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* [PATCH] f2fs: embed f2fs_gc_kthread in f2fs_sb_info
@ 2026-06-29 13:11 ` Chao Yu via Linux-f2fs-devel
  0 siblings, 0 replies; 2+ messages in thread
From: Chao Yu @ 2026-06-29 13:11 UTC (permalink / raw)
  To: jaegeuk; +Cc: linux-f2fs-devel, linux-kernel, Chao Yu, stable

Instead of allocating f2fs_gc_kthread dynamically, embed it in
f2fs_sb_info. This simplifies lifetime management and prepares for
fixing race conditions during teardown.

- __sbi_store			- remount|shutdown
				 - f2fs_stop_gc_thread
 - access sbi->gc_thread
				  - sbi->gc_thread = NULL
 - access sbi->gc_thread->f2fs_gc_task

Fixes: 52190933c37a ("f2fs: sysfs: introduce critical_task_priority")
Fixes: 7950e9ac638e ("f2fs: stop gc/discard thread after fs shutdown")
Cc: stable@kernel.org
Signed-off-by: Chao Yu <chao@kernel.org>
---
 fs/f2fs/debug.c   |  4 ----
 fs/f2fs/f2fs.h    | 29 ++++++++++++++++++++++++++++-
 fs/f2fs/gc.c      | 35 +++++++++++++----------------------
 fs/f2fs/gc.h      | 27 +--------------------------
 fs/f2fs/segment.c |  9 ++++-----
 fs/f2fs/super.c   |  4 ++--
 fs/f2fs/sysfs.c   | 22 +++++++++++-----------
 7 files changed, 59 insertions(+), 71 deletions(-)

diff --git a/fs/f2fs/debug.c b/fs/f2fs/debug.c
index af88db8fdb71..ff379aff4472 100644
--- a/fs/f2fs/debug.c
+++ b/fs/f2fs/debug.c
@@ -352,10 +352,6 @@ static void update_mem_info(struct f2fs_sb_info *sbi)
 get_cache:
 	si->cache_mem = 0;
 
-	/* build gc */
-	if (sbi->gc_thread)
-		si->cache_mem += sizeof(struct f2fs_gc_kthread);
-
 	/* build merge flush thread */
 	if (SM_I(sbi)->fcc_info)
 		si->cache_mem += sizeof(struct flush_cmd_control);
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index d1da8e8afca3..d662f6d282d5 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1761,6 +1761,33 @@ struct decompress_io_ctx {
 #define MAX_COMPRESS_LOG_SIZE		8
 #define MAX_COMPRESS_WINDOW_SIZE(log_size)	((PAGE_SIZE) << (log_size))
 
+struct f2fs_gc_kthread {
+	struct task_struct *f2fs_gc_task;
+	wait_queue_head_t gc_wait_queue_head;
+
+	/* for gc sleep time */
+	unsigned int urgent_sleep_time;
+	unsigned int min_sleep_time;
+	unsigned int max_sleep_time;
+	unsigned int no_gc_sleep_time;
+
+	/* for changing gc mode */
+	bool gc_wake;
+
+	/* for GC_MERGE mount option */
+	wait_queue_head_t fggc_wq;		/*
+						 * caller of f2fs_balance_fs()
+						 * will wait on this wait queue.
+						 */
+
+	/* for gc control for zoned devices */
+	unsigned int no_zoned_gc_percent;
+	unsigned int boost_zoned_gc_percent;
+	unsigned int valid_thresh_ratio;
+	unsigned int boost_gc_multiple;
+	unsigned int boost_gc_greedy;
+};
+
 struct f2fs_sb_info {
 	struct super_block *sb;			/* pointer to VFS super block */
 	struct proc_dir_entry *s_proc;		/* proc entry */
@@ -1898,7 +1925,7 @@ struct f2fs_sb_info {
 						 * semaphore for GC, avoid
 						 * race between GC and GC or CP
 						 */
-	struct f2fs_gc_kthread	*gc_thread;	/* GC thread */
+	struct f2fs_gc_kthread gc_thread;	/* GC thread */
 	struct atgc_management am;		/* atgc management */
 	unsigned int cur_victim_sec;		/* current victim section num */
 	unsigned int gc_mode;			/* current GC state */
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 287ced326253..bf3d9e460ec1 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -31,9 +31,9 @@ static unsigned int count_bits(const unsigned long *addr,
 static int gc_thread_func(void *data)
 {
 	struct f2fs_sb_info *sbi = data;
-	struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
-	wait_queue_head_t *wq = &sbi->gc_thread->gc_wait_queue_head;
-	wait_queue_head_t *fggc_wq = &sbi->gc_thread->fggc_wq;
+	struct f2fs_gc_kthread *gc_th = &sbi->gc_thread;
+	wait_queue_head_t *wq = &sbi->gc_thread.gc_wait_queue_head;
+	wait_queue_head_t *fggc_wq = &sbi->gc_thread.fggc_wq;
 	unsigned int wait_ms;
 	struct f2fs_gc_control gc_control = {
 		.victim_segno = NULL_SEGNO,
@@ -193,13 +193,9 @@ static int gc_thread_func(void *data)
 
 int f2fs_start_gc_thread(struct f2fs_sb_info *sbi)
 {
-	struct f2fs_gc_kthread *gc_th;
+	struct f2fs_gc_kthread *gc_th = &sbi->gc_thread;
 	dev_t dev = sbi->sb->s_bdev->bd_dev;
 
-	gc_th = f2fs_kmalloc(sbi, sizeof(struct f2fs_gc_kthread), GFP_KERNEL);
-	if (!gc_th)
-		return -ENOMEM;
-
 	gc_th->urgent_sleep_time = DEF_GC_THREAD_URGENT_SLEEP_TIME;
 	gc_th->valid_thresh_ratio = DEF_GC_THREAD_VALID_THRESH_RATIO;
 	gc_th->boost_gc_multiple = BOOST_GC_MULTIPLE;
@@ -221,16 +217,14 @@ int f2fs_start_gc_thread(struct f2fs_sb_info *sbi)
 
 	gc_th->gc_wake = false;
 
-	sbi->gc_thread = gc_th;
-	init_waitqueue_head(&sbi->gc_thread->gc_wait_queue_head);
-	init_waitqueue_head(&sbi->gc_thread->fggc_wq);
-	sbi->gc_thread->f2fs_gc_task = kthread_run(gc_thread_func, sbi,
+	init_waitqueue_head(&gc_th->gc_wait_queue_head);
+	init_waitqueue_head(&gc_th->fggc_wq);
+	gc_th->f2fs_gc_task = kthread_run(gc_thread_func, sbi,
 			"f2fs_gc-%u:%u", MAJOR(dev), MINOR(dev));
 	if (IS_ERR(gc_th->f2fs_gc_task)) {
 		int err = PTR_ERR(gc_th->f2fs_gc_task);
 
-		kfree(gc_th);
-		sbi->gc_thread = NULL;
+		gc_th->f2fs_gc_task = NULL;
 		return err;
 	}
 
@@ -241,14 +235,11 @@ int f2fs_start_gc_thread(struct f2fs_sb_info *sbi)
 
 void f2fs_stop_gc_thread(struct f2fs_sb_info *sbi)
 {
-	struct f2fs_gc_kthread *gc_th = sbi->gc_thread;
+	struct f2fs_gc_kthread *gc_th = &sbi->gc_thread;
 
-	if (!gc_th)
-		return;
 	kthread_stop(gc_th->f2fs_gc_task);
+	gc_th->f2fs_gc_task = NULL;
 	wake_up_all(&gc_th->fggc_wq);
-	kfree(gc_th);
-	sbi->gc_thread = NULL;
 }
 
 static int select_gc_type(struct f2fs_sb_info *sbi, int gc_type)
@@ -796,7 +787,7 @@ int f2fs_get_victim(struct f2fs_sb_info *sbi, unsigned int *result,
 	if (one_time) {
 		p.one_time_gc = one_time;
 		if (has_enough_free_secs(sbi, 0, NR_PERSISTENT_LOG))
-			valid_thresh_ratio = sbi->gc_thread->valid_thresh_ratio;
+			valid_thresh_ratio = sbi->gc_thread.valid_thresh_ratio;
 	}
 
 retry:
@@ -1807,9 +1798,9 @@ static int do_garbage_collect(struct f2fs_sb_info *sbi,
 
 			if (f2fs_sb_has_blkzoned(sbi) &&
 					!has_enough_free_blocks(sbi,
-					sbi->gc_thread->boost_zoned_gc_percent))
+					sbi->gc_thread.boost_zoned_gc_percent))
 				window_granularity *=
-					sbi->gc_thread->boost_gc_multiple;
+					sbi->gc_thread.boost_gc_multiple;
 
 			end_segno = start_segno + window_granularity;
 		}
diff --git a/fs/f2fs/gc.h b/fs/f2fs/gc.h
index 6c4d4567571e..b015742fb455 100644
--- a/fs/f2fs/gc.h
+++ b/fs/f2fs/gc.h
@@ -45,32 +45,7 @@
 
 #define NR_GC_CHECKPOINT_SECS (3)	/* data/node/dentry sections */
 
-struct f2fs_gc_kthread {
-	struct task_struct *f2fs_gc_task;
-	wait_queue_head_t gc_wait_queue_head;
-
-	/* for gc sleep time */
-	unsigned int urgent_sleep_time;
-	unsigned int min_sleep_time;
-	unsigned int max_sleep_time;
-	unsigned int no_gc_sleep_time;
-
-	/* for changing gc mode */
-	bool gc_wake;
-
-	/* for GC_MERGE mount option */
-	wait_queue_head_t fggc_wq;		/*
-						 * caller of f2fs_balance_fs()
-						 * will wait on this wait queue.
-						 */
 
-	/* for gc control for zoned devices */
-	unsigned int no_zoned_gc_percent;
-	unsigned int boost_zoned_gc_percent;
-	unsigned int valid_thresh_ratio;
-	unsigned int boost_gc_multiple;
-	unsigned int boost_gc_greedy;
-};
 
 struct gc_inode_list {
 	struct list_head ilist;
@@ -197,6 +172,6 @@ static inline bool need_to_boost_gc(struct f2fs_sb_info *sbi)
 {
 	if (f2fs_sb_has_blkzoned(sbi))
 		return !has_enough_free_blocks(sbi,
-				sbi->gc_thread->boost_zoned_gc_percent);
+				sbi->gc_thread.boost_zoned_gc_percent);
 	return has_enough_invalid_blocks(sbi);
 }
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 70944f9dd6c5..dae5bfe87dc4 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -452,15 +452,14 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need)
 	f2fs_submit_merged_write(sbi, DATA);
 	f2fs_submit_all_merged_ipu_writes(sbi);
 
-	if (test_opt(sbi, GC_MERGE) && sbi->gc_thread &&
-				sbi->gc_thread->f2fs_gc_task) {
+	if (test_opt(sbi, GC_MERGE) && sbi->gc_thread.f2fs_gc_task) {
 		DEFINE_WAIT(wait);
 
-		prepare_to_wait(&sbi->gc_thread->fggc_wq, &wait,
+		prepare_to_wait(&sbi->gc_thread.fggc_wq, &wait,
 					TASK_UNINTERRUPTIBLE);
-		wake_up(&sbi->gc_thread->gc_wait_queue_head);
+		wake_up(&sbi->gc_thread.gc_wait_queue_head);
 		io_schedule();
-		finish_wait(&sbi->gc_thread->fggc_wq, &wait);
+		finish_wait(&sbi->gc_thread.fggc_wq, &wait);
 	} else {
 		struct f2fs_gc_control gc_control = {
 			.victim_segno = NULL_SEGNO,
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index fa04325717de..d789aa8644b6 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2954,11 +2954,11 @@ static int __f2fs_remount(struct fs_context *fc, struct super_block *sb)
 	if ((flags & SB_RDONLY) ||
 			(F2FS_OPTION(sbi).bggc_mode == BGGC_MODE_OFF &&
 			!test_opt(sbi, GC_MERGE))) {
-		if (sbi->gc_thread) {
+		if (sbi->gc_thread.f2fs_gc_task) {
 			f2fs_stop_gc_thread(sbi);
 			need_restart_gc = true;
 		}
-	} else if (!sbi->gc_thread) {
+	} else if (!sbi->gc_thread.f2fs_gc_task) {
 		err = f2fs_start_gc_thread(sbi);
 		if (err)
 			goto restore_opts;
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 47b378ccf07a..d9f81edca04a 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -75,7 +75,7 @@ static ssize_t f2fs_sbi_show(struct f2fs_attr *a,
 static unsigned char *__struct_ptr(struct f2fs_sb_info *sbi, int struct_type)
 {
 	if (struct_type == GC_THREAD)
-		return (unsigned char *)sbi->gc_thread;
+		return (unsigned char *)&sbi->gc_thread;
 	else if (struct_type == SM_INFO)
 		return (unsigned char *)SM_I(sbi);
 	else if (struct_type == DCC_INFO)
@@ -664,20 +664,20 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
 			sbi->gc_mode = GC_NORMAL;
 		} else if (t == 1) {
 			sbi->gc_mode = GC_URGENT_HIGH;
-			if (sbi->gc_thread) {
-				sbi->gc_thread->gc_wake = true;
+			if (sbi->gc_thread.f2fs_gc_task) {
+				sbi->gc_thread.gc_wake = true;
 				wake_up_interruptible_all(
-					&sbi->gc_thread->gc_wait_queue_head);
+					&sbi->gc_thread.gc_wait_queue_head);
 				wake_up_discard_thread(sbi, true);
 			}
 		} else if (t == 2) {
 			sbi->gc_mode = GC_URGENT_LOW;
 		} else if (t == 3) {
 			sbi->gc_mode = GC_URGENT_MID;
-			if (sbi->gc_thread) {
-				sbi->gc_thread->gc_wake = true;
+			if (sbi->gc_thread.f2fs_gc_task) {
+				sbi->gc_thread.gc_wake = true;
 				wake_up_interruptible_all(
-					&sbi->gc_thread->gc_wait_queue_head);
+					&sbi->gc_thread.gc_wait_queue_head);
 			}
 		} else {
 			return -EINVAL;
@@ -934,14 +934,14 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
 	if (!strcmp(a->attr.name, "gc_boost_gc_multiple")) {
 		if (t < 1 || t > SEGS_PER_SEC(sbi))
 			return -EINVAL;
-		sbi->gc_thread->boost_gc_multiple = (unsigned int)t;
+		sbi->gc_thread.boost_gc_multiple = (unsigned int)t;
 		return count;
 	}
 
 	if (!strcmp(a->attr.name, "gc_boost_gc_greedy")) {
 		if (t > GC_GREEDY)
 			return -EINVAL;
-		sbi->gc_thread->boost_gc_greedy = (unsigned int)t;
+		sbi->gc_thread.boost_gc_greedy = (unsigned int)t;
 		return count;
 	}
 
@@ -989,8 +989,8 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
 		if (sbi->cprc_info.f2fs_issue_ckpt)
 			set_user_nice(sbi->cprc_info.f2fs_issue_ckpt,
 					PRIO_TO_NICE(sbi->critical_task_priority));
-		if (sbi->gc_thread && sbi->gc_thread->f2fs_gc_task)
-			set_user_nice(sbi->gc_thread->f2fs_gc_task,
+		if (sbi->gc_thread.f2fs_gc_task)
+			set_user_nice(sbi->gc_thread.f2fs_gc_task,
 					PRIO_TO_NICE(sbi->critical_task_priority));
 		return count;
 	}
-- 
2.49.0


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2026-06-29 13:11 [PATCH] f2fs: embed f2fs_gc_kthread in f2fs_sb_info Chao Yu
2026-06-29 13:11 ` [f2fs-dev] " Chao Yu via Linux-f2fs-devel

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