From patchwork Thu Jun 3 00:55:13 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roman Gushchin X-Patchwork-Id: 12295949 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF9EBC47083 for ; Thu, 3 Jun 2021 00:55:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A115C613DC for ; Thu, 3 Jun 2021 00:55:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A115C613DC Authentication-Results: mail.kernel.org; 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Wed, 2 Jun 2021 17:55:28 -0700 Received: by devvm3388.prn0.facebook.com (Postfix, from userid 111017) id 969557F192A4; Wed, 2 Jun 2021 17:55:22 -0700 (PDT) From: Roman Gushchin To: Jan Kara , Tejun Heo CC: , , , Alexander Viro , Dennis Zhou , Dave Chinner , , Roman Gushchin Subject: [PATCH v6 1/5] writeback, cgroup: switch to rcu_work API in inode_switch_wbs() Date: Wed, 2 Jun 2021 17:55:13 -0700 Message-ID: <20210603005517.1403689-2-guro@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210603005517.1403689-1-guro@fb.com> References: <20210603005517.1403689-1-guro@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: fIpSiMQunOhavwhRXGUgtu5ddJfxnojY X-Proofpoint-ORIG-GUID: fIpSiMQunOhavwhRXGUgtu5ddJfxnojY X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-06-02_11:2021-06-02,2021-06-02 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 suspectscore=0 mlxlogscore=999 priorityscore=1501 lowpriorityscore=0 impostorscore=0 bulkscore=0 malwarescore=0 phishscore=0 spamscore=0 adultscore=0 mlxscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106030004 X-FB-Internal: deliver Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=fb.com header.s=facebook header.b=YFPvi2Yw; dmarc=pass (policy=reject) header.from=fb.com; spf=pass (imf15.hostedemail.com: domain of "prvs=578884e26b=guro@fb.com" designates 67.231.153.30 as permitted sender) smtp.mailfrom="prvs=578884e26b=guro@fb.com" X-Stat-Signature: 36gnza4e4edsor6fy67w3aqyzka8hpmq X-Rspamd-Queue-Id: 65CD5A00025C X-Rspamd-Server: rspam02 X-HE-Tag: 1622681745-757252 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Inode's wb switching requires two steps divided by an RCU grace period. It's currently implemented as an RCU callback inode_switch_wbs_rcu_fn(), which schedules inode_switch_wbs_work_fn() as a work. Switching to the rcu_work API allows to do the same in a cleaner and slightly shorter form. Signed-off-by: Roman Gushchin Reviewed-by: Jan Kara --- fs/fs-writeback.c | 18 ++++-------------- 1 file changed, 4 insertions(+), 14 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index e91980f49388..1f51857e41d1 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -335,8 +335,7 @@ struct inode_switch_wbs_context { struct inode *inode; struct bdi_writeback *new_wb; - struct rcu_head rcu_head; - struct work_struct work; + struct rcu_work work; }; static void bdi_down_write_wb_switch_rwsem(struct backing_dev_info *bdi) @@ -352,7 +351,7 @@ static void bdi_up_write_wb_switch_rwsem(struct backing_dev_info *bdi) static void inode_switch_wbs_work_fn(struct work_struct *work) { struct inode_switch_wbs_context *isw = - container_of(work, struct inode_switch_wbs_context, work); + container_of(to_rcu_work(work), struct inode_switch_wbs_context, work); struct inode *inode = isw->inode; struct backing_dev_info *bdi = inode_to_bdi(inode); struct address_space *mapping = inode->i_mapping; @@ -469,16 +468,6 @@ static void inode_switch_wbs_work_fn(struct work_struct *work) atomic_dec(&isw_nr_in_flight); } -static void inode_switch_wbs_rcu_fn(struct rcu_head *rcu_head) -{ - struct inode_switch_wbs_context *isw = container_of(rcu_head, - struct inode_switch_wbs_context, rcu_head); - - /* needs to grab bh-unsafe locks, bounce to work item */ - INIT_WORK(&isw->work, inode_switch_wbs_work_fn); - queue_work(isw_wq, &isw->work); -} - /** * inode_switch_wbs - change the wb association of an inode * @inode: target inode @@ -534,7 +523,8 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id) * lock so that stat transfer can synchronize against them. * Let's continue after I_WB_SWITCH is guaranteed to be visible. */ - call_rcu(&isw->rcu_head, inode_switch_wbs_rcu_fn); + INIT_RCU_WORK(&isw->work, inode_switch_wbs_work_fn); + queue_rcu_work(isw_wq, &isw->work); atomic_inc(&isw_nr_in_flight); return; From patchwork Thu Jun 3 00:55:14 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roman Gushchin X-Patchwork-Id: 12295941 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 093D3C47093 for ; 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Wed, 02 Jun 2021 17:55:24 -0700 Received: from intmgw002.48.prn1.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c085:21d::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Wed, 2 Jun 2021 17:55:22 -0700 Received: by devvm3388.prn0.facebook.com (Postfix, from userid 111017) id 9B42A7F192A6; Wed, 2 Jun 2021 17:55:22 -0700 (PDT) From: Roman Gushchin To: Jan Kara , Tejun Heo CC: , , , Alexander Viro , Dennis Zhou , Dave Chinner , , Roman Gushchin Subject: [PATCH v6 2/5] writeback, cgroup: keep list of inodes attached to bdi_writeback Date: Wed, 2 Jun 2021 17:55:14 -0700 Message-ID: <20210603005517.1403689-3-guro@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210603005517.1403689-1-guro@fb.com> References: <20210603005517.1403689-1-guro@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-ORIG-GUID: 44yj90RzWD3ZPF2EaSHdHNEhYUK1iTNf X-Proofpoint-GUID: 44yj90RzWD3ZPF2EaSHdHNEhYUK1iTNf X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-06-02_11:2021-06-02,2021-06-02 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxscore=0 mlxlogscore=458 malwarescore=0 adultscore=0 phishscore=0 priorityscore=1501 suspectscore=0 clxscore=1015 spamscore=0 bulkscore=0 impostorscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106030003 X-FB-Internal: deliver Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=fb.com header.s=facebook header.b=a4i16z6Y; dmarc=pass (policy=reject) header.from=fb.com; spf=pass (imf12.hostedemail.com: domain of "prvs=578884e26b=guro@fb.com" designates 67.231.153.30 as permitted sender) smtp.mailfrom="prvs=578884e26b=guro@fb.com" X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 57090420 X-Stat-Signature: 9mrjhch7phg8qs4hg4p7j7wepd3kz315 X-HE-Tag: 1622681707-532329 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Currently there is no way to iterate over inodes attached to a specific cgwb structure. It limits the ability to efficiently reclaim the writeback structure itself and associated memory and block cgroup structures without scanning all inodes belonging to a sb, which can be prohibitively expensive. While dirty/in-active-writeback an inode belongs to one of the bdi_writeback's io lists: b_dirty, b_io, b_more_io and b_dirty_time. Once cleaned up, it's removed from all io lists. So the inode->i_io_list can be reused to maintain the list of inodes, attached to a bdi_writeback structure. This patch introduces a new wb->b_attached list, which contains all inodes which were dirty at least once and are attached to the given cgwb. Inodes attached to the root bdi_writeback structures are never placed on such list. The following patch will use this list to try to release cgwbs structures more efficiently. Suggested-by: Jan Kara Signed-off-by: Roman Gushchin Reviewed-by: Jan Kara --- fs/fs-writeback.c | 88 ++++++++++++++++++++------------ include/linux/backing-dev-defs.h | 1 + mm/backing-dev.c | 2 + 3 files changed, 57 insertions(+), 34 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 1f51857e41d1..09d2770449ef 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -131,25 +131,6 @@ static bool inode_io_list_move_locked(struct inode *inode, return false; } -/** - * inode_io_list_del_locked - remove an inode from its bdi_writeback IO list - * @inode: inode to be removed - * @wb: bdi_writeback @inode is being removed from - * - * Remove @inode which may be on one of @wb->b_{dirty|io|more_io} lists and - * clear %WB_has_dirty_io if all are empty afterwards. - */ -static void inode_io_list_del_locked(struct inode *inode, - struct bdi_writeback *wb) -{ - assert_spin_locked(&wb->list_lock); - assert_spin_locked(&inode->i_lock); - - inode->i_state &= ~I_SYNC_QUEUED; - list_del_init(&inode->i_io_list); - wb_io_lists_depopulated(wb); -} - static void wb_wakeup(struct bdi_writeback *wb) { spin_lock_bh(&wb->work_lock); @@ -278,6 +259,28 @@ void __inode_attach_wb(struct inode *inode, struct page *page) } EXPORT_SYMBOL_GPL(__inode_attach_wb); +/** + * inode_cgwb_move_to_attached - put the inode onto wb->b_attached list + * @inode: inode of interest with i_lock held + * @wb: target bdi_writeback + * + * Remove the inode from wb's io lists and if necessarily put onto b_attached + * list. Only inodes attached to cgwb's are kept on this list. + */ +static void inode_cgwb_move_to_attached(struct inode *inode, + struct bdi_writeback *wb) +{ + assert_spin_locked(&wb->list_lock); + assert_spin_locked(&inode->i_lock); + + inode->i_state &= ~I_SYNC_QUEUED; + if (wb != &wb->bdi->wb) + list_move(&inode->i_io_list, &wb->b_attached); + else + list_del_init(&inode->i_io_list); + wb_io_lists_depopulated(wb); +} + /** * locked_inode_to_wb_and_lock_list - determine a locked inode's wb and lock it * @inode: inode of interest with i_lock held @@ -418,21 +421,28 @@ static void inode_switch_wbs_work_fn(struct work_struct *work) wb_get(new_wb); /* - * Transfer to @new_wb's IO list if necessary. The specific list - * @inode was on is ignored and the inode is put on ->b_dirty which - * is always correct including from ->b_dirty_time. The transfer - * preserves @inode->dirtied_when ordering. + * Transfer to @new_wb's IO list if necessary. If the @inode is dirty, + * the specific list @inode was on is ignored and the @inode is put on + * ->b_dirty which is always correct including from ->b_dirty_time. + * The transfer preserves @inode->dirtied_when ordering. If the @inode + * was clean, it means it was on the b_attached list, so move it onto + * the b_attached list of @new_wb. */ if (!list_empty(&inode->i_io_list)) { - struct inode *pos; - - inode_io_list_del_locked(inode, old_wb); inode->i_wb = new_wb; - list_for_each_entry(pos, &new_wb->b_dirty, i_io_list) - if (time_after_eq(inode->dirtied_when, - pos->dirtied_when)) - break; - inode_io_list_move_locked(inode, new_wb, pos->i_io_list.prev); + + if (inode->i_state & I_DIRTY_ALL) { + struct inode *pos; + + list_for_each_entry(pos, &new_wb->b_dirty, i_io_list) + if (time_after_eq(inode->dirtied_when, + pos->dirtied_when)) + break; + inode_io_list_move_locked(inode, new_wb, + pos->i_io_list.prev); + } else { + inode_cgwb_move_to_attached(inode, new_wb); + } } else { inode->i_wb = new_wb; } @@ -1014,6 +1024,12 @@ fs_initcall(cgroup_writeback_init); static void bdi_down_write_wb_switch_rwsem(struct backing_dev_info *bdi) { } static void bdi_up_write_wb_switch_rwsem(struct backing_dev_info *bdi) { } +static void inode_cgwb_move_to_attached(struct inode *inode, + struct bdi_writeback *wb) +{ + list_del_init(&inode->i_io_list); +} + static struct bdi_writeback * locked_inode_to_wb_and_lock_list(struct inode *inode) __releases(&inode->i_lock) @@ -1114,7 +1130,11 @@ void inode_io_list_del(struct inode *inode) wb = inode_to_wb_and_lock_list(inode); spin_lock(&inode->i_lock); - inode_io_list_del_locked(inode, wb); + + inode->i_state &= ~I_SYNC_QUEUED; + list_del_init(&inode->i_io_list); + wb_io_lists_depopulated(wb); + spin_unlock(&inode->i_lock); spin_unlock(&wb->list_lock); } @@ -1427,7 +1447,7 @@ static void requeue_inode(struct inode *inode, struct bdi_writeback *wb, inode->i_state &= ~I_SYNC_QUEUED; } else { /* The inode is clean. Remove from writeback lists. */ - inode_io_list_del_locked(inode, wb); + inode_cgwb_move_to_attached(inode, wb); } } @@ -1579,7 +1599,7 @@ static int writeback_single_inode(struct inode *inode, * responsible for the writeback lists. */ if (!(inode->i_state & I_DIRTY_ALL)) - inode_io_list_del_locked(inode, wb); + inode_cgwb_move_to_attached(inode, wb); spin_unlock(&wb->list_lock); inode_sync_complete(inode); out: diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h index fff9367a6348..e5dc238ebe4f 100644 --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -154,6 +154,7 @@ struct bdi_writeback { struct cgroup_subsys_state *blkcg_css; /* and blkcg */ struct list_head memcg_node; /* anchored at memcg->cgwb_list */ struct list_head blkcg_node; /* anchored at blkcg->cgwb_list */ + struct list_head b_attached; /* attached inodes, protected by list_lock */ union { struct work_struct release_work; diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 576220acd686..54c5dc4b8c24 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -396,6 +396,7 @@ static void cgwb_release_workfn(struct work_struct *work) fprop_local_destroy_percpu(&wb->memcg_completions); percpu_ref_exit(&wb->refcnt); wb_exit(wb); + WARN_ON_ONCE(!list_empty(&wb->b_attached)); kfree_rcu(wb, rcu); } @@ -472,6 +473,7 @@ static int cgwb_create(struct backing_dev_info *bdi, wb->memcg_css = memcg_css; wb->blkcg_css = blkcg_css; + INIT_LIST_HEAD(&wb->b_attached); INIT_WORK(&wb->release_work, cgwb_release_workfn); set_bit(WB_registered, &wb->state); From patchwork Thu Jun 3 00:55:15 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roman Gushchin X-Patchwork-Id: 12295945 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6F7AAC47083 for ; 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Wed, 02 Jun 2021 17:55:28 -0700 Received: from intmgw002.46.prn1.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:83::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Wed, 2 Jun 2021 17:55:27 -0700 Received: by devvm3388.prn0.facebook.com (Postfix, from userid 111017) id A09227F192A8; Wed, 2 Jun 2021 17:55:22 -0700 (PDT) From: Roman Gushchin To: Jan Kara , Tejun Heo CC: , , , Alexander Viro , Dennis Zhou , Dave Chinner , , Roman Gushchin Subject: [PATCH v6 3/5] writeback, cgroup: split out the functional part of inode_switch_wbs_work_fn() Date: Wed, 2 Jun 2021 17:55:15 -0700 Message-ID: <20210603005517.1403689-4-guro@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210603005517.1403689-1-guro@fb.com> References: <20210603005517.1403689-1-guro@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: lrh7FeBQjFBkj1WQToHnnfuxryXMFhQ1 X-Proofpoint-ORIG-GUID: lrh7FeBQjFBkj1WQToHnnfuxryXMFhQ1 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-06-02_11:2021-06-02,2021-06-02 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxscore=0 clxscore=1015 phishscore=0 spamscore=0 mlxlogscore=999 bulkscore=0 malwarescore=0 impostorscore=0 priorityscore=1501 adultscore=0 suspectscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106030004 X-FB-Internal: deliver Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=fb.com header.s=facebook header.b=mV6W9OHN; dmarc=pass (policy=reject) header.from=fb.com; spf=pass (imf27.hostedemail.com: domain of "prvs=578884e26b=guro@fb.com" designates 67.231.153.30 as permitted sender) smtp.mailfrom="prvs=578884e26b=guro@fb.com" X-Stat-Signature: jpcmxpdhgowc3wog98ixtcf1pa6xdm1k X-Rspamd-Queue-Id: BCFFA801936B X-Rspamd-Server: rspam02 X-HE-Tag: 1622681715-543588 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Split out the functional part of the inode_switch_wbs_work_fn() function as inode_do switch_wbs() to reuse it later for switching inodes attached to dying cgwbs. This commit doesn't bring any functional changes. Signed-off-by: Roman Gushchin Reviewed-by: Jan Kara --- fs/fs-writeback.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 09d2770449ef..212494d89cc2 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -351,15 +351,12 @@ static void bdi_up_write_wb_switch_rwsem(struct backing_dev_info *bdi) up_write(&bdi->wb_switch_rwsem); } -static void inode_switch_wbs_work_fn(struct work_struct *work) +static void inode_do_switch_wbs(struct inode *inode, + struct bdi_writeback *new_wb) { - struct inode_switch_wbs_context *isw = - container_of(to_rcu_work(work), struct inode_switch_wbs_context, work); - struct inode *inode = isw->inode; struct backing_dev_info *bdi = inode_to_bdi(inode); struct address_space *mapping = inode->i_mapping; struct bdi_writeback *old_wb = inode->i_wb; - struct bdi_writeback *new_wb = isw->new_wb; XA_STATE(xas, &mapping->i_pages, 0); struct page *page; bool switched = false; @@ -470,11 +467,17 @@ static void inode_switch_wbs_work_fn(struct work_struct *work) wb_wakeup(new_wb); wb_put(old_wb); } - wb_put(new_wb); +} - iput(inode); - kfree(isw); +static void inode_switch_wbs_work_fn(struct work_struct *work) +{ + struct inode_switch_wbs_context *isw = + container_of(to_rcu_work(work), struct inode_switch_wbs_context, work); + inode_do_switch_wbs(isw->inode, isw->new_wb); + wb_put(isw->new_wb); + iput(isw->inode); + kfree(isw); atomic_dec(&isw_nr_in_flight); } From patchwork Thu Jun 3 00:55:16 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roman Gushchin X-Patchwork-Id: 12295951 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE926C4708F for ; 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Wed, 02 Jun 2021 17:55:52 -0700 Received: from intmgw002.48.prn1.facebook.com (2620:10d:c085:108::8) by mail.thefacebook.com (2620:10d:c085:11d::4) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Wed, 2 Jun 2021 17:55:29 -0700 Received: by devvm3388.prn0.facebook.com (Postfix, from userid 111017) id A5C807F192AA; Wed, 2 Jun 2021 17:55:22 -0700 (PDT) From: Roman Gushchin To: Jan Kara , Tejun Heo CC: , , , Alexander Viro , Dennis Zhou , Dave Chinner , , Roman Gushchin Subject: [PATCH v6 4/5] writeback, cgroup: support switching multiple inodes at once Date: Wed, 2 Jun 2021 17:55:16 -0700 Message-ID: <20210603005517.1403689-5-guro@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210603005517.1403689-1-guro@fb.com> References: <20210603005517.1403689-1-guro@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: Xox7YRNph8jkNylZoPyfAoKWa8g1TpRq X-Proofpoint-ORIG-GUID: Xox7YRNph8jkNylZoPyfAoKWa8g1TpRq X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-06-02_11:2021-06-02,2021-06-02 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxscore=0 clxscore=1015 phishscore=0 spamscore=0 mlxlogscore=924 bulkscore=0 malwarescore=0 impostorscore=0 priorityscore=1501 adultscore=0 suspectscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106030004 X-FB-Internal: deliver X-Rspamd-Queue-Id: 61B52E00025F Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=fb.com header.s=facebook header.b=WNQRQrAb; spf=pass (imf30.hostedemail.com: domain of "prvs=578884e26b=guro@fb.com" designates 67.231.153.30 as permitted sender) smtp.mailfrom="prvs=578884e26b=guro@fb.com"; dmarc=pass (policy=reject) header.from=fb.com X-Rspamd-Server: rspam04 X-Stat-Signature: wjorjduwa3y7hsap6k6ec9k9ezfajpyd X-HE-Tag: 1622681743-714288 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Currently only a single inode can be switched to another writeback structure at once. That means to switch an inode a separate inode_switch_wbs_context structure must be allocated, and a separate rcu callback and work must be scheduled. It's fine for the existing ad-hoc switching, which is not happening that often, but sub-optimal for massive switching required in order to release a writeback structure. To prepare for it, let's add a support for switching multiple inodes at once. Instead of containing a single inode pointer, inode_switch_wbs_context will contain a NULL-terminated array of inode pointers. inode_do_switch_wbs() will be called for each inode. Signed-off-by: Roman Gushchin --- fs/fs-writeback.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 212494d89cc2..49d7b23a7cfe 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -335,10 +335,10 @@ static struct bdi_writeback *inode_to_wb_and_lock_list(struct inode *inode) } struct inode_switch_wbs_context { - struct inode *inode; - struct bdi_writeback *new_wb; - struct rcu_work work; + + struct bdi_writeback *new_wb; + struct inode *inodes[]; }; static void bdi_down_write_wb_switch_rwsem(struct backing_dev_info *bdi) @@ -473,10 +473,14 @@ static void inode_switch_wbs_work_fn(struct work_struct *work) { struct inode_switch_wbs_context *isw = container_of(to_rcu_work(work), struct inode_switch_wbs_context, work); + struct inode **inodep; + + for (inodep = &isw->inodes[0]; *inodep; inodep++) { + inode_do_switch_wbs(*inodep, isw->new_wb); + iput(*inodep); + } - inode_do_switch_wbs(isw->inode, isw->new_wb); wb_put(isw->new_wb); - iput(isw->inode); kfree(isw); atomic_dec(&isw_nr_in_flight); } @@ -503,7 +507,7 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id) if (atomic_read(&isw_nr_in_flight) > WB_FRN_MAX_IN_FLIGHT) return; - isw = kzalloc(sizeof(*isw), GFP_ATOMIC); + isw = kzalloc(sizeof(*isw) + 2 * sizeof(struct inode *), GFP_ATOMIC); if (!isw) return; @@ -528,7 +532,7 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id) __iget(inode); spin_unlock(&inode->i_lock); - isw->inode = inode; + isw->inodes[0] = inode; /* * In addition to synchronizing among switchers, I_WB_SWITCH tells From patchwork Thu Jun 3 00:55:17 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roman Gushchin X-Patchwork-Id: 12295947 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D7767C4708F for ; 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Wed, 02 Jun 2021 17:55:28 -0700 Received: from intmgw002.46.prn1.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::f) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Wed, 2 Jun 2021 17:55:27 -0700 Received: by devvm3388.prn0.facebook.com (Postfix, from userid 111017) id AB1DA7F192AC; Wed, 2 Jun 2021 17:55:22 -0700 (PDT) From: Roman Gushchin To: Jan Kara , Tejun Heo CC: , , , Alexander Viro , Dennis Zhou , Dave Chinner , , Roman Gushchin Subject: [PATCH v6 5/5] writeback, cgroup: release dying cgwbs by switching attached inodes Date: Wed, 2 Jun 2021 17:55:17 -0700 Message-ID: <20210603005517.1403689-6-guro@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210603005517.1403689-1-guro@fb.com> References: <20210603005517.1403689-1-guro@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: tflmsAuLhRhqLUpm8mN0iYwuJO94gmTz X-Proofpoint-ORIG-GUID: tflmsAuLhRhqLUpm8mN0iYwuJO94gmTz X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.761 definitions=2021-06-02_11:2021-06-02,2021-06-02 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 mlxscore=0 clxscore=1015 phishscore=0 spamscore=0 mlxlogscore=677 bulkscore=0 malwarescore=0 impostorscore=0 priorityscore=1501 adultscore=0 suspectscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106030004 X-FB-Internal: deliver X-Rspamd-Queue-Id: BEA56C00CBEB Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=fb.com header.s=facebook header.b="SYfn/GSY"; dmarc=pass (policy=reject) header.from=fb.com; spf=pass (imf14.hostedemail.com: domain of "prvs=578884e26b=guro@fb.com" designates 67.231.153.30 as permitted sender) smtp.mailfrom="prvs=578884e26b=guro@fb.com" X-Rspamd-Server: rspam03 X-Stat-Signature: q91xzobkbaqzr8swtkxqaqx9bfjt7wur X-HE-Tag: 1622681715-733704 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Asynchronously try to release dying cgwbs by switching attached inodes to the bdi's wb. It helps to get rid of per-cgroup writeback structures themselves and of pinned memory and block cgroups, which are significantly larger structures (mostly due to large per-cpu statistics data). This prevents memory waste and helps to avoid different scalability problems caused by large piles of dying cgroups. Reuse the existing mechanism of inode switching used for foreign inode detection. To speed things up batch up to 115 inode switching in a single operation (the maximum number is selected so that the resulting struct inode_switch_wbs_context can fit into 1024 bytes). Because every switching consists of two steps divided by an RCU grace period, it would be too slow without batching. Please note that the whole batch counts as a single operation (when increasing/decreasing isw_nr_in_flight). This allows to keep umounting working (flush the switching queue), however prevents cleanups from consuming the whole switching quota and effectively blocking the frn switching. A cgwb cleanup operation can fail due to different reasons (e.g. not enough memory, the cgwb has an in-flight/pending io, an attached inode in a wrong state, etc). In this case the next scheduled cleanup will make a new attempt. An attempt is made each time a new cgwb is offlined (in other words a memcg and/or a blkcg is deleted by a user). In the future an additional attempt scheduled by a timer can be implemented. Signed-off-by: Roman Gushchin --- fs/fs-writeback.c | 68 ++++++++++++++++++++++++++++++++ include/linux/backing-dev-defs.h | 1 + include/linux/writeback.h | 1 + mm/backing-dev.c | 58 ++++++++++++++++++++++++++- 4 files changed, 126 insertions(+), 2 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 49d7b23a7cfe..e8517ad677eb 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -225,6 +225,8 @@ void wb_wait_for_completion(struct wb_completion *done) /* one round can affect upto 5 slots */ #define WB_FRN_MAX_IN_FLIGHT 1024 /* don't queue too many concurrently */ +#define WB_MAX_INODES_PER_ISW 116 /* maximum inodes per isw */ + static atomic_t isw_nr_in_flight = ATOMIC_INIT(0); static struct workqueue_struct *isw_wq; @@ -552,6 +554,72 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id) kfree(isw); } +/** + * cleanup_offline_cgwb - detach associated inodes + * @wb: target wb + * + * Switch all inodes attached to @wb to the bdi's root wb in order to eventually + * release the dying @wb. Returns %true if not all inodes were switched and + * the function has to be restarted. + */ +bool cleanup_offline_cgwb(struct bdi_writeback *wb) +{ + struct inode_switch_wbs_context *isw; + struct inode *inode; + int nr; + bool restart = false; + + isw = kzalloc(sizeof(*isw) + WB_MAX_INODES_PER_ISW * + sizeof(struct inode *), GFP_KERNEL); + if (!isw) + return restart; + + /* no need to call wb_get() here: bdi's root wb is not refcounted */ + isw->new_wb = &wb->bdi->wb; + + nr = 0; + spin_lock(&wb->list_lock); + list_for_each_entry(inode, &wb->b_attached, i_io_list) { + spin_lock(&inode->i_lock); + if (!(inode->i_sb->s_flags & SB_ACTIVE) || + inode->i_state & (I_WB_SWITCH | I_FREEING) || + inode_to_wb(inode) == isw->new_wb) { + spin_unlock(&inode->i_lock); + continue; + } + inode->i_state |= I_WB_SWITCH; + __iget(inode); + spin_unlock(&inode->i_lock); + + isw->inodes[nr++] = inode; + + if (nr >= WB_MAX_INODES_PER_ISW - 1) { + restart = true; + break; + } + } + spin_unlock(&wb->list_lock); + + /* no attached inodes? bail out */ + if (nr == 0) { + kfree(isw); + return restart; + } + + /* + * In addition to synchronizing among switchers, I_WB_SWITCH tells + * the RCU protected stat update paths to grab the i_page + * lock so that stat transfer can synchronize against them. + * Let's continue after I_WB_SWITCH is guaranteed to be visible. + */ + INIT_RCU_WORK(&isw->work, inode_switch_wbs_work_fn); + queue_rcu_work(isw_wq, &isw->work); + + atomic_inc(&isw_nr_in_flight); + + return restart; +} + /** * wbc_attach_and_unlock_inode - associate wbc with target inode and unlock it * @wbc: writeback_control of interest diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h index e5dc238ebe4f..07d6b6d6dbdf 100644 --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -155,6 +155,7 @@ struct bdi_writeback { struct list_head memcg_node; /* anchored at memcg->cgwb_list */ struct list_head blkcg_node; /* anchored at blkcg->cgwb_list */ struct list_head b_attached; /* attached inodes, protected by list_lock */ + struct list_head offline_node; /* anchored at offline_cgwbs */ union { struct work_struct release_work; diff --git a/include/linux/writeback.h b/include/linux/writeback.h index 8e5c5bb16e2d..95de51c10248 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -221,6 +221,7 @@ void wbc_account_cgroup_owner(struct writeback_control *wbc, struct page *page, int cgroup_writeback_by_id(u64 bdi_id, int memcg_id, unsigned long nr_pages, enum wb_reason reason, struct wb_completion *done); void cgroup_writeback_umount(void); +bool cleanup_offline_cgwb(struct bdi_writeback *wb); /** * inode_attach_wb - associate an inode with its wb diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 54c5dc4b8c24..f1fc04412bd7 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -371,12 +371,16 @@ static void wb_exit(struct bdi_writeback *wb) #include /* - * cgwb_lock protects bdi->cgwb_tree, blkcg->cgwb_list, and memcg->cgwb_list. - * bdi->cgwb_tree is also RCU protected. + * cgwb_lock protects bdi->cgwb_tree, blkcg->cgwb_list, offline_cgwbs and + * memcg->cgwb_list. bdi->cgwb_tree is also RCU protected. */ static DEFINE_SPINLOCK(cgwb_lock); static struct workqueue_struct *cgwb_release_wq; +static LIST_HEAD(offline_cgwbs); +static void cleanup_offline_cgwbs_workfn(struct work_struct *work); +static DECLARE_WORK(cleanup_offline_cgwbs_work, cleanup_offline_cgwbs_workfn); + static void cgwb_release_workfn(struct work_struct *work) { struct bdi_writeback *wb = container_of(work, struct bdi_writeback, @@ -395,6 +399,11 @@ static void cgwb_release_workfn(struct work_struct *work) fprop_local_destroy_percpu(&wb->memcg_completions); percpu_ref_exit(&wb->refcnt); + + spin_lock_irq(&cgwb_lock); + list_del(&wb->offline_node); + spin_unlock_irq(&cgwb_lock); + wb_exit(wb); WARN_ON_ONCE(!list_empty(&wb->b_attached)); kfree_rcu(wb, rcu); @@ -414,6 +423,7 @@ static void cgwb_kill(struct bdi_writeback *wb) WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id)); list_del(&wb->memcg_node); list_del(&wb->blkcg_node); + list_add(&wb->offline_node, &offline_cgwbs); percpu_ref_kill(&wb->refcnt); } @@ -635,6 +645,48 @@ static void cgwb_bdi_unregister(struct backing_dev_info *bdi) mutex_unlock(&bdi->cgwb_release_mutex); } +/** + * cleanup_offline_cgwbs - try to release dying cgwbs + * + * Try to release dying cgwbs by switching attached inodes to the wb + * belonging to the root memory cgroup. Processed wbs are placed at the + * end of the list to guarantee the forward progress. + * + * Should be called with the acquired cgwb_lock lock, which might + * be released and re-acquired in the process. + */ +static void cleanup_offline_cgwbs_workfn(struct work_struct *work) +{ + struct bdi_writeback *wb; + LIST_HEAD(processed); + + spin_lock_irq(&cgwb_lock); + + while (!list_empty(&offline_cgwbs)) { + wb = list_first_entry(&offline_cgwbs, struct bdi_writeback, + offline_node); + list_move(&wb->offline_node, &processed); + + if (wb_has_dirty_io(wb)) + continue; + + if (!wb_tryget(wb)) + continue; + + spin_unlock_irq(&cgwb_lock); + while ((cleanup_offline_cgwb(wb))) + cond_resched(); + spin_lock_irq(&cgwb_lock); + + wb_put(wb); + } + + if (!list_empty(&processed)) + list_splice_tail(&processed, &offline_cgwbs); + + spin_unlock_irq(&cgwb_lock); +} + /** * wb_memcg_offline - kill all wb's associated with a memcg being offlined * @memcg: memcg being offlined @@ -651,6 +703,8 @@ void wb_memcg_offline(struct mem_cgroup *memcg) cgwb_kill(wb); memcg_cgwb_list->next = NULL; /* prevent new wb's */ spin_unlock_irq(&cgwb_lock); + + queue_work(system_unbound_wq, &cleanup_offline_cgwbs_work); } /**