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Subject: [PATCH v2 1/6] xprtrdma: Remove FMR support in rpcrdma_convert_iovs()
From:   Chuck Lever <chuck.lever@oracle.com>
To:     linux-nfs@vger.kernel.org, linux-rdma@vger.kernel.org
Date:   Wed, 03 Feb 2021 11:23:54 -0500
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Support for FMR was removed by commit ba69cd122ece ("xprtrdma:
Remove support for FMR memory registration") [Dec 2018]. That means
the buffer-splitting behavior of rpcrdma_convert_kvec(), added by
commit 821c791a0bde ("xprtrdma: Segment head and tail XDR buffers
on page boundaries") [Mar 2016], is no longer necessary. FRWR
memory registration handles this case with aplomb.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
---
 net/sunrpc/xprtrdma/rpc_rdma.c |   19 ++++---------------
 1 file changed, 4 insertions(+), 15 deletions(-)

diff --git a/net/sunrpc/xprtrdma/rpc_rdma.c b/net/sunrpc/xprtrdma/rpc_rdma.c
index 8f5d0cb68360..832765f3ebba 100644
--- a/net/sunrpc/xprtrdma/rpc_rdma.c
+++ b/net/sunrpc/xprtrdma/rpc_rdma.c
@@ -204,9 +204,7 @@ rpcrdma_alloc_sparse_pages(struct xdr_buf *buf)
 	return 0;
 }
 
-/* Split @vec on page boundaries into SGEs. FMR registers pages, not
- * a byte range. Other modes coalesce these SGEs into a single MR
- * when they can.
+/* Convert @vec to a single SGL element.
  *
  * Returns pointer to next available SGE, and bumps the total number
  * of SGEs consumed.
@@ -215,21 +213,12 @@ static struct rpcrdma_mr_seg *
 rpcrdma_convert_kvec(struct kvec *vec, struct rpcrdma_mr_seg *seg,
 		     unsigned int *n)
 {
-	u32 remaining, page_offset;
-	char *base;
-
-	base = vec->iov_base;
-	page_offset = offset_in_page(base);
-	remaining = vec->iov_len;
-	while (remaining) {
+	if (vec->iov_len) {
 		seg->mr_page = NULL;
-		seg->mr_offset = base;
-		seg->mr_len = min_t(u32, PAGE_SIZE - page_offset, remaining);
-		remaining -= seg->mr_len;
-		base += seg->mr_len;
+		seg->mr_offset = vec->iov_base;
+		seg->mr_len = vec->iov_len;
 		++seg;
 		++(*n);
-		page_offset = 0;
 	}
 	return seg;
 }