[2/7] fedfsd: Flush kernel's exports cache after junction operations

diff --git a/src/fedfsd/svc.c b/src/fedfsd/svc.c
index 316042f..6d548c1 100644
--- a/src/fedfsd/svc.c
+++ b/src/fedfsd/svc.c
@@ -538,15 +538,16 @@  fedfsd_svc_create_junction_1(SVCXPRT *xprt)
 	}
 
 	result = fedfs_store_fsn(pathname, fsn_uuid, host);
-	if (result != FEDFS_OK)
+	if (result != FEDFS_OK) {
 		xlog(D_GENERAL, "%s: fedfs_store_fsn", __func__);
-	else {
-		xlog(D_CALL, "%s: uuid: %s",
-			__func__, fsn_uuid);
-		xlog(D_CALL, "%s: nsdb: %s:%u",
-			__func__, nsdb_hostname(host), nsdb_port(host));
+		goto out;
 	}
 
+	(void)junction_flush_exports_cache();
+	xlog(D_CALL, "%s: uuid: %s", __func__, fsn_uuid);
+	xlog(D_CALL, "%s: nsdb: %s:%u",
+			__func__, nsdb_hostname(host), nsdb_port(host));
+
 out:
 	xlog(D_CALL, "%s: Replying with %s",
 			__func__, nsdb_display_fedfsstatus(result));
@@ -643,6 +644,7 @@  fedfsd_svc_delete_junction_1(SVCXPRT *xprt)
 		goto out;
 
 	fedfsd_rmdir(pathname);
+	(void)junction_flush_exports_cache();
 	result = FEDFS_OK;
 
 out:
@@ -800,9 +802,11 @@  fedfsd_svc_lookup_junction_1(SVCXPRT *xprt)
 	result.status = FEDFS_ERR_BADXDR;
 	switch (args.resolve) {
 	case FEDFS_RESOLVE_NONE:
-	case FEDFS_RESOLVE_CACHE:
 	case FEDFS_RESOLVE_NSDB:
 		break;
+	case FEDFS_RESOLVE_CACHE:
+		result.status = FEDFS_ERR_UNKNOWN_CACHE;
+		goto out;
 	default:
 		goto out;
 	}
@@ -839,7 +843,6 @@  fedfsd_svc_lookup_junction_1(SVCXPRT *xprt)
 
 	switch (args.resolve) {
 	case FEDFS_RESOLVE_NONE:
-	case FEDFS_RESOLVE_CACHE:
 		break;
 	case FEDFS_RESOLVE_NSDB:
 		result.status = nsdb_open_nsdb(host, NULL, NULL, &ldap_err);
@@ -857,6 +860,12 @@  fedfsd_svc_lookup_junction_1(SVCXPRT *xprt)
 			break;
 		result.status = fedfsd_prepare_fedfsfsl_array(fsls, resok);
 		nsdb_free_fedfs_fsls(fsls);
+		if (result.status != FEDFS_OK)
+			break;
+		result.status = junction_flush_exports_cache();
+		if (result.status != FEDFS_OK &&
+		    result.status != FEDFS_ERR_NO_CACHE_UPDATE)
+			result.status = FEDFS_OK;
 		break;
 	default:
 		result.status = FEDFS_ERR_SVRFAULT;
diff --git a/src/include/junction.h b/src/include/junction.h
index e09cf5b..edbab7b 100644
--- a/src/include/junction.h
+++ b/src/include/junction.h
@@ -39,4 +39,6 @@  FedFsStatus	 fedfs_is_junction(const char *pathname);
 FedFsStatus	 fedfs_save_mode(const char *pathname);
 FedFsStatus	 fedfs_restore_mode(const char *pathname);
 
+FedFsStatus	 junction_flush_exports_cache(void);
+
 #endif	/* !_FEDFS_JUNCTION_H_ */
diff --git a/src/libjunction/Makefile.am b/src/libjunction/Makefile.am
index bc97bf3..4c43e66 100644
--- a/src/libjunction/Makefile.am
+++ b/src/libjunction/Makefile.am
@@ -24,7 +24,7 @@ 
 ##
 
 noinst_LTLIBRARIES	= libjunction.la
-libjunction_la_SOURCES	= junction.c
+libjunction_la_SOURCES	= export-cache.c junction.c
 
 CLEANFILES		= cscope.in.out cscope.out cscope.po.out *~
 DISTCLEANFILES		= Makefile.in
diff --git a/src/libjunction/export-cache.c b/src/libjunction/export-cache.c
new file mode 100644
index 0000000..e344547
--- /dev/null
+++ b/src/libjunction/export-cache.c
@@ -0,0 +1,121 @@ 
+/**
+ * @file src/libjunction/export-cache.c
+ * @brief Try to flush NFSD's exports cache
+ */
+
+/*
+ * Copyright 2011 Oracle.  All rights reserved.
+ *
+ * This file is part of fedfs-utils.
+ *
+ * fedfs-utils is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2.0 as
+ * published by the Free Software Foundation.
+ *
+ * fedfs-utils is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License version 2.0 for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * version 2.0 along with fedfs-utils.  If not, see:
+ *
+ *	http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+//#include <errno.h>
+#include <time.h>
+
+
+#include "fedfs.h"
+#include "nsdb.h"
+#include "junction.h"
+#include "xlog.h"
+
+/**
+ * Ordered list of proc files to poke when requesting an NFSD cache flush
+ */
+static const char *junction_proc_files[] = {
+	"/proc/net/rpc/auth.unix.ip/flush",
+	"/proc/net/rpc/auth.unix.gid/flush",
+	"/proc/net/rpc/nfsd.fh/flush",
+	"/proc/net/rpc/nfsd.export/flush",
+	NULL,
+};
+
+/**
+ * Write time into one file
+ *
+ * @param pathname NUL-terminated C string containing POSIX pathname of file to write
+ * @param flushtime NUL-terminated C string containing current time in seconds since the Epoch
+ * @return a FedFsStatus code
+ */
+static FedFsStatus
+junction_write_time(const char *pathname, const char *flushtime)
+{
+	FedFsStatus retval;
+	ssize_t len;
+	int fd;
+
+	fd = open(pathname, O_RDWR);
+	if (fd == -1) {
+		xlog(D_GENERAL, "%s: Failed to open %s: %m",
+			__func__, pathname);
+		/* If the proc files don't exist, no server
+		 * is running on this system */
+		return FEDFS_ERR_NO_CACHE_UPDATE;
+	}
+
+	len = write(fd, flushtime, strlen(flushtime));
+	if (len != (ssize_t)strlen(flushtime)) {
+		xlog(D_GENERAL, "%s: Failed to write %s: %m",
+			__func__, pathname);
+		/* If the proc files exist but the update failed,
+		 * we don't know the state of the cache */
+		retval = FEDFS_ERR_UNKNOWN_CACHE;
+	} else
+		/* Cache flush succeeded */
+		retval = FEDFS_OK;
+	
+	(void)close(fd);
+	return retval;
+}
+
+/**
+ * Flush the kernel NFSD's exports cache
+ *
+ * @return a FedFsStatus code
+ */
+FedFsStatus
+junction_flush_exports_cache(void)
+{
+	FedFsStatus retval;
+	char flushtime[20];
+	unsigned int i;
+	time_t now;
+
+	xlog(D_CALL, "%s: Flushing NFSD caches...", __func__);
+
+	now = time(NULL);
+	if (now == -1) {
+		xlog(D_GENERAL, "%s: time(3) failed", __func__);
+		return FEDFS_ERR_SVRFAULT;
+	}
+	snprintf(flushtime, sizeof(flushtime), "%ld\n", now);
+
+	for (i = 0; junction_proc_files[i] != NULL; i++) {
+		retval = junction_write_time(junction_proc_files[i], flushtime);
+		if (retval != FEDFS_OK)
+			return retval;
+	}
+	return FEDFS_OK;
+}