svn commit: r243739 - stable/9/usr.sbin/mountd

[Rick Macklem]

Author: rmacklem
Date: Sat Dec  1 01:11:59 2012
New Revision: 243739
URL: http://svnweb.freebsd.org/changeset/base/243739

Log:
  MFC: r241568
  Add a new '-S' option to mountd, which tells it to suspend
  execution of the nfsd threads while it is reloading the exports.
  This avoids clients from getting intermittent access errors
  when the exports are being reloaded non-atomically.
  It is not an ideal solution, since requests will back up while
  the nfsd threads are suspended. Also, when this option is used,
  if mountd crashes while reloading exports, mountd will have to
  be restarted to get the nfsd threads to resume execution.
  This has been tested by Vincent Hoffman (vince at unsane.co.uk)
  and John Hickey (jh at deterlab.net).
  The nfse patch offers a more comprehensive solution for this issue.

Modified:
  stable/9/usr.sbin/mountd/mountd.c
Directory Properties:
  stable/9/usr.sbin/mountd/   (props changed)

Modified: stable/9/usr.sbin/mountd/mountd.c
==============================================================================
--- stable/9/usr.sbin/mountd/mountd.c	Sat Dec  1 01:07:51 2012	(r243738)
+++ stable/9/usr.sbin/mountd/mountd.c	Sat Dec  1 01:11:59 2012	(r243739)
@@ -246,6 +246,7 @@ static int	mallocd_svcport = 0;
 static int	*sock_fd;
 static int	sock_fdcnt;
 static int	sock_fdpos;
+static int	suspend_nfsd = 0;
 
 int opt_flags;
 static int have_v6 = 1;
@@ -311,7 +312,7 @@ main(int argc, char **argv)
 	else
 		close(s);
 
-	while ((c = getopt(argc, argv, "2deh:lnop:r")) != -1)
+	while ((c = getopt(argc, argv, "2deh:lnop:rS")) != -1)
 		switch (c) {
 		case '2':
 			force_v2 = 1;
@@ -363,6 +364,9 @@ main(int argc, char **argv)
 				out_of_mem();
 			}
 			break;
+		case 'S':
+			suspend_nfsd = 1;
+			break;
 		default:
 			usage();
 		};
@@ -921,7 +925,7 @@ usage(void)
 {
 	fprintf(stderr,
 		"usage: mountd [-2] [-d] [-e] [-l] [-n] [-p <port>] [-r] "
-		"[-h <bindip>] [export_file ...]\n");
+		"[-S] [-h <bindip>] [export_file ...]\n");
 	exit(1);
 }
 
@@ -1660,6 +1664,8 @@ get_exportlist(void)
 	int done;
 	struct nfsex_args eargs;
 
+	if (suspend_nfsd != 0)
+		(void)nfssvc(NFSSVC_SUSPENDNFSD, NULL);
 	v4root_dirpath[0] = '\0';
 	bzero(&export, sizeof(export));
 	export.ex_flags = MNT_DELEXPORT;
@@ -1790,6 +1796,9 @@ get_exportlist(void)
 	 */
 	if (run_v4server > 0 && has_publicfh == 0)
 		(void) nfssvc(NFSSVC_NOPUBLICFH, NULL);
+
+	/* Resume the nfsd. If they weren't suspended, this is harmless. */
+	(void)nfssvc(NFSSVC_RESUMENFSD, NULL);
 }
 
 /*