[PATCH 17/19] RDMA/rw: Expose maximal page list for a device per 1 MR

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ULP's will use this information to determine the maximal data transfer
size per IO operation.

Signed-off-by: Max Gurtovoy <maxg@xxxxxxxxxxxx>
---
 drivers/infiniband/core/rw.c | 14 ++++++++++++--
 include/rdma/rw.h            |  1 +
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/core/rw.c b/drivers/infiniband/core/rw.c
index 4fad732..edc9bee 100644
--- a/drivers/infiniband/core/rw.c
+++ b/drivers/infiniband/core/rw.c
@@ -56,8 +56,17 @@ static inline bool rdma_rw_io_needs_mr(struct ib_device *dev, u8 port_num,
 	return false;
 }
 
-static inline u32 rdma_rw_fr_page_list_len(struct ib_device *dev,
-					   bool pi_support)
+/**
+ * rdma_rw_fr_page_list_len - return the max number of pages mapped by 1 MR
+ * @dev:	RDMA device that will eventually create a PD for needed MRs
+ * @pi_support:	Whether MRs will be created for protection information offload
+ *
+ * Returns the number of pages that one MR can map for RDMA operation by the
+ * given device. One can determine the maximal data size according to the
+ * result of this function, or chose using multiple MRs for the RDMA operation
+ * as well.
+ */
+u32 rdma_rw_fr_page_list_len(struct ib_device *dev, bool pi_support)
 {
 	u32 max_pages;
 
@@ -69,6 +78,7 @@ static inline u32 rdma_rw_fr_page_list_len(struct ib_device *dev,
 	/* arbitrary limit to avoid allocating gigantic resources */
 	return min_t(u32, max_pages, 256);
 }
+EXPORT_SYMBOL(rdma_rw_fr_page_list_len);
 
 static inline int rdma_rw_inv_key(struct rdma_rw_reg_ctx *reg)
 {
diff --git a/include/rdma/rw.h b/include/rdma/rw.h
index 6ad9dc8..a9bbda7 100644
--- a/include/rdma/rw.h
+++ b/include/rdma/rw.h
@@ -69,5 +69,6 @@ unsigned int rdma_rw_mr_factor(struct ib_device *device, u8 port_num,
 void rdma_rw_init_qp(struct ib_device *dev, struct ib_qp_init_attr *attr);
 int rdma_rw_init_mrs(struct ib_qp *qp, struct ib_qp_init_attr *attr);
 void rdma_rw_cleanup_mrs(struct ib_qp *qp);
+u32 rdma_rw_fr_page_list_len(struct ib_device *dev, bool pi_support);
 
 #endif /* _RDMA_RW_H */
-- 
1.8.3.1




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