From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mout.gmx.net ([212.227.17.22]:60689 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752103AbeFKFU5 (ORCPT ); Mon, 11 Jun 2018 01:20:57 -0400 Subject: Re: [PATCH 11/15] btrfs-progs: Add delayed refs infrastructure To: Nikolay Borisov , linux-btrfs@vger.kernel.org References: <1528462078-24490-1-git-send-email-nborisov@suse.com> <1528462078-24490-12-git-send-email-nborisov@suse.com> From: Qu Wenruo Message-ID: <091f70e9-e31f-2a03-cc90-6697803f8c3c@gmx.com> Date: Mon, 11 Jun 2018 13:20:44 +0800 MIME-Version: 1.0 In-Reply-To: <1528462078-24490-12-git-send-email-nborisov@suse.com> Content-Type: text/plain; charset=utf-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 2018年06月08日 20:47, Nikolay Borisov wrote: > This commit pulls those portions of the kernel implementation of > delayed refs which are necessary to have them working in user-space. > I've done the following modifications: > > 1. Replaced all kmem_cache_alloc calls to kmalloc. > > 2. Removed all locking-related code, since we are single threaded in > userspace. > > 3. Removed code which deals with data refs - delayed refs in user space > are going to be used only for cowonly trees. That's pretty good, although still some data ref related structures/functions are left. > > Signed-off-by: Nikolay Borisov > --- > Makefile | 3 +- > ctree.h | 3 + > delayed-ref.c | 608 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > delayed-ref.h | 225 ++++++++++++++++++++++ > extent-tree.c | 228 ++++++++++++++++++++++ > kerncompat.h | 8 + > transaction.h | 4 + > 7 files changed, 1078 insertions(+), 1 deletion(-) > create mode 100644 delayed-ref.c > create mode 100644 delayed-ref.h > > diff --git a/Makefile b/Makefile > index 544410e6440c..9508ad4f11e6 100644 > --- a/Makefile > +++ b/Makefile > @@ -116,7 +116,8 @@ objects = ctree.o disk-io.o kernel-lib/radix-tree.o extent-tree.o print-tree.o \ > qgroup.o free-space-cache.o kernel-lib/list_sort.o props.o \ > kernel-shared/ulist.o qgroup-verify.o backref.o string-table.o task-utils.o \ > inode.o file.o find-root.o free-space-tree.o help.o send-dump.o \ > - fsfeatures.o kernel-lib/tables.o kernel-lib/raid56.o transaction.o > + fsfeatures.o kernel-lib/tables.o kernel-lib/raid56.o transaction.o \ > + delayed-ref.o > cmds_objects = cmds-subvolume.o cmds-filesystem.o cmds-device.o cmds-scrub.o \ > cmds-inspect.o cmds-balance.o cmds-send.o cmds-receive.o \ > cmds-quota.o cmds-qgroup.o cmds-replace.o check/main.o \ > diff --git a/ctree.h b/ctree.h > index b30a946658ce..d1ea45571d1e 100644 > --- a/ctree.h > +++ b/ctree.h > @@ -2812,4 +2812,7 @@ int btrfs_punch_hole(struct btrfs_trans_handle *trans, > int btrfs_read_file(struct btrfs_root *root, u64 ino, u64 start, int len, > char *dest); > > + > +/* extent-tree.c */ > +int btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, unsigned long nr); > #endif > diff --git a/delayed-ref.c b/delayed-ref.c > new file mode 100644 > index 000000000000..f3fa50239380 > --- /dev/null > +++ b/delayed-ref.c > @@ -0,0 +1,608 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) 2009 Oracle. All rights reserved. > + */ > + > +#include "ctree.h" > +#include "btrfs-list.h" > +#include "delayed-ref.h" > +#include "transaction.h" > + > +/* > + * delayed back reference update tracking. For subvolume trees > + * we queue up extent allocations and backref maintenance for > + * delayed processing. This avoids deep call chains where we > + * add extents in the middle of btrfs_search_slot, and it allows > + * us to buffer up frequently modified backrefs in an rb tree instead > + * of hammering updates on the extent allocation tree. > + */ A little more explanation on how delayed ref works will be more appricated. [snip] > +struct btrfs_delayed_tree_ref { > + struct btrfs_delayed_ref_node node; > + u64 root; > + u64 parent; > + int level; > +}; > + > +struct btrfs_delayed_data_ref { > + struct btrfs_delayed_ref_node node; > + u64 root; > + u64 parent; > + u64 objectid; > + u64 offset; > +}; Since we don't use this structure and don't support data ref yet, what about just removing this definiation? [snip] > +struct btrfs_delayed_ref_head * > +btrfs_select_ref_head(struct btrfs_trans_handle *trans); > + > +/* > + * helper functions to cast a node into its container > + */ > +static inline struct btrfs_delayed_tree_ref * > +btrfs_delayed_node_to_tree_ref(struct btrfs_delayed_ref_node *node) > +{ > + return container_of(node, struct btrfs_delayed_tree_ref, node); > +} > + > +static inline struct btrfs_delayed_data_ref * > +btrfs_delayed_node_to_data_ref(struct btrfs_delayed_ref_node *node) > +{ > + return container_of(node, struct btrfs_delayed_data_ref, node); > +} So is the only user of btrfs_delayed_data_ref structure. Thanks, Qu