linux-kernel - Re: [PATCH] f2fs: restrict write IO alignment condition

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Message-ID: <20170310185005.GC22979@jaegeuk.local>
Date:   Fri, 10 Mar 2017 10:50:05 -0800
From:   Jaegeuk Kim <jaegeuk@...nel.org>
To:     Chao Yu <yuchao0@...wei.com>
Cc:     linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, chao@...nel.org
Subject: Re: [PATCH] f2fs: restrict write IO alignment condition

On 03/10, Chao Yu wrote:
> We should only align start offset of bio with defined IO_SIZE for below
> conditions:
> a. write IOs
> b. Out-place-update
> c. non-meta page
> 
> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> ---
>  fs/f2fs/data.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 1375fef11146..3e6b0cc5e36a 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -395,7 +395,9 @@ int f2fs_submit_page_mbio(struct f2fs_io_info *fio)
>  		__submit_merged_bio(io);
>  alloc_new:
>  	if (io->bio == NULL) {
> -		if ((fio->type == DATA || fio->type == NODE) &&
> +		if (!is_read && (fio->type == DATA || fio->type == NODE) &&
> +				bio_page->mapping != META_MAPPING(sbi) &&

BUG_ON(), since it's covered by fio->type == DATA || fio->type == NODE.

> +				fio->new_blkaddr != fio->old_blkaddr &&

BUG_ON(), since LFS mount option doesn't allow any in-place updates.

>  				fio->new_blkaddr & F2FS_IO_SIZE_MASK(sbi)) {

So, is_read is worth to check?

Thanks,

>  			err = -EAGAIN;
>  			if (!is_read)
> -- 
> 2.8.2.295.g3f1c1d0