Re: [PATCH v3 1/3] f2fs: fix to set ipu policy

[Chao Yu]

On 2023/2/2 16:48, Yangtao Li wrote:
> For LFS mode, it should update outplace and no need inplace update.
> When using LFS mode for small-volume devices, IPU will not be used,
> and the OPU writing method is actually used, but F2FS_IPU_FORCE can
> be read from the ipu_policy node, which is different from the actual
> situation. And remount to lfs mode should be disallowed when
> f2fs ipu is enabled, let's fix it.
>
> Fixes: 84b89e5d943d ("f2fs: add auto tuning for small devices")
> Signed-off-by: Yangtao Li <frank.li@xxxxxxxx>
> ---
> v3:
> -add check in __sbi_store()
> -introduce IS_F2FS_IPU_DISABLE()
> -convert to f2fs_lfs_mode()
>   fs/f2fs/segment.h | 10 +++++++++-
>   fs/f2fs/super.c   | 13 +++++++++----
>   fs/f2fs/sysfs.c   |  9 +++++++++
>   3 files changed, 27 insertions(+), 5 deletions(-)
>
> diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
> index 0f3f05cb8c29..8ee5e5db9287 100644
> --- a/fs/f2fs/segment.h
> +++ b/fs/f2fs/segment.h
> @@ -670,6 +670,8 @@ static inline int utilization(struct f2fs_sb_info *sbi)
>   
>   #define SMALL_VOLUME_SEGMENTS	(16 * 512)	/* 16GB */
>   
> +#define F2FS_IPU_DISABLE	0
> +
>   enum {
>   	F2FS_IPU_FORCE,
>   	F2FS_IPU_SSR,
> @@ -679,10 +681,16 @@ enum {
>   	F2FS_IPU_ASYNC,
>   	F2FS_IPU_NOCACHE,
>   	F2FS_IPU_HONOR_OPU_WRITE,
> +	F2FS_IPU_MAX,
>   };
>   
> +static inline bool IS_F2FS_IPU_DISABLE(struct f2fs_sb_info *sbi)
> +{
> +	return SM_I(sbi)->ipu_policy == F2FS_IPU_DISABLE;
> +}
> +
>   #define F2FS_IPU_POLICY(name)					\
> -static inline int IS_##name(struct f2fs_sb_info *sbi)		\
> +static inline bool IS_##name(struct f2fs_sb_info *sbi)		\
>   {								\
>   	return SM_I(sbi)->ipu_policy & BIT(name);		\
>   }
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index fddff5deaed2..f06af2af215f 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -2302,6 +2302,12 @@ static int f2fs_remount(struct super_block *sb, int *flags, char *data)
>   		}
>   	}
>   #endif
> +	if (f2fs_lfs_mode(sbi) && !IS_F2FS_IPU_DISABLE(sbi)) {
> +		err = -EINVAL;
> +		f2fs_warn(sbi, "LFS not compatible with IPU");

LFS is not compatible with IPU

> +		goto restore_opts;
> +	}
> +
>   	/* disallow enable atgc dynamically */
>   	if (no_atgc == !!test_opt(sbi, ATGC)) {
>   		err = -EINVAL;
> @@ -4081,10 +4087,9 @@ static void f2fs_tuning_parameters(struct f2fs_sb_info *sbi)
>   	/* adjust parameters according to the volume size */
>   	if (MAIN_SEGS(sbi) <= SMALL_VOLUME_SEGMENTS) {
>   		if (f2fs_block_unit_discard(sbi))
> -			SM_I(sbi)->dcc_info->discard_granularity =
> -						MIN_DISCARD_GRANULARITY;
> -		SM_I(sbi)->ipu_policy = BIT(F2FS_IPU_FORCE) |
> -					BIT(F2FS_IPU_HONOR_OPU_WRITE);
> +			SM_I(sbi)->dcc_info->discard_granularity = MIN_DISCARD_GRANULARITY;
> +		if (!f2fs_lfs_mode(sbi))
> +			SM_I(sbi)->ipu_policy = BIT(F2FS_IPU_FORCE) | BIT(F2FS_IPU_HONOR_OPU_WRITE);
>   	}
>   
>   	sbi->readdir_ra = true;
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index 3c6425f9ed0a..e1f1ebfa59d6 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -697,6 +697,15 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
>   		return count;
>   	}
>   
> +	if (!strcmp(a->attr.name, "ipu_policy")) {
> +		if (f2fs_lfs_mode(sbi))
> +			return -EINVAL;
> +		if (t >= BIT(F2FS_IPU_MAX))
> +			return -EINVAL;

if (t && f2fs_lfs_mode(sbi))
	return -EINVAL;

> +		SM_I(sbi)->ipu_policy = (unsigned int)t;
> +		return count;
> +	}
> +
>   	*ui = (unsigned int)t;
>   
>   	return count;