linux-kernel - Re: [PATCH] f2fs: add a wait step when submit bio with {READ,WRITE}

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Date:	Tue, 30 Jul 2013 21:29:58 +0900
From:	Jaegeuk Kim <jaegeuk.kim@...sung.com>
To:	Gu Zheng <guz.fnst@...fujitsu.com>
Cc:	f2fs <linux-f2fs-devel@...ts.sourceforge.net>,
	fsdevel <linux-fsdevel@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] f2fs: add a wait step when submit bio with
 {READ,WRITE}_SYNC

Hi Gu,

The original read flow was to avoid redandunt lock/unlock_page() calls.
And we should not wait for WRITE_SYNC, since it is just for write
priority, not for synchronization of the file system.
Thanks,

2013-07-30 (화), 18:06 +0800, Gu Zheng:
> When we submit bio with READ_SYNC or WRITE_SYNC, we need to wait a
> moment for the io completion, current codes only find_data_page() follows the
> rule, other places missing this step, so add it.
> 
> Further more, moving the PageUptodate check into f2fs_readpage() to clean up
> the codes.
> 
> Signed-off-by: Gu Zheng <guz.fnst@...fujitsu.com>
> ---
>  fs/f2fs/checkpoint.c |    1 -
>  fs/f2fs/data.c       |   39 +++++++++++++++++----------------------
>  fs/f2fs/node.c       |    1 -
>  fs/f2fs/recovery.c   |    2 --
>  fs/f2fs/segment.c    |    2 +-
>  5 files changed, 18 insertions(+), 27 deletions(-)
> 
> diff --git a/fs/f2fs/checkpoint.c b/fs/f2fs/checkpoint.c
> index fe91773..e376a42 100644
> --- a/fs/f2fs/checkpoint.c
> +++ b/fs/f2fs/checkpoint.c
> @@ -64,7 +64,6 @@ repeat:
>  	if (f2fs_readpage(sbi, page, index, READ_SYNC))
>  		goto repeat;
>  
> -	lock_page(page);
>  	if (page->mapping != mapping) {
>  		f2fs_put_page(page, 1);
>  		goto repeat;
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index 19cd7c6..b048936 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -216,13 +216,11 @@ struct page *find_data_page(struct inode *inode, pgoff_t index, bool sync)
>  
>  	err = f2fs_readpage(sbi, page, dn.data_blkaddr,
>  					sync ? READ_SYNC : READA);
> -	if (sync) {
> -		wait_on_page_locked(page);
> -		if (!PageUptodate(page)) {
> -			f2fs_put_page(page, 0);
> -			return ERR_PTR(-EIO);
> -		}
> -	}
> +	if (err)
> +		return ERR_PTR(err);
> +
> +	if (sync)
> +		unlock_page(page);
>  	return page;
>  }
>  
> @@ -267,11 +265,6 @@ repeat:
>  	if (err)
>  		return ERR_PTR(err);
>  
> -	lock_page(page);
> -	if (!PageUptodate(page)) {
> -		f2fs_put_page(page, 1);
> -		return ERR_PTR(-EIO);
> -	}
>  	if (page->mapping != mapping) {
>  		f2fs_put_page(page, 1);
>  		goto repeat;
> @@ -325,11 +318,7 @@ repeat:
>  		err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
>  		if (err)
>  			return ERR_PTR(err);
> -		lock_page(page);
> -		if (!PageUptodate(page)) {
> -			f2fs_put_page(page, 1);
> -			return ERR_PTR(-EIO);
> -		}
> +
>  		if (page->mapping != mapping) {
>  			f2fs_put_page(page, 1);
>  			goto repeat;
> @@ -399,6 +388,16 @@ int f2fs_readpage(struct f2fs_sb_info *sbi, struct page *page,
>  
>  	submit_bio(type, bio);
>  	up_read(&sbi->bio_sem);
> +
> +	if (type == READ_SYNC) {
> +		wait_on_page_locked(page);
> +		lock_page(page);
> +		if (!PageUptodate(page)) {
> +			f2fs_put_page(page, 1);
> +			return -EIO;
> +		}
> +	}
> +
>  	return 0;
>  }
>  
> @@ -679,11 +678,7 @@ repeat:
>  		err = f2fs_readpage(sbi, page, dn.data_blkaddr, READ_SYNC);
>  		if (err)
>  			return err;
> -		lock_page(page);
> -		if (!PageUptodate(page)) {
> -			f2fs_put_page(page, 1);
> -			return -EIO;
> -		}
> +
>  		if (page->mapping != mapping) {
>  			f2fs_put_page(page, 1);
>  			goto repeat;
> diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c
> index f5172e2..f061554 100644
> --- a/fs/f2fs/node.c
> +++ b/fs/f2fs/node.c
> @@ -1534,7 +1534,6 @@ int restore_node_summary(struct f2fs_sb_info *sbi,
>  		if (f2fs_readpage(sbi, page, addr, READ_SYNC))
>  			goto out;
>  
> -		lock_page(page);
>  		rn = F2FS_NODE(page);
>  		sum_entry->nid = rn->footer.nid;
>  		sum_entry->version = 0;
> diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
> index 639eb34..ec68183 100644
> --- a/fs/f2fs/recovery.c
> +++ b/fs/f2fs/recovery.c
> @@ -140,8 +140,6 @@ static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head)
>  		if (err)
>  			goto out;
>  
> -		lock_page(page);
> -
>  		if (cp_ver != cpver_of_node(page))
>  			break;
>  
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 9b74ae2..bcd19db 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -639,7 +639,7 @@ static void do_submit_bio(struct f2fs_sb_info *sbi,
>  
>  		trace_f2fs_do_submit_bio(sbi->sb, btype, sync, sbi->bio[btype]);
>  
> -		if (type == META_FLUSH) {
> +		if ((type == META_FLUSH) || (rw & WRITE_SYNC)) {
>  			DECLARE_COMPLETION_ONSTACK(wait);
>  			p->is_sync = true;
>  			p->wait = &wait;

-- 
Jaegeuk Kim
Samsung

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