linux-kernel - Re: [f2fs-dev] [PATCH 2/2] f2fs: report # of free inodes more precisely

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Message-ID: <20170701072700.GA83795@jaegeuk-macbookpro.roam.corp.google.com>
Date:   Sat, 1 Jul 2017 00:27:00 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <chao@...nel.org>
Cc:     Chao Yu <yuchao0@...wei.com>, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 2/2] f2fs: report # of free inodes more
 precisely

On 06/28, Chao Yu wrote:
> On 2017/6/26 22:58, Jaegeuk Kim wrote:
> > On 06/26, Chao Yu wrote:
> >> Hi Jaegeuk,
> >>
> >> On 2017/6/25 0:25, Jaegeuk Kim wrote:
> >>> If the partition is small, we don't need to report total # of inodes including
> >>> hidden free nodes.
> >>>
> >>> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> >>> ---
> >>>  fs/f2fs/super.c | 14 +++++++++++---
> >>>  1 file changed, 11 insertions(+), 3 deletions(-)
> >>>
> >>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> >>> index 8e39b850bfc0..3da6fb276f8b 100644
> >>> --- a/fs/f2fs/super.c
> >>> +++ b/fs/f2fs/super.c
> >>> @@ -680,6 +680,7 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
> >>>  	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;
> >>> +	u64 avail_node_count;
> >>>  
> >>>  	total_count = le64_to_cpu(sbi->raw_super->block_count);
> >>>  	user_block_count = sbi->user_block_count;
> >>> @@ -692,9 +693,16 @@ static int f2fs_statfs(struct dentry *dentry, struct kstatfs *buf)
> >>>  	buf->f_bfree = user_block_count - valid_user_blocks(sbi) + ovp_count;
> >>>  	buf->f_bavail = user_block_count - valid_user_blocks(sbi);
> >>>  
> >>> -	buf->f_files = sbi->total_node_count - F2FS_RESERVED_NODE_NUM;
> >>> -	buf->f_ffree = min(buf->f_files - valid_node_count(sbi),
> >>> -							buf->f_bavail);
> >>> +	avail_node_count = sbi->total_node_count - F2FS_RESERVED_NODE_NUM;
> >>> +
> >>> +	if (avail_node_count > user_block_count) {
> >>> +		buf->f_files = user_block_count;
> >>> +		buf->f_ffree = buf->f_bavail;
> >>
> >> f_ffree is limited both by remained free nid count and free block count, so it
> >> needs to change like this?
> > 
> > I thought both of them are same, since node block will consume user block. So,
> > we don't need to do min() again.
> 
> avail_node_count comes from total free nid counts which is limited with
> nid_bitmap size, buf->f_bavail comes from total user block count which
> can both cosumed by node and data. So the value of them may not be the same.

What I mean was, if avail_node_count is larger than user_block_count, we can
see buf->f_bavail is always smaller than avali_node_count - valid_node_count,
since node blocks concumes blocks as well.

> 
> Thanks,
> 
> > 
> >>
> >> if (avail_node_count > user_block_count)
> >> 	avail_node_count = user_block_count;
> >>
> >> buf->f_files = avail_node_count;
> >> buf->f_ffree = min(avail_node_count - valid_node_count(sbi),
> >> 					buf->f_bavail);
> >>
> >> Thanks,
> >>
> >>> +	} else {
> >>> +		buf->f_files = avail_node_count;
> >>> +		buf->f_ffree = min(avail_node_count - valid_node_count(sbi),
> >>> +					buf->f_bavail);
> >>> +	}
> >>>  
> >>>  	buf->f_namelen = F2FS_NAME_LEN;
> >>>  	buf->f_fsid.val[0] = (u32)id;
> >>>
> > 
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