[PATCH 24/52] nfsd4: remove redundant encode buffer size checking

["J. Bruce Fields" <bfields@redhat.com>]

From: "J. Bruce Fields" <bfields@redhat.com>

Now that all op encoders can handle running out of space, we no longer
need to check the remaining size for every operation; only nonidempotent
operations need that check, and that can be done by
nfsd4_check_resp_size.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
 fs/nfsd/nfs4proc.c | 14 --------------
 fs/nfsd/nfs4xdr.c  | 22 +++++++++++++---------
 2 files changed, 13 insertions(+), 23 deletions(-)

diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 694e1a5..9b57894 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -1281,7 +1281,6 @@ nfsd4_proc_compound(struct svc_rqst *rqstp,
 	struct nfsd4_compound_state *cstate = &resp->cstate;
 	struct svc_fh *current_fh = &cstate->current_fh;
 	struct svc_fh *save_fh = &cstate->save_fh;
-	int		slack_bytes;
 	u32		plen = 0;
 	__be32		status;
 
@@ -1335,19 +1334,6 @@ nfsd4_proc_compound(struct svc_rqst *rqstp,
 			goto encode_op;
 		}
 
-		/* We must be able to encode a successful response to
-		 * this operation, with enough room left over to encode a
-		 * failed response to the next operation.  If we don't
-		 * have enough room, fail with ERR_RESOURCE.
-		 */
-		slack_bytes = (char *)resp->xdr.end - (char *)resp->xdr.p;
-		if (slack_bytes < COMPOUND_SLACK_SPACE
-				+ COMPOUND_ERR_SLACK_SPACE) {
-			BUG_ON(slack_bytes < COMPOUND_ERR_SLACK_SPACE);
-			op->status = nfserr_resource;
-			goto encode_op;
-		}
-
 		opdesc = OPDESC(op);
 
 		if (!current_fh->fh_dentry) {
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index be5793f..86caa98 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -3753,20 +3753,24 @@ static nfsd4_enc nfsd4_enc_ops[] = {
 __be32 nfsd4_check_resp_size(struct nfsd4_compoundres *resp, u32 pad)
 {
 	struct xdr_buf *buf = &resp->rqstp->rq_res;
-	struct nfsd4_session *session = NULL;
+	struct nfsd4_session *session = resp->cstate.session;
 	struct nfsd4_slot *slot = resp->cstate.slot;
+	int slack_bytes = (char *)resp->xdr.end - (char *)resp->xdr.p;
 
-	if (!nfsd4_has_session(&resp->cstate))
-		return 0;
+	if (nfsd4_has_session(&resp->cstate)) {
 
-	session = resp->cstate.session;
+		if (buf->len + pad > session->se_fchannel.maxresp_sz)
+			return nfserr_rep_too_big;
 
-	if (buf->len + pad > session->se_fchannel.maxresp_sz)
-		return nfserr_rep_too_big;
+		if ((slot->sl_flags & NFSD4_SLOT_CACHETHIS) &&
+		    buf->len + pad > session->se_fchannel.maxresp_cached)
+			return nfserr_rep_too_big_to_cache;
+	}
 
-	if ((slot->sl_flags & NFSD4_SLOT_CACHETHIS) &&
-	    buf->len + pad > session->se_fchannel.maxresp_cached)
-		return nfserr_rep_too_big_to_cache;
+	if (pad > slack_bytes) {
+		WARN_ON_ONCE(nfsd4_has_session(&resp->cstate));
+		return nfserr_resource;
+	}
 
 	return 0;
 }
-- 
1.9.0