at the beginning, so it is impossible. */ + BUG_ON(ret == -EEXIST); + if (ret) + goto abort_trans; + + btrfs_i_size_write(parent_inode, parent_inode->i_size + + dentry->d_name.len * 2); + ret = btrfs_update_inode(trans, parent_root, parent_inode); + if (ret) + goto abort_trans; fail: dput(parent); trans->block_rsv = rsv; no_free_objectid: kfree(new_root_item); root_item_alloc_fail: + btrfs_free_path(path); +path_alloc_fail: btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1); return ret; @@ -1385,13 +1408,28 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans, */ mutex_lock(&root->fs_info->reloc_mutex); - ret = btrfs_run_delayed_items(trans, root); + /* + * We needn't worry about the delayed items because we will + * deal with them in create_pending_snapshot(), which is the + * core function of the snapshot creation. + */ + ret = create_pending_snapshots(trans, root->fs_info); if (ret) { mutex_unlock(&root->fs_info->reloc_mutex); goto cleanup_transaction; } - ret = create_pending_snapshots(trans, root->fs_info); + /* + * We insert the dir indexes of the snapshots and update the inode + * of the snapshots' parents after the snapshot creation, so there + * are some delayed items which are not dealt with. Now deal with + * them. + * + * We needn't worry that this operation will corrupt the snapshots, + * because all the tree which are snapshoted will be forced to COW + * the nodes and leaves. + */ + ret = btrfs_run_delayed_items(trans, root); if (ret) { mutex_unlock(&root->fs_info->reloc_mutex); goto cleanup_transaction;