linux-ext4 - Re: [PATCH V12 02/20] btrfs: look at bi

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Message-ID: <20181126224608.GO30411@vader>
Date:   Mon, 26 Nov 2018 14:46:08 -0800
From:   Omar Sandoval <osandov@...ndov.com>
To:     Ming Lei <ming.lei@...hat.com>
Cc:     Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Theodore Ts'o <tytso@....edu>, Omar Sandoval <osandov@...com>,
        Sagi Grimberg <sagi@...mberg.me>,
        Dave Chinner <dchinner@...hat.com>,
        Kent Overstreet <kent.overstreet@...il.com>,
        Mike Snitzer <snitzer@...hat.com>, dm-devel@...hat.com,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel@...r.kernel.org, Shaohua Li <shli@...nel.org>,
        linux-raid@...r.kernel.org, David Sterba <dsterba@...e.com>,
        linux-btrfs@...r.kernel.org,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        linux-xfs@...r.kernel.org, Gao Xiang <gaoxiang25@...wei.com>,
        Christoph Hellwig <hch@....de>, linux-ext4@...r.kernel.org,
        Coly Li <colyli@...e.de>, linux-bcache@...r.kernel.org,
        Boaz Harrosh <ooo@...ctrozaur.com>,
        Bob Peterson <rpeterso@...hat.com>, cluster-devel@...hat.com
Subject: Re: [PATCH V12 02/20] btrfs: look at bi_size for repair decisions

On Mon, Nov 26, 2018 at 10:17:02AM +0800, Ming Lei wrote:
> From: Christoph Hellwig <hch@....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@...e.com>

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

> Signed-off-by: Christoph Hellwig <hch@....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
>