RDMA/core: add MR support for bvec-based RDMA operations

The bvec-based RDMA API currently returns -EOPNOTSUPP when Memory
Region registration is required. This prevents iWARP devices from
using the bvec path, since iWARP requires MR registration for RDMA
READ operations. The force_mr debug parameter is also unusable with
bvec input.

Add rdma_rw_init_mr_wrs_bvec() to handle MR registration for bvec
arrays. The approach creates a synthetic scatterlist populated with
DMA addresses from the bvecs, then reuses the existing ib_map_mr_sg()
infrastructure. This avoids driver changes while keeping the
implementation small.

The synthetic scatterlist is stored in the rdma_rw_ctx for cleanup.
On destroy, the MRs are returned to the pool and the bvec DMA
mappings are released using the stored addresses.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Link: https://patch.msgid.link/20260128005400.25147-4-cel@kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Leon Romanovsky <leon@kernel.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/rdma/rw.h b/include/rdma/rw.h
index 205e16ed6cd8..3400c017bfb6 100644
--- a/include/rdma/rw.h
+++ b/include/rdma/rw.h
@@ -47,6 +47,7 @@ struct rdma_rw_ctx {
 			struct ib_reg_wr	reg_wr;
 			struct ib_send_wr	inv_wr;
 			struct ib_mr		*mr;
+			struct sg_table		sgt;
 		} *reg;
 	};
 };