nfsd4: adjust buflen for encoded attrs bitmap based on actual bitmap length

The existing code adjusted it based on the worst case scenario for the returned
bitmap and the best case scenario for the supported attrs attribute.
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[bfields@redhat.com: removed likely/unlikely's]
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4xdr.c

@@ -1805,19 +1805,23 @@ nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp,
 				goto out_nfserr;
 		}
 	}
-	if ((buflen -= 16) < 0)
-		goto out_resource;
 
-	if (unlikely(bmval2)) {
+	if (bmval2) {
+		if ((buflen -= 16) < 0)
+			goto out_resource;
 		WRITE32(3);
 		WRITE32(bmval0);
 		WRITE32(bmval1);
 		WRITE32(bmval2);
-	} else if (likely(bmval1)) {
+	} else if (bmval1) {
+		if ((buflen -= 12) < 0)
+			goto out_resource;
 		WRITE32(2);
 		WRITE32(bmval0);
 		WRITE32(bmval1);
 	} else {
+		if ((buflen -= 8) < 0)
+			goto out_resource;
 		WRITE32(1);
 		WRITE32(bmval0);
 	}
@@ -1828,15 +1832,17 @@ nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp,
 		u32 word1 = nfsd_suppattrs1(minorversion);
 		u32 word2 = nfsd_suppattrs2(minorversion);
 
-		if ((buflen -= 12) < 0)
-			goto out_resource;
 		if (!aclsupport)
 			word0 &= ~FATTR4_WORD0_ACL;
 		if (!word2) {
+			if ((buflen -= 12) < 0)
+				goto out_resource;
 			WRITE32(2);
 			WRITE32(word0);
 			WRITE32(word1);
 		} else {
+			if ((buflen -= 16) < 0)
+				goto out_resource;
 			WRITE32(3);
 			WRITE32(word0);
 			WRITE32(word1);