svcrdma: Clean up Read chunk path

Simplify the error handling at the tail of recv_read_chunk() by
re-arranging rq_pages[] housekeeping and documenting it properly.

NB: In this path, svc_rdma_recvfrom returns zero. Therefore no
subsequent reply processing is done on the svc_rqstp, and thus the
rq_respages field does not need to be updated.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --git a/net/sunrpc/xprtrdma/svc_rdma_rw.c b/net/sunrpc/xprtrdma/svc_rdma_rw.c
index ce3ea8419704839cc48c050a134070ac3a7a864f..a1ac9997da98df63b1eaa547cf6b569f55d16381 100644 (file)
--- a/net/sunrpc/xprtrdma/svc_rdma_rw.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_rw.c
@@ -679,6 +679,7 @@ static int svc_rdma_build_read_chunk(struct svc_rqst *rqstp,
                                     struct svc_rdma_read_info *info,
                                     __be32 *p)
 {
+       unsigned int i;
        int ret;
 
        ret = -EINVAL;
@@ -701,6 +702,12 @@ static int svc_rdma_build_read_chunk(struct svc_rqst *rqstp,
                info->ri_chunklen += rs_length;
        }
 
+       /* Pages under I/O have been copied to head->rc_pages.
+        * Prevent their premature release by svc_xprt_release() .
+        */
+       for (i = 0; i < info->ri_readctxt->rc_page_count; i++)
+               rqstp->rq_pages[i] = NULL;
+
        return ret;
 }
 
@@ -816,7 +823,6 @@ int svc_rdma_recv_read_chunk(struct svcxprt_rdma *rdma, struct svc_rqst *rqstp,
                             struct svc_rdma_recv_ctxt *head, __be32 *p)
 {
        struct svc_rdma_read_info *info;
-       struct page **page;
        int ret;
 
        /* The request (with page list) is constructed in
@@ -843,27 +849,15 @@ int svc_rdma_recv_read_chunk(struct svcxprt_rdma *rdma, struct svc_rqst *rqstp,
                ret = svc_rdma_build_normal_read_chunk(rqstp, info, p);
        else
                ret = svc_rdma_build_pz_read_chunk(rqstp, info, p);
-
-       /* Mark the start of the pages that can be used for the reply */
-       if (info->ri_pageoff > 0)
-               info->ri_pageno++;
-       rqstp->rq_respages = &rqstp->rq_pages[info->ri_pageno];
-       rqstp->rq_next_page = rqstp->rq_respages + 1;
-
        if (ret < 0)
-               goto out;
+               goto out_err;
 
        ret = svc_rdma_post_chunk_ctxt(&info->ri_cc);
-
-out:
-       /* Read sink pages have been moved from rqstp->rq_pages to
-        * head->rc_arg.pages. Force svc_recv to refill those slots
-        * in rq_pages.
-        */
-       for (page = rqstp->rq_pages; page < rqstp->rq_respages; page++)
-               *page = NULL;
-
        if (ret < 0)
-               svc_rdma_read_info_free(info);
+               goto out_err;
+       return 0;
+
+out_err:
+       svc_rdma_read_info_free(info);
        return ret;
 }