Date:   Thu, 4 Jan 2018 09:16:18 +0800
From:   Chao Yu <yuchao0@...wei.com>
To:     Jaegeuk Kim <jaegeuk@...nel.org>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-f2fs-devel@...ts.sourceforge.net>
Subject: Re: [f2fs-dev] [PATCH v5] f2fs: add reserved blocks for root user

On 2018/1/4 3:06, Jaegeuk Kim wrote:
> On 01/03, Chao Yu wrote:
>> On 2018/1/3 10:21, Jaegeuk Kim wrote:
>>> This patch allows root to reserve some blocks via mount option.
>>>
>>> "-o reserve_root=N" means N x 4KB-sized blocks for root only.
>>>
>>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
>>> ---
>>>
>>> Change log from v4:
>>>  - fix f_bfree in statfs
>>
>> Could you fix f_bfree calculation issue in another patch prior to this
>> patch? That will be better for history tracking of patches or git bisect
>> when backtracking issues.
> 
> I've sent out a new series for this.
> 
>>
>> One more thing, should we move reserve_root_limit check to parse_option?
> 
> No, since we don't have sbi yet.
> 
>> now, it looks that during remount we can set root_reserved_blocks exceeding
>> our defined limitation.
> 
> Oh, I missed the changelog that it won't be changed once getting the flag set.

If the flag is not set previously, and then we remount with that flag being
set?

Like:

mount -t f2fs /dev/xxx /mnt/
mount -t f2fs -o remount,reserve_root=xxx /dev/xxx /mnt/

Thanks,

> 
> Thanks,
> 
>>
>> Thanks,
>>
>>>
>>>  fs/f2fs/f2fs.h  | 26 ++++++++++++++++++++++----
>>>  fs/f2fs/super.c | 34 +++++++++++++++++++++++++++++-----
>>>  fs/f2fs/sysfs.c |  3 ++-
>>>  3 files changed, 53 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
>>> index 07e03990420b..a0e8eec23125 100644
>>> --- a/fs/f2fs/f2fs.h
>>> +++ b/fs/f2fs/f2fs.h
>>> @@ -95,6 +95,7 @@ extern char *fault_name[FAULT_MAX];
>>>  #define F2FS_MOUNT_PRJQUOTA		0x00200000
>>>  #define F2FS_MOUNT_QUOTA		0x00400000
>>>  #define F2FS_MOUNT_INLINE_XATTR_SIZE	0x00800000
>>> +#define F2FS_MOUNT_RESERVE_ROOT		0x01000000
>>>  
>>>  #define clear_opt(sbi, option)	((sbi)->mount_opt.opt &= ~F2FS_MOUNT_##option)
>>>  #define set_opt(sbi, option)	((sbi)->mount_opt.opt |= F2FS_MOUNT_##option)
>>> @@ -1105,6 +1106,7 @@ struct f2fs_sb_info {
>>>  	block_t last_valid_block_count;		/* for recovery */
>>>  	block_t reserved_blocks;		/* configurable reserved blocks */
>>>  	block_t current_reserved_blocks;	/* current reserved blocks */
>>> +	block_t root_reserved_blocks;		/* root reserved blocks */
>>>  
>>>  	unsigned int nquota_files;		/* # of quota sysfile */
>>>  
>>> @@ -1554,6 +1556,12 @@ static inline bool f2fs_has_xattr_block(unsigned int ofs)
>>>  	return ofs == XATTR_NODE_OFFSET;
>>>  }
>>>  
>>> +static inline block_t reserve_root_limit(struct f2fs_sb_info *sbi)
>>> +{
>>> +	/* limit is 0.2% */
>>> +	return (sbi->user_block_count << 1) / 1000;
>>> +}
>>> +
>>>  static inline void f2fs_i_blocks_write(struct inode *, block_t, bool, bool);
>>>  static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
>>>  				 struct inode *inode, blkcnt_t *count)
>>> @@ -1583,11 +1591,17 @@ static inline int inc_valid_block_count(struct f2fs_sb_info *sbi,
>>>  	sbi->total_valid_block_count += (block_t)(*count);
>>>  	avail_user_block_count = sbi->user_block_count -
>>>  					sbi->current_reserved_blocks;
>>> +
>>> +	if (!(test_opt(sbi, RESERVE_ROOT) && capable(CAP_SYS_RESOURCE)))
>>> +		avail_user_block_count -= sbi->root_reserved_blocks;
>>> +
>>>  	if (unlikely(sbi->total_valid_block_count > avail_user_block_count)) {
>>>  		diff = sbi->total_valid_block_count - avail_user_block_count;
>>> +		if (diff > *count)
>>> +			diff = *count;
>>>  		*count -= diff;
>>>  		release = diff;
>>> -		sbi->total_valid_block_count = avail_user_block_count;
>>> +		sbi->total_valid_block_count -= diff;
>>>  		if (!*count) {
>>>  			spin_unlock(&sbi->stat_lock);
>>>  			percpu_counter_sub(&sbi->alloc_valid_block_count, diff);
>>> @@ -1776,9 +1790,13 @@ 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->current_reserved_blocks >
>>> -						sbi->user_block_count)) {
>>> +	valid_block_count = sbi->total_valid_block_count +
>>> +					sbi->current_reserved_blocks + 1;
>>> +
>>> +	if (!(test_opt(sbi, RESERVE_ROOT) && capable(CAP_SYS_RESOURCE)))
>>> +		valid_block_count += sbi->root_reserved_blocks;
>>> +
>>> +	if (unlikely(valid_block_count > sbi->user_block_count)) {
>>>  		spin_unlock(&sbi->stat_lock);
>>>  		goto enospc;
>>>  	}
>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>>> index 5c6a02b558f0..e814340bc2f0 100644
>>> --- a/fs/f2fs/super.c
>>> +++ b/fs/f2fs/super.c
>>> @@ -107,6 +107,7 @@ enum {
>>>  	Opt_noextent_cache,
>>>  	Opt_noinline_data,
>>>  	Opt_data_flush,
>>> +	Opt_reserve_root,
>>>  	Opt_mode,
>>>  	Opt_io_size_bits,
>>>  	Opt_fault_injection,
>>> @@ -157,6 +158,7 @@ static match_table_t f2fs_tokens = {
>>>  	{Opt_noextent_cache, "noextent_cache"},
>>>  	{Opt_noinline_data, "noinline_data"},
>>>  	{Opt_data_flush, "data_flush"},
>>> +	{Opt_reserve_root, "reserve_root=%u"},
>>>  	{Opt_mode, "mode=%s"},
>>>  	{Opt_io_size_bits, "io_bits=%u"},
>>>  	{Opt_fault_injection, "fault_injection=%u"},
>>> @@ -488,6 +490,18 @@ static int parse_options(struct super_block *sb, char *options)
>>>  		case Opt_data_flush:
>>>  			set_opt(sbi, DATA_FLUSH);
>>>  			break;
>>> +		case Opt_reserve_root:
>>> +			if (args->from && match_int(args, &arg))
>>> +				return -EINVAL;
>>> +			if (test_opt(sbi, RESERVE_ROOT)) {
>>> +				f2fs_msg(sb, KERN_INFO,
>>> +					"Preserve previous reserve_root=%u",
>>> +					sbi->root_reserved_blocks);
>>> +			} else {
>>> +				sbi->root_reserved_blocks = arg;
>>> +				set_opt(sbi, RESERVE_ROOT);
>>> +			}
>>> +			break;
>>>  		case Opt_mode:
>>>  			name = match_strdup(&args[0]);
>>>  
>>> @@ -994,21 +1008,21 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
>>>  	struct super_block *sb = dentry->d_sb;
>>>  	struct f2fs_sb_info *sbi = F2FS_SB(sb);
>>>  	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
>>> -	block_t total_count, user_block_count, start_count, ovp_count;
>>> +	block_t total_count, user_block_count, start_count;
>>>  	u64 avail_node_count;
>>>  
>>>  	total_count = le64_to_cpu(sbi->raw_super->block_count);
>>>  	user_block_count = sbi->user_block_count;
>>>  	start_count = le32_to_cpu(sbi->raw_super->segment0_blkaddr);
>>> -	ovp_count = SM_I(sbi)->ovp_segments << sbi->log_blocks_per_seg;
>>>  	buf->f_type = F2FS_SUPER_MAGIC;
>>>  	buf->f_bsize = sbi->blocksize;
>>>  
>>>  	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) -
>>> +	buf->f_bfree = user_block_count - valid_user_blocks(sbi) -
>>>  						sbi->current_reserved_blocks;
>>> -
>>> +	buf->f_bavail = user_block_count - valid_user_blocks(sbi) -
>>> +						sbi->current_reserved_blocks -
>>> +						sbi->root_reserved_blocks;
>>>  	avail_node_count = sbi->total_node_count - sbi->nquota_files -
>>>  						F2FS_RESERVED_NODE_NUM;
>>>  
>>> @@ -1136,6 +1150,9 @@ static int f2fs_show_options(struct seq_file *seq, struct dentry *root)
>>>  	else if (test_opt(sbi, LFS))
>>>  		seq_puts(seq, "lfs");
>>>  	seq_printf(seq, ",active_logs=%u", sbi->active_logs);
>>> +	if (test_opt(sbi, RESERVE_ROOT))
>>> +		seq_printf(seq, ",reserve_root=%u",
>>> +				sbi->root_reserved_blocks);
>>>  	if (F2FS_IO_SIZE_BITS(sbi))
>>>  		seq_printf(seq, ",io_size=%uKB", F2FS_IO_SIZE_KB(sbi));
>>>  #ifdef CONFIG_F2FS_FAULT_INJECTION
>>> @@ -2571,6 +2588,13 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
>>>  	sbi->reserved_blocks = 0;
>>>  	sbi->current_reserved_blocks = 0;
>>>  
>>> +	if (test_opt(sbi, RESERVE_ROOT) &&
>>> +		sbi->root_reserved_blocks > reserve_root_limit(sbi)) {
>>> +		sbi->root_reserved_blocks = reserve_root_limit(sbi);
>>> +		f2fs_msg(sb, KERN_INFO,
>>> +			"Reduce reserved blocks for root = %u\n",
>>> +				sbi->root_reserved_blocks);
>>> +	}
>>>  	for (i = 0; i < NR_INODE_TYPE; i++) {
>>>  		INIT_LIST_HEAD(&sbi->inode_list[i]);
>>>  		spin_lock_init(&sbi->inode_lock[i]);
>>> diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
>>> index 93c3364250dd..ab6028c332aa 100644
>>> --- a/fs/f2fs/sysfs.c
>>> +++ b/fs/f2fs/sysfs.c
>>> @@ -162,7 +162,8 @@ static ssize_t f2fs_sbi_store(struct f2fs_attr *a,
>>>  #endif
>>>  	if (a->struct_type == RESERVED_BLOCKS) {
>>>  		spin_lock(&sbi->stat_lock);
>>> -		if (t > (unsigned long)sbi->user_block_count) {
>>> +		if (t > (unsigned long)(sbi->user_block_count -
>>> +					sbi->root_reserved_blocks)) {
>>>  			spin_unlock(&sbi->stat_lock);
>>>  			return -EINVAL;
>>>  		}
>>>
> 
> .
> 

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