[PATCH 01/19] block: export bio_split_rw

[Christoph Hellwig <hch@lst.de>]

bio_split_rw can be used by file systems to split and incoming write
bio into multiple bios fitting the hardware limit for use as ZONE_APPEND
bios.  Export it for initial use in btrfs.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 block/blk-merge.c   | 3 ++-
 include/linux/bio.h | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/block/blk-merge.c b/block/blk-merge.c
index ff04e9290715a..e68295462977b 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -267,7 +267,7 @@ static bool bvec_split_segs(struct queue_limits *lim, const struct bio_vec *bv,
  * responsible for ensuring that @bs is only destroyed after processing of the
  * split bio has finished.
  */
-static struct bio *bio_split_rw(struct bio *bio, struct queue_limits *lim,
+struct bio *bio_split_rw(struct bio *bio, struct queue_limits *lim,
 		unsigned *segs, struct bio_set *bs, unsigned max_bytes)
 {
 	struct bio_vec bv, bvprv, *bvprvp = NULL;
@@ -317,6 +317,7 @@ static struct bio *bio_split_rw(struct bio *bio, struct queue_limits *lim,
 	bio_clear_polled(bio);
 	return bio_split(bio, bytes >> SECTOR_SHIFT, GFP_NOIO, bs);
 }
+EXPORT_SYMBOL_GPL(bio_split_rw);
 
 /**
  * __bio_split_to_limits - split a bio to fit the queue limits
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 2c5806997bbf7..730afea66cc89 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -12,6 +12,8 @@
 
 #define BIO_MAX_VECS		256U
 
+struct queue_limits;
+
 static inline unsigned int bio_max_segs(unsigned int nr_segs)
 {
 	return min(nr_segs, BIO_MAX_VECS);
@@ -375,6 +377,8 @@ static inline void bip_set_seed(struct bio_integrity_payload *bip,
 void bio_trim(struct bio *bio, sector_t offset, sector_t size);
 extern struct bio *bio_split(struct bio *bio, int sectors,
 			     gfp_t gfp, struct bio_set *bs);
+struct bio *bio_split_rw(struct bio *bio, struct queue_limits *lim,
+		unsigned *segs, struct bio_set *bs, unsigned max_bytes);
 
 /**
  * bio_next_split - get next @sectors from a bio, splitting if necessary
-- 
2.30.2