linux-kernel - Re: [PATCH] f2fs: fix to align to section for fallocate() on pinned file

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Date:   Tue, 23 Mar 2021 11:32:47 -0700
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <chao@...nel.org>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, Chao Yu <yuchao0@...wei.com>
Subject: Re: [PATCH] f2fs: fix to align to section for fallocate() on pinned
 file

On 03/23, Chao Yu wrote:
> On 2021/3/5 17:56, Chao Yu wrote:
> > Now, fallocate() on a pinned file only allocates blocks which aligns
> > to segment rather than section, so GC may try to migrate pinned file's
> > block, and after several times of failure, pinned file's block could
> > be migrated to other place, however user won't be aware of such
> > condition, and then old obsolete block address may be readed/written
> > incorrectly.
> > 
> > To avoid such condition, let's try to allocate pinned file's blocks
> > with section alignment.
> > 
> > Signed-off-by: Chao Yu <yuchao0@...wei.com>
> 
> Jaegeuk,
> 
> Could you please check and apply below diff into original patch?
> 
> ---
>  fs/f2fs/file.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 236f3f69681a..24fa68fdcaa0 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -1648,13 +1648,13 @@ static int expand_inode_data(struct inode *inode, loff_t offset,
>  		return 0;
> 
>  	if (f2fs_is_pinned_file(inode)) {
> -		block_t len = (map.m_len >> sbi->log_blocks_per_seg) <<
> -					sbi->log_blocks_per_seg;
> +		block_t sec_blks = BLKS_PER_SEC(sbi);
> +		block_t len = rounddown(map.m_len, sec_blks);

len is declared above, so let me rephrase this as well.

> 
> -		if (map.m_len % sbi->blocks_per_seg)
> -			len += sbi->blocks_per_seg;
> +		if (map.m_len % sec_blks)
> +			len += sec_blks;

is this roundup()?

Could you check this?
https://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs.git/commit/?h=dev&id=e1175f02291141bbd924fc578299305fcde35855

> 
> -		map.m_len = sbi->blocks_per_seg;
> +		map.m_len = sec_blks;
>  next_alloc:
>  		if (has_not_enough_free_secs(sbi, 0,
>  			GET_SEC_FROM_SEG(sbi, overprovision_segments(sbi)))) {
> -- 
> 2.22.1
>