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Tue, 14 Oct 2025 12:10:26 +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 04/16] writeback: affine inode to a writeback ctx within a bdi Date: Tue, 14 Oct 2025 17:38:33 +0530 Message-Id: <20251014120845.2361-5-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: 20251014121031epcas5p37b0c4e23a7ad2d623ba776498f795fb0 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: 20251014121031epcas5p37b0c4e23a7ad2d623ba776498f795fb0 References: <20251014120845.2361-1-kundan.kumar@samsung.com> X-Rspam-User: X-Rspamd-Queue-Id: 8F100160014 X-Rspamd-Server: rspam02 X-Stat-Signature: yr15phem78sw9qq9nxqbwiboyw6pkim3 X-HE-Tag: 1760443836-848628 X-HE-Meta: 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 J1C49KeN T3vImTxDM6QVSFosoEaQBs1HNJtSc6ENDG0xjbOnypNSE0Tgl/KZ3HeQ5y9lUog3ylQSCRay+9/8jde8VbV2KfN5WnqcslWhl7Pi2a+MxLU5mseT8sOTEgD+x3lhxDW+GBWBQaaC4iM7Rgtolf0F3UnyGkTkf4/ch0MDnVMEGRVoWdAqlXluRtthuwQ4qPxQWVkRG 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: Affine inode to a writeback context. This helps in minimizing the filesytem fragmentation due to inode being processed by different threads. To support parallel writeback, wire up a new superblock operation get_inode_wb_ctx(). Filesystems can override this callback and select desired writeback context for a inode. FS can use the wb context based on its geometry and also use 64 bit inode numbers. If a filesystem doesn't implement this callback, it defaults to DEFALT_WB_CTX = 0, maintaining its original behavior. An example implementation for XFS is provided, where XFS selects the writeback context based on its Allocation Group number. Signed-off-by: Anuj Gupta Signed-off-by: Kundan Kumar --- fs/fs-writeback.c | 3 ++- fs/xfs/xfs_super.c | 13 +++++++++++++ include/linux/backing-dev.h | 5 ++++- include/linux/fs.h | 1 + 4 files changed, 20 insertions(+), 2 deletions(-) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 0715a7617391..56c048e22f72 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -265,7 +265,8 @@ void __inode_attach_wb(struct inode *inode, struct folio *folio) { struct backing_dev_info *bdi = inode_to_bdi(inode); struct bdi_writeback *wb = NULL; - struct bdi_writeback_ctx *bdi_writeback_ctx = bdi->wb_ctx[0]; + struct bdi_writeback_ctx *bdi_writeback_ctx = + fetch_bdi_writeback_ctx(inode); if (inode_cgwb_enabled(inode)) { struct cgroup_subsys_state *memcg_css; diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c index bb0a82635a77..b3ec9141d902 100644 --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -53,6 +53,7 @@ #include #include #include +#include static const struct super_operations xfs_super_operations; @@ -1294,6 +1295,17 @@ xfs_fs_show_stats( return 0; } +static struct bdi_writeback_ctx * +xfs_get_inode_wb_ctx( + struct inode *inode) +{ + struct xfs_inode *ip = XFS_I(inode); + struct backing_dev_info *bdi = inode_to_bdi(inode); + xfs_agino_t agno = XFS_INO_TO_AGNO(ip->i_mount, ip->i_ino); + + return bdi->wb_ctx[agno % bdi->nr_wb_ctx]; +} + static const struct super_operations xfs_super_operations = { .alloc_inode = xfs_fs_alloc_inode, .destroy_inode = xfs_fs_destroy_inode, @@ -1310,6 +1322,7 @@ static const struct super_operations xfs_super_operations = { .free_cached_objects = xfs_fs_free_cached_objects, .shutdown = xfs_fs_shutdown, .show_stats = xfs_fs_show_stats, + .get_inode_wb_ctx = xfs_get_inode_wb_ctx, }; static int diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 951ab5497500..59bbb69d300c 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -148,6 +148,7 @@ static inline bool mapping_can_writeback(struct address_space *mapping) return inode_to_bdi(mapping->host)->capabilities & BDI_CAP_WRITEBACK; } +#define DEFAULT_WB_CTX 0 #define for_each_bdi_wb_ctx(bdi, wbctx) \ for (int __i = 0; __i < (bdi)->nr_wb_ctx \ && ((wbctx) = (bdi)->wb_ctx[__i]) != NULL; __i++) @@ -157,7 +158,9 @@ fetch_bdi_writeback_ctx(struct inode *inode) { struct backing_dev_info *bdi = inode_to_bdi(inode); - return bdi->wb_ctx[0]; + if (inode->i_sb->s_op->get_inode_wb_ctx) + return inode->i_sb->s_op->get_inode_wb_ctx(inode); + return bdi->wb_ctx[DEFAULT_WB_CTX]; } #ifdef CONFIG_CGROUP_WRITEBACK diff --git a/include/linux/fs.h b/include/linux/fs.h index 754fec84f350..5199b0d49fa5 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2379,6 +2379,7 @@ struct super_operations { */ int (*remove_bdev)(struct super_block *sb, struct block_device *bdev); void (*shutdown)(struct super_block *sb); + struct bdi_writeback_ctx *(*get_inode_wb_ctx)(struct inode *inode); }; /* -- 2.25.1