[PATCH v2 11/51] md: raid1: initialize bvec table via bio_add_page()

[PATCH v2 11/51] md: raid1: initialize bvec table via bio_add_page()

[Ming Lei]

We will support multipage bvec soon, so initialize bvec
table using the standardy way instead of writing the
talbe directly. Otherwise it won't work any more once
multipage bvec is enabled.

Cc: Shaohua Li <shli@kernel.org>
Cc: linux-raid@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/md/raid1.c | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 3febfc8391fb..835c42396861 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2086,10 +2086,8 @@ 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 +2096,6 @@ 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 +2103,20 @@ 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 */
+		rp->idx = 0;
+		size = r1_bio->sectors << 9;
+		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(b, page, len, 0);
+			size -= len;
+		} while (rp->idx < RESYNC_PAGES && size > 0);
 	}
 	for (primary = 0; primary < conf->raid_disks * 2; primary++)
 		if (r1_bio->bios[primary]->bi_end_io == end_sync_read &&
-- 
2.9.4

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[PATCH v2 12/51] md: raid10: avoid to access bvec table directly

[Ming Lei]

Inside sync_request_write(), .bi_vcnt is written after this bio
is reseted, this way won't work any more after multipage bvec
is enabled.

So reset_bvec_table() is introduced for re-add these pages into
bio, then .bi_vcnt needn't to be touched any more.

Cc: Shaohua Li <shli@kernel.org>
Cc: linux-raid@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/md/raid10.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 5026e7ad51d3..2fca1fe67092 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1995,6 +1995,24 @@ static void end_sync_write(struct bio *bio)
 	end_sync_request(r10_bio);
 }
 
+/* called after bio_reset() */
+static 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);
+}
+
 /*
  * Note: sync and recover and handled very differently for raid10
  * This code is for resync.
@@ -2087,8 +2105,8 @@ 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;
-- 
2.9.4

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[PATCH v2 36/51] md: raid1: convert to bio_for_each_segment_all_sp()

[Ming Lei]

Cc: Shaohua Li <shli@kernel.org>
Cc: linux-raid@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/md/raid1.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 835c42396861..ca4b9ff8d39b 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -2135,13 +2135,14 @@ static void process_checks(struct r1bio *r1_bio)
 		struct page **spages = get_resync_pages(sbio)->pages;
 		struct bio_vec *bi;
 		int page_len[RESYNC_PAGES] = { 0 };
+		struct bvec_iter_all bia;
 
 		if (sbio->bi_end_io != end_sync_read)
 			continue;
 		/* Now we can 'fixup' the error value */
 		sbio->bi_status = 0;
 
-		bio_for_each_segment_all(bi, sbio, j)
+		bio_for_each_segment_all_sp(bi, sbio, j, bia)
 			page_len[j] = bi->bv_len;
 
 		if (!status) {
-- 
2.9.4

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Re: [PATCH v2 11/51] md: raid1: initialize bvec table via bio_add_page()

[Guoqing Jiang]

On 06/26/2017 08:09 PM, Ming Lei wrote:
> We will support multipage bvec soon, so initialize bvec
> table using the standardy way instead of writing the
> talbe directly. Otherwise it won't work any more once
> multipage bvec is enabled.
>
> Cc: Shaohua Li <shli@kernel.org>
> Cc: linux-raid@vger.kernel.org
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>   drivers/md/raid1.c | 27 ++++++++++++++-------------
>   1 file changed, 14 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 3febfc8391fb..835c42396861 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -2086,10 +2086,8 @@ 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 +2096,6 @@ 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 +2103,20 @@ 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 */
> +		rp->idx = 0;
> +		size = r1_bio->sectors << 9;
> +		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(b, page, len, 0);
> +			size -= len;
> +		} while (rp->idx < RESYNC_PAGES && size > 0);
>   	}

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.

Thanks,
Guoqing

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Re: [PATCH v2 11/51] md: raid1: initialize bvec table via bio_add_page()

[Ming Lei]

On Tue, Jun 27, 2017 at 05:36:39PM +0800, Guoqing Jiang wrote:
> 
> 
> On 06/26/2017 08:09 PM, Ming Lei wrote:
> > We will support multipage bvec soon, so initialize bvec
> > table using the standardy way instead of writing the
> > talbe directly. Otherwise it won't work any more once
> > multipage bvec is enabled.
> > 
> > Cc: Shaohua Li <shli@kernel.org>
> > Cc: linux-raid@vger.kernel.org
> > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > ---
> >   drivers/md/raid1.c | 27 ++++++++++++++-------------
> >   1 file changed, 14 insertions(+), 13 deletions(-)
> > 
> > diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> > index 3febfc8391fb..835c42396861 100644
> > --- a/drivers/md/raid1.c
> > +++ b/drivers/md/raid1.c
> > @@ -2086,10 +2086,8 @@ 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 +2096,6 @@ 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 +2103,20 @@ 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 */
> > +		rp->idx = 0;
> > +		size = r1_bio->sectors << 9;
> > +		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(b, page, len, 0);
> > +			size -= len;
> > +		} while (rp->idx < RESYNC_PAGES && size > 0);
> >   	}
> 
> 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?

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

Re: [PATCH v2 11/51] md: raid1: initialize bvec table via bio_add_page()

[Guoqing Jiang]

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@suse.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
>

Re: [PATCH v2 11/51] md: raid1: initialize bvec table via bio_add_page()

[Shaohua Li]

On Wed, Jun 28, 2017 at 12:22:51AM +0800, Ming Lei wrote:
> On Tue, Jun 27, 2017 at 05:36:39PM +0800, Guoqing Jiang wrote:
> > 
> > 
> > On 06/26/2017 08:09 PM, Ming Lei wrote:
> > > We will support multipage bvec soon, so initialize bvec
> > > table using the standardy way instead of writing the
> > > talbe directly. Otherwise it won't work any more once
> > > multipage bvec is enabled.
> > > 
> > > Cc: Shaohua Li <shli@kernel.org>
> > > Cc: linux-raid@vger.kernel.org
> > > Signed-off-by: Ming Lei <ming.lei@redhat.com>
> > > ---
> > >   drivers/md/raid1.c | 27 ++++++++++++++-------------
> > >   1 file changed, 14 insertions(+), 13 deletions(-)
> > > 
> > > diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> > > index 3febfc8391fb..835c42396861 100644
> > > --- a/drivers/md/raid1.c
> > > +++ b/drivers/md/raid1.c
> > > @@ -2086,10 +2086,8 @@ 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 +2096,6 @@ 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 +2103,20 @@ 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 */
> > > +		rp->idx = 0;
> > > +		size = r1_bio->sectors << 9;
> > > +		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(b, page, len, 0);
> > > +			size -= len;
> > > +		} while (rp->idx < RESYNC_PAGES && size > 0);
> > >   	}
> > 
> > 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?
> 
> Shaohua, what do you think of this one?

generally looks good.
 
> ---
> 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);
> +}
> +

used in raid1/10, so must export the symbol. Then please not pollute global
names, maybe call it md_bio_reset_resync_pages?

>  #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