[PATCH 02/15] block: blk-integiry: add helper functions for bio_integrity_add_page

[Jinyoung CHOI]

Add functions that use the hardware limit to merge the page with
integrity's bio_vec.
Using the added functions, the physically continuous pages are made of
one bio_vec.

Previously, physically continuous pages were not created as one
bio_vec, but separately created.

Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Martin K. Petersen <martin.petersen@xxxxxxxxxx>

Signed-off-by: Jinyoung Choi <j-young.choi@xxxxxxxxxxx>
---
 block/bio-integrity.c | 58 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/block/bio-integrity.c b/block/bio-integrity.c
index 4533eb491661..06b6a2c178d2 100644
--- a/block/bio-integrity.c
+++ b/block/bio-integrity.c
@@ -111,6 +111,64 @@ void bio_integrity_free(struct bio *bio)
 	bio->bi_opf &= ~REQ_INTEGRITY;
 }
 
+/**
+ * bip_full - check if the bip is full
+ * @bip:	bip to check
+ * @len:	length of one segment to be added
+ *
+ * Return true if @bip is full and one segment with @len bytes can't be
+ * added to the bip, otherwise return false
+ */
+static inline bool bip_full(struct bio_integrity_payload *bip, unsigned int len)
+{
+	if (bip->bip_vcnt >= bip->bip_max_vcnt)
+		return true;
+	if (bip->bip_iter.bi_size > UINT_MAX - len)
+		return true;
+	return false;
+}
+
+/**
+ * bip_try_merge_hw_seg - try to merge a page into a segment, while
+ * obeying the hardware segment size limit
+ * @q:		the target queue
+ * @bip:	bip to check
+ * @page:	page containing integrity metadata
+ * @len:	number of bytes of integrity metadata in page
+ * @offset:	start offset within page
+ * @same_page:  return if the segment has been merged inside the same page
+ *
+ * Return true if @page is merged to @bip, otherwise return false
+ */
+static bool bip_try_merge_hw_seg(struct request_queue *q,
+				 struct bio_integrity_payload *bip,
+				 struct page *page, unsigned int len,
+				 unsigned int offset, bool *same_page)
+{
+	struct bio_vec *bv = &bip->bip_vec[bip->bip_vcnt - 1];
+	unsigned long mask = queue_segment_boundary(q);
+	phys_addr_t addr1 = page_to_phys(bv->bv_page) + bv->bv_offset;
+	phys_addr_t addr2 = page_to_phys(page) + offset + len - 1;
+
+	if ((addr1 | mask) != (addr2 | mask))
+		return false;
+	if (bv->bv_len + len > queue_max_segment_size(q))
+		return false;
+
+	if (bip->bip_vcnt > 0) {
+		if (bio_page_is_mergeable(bv, page, len, offset, same_page)) {
+			if (bip->bip_iter.bi_size > UINT_MAX - len) {
+				*same_page = false;
+				return false;
+			}
+			bv->bv_len += len;
+			bip->bip_iter.bi_size += len;
+			return true;
+		}
+	}
+	return false;
+}
+
 /**
  * bio_integrity_add_page - Attach integrity metadata
  * @bio:	bio to update
-- 
2.34.1