[PATCH 01/19] block: add a bio_add_virt_nofail helper

Add a helper to add a directly mapped kernel virtual address to a
bio so that callers don't have to convert to pages or folios.

For now only the _nofail variant is provided as that is what all the
obvious callers want.

Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Damien Le Moal <[email protected]>
Reviewed-by: Hannes Reinecke <[email protected]>
Reviewed-by: Johannes Thumshirn <[email protected]>
---
 block/bio.c         | 16 ++++++++++++++++
 include/linux/bio.h |  2 ++
 2 files changed, 18 insertions(+)

diff --git a/block/bio.c b/block/bio.c
index 1e42aefc7377..bd3d048d0a72 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -991,6 +991,22 @@ void __bio_add_page(struct bio *bio, struct page *page,
 }
 EXPORT_SYMBOL_GPL(__bio_add_page);
 
+/**
+ * bio_add_virt_nofail - add data in the direct kernel mapping to a bio
+ * @bio: destination bio
+ * @vaddr: data to add
+ * @len: length of the data to add, may cross pages
+ *
+ * Add the data at @vaddr to @bio.  The caller must have ensure a segment
+ * is available for the added data.  No merging into an existing segment
+ * will be performed.
+ */
+void bio_add_virt_nofail(struct bio *bio, void *vaddr, unsigned len)
+{
+	__bio_add_page(bio, virt_to_page(vaddr), len, offset_in_page(vaddr));
+}
+EXPORT_SYMBOL_GPL(bio_add_virt_nofail);
+
 /**
  *	bio_add_page	-	attempt to add page(s) to bio
  *	@bio: destination bio
diff --git a/include/linux/bio.h b/include/linux/bio.h
index cafc7c215de8..acca7464080c 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -417,6 +417,8 @@ void __bio_add_page(struct bio *bio, struct page *page,
 		unsigned int len, unsigned int off);
 void bio_add_folio_nofail(struct bio *bio, struct folio *folio, size_t len,
 			  size_t off);
+void bio_add_virt_nofail(struct bio *bio, void *vaddr, unsigned len);
+
 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
 void bio_iov_bvec_set(struct bio *bio, const struct iov_iter *iter);
 void __bio_release_pages(struct bio *bio, bool mark_dirty);
-- 
2.47.2