Re: [RFC PATCH 15/17] fs: use helper bio_add_page() instead of open coding on bi_io_vec

[Dave Kleikamp <dave.kleikamp@oracle.com>]

On 12/22/2014 05:48 AM, Dongsu Park wrote:
> From: Kent Overstreet <kmo@daterainc.com>
> 
> Call pre-defined helper bio_add_page() instead of open coding for
> iterating through bi_io_vec[]. Doing that, it's possible to make some
> parts in filesystems and mm/page_io.c simpler than before.
> 
> Signed-off-by: Kent Overstreet <kmo@daterainc.com>
> [dpark: add more description in commit message]
> Signed-off-by: Dongsu Park <dongsu.park@profitbricks.com>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: Dave Kleikamp <shaggy@kernel.org>

Acked-by: Dave Kleikamp <dave.kleikamp@oracle.com>

> Cc: linux-fsdevel@vger.kernel.org
> ---
>  fs/buffer.c         |  7 ++-----
>  fs/jfs/jfs_logmgr.c | 14 ++++----------
>  mm/page_io.c        |  8 +++-----
>  3 files changed, 9 insertions(+), 20 deletions(-)
> 
> diff --git a/fs/buffer.c b/fs/buffer.c
> index 20805db..35ac0ec 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -3022,12 +3022,9 @@ int _submit_bh(int rw, struct buffer_head *bh, unsigned long bio_flags)
>  
>  	bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
>  	bio->bi_bdev = bh->b_bdev;
> -	bio->bi_io_vec[0].bv_page = bh->b_page;
> -	bio->bi_io_vec[0].bv_len = bh->b_size;
> -	bio->bi_io_vec[0].bv_offset = bh_offset(bh);
>  
> -	bio->bi_vcnt = 1;
> -	bio->bi_iter.bi_size = bh->b_size;
> +	bio_add_page(bio, bh->b_page, bh->b_size, bh_offset(bh));
> +	BUG_ON(bio->bi_iter.bi_size != bh->b_size);
>  
>  	bio->bi_end_io = end_bio_bh_io_sync;
>  	bio->bi_private = bh;
> diff --git a/fs/jfs/jfs_logmgr.c b/fs/jfs/jfs_logmgr.c
> index bc462dc..46fae06 100644
> --- a/fs/jfs/jfs_logmgr.c
> +++ b/fs/jfs/jfs_logmgr.c
> @@ -1999,12 +1999,9 @@ static int lbmRead(struct jfs_log * log, int pn, struct lbuf ** bpp)
>  
>  	bio->bi_iter.bi_sector = bp->l_blkno << (log->l2bsize - 9);
>  	bio->bi_bdev = log->bdev;
> -	bio->bi_io_vec[0].bv_page = bp->l_page;
> -	bio->bi_io_vec[0].bv_len = LOGPSIZE;
> -	bio->bi_io_vec[0].bv_offset = bp->l_offset;
>  
> -	bio->bi_vcnt = 1;
> -	bio->bi_iter.bi_size = LOGPSIZE;
> +	bio_add_page(bio, bp->l_page, LOGPSIZE, bp->l_offset);
> +	BUG_ON(bio->bi_iter.bi_size != LOGPSIZE);
>  
>  	bio->bi_end_io = lbmIODone;
>  	bio->bi_private = bp;
> @@ -2145,12 +2142,9 @@ static void lbmStartIO(struct lbuf * bp)
>  	bio = bio_alloc(GFP_NOFS, 1);
>  	bio->bi_iter.bi_sector = bp->l_blkno << (log->l2bsize - 9);
>  	bio->bi_bdev = log->bdev;
> -	bio->bi_io_vec[0].bv_page = bp->l_page;
> -	bio->bi_io_vec[0].bv_len = LOGPSIZE;
> -	bio->bi_io_vec[0].bv_offset = bp->l_offset;
>  
> -	bio->bi_vcnt = 1;
> -	bio->bi_iter.bi_size = LOGPSIZE;
> +	bio_add_page(bio, bp->l_page, LOGPSIZE, bp->l_offset);
> +	BUG_ON(bio->bi_iter.bi_size != LOGPSIZE);
>  
>  	bio->bi_end_io = lbmIODone;
>  	bio->bi_private = bp;
> diff --git a/mm/page_io.c b/mm/page_io.c
> index 955db8b..8c878c7 100644
> --- a/mm/page_io.c
> +++ b/mm/page_io.c
> @@ -33,12 +33,10 @@ static struct bio *get_swap_bio(gfp_t gfp_flags,
>  	if (bio) {
>  		bio->bi_iter.bi_sector = map_swap_page(page, &bio->bi_bdev);
>  		bio->bi_iter.bi_sector <<= PAGE_SHIFT - 9;
> -		bio->bi_io_vec[0].bv_page = page;
> -		bio->bi_io_vec[0].bv_len = PAGE_SIZE;
> -		bio->bi_io_vec[0].bv_offset = 0;
> -		bio->bi_vcnt = 1;
> -		bio->bi_iter.bi_size = PAGE_SIZE;
>  		bio->bi_end_io = end_io;
> +
> +		bio_add_page(bio, page, PAGE_SIZE, 0);
> +		BUG_ON(bio->bi_iter.bi_size != PAGE_SIZE);
>  	}
>  	return bio;
>  }
>