NFSD: fix regression with setting ACLs.

A recent patch moved ACL setting into nfsd_setattr().
Unfortunately it didn't work as nfsd_setattr() aborts early if
iap->ia_valid is 0.

Remove this test, and instead avoid calling notify_change() when
ia_valid is 0.

This means that nfsd_setattr() will now *always* lock the inode.
Previously it didn't if only a ATTR_MODE change was requested on a
symlink (see Commit 15b7a1b8 ("[PATCH] knfsd: fix setattr-on-symlink
error return")). I don't think this change really matters.

Fixes: c0cbe707 ("NFSD: add posix ACLs to struct nfsd_attrs")
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

fs/nfsd/vfs.c

@@ -300,6 +300,10 @@ commit_metadata(struct svc_fh *fhp)
 static void
 nfsd_sanitize_attrs(struct inode *inode, struct iattr *iap)
 {
+	/* Ignore mode updates on symlinks */
+	if (S_ISLNK(inode->i_mode))
+		iap->ia_valid &= ~ATTR_MODE;
+
 	/* sanitize the mode change */
 	if (iap->ia_valid & ATTR_MODE) {
 		iap->ia_mode &= S_IALLUGO;
@@ -353,7 +357,7 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	int		accmode = NFSD_MAY_SATTR;
 	umode_t		ftype = 0;
 	__be32		err;
-	int		host_err;
+	int		host_err = 0;
 	bool		get_write_count;
 	bool		size_change = (iap->ia_valid & ATTR_SIZE);
 
@@ -391,13 +395,6 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
 	dentry = fhp->fh_dentry;
 	inode = d_inode(dentry);
 
-	/* Ignore any mode updates on symlinks */
-	if (S_ISLNK(inode->i_mode))
-		iap->ia_valid &= ~ATTR_MODE;
-
-	if (!iap->ia_valid)
-		return 0;
-
 	nfsd_sanitize_attrs(inode, iap);
 
 	if (check_guard && guardtime != inode->i_ctime.tv_sec)
@@ -448,8 +445,10 @@ nfsd_setattr(struct svc_rqst *rqstp, struct svc_fh *fhp,
 			goto out_unlock;
 	}
 
+	if (iap->ia_valid) {
 		iap->ia_valid |= ATTR_CTIME;
 		host_err = notify_change(&init_user_ns, dentry, iap, NULL);
+	}
 
 out_unlock:
 	if (attr->na_seclabel && attr->na_seclabel->len)