Re: [PATCH V12 02/20] btrfs: look at bi_size for repair decisions

[Omar Sandoval <osandov@osandov.com>]

On Mon, Nov 26, 2018 at 10:17:02AM +0800, Ming Lei wrote:
> From: Christoph Hellwig <hch@lst.de>
> 
> bio_readpage_error currently uses bi_vcnt to decide if it is worth
> retrying an I/O.  But the vector count is mostly an implementation
> artifact - it really should figure out if there is more than a
> single sector worth retrying.  Use bi_size for that and shift by
> PAGE_SHIFT.  This really should be blocks/sectors, but given that
> btrfs doesn't support a sector size different from the PAGE_SIZE
> using the page size keeps the changes to a minimum.
> 
> Reviewed-by: David Sterba <dsterba@suse.com>

Reviewed-by: Omar Sandoval <osandov@fb.com>

> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/btrfs/extent_io.c | 2 +-
>  include/linux/bio.h  | 6 ------
>  2 files changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
> index 15fd46582bb2..40751e86a2a9 100644
> --- a/fs/btrfs/extent_io.c
> +++ b/fs/btrfs/extent_io.c
> @@ -2368,7 +2368,7 @@ static int bio_readpage_error(struct bio *failed_bio, u64 phy_offset,
>  	int read_mode = 0;
>  	blk_status_t status;
>  	int ret;
> -	unsigned failed_bio_pages = bio_pages_all(failed_bio);
> +	unsigned failed_bio_pages = failed_bio->bi_iter.bi_size >> PAGE_SHIFT;
>  
>  	BUG_ON(bio_op(failed_bio) == REQ_OP_WRITE);
>  
> diff --git a/include/linux/bio.h b/include/linux/bio.h
> index 056fb627edb3..6f6bc331a5d1 100644
> --- a/include/linux/bio.h
> +++ b/include/linux/bio.h
> @@ -263,12 +263,6 @@ static inline void bio_get_last_bvec(struct bio *bio, struct bio_vec *bv)
>  		bv->bv_len = iter.bi_bvec_done;
>  }
>  
> -static inline unsigned bio_pages_all(struct bio *bio)
> -{
> -	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
> -	return bio->bi_vcnt;
> -}
> -
>  static inline struct bio_vec *bio_first_bvec_all(struct bio *bio)
>  {
>  	WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED));
> -- 
> 2.9.5
>