diff mbox

[17/23] dm: Refactor for new bio cloning/splitting

Message ID 1383077896-4132-18-git-send-email-kmo@daterainc.com (mailing list archive)
State New, archived
Delegated to: Mike Snitzer
Headers show

Commit Message

Kent Overstreet Oct. 29, 2013, 8:18 p.m. UTC
We need to convert the dm code to the new bvec_iter primitives which
respect bi_bvec_done; they also allow us to drastically simplify dm's
bio splitting code.

Also kill bio_sector_offset(), dm was the only user and it doesn't make
much sense anymore.

Signed-off-by: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: dm-devel@redhat.com
---
 drivers/md/dm-thin.c |   8 ++-
 drivers/md/dm.c      | 170 ++++++---------------------------------------------
 fs/bio.c             |  38 ------------
 include/linux/bio.h  |   1 -
 4 files changed, 24 insertions(+), 193 deletions(-)

Comments

Mike Snitzer Oct. 29, 2013, 11:04 p.m. UTC | #1
On Tue, Oct 29 2013 at  4:18pm -0400,
Kent Overstreet <kmo@daterainc.com> wrote:

> We need to convert the dm code to the new bvec_iter primitives which
> respect bi_bvec_done; they also allow us to drastically simplify dm's
> bio splitting code.
> 
> Also kill bio_sector_offset(), dm was the only user and it doesn't make
> much sense anymore.
> 
> Signed-off-by: Kent Overstreet <kmo@daterainc.com>
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: Alasdair Kergon <agk@redhat.com>
> Cc: dm-devel@redhat.com

I reviewed this patch some weeks ago (along with the rest of the DM
changes), I provided the dm-thin.c changes in this patch:
http://www.redhat.com/archives/dm-devel/2013-October/msg00027.html

Please add:

Signed-off-by: Mike Snitzer <snitzer@redhat.com>

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Mike Snitzer Oct. 30, 2013, 12:09 a.m. UTC | #2
On Tue, Oct 29 2013 at  4:18pm -0400,
Kent Overstreet <kmo@daterainc.com> wrote:

> We need to convert the dm code to the new bvec_iter primitives which
> respect bi_bvec_done; they also allow us to drastically simplify dm's
> bio splitting code.
> 
> Also kill bio_sector_offset(), dm was the only user and it doesn't make
> much sense anymore.
> 
> Signed-off-by: Kent Overstreet <kmo@daterainc.com>
> Cc: Jens Axboe <axboe@kernel.dk>
> Cc: Alasdair Kergon <agk@redhat.com>
> Cc: dm-devel@redhat.com
> ---
>  drivers/md/dm-thin.c |   8 ++-
>  drivers/md/dm.c      | 170 ++++++---------------------------------------------
>  fs/bio.c             |  38 ------------
>  include/linux/bio.h  |   1 -
>  4 files changed, 24 insertions(+), 193 deletions(-)
> 
> diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
> index a654024..1abb4a2 100644
> --- a/drivers/md/dm-thin.c
> +++ b/drivers/md/dm-thin.c
> @@ -611,8 +611,10 @@ static void cell_defer_no_holder(struct thin_c *tc, struct dm_bio_prison_cell *c
>  
>  static void process_prepared_mapping_fail(struct dm_thin_new_mapping *m)
>  {
> -	if (m->bio)
> +	if (m->bio) {
>  		m->bio->bi_end_io = m->saved_bi_end_io;
> +		atomic_inc(&m->bio->bi_remaining);
> +	}
>  	cell_error(m->tc->pool, m->cell);
>  	list_del(&m->list);
>  	mempool_free(m, m->tc->pool->mapping_pool);
> @@ -626,8 +628,10 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
>  	int r;
>  
>  	bio = m->bio;
> -	if (bio)
> +	if (bio) {
>  		bio->bi_end_io = m->saved_bi_end_io;
> +		atomic_inc(&bio->bi_remaining);
> +	}
>  
>  	if (m->err) {
>  		cell_error(pool, m->cell);

But now that I look closer, the above dm-thin.c hunks belong in:
[PATCH 19/23] block: Generic bio chaining

Seems these changes were mistakenly folded into this 17/23 patch?

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Kent Overstreet Oct. 30, 2013, 12:19 a.m. UTC | #3
On Tue, Oct 29, 2013 at 08:09:08PM -0400, Mike Snitzer wrote:
> On Tue, Oct 29 2013 at  4:18pm -0400,
> Kent Overstreet <kmo@daterainc.com> wrote:
> 
> > We need to convert the dm code to the new bvec_iter primitives which
> > respect bi_bvec_done; they also allow us to drastically simplify dm's
> > bio splitting code.
> > 
> > Also kill bio_sector_offset(), dm was the only user and it doesn't make
> > much sense anymore.
> > 
> > Signed-off-by: Kent Overstreet <kmo@daterainc.com>
> > Cc: Jens Axboe <axboe@kernel.dk>
> > Cc: Alasdair Kergon <agk@redhat.com>
> > Cc: dm-devel@redhat.com
> > ---
> >  drivers/md/dm-thin.c |   8 ++-
> >  drivers/md/dm.c      | 170 ++++++---------------------------------------------
> >  fs/bio.c             |  38 ------------
> >  include/linux/bio.h  |   1 -
> >  4 files changed, 24 insertions(+), 193 deletions(-)
> > 
> > diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
> > index a654024..1abb4a2 100644
> > --- a/drivers/md/dm-thin.c
> > +++ b/drivers/md/dm-thin.c
> > @@ -611,8 +611,10 @@ static void cell_defer_no_holder(struct thin_c *tc, struct dm_bio_prison_cell *c
> >  
> >  static void process_prepared_mapping_fail(struct dm_thin_new_mapping *m)
> >  {
> > -	if (m->bio)
> > +	if (m->bio) {
> >  		m->bio->bi_end_io = m->saved_bi_end_io;
> > +		atomic_inc(&m->bio->bi_remaining);
> > +	}
> >  	cell_error(m->tc->pool, m->cell);
> >  	list_del(&m->list);
> >  	mempool_free(m, m->tc->pool->mapping_pool);
> > @@ -626,8 +628,10 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
> >  	int r;
> >  
> >  	bio = m->bio;
> > -	if (bio)
> > +	if (bio) {
> >  		bio->bi_end_io = m->saved_bi_end_io;
> > +		atomic_inc(&bio->bi_remaining);
> > +	}
> >  
> >  	if (m->err) {
> >  		cell_error(pool, m->cell);
> 
> But now that I look closer, the above dm-thin.c hunks belong in:
> [PATCH 19/23] block: Generic bio chaining
> 
> Seems these changes were mistakenly folded into this 17/23 patch?

...Whoops, fixed. Here's the new versions if you want to take a look:

http://evilpiepirate.org/git/linux-bcache.git/log/?h=for-jens
http://evilpiepirate.org/git/linux-bcache.git/commit/?h=for-jens&id=74f0f2084f88bb38403ca80bb98976f8219f9262

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Mike Snitzer Oct. 30, 2013, 12:29 a.m. UTC | #4
On Tue, Oct 29 2013 at  8:19pm -0400,
Kent Overstreet <kmo@daterainc.com> wrote:

> On Tue, Oct 29, 2013 at 08:09:08PM -0400, Mike Snitzer wrote:
> > 
> > But now that I look closer, the above dm-thin.c hunks belong in:
> > [PATCH 19/23] block: Generic bio chaining
> > 
> > Seems these changes were mistakenly folded into this 17/23 patch?
> 
> ...Whoops, fixed. Here's the new versions if you want to take a look:
> 
> http://evilpiepirate.org/git/linux-bcache.git/log/?h=for-jens
> http://evilpiepirate.org/git/linux-bcache.git/commit/?h=for-jens&id=74f0f2084f88bb38403ca80bb98976f8219f9262

Yeap, looks good (aside from the dm patches not having my Reviewed-by).

Not sure if Jens can add it?..  that said, I don't mind the commits not
having my Reviewed-by but it does lose some context for your changes
having had some other eyeballs on them.

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Jens Axboe Oct. 31, 2013, 2:05 p.m. UTC | #5
On Tue, Oct 29 2013, Mike Snitzer wrote:
> On Tue, Oct 29 2013 at  8:19pm -0400,
> Kent Overstreet <kmo@daterainc.com> wrote:
> 
> > On Tue, Oct 29, 2013 at 08:09:08PM -0400, Mike Snitzer wrote:
> > > 
> > > But now that I look closer, the above dm-thin.c hunks belong in:
> > > [PATCH 19/23] block: Generic bio chaining
> > > 
> > > Seems these changes were mistakenly folded into this 17/23 patch?
> > 
> > ...Whoops, fixed. Here's the new versions if you want to take a look:
> > 
> > http://evilpiepirate.org/git/linux-bcache.git/log/?h=for-jens
> > http://evilpiepirate.org/git/linux-bcache.git/commit/?h=for-jens&id=74f0f2084f88bb38403ca80bb98976f8219f9262
> 
> Yeap, looks good (aside from the dm patches not having my Reviewed-by).
> 
> Not sure if Jens can add it?..  that said, I don't mind the commits not
> having my Reviewed-by but it does lose some context for your changes
> having had some other eyeballs on them.

I have added it, thanks Mike.
diff mbox

Patch

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index a654024..1abb4a2 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -611,8 +611,10 @@  static void cell_defer_no_holder(struct thin_c *tc, struct dm_bio_prison_cell *c
 
 static void process_prepared_mapping_fail(struct dm_thin_new_mapping *m)
 {
-	if (m->bio)
+	if (m->bio) {
 		m->bio->bi_end_io = m->saved_bi_end_io;
+		atomic_inc(&m->bio->bi_remaining);
+	}
 	cell_error(m->tc->pool, m->cell);
 	list_del(&m->list);
 	mempool_free(m, m->tc->pool->mapping_pool);
@@ -626,8 +628,10 @@  static void process_prepared_mapping(struct dm_thin_new_mapping *m)
 	int r;
 
 	bio = m->bio;
-	if (bio)
+	if (bio) {
 		bio->bi_end_io = m->saved_bi_end_io;
+		atomic_inc(&bio->bi_remaining);
+	}
 
 	if (m->err) {
 		cell_error(pool, m->cell);
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index e749bc4..af20a84 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1119,7 +1119,6 @@  struct clone_info {
 	struct dm_io *io;
 	sector_t sector;
 	sector_t sector_count;
-	unsigned short idx;
 };
 
 static void bio_setup_sector(struct bio *bio, sector_t sector, sector_t len)
@@ -1128,68 +1127,24 @@  static void bio_setup_sector(struct bio *bio, sector_t sector, sector_t len)
 	bio->bi_iter.bi_size = to_bytes(len);
 }
 
-static void bio_setup_bv(struct bio *bio, unsigned short idx, unsigned short bv_count)
-{
-	bio->bi_iter.bi_idx = idx;
-	bio->bi_vcnt = idx + bv_count;
-	bio->bi_flags &= ~(1 << BIO_SEG_VALID);
-}
-
-static void clone_bio_integrity(struct bio *bio, struct bio *clone,
-				unsigned short idx, unsigned len, unsigned offset,
-				unsigned trim)
-{
-	if (!bio_integrity(bio))
-		return;
-
-	bio_integrity_clone(clone, bio, GFP_NOIO);
-
-	if (trim)
-		bio_integrity_trim(clone, bio_sector_offset(bio, idx, offset), len);
-}
-
-/*
- * Creates a little bio that just does part of a bvec.
- */
-static void clone_split_bio(struct dm_target_io *tio, struct bio *bio,
-			    sector_t sector, unsigned short idx,
-			    unsigned offset, unsigned len)
-{
-	struct bio *clone = &tio->clone;
-	struct bio_vec *bv = bio->bi_io_vec + idx;
-
-	*clone->bi_io_vec = *bv;
-
-	bio_setup_sector(clone, sector, len);
-
-	clone->bi_bdev = bio->bi_bdev;
-	clone->bi_rw = bio->bi_rw;
-	clone->bi_vcnt = 1;
-	clone->bi_io_vec->bv_offset = offset;
-	clone->bi_io_vec->bv_len = clone->bi_iter.bi_size;
-	clone->bi_flags |= 1 << BIO_CLONED;
-
-	clone_bio_integrity(bio, clone, idx, len, offset, 1);
-}
-
 /*
  * Creates a bio that consists of range of complete bvecs.
  */
 static void clone_bio(struct dm_target_io *tio, struct bio *bio,
-		      sector_t sector, unsigned short idx,
-		      unsigned short bv_count, unsigned len)
+		      sector_t sector, unsigned len)
 {
 	struct bio *clone = &tio->clone;
-	unsigned trim = 0;
 
 	__bio_clone(clone, bio);
-	bio_setup_sector(clone, sector, len);
-	bio_setup_bv(clone, idx, bv_count);
 
-	if (idx != bio->bi_iter.bi_idx ||
-	    clone->bi_iter.bi_size < bio->bi_iter.bi_size)
-		trim = 1;
-	clone_bio_integrity(bio, clone, idx, len, 0, trim);
+	if (bio_integrity(bio))
+		bio_integrity_clone(clone, bio, GFP_NOIO);
+
+	bio_advance(clone, to_bytes(sector - clone->bi_iter.bi_sector));
+	clone->bi_iter.bi_size = to_bytes(len);
+
+	if (bio_integrity(bio))
+		bio_integrity_trim(clone, 0, len);
 }
 
 static struct dm_target_io *alloc_tio(struct clone_info *ci,
@@ -1251,10 +1206,7 @@  static int __send_empty_flush(struct clone_info *ci)
 }
 
 static void __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti,
-				     sector_t sector, int nr_iovecs,
-				     unsigned short idx, unsigned short bv_count,
-				     unsigned offset, unsigned len,
-				     unsigned split_bvec)
+				     sector_t sector, unsigned len)
 {
 	struct bio *bio = ci->bio;
 	struct dm_target_io *tio;
@@ -1268,11 +1220,8 @@  static void __clone_and_map_data_bio(struct clone_info *ci, struct dm_target *ti
 		num_target_bios = ti->num_write_bios(ti, bio);
 
 	for (target_bio_nr = 0; target_bio_nr < num_target_bios; target_bio_nr++) {
-		tio = alloc_tio(ci, ti, nr_iovecs, target_bio_nr);
-		if (split_bvec)
-			clone_split_bio(tio, bio, sector, idx, offset, len);
-		else
-			clone_bio(tio, bio, sector, idx, bv_count, len);
+		tio = alloc_tio(ci, ti, bio_segments(bio), target_bio_nr);
+		clone_bio(tio, bio, sector, len);
 		__map_bio(tio);
 	}
 }
@@ -1344,68 +1293,13 @@  static int __send_write_same(struct clone_info *ci)
 }
 
 /*
- * Find maximum number of sectors / bvecs we can process with a single bio.
- */
-static sector_t __len_within_target(struct clone_info *ci, sector_t max, int *idx)
-{
-	struct bio *bio = ci->bio;
-	sector_t bv_len, total_len = 0;
-
-	for (*idx = ci->idx; max && (*idx < bio->bi_vcnt); (*idx)++) {
-		bv_len = to_sector(bio->bi_io_vec[*idx].bv_len);
-
-		if (bv_len > max)
-			break;
-
-		max -= bv_len;
-		total_len += bv_len;
-	}
-
-	return total_len;
-}
-
-static int __split_bvec_across_targets(struct clone_info *ci,
-				       struct dm_target *ti, sector_t max)
-{
-	struct bio *bio = ci->bio;
-	struct bio_vec *bv = bio->bi_io_vec + ci->idx;
-	sector_t remaining = to_sector(bv->bv_len);
-	unsigned offset = 0;
-	sector_t len;
-
-	do {
-		if (offset) {
-			ti = dm_table_find_target(ci->map, ci->sector);
-			if (!dm_target_is_valid(ti))
-				return -EIO;
-
-			max = max_io_len(ci->sector, ti);
-		}
-
-		len = min(remaining, max);
-
-		__clone_and_map_data_bio(ci, ti, ci->sector, 1, ci->idx, 0,
-					 bv->bv_offset + offset, len, 1);
-
-		ci->sector += len;
-		ci->sector_count -= len;
-		offset += to_bytes(len);
-	} while (remaining -= len);
-
-	ci->idx++;
-
-	return 0;
-}
-
-/*
  * Select the correct strategy for processing a non-flush bio.
  */
 static int __split_and_process_non_flush(struct clone_info *ci)
 {
 	struct bio *bio = ci->bio;
 	struct dm_target *ti;
-	sector_t len, max;
-	int idx;
+	unsigned len;
 
 	if (unlikely(bio->bi_rw & REQ_DISCARD))
 		return __send_discard(ci);
@@ -1416,41 +1310,14 @@  static int __split_and_process_non_flush(struct clone_info *ci)
 	if (!dm_target_is_valid(ti))
 		return -EIO;
 
-	max = max_io_len(ci->sector, ti);
-
-	/*
-	 * Optimise for the simple case where we can do all of
-	 * the remaining io with a single clone.
-	 */
-	if (ci->sector_count <= max) {
-		__clone_and_map_data_bio(ci, ti, ci->sector, bio->bi_max_vecs,
-					 ci->idx, bio->bi_vcnt - ci->idx, 0,
-					 ci->sector_count, 0);
-		ci->sector_count = 0;
-		return 0;
-	}
-
-	/*
-	 * There are some bvecs that don't span targets.
-	 * Do as many of these as possible.
-	 */
-	if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) {
-		len = __len_within_target(ci, max, &idx);
-
-		__clone_and_map_data_bio(ci, ti, ci->sector, bio->bi_max_vecs,
-					 ci->idx, idx - ci->idx, 0, len, 0);
+	len = min_t(sector_t, max_io_len(ci->sector, ti), ci->sector_count);
 
-		ci->sector += len;
-		ci->sector_count -= len;
-		ci->idx = idx;
+	__clone_and_map_data_bio(ci, ti, ci->sector, len);
 
-		return 0;
-	}
+	ci->sector += len;
+	ci->sector_count -= len;
 
-	/*
-	 * Handle a bvec that must be split between two or more targets.
-	 */
-	return __split_bvec_across_targets(ci, ti, max);
+	return 0;
 }
 
 /*
@@ -1476,7 +1343,6 @@  static void __split_and_process_bio(struct mapped_device *md,
 	ci.io->md = md;
 	spin_lock_init(&ci.io->endio_lock);
 	ci.sector = bio->bi_iter.bi_sector;
-	ci.idx = bio->bi_iter.bi_idx;
 
 	start_io_acct(ci.io);
 
diff --git a/fs/bio.c b/fs/bio.c
index ff5195d..54f44a1 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -1827,44 +1827,6 @@  void bio_trim(struct bio *bio, int offset, int size)
 }
 EXPORT_SYMBOL_GPL(bio_trim);
 
-/**
- *      bio_sector_offset - Find hardware sector offset in bio
- *      @bio:           bio to inspect
- *      @index:         bio_vec index
- *      @offset:        offset in bv_page
- *
- *      Return the number of hardware sectors between beginning of bio
- *      and an end point indicated by a bio_vec index and an offset
- *      within that vector's page.
- */
-sector_t bio_sector_offset(struct bio *bio, unsigned short index,
-			   unsigned int offset)
-{
-	unsigned int sector_sz;
-	struct bio_vec *bv;
-	sector_t sectors;
-	int i;
-
-	sector_sz = queue_logical_block_size(bio->bi_bdev->bd_disk->queue);
-	sectors = 0;
-
-	if (index >= bio->bi_iter.bi_idx)
-		index = bio->bi_vcnt - 1;
-
-	bio_for_each_segment_all(bv, bio, i) {
-		if (i == index) {
-			if (offset > bv->bv_offset)
-				sectors += (offset - bv->bv_offset) / sector_sz;
-			break;
-		}
-
-		sectors += bv->bv_len / sector_sz;
-	}
-
-	return sectors;
-}
-EXPORT_SYMBOL(bio_sector_offset);
-
 /*
  * create memory pools for biovec's in a bio_set.
  * use the global biovec slabs created for general use.
diff --git a/include/linux/bio.h b/include/linux/bio.h
index e1f6eda..6aaeeb1 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -368,7 +368,6 @@  extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned int);
 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
 			   unsigned int, unsigned int);
 extern int bio_get_nr_vecs(struct block_device *);
-extern sector_t bio_sector_offset(struct bio *, unsigned short, unsigned int);
 extern struct bio *bio_map_user(struct request_queue *, struct block_device *,
 				unsigned long, unsigned int, int, gfp_t);
 struct sg_iovec;