[PATCH] knfsd: Replace two page lists in struct svc_rqst with one

We are planning to increase RPCSVC_MAXPAGES from about 8 to about 256.  This
means we need to be a bit careful about arrays of size RPCSVC_MAXPAGES.

struct svc_rqst contains two such arrays.  However the there are never more
that RPCSVC_MAXPAGES pages in the two arrays together, so only one array is
needed.

The two arrays are for the pages holding the request, and the pages holding
the reply.  Instead of two arrays, we can simply keep an index into where the
first reply page is.

This patch also removes a number of small inline functions that probably
server to obscure what is going on rather than clarify it, and opencode the
needed functionality.

Also remove the 'rq_restailpage' variable as it is *always* 0.  i.e.  if the
response 'xdr' structure has a non-empty tail it is always in the same pages
as the head.

 check counters are initilised and incr properly
 check for consistant usage of ++ etc
 maybe extra some inlines for common approach
 general review

Signed-off-by: Neil Brown <neilb@suse.de>
Cc: Magnus Maatta <novell@kiruna.se>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 9 insertions, 14 deletions

diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 243d94b9653a..20ba728a4642 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -343,8 +343,7 @@ nfs3svc_decode_readargs(struct svc_rqst *rqstp, u32 *p,
         /* set up the kvec */
         v=0;
         while (len > 0) {
-                pn = rqstp->rq_resused;
-                svc_take_page(rqstp);
+                pn = rqstp->rq_resused++;
                 args->vec[v].iov_base = page_address(rqstp->rq_respages[pn]);
                 args->vec[v].iov_len = len < PAGE_SIZE? len : PAGE_SIZE;
                 len -= args->vec[v].iov_len;
@@ -382,7 +381,7 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, u32 *p,
         while (len > args->vec[v].iov_len) {
                 len -= args->vec[v].iov_len;
                 v++;
-                args->vec[v].iov_base = page_address(rqstp->rq_argpages[v]);
+                args->vec[v].iov_base = page_address(rqstp->rq_pages[v]);
                 args->vec[v].iov_len = PAGE_SIZE;
         }
         args->vec[v].iov_len = len;
@@ -446,11 +445,11 @@ nfs3svc_decode_symlinkargs(struct svc_rqst *rqstp, u32 *p,
          * This page appears in the rq_res.pages list, but as pages_len is always
          * 0, it won't get in the way
          */
-        svc_take_page(rqstp);
         len = ntohl(*p++);
         if (len == 0 || len > NFS3_MAXPATHLEN || len >= PAGE_SIZE)
                 return 0;
-        args->tname = new = page_address(rqstp->rq_respages[rqstp->rq_resused-1]);
+        args->tname = new =
+                page_address(rqstp->rq_respages[rqstp->rq_resused++]);
         args->tlen = len;
         /* first copy and check from the first page */
         old = (char*)p;
@@ -522,8 +521,8 @@ nfs3svc_decode_readlinkargs(struct svc_rqst *rqstp, u32 *p,
 {
         if (!(p = decode_fh(p, &args->fh)))
                 return 0;
-        svc_take_page(rqstp);
-        args->buffer = page_address(rqstp->rq_respages[rqstp->rq_resused-1]);
+        args->buffer =
+                page_address(rqstp->rq_respages[rqstp->rq_resused++]);
 
         return xdr_argsize_check(rqstp, p);
 }
@@ -554,8 +553,8 @@ nfs3svc_decode_readdirargs(struct svc_rqst *rqstp, u32 *p,
         if (args->count > PAGE_SIZE)
                 args->count = PAGE_SIZE;
 
-        svc_take_page(rqstp);
-        args->buffer = page_address(rqstp->rq_respages[rqstp->rq_resused-1]);
+        args->buffer =
+                page_address(rqstp->rq_respages[rqstp->rq_resused++]);
 
         return xdr_argsize_check(rqstp, p);
 }
@@ -578,8 +577,7 @@ nfs3svc_decode_readdirplusargs(struct svc_rqst *rqstp, u32 *p,
         args->count = len;
 
         while (len > 0) {
-                pn = rqstp->rq_resused;
-                svc_take_page(rqstp);
+                pn = rqstp->rq_resused++;
                 if (!args->buffer)
                         args->buffer = page_address(rqstp->rq_respages[pn]);
                 len -= PAGE_SIZE;
@@ -668,7 +666,6 @@ nfs3svc_encode_readlinkres(struct svc_rqst *rqstp, u32 *p,
                 rqstp->rq_res.page_len = resp->len;
                 if (resp->len & 3) {
                         /* need to pad the tail */
-                        rqstp->rq_restailpage = 0;
                         rqstp->rq_res.tail[0].iov_base = p;
                         *p = 0;
                         rqstp->rq_res.tail[0].iov_len = 4 - (resp->len&3);
@@ -693,7 +690,6 @@ nfs3svc_encode_readres(struct svc_rqst *rqstp, u32 *p,
                 rqstp->rq_res.page_len = resp->count;
                 if (resp->count & 3) {
                         /* need to pad the tail */
-                        rqstp->rq_restailpage = 0;
                         rqstp->rq_res.tail[0].iov_base = p;
                         *p = 0;
                         rqstp->rq_res.tail[0].iov_len = 4 - (resp->count & 3);
@@ -768,7 +764,6 @@ nfs3svc_encode_readdirres(struct svc_rqst *rqstp, u32 *p,
                 rqstp->rq_res.page_len = (resp->count) << 2;
 
                 /* add the 'tail' to the end of the 'head' page - page 0. */
-                rqstp->rq_restailpage = 0;
                 rqstp->rq_res.tail[0].iov_base = p;
                 *p++ = 0;               /* no more entries */
                 *p++ = htonl(resp->common.err == nfserr_eof);