[PATCH 08/12] block: add bio number of vecs helper for partials

[Keith Busch]

From: Keith Busch <kbusch at kernel.org>

Bit buckets get their own vector, so need to allocate enough to hold
both the preregistered bvecs and the bit buckets.

Signed-off-by: Keith Busch <kbusch at kernel.org>
---
 include/linux/bio.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/include/linux/bio.h b/include/linux/bio.h
index 992ee987f273..ded38accf009 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -452,6 +452,17 @@ static inline int bio_iov_vecs_to_alloc(struct iov_iter *iter, int max_segs)
 	return iov_iter_npages(iter, max_segs);
 }
 
+static inline int bio_iov_vecs_to_alloc_partial(struct iov_iter *iter,
+						int max_segs, bool trunc,
+						bool skip)
+{
+	if (skip || trunc)
+		return min(iov_iter_npages(iter, max_segs) + skip + trunc,
+			   max_segs);
+	else
+		return bio_iov_vecs_to_alloc(iter, max_segs);
+}
+
 struct request_queue;
 
 extern int submit_bio_wait(struct bio *bio);
-- 
2.30.2