nfsd4: more precise nfsd4_max_reply

It will turn out to be useful to have a more accurate estimate of reply
size; so, piggyback on the existing op reply-size estimators.

Also move nfsd4_max_reply to nfs4proc.c to get easier access to struct
nfsd4_operation and friends.  (Thanks to Christoph Hellwig for pointing
out that simplification.)

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

1 files changed, 4 insertions, 31 deletions

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 2f0ea20edb2..8b3d24de9ca 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1605,40 +1605,13 @@ nfsd4_opnum_in_range(struct nfsd4_compoundargs *argp, struct nfsd4_op *op)
 	return true;
 }
 
-/*
- * Return a rough estimate of the maximum possible reply size.  Note the
- * estimate includes rpc headers so is meant to be passed to
- * svc_reserve, not svc_reserve_auth.
- *
- * Also note the current compound encoding permits only one operation to
- * use pages beyond the first one, so the maximum possible length is the
- * maximum over these values, not the sum.
- */
-static int nfsd4_max_reply(u32 opnum)
-{
-	switch (opnum) {
-	case OP_READLINK:
-	case OP_READDIR:
-		/*
-		 * Both of these ops take a single page for data and put
-		 * the head and tail in another page:
-		 */
-		return 2 * PAGE_SIZE;
-	case OP_GETATTR:
-	case OP_READ:
-		return INT_MAX;
-	default:
-		return PAGE_SIZE;
-	}
-}
-
 static __be32
 nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
 {
 	DECODE_HEAD;
 	struct nfsd4_op *op;
 	bool cachethis = false;
-	int max_reply = PAGE_SIZE;
+	int max_reply = 2 * RPC_MAX_AUTH_SIZE + 8; /* opcnt, status */
 	int i;
 
 	READ_BUF(4);
@@ -1647,6 +1620,7 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
 	SAVEMEM(argp->tag, argp->taglen);
 	READ32(argp->minorversion);
 	READ32(argp->opcnt);
+	max_reply += 4 + (XDR_QUADLEN(argp->taglen) << 2);
 
 	if (argp->taglen > NFSD4_MAX_TAGLEN)
 		goto xdr_error;
@@ -1684,7 +1658,7 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
 		 */
 		cachethis |= nfsd4_cache_this_op(op);
 
-		max_reply = max(max_reply, nfsd4_max_reply(op->opnum));
+		max_reply += nfsd4_max_reply(argp->rqstp, op);
 
 		if (op->status) {
 			argp->opcnt = i+1;
@@ -1694,8 +1668,7 @@ nfsd4_decode_compound(struct nfsd4_compoundargs *argp)
 	/* Sessions make the DRC unnecessary: */
 	if (argp->minorversion)
 		cachethis = false;
-	if (max_reply != INT_MAX)
-		svc_reserve(argp->rqstp, max_reply);
+	svc_reserve(argp->rqstp, max_reply);
 	argp->rqstp->rq_cachetype = cachethis ? RC_REPLBUFF : RC_NOCACHE;
 
 	DECODE_TAIL;