Re: [f2fs-dev] [PATCH 4/4] f2fs: should check the type of end_io after pullback by fscrypto

[Jaegeuk Kim]

On 07/10, Jaegeuk Kim wrote:
> On 07/09, Chao Yu wrote:
> > 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@xxxxxxxxxx>
> > > ---
> > >  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?
> 
> Wait a minute.
> 
> 	bio_page = fio->encrypted_page ? fio->encrypted_page : fio->page;
> 
> 1. fio->encrypted_page
> 
> 	inc_page_count(sbi, F2FS_WB_CP_DATA); // page->mapping == META_MAPPING
> 
>   In write_end_io(),
> 	type = F2FS_WB_DATA; // page->mapping == NULL
> 	fscrypt_pullback_bio_page(&page);
> 	  page = fio->encrypted_page;
> 	
> 	dec_page_count(F2FS_WB_DATA);
> 
> 2. fio->page
> 
> 	inc_page_count(sbi, F2FS_WB_DATA);
> 
>   In write_end_io(),
> 	type = F2FS_WB_DATA; // page->mapping == NULL
> 	fscrypt_pullback_bio_page(&page);
> 	  page = fio->encrypted_page;
> 	
> 	dec_page_count(F2FS_WB_DATA);
> 
> Thoughts?

Oops, nvm. I was confused. :P

> 
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