block: export bio_free_pages to other modules

bio_free_pages is introduced in commit 1dfa0f68c0
("block: add a helper to free bio bounce buffer pages"),
we can reuse the func in other modules after it was
imported.

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@fb.com>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Shaohua Li <shli@fb.com>
Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
Acked-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

block/bio.c

@@ -1068,7 +1068,7 @@ static int bio_copy_to_iter(struct bio *bio, struct iov_iter iter)
 	return 0;
 }
 
-static void bio_free_pages(struct bio *bio)
+void bio_free_pages(struct bio *bio)
 {
 	struct bio_vec *bvec;
 	int i;
@@ -1076,6 +1076,7 @@ static void bio_free_pages(struct bio *bio)
 	bio_for_each_segment_all(bvec, bio, i)
 		__free_page(bvec->bv_page);
 }
+EXPORT_SYMBOL(bio_free_pages);
 
 /**
  *	bio_uncopy_user	-	finish previously mapped bio

drivers/md/bcache/btree.c

@@ -361,12 +361,8 @@ static void __btree_node_write_done(struct closure *cl)
 static void btree_node_write_done(struct closure *cl)
 {
 	struct btree *b = container_of(cl, struct btree, io);
-	struct bio_vec *bv;
-	int n;
-
-	bio_for_each_segment_all(bv, b->bio, n)
-		__free_page(bv->bv_page);
 
+	bio_free_pages(b->bio);
 	__btree_node_write_done(cl);
 }
 

drivers/md/bcache/debug.c

@@ -107,9 +107,8 @@ void bch_data_verify(struct cached_dev *dc, struct bio *bio)
 {
 	char name[BDEVNAME_SIZE];
 	struct bio *check;
-	struct bio_vec bv, *bv2;
+	struct bio_vec bv;
 	struct bvec_iter iter;
-	int i;
 
 	check = bio_clone(bio, GFP_NOIO);
 	if (!check)
@@ -136,8 +135,7 @@ void bch_data_verify(struct cached_dev *dc, struct bio *bio)
 		kunmap_atomic(p1);
 	}
 
-	bio_for_each_segment_all(bv2, check, i)
-		__free_page(bv2->bv_page);
+	bio_free_pages(check);
 out_put:
 	bio_put(check);
 }

drivers/md/bcache/movinggc.c

@@ -44,11 +44,8 @@ static void write_moving_finish(struct closure *cl)
 {
 	struct moving_io *io = container_of(cl, struct moving_io, cl);
 	struct bio *bio = &io->bio.bio;
-	struct bio_vec *bv;
-	int i;
 
-	bio_for_each_segment_all(bv, bio, i)
-		__free_page(bv->bv_page);
+	bio_free_pages(bio);
 
 	if (io->op.replace_collision)
 		trace_bcache_gc_copy_collision(&io->w->key);

drivers/md/bcache/request.c

@@ -694,13 +694,8 @@ static void cached_dev_cache_miss_done(struct closure *cl)
 	if (s->iop.replace_collision)
 		bch_mark_cache_miss_collision(s->iop.c, s->d);
 
-	if (s->iop.bio) {
-		int i;
-		struct bio_vec *bv;
-
-		bio_for_each_segment_all(bv, s->iop.bio, i)
-			__free_page(bv->bv_page);
-	}
+	if (s->iop.bio)
+		bio_free_pages(s->iop.bio);
 
 	cached_dev_bio_complete(cl);
 }

drivers/md/bcache/writeback.c

@@ -128,11 +128,8 @@ static void write_dirty_finish(struct closure *cl)
 	struct dirty_io *io = container_of(cl, struct dirty_io, cl);
 	struct keybuf_key *w = io->bio.bi_private;
 	struct cached_dev *dc = io->dc;
-	struct bio_vec *bv;
-	int i;
 
-	bio_for_each_segment_all(bv, &io->bio, i)
-		__free_page(bv->bv_page);
+	bio_free_pages(&io->bio);
 
 	/* This is kind of a dumb way of signalling errors. */
 	if (KEY_DIRTY(&w->key)) {

drivers/md/dm-log-writes.c

@@ -149,8 +149,6 @@ static void put_io_block(struct log_writes_c *lc)
 static void log_end_io(struct bio *bio)
 {
 	struct log_writes_c *lc = bio->bi_private;
-	struct bio_vec *bvec;
-	int i;
 
 	if (bio->bi_error) {
 		unsigned long flags;
@@ -161,9 +159,7 @@ static void log_end_io(struct bio *bio)
 		spin_unlock_irqrestore(&lc->blocks_lock, flags);
 	}
 
-	bio_for_each_segment_all(bvec, bio, i)
-		__free_page(bvec->bv_page);
-
+	bio_free_pages(bio);
 	put_io_block(lc);
 	bio_put(bio);
 }

drivers/md/raid1.c

@@ -145,12 +145,8 @@ static void * r1buf_pool_alloc(gfp_t gfp_flags, void *data)
 	return r1_bio;
 
 out_free_pages:
-	while (--j >= 0) {
-		struct bio_vec *bv;
-
-		bio_for_each_segment_all(bv, r1_bio->bios[j], i)
-			__free_page(bv->bv_page);
-	}
+	while (--j >= 0)
+		bio_free_pages(r1_bio->bios[j]);
 
 out_free_bio:
 	while (++j < pi->raid_disks)

include/linux/bio.h

@@ -459,6 +459,7 @@ static inline void bio_flush_dcache_pages(struct bio *bi)
 
 extern void bio_copy_data(struct bio *dst, struct bio *src);
 extern int bio_alloc_pages(struct bio *bio, gfp_t gfp);
+extern void bio_free_pages(struct bio *bio);
 
 extern struct bio *bio_copy_user_iov(struct request_queue *,
 				     struct rq_map_data *,