From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C542944210C for ; Thu, 27 Aug 2026 12:25:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787833555; cv=none; b=L0PEwNKeM6W7rjD+ZucVsOBiW0LsYmPyMtCgwZxkqVhO3twtzGp/zwccQpgQsOJ4dnE21xTgzP9S3uwxA8e+eYak6QnvNZGUosE5W64QXLzajAKvOKEWkeDU321VWOEdVGHda1mCWJ9fd+JCJ+4a5f54oUANUYW5T7Y+GU+4U9E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787833555; c=relaxed/simple; bh=bBx+yV7IJJhyABE+6s6KRhMsI4Bfhep+4wemGuyC/L8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Jx/+J+auvd1iopup0t0uLoa3JW5/OcYjddqam/RBlW59F3JkCr1CckW5VEui0Gb65jMW984QdMGv0AOJsyNWwvgHcI0KMkr9s/Ns7XbtoIKr6HS0SeMFsBnN392/bMJsXwypNDirYIMGZmkzoUYLdv9VJdOMlb+IKOJWl911UG8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=C8oWJkbE; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="C8oWJkbE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B97971F000E9; Thu, 27 Aug 2026 12:25:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787833553; bh=eUeyWzt4w0SobbG2JLAydbAuwXZJy+479kyABQ2pQ/o=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=C8oWJkbEb3RtEOuC/YrC//ruTEWQTh/GE7Ao+o1jiZGyFuttuFdT2yvTKwoORQQZs ANDIdbd9S5kFWFCOUlg5yY9aCV/BS2B254/FbO2rt3XGM67CMflaega2GkKalzXjlZ 9AP7WzytinG3598cLnvWRtE/ezIBdPtdiE4UUBbrTG84qfhuEuIvMV9aD3Z0kAjZE3 UDcWwWgDA9puNaH2V57bTj+a0DlfieHPJnT/Vnsl5xdx8BWIML64Wb9WjOH+kjmU9A 1AfFVt9AFvfSmIT6fCemLts+ULy2CYEhrAf18gSdm5TM28GG+t21Ge3+iFdND75/tn pI7eLBD4SE4lg== From: Chao Yu To: jaegeuk@kernel.org Cc: linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org, Chao Yu Subject: [PATCH v4 04/12] f2fs: cache: introduce writeback thread Date: Thu, 27 Aug 2026 20:25:32 +0800 Message-ID: <20260827122541.19967-5-chao@kernel.org> X-Mailer: git-send-email 2.55.0.887.g758fc8c411-goog In-Reply-To: <20260827122541.19967-1-chao@kernel.org> References: <20260827122541.19967-1-chao@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chao Yu This patch introduces a background writeback kthread (f2fs_writeback-x:y) to periodically flush dirty metadata cache entries with a default interval of 5 seconds. It manages thread lifecycle across mount, unmount, and remount (rw/ro) transitions. It introduces a sysfs entry /sys/fs/f2fs//cache_wb_interval to control writeback interval. Signed-off-by: Chao Yu --- Documentation/ABI/testing/sysfs-fs-f2fs | 6 +++ fs/f2fs/cache.c | 56 +++++++++++++++++++++++++ fs/f2fs/cache.h | 12 ++++++ fs/f2fs/f2fs.h | 3 ++ fs/f2fs/super.c | 31 +++++++++++++- fs/f2fs/sysfs.c | 13 +++++- 6 files changed, 119 insertions(+), 2 deletions(-) diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs index 0cebc89799dd..d2665b7f1f14 100644 --- a/Documentation/ABI/testing/sysfs-fs-f2fs +++ b/Documentation/ABI/testing/sysfs-fs-f2fs @@ -1020,3 +1020,9 @@ Contact: "Daeho Jeong" Description: This is a read-only entry to show the upper bound section number for pinned files. Pinned files will only be allocated within sections 0 to pinned_area_max_secno - 1. + +What: /sys/fs/f2fs//cache_wb_interval +Date: August 2026 +Contact: "Chao Yu" +Description: This is a writable entry to control writeback interval of + f2fs_writeback-x:y, by default the value is 5000, unit is ms. diff --git a/fs/f2fs/cache.c b/fs/f2fs/cache.c index 0cb8622ef580..59cc60ad4f91 100644 --- a/fs/f2fs/cache.c +++ b/fs/f2fs/cache.c @@ -640,3 +640,59 @@ unsigned long f2fs_shrink_cache(struct f2fs_sb_info *sbi, { return f2fs_do_shrink_cache(META_CACHE(sbi), nr_to_scan); } + +static int f2fs_cache_writeback_kthread(void *data) +{ + struct f2fs_sb_info *sbi = data; + struct f2fs_cache_kthread *cache_thread = &sbi->cache_thread; + wait_queue_head_t *wq = &cache_thread->cache_wb_wq; + unsigned int interval = cache_thread->cache_wb_interval; + + set_freezable(); + + while (!kthread_should_stop()) { + wait_event_freezable_timeout(*wq, + kthread_should_stop(), + msecs_to_jiffies(interval)); + + if (kthread_should_stop()) + break; + if (f2fs_cp_error(sbi)) + continue; + } + return 0; +} + +int f2fs_start_cache_wb_thread(struct f2fs_sb_info *sbi) +{ + struct f2fs_cache_kthread *cache_thread = &sbi->cache_thread; + struct task_struct *task; + dev_t dev = sbi->sb->s_dev; + char name[36]; + + if (cache_thread->cache_wb_task) + return 0; + + init_waitqueue_head(&cache_thread->cache_wb_wq); + snprintf(name, sizeof(name), "f2fs_writeback-%u:%u", + MAJOR(dev), MINOR(dev)); + + task = kthread_run(f2fs_cache_writeback_kthread, sbi, "%s", name); + if (IS_ERR(task)) + return PTR_ERR(task); + + cache_thread->cache_wb_task = task; + cache_thread->cache_wb_interval = DEF_DIRTY_CACHE_TIMEOUT; + return 0; +} + +void f2fs_stop_cache_wb_thread(struct f2fs_sb_info *sbi) +{ + struct f2fs_cache_kthread *cache_thread = &sbi->cache_thread; + + if (!cache_thread->cache_wb_task) + return; + + kthread_stop(cache_thread->cache_wb_task); + cache_thread->cache_wb_task = NULL; +} diff --git a/fs/f2fs/cache.h b/fs/f2fs/cache.h index 5f7e74f0c873..7adab25ff3ed 100644 --- a/fs/f2fs/cache.h +++ b/fs/f2fs/cache.h @@ -194,4 +194,16 @@ void f2fs_stop_cache_wb_thread(struct f2fs_sb_info *sbi); unsigned long f2fs_shrink_cache(struct f2fs_sb_info *sbi, unsigned long nr_to_scan); +#define DEF_DIRTY_CACHE_TIMEOUT 5000 + +struct f2fs_cache_kthread { + struct task_struct *cache_wb_task; + wait_queue_head_t cache_wb_wq; + atomic_t cache_wb_trigger; + unsigned int cache_wb_interval; +}; + +int f2fs_start_cache_wb_thread(struct f2fs_sb_info *sbi); +void f2fs_stop_cache_wb_thread(struct f2fs_sb_info *sbi); + #endif /* _LINUX_F2FS_CACHE_H */ diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 0f855ac7d1e8..9fe9fadbb810 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -2111,6 +2111,9 @@ struct f2fs_sb_info { /* f2fs internal cache */ struct f2fs_cached_block_list meta_blocks; + + /* internal cache flush thread */ + struct f2fs_cache_kthread cache_thread; }; /* Definitions to access f2fs_sb_info */ diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 32e80c70e141..9bb19f4c5fd2 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -2020,6 +2020,7 @@ static void f2fs_put_super(struct super_block *sb) * flush all issued checkpoints and stop checkpoint issue thread. * after then, all checkpoints should be done by each process context. */ + f2fs_stop_cache_wb_thread(sbi); f2fs_stop_ckpt_thread(sbi); /* @@ -2826,6 +2827,7 @@ static int __f2fs_remount(struct fs_context *fc, struct super_block *sb) unsigned int flags = fc->sb_flags; int err; bool need_restart_gc = false, need_stop_gc = false; + bool need_restart_wb = false, need_stop_wb = false; bool need_restart_flush = false, need_stop_flush = false; bool need_restart_discard = false, need_stop_discard = false; bool need_enable_checkpoint = false, need_disable_checkpoint = false; @@ -2984,6 +2986,18 @@ static int __f2fs_remount(struct fs_context *fc, struct super_block *sb) need_stop_gc = true; } + if (flags & SB_RDONLY) { + if (sbi->cache_thread.cache_wb_task) { + f2fs_stop_cache_wb_thread(sbi); + need_restart_wb = true; + } + } else if (!sbi->cache_thread.cache_wb_task) { + err = f2fs_start_cache_wb_thread(sbi); + if (err) + goto restore_gc; + need_stop_wb = true; + } + if (flags & SB_RDONLY) { sync_inodes_sb(sb); @@ -3006,7 +3020,7 @@ static int __f2fs_remount(struct fs_context *fc, struct super_block *sb) } else { err = f2fs_create_flush_cmd_control(sbi); if (err) - goto restore_gc; + goto restore_wb; need_stop_flush = true; } @@ -3103,6 +3117,13 @@ static int __f2fs_remount(struct fs_context *fc, struct super_block *sb) clear_opt(sbi, FLUSH_MERGE); f2fs_destroy_flush_cmd_control(sbi, false); } +restore_wb: + if (need_restart_wb) { + if (f2fs_start_cache_wb_thread(sbi)) + f2fs_warn(sbi, "background cache writeback thread has stopped"); + } else if (need_stop_wb) { + f2fs_stop_cache_wb_thread(sbi); + } restore_gc: if (need_restart_gc) { if (f2fs_start_gc_thread(sbi)) @@ -5497,6 +5518,12 @@ static int f2fs_fill_super(struct super_block *sb, struct fs_context *fc) goto sync_free_meta; } + if (!f2fs_readonly(sb)) { + err = f2fs_start_cache_wb_thread(sbi); + if (err) + goto stop_gc_thread; + } + /* recover broken superblock */ if (recovery) { err = f2fs_commit_super(sbi, true); @@ -5519,6 +5546,8 @@ static int f2fs_fill_super(struct super_block *sb, struct fs_context *fc) sbi->umount_lock_holder = NULL; return 0; +stop_gc_thread: + f2fs_stop_gc_thread(sbi); sync_free_meta: /* safe to flush all the data */ sync_filesystem(sbi->sb); diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c index 811e350a1430..a9e8e0456ef5 100644 --- a/fs/f2fs/sysfs.c +++ b/fs/f2fs/sysfs.c @@ -40,6 +40,7 @@ enum { RESERVED_BLOCKS, /* struct f2fs_sb_info */ CPRC_INFO, /* struct ckpt_req_control */ ATGC_INFO, /* struct atgc_management */ + WB_THREAD, /* struct f2fs_cache_kthread */ }; static const char *gc_mode_names[MAX_GC_MODE] = { @@ -98,6 +99,8 @@ static unsigned char *__struct_ptr(struct f2fs_sb_info *sbi, int struct_type) return (unsigned char *)&sbi->cprc_info; else if (struct_type == ATGC_INFO) return (unsigned char *)&sbi->am; + else if (struct_type == WB_THREAD) + return (unsigned char *)&sbi->cache_thread; return NULL; } @@ -1008,7 +1011,8 @@ static ssize_t f2fs_sbi_store(struct f2fs_attr *a, bool gc_entry = (!strcmp(a->attr.name, "gc_urgent") || a->struct_type == GC_THREAD); bool thread_entry = !strcmp(a->attr.name, "ckpt_thread_ioprio") || - !strcmp(a->attr.name, "critical_task_priority"); + !strcmp(a->attr.name, "critical_task_priority") || + !strcmp(a->attr.name, "cache_wb_interval"); if (gc_entry || thread_entry) { if (!down_read_trylock(&sbi->sb->s_umount)) @@ -1218,6 +1222,9 @@ static struct f2fs_attr f2fs_attr_##name = __ATTR(name, 0444, name##_show, NULL) #define ATGC_INFO_RW_ATTR(name, elname) \ F2FS_RW_ATTR(ATGC_INFO, atgc_management, name, elname) +#define WB_THREAD_RW_ATTR(name, elname) \ + F2FS_RW_ATTR(WB_THREAD, f2fs_cache_kthread, name, elname) + /* GC_THREAD ATTR */ GC_THREAD_RW_ATTR(gc_urgent_sleep_time, urgent_sleep_time); GC_THREAD_RW_ATTR(gc_min_sleep_time, min_sleep_time); @@ -1347,6 +1354,9 @@ ATGC_INFO_RW_ATTR(atgc_candidate_count, max_candidate_count); ATGC_INFO_RW_ATTR(atgc_age_weight, age_weight); ATGC_INFO_RW_ATTR(atgc_age_threshold, age_threshold); +/* WB_THREAD ATTR */ +WB_THREAD_RW_ATTR(cache_wb_interval, cache_wb_interval); + F2FS_GENERAL_RO_ATTR(dirty_segments); F2FS_GENERAL_RO_ATTR(free_segments); F2FS_GENERAL_RO_ATTR(ovp_segments); @@ -1533,6 +1543,7 @@ static struct attribute *f2fs_attrs[] = { ATTR_LIST(lock_duration_priority), ATTR_LIST(adjust_lock_priority), ATTR_LIST(critical_task_priority), + ATTR_LIST(cache_wb_interval), NULL, }; ATTRIBUTE_GROUPS(f2fs); -- 2.49.0