SUNRPC: Don't return error values in sysfs read of closed files

Instead of returning an error value, which ends up being the return
value for the read() system call, it is more elegant to simply return
the error as a string value.
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

net/sunrpc/sysfs.c

@@ -93,10 +93,13 @@ static ssize_t rpc_sysfs_xprt_dstaddr_show(struct kobject *kobj,
 	struct rpc_xprt *xprt = rpc_sysfs_xprt_kobj_get_xprt(kobj);
 	ssize_t ret;
 
-	if (!xprt)
-		return 0;
+	if (!xprt) {
+		ret = sprintf(buf, "<closed>\n");
+		goto out;
+	}
 	ret = sprintf(buf, "%s\n", xprt->address_strings[RPC_DISPLAY_ADDR]);
 	xprt_put(xprt);
+out:
 	return ret;
 }
 
@@ -106,10 +109,10 @@ static ssize_t rpc_sysfs_xprt_srcaddr_show(struct kobject *kobj,
 {
 	struct rpc_xprt *xprt = rpc_sysfs_xprt_kobj_get_xprt(kobj);
 	size_t buflen = PAGE_SIZE;
-	ssize_t ret = -ENOTSOCK;
+	ssize_t ret;
 
 	if (!xprt || !xprt_connected(xprt)) {
-		ret = -ENOTCONN;
+		ret = sprintf(buf, "<closed>\n");
 	} else if (xprt->ops->get_srcaddr) {
 		ret = xprt->ops->get_srcaddr(xprt, buf, buflen);
 		if (ret > 0) {
@@ -118,8 +121,10 @@ static ssize_t rpc_sysfs_xprt_srcaddr_show(struct kobject *kobj,
 				ret++;
 				buf[ret] = '\0';
 			}
-		}
-	}
+		} else
+			ret = sprintf(buf, "<closed>\n");
+	} else
+		ret = sprintf(buf, "<not a socket>\n");
 	xprt_put(xprt);
 	return ret;
 }
@@ -133,8 +138,8 @@ static ssize_t rpc_sysfs_xprt_info_show(struct kobject *kobj,
 	ssize_t ret;
 
 	if (!xprt || !xprt_connected(xprt)) {
-		xprt_put(xprt);
-		return -ENOTCONN;
+		ret = sprintf(buf, "<closed>\n");
+		goto out;
 	}
 
 	if (xprt->ops->get_srcport)
@@ -152,6 +157,7 @@ static ssize_t rpc_sysfs_xprt_info_show(struct kobject *kobj,
 		       xprt->backlog.qlen, xprt->main, srcport,
 		       atomic_long_read(&xprt->queuelen),
 		       xprt->address_strings[RPC_DISPLAY_PORT]);
+out:
 	xprt_put(xprt);
 	return ret;
 }
@@ -165,10 +171,7 @@ static ssize_t rpc_sysfs_xprt_state_show(struct kobject *kobj,
 	int locked, connected, connecting, close_wait, bound, binding,
 	    closing, congested, cwnd_wait, write_space, offline, remove;
 
-	if (!xprt)
-		return 0;
-
-	if (!xprt->state) {
+	if (!(xprt && xprt->state)) {
 		ret = sprintf(buf, "state=CLOSED\n");
 	} else {
 		locked = test_bit(XPRT_LOCKED, &xprt->state);