[dm-devel] [PATCH 03/22] bcache: Kill unaligned bvec hack

[Kent Overstreet]

Bcache has a hack to avoid cloning the biovec if it's all full pages -
but with immutable biovecs coming this won't be necessary anymore.

For now, we remove the special case and always clone the bvec array so
that the immutable biovec patches are simpler.

Signed-off-by: Kent Overstreet <kmo at daterainc.com>
---
 drivers/md/bcache/bcache.h  |  1 -
 drivers/md/bcache/debug.c   |  4 ----
 drivers/md/bcache/request.c | 32 +++++---------------------------
 drivers/md/bcache/request.h |  2 +-
 drivers/md/bcache/super.c   |  4 ----
 5 files changed, 6 insertions(+), 37 deletions(-)

diff --git a/drivers/md/bcache/bcache.h b/drivers/md/bcache/bcache.h
index b39f6f0..ec5f17c 100644
--- a/drivers/md/bcache/bcache.h
+++ b/drivers/md/bcache/bcache.h
@@ -443,7 +443,6 @@ struct bcache_device {
 	unsigned long		sectors_dirty_last;
 	long			sectors_dirty_derivative;
 
-	mempool_t		*unaligned_bvec;
 	struct bio_set		*bio_split;
 
 	unsigned		data_csum:1;
diff --git a/drivers/md/bcache/debug.c b/drivers/md/bcache/debug.c
index 88e6411..545680b 100644
--- a/drivers/md/bcache/debug.c
+++ b/drivers/md/bcache/debug.c
@@ -191,10 +191,6 @@ void bch_data_verify(struct search *s)
 	struct bio_vec *bv;
 	int i;
 
-	if (!s->unaligned_bvec)
-		bio_for_each_segment(bv, s->orig_bio, i)
-			bv->bv_offset = 0, bv->bv_len = PAGE_SIZE;
-
 	check = bio_clone(s->orig_bio, GFP_NOIO);
 	if (!check)
 		return;
diff --git a/drivers/md/bcache/request.c b/drivers/md/bcache/request.c
index 786a1a4..2c2e1c1 100644
--- a/drivers/md/bcache/request.c
+++ b/drivers/md/bcache/request.c
@@ -679,10 +679,14 @@ static void bio_complete(struct search *s)
 static void do_bio_hook(struct search *s)
 {
 	struct bio *bio = &s->bio.bio;
-	memcpy(bio, s->orig_bio, sizeof(struct bio));
 
+	bio_init(bio);
+	bio->bi_io_vec		= s->bv;
+	bio->bi_max_vecs	= BIO_MAX_PAGES;
+	__bio_clone(bio, s->orig_bio);
 	bio->bi_end_io		= request_endio;
 	bio->bi_private		= &s->cl;
+
 	atomic_set(&bio->bi_cnt, 3);
 }
 
@@ -694,16 +698,12 @@ static void search_free(struct closure *cl)
 	if (s->op.cache_bio)
 		bio_put(s->op.cache_bio);
 
-	if (s->unaligned_bvec)
-		mempool_free(s->bio.bio.bi_io_vec, s->d->unaligned_bvec);
-
 	closure_debug_destroy(cl);
 	mempool_free(s, s->d->c->search);
 }
 
 static struct search *search_alloc(struct bio *bio, struct bcache_device *d)
 {
-	struct bio_vec *bv;
 	struct search *s = mempool_alloc(d->c->search, GFP_NOIO);
 	memset(s, 0, offsetof(struct search, op.keys));
 
@@ -722,15 +722,6 @@ static struct search *search_alloc(struct bio *bio, struct bcache_device *d)
 	s->start_time		= jiffies;
 	do_bio_hook(s);
 
-	if (bio->bi_size != bio_segments(bio) * PAGE_SIZE) {
-		bv = mempool_alloc(d->unaligned_bvec, GFP_NOIO);
-		memcpy(bv, bio_iovec(bio),
-		       sizeof(struct bio_vec) * bio_segments(bio));
-
-		s->bio.bio.bi_io_vec	= bv;
-		s->unaligned_bvec	= 1;
-	}
-
 	return s;
 }
 
@@ -780,26 +771,13 @@ static void cached_dev_read_complete(struct closure *cl)
 static void request_read_error(struct closure *cl)
 {
 	struct search *s = container_of(cl, struct search, cl);
-	struct bio_vec *bv;
-	int i;
 
 	if (s->recoverable) {
 		/* Retry from the backing device: */
 		trace_bcache_read_retry(s->orig_bio);
 
 		s->error = 0;
-		bv = s->bio.bio.bi_io_vec;
 		do_bio_hook(s);
-		s->bio.bio.bi_io_vec = bv;
-
-		if (!s->unaligned_bvec)
-			bio_for_each_segment(bv, s->orig_bio, i)
-				bv->bv_offset = 0, bv->bv_len = PAGE_SIZE;
-		else
-			memcpy(s->bio.bio.bi_io_vec,
-			       bio_iovec(s->orig_bio),
-			       sizeof(struct bio_vec) *
-			       bio_segments(s->orig_bio));
 
 		/* XXX: invalidate cache */
 
diff --git a/drivers/md/bcache/request.h b/drivers/md/bcache/request.h
index 57dc478..bee95a9 100644
--- a/drivers/md/bcache/request.h
+++ b/drivers/md/bcache/request.h
@@ -16,7 +16,6 @@ struct search {
 	unsigned		cache_bio_sectors;
 
 	unsigned		recoverable:1;
-	unsigned		unaligned_bvec:1;
 
 	unsigned		write:1;
 	unsigned		writeback:1;
@@ -27,6 +26,7 @@ struct search {
 
 	/* Anything past op->keys won't get zeroed in do_bio_hook */
 	struct btree_op		op;
+	struct bio_vec		bv[BIO_MAX_PAGES];
 };
 
 void bch_cache_read_endio(struct bio *, int);
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 547c4c5..dc073eb 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -743,8 +743,6 @@ static void bcache_device_free(struct bcache_device *d)
 		put_disk(d->disk);
 
 	bio_split_pool_free(&d->bio_split_hook);
-	if (d->unaligned_bvec)
-		mempool_destroy(d->unaligned_bvec);
 	if (d->bio_split)
 		bioset_free(d->bio_split);
 	if (is_vmalloc_addr(d->stripe_sectors_dirty))
@@ -778,8 +776,6 @@ static int bcache_device_init(struct bcache_device *d, unsigned block_size,
 		return -ENOMEM;
 
 	if (!(d->bio_split = bioset_create(4, offsetof(struct bbio, bio))) ||
-	    !(d->unaligned_bvec = mempool_create_kmalloc_pool(1,
-				sizeof(struct bio_vec) * BIO_MAX_PAGES)) ||
 	    bio_split_pool_init(&d->bio_split_hook) ||
 	    !(d->disk = alloc_disk(1)) ||
 	    !(q = blk_alloc_queue(GFP_KERNEL)))
-- 
1.8.4.rc1