[PATCH 17/27] dm: crypt: use bio_add_page()

[PATCH 17/27] dm: crypt: use bio_add_page()

[Ming Lei]

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
---
 drivers/md/dm-crypt.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 4f3cb35..a2805c1 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -995,7 +995,6 @@ static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size)
 	gfp_t gfp_mask = GFP_NOWAIT | __GFP_HIGHMEM;
 	unsigned i, len, remaining_size;
 	struct page *page;
-	struct bio_vec *bvec;
 
 retry:
 	if (unlikely(gfp_mask & __GFP_DIRECT_RECLAIM))
@@ -1020,12 +1019,7 @@ retry:
 
 		len = (remaining_size > PAGE_SIZE) ? PAGE_SIZE : remaining_size;
 
-		bvec = &clone->bi_io_vec[clone->bi_vcnt++];
-		bvec->bv_page = page;
-		bvec->bv_len = len;
-		bvec->bv_offset = 0;
-
-		clone->bi_iter.bi_size += len;
+		bio_add_page(clone, page, len, 0);
 
 		remaining_size -= len;
 	}
-- 
1.9.1

[PATCH 18/27] dm: dm-io.c: use bio_get_base_vec()

[Ming Lei]

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
---
 drivers/md/dm-io.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 06d426e..6b0e466 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -221,7 +221,12 @@ 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);
+
+	/*
+	 * need to fix both bio_get_page() and bio_next_page()
+	 * before multipage bvecs
+	 */
+	dp->context_ptr = bio_get_base_vec(bio);
 	dp->context_u = bio->bi_iter.bi_bvec_done;
 }
 
-- 
1.9.1

[PATCH 19/27] dm: dm.c: replace 'bio->bi_vcnt == 1' with !bio_multiple_segments

[Ming Lei]

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
---
 drivers/md/dm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index be49057..4c34f88 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2172,7 +2172,8 @@ static void dm_request_fn(struct request_queue *q)
 			pos = blk_rq_pos(rq);
 
 		if ((dm_request_peeked_before_merge_deadline(md) &&
-		     md_in_flight(md) && rq->bio && rq->bio->bi_vcnt == 1 &&
+		     md_in_flight(md) && rq->bio &&
+		     !bio_multiple_segments(rq->bio) &&
 		     md->last_rq_pos == pos && md->last_rq_rw == rq_data_dir(rq)) ||
 		    (ti->type->busy && ti->type->busy(ti))) {
 			blk_delay_queue(q, HZ / 100);
-- 
1.9.1

[PATCH 20/27] dm: dm-bufio.c: use bio_set_vec_table()

[Ming Lei]

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
---
 drivers/md/dm-bufio.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index cd77216..0e48ad7 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -624,8 +624,7 @@ static void use_inline_bio(struct dm_buffer *b, int rw, sector_t block,
 	int len;
 
 	bio_init(&b->bio);
-	b->bio.bi_io_vec = b->bio_vec;
-	b->bio.bi_max_vecs = DM_BUFIO_INLINE_VECS;
+	bio_set_vec_table(&b->bio, b->bio_vec, DM_BUFIO_INLINE_VECS);
 	b->bio.bi_iter.bi_sector = block << b->c->sectors_per_block_bits;
 	b->bio.bi_bdev = b->c->bdev;
 	b->bio.bi_end_io = inline_endio;
-- 
1.9.1

Re: [PATCH 17/27] dm: crypt: use bio_add_page()

[Christoph Hellwig]

Looks fine,

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH 20/27] dm: dm-bufio.c: use bio_set_vec_table()

[Christoph Hellwig]

On Tue, Apr 05, 2016 at 08:07:35PM +0800, Ming Lei wrote:
> Signed-off-by: Ming Lei <tom.leiming@gmail.com>
> ---
>  drivers/md/dm-bufio.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
> index cd77216..0e48ad7 100644
> --- a/drivers/md/dm-bufio.c
> +++ b/drivers/md/dm-bufio.c
> @@ -624,8 +624,7 @@ static void use_inline_bio(struct dm_buffer *b, int rw, sector_t block,
>  	int len;
>  
>  	bio_init(&b->bio);
> -	b->bio.bi_io_vec = b->bio_vec;
> -	b->bio.bi_max_vecs = DM_BUFIO_INLINE_VECS;
> +	bio_set_vec_table(&b->bio, b->bio_vec, DM_BUFIO_INLINE_VECS);
>  	b->bio.bi_iter.bi_sector = block << b->c->sectors_per_block_bits;
>  	b->bio.bi_bdev = b->c->bdev;
>  	b->bio.bi_end_io = inline_endio;

Should be switched to use bio_alloc instead.

Re: [PATCH 20/27] dm: dm-bufio.c: use bio_set_vec_table()

[Mike Snitzer]

On Tue, Apr 05 2016 at  9:04am -0400,
Christoph Hellwig <hch@infradead.org> wrote:

> On Tue, Apr 05, 2016 at 08:07:35PM +0800, Ming Lei wrote:
> > Signed-off-by: Ming Lei <tom.leiming@gmail.com>
> > ---
> >  drivers/md/dm-bufio.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> > 
> > diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
> > index cd77216..0e48ad7 100644
> > --- a/drivers/md/dm-bufio.c
> > +++ b/drivers/md/dm-bufio.c
> > @@ -624,8 +624,7 @@ static void use_inline_bio(struct dm_buffer *b, int rw, sector_t block,
> >  	int len;
> >  
> >  	bio_init(&b->bio);
> > -	b->bio.bi_io_vec = b->bio_vec;
> > -	b->bio.bi_max_vecs = DM_BUFIO_INLINE_VECS;
> > +	bio_set_vec_table(&b->bio, b->bio_vec, DM_BUFIO_INLINE_VECS);
> >  	b->bio.bi_iter.bi_sector = block << b->c->sectors_per_block_bits;
> >  	b->bio.bi_bdev = b->c->bdev;
> >  	b->bio.bi_end_io = inline_endio;
> 
> Should be switched to use bio_alloc instead.

Why does the use of bio_init() vs bio_alloc() bother you?

'struct dm_buffer' has a 'struct bio'.  That bio is allocated as part of
the dm_buffer in drivers/md/dmbufio.c:alloc_buffer() -- which is called
by various other bufio interfaces (e.g. __alloc_buffer_wait).  Bufio is
in control of ensuring forward progress by carefully managing the memory
associated with these buffers.  I don't see the benefit of bio_alloc()
here.  What am I missing?