From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4E020C88E45 for ; Fri, 11 Sep 2026 23:24:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.sourceforge.net; s=beta; h=Content-Transfer-Encoding:Content-Type:Cc: Reply-To:From:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Subject:MIME-Version:Message-ID:Date:To:Sender: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=ipieSDaCJpKmLmszvnOdS1ZHOb3hZqJl5AkF2ha79Ps=; b=RD0ZpZMTkqPD40BwcAvWFvdQGl 62YNUCDjIfQ6c2EhF+qND5Tp/+FDJioejnhp70nonCwMs4UUixLJUuPZVL78rMohxPJXvbkvi+whP CO93kmviF6SRnk3CnkLAkZYq6VO/3mjLlvSJ+q0eookxSkJaVit3Nyh/QW2T0q5I/qYI=; Received: from [127.0.0.1] (helo=sfs-ml-1.v29.lw.sourceforge.com) by sfs-ml-1.v29.lw.sourceforge.com with esmtp (Exim 4.95) (envelope-from ) id 1x5AbX-0006QD-6w; Fri, 11 Sep 2026 23:24:20 +0000 Received: from [172.30.29.66] (helo=mx.sourceforge.net) by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1x5AbW-0006Q6-Bp for linux-f2fs-devel@lists.sourceforge.net; Fri, 11 Sep 2026 23:24:19 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=Content-Transfer-Encoding:MIME-Version:Message-ID: Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:In-Reply-To:References:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=XXgOUPFPI5ePzxOnWQPled+IDxlIHlXzVogy/zHbBXo=; b=cIYiZhhy0y4UDsCSgZNoChIJ00 egDv0GvoszswmhiCN1ctSXxydONlrGZgfjcLrLeaD1BRvkkwk0QrAHESQ0Ti2zkm+IHsA8UKW3TFN afqEnL5A7Y+Cz8738pMssvRmGRLjBobOiRaSFwjmLl4zl/65ITN0LRo6+hX053zPpV3M=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=Content-Transfer-Encoding:MIME-Version:Message-ID:Date:Subject:Cc:To:From :Sender:Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To: References:List-Id:List-Help:List-Unsubscribe:List-Subscribe:List-Post: List-Owner:List-Archive; bh=XXgOUPFPI5ePzxOnWQPled+IDxlIHlXzVogy/zHbBXo=; b=Z psVxgFui2m+SM8I8u5ArOCeI6zzUBV8csX+Te+9AJhsVCnabRwLdu1amvTpwK2TmCO5X8NAum4OEX ewN1TjSd1Dj9jGmUoPOlkrGvBJCnsxPUCZou9GrqqOiU6VvvSareSRr0B5NuUwPSay6nAv/G+cvaC y4QJb+QNs4f1tXXc=; Received: from tor.source.kernel.org ([172.105.4.254]) by sfi-mx-1.v28.lw.sourceforge.com with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.95) id 1x5AbT-0005Sw-4C for linux-f2fs-devel@lists.sourceforge.net; Fri, 11 Sep 2026 23:24:19 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 527E260230 for ; Fri, 11 Sep 2026 23:24:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 151FC1F000FF; Fri, 11 Sep 2026 23:24:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789169053; bh=XXgOUPFPI5ePzxOnWQPled+IDxlIHlXzVogy/zHbBXo=; h=From:To:Cc:Subject:Date; b=ngVWFLWDxpzhdpvl5AMx6LSf34+c6CT+k2O+gxBsBwR3iLReWQPtQT63KNYGUC6Ko yROAoSYKxSn858cErdy+IrUeDLu9eqXmngR/CRovomL015MBNOgLGxZS/6udwaogir DnlllIxZqepIWO2iPN6jse2Gc+1XMslTisepYhG4m+lGLKNehfwXG+uq1elu1R4D5B r1wpHY2Trc/HoXFM4S6W3UEv9e35IQbmMk/j5vObfuKhw+9hWTDFqY2IaSvwf1uw3O q5FbmHiwWhX31UnJN4ZL7m+MacCnEzckwJUgm4GjclFRV5BX20RimeiZRLqxQcmyQz qVFgNmlbBjXHw== To: jaegeuk@kernel.org Date: Sat, 12 Sep 2026 07:23:53 +0800 Message-ID: <20260911232405.1815804-1-chao@kernel.org> X-Mailer: git-send-email 2.55.0.1007.g17ff1f9808-goog MIME-Version: 1.0 X-Headers-End: 1x5AbT-0005Sw-4C Subject: [f2fs-dev] [PATCH v7 00/12] f2fs: introduce metadata cache X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Chao Yu via Linux-f2fs-devel Reply-To: Chao Yu Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net This patchset introduces a self-managed metadata block cache in f2fs, decoupling meta blocks, node blocks, and compressed data blocks from the Linux VFS page cache and fake internal inodes. === 1. Background & Motivation === Currently, F2FS uses fake VFS inodes (meta_inode, node_inode, and compress_inode) to manage internal block caching through the VFS page cache. Because of this implementation, the f2fs block size was historically coupled to the kernel page size. We now want to unbind block size from page size to support configurations where block size <= PAGE_SIZE (e.g., mounting a 4KB-block F2FS image on a 16KB or 64KB page system). One possible approach is to continue using the VFS page cache to store metadata blocks. However, doing so introduces three major architectural issues (illustrated by a 4KB block on a 16KB page system): 1. Memory Overhead: Metadata access patterns are typically random and sparse. Caching a single 4KB metadata block inside a page cache folio forces the allocation of an entire 16KB folio, resulting in 4x memory waste. 2. Folio and Sub-block Conversion Complexity: Using larger folios requires tracking individual sub-block dirty/uptodate states within each folio and performing index-to-offset conversions across function boundaries. Because core metadata structures (e.g., f2fs_checkpoint, f2fs_sit_block, f2fs_nat_block, f2fs_summary_block, f2fs_node) are accessed extensively throughout the filesystem, this sub-block management and offset calculation complexity would spread across the entire F2FS codebase. 3. Lock Contention: Multiple independent node blocks (e.g., dnode blocks belonging to different files) can reside within the same folio. Concurrent fsync() calls on unrelated files would contend on the same folio_lock(), serializing metadata updates and degrading multi-threaded performance. Decoupling metadata caching from PAGE_SIZE by allocating exact block-sized cache entries is the critical first step toward supporting 4KB-block F2FS images on 16KB/64KB page systems. === 2. Metadata Cache Architecture & Design === This patchset introduces a dedicated, block-size-aligned caching infrastructure with the following key components: - Block-Size Aligned Allocation: Allocates memory buffers matching exactly the filesystem block size (4KB or 16KB) via kzalloc(), fully independent of the host architecture's PAGE_SIZE. - Radix Tree Indexing with Fast Tag Scanning: Each cache instance (META_CACHE, NODE_CACHE, COMPRESS_CACHE) indexes cached blocks via a radix tree (keyed by Physical Block Address for meta/ compress cache, and Node ID for node cache). Radix tree tags (F2FS_CACHE_TAG_DIRTY, F2FS_CACHE_TAG_WRITEBACK) provide O(1) batch gang lookups for flushing and writeback without dual-list shuffling. - Lightweight Bit-Locking: Individual entries use atomic bit locks (F2FS_BLOCK_LOCKED via wait_on_bit_lock() / clear_and_wake_up_bit()) rather than heavyweight embedded mutexes/semaphores, minimizing memory footprint per entry. - Direct BIO Read/Write & BIO Merging: Decouples metadata/node I/O from VFS address spaces by submitting direct BIOs (f2fs_submit_cache_read / f2fs_submit_cache_write) with chained adjacent vector merging (entry->next_entry) and dedicated completion handlers. - Memory Reclamation Shrinker: Integrates with the kernel shrinker subsystem via a 3-phase isolation algorithm (isolate unreferenced clean entries -> truncate from radix tree under lock -> splice un-reclaimed entries back to LRU) to safely reclaim clean cached blocks under system memory pressure. - Background Writeback Kthread & Checkpoint Integration: Provides a dedicated background kthread (f2fs_writeback-X:Y) for periodic dirty cache flushing, combined with synchronous flushing during checkpoint commit. - Fault Injection, Tracepoints & Debugfs Observability: Integrates FAULT_KALLOC fault injection, tracepoints for cache state transitions and batch writeback, and per-cache memory breakdowns in debugfs. === 3. Patchset Organization === - Patch 01: Implement the core metadata cache infrastructure & direct BIO I/O. - Patch 02: Initialize and teardown META_CACHE in sb_info. - Patch 03: Integrate metadata cache into the memory shrinker subsystem. - Patch 04: Introduce the background writeback kernel thread. - Patch 05: Migrate metadata block caching (SIT, NAT, SSA, CP, recovery, GC) from meta_inode to META_CACHE. - Patch 06: Initialize and teardown NODE_CACHE in sb_info. - Patch 07: Migrate node and inode block caching from node_inode to NODE_CACHE. - Patch 08: Initialize and teardown COMPRESS_CACHE in sb_info. - Patch 09: Migrate compressed cluster caching from compress_inode to COMPRESS_CACHE. - Patch 10: Add fault injection support for cache allocation paths. - Patch 11: Introduce ftrace tracepoints for cache dirty and writeback events. - Patch 12: Expose per-cache memory usage in debugfs. Changelog: v6->v7: - rebase on last dev-test - clean up comments, functions and macro names from page to cache/block based on Jaegeuk's patches Chao Yu (12): f2fs: cache: implement metadata cache f2fs: cache: initialize meta cache f2fs: cache: introduce shrinker f2fs: cache: introduce writeback thread f2fs: cache: use meta cache f2fs: cache: initialize node cache f2fs: cache: use node cache f2fs: cache: initialize compress cache f2fs: cache: use compress cache f2fs: cache: support fault injection f2fs: cache: introduce tracepoints f2fs: cache: show per-cache usage in debugfs Documentation/ABI/testing/sysfs-fs-f2fs | 6 + fs/f2fs/Makefile | 2 +- fs/f2fs/acl.c | 26 +- fs/f2fs/acl.h | 8 +- fs/f2fs/cache.c | 708 +++++++++++++++ fs/f2fs/cache.h | 243 +++++ fs/f2fs/checkpoint.c | 434 +++++---- fs/f2fs/compress.c | 165 ++-- fs/f2fs/data.c | 521 +++++++---- fs/f2fs/debug.c | 70 +- fs/f2fs/dir.c | 170 ++-- fs/f2fs/extent_cache.c | 14 +- fs/f2fs/f2fs.h | 376 ++++---- fs/f2fs/file.c | 82 +- fs/f2fs/gc.c | 185 ++-- fs/f2fs/inline.c | 284 +++--- fs/f2fs/inode.c | 217 ++--- fs/f2fs/iostat.h | 11 + fs/f2fs/namei.c | 114 +-- fs/f2fs/node.c | 1102 +++++++++++------------ fs/f2fs/node.h | 118 +-- fs/f2fs/recovery.c | 251 +++--- fs/f2fs/segment.c | 305 ++++--- fs/f2fs/segment.h | 37 +- fs/f2fs/shrinker.c | 14 + fs/f2fs/super.c | 147 ++- fs/f2fs/sysfs.c | 15 +- fs/f2fs/xattr.c | 123 ++- fs/f2fs/xattr.h | 12 +- include/linux/f2fs_fs.h | 3 - include/trace/events/f2fs.h | 71 ++ 31 files changed, 3511 insertions(+), 2323 deletions(-) create mode 100644 fs/f2fs/cache.c create mode 100644 fs/f2fs/cache.h -- 2.49.0 _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel