Re: [PATCH v3] f2fs: add cur_reserved_blocks to support soft block reservation

[Yunlong Song <yunlong.song@huawei.com>]

ping...

On 2017/8/18 23:09, Yunlong Song wrote:
> This patch adds cur_reserved_blocks to extend reserved_blocks sysfs
> interface to be soft threshold, which allows user configure it exceeding
> current available user space. To ensure there is enough space for
> supporting system's activation, this patch does not set the reserved space
> to the configured reserved_blocks value at once, instead, it safely
> increase cur_reserved_blocks in dev_valid_block(,node)_count to only take
> up the blocks which are just obsoleted.
>
> Signed-off-by: Yunlong Song <yunlong.song@huawei.com>
> Signed-off-by: Chao Yu <yuchao0@huawei.com>
> ---
>   Documentation/ABI/testing/sysfs-fs-f2fs |  3 ++-
>   fs/f2fs/f2fs.h                          | 13 +++++++++++--
>   fs/f2fs/super.c                         |  3 ++-
>   fs/f2fs/sysfs.c                         | 15 +++++++++++++--
>   4 files changed, 28 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
> index 11b7f4e..ba282ca 100644
> --- a/Documentation/ABI/testing/sysfs-fs-f2fs
> +++ b/Documentation/ABI/testing/sysfs-fs-f2fs
> @@ -138,7 +138,8 @@ What:		/sys/fs/f2fs/<disk>/reserved_blocks
>   Date:		June 2017
>   Contact:	"Chao Yu" <yuchao0@huawei.com>
>   Description:
> -		 Controls current reserved blocks in system.
> +		 Controls current reserved blocks in system, the threshold
> +		 is soft, it could exceed current available user space.
>   
>   What:		/sys/fs/f2fs/<disk>/gc_urgent
>   Date:		August 2017
> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> index 2f20b6b..84ccbdc 100644
> --- a/fs/f2fs/f2fs.h
> +++ b/fs/f2fs/f2fs.h
> @@ -1041,6 +1041,7 @@ 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 cur_reserved_blocks;		/* current reserved blocks */
>   
>   	u32 s_next_generation;			/* for NFS support */
>   
> @@ -1515,7 +1516,8 @@ 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->cur_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;
> @@ -1549,6 +1551,10 @@ 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->reserved_blocks != sbi->cur_reserved_blocks)
> +		sbi->cur_reserved_blocks = min(sbi->reserved_blocks,
> +					sbi->cur_reserved_blocks + count);
>   	spin_unlock(&sbi->stat_lock);
>   	f2fs_i_blocks_write(inode, count, false, true);
>   }
> @@ -1695,7 +1701,7 @@ 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->cur_reserved_blocks >
>   						sbi->user_block_count)) {
>   		spin_unlock(&sbi->stat_lock);
>   		goto enospc;
> @@ -1738,6 +1744,9 @@ 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->reserved_blocks != sbi->cur_reserved_blocks)
> +		sbi->cur_reserved_blocks++;
>   
>   	spin_unlock(&sbi->stat_lock);
>   
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 4c1bdcb..16a805f 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -957,7 +957,7 @@ 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->cur_reserved_blocks;
>   
>   	avail_node_count = sbi->total_node_count - F2FS_RESERVED_NODE_NUM;
>   
> @@ -2411,6 +2411,7 @@ 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->cur_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 a1be5ac..75c37bb 100644
> --- a/fs/f2fs/sysfs.c
> +++ b/fs/f2fs/sysfs.c
> @@ -104,12 +104,22 @@ static ssize_t features_show(struct f2fs_attr *a,
>   	return len;
>   }
>   
> +static ssize_t f2fs_reserved_blocks_show(struct f2fs_attr *a,
> +		struct f2fs_sb_info *sbi, char *buf)
> +{
> +	return snprintf(buf, PAGE_SIZE, "expected: %u\ncurrent: %u\n",
> +			sbi->reserved_blocks, sbi->cur_reserved_blocks);
> +}
> +
>   static ssize_t f2fs_sbi_show(struct f2fs_attr *a,
>   			struct f2fs_sb_info *sbi, char *buf)
>   {
>   	unsigned char *ptr = NULL;
>   	unsigned int *ui;
>   
> +	if (a->struct_type == RESERVED_BLOCKS)
> +		return f2fs_reserved_blocks_show(a, sbi, buf);
> +
>   	ptr = __struct_ptr(sbi, a->struct_type);
>   	if (!ptr)
>   		return -EINVAL;
> @@ -143,12 +153,13 @@ 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;
> +		if (t < (unsigned long)sbi->cur_reserved_blocks)
> +			sbi->cur_reserved_blocks = t;
>   		spin_unlock(&sbi->stat_lock);
>   		return count;
>   	}

-- 
Thanks,
Yunlong Song



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