[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, 13 insertions, 14 deletions

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 5be00436b5b8..9f30c53ac0ed 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -2039,7 +2039,8 @@ nfsd4_encode_open_downgrade(struct nfsd4_compoundres *resp, int nfserr, struct n
 }
 
 static int
-nfsd4_encode_read(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_read *read)
+nfsd4_encode_read(struct nfsd4_compoundres *resp, int nfserr,
+		  struct nfsd4_read *read)
 {
 	u32 eof;
 	int v, pn;
@@ -2061,10 +2062,11 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_read
 	len = maxcount;
 	v = 0;
 	while (len > 0) {
-		pn = resp->rqstp->rq_resused;
-		svc_take_page(resp->rqstp);
-		read->rd_iov[v].iov_base = page_address(resp->rqstp->rq_respages[pn]);
-		read->rd_iov[v].iov_len = len < PAGE_SIZE ? len : PAGE_SIZE;
+		pn = resp->rqstp->rq_resused++;
+		read->rd_iov[v].iov_base =
+			page_address(resp->rqstp->rq_respages[pn]);
+		read->rd_iov[v].iov_len =
+			len < PAGE_SIZE ? len : PAGE_SIZE;
 		v++;
 		len -= PAGE_SIZE;
 	}
@@ -2078,7 +2080,8 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_read
 		nfserr = nfserr_inval;
 	if (nfserr)
 		return nfserr;
-	eof = (read->rd_offset + maxcount >= read->rd_fhp->fh_dentry->d_inode->i_size);
+	eof = (read->rd_offset + maxcount >=
+	       read->rd_fhp->fh_dentry->d_inode->i_size);
 
 	WRITE32(eof);
 	WRITE32(maxcount);
@@ -2088,7 +2091,6 @@ nfsd4_encode_read(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_read
 	resp->xbuf->page_len = maxcount;
 
 	/* Use rest of head for padding and remaining ops: */
-	resp->rqstp->rq_restailpage = 0;
 	resp->xbuf->tail[0].iov_base = p;
 	resp->xbuf->tail[0].iov_len = 0;
 	if (maxcount&3) {
@@ -2113,8 +2115,7 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_r
 	if (resp->xbuf->page_len)
 		return nfserr_resource;
 
-	svc_take_page(resp->rqstp);
-	page = page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused-1]);
+	page = page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused++]);
 
 	maxcount = PAGE_SIZE;
 	RESERVE_SPACE(4);
@@ -2138,7 +2139,6 @@ nfsd4_encode_readlink(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_r
 	resp->xbuf->page_len = maxcount;
 
 	/* Use rest of head for padding and remaining ops: */
-	resp->rqstp->rq_restailpage = 0;
 	resp->xbuf->tail[0].iov_base = p;
 	resp->xbuf->tail[0].iov_len = 0;
 	if (maxcount&3) {
@@ -2189,8 +2189,7 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_re
 		goto err_no_verf;
 	}
 
-	svc_take_page(resp->rqstp);
-	page = page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused-1]);
+	page = page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused++]);
 	readdir->common.err = 0;
 	readdir->buflen = maxcount;
 	readdir->buffer = page;
@@ -2215,10 +2214,10 @@ nfsd4_encode_readdir(struct nfsd4_compoundres *resp, int nfserr, struct nfsd4_re
 	p = readdir->buffer;
 	*p++ = 0;	/* no more entries */
 	*p++ = htonl(readdir->common.err == nfserr_eof);
-	resp->xbuf->page_len = ((char*)p) - (char*)page_address(resp->rqstp->rq_respages[resp->rqstp->rq_resused-1]);
+	resp->xbuf->page_len = ((char*)p) - (char*)page_address(
+		resp->rqstp->rq_respages[resp->rqstp->rq_resused-1]);
 
 	/* Use rest of head for padding and remaining ops: */
-	resp->rqstp->rq_restailpage = 0;
 	resp->xbuf->tail[0].iov_base = tailbase;
 	resp->xbuf->tail[0].iov_len = 0;
 	resp->p = resp->xbuf->tail[0].iov_base;