[PATCH for-next 08/17] RDMA/rxe: Add routine to compute number of frags for dma

[Bob Pearson <rpearsonhpe@xxxxxxxxx>]

Add routine named rxe_num_dma_frags() to compute the number of skb
frags needed to copy length bytes from a dma info struct.

Signed-off-by: Bob Pearson <rpearsonhpe@xxxxxxxxx>
---
 drivers/infiniband/sw/rxe/rxe_loc.h |  4 +-
 drivers/infiniband/sw/rxe/rxe_mr.c  | 67 ++++++++++++++++++++++++++++-
 2 files changed, 69 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h
index c62fc2613a01..4c30ffaccc92 100644
--- a/drivers/infiniband/sw/rxe/rxe_loc.h
+++ b/drivers/infiniband/sw/rxe/rxe_loc.h
@@ -76,10 +76,12 @@ int rxe_copy_mr_data(struct sk_buff *skb, struct rxe_mr *mr, u64 iova,
 		     enum rxe_mr_copy_op op);
 int rxe_mr_copy(struct rxe_mr *mr, u64 iova, void *addr, int length,
 		enum rxe_mr_copy_op op);
+int rxe_num_dma_frags(const struct rxe_pd *pd, const struct rxe_dma_info *dma,
+		      int length);
 int copy_data(struct rxe_pd *pd, int access, struct rxe_dma_info *dma,
 	      void *addr, int length, enum rxe_mr_copy_op op);
 void *iova_to_vaddr(struct rxe_mr *mr, u64 iova, int length);
-struct rxe_mr *lookup_mr(struct rxe_pd *pd, int access, u32 key,
+struct rxe_mr *lookup_mr(const struct rxe_pd *pd, int access, u32 key,
 			 enum rxe_mr_lookup_type type);
 int mr_check_range(struct rxe_mr *mr, u64 iova, size_t length);
 int advance_dma_data(struct rxe_dma_info *dma, unsigned int length);
diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
index fd39b3e17f41..77437a0dd7ec 100644
--- a/drivers/infiniband/sw/rxe/rxe_mr.c
+++ b/drivers/infiniband/sw/rxe/rxe_mr.c
@@ -522,6 +522,71 @@ int rxe_copy_mr_data(struct sk_buff *skb, struct rxe_mr *mr, u64 iova,
 	return 0;
 }
 
+/**
+ * rxe_num_dma_frags() - Count the number of skb frags needed to copy
+ *			 length bytes from a dma info struct to an skb
+ * @pd: protection domain used by dma entries
+ * @dma: dma info
+ * @length: number of bytes to copy
+ *
+ * Returns: number of frags needed or negative error
+ */
+int rxe_num_dma_frags(const struct rxe_pd *pd, const struct rxe_dma_info *dma,
+		      int length)
+{
+	int cur_sge = dma->cur_sge;
+	const struct rxe_sge *sge = &dma->sge[cur_sge];
+	int buf_offset = dma->sge_offset;
+	int resid = dma->resid;
+	struct rxe_mr *mr = NULL;
+	int bytes;
+	u64 iova;
+	int ret;
+	int num_frags = 0;
+
+	if (length == 0)
+		return 0;
+
+	if (length > resid)
+		return -EINVAL;
+
+	while (length > 0) {
+		if (buf_offset >= sge->length) {
+			if (mr)
+				rxe_put(mr);
+
+			sge++;
+			cur_sge++;
+			buf_offset = 0;
+
+			if (cur_sge >= dma->num_sge)
+				return -ENOSPC;
+			if (!sge->length)
+				continue;
+		}
+
+		mr = lookup_mr(pd, 0, sge->lkey, RXE_LOOKUP_LOCAL);
+		if (!mr)
+			return -EINVAL;
+
+		bytes = min_t(int, length, sge->length - buf_offset);
+		if (bytes > 0) {
+			iova = sge->addr + buf_offset;
+			ret = rxe_num_mr_frags(mr, iova, length);
+			if (ret < 0) {
+				rxe_put(mr);
+				return ret;
+			}
+
+			buf_offset += bytes;
+			resid -= bytes;
+			length -= bytes;
+		}
+	}
+
+	return num_frags;
+}
+
 /* copy data in or out of a wqe, i.e. sg list
  * under the control of a dma descriptor
  */
@@ -658,7 +723,7 @@ int advance_dma_data(struct rxe_dma_info *dma, unsigned int length)
  * (3) verify that the mr can support the requested access
  * (4) verify that mr state is valid
  */
-struct rxe_mr *lookup_mr(struct rxe_pd *pd, int access, u32 key,
+struct rxe_mr *lookup_mr(const struct rxe_pd *pd, int access, u32 key,
 			 enum rxe_mr_lookup_type type)
 {
 	struct rxe_mr *mr;
-- 
2.34.1