[PATCH V15 1/5] block: export blk_next_bio()

[Chaitanya Kulkarni]

The block layer provides emulation of zone management operations
targeting all zones of a zoned block device only for the zone reset
operation (REQ_OP_ZONE_RESET). In order to correctly implement
exporting of zoned block devices with NVMeOF, emulating zone management
operations targeting all zones of a device is also necessary for the
open, close and finish zone operations (REQ_OP_ZONE_OPEN,
REQ_OP_ZONE_CLOSE and REQ_OP_ZONE_FINISH).

Instead of duplicating the code, export the existing helper from block
layer so we can use a bio chaining pattern that is present in the block
layer for REQ_OP_ZONE RESET all emulation in the NVMeOF zoned block
device backend.

Reviewed-by: Damien Le Moal <damien.lemoal at wdc.com>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
---
 block/blk-lib.c     | 1 +
 include/linux/bio.h | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/block/blk-lib.c b/block/blk-lib.c
index 7b256131b20b..9f09beadcbe3 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -21,6 +21,7 @@ struct bio *blk_next_bio(struct bio *bio, unsigned int nr_pages, gfp_t gfp)
 
 	return new;
 }
+EXPORT_SYMBOL_GPL(blk_next_bio);
 
 int __blkdev_issue_discard(struct block_device *bdev, sector_t sector,
 		sector_t nr_sects, gfp_t gfp_mask, int flags,
diff --git a/include/linux/bio.h b/include/linux/bio.h
index a0b4cfdf62a4..b2491ead22a0 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -822,4 +822,6 @@ static inline void bio_set_polled(struct bio *bio, struct kiocb *kiocb)
 		bio->bi_opf |= REQ_NOWAIT;
 }
 
+struct bio *blk_next_bio(struct bio *bio, unsigned int nr_pages, gfp_t gfp);
+
 #endif /* __LINUX_BIO_H */
-- 
2.22.1