* [PATCH] f2fs: introduce flush_policy sysfs entry
@ 2025-07-31 8:47 Chao Yu
2025-08-07 2:16 ` [f2fs-dev] " Zhiguo Niu
0 siblings, 1 reply; 3+ messages in thread
From: Chao Yu @ 2025-07-31 8:47 UTC (permalink / raw)
To: jaegeuk; +Cc: linux-f2fs-devel, linux-kernel, Chao Yu
This patch introduces a new sysfs entry /sys/fs/f2fs/<disk>/flush_policy
in order to tune performance of f2fs data flush flow.
For example, checkpoint will use REQ_FUA to persist CP metadata, however,
some kind device has bad performance on REQ_FUA command, result in that
checkpoint being blocked for long time, w/ this sysfs entry, we can give
an option to use REQ_PREFLUSH command instead of REQ_FUA during checkpoint,
it can help to mitigate long latency of checkpoint.
Signed-off-by: Chao Yu <chao@kernel.org>
---
Documentation/ABI/testing/sysfs-fs-f2fs | 9 +++++++++
fs/f2fs/checkpoint.c | 10 +++++++++-
fs/f2fs/f2fs.h | 7 +++++++
fs/f2fs/sysfs.c | 9 +++++++++
4 files changed, 34 insertions(+), 1 deletion(-)
diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index bc0e7fefc39d..2fedb44b713b 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -883,3 +883,12 @@ Date: June 2025
Contact: "Daeho Jeong" <daehojeong@google.com>
Description: Control GC algorithm for boost GC. 0: cost benefit, 1: greedy
Default: 1
+
+What: /sys/fs/f2fs/<disk>/flush_policy
+Date: July 2025
+Contact: "Chao Yu" <chao@kernel.org>
+Description: Device has different performance for the same flush methods, this node
+ can be used to tune performance by setting different flush methods.
+
+ policy value description
+ 0x00000001 Use preflush instead of fua during checkpoint
diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
index bbe07e3a6c75..10cc27158770 100644
--- a/fs/f2fs/checkpoint.c
+++ b/fs/f2fs/checkpoint.c
@@ -1419,7 +1419,9 @@ static void commit_checkpoint(struct f2fs_sb_info *sbi,
f2fs_folio_put(folio, false);
/* submit checkpoint (with barrier if NOBARRIER is not set) */
- f2fs_submit_merged_write(sbi, META_FLUSH);
+ f2fs_submit_merged_write(sbi,
+ sbi->flush_policy & BIT(FLUSH_POLICY_CP_NO_FUA) ?
+ META : META_FLUSH);
}
static inline u64 get_sectors_written(struct block_device *bdev)
@@ -1606,6 +1608,12 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA);
stat_cp_time(cpc, CP_TIME_WAIT_LAST_CP);
+ if (sbi->flush_policy & BIT(FLUSH_POLICY_CP_NO_FUA)) {
+ err = f2fs_flush_device_cache(sbi);
+ if (err)
+ return err;
+ }
+
/*
* invalidate intermediate page cache borrowed from meta inode which are
* used for migration of encrypted, verity or compressed inode's blocks.
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 5c0ea60e502e..5bba24ca15c8 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1621,6 +1621,11 @@ struct decompress_io_ctx {
#define MAX_COMPRESS_LOG_SIZE 8
#define MAX_COMPRESS_WINDOW_SIZE(log_size) ((PAGE_SIZE) << (log_size))
+enum flush_policy {
+ FLUSH_POLICY_CP_NO_FUA,
+ FLUSH_POLICY_MAX,
+};
+
struct f2fs_sb_info {
struct super_block *sb; /* pointer to VFS super block */
struct proc_dir_entry *s_proc; /* proc entry */
@@ -1873,6 +1878,8 @@ struct f2fs_sb_info {
/* carve out reserved_blocks from total blocks */
bool carve_out;
+ unsigned int flush_policy; /* flush policy */
+
#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/sysfs.c b/fs/f2fs/sysfs.c
index f736052dea50..b69015f1dc67 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -852,6 +852,13 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
return count;
}
+ if (!strcmp(a->attr.name, "flush_policy")) {
+ if (t >= BIT(FLUSH_POLICY_MAX))
+ return -EINVAL;
+ *ui = (unsigned int)t;
+ return count;
+ }
+
if (!strcmp(a->attr.name, "gc_boost_gc_multiple")) {
if (t < 1 || t > SEGS_PER_SEC(sbi))
return -EINVAL;
@@ -1175,6 +1182,7 @@ F2FS_SBI_GENERAL_RW_ATTR(blkzone_alloc_policy);
#endif
F2FS_SBI_GENERAL_RW_ATTR(carve_out);
F2FS_SBI_GENERAL_RW_ATTR(reserved_pin_section);
+F2FS_SBI_GENERAL_RW_ATTR(flush_policy);
/* STAT_INFO ATTR */
#ifdef CONFIG_F2FS_STAT_FS
@@ -1371,6 +1379,7 @@ static struct attribute *f2fs_attrs[] = {
ATTR_LIST(max_read_extent_count),
ATTR_LIST(carve_out),
ATTR_LIST(reserved_pin_section),
+ ATTR_LIST(flush_policy),
NULL,
};
ATTRIBUTE_GROUPS(f2fs);
--
2.49.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [f2fs-dev] [PATCH] f2fs: introduce flush_policy sysfs entry
2025-07-31 8:47 [PATCH] f2fs: introduce flush_policy sysfs entry Chao Yu
@ 2025-08-07 2:16 ` Zhiguo Niu
2025-08-07 2:47 ` Chao Yu
0 siblings, 1 reply; 3+ messages in thread
From: Zhiguo Niu @ 2025-08-07 2:16 UTC (permalink / raw)
To: Chao Yu; +Cc: jaegeuk, linux-kernel, linux-f2fs-devel
Chao Yu via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net>
于2025年7月31日周四 16:49写道：
>
> This patch introduces a new sysfs entry /sys/fs/f2fs/<disk>/flush_policy
> in order to tune performance of f2fs data flush flow.
>
> For example, checkpoint will use REQ_FUA to persist CP metadata, however,
> some kind device has bad performance on REQ_FUA command, result in that
> checkpoint being blocked for long time, w/ this sysfs entry, we can give
> an option to use REQ_PREFLUSH command instead of REQ_FUA during checkpoint,
> it can help to mitigate long latency of checkpoint.
>
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
> Documentation/ABI/testing/sysfs-fs-f2fs | 9 +++++++++
> fs/f2fs/checkpoint.c | 10 +++++++++-
> fs/f2fs/f2fs.h | 7 +++++++
> fs/f2fs/sysfs.c | 9 +++++++++
> 4 files changed, 34 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> index bc0e7fefc39d..2fedb44b713b 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -883,3 +883,12 @@ Date: June 2025
> Contact: "Daeho Jeong" <daehojeong@google.com>
> Description: Control GC algorithm for boost GC. 0: cost benefit, 1: greedy
> Default: 1
> +
> +What: /sys/fs/f2fs/<disk>/flush_policy
> +Date: July 2025
> +Contact: "Chao Yu" <chao@kernel.org>
> +Description: Device has different performance for the same flush methods, this node
> + can be used to tune performance by setting different flush methods.
> +
> + policy value description
> + 0x00000001 Use preflush instead of fua during checkpoint
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index bbe07e3a6c75..10cc27158770 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -1419,7 +1419,9 @@ static void commit_checkpoint(struct f2fs_sb_info *sbi,
> f2fs_folio_put(folio, false);
>
> /* submit checkpoint (with barrier if NOBARRIER is not set) */
> - f2fs_submit_merged_write(sbi, META_FLUSH);
> + f2fs_submit_merged_write(sbi,
> + sbi->flush_policy & BIT(FLUSH_POLICY_CP_NO_FUA) ?
> + META : META_FLUSH);
> }
>
> static inline u64 get_sectors_written(struct block_device *bdev)
> @@ -1606,6 +1608,12 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
> f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA);
> stat_cp_time(cpc, CP_TIME_WAIT_LAST_CP);
>
> + if (sbi->flush_policy & BIT(FLUSH_POLICY_CP_NO_FUA)) {
> + err = f2fs_flush_device_cache(sbi);
> + if (err)
> + return err;
> + }
Hi Chao,
sorry for late interruption.
f2fs_flush_device_cache is just used for multi device cases, so this patch will
not be suitable for a single device if the user changes flush_policy
by sysfs, otherwise it
will not use FUA write when committing checkpoint? Is this expected?
Thanks!
> +
> /*
> * invalidate intermediate page cache borrowed from meta inode which are
> * used for migration of encrypted, verity or compressed inode's blocks.
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 5c0ea60e502e..5bba24ca15c8 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1621,6 +1621,11 @@ struct decompress_io_ctx {
> #define MAX_COMPRESS_LOG_SIZE 8
> #define MAX_COMPRESS_WINDOW_SIZE(log_size) ((PAGE_SIZE) << (log_size))
>
> +enum flush_policy {
> + FLUSH_POLICY_CP_NO_FUA,
> + FLUSH_POLICY_MAX,
> +};
> +
> struct f2fs_sb_info {
> struct super_block *sb; /* pointer to VFS super block */
> struct proc_dir_entry *s_proc; /* proc entry */
> @@ -1873,6 +1878,8 @@ struct f2fs_sb_info {
> /* carve out reserved_blocks from total blocks */
> bool carve_out;
>
> + unsigned int flush_policy; /* flush policy */
> +
> #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/sysfs.c b/fs/f2fs/sysfs.c
> index f736052dea50..b69015f1dc67 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -852,6 +852,13 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
> return count;
> }
>
> + if (!strcmp(a->attr.name, "flush_policy")) {
> + if (t >= BIT(FLUSH_POLICY_MAX))
> + return -EINVAL;
> + *ui = (unsigned int)t;
> + return count;
> + }
> +
> if (!strcmp(a->attr.name, "gc_boost_gc_multiple")) {
> if (t < 1 || t > SEGS_PER_SEC(sbi))
> return -EINVAL;
> @@ -1175,6 +1182,7 @@ F2FS_SBI_GENERAL_RW_ATTR(blkzone_alloc_policy);
> #endif
> F2FS_SBI_GENERAL_RW_ATTR(carve_out);
> F2FS_SBI_GENERAL_RW_ATTR(reserved_pin_section);
> +F2FS_SBI_GENERAL_RW_ATTR(flush_policy);
>
> /* STAT_INFO ATTR */
> #ifdef CONFIG_F2FS_STAT_FS
> @@ -1371,6 +1379,7 @@ static struct attribute *f2fs_attrs[] = {
> ATTR_LIST(max_read_extent_count),
> ATTR_LIST(carve_out),
> ATTR_LIST(reserved_pin_section),
> + ATTR_LIST(flush_policy),
> NULL,
> };
> ATTRIBUTE_GROUPS(f2fs);
> --
> 2.49.0
>
>
>
> _______________________________________________
> Linux-f2fs-devel mailing list
> Linux-f2fs-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [f2fs-dev] [PATCH] f2fs: introduce flush_policy sysfs entry
2025-08-07 2:16 ` [f2fs-dev] " Zhiguo Niu
@ 2025-08-07 2:47 ` Chao Yu
0 siblings, 0 replies; 3+ messages in thread
From: Chao Yu @ 2025-08-07 2:47 UTC (permalink / raw)
To: Zhiguo Niu; +Cc: chao, jaegeuk, linux-kernel, linux-f2fs-devel
On 8/7/25 10:16, Zhiguo Niu wrote:
> Chao Yu via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net>
> 于2025年7月31日周四 16:49写道：
>>
>> This patch introduces a new sysfs entry /sys/fs/f2fs/<disk>/flush_policy
>> in order to tune performance of f2fs data flush flow.
>>
>> For example, checkpoint will use REQ_FUA to persist CP metadata, however,
>> some kind device has bad performance on REQ_FUA command, result in that
>> checkpoint being blocked for long time, w/ this sysfs entry, we can give
>> an option to use REQ_PREFLUSH command instead of REQ_FUA during checkpoint,
>> it can help to mitigate long latency of checkpoint.
>>
>> Signed-off-by: Chao Yu <chao@kernel.org>
>> ---
>> Documentation/ABI/testing/sysfs-fs-f2fs | 9 +++++++++
>> fs/f2fs/checkpoint.c | 10 +++++++++-
>> fs/f2fs/f2fs.h | 7 +++++++
>> fs/f2fs/sysfs.c | 9 +++++++++
>> 4 files changed, 34 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
>> index bc0e7fefc39d..2fedb44b713b 100644
>> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
>> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
>> @@ -883,3 +883,12 @@ Date: June 2025
>> Contact: "Daeho Jeong" <daehojeong@google.com>
>> Description: Control GC algorithm for boost GC. 0: cost benefit, 1: greedy
>> Default: 1
>> +
>> +What: /sys/fs/f2fs/<disk>/flush_policy
>> +Date: July 2025
>> +Contact: "Chao Yu" <chao@kernel.org>
>> +Description: Device has different performance for the same flush methods, this node
>> + can be used to tune performance by setting different flush methods.
>> +
>> + policy value description
>> + 0x00000001 Use preflush instead of fua during checkpoint
>> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
>> index bbe07e3a6c75..10cc27158770 100644
>> --- a/fs/f2fs/checkpoint.c
>> +++ b/fs/f2fs/checkpoint.c
>> @@ -1419,7 +1419,9 @@ static void commit_checkpoint(struct f2fs_sb_info *sbi,
>> f2fs_folio_put(folio, false);
>>
>> /* submit checkpoint (with barrier if NOBARRIER is not set) */
>> - f2fs_submit_merged_write(sbi, META_FLUSH);
>> + f2fs_submit_merged_write(sbi,
>> + sbi->flush_policy & BIT(FLUSH_POLICY_CP_NO_FUA) ?
>> + META : META_FLUSH);
>> }
>>
>> static inline u64 get_sectors_written(struct block_device *bdev)
>> @@ -1606,6 +1608,12 @@ static int do_checkpoint(struct f2fs_sb_info *sbi, struct cp_control *cpc)
>> f2fs_wait_on_all_pages(sbi, F2FS_WB_CP_DATA);
>> stat_cp_time(cpc, CP_TIME_WAIT_LAST_CP);
>>
>> + if (sbi->flush_policy & BIT(FLUSH_POLICY_CP_NO_FUA)) {
>> + err = f2fs_flush_device_cache(sbi);
>> + if (err)
>> + return err;
>> + }
> Hi Chao,
> sorry for late interruption.
> f2fs_flush_device_cache is just used for multi device cases, so this patch will
> not be suitable for a single device if the user changes flush_policy
> by sysfs, otherwise it
> will not use FUA write when committing checkpoint? Is this expected?
Zhiguo, I expected to flush primary device as well, so I need to fix this, thanks
for catching this.
Thanks,
> Thanks!
>> +
>> /*
>> * invalidate intermediate page cache borrowed from meta inode which are
>> * used for migration of encrypted, verity or compressed inode's blocks.
>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>> index 5c0ea60e502e..5bba24ca15c8 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -1621,6 +1621,11 @@ struct decompress_io_ctx {
>> #define MAX_COMPRESS_LOG_SIZE 8
>> #define MAX_COMPRESS_WINDOW_SIZE(log_size) ((PAGE_SIZE) << (log_size))
>>
>> +enum flush_policy {
>> + FLUSH_POLICY_CP_NO_FUA,
>> + FLUSH_POLICY_MAX,
>> +};
>> +
>> struct f2fs_sb_info {
>> struct super_block *sb; /* pointer to VFS super block */
>> struct proc_dir_entry *s_proc; /* proc entry */
>> @@ -1873,6 +1878,8 @@ struct f2fs_sb_info {
>> /* carve out reserved_blocks from total blocks */
>> bool carve_out;
>>
>> + unsigned int flush_policy; /* flush policy */
>> +
>> #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/sysfs.c b/fs/f2fs/sysfs.c
>> index f736052dea50..b69015f1dc67 100644
>> --- a/fs/f2fs/sysfs.c
>> +++ b/fs/f2fs/sysfs.c
>> @@ -852,6 +852,13 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
>> return count;
>> }
>>
>> + if (!strcmp(a->attr.name, "flush_policy")) {
>> + if (t >= BIT(FLUSH_POLICY_MAX))
>> + return -EINVAL;
>> + *ui = (unsigned int)t;
>> + return count;
>> + }
>> +
>> if (!strcmp(a->attr.name, "gc_boost_gc_multiple")) {
>> if (t < 1 || t > SEGS_PER_SEC(sbi))
>> return -EINVAL;
>> @@ -1175,6 +1182,7 @@ F2FS_SBI_GENERAL_RW_ATTR(blkzone_alloc_policy);
>> #endif
>> F2FS_SBI_GENERAL_RW_ATTR(carve_out);
>> F2FS_SBI_GENERAL_RW_ATTR(reserved_pin_section);
>> +F2FS_SBI_GENERAL_RW_ATTR(flush_policy);
>>
>> /* STAT_INFO ATTR */
>> #ifdef CONFIG_F2FS_STAT_FS
>> @@ -1371,6 +1379,7 @@ static struct attribute *f2fs_attrs[] = {
>> ATTR_LIST(max_read_extent_count),
>> ATTR_LIST(carve_out),
>> ATTR_LIST(reserved_pin_section),
>> + ATTR_LIST(flush_policy),
>> NULL,
>> };
>> ATTRIBUTE_GROUPS(f2fs);
>> --
>> 2.49.0
>>
>>
>>
>> _______________________________________________
>> Linux-f2fs-devel mailing list
>> Linux-f2fs-devel@lists.sourceforge.net
>> https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
^ permalink raw reply [flat|nested] 3+ messages in thread
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2025-07-31 8:47 [PATCH] f2fs: introduce flush_policy sysfs entry Chao Yu
2025-08-07 2:16 ` [f2fs-dev] " Zhiguo Niu
2025-08-07 2:47 ` Chao Yu
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