From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754145AbdLFA7E (ORCPT ); Tue, 5 Dec 2017 19:59:04 -0500 Received: from bombadil.infradead.org ([65.50.211.133]:59532 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753330AbdLFAmL (ORCPT ); Tue, 5 Dec 2017 19:42:11 -0500 From: Matthew Wilcox Cc: Matthew Wilcox , Ross Zwisler , Jens Axboe , Rehas Sachdeva , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-nilfs@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 34/73] mm: Convert cgroup writeback to XArray Date: Tue, 5 Dec 2017 16:41:20 -0800 Message-Id: <20171206004159.3755-35-willy@infradead.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20171206004159.3755-1-willy@infradead.org> References: <20171206004159.3755-1-willy@infradead.org> To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Matthew Wilcox This is a fairly naive conversion, leaving in place the GFP_ATOMIC allocation. By switching the locking around, we could use GFP_KERNEL and probably simplify the error handling. Signed-off-by: Matthew Wilcox --- include/linux/backing-dev-defs.h | 2 +- include/linux/backing-dev.h | 2 +- mm/backing-dev.c | 28 ++++++++++++++++------------ 3 files changed, 18 insertions(+), 14 deletions(-) diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h index bfe86b54f6c1..074a54aad33c 100644 --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -187,7 +187,7 @@ struct backing_dev_info { struct bdi_writeback wb; /* the root writeback info for this bdi */ struct list_head wb_list; /* list of all wbs */ #ifdef CONFIG_CGROUP_WRITEBACK - struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */ + struct xarray cgwb_xa; /* radix tree of active cgroup wbs */ struct rb_root cgwb_congested_tree; /* their congested states */ #else struct bdi_writeback_congested *wb_congested; diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 9038f6c1eeda..50f666d23527 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -271,7 +271,7 @@ static inline struct bdi_writeback *wb_find_current(struct backing_dev_info *bdi if (!memcg_css->parent) return &bdi->wb; - wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); + wb = xa_load(&bdi->cgwb_xa, memcg_css->id); /* * %current's blkcg equals the effective blkcg of its memcg. No diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 84b2dc76f140..7aa2d893f929 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -417,8 +417,8 @@ static void wb_exit(struct bdi_writeback *wb) #include /* - * cgwb_lock protects bdi->cgwb_tree, bdi->cgwb_congested_tree, - * blkcg->cgwb_list, and memcg->cgwb_list. bdi->cgwb_tree is also RCU + * cgwb_lock protects bdi->cgwb_xa, bdi->cgwb_congested_tree, + * blkcg->cgwb_list, and memcg->cgwb_list. bdi->cgwb_xa is also RCU * protected. */ static DEFINE_SPINLOCK(cgwb_lock); @@ -539,7 +539,7 @@ static void cgwb_kill(struct bdi_writeback *wb) { lockdep_assert_held(&cgwb_lock); - WARN_ON(!radix_tree_delete(&wb->bdi->cgwb_tree, wb->memcg_css->id)); + WARN_ON(xa_erase(&wb->bdi->cgwb_xa, wb->memcg_css->id) != wb); list_del(&wb->memcg_node); list_del(&wb->blkcg_node); percpu_ref_kill(&wb->refcnt); @@ -571,7 +571,7 @@ static int cgwb_create(struct backing_dev_info *bdi, /* look up again under lock and discard on blkcg mismatch */ spin_lock_irqsave(&cgwb_lock, flags); - wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); + wb = xa_load(&bdi->cgwb_xa, memcg_css->id); if (wb && wb->blkcg_css != blkcg_css) { cgwb_kill(wb); wb = NULL; @@ -615,13 +615,18 @@ static int cgwb_create(struct backing_dev_info *bdi, if (test_bit(WB_registered, &bdi->wb.state) && blkcg_cgwb_list->next && memcg_cgwb_list->next) { /* we might have raced another instance of this function */ - ret = radix_tree_insert(&bdi->cgwb_tree, memcg_css->id, wb); - if (!ret) { + void *curr = xa_cmpxchg(&bdi->cgwb_xa, memcg_css->id, NULL, + wb, GFP_ATOMIC); + if (!curr) { list_add_tail_rcu(&wb->bdi_node, &bdi->wb_list); list_add(&wb->memcg_node, memcg_cgwb_list); list_add(&wb->blkcg_node, blkcg_cgwb_list); css_get(memcg_css); css_get(blkcg_css); + } else if (IS_ERR(curr)) { + ret = PTR_ERR(curr); + } else { + ret = -EEXIST; } } spin_unlock_irqrestore(&cgwb_lock, flags); @@ -682,7 +687,7 @@ struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, do { rcu_read_lock(); - wb = radix_tree_lookup(&bdi->cgwb_tree, memcg_css->id); + wb = xa_load(&bdi->cgwb_xa, memcg_css->id); if (wb) { struct cgroup_subsys_state *blkcg_css; @@ -704,7 +709,7 @@ static int cgwb_bdi_init(struct backing_dev_info *bdi) { int ret; - INIT_RADIX_TREE(&bdi->cgwb_tree, GFP_ATOMIC); + xa_init(&bdi->cgwb_xa); bdi->cgwb_congested_tree = RB_ROOT; ret = wb_init(&bdi->wb, bdi, 1, GFP_KERNEL); @@ -717,15 +722,14 @@ static int cgwb_bdi_init(struct backing_dev_info *bdi) static void cgwb_bdi_unregister(struct backing_dev_info *bdi) { - struct radix_tree_iter iter; - void **slot; + XA_STATE(xas, &bdi->cgwb_xa, 0); struct bdi_writeback *wb; WARN_ON(test_bit(WB_registered, &bdi->wb.state)); spin_lock_irq(&cgwb_lock); - radix_tree_for_each_slot(slot, &bdi->cgwb_tree, &iter, 0) - cgwb_kill(*slot); + xas_for_each(&xas, wb, ULONG_MAX) + cgwb_kill(wb); while (!list_empty(&bdi->wb_list)) { wb = list_first_entry(&bdi->wb_list, struct bdi_writeback, -- 2.15.0