Re: [f2fs-dev] [PATCH v5] f2fs: support soft block reservation

[Chao Yu <chao@kernel.org>]

On 2017/10/27 19:47, Yunlong Song wrote:
> It supports to extend reserved_blocks sysfs interface to be soft
> threshold, which allows user configure it exceeding current available
> user space. This patch also introduces a new sysfs interface called
> current_reserved_blocks, which shows the current blocks that have
> already been reserved.
> 
> Signed-off-by: Yunlong Song <yunlong.song@huawei.com>
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> ---
>  Documentation/ABI/testing/sysfs-fs-f2fs | 15 +++++++++++++--
>  fs/f2fs/f2fs.h                          | 13 +++++++++++--
>  fs/f2fs/super.c                         |  3 ++-
>  fs/f2fs/sysfs.c                         | 15 ++++++++++++---
>  4 files changed, 38 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> index 11b7f4e..482d78b 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -134,11 +134,22 @@ Contact:	"Sheng Yong" <shengyong1@huawei.com>
>  Description:
>  		 Controls the injection type.
>  
> -What:		/sys/fs/f2fs/<disk>/reserved_blocks
> +What:		/sys/fs/f2fs/<disk>/target_reserved_blocks

It needs to keep old sysfs interface description as you did in code.

Thanks,

>  Date:		June 2017
>  Contact:	"Chao Yu" <yuchao0@huawei.com>
>  Description:
> -		 Controls current reserved blocks in system.
> +		 Controls target reserved blocks in system, the threshold
> +		 is soft, it could exceed current available user space.
> +
> +What:		/sys/fs/f2fs/<disk>/current_reserved_blocks
> +Date:		October 2017
> +Contact:	"Yunlong Song" <yunlong.song@huawei.com>
> +Contact:	"Chao Yu" <yuchao0@huawei.com>
> +Description:
> +		 Shows current reserved blocks in system, it may be temporarily
> +		 smaller than target_reserved_blocks, but will gradually
> +		 increase to target_reserved_blocks when more free blocks are
> +		 freed by user later.
>  
>  What:		/sys/fs/f2fs/<disk>/gc_urgent
>  Date:		August 2017
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 13a96b8..5ed40fb 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1082,6 +1082,7 @@ struct f2fs_sb_info {
>  	block_t discard_blks;			/* discard command candidats */
>  	block_t last_valid_block_count;		/* for recovery */
>  	block_t reserved_blocks;		/* configurable reserved blocks */
> +	block_t current_reserved_blocks;	/* current reserved blocks */
>  
>  	u32 s_next_generation;			/* for NFS support */
>  
> @@ -1557,7 +1558,8 @@ static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
>  
>  	spin_lock(&sbi->stat_lock);
>  	sbi->total_valid_block_count += (block_t)(*count);
> -	avail_user_block_count = sbi->user_block_count - sbi->reserved_blocks;
> +	avail_user_block_count = sbi->user_block_count -
> +					sbi->current_reserved_blocks;
>  	if (unlikely(sbi->total_valid_block_count > avail_user_block_count)) {
>  		diff = sbi->total_valid_block_count - avail_user_block_count;
>  		*count -= diff;
> @@ -1591,6 +1593,10 @@ static inline void dec_valid_block_count(struct f2fs_sb_info *sbi,
>  	f2fs_bug_on(sbi, sbi->total_valid_block_count < (block_t) count);
>  	f2fs_bug_on(sbi, inode->i_blocks < sectors);
>  	sbi->total_valid_block_count -= (block_t)count;
> +	if (sbi->reserved_blocks &&
> +		sbi->current_reserved_blocks < sbi->reserved_blocks)
> +		sbi->current_reserved_blocks = min(sbi->reserved_blocks,
> +					sbi->current_reserved_blocks + count);
>  	spin_unlock(&sbi->stat_lock);
>  	f2fs_i_blocks_write(inode, count, false, true);
>  }
> @@ -1737,7 +1743,7 @@ static inline int inc_valid_node_count(struct f2fs_sb_info *sbi,
>  	spin_lock(&sbi->stat_lock);
>  
>  	valid_block_count = sbi->total_valid_block_count + 1;
> -	if (unlikely(valid_block_count + sbi->reserved_blocks >
> +	if (unlikely(valid_block_count + sbi->current_reserved_blocks >
>  						sbi->user_block_count)) {
>  		spin_unlock(&sbi->stat_lock);
>  		goto enospc;
> @@ -1780,6 +1786,9 @@ static inline void dec_valid_node_count(struct f2fs_sb_info *sbi,
>  
>  	sbi->total_valid_node_count--;
>  	sbi->total_valid_block_count--;
> +	if (sbi->reserved_blocks &&
> +		sbi->current_reserved_blocks < sbi->reserved_blocks)
> +		sbi->current_reserved_blocks++;
>  
>  	spin_unlock(&sbi->stat_lock);
>  
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 213d2c1..dab1fed 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -987,7 +987,7 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
>  	buf->f_blocks = total_count - start_count;
>  	buf->f_bfree = user_block_count - valid_user_blocks(sbi) + ovp_count;
>  	buf->f_bavail = user_block_count - valid_user_blocks(sbi) -
> -						sbi->reserved_blocks;
> +						sbi->current_reserved_blocks;
>  
>  	avail_node_count = sbi->total_node_count - F2FS_RESERVED_NODE_NUM;
>  
> @@ -2458,6 +2458,7 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>  				le64_to_cpu(sbi->ckpt->valid_block_count);
>  	sbi->last_valid_block_count = sbi->total_valid_block_count;
>  	sbi->reserved_blocks = 0;
> +	sbi->current_reserved_blocks = 0;
>  
>  	for (i = 0; i < NR_INODE_TYPE; i++) {
>  		INIT_LIST_HEAD(&sbi->inode_list[i]);
> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
> index e09e59c..4166ac7 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -30,7 +30,7 @@ enum {
>  	FAULT_INFO_RATE,	/* struct f2fs_fault_info */
>  	FAULT_INFO_TYPE,	/* struct f2fs_fault_info */
>  #endif
> -	RESERVED_BLOCKS,
> +	RESERVED_BLOCKS,	/* struct f2fs_sb_info */
>  };
>  
>  struct f2fs_attr {
> @@ -114,6 +114,12 @@ static ssize_t features_show(struct f2fs_attr *a,
>  	return len;
>  }
>  
> +static ssize_t current_reserved_blocks_show(struct f2fs_attr *a,
> +					struct f2fs_sb_info *sbi, char *buf)
> +{
> +	return snprintf(buf, PAGE_SIZE, "%u\n", sbi->current_reserved_blocks);
> +}
> +
>  static ssize_t f2fs_sbi_show(struct f2fs_attr *a,
>  			struct f2fs_sb_info *sbi, char *buf)
>  {
> @@ -153,12 +159,13 @@ static ssize_t f2fs_sbi_store(struct f2fs_attr *a,
>  #endif
>  	if (a->struct_type == RESERVED_BLOCKS) {
>  		spin_lock(&sbi->stat_lock);
> -		if ((unsigned long)sbi->total_valid_block_count + t >
> -				(unsigned long)sbi->user_block_count) {
> +		if (t > (unsigned long)sbi->user_block_count) {
>  			spin_unlock(&sbi->stat_lock);
>  			return -EINVAL;
>  		}
>  		*ui = t;
> +		sbi->current_reserved_blocks = min(sbi->reserved_blocks,
> +				sbi->user_block_count - valid_user_blocks(sbi));
>  		spin_unlock(&sbi->stat_lock);
>  		return count;
>  	}
> @@ -293,6 +300,7 @@ static ssize_t f2fs_feature_show(struct f2fs_attr *a,
>  F2FS_GENERAL_RO_ATTR(dirty_segments);
>  F2FS_GENERAL_RO_ATTR(lifetime_write_kbytes);
>  F2FS_GENERAL_RO_ATTR(features);
> +F2FS_GENERAL_RO_ATTR(current_reserved_blocks);
>  
>  #ifdef CONFIG_F2FS_FS_ENCRYPTION
>  F2FS_FEATURE_RO_ATTR(encryption, FEAT_CRYPTO);
> @@ -338,6 +346,7 @@ static ssize_t f2fs_feature_show(struct f2fs_attr *a,
>  	ATTR_LIST(lifetime_write_kbytes),
>  	ATTR_LIST(features),
>  	ATTR_LIST(reserved_blocks),
> +	ATTR_LIST(current_reserved_blocks),
>  	NULL,
>  };
>  
>