From: Johannes Thumshirn <johannes.thumsh...@wdc.com>

Add bio_add_zone_append_page(), a wrapper around bio_add_hw_page() which
is intended to be used by file systems that directly add pages to a bio
instead of using bio_iov_iter_get_pages().

Cc: Jens Axboe <ax...@kernel.dk>
Reviewed-by: Christoph Hellwig <h...@lst.de>
Reviewed-by: Josef Bacik <jo...@toxicpanda.com>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulka...@wdc.com>
Signed-off-by: Johannes Thumshirn <johannes.thumsh...@wdc.com>
---
 block/bio.c         | 33 +++++++++++++++++++++++++++++++++
 include/linux/bio.h |  2 ++
 2 files changed, 35 insertions(+)

diff --git a/block/bio.c b/block/bio.c
index 1f2cc1fbe283..2f21d2958b60 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -851,6 +851,39 @@ int bio_add_pc_page(struct request_queue *q, struct bio 
*bio,
 }
 EXPORT_SYMBOL(bio_add_pc_page);
 
+/**
+ * bio_add_zone_append_page - attempt to add page to zone-append bio
+ * @bio: destination bio
+ * @page: page to add
+ * @len: vec entry length
+ * @offset: vec entry offset
+ *
+ * Attempt to add a page to the bio_vec maplist of a bio that will be submitted
+ * for a zone-append request. This can fail for a number of reasons, such as 
the
+ * bio being full or the target block device is not a zoned block device or
+ * other limitations of the target block device. The target block device must
+ * allow bio's up to PAGE_SIZE, so it is always possible to add a single page
+ * to an empty bio.
+ *
+ * Returns: number of bytes added to the bio, or 0 in case of a failure.
+ */
+int bio_add_zone_append_page(struct bio *bio, struct page *page,
+                            unsigned int len, unsigned int offset)
+{
+       struct request_queue *q = bio->bi_disk->queue;
+       bool same_page = false;
+
+       if (WARN_ON_ONCE(bio_op(bio) != REQ_OP_ZONE_APPEND))
+               return 0;
+
+       if (WARN_ON_ONCE(!blk_queue_is_zoned(q)))
+               return 0;
+
+       return bio_add_hw_page(q, bio, page, len, offset,
+                              queue_max_zone_append_sectors(q), &same_page);
+}
+EXPORT_SYMBOL_GPL(bio_add_zone_append_page);
+
 /**
  * __bio_try_merge_page - try appending data to an existing bvec.
  * @bio: destination bio
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 1edda614f7ce..de62911473bb 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -455,6 +455,8 @@ void bio_chain(struct bio *, struct bio *);
 extern int bio_add_page(struct bio *, struct page *, unsigned int,unsigned 
int);
 extern int bio_add_pc_page(struct request_queue *, struct bio *, struct page *,
                           unsigned int, unsigned int);
+int bio_add_zone_append_page(struct bio *bio, struct page *page,
+                            unsigned int len, unsigned int offset);
 bool __bio_try_merge_page(struct bio *bio, struct page *page,
                unsigned int len, unsigned int off, bool *same_page);
 void __bio_add_page(struct bio *bio, struct page *page,
-- 
2.27.0

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