From: Jeff Layton <jlayton@redhat.com>
Date: Tue, 13 Oct 2009 09:14:09 -0400
Subject: [nfs] knfsd: query fs for v4 getattr of FATTR4_MAXNAME
Message-id: 1255439649-14262-1-git-send-email-jlayton@redhat.com
O-Subject: [RHEL5.5 PATCH] BZ#469689: knfsd: query filesystem for NFSv4 getattr of FATTR4_MAXNAME
Bugzilla: 469689
RH-Acked-by: Steve Dickson <SteveD@redhat.com>
RH-Acked-by: Steve Dickson <SteveD@redhat.com>

(backported from a16e92edcd0a2846455a30823e1bac964e743baa)

When a program calls pathconf on a file on NFSv4, it always returns
2^32-1, which apparently indicates that there is no limit. This patch
fixes it so that the NFS server queries the underlying filesystem for
the maximum name length and returns that value instead.

Tested by the reporter of this bug and myself using a simple program
that calls pathconf(..., _PC_NAME_MAX) on a file.

diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 227b9b7..b65b915 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -1443,7 +1443,8 @@ nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp,
 	status = vfs_getattr(exp->ex_mnt, dentry, &stat);
 	if (status)
 		goto out_nfserr;
-	if ((bmval0 & (FATTR4_WORD0_FILES_FREE | FATTR4_WORD0_FILES_TOTAL)) ||
+	if ((bmval0 & (FATTR4_WORD0_FILES_FREE | FATTR4_WORD0_FILES_TOTAL |
+			FATTR4_WORD0_MAXNAME)) ||
 	    (bmval1 & (FATTR4_WORD1_SPACE_AVAIL | FATTR4_WORD1_SPACE_FREE |
 		       FATTR4_WORD1_SPACE_TOTAL))) {
 		status = vfs_statfs(dentry, &statfs);
@@ -1680,7 +1681,7 @@ out_acl:
 	if (bmval0 & FATTR4_WORD0_MAXNAME) {
 		if ((buflen -= 4) < 0)
 			goto out_resource;
-		WRITE32(~(u32) 0);
+		WRITE32(statfs.f_namelen);
 	}
 	if (bmval0 & FATTR4_WORD0_MAXREAD) {
 		if ((buflen -= 8) < 0)