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SubjectRe: [PATCH v2] f2fs: introduce cur_reserved_blocks in sysfs
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Hi, Chao,

ping...

Please see the review comment below. And the change is already in the v3
patch.

On 2017/8/18 23:16, Yunlong Song wrote:
> I send a v3 patch, please review, and the main difference is shown below.
>
> On 2017/8/18 18:20, Chao Yu wrote:
>> Hi Yunlong,
>>
>> IMO, we don't need additional sysfs entry, how about changing a bit
>> as below?
>>
>> >From 3fc8206871fe457859f1537c9dc8918b45f14601 Mon Sep 17 00:00:00 2001
>> From: Yunlong Song <yunlong.song@huawei.com>
>> Date: Wed, 16 Aug 2017 23:01:56 +0800
>> Subject: [PATCH] f2fs: support soft block reservation
>>
>> It supports to extend reserved_blocks sysfs interface to be soft
>> threshold, which allows user configure it exceeding current available
>> user space.
>>
>> 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 | 12 ++++++++++--
>> fs/f2fs/super.c | 3 ++-
>> fs/f2fs/sysfs.c | 16 ++++++++++++++--
>> 4 files changed, 28 insertions(+), 6 deletions(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs
>> b/Documentation/ABI/testing/sysfs-fs-f2fs
>> index 11b7f4ebea7c..45c3d92f77c8 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 avaible 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 336021b9b93e..a7b2d257e8ee 100644
>> --- a/fs/f2fs/f2fs.h
>> +++ b/fs/f2fs/f2fs.h
>> @@ -1046,6 +1046,7 @@ 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 */
>>
>> @@ -1520,7 +1521,8 @@ 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;
>> @@ -1554,6 +1556,9 @@ 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)
> Add sbi->reserved_blocks != sbi->cur_reserved_blocks check
>> + 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);
>> }
>> @@ -1700,7 +1705,7 @@ 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;
>> @@ -1743,6 +1748,9 @@ 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 = min(sbi->reserved_blocks,
>> + sbi->current_reserved_blocks + 1);
> change to sbi->cur_reserved_blocks++;
>>
>> spin_unlock(&sbi->stat_lock);
>>
>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>> index 4c1bdcb94133..036f083bbf56 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->current_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->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 4bcaa9059026..3173a272fe7c 100644
>> --- a/fs/f2fs/sysfs.c
>> +++ b/fs/f2fs/sysfs.c
>> @@ -104,12 +104,23 @@ 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->current_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 +154,13 @@ 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));
> This is not safe for support system's activation, since the user
> available space can be suddenly zero!
> So I change this to only admit t < sbi->cur_reserved_blocks then
> change its value.
>> spin_unlock(&sbi->stat_lock);
>> return count;
>> }
>

--
Thanks,
Yunlong Song


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