So that NFS WRITE payloads can eventually be placed directly into a
file's page cache, enable the RPC-over-RDMA transport to present
these payloads in the xdr_buf's page list, while placing trailing
content (such as a GETATTR operation) in the xdr_buf's tail.
After this change, the RPC-over-RDMA's "copy tail" hack, added by
commit a97c331f9aa9 ("svcrdma: Handle additional inline content"),
is no longer needed and can be removed.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
net/sunrpc/xprtrdma/svc_rdma_rw.c | 108 +++++--------------------------------
1 file changed, 15 insertions(+), 93 deletions(-)
diff --git a/net/sunrpc/xprtrdma/svc_rdma_rw.c b/net/sunrpc/xprtrdma/svc_rdma_rw.c
index 1f34fae..7dcda45 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_rw.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_rw.c
@@ -691,78 +691,6 @@ static int svc_rdma_build_read_chunk(struct svc_rqst *rqstp,
return ret;
}
-/* If there is inline content following the Read chunk, append it to
- * the page list immediately following the data payload. This has to
- * be done after the reader function has determined how many pages
- * were consumed for RDMA Read.
- *
- * On entry, ri_pageno and ri_pageoff point directly to the end of the
- * page list. On exit, both have been updated to the new "next byte".
- *
- * Assumptions:
- * - Inline content fits entirely in rq_pages[0]
- * - Trailing content is only a handful of bytes
- */
-static int svc_rdma_copy_tail(struct svc_rqst *rqstp,
- struct svc_rdma_read_info *info)
-{
- struct svc_rdma_op_ctxt *head = info->ri_readctxt;
- unsigned int tail_length, remaining;
- u8 *srcp, *destp;
-
- /* Assert that all inline content fits in page 0. This is an
- * implementation limit, not a protocol limit.
- */
- if (head->arg.head[0].iov_len > PAGE_SIZE) {
- pr_warn_once("svcrdma: too much trailing inline content\n");
- return -EINVAL;
- }
-
- srcp = head->arg.head[0].iov_base;
- srcp += info->ri_position;
- tail_length = head->arg.head[0].iov_len - info->ri_position;
- remaining = tail_length;
-
- /* If there is room on the last page in the page list, try to
- * fit the trailing content there.
- */
- if (info->ri_pageoff > 0) {
- unsigned int len;
-
- len = min_t(unsigned int, remaining,
- PAGE_SIZE - info->ri_pageoff);
- destp = page_address(rqstp->rq_pages[info->ri_pageno]);
- destp += info->ri_pageoff;
-
- memcpy(destp, srcp, len);
- srcp += len;
- destp += len;
- info->ri_pageoff += len;
- remaining -= len;
-
- if (info->ri_pageoff == PAGE_SIZE) {
- info->ri_pageno++;
- info->ri_pageoff = 0;
- }
- }
-
- /* Otherwise, a fresh page is needed. */
- if (remaining) {
- head->arg.pages[info->ri_pageno] =
- rqstp->rq_pages[info->ri_pageno];
- head->count++;
-
- destp = page_address(rqstp->rq_pages[info->ri_pageno]);
- memcpy(destp, srcp, remaining);
- info->ri_pageoff += remaining;
- }
-
- head->arg.page_len += tail_length;
- head->arg.len += tail_length;
- head->arg.buflen += tail_length;
- return 0;
-}
-
/* Construct RDMA Reads to pull over a normal Read chunk. The chunk
* data lands in the page list of head->arg.pages.
*
@@ -787,34 +715,28 @@ static int svc_rdma_build_normal_read_chunk(struct svc_rqst *rqstp,
if (ret < 0)
goto out;
- /* Read chunk may need XDR round-up (see RFC 5666, s. 3.7).
+ /* Split the Receive buffer between the head and tail
+ * buffers at Read chunk's position. XDR roundup of the
+ * chunk is not included in either the pagelist or in
+ * the tail.
*/
- if (info->ri_chunklen & 3) {
- u32 padlen = 4 - (info->ri_chunklen & 3);
-
- info->ri_chunklen += padlen;
+ head->arg.tail[0].iov_base =
+ head->arg.head[0].iov_base + info->ri_position;
+ head->arg.tail[0].iov_len =
+ head->arg.head[0].iov_len - info->ri_position;
+ head->arg.head[0].iov_len = info->ri_position;
- /* NB: data payload always starts on XDR alignment,
- * thus the pad can never contain a page boundary.
- */
- info->ri_pageoff += padlen;
- if (info->ri_pageoff == PAGE_SIZE) {
- info->ri_pageno++;
- info->ri_pageoff = 0;
- }
- }
+ /* Read chunk may need XDR roundup (see RFC 5666, s. 3.7).
+ *
+ * NFSv2/3 write decoders need the length of the tail to
+ * contain the size of the roundup padding.
+ */
+ head->arg.tail[0].iov_len += 4 - (info->ri_chunklen & 3);
head->arg.page_len = info->ri_chunklen;
head->arg.len += info->ri_chunklen;
head->arg.buflen += info->ri_chunklen;
- if (info->ri_position < head->arg.head[0].iov_len) {
- ret = svc_rdma_copy_tail(rqstp, info);
- if (ret < 0)
- goto out;
- }
- head->arg.head[0].iov_len = info->ri_position;
-
out:
return ret;
}
--
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