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Tue, 14 Oct 2025 12:11:22 +0000 (GMT) From: Kundan Kumar To: jaegeuk@kernel.org, chao@kernel.org, viro@zeniv.linux.org.uk, brauner@kernel.org, jack@suse.cz, miklos@szeredi.hu, agruenba@redhat.com, trondmy@kernel.org, anna@kernel.org, akpm@linux-foundation.org, willy@infradead.org, mcgrof@kernel.org, clm@meta.com, david@fromorbit.com, amir73il@gmail.com, axboe@kernel.dk, hch@lst.de, ritesh.list@gmail.com, djwong@kernel.org, dave@stgolabs.net, wangyufei@vivo.com Cc: linux-f2fs-devel@lists.sourceforge.net, linux-fsdevel@vger.kernel.org, gfs2@lists.linux.dev, linux-nfs@vger.kernel.org, linux-mm@kvack.org, gost.dev@samsung.com, kundan.kumar@samsung.com, anuj20.g@samsung.com, vishak.g@samsung.com, joshi.k@samsung.com Subject: [PATCH v2 14/16] writeback: segregated allocation and free of writeback contexts Date: Tue, 14 Oct 2025 17:38:43 +0530 Message-Id: <20251014120845.2361-15-kundan.kumar@samsung.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20251014120845.2361-1-kundan.kumar@samsung.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CMS-MailID: 20251014121126epcas5p2ff20c9139bdd702c77b9de50e4f259c7 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P cpgsPolicy: CPGSC10-542,Y X-CFilter-Loop: Reflected X-CMS-RootMailID: 20251014121126epcas5p2ff20c9139bdd702c77b9de50e4f259c7 References: <20251014120845.2361-1-kundan.kumar@samsung.com> X-Rspam-User: X-Stat-Signature: dot34a13ho1qdpe1u4cy63asjs4orko1 X-Rspamd-Queue-Id: E8E791C0002 X-Rspamd-Server: rspam09 X-HE-Tag: 1760443890-728221 X-HE-Meta: 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 2dKmmZTT l2JGJVbtywzZjFNAO1Ohh1EB7ydbgzQ1HIaq2YADnjcFApOFvM71Wpe0SzWqqSteAVgv5Jf6t5HDX+U45hbvgAfenMZTkChyEZGq27Zve771wfT9Oxp8//n1/RS/E48+pfApFKwo0q8rnhQLASgDMk5lhkgYEiKZ8HXwD 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: List-Subscribe: List-Unsubscribe: The independent functions of alloc and free will be used while changing the number of writeback contexts. Signed-off-by: Kundan Kumar Signed-off-by: Anuj Gupta --- mm/backing-dev.c | 72 ++++++++++++++++++++++++++++++++---------------- 1 file changed, 49 insertions(+), 23 deletions(-) diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 0a3204a3a3a3..2a8f3b683b2d 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -1038,8 +1038,46 @@ static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb) #endif /* CONFIG_CGROUP_WRITEBACK */ +static struct bdi_writeback_ctx **wb_ctx_alloc(struct backing_dev_info *bdi, + int num_ctxs) +{ + struct bdi_writeback_ctx **wb_ctx; + + wb_ctx = kcalloc(num_ctxs, sizeof(struct bdi_writeback_ctx *), + GFP_KERNEL); + if (!wb_ctx) + return NULL; + + for (int i = 0; i < num_ctxs; i++) { + wb_ctx[i] = (struct bdi_writeback_ctx *) + kzalloc(sizeof(struct bdi_writeback_ctx), GFP_KERNEL); + if (!wb_ctx[i]) { + pr_err("Failed to allocate %d", i); + while (--i >= 0) + kfree(wb_ctx[i]); + kfree(wb_ctx); + return NULL; + } + INIT_LIST_HEAD(&wb_ctx[i]->wb_list); + init_waitqueue_head(&wb_ctx[i]->wb_waitq); + } + return wb_ctx; +} + +static void wb_ctx_free(struct backing_dev_info *bdi) +{ + struct bdi_writeback_ctx *bdi_wb_ctx; + + for_each_bdi_wb_ctx(bdi, bdi_wb_ctx) { + kfree(bdi_wb_ctx); + } + kfree(bdi->wb_ctx); +} + int bdi_init(struct backing_dev_info *bdi) { + int ret; + bdi->dev = NULL; kref_init(&bdi->refcnt); @@ -1047,48 +1085,36 @@ int bdi_init(struct backing_dev_info *bdi) bdi->max_ratio = 100 * BDI_RATIO_SCALE; bdi->max_prop_frac = FPROP_FRAC_BASE; + INIT_LIST_HEAD(&bdi->bdi_list); + /* * User can configure nr_wb_ctx using the newly introduced sysfs knob. * echo N > /sys/class/bdi/:/nwritebacks * Filesystem can also increase same during mount. */ bdi->nr_wb_ctx = 1; - bdi->wb_ctx = kcalloc(bdi->nr_wb_ctx, - sizeof(struct bdi_writeback_ctx *), - GFP_KERNEL); - INIT_LIST_HEAD(&bdi->bdi_list); - for (int i = 0; i < bdi->nr_wb_ctx; i++) { - bdi->wb_ctx[i] = (struct bdi_writeback_ctx *) - kzalloc(sizeof(struct bdi_writeback_ctx), GFP_KERNEL); - if (!bdi->wb_ctx[i]) { - pr_err("Failed to allocate %d", i); - while (--i >= 0) - kfree(bdi->wb_ctx[i]); - kfree(bdi->wb_ctx); - return -ENOMEM; - } - INIT_LIST_HEAD(&bdi->wb_ctx[i]->wb_list); - init_waitqueue_head(&bdi->wb_ctx[i]->wb_waitq); - } + + bdi->wb_ctx = wb_ctx_alloc(bdi, bdi->nr_wb_ctx); + if (!bdi->wb_ctx) + return -ENOMEM; + bdi->last_bdp_sleep = jiffies; - return cgwb_bdi_init(bdi); + ret = cgwb_bdi_init(bdi); + if (ret) + wb_ctx_free(bdi); + return ret; } struct backing_dev_info *bdi_alloc(int node_id) { struct backing_dev_info *bdi; - struct bdi_writeback_ctx *bdi_wb_ctx; bdi = kzalloc_node(sizeof(*bdi), GFP_KERNEL, node_id); if (!bdi) return NULL; if (bdi_init(bdi)) { - for_each_bdi_wb_ctx(bdi, bdi_wb_ctx) { - kfree(bdi_wb_ctx); - } - kfree(bdi->wb_ctx); kfree(bdi); return NULL; } -- 2.25.1