[PATCH V7 1/6] block: export bio_add_hw_pages()

[Chaitanya Kulkarni]

To implement the NVMe Zone Append command on the NVMeOF target side for
generic Zoned Block Devices with NVMe Zoned Namespaces interface, we
need to build the bios with hardware limitations, i.e. we use
bio_add_hw_page() with queue_max_zone_append_sectors() instead of
bio_add_page().

Without this API being exported NVMeOF target will require to use
bio_add_hw_page() caller bio_iov_iter_get_pages(). That results in
extra work which is inefficient.

Export the API so that NVMeOF ZBD over ZNS backend can use it to build
Zone Append bios.

Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni at wdc.com>
---
 block/bio.c            | 1 +
 block/blk.h            | 4 ----
 include/linux/blkdev.h | 4 ++++
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index fa01bef35bb1..eafd97c6c7fd 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -826,6 +826,7 @@ int bio_add_hw_page(struct request_queue *q, struct bio *bio,
 	bio->bi_iter.bi_size += len;
 	return len;
 }
+EXPORT_SYMBOL(bio_add_hw_page);
 
 /**
  * bio_add_pc_page	- attempt to add page to passthrough bio
diff --git a/block/blk.h b/block/blk.h
index e05507a8d1e3..1fdb8d5d8590 100644
--- a/block/blk.h
+++ b/block/blk.h
@@ -428,8 +428,4 @@ static inline void part_nr_sects_write(struct hd_struct *part, sector_t size)
 #endif
 }
 
-int bio_add_hw_page(struct request_queue *q, struct bio *bio,
-		struct page *page, unsigned int len, unsigned int offset,
-		unsigned int max_sectors, bool *same_page);
-
 #endif /* BLK_INTERNAL_H */
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 05b346a68c2e..2bdaa7cacfa3 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -2023,4 +2023,8 @@ int fsync_bdev(struct block_device *bdev);
 struct super_block *freeze_bdev(struct block_device *bdev);
 int thaw_bdev(struct block_device *bdev, struct super_block *sb);
 
+int bio_add_hw_page(struct request_queue *q, struct bio *bio,
+		struct page *page, unsigned int len, unsigned int offset,
+		unsigned int max_sectors, bool *same_page);
+
 #endif /* _LINUX_BLKDEV_H */
-- 
2.22.1