bcache: Kill unaligned bvec hack

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 <[e-mail]>

drivers/md/bcache/bcache.h

···
 	unsigned long		sectors_dirty_last;
 	long			sectors_dirty_derivative;
 
-	mempool_t		*unaligned_bvec;
 	struct bio_set		*bio_split;
 
 	unsigned		data_csum:1;

drivers/md/bcache/request.c

···
 	unsigned		insert_bio_sectors;
 
 	unsigned		recoverable:1;
-	unsigned		unaligned_bvec:1;
 	unsigned		write:1;
 	unsigned		read_dirty_data:1;
 
···
 
 	struct btree_op		op;
 	struct data_insert_op	iop;
+	struct bio_vec		bv[BIO_MAX_PAGES];
 };
 
 static void bch_cache_read_endio(struct bio *bio, int error)
···
 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);
 }
 
···
 	if (s->iop.bio)
 		bio_put(s->iop.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 search *s;
-	struct bio_vec *bv;
 
 	s = mempool_alloc(d->c->search, GFP_NOIO);
 	memset(s, 0, offsetof(struct search, iop.insert_keys));
···
 	s->recoverable		= 1;
 	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;
 }
···
 {
 	struct search *s = container_of(cl, struct search, cl);
 	struct bio *bio = &s->bio.bio;
-	struct bio_vec *bv;
-	int i;
 
 	if (s->recoverable) {
 		/* Retry from the backing device: */
 		trace_bcache_read_retry(s->orig_bio);
 
 		s->iop.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 */
 
···
 		s->cache_miss = NULL;
 	}
 
-	if (verify(dc, &s->bio.bio) && s->recoverable &&
-	    !s->unaligned_bvec && !s->read_dirty_data)
+	if (verify(dc, &s->bio.bio) && s->recoverable && !s->read_dirty_data)
 		bch_data_verify(dc, s->orig_bio);
 
 	bio_complete(s);

drivers/md/bcache/super.c

···
 	}
 
 	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->full_dirty_stripes))
···
 		return minor;
 
 	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))) {
 		ida_simple_remove(&bcache_minor, minor);