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Message-Id: <20260204030501.85441-1-chao@kernel.org>
Date: Wed, 4 Feb 2026 11:05:01 +0800
From: Chao Yu <chao@...nel.org>
To: jaegeuk@...nel.org
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org,
Chao Yu <chao@...nel.org>
Subject: [PATCH] f2fs: sysfs: introduce critical_task_priority
This patch introduces /sys/fs/f2fs/<disk>/critical_task_priority, w/
this new sysfs interface, we can tune priority of f2fs_ckpt thread and
f2fs_gc thread.
Signed-off-by: Chao Yu <chao@...nel.org>
---
Documentation/ABI/testing/sysfs-fs-f2fs | 8 ++++++++
fs/f2fs/checkpoint.c | 2 ++
fs/f2fs/f2fs.h | 4 ++++
fs/f2fs/gc.c | 2 ++
fs/f2fs/super.c | 1 +
fs/f2fs/sysfs.c | 17 +++++++++++++++++
6 files changed, 34 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index ea6474db8a31..c1d2b3fd9c65 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -987,3 +987,11 @@ Contact: "Chao Yu" <chao@...nel.org>
Description: f2fs can tune priority of thread which has entered into critical region covered by
f2fs rwsemphore lock. This sysfs entry can be used to control priority value, the
range is [100,139], by default the value is 120.
+
+What: /sys/fs/f2fs/<disk>/critical_task_priority
+Date: February 2026
+Contact: "Chao Yu" <chao@...nel.org>
+Description: It can be used to tune priority of f2fs critical task, e.g. f2fs_ckpt, f2fs_gc
+ threads, limitation as below:
+ - it requires user has CAP_SYS_NICE capability.
+ - the range is [100, 139], by default the value is 100.
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index 4afa5d9a19fc..6dd39b7de11a 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -2158,6 +2158,8 @@ int f2fs_start_ckpt_thread(struct f2fs_sb_info *sbi)
}
set_task_ioprio(cprc->f2fs_issue_ckpt, cprc->ckpt_thread_ioprio);
+ set_user_nice(cprc->f2fs_issue_ckpt,
+ PRIO_TO_NICE(sbi->critical_task_priority));
return 0;
}
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index a6e7368fc40a..aa0bca9f851d 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1593,6 +1593,7 @@ enum node_type {
#define MAX_LOCK_ELAPSED_TIME 500
#define F2FS_DEFAULT_TASK_PRIORITY (DEFAULT_PRIO)
+#define F2FS_CRITICAL_TASK_PRIORITY NICE_TO_PRIO(0)
static inline int f2fs_test_bit(unsigned int nr, char *addr);
static inline void f2fs_set_bit(unsigned int nr, char *addr);
@@ -2010,6 +2011,9 @@ struct f2fs_sb_info {
/* adjust priority for task which is in critical region covered by lock */
unsigned int lock_duration_priority;
+ /* priority for critical task, e.g. f2fs_ckpt, f2fs_gc threads */
+ long critical_task_priority;
+
#ifdef CONFIG_F2FS_FS_COMPRESSION
struct kmem_cache *page_array_slab; /* page array entry */
unsigned int page_array_slab_size; /* default page array slab size */
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 60378614bc54..f46b2673d31f 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -234,6 +234,8 @@ int f2fs_start_gc_thread(struct f2fs_sb_info *sbi)
return err;
}
+ set_user_nice(gc_th->f2fs_gc_task,
+ PRIO_TO_NICE(sbi->critical_task_priority));
return 0;
}
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index d5cf7265e5d3..1a755997aff5 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -4340,6 +4340,7 @@ static void init_sb_info(struct f2fs_sb_info *sbi)
sbi->max_lock_elapsed_time = MAX_LOCK_ELAPSED_TIME;
sbi->adjust_lock_priority = 0;
sbi->lock_duration_priority = F2FS_DEFAULT_TASK_PRIORITY;
+ sbi->critical_task_priority = F2FS_CRITICAL_TASK_PRIORITY;
sbi->sum_blocksize = f2fs_sb_has_packed_ssa(sbi) ?
4096 : sbi->blocksize;
diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 3a272e7edf23..5fbfdc96e502 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -969,6 +969,21 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
return count;
}
+ if (!strcmp(a->attr.name, "critical_task_priority")) {
+ if (t < NICE_TO_PRIO(MIN_NICE) || t > NICE_TO_PRIO(MAX_NICE))
+ return -EINVAL;
+ if (!capable(CAP_SYS_NICE))
+ return -EPERM;
+ sbi->critical_task_priority = t;
+ 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,
+ PRIO_TO_NICE(sbi->critical_task_priority));
+ return count;
+ }
+
__sbi_store_value(a, sbi, ptr + a->offset, t);
return count;
@@ -1288,6 +1303,7 @@ F2FS_SBI_GENERAL_RW_ATTR(bggc_io_aware);
F2FS_SBI_GENERAL_RW_ATTR(max_lock_elapsed_time);
F2FS_SBI_GENERAL_RW_ATTR(lock_duration_priority);
F2FS_SBI_GENERAL_RW_ATTR(adjust_lock_priority);
+F2FS_SBI_GENERAL_RW_ATTR(critical_task_priority);
/* STAT_INFO ATTR */
#ifdef CONFIG_F2FS_STAT_FS
@@ -1496,6 +1512,7 @@ static struct attribute *f2fs_attrs[] = {
ATTR_LIST(max_lock_elapsed_time),
ATTR_LIST(lock_duration_priority),
ATTR_LIST(adjust_lock_priority),
+ ATTR_LIST(critical_task_priority),
NULL,
};
ATTRIBUTE_GROUPS(f2fs);
--
2.40.1
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