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Tue, 14 Oct 2025 12:10:14 +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 02/16] writeback: add support to initialize and free multiple writeback ctxs Date: Tue, 14 Oct 2025 17:38:31 +0530 Message-Id: <20251014120845.2361-3-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: 20251014121020epcas5p36ca8a0d6d74f7b81996bb367329feb4a 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: 20251014121020epcas5p36ca8a0d6d74f7b81996bb367329feb4a References: <20251014120845.2361-1-kundan.kumar@samsung.com> X-Rspamd-Queue-Id: 0D72C140002 X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: hdko5swudgh15hc375izbuybbyssp8yo X-HE-Tag: 1760443825-646761 X-HE-Meta: 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 HrQ31jzu +D0K2/W2CfUqwAyVR2c0EHnzS3uRWbI450hjM7CSPjGMBNAAE9h1FQgSC0ILQRnHZVTM9 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: Introduce a new macro for_each_bdi_wb_ctx to iterate over multiple writeback ctxs. Added logic for allocation, init, free, registration and unregistration of multiple writeback contexts within a bdi. Signed-off-by: Kundan Kumar Signed-off-by: Anuj Gupta --- include/linux/backing-dev.h | 4 ++ mm/backing-dev.c | 81 +++++++++++++++++++++++++++---------- 2 files changed, 63 insertions(+), 22 deletions(-) diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 92674543ac8a..951ab5497500 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -148,6 +148,10 @@ static inline bool mapping_can_writeback(struct address_space *mapping) return inode_to_bdi(mapping->host)->capabilities & BDI_CAP_WRITEBACK; } +#define for_each_bdi_wb_ctx(bdi, wbctx) \ + for (int __i = 0; __i < (bdi)->nr_wb_ctx \ + && ((wbctx) = (bdi)->wb_ctx[__i]) != NULL; __i++) + static inline struct bdi_writeback_ctx * fetch_bdi_writeback_ctx(struct inode *inode) { diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 8b7125349f6c..47196d326e16 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -835,17 +835,20 @@ struct bdi_writeback *wb_get_create(struct backing_dev_info *bdi, static int cgwb_bdi_init(struct backing_dev_info *bdi) { - int ret; - struct bdi_writeback_ctx *bdi_wb_ctx = bdi->wb_ctx[0]; + int ret = 0; + struct bdi_writeback_ctx *bdi_wb_ctx; - INIT_RADIX_TREE(&bdi_wb_ctx->cgwb_tree, GFP_ATOMIC); - mutex_init(&bdi->cgwb_release_mutex); - init_rwsem(&bdi_wb_ctx->wb_switch_rwsem); + for_each_bdi_wb_ctx(bdi, bdi_wb_ctx) { + INIT_RADIX_TREE(&bdi_wb_ctx->cgwb_tree, GFP_ATOMIC); + mutex_init(&bdi->cgwb_release_mutex); + init_rwsem(&bdi_wb_ctx->wb_switch_rwsem); - ret = wb_init(&bdi_wb_ctx->wb, bdi, GFP_KERNEL); - if (!ret) { - bdi_wb_ctx->wb.memcg_css = &root_mem_cgroup->css; - bdi_wb_ctx->wb.blkcg_css = blkcg_root_css; + ret = wb_init(&bdi_wb_ctx->wb, bdi, GFP_KERNEL); + if (!ret) { + bdi_wb_ctx->wb.memcg_css = &root_mem_cgroup->css; + bdi_wb_ctx->wb.blkcg_css = blkcg_root_css; + } else + return ret; } return ret; } @@ -992,7 +995,16 @@ subsys_initcall(cgwb_init); static int cgwb_bdi_init(struct backing_dev_info *bdi) { - return wb_init(&bdi->wb_ctx[0]->wb, bdi, GFP_KERNEL); + struct bdi_writeback_ctx *bdi_wb_ctx; + + for_each_bdi_wb_ctx(bdi, bdi_wb_ctx) { + int ret; + + ret = wb_init(&bdi_wb_ctx->wb, bdi, GFP_KERNEL); + if (ret) + return ret; + } + return 0; } static void cgwb_bdi_unregister(struct backing_dev_info *bdi, @@ -1026,10 +1038,19 @@ int bdi_init(struct backing_dev_info *bdi) sizeof(struct bdi_writeback_ctx *), GFP_KERNEL); INIT_LIST_HEAD(&bdi->bdi_list); - bdi->wb_ctx[0] = (struct bdi_writeback_ctx *) - kzalloc(sizeof(struct bdi_writeback_ctx), GFP_KERNEL); - INIT_LIST_HEAD(&bdi->wb_ctx[0]->wb_list); - init_waitqueue_head(&bdi->wb_ctx[0]->wb_waitq); + 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->last_bdp_sleep = jiffies; return cgwb_bdi_init(bdi); @@ -1038,13 +1059,16 @@ int bdi_init(struct backing_dev_info *bdi) 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)) { - kfree(bdi->wb_ctx[0]); + for_each_bdi_wb_ctx(bdi, bdi_wb_ctx) { + kfree(bdi_wb_ctx); + } kfree(bdi->wb_ctx); kfree(bdi); return NULL; @@ -1109,6 +1133,7 @@ int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args) { struct device *dev; struct rb_node *parent, **p; + struct bdi_writeback_ctx *bdi_wb_ctx; if (bdi->dev) /* The driver needs to use separate queues per device */ return 0; @@ -1118,8 +1143,11 @@ int bdi_register_va(struct backing_dev_info *bdi, const char *fmt, va_list args) if (IS_ERR(dev)) return PTR_ERR(dev); - cgwb_bdi_register(bdi, bdi->wb_ctx[0]); - set_bit(WB_registered, &bdi->wb_ctx[0]->wb.state); + for_each_bdi_wb_ctx(bdi, bdi_wb_ctx) { + cgwb_bdi_register(bdi, bdi_wb_ctx); + set_bit(WB_registered, &bdi_wb_ctx->wb.state); + } + bdi->dev = dev; bdi_debug_register(bdi, dev_name(dev)); @@ -1174,12 +1202,17 @@ static void bdi_remove_from_list(struct backing_dev_info *bdi) void bdi_unregister(struct backing_dev_info *bdi) { + struct bdi_writeback_ctx *bdi_wb_ctx; + timer_delete_sync(&bdi->laptop_mode_wb_timer); /* make sure nobody finds us on the bdi_list anymore */ bdi_remove_from_list(bdi); - wb_shutdown(&bdi->wb_ctx[0]->wb); - cgwb_bdi_unregister(bdi, bdi->wb_ctx[0]); + + for_each_bdi_wb_ctx(bdi, bdi_wb_ctx) { + wb_shutdown(&bdi_wb_ctx->wb); + cgwb_bdi_unregister(bdi, bdi_wb_ctx); + } /* * If this BDI's min ratio has been set, use bdi_set_min_ratio() to @@ -1205,11 +1238,15 @@ static void release_bdi(struct kref *ref) { struct backing_dev_info *bdi = container_of(ref, struct backing_dev_info, refcnt); + struct bdi_writeback_ctx *bdi_wb_ctx; WARN_ON_ONCE(bdi->dev); - WARN_ON_ONCE(test_bit(WB_registered, &bdi->wb_ctx[0]->wb.state)); - wb_exit(&bdi->wb_ctx[0]->wb); - kfree(bdi->wb_ctx[0]); + + for_each_bdi_wb_ctx(bdi, bdi_wb_ctx) { + WARN_ON_ONCE(test_bit(WB_registered, &bdi_wb_ctx->wb.state)); + wb_exit(&bdi_wb_ctx->wb); + kfree(bdi_wb_ctx); + } kfree(bdi->wb_ctx); kfree(bdi); } -- 2.25.1