linux-kernel - Re: [f2fs-dev] [PATCH 4/4] f2fs: should check the type of end

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Date:   Mon, 9 Jul 2018 22:54:15 +0800
From:   Chao Yu <chao@...nel.org>
To:     Jaegeuk Kim <jaegeuk@...nel.org>, linux-kernel@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 4/4] f2fs: should check the type of end_io
 after pullback by fscrypto

On 2018/7/7 5:09, Jaegeuk Kim wrote:
> This fixes to get the page type after pullback by fscrypto, since the original
> page is bounce page but we should need to get control page which is what we
> originally submitted.
> 
> Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> ---
>  fs/f2fs/data.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
> index c3f9b9baf140..9a0fcec53d0e 100644
> --- a/fs/f2fs/data.c
> +++ b/fs/f2fs/data.c
> @@ -152,7 +152,6 @@ static void f2fs_write_end_io(struct bio *bio)
>  
>  	bio_for_each_segment_all(bvec, bio, i) {
>  		struct page *page = bvec->bv_page;
> -		enum count_type type = WB_DATA_TYPE(page);
>  
>  		if (IS_DUMMY_WRITTEN_PAGE(page)) {
>  			set_page_private(page, (unsigned long)NULL);
> @@ -169,14 +168,14 @@ static void f2fs_write_end_io(struct bio *bio)
>  
>  		if (unlikely(bio->bi_status)) {
>  			mapping_set_error(page->mapping, -EIO);
> -			if (type == F2FS_WB_CP_DATA)
> +			if (WB_DATA_TYPE(page) == F2FS_WB_CP_DATA)
>  				f2fs_stop_checkpoint(sbi, true);
>  		}
>  
>  		f2fs_bug_on(sbi, page->mapping == NODE_MAPPING(sbi) &&
>  					page->index != nid_of_node(page));
>  
> -		dec_page_count(sbi, type);
> +		dec_page_count(sbi, WB_DATA_TYPE(page));

But we account F2FS_WB_CP_DATA/F2FS_WB_DATA type page based bounce page instead
of original page.

	bio_page = fio->encrypted_page ? fio->encrypted_page : fio->page;

	/* set submitted = true as a return value */
	fio->submitted = true;

	inc_page_count(sbi, WB_DATA_TYPE(bio_page));

Because for encrypted page of regular inode, we should account it with
F2FS_WB_DATA type:

static bool __is_cp_guaranteed(struct page *page)
{
....
	if (!mapping)   <---bounce page's mapping is NULL
		return false;
}

So we will get F2FS_WB_DATA type from __is_cp_guaranteed below:

enum count_type type = WB_DATA_TYPE(page);

Is there any problem?

Thanks

>  		clear_cold_data(page);
>  		end_page_writeback(page);
>  	}
>