diff mbox

[07/12] dm: use bvec iterator helpers to implement .get_page and .next_page

Message ID 1478865957-25252-8-git-send-email-tom.leiming@gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Ming Lei Nov. 11, 2016, 12:05 p.m. UTC
Firstly we have mature bvec/bio iterator helper for iterate each
page in one bio, not necessary to reinvent a wheel to do that.

Secondly the coming multipage bvecs requires this patch.

Also add comments about the direct access to bvec table.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
---
 drivers/md/dm-io.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

Comments

Ming Lei Nov. 15, 2016, 1:01 a.m. UTC | #1
On Fri, Nov 11, 2016 at 8:05 PM, Ming Lei <tom.leiming@gmail.com> wrote:
> Firstly we have mature bvec/bio iterator helper for iterate each
> page in one bio, not necessary to reinvent a wheel to do that.
>
> Secondly the coming multipage bvecs requires this patch.
>
> Also add comments about the direct access to bvec table.
>
> Signed-off-by: Ming Lei <tom.leiming@gmail.com>
> ---
>  drivers/md/dm-io.c | 34 ++++++++++++++++++++++++----------
>  1 file changed, 24 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
> index 0bf1a12e35fe..2ef573c220fc 100644
> --- a/drivers/md/dm-io.c
> +++ b/drivers/md/dm-io.c
> @@ -162,7 +162,10 @@ struct dpages {
>                          struct page **p, unsigned long *len, unsigned *offset);
>         void (*next_page)(struct dpages *dp);
>
> -       unsigned context_u;
> +       union {
> +               unsigned context_u;
> +               struct bvec_iter context_bi;
> +       };
>         void *context_ptr;
>
>         void *vma_invalidate_address;
> @@ -204,25 +207,36 @@ static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offse
>  static void bio_get_page(struct dpages *dp, struct page **p,
>                          unsigned long *len, unsigned *offset)
>  {
> -       struct bio_vec *bvec = dp->context_ptr;
> -       *p = bvec->bv_page;
> -       *len = bvec->bv_len - dp->context_u;
> -       *offset = bvec->bv_offset + dp->context_u;
> +       struct bio_vec bv = bvec_iter_bvec((struct bio_vec *)dp->context_ptr,
> +                       dp->context_bi);
> +
> +       *p = bv.bv_page;
> +       *len = bv.bv_len;
> +       *offset = bv.bv_offset;
> +
> +       /* avoid to figure out it in bio_next_page() again */
> +       dp->context_bi.bi_sector = (sector_t)bv.bv_len;
>  }
>
>  static void bio_next_page(struct dpages *dp)
>  {
> -       struct bio_vec *bvec = dp->context_ptr;
> -       dp->context_ptr = bvec + 1;
> -       dp->context_u = 0;
> +       unsigned int len = (unsigned int)dp->context_bi.bi_sector;
> +
> +       bvec_iter_advance((struct bio_vec *)dp->context_ptr,
> +                       &dp->context_bi, len);
>  }
>
>  static void bio_dp_init(struct dpages *dp, struct bio *bio)
>  {
>         dp->get_page = bio_get_page;
>         dp->next_page = bio_next_page;
> -       dp->context_ptr = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
> -       dp->context_u = bio->bi_iter.bi_bvec_done;
> +
> +       /*
> +        * We just use bvec iterator to retrieve pages, so it is ok to
> +        * access the bvec table directly here
> +        */
> +       dp->context_ptr = bio->bi_io_vec;
> +       dp->context_bi = bio->bi_iter;
>  }

Hi Alasdair, Mike, Christoph and anyone,

Could you give this one a review?

From my test, it just works fine, and I believe it is a good cleanup.

Thanks,
Ming Lei
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Christoph Hellwig Nov. 15, 2016, 6:55 p.m. UTC | #2
> Hi Alasdair, Mike, Christoph and anyone,
> 
> Could you give this one a review?

It looks nice, but I don't understand the code anywhere near well
enough to review it.  We'll need someone from the DM to look over it.
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Mike Snitzer Nov. 15, 2016, 6:57 p.m. UTC | #3
On Tue, Nov 15 2016 at  1:55pm -0500,
Christoph Hellwig <hch@infradead.org> wrote:

> > Hi Alasdair, Mike, Christoph and anyone,
> > 
> > Could you give this one a review?
> 
> It looks nice, but I don't understand the code anywhere near well
> enough to review it.  We'll need someone from the DM to look over it.

I'll try to get to it this week.
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Mike Snitzer Nov. 21, 2016, 2:49 p.m. UTC | #4
On Fri, Nov 11 2016 at  7:05am -0500,
Ming Lei <tom.leiming@gmail.com> wrote:

> Firstly we have mature bvec/bio iterator helper for iterate each
> page in one bio, not necessary to reinvent a wheel to do that.
> 
> Secondly the coming multipage bvecs requires this patch.
> 
> Also add comments about the direct access to bvec table.
> 
> Signed-off-by: Ming Lei <tom.leiming@gmail.com>

I've staged this for 4.10
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Ming Lei Nov. 22, 2016, 12:26 a.m. UTC | #5
On Mon, Nov 21, 2016 at 10:49 PM, Mike Snitzer <snitzer@redhat.com> wrote:
> On Fri, Nov 11 2016 at  7:05am -0500,
> Ming Lei <tom.leiming@gmail.com> wrote:
>
>> Firstly we have mature bvec/bio iterator helper for iterate each
>> page in one bio, not necessary to reinvent a wheel to do that.
>>
>> Secondly the coming multipage bvecs requires this patch.
>>
>> Also add comments about the direct access to bvec table.
>>
>> Signed-off-by: Ming Lei <tom.leiming@gmail.com>
>
> I've staged this for 4.10

Thanks Mike!
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Christoph Hellwig Nov. 22, 2016, 7:28 a.m. UTC | #6
Jens, can you apply the non-dm patches?
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diff mbox

Patch

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 0bf1a12e35fe..2ef573c220fc 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -162,7 +162,10 @@  struct dpages {
 			 struct page **p, unsigned long *len, unsigned *offset);
 	void (*next_page)(struct dpages *dp);
 
-	unsigned context_u;
+	union {
+		unsigned context_u;
+		struct bvec_iter context_bi;
+	};
 	void *context_ptr;
 
 	void *vma_invalidate_address;
@@ -204,25 +207,36 @@  static void list_dp_init(struct dpages *dp, struct page_list *pl, unsigned offse
 static void bio_get_page(struct dpages *dp, struct page **p,
 			 unsigned long *len, unsigned *offset)
 {
-	struct bio_vec *bvec = dp->context_ptr;
-	*p = bvec->bv_page;
-	*len = bvec->bv_len - dp->context_u;
-	*offset = bvec->bv_offset + dp->context_u;
+	struct bio_vec bv = bvec_iter_bvec((struct bio_vec *)dp->context_ptr,
+			dp->context_bi);
+
+	*p = bv.bv_page;
+	*len = bv.bv_len;
+	*offset = bv.bv_offset;
+
+	/* avoid to figure out it in bio_next_page() again */
+	dp->context_bi.bi_sector = (sector_t)bv.bv_len;
 }
 
 static void bio_next_page(struct dpages *dp)
 {
-	struct bio_vec *bvec = dp->context_ptr;
-	dp->context_ptr = bvec + 1;
-	dp->context_u = 0;
+	unsigned int len = (unsigned int)dp->context_bi.bi_sector;
+
+	bvec_iter_advance((struct bio_vec *)dp->context_ptr,
+			&dp->context_bi, len);
 }
 
 static void bio_dp_init(struct dpages *dp, struct bio *bio)
 {
 	dp->get_page = bio_get_page;
 	dp->next_page = bio_next_page;
-	dp->context_ptr = __bvec_iter_bvec(bio->bi_io_vec, bio->bi_iter);
-	dp->context_u = bio->bi_iter.bi_bvec_done;
+
+	/*
+	 * We just use bvec iterator to retrieve pages, so it is ok to
+	 * access the bvec table directly here
+	 */
+	dp->context_ptr = bio->bi_io_vec;
+	dp->context_bi = bio->bi_iter;
 }
 
 /*