linux-kernel - Re: [PATCH v2 11/51] md: raid1: initialize bvec table via bio_add

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Date:   Thu, 29 Jun 2017 09:36:31 +0800
From:   Guoqing Jiang <gqjiang@...e.com>
To:     Ming Lei <ming.lei@...hat.com>
Cc:     Jens Axboe <axboe@...com>, Christoph Hellwig <hch@...radead.org>,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org,
        Shaohua Li <shli@...nel.org>, linux-raid@...r.kernel.org
Subject: Re: [PATCH v2 11/51] md: raid1: initialize bvec table via
 bio_add_page()



On 06/28/2017 12:22 AM, Ming Lei wrote:
>
>> Seems above section is similar as reset_bvec_table introduced in next patch,
>> why there is difference between raid1 and raid10? Maybe add reset_bvec_table
>> into md.c, then call it in raid1 or raid10 is better, just my 2 cents.
> Hi Guoqing,
>
> I think it is a good idea, and even the two patches can be put into
> one, so how about the following patch?

Looks good.

Acked-by: Guoqing Jiang <gqjiang@...e.com>

Thanks,
Guoqing

>
> Shaohua, what do you think of this one?
>
> ---
> diff --git a/drivers/md/md.c b/drivers/md/md.c
> index 3d957ac1e109..7ffc622dd7fa 100644
> --- a/drivers/md/md.c
> +++ b/drivers/md/md.c
> @@ -9126,6 +9126,24 @@ void md_reload_sb(struct mddev *mddev, int nr)
>   }
>   EXPORT_SYMBOL(md_reload_sb);
>   
> +/* generally called after bio_reset() for reseting bvec */
> +void reset_bvec_table(struct bio *bio, struct resync_pages *rp, int size)
> +{
> +	/* initialize bvec table again */
> +	rp->idx = 0;
> +	do {
> +		struct page *page = resync_fetch_page(rp, rp->idx++);
> +		int len = min_t(int, size, PAGE_SIZE);
> +
> +		/*
> +		 * won't fail because the vec table is big
> +		 * enough to hold all these pages
> +		 */
> +		bio_add_page(bio, page, len, 0);
> +		size -= len;
> +	} while (rp->idx < RESYNC_PAGES && size > 0);
> +}
> +
>   #ifndef MODULE
>   
>   /*
> diff --git a/drivers/md/md.h b/drivers/md/md.h
> index 991f0fe2dcc6..f569831b1de9 100644
> --- a/drivers/md/md.h
> +++ b/drivers/md/md.h
> @@ -783,4 +783,6 @@ static inline struct page *resync_fetch_page(struct resync_pages *rp,
>   		return NULL;
>   	return rp->pages[idx];
>   }
> +
> +void reset_bvec_table(struct bio *bio, struct resync_pages *rp, int size);
>   #endif /* _MD_MD_H */
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 3febfc8391fb..6ae2665ecd58 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -2086,10 +2086,7 @@ static void process_checks(struct r1bio *r1_bio)
>   	/* Fix variable parts of all bios */
>   	vcnt = (r1_bio->sectors + PAGE_SIZE / 512 - 1) >> (PAGE_SHIFT - 9);
>   	for (i = 0; i < conf->raid_disks * 2; i++) {
> -		int j;
> -		int size;
>   		blk_status_t status;
> -		struct bio_vec *bi;
>   		struct bio *b = r1_bio->bios[i];
>   		struct resync_pages *rp = get_resync_pages(b);
>   		if (b->bi_end_io != end_sync_read)
> @@ -2098,8 +2095,6 @@ static void process_checks(struct r1bio *r1_bio)
>   		status = b->bi_status;
>   		bio_reset(b);
>   		b->bi_status = status;
> -		b->bi_vcnt = vcnt;
> -		b->bi_iter.bi_size = r1_bio->sectors << 9;
>   		b->bi_iter.bi_sector = r1_bio->sector +
>   			conf->mirrors[i].rdev->data_offset;
>   		b->bi_bdev = conf->mirrors[i].rdev->bdev;
> @@ -2107,15 +2102,8 @@ static void process_checks(struct r1bio *r1_bio)
>   		rp->raid_bio = r1_bio;
>   		b->bi_private = rp;
>   
> -		size = b->bi_iter.bi_size;
> -		bio_for_each_segment_all(bi, b, j) {
> -			bi->bv_offset = 0;
> -			if (size > PAGE_SIZE)
> -				bi->bv_len = PAGE_SIZE;
> -			else
> -				bi->bv_len = size;
> -			size -= PAGE_SIZE;
> -		}
> +		/* initialize bvec table again */
> +		reset_bvec_table(b, rp, r1_bio->sectors << 9);
>   	}
>   	for (primary = 0; primary < conf->raid_disks * 2; primary++)
>   		if (r1_bio->bios[primary]->bi_end_io == end_sync_read &&
> diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
> index 5026e7ad51d3..72f4fa07449b 100644
> --- a/drivers/md/raid10.c
> +++ b/drivers/md/raid10.c
> @@ -2087,8 +2087,8 @@ static void sync_request_write(struct mddev *mddev, struct r10bio *r10_bio)
>   		rp = get_resync_pages(tbio);
>   		bio_reset(tbio);
>   
> -		tbio->bi_vcnt = vcnt;
> -		tbio->bi_iter.bi_size = fbio->bi_iter.bi_size;
> +		reset_bvec_table(tbio, rp, fbio->bi_iter.bi_size);
> +
>   		rp->raid_bio = r10_bio;
>   		tbio->bi_private = rp;
>   		tbio->bi_iter.bi_sector = r10_bio->devs[i].addr;
>
> Thanks,
> Ming
>