autofs-5.0.4 - force unlink umount at startup

From: Ian Kent <raven@themaw.net>

Version 5.0.3 autofs would unlink existing mounts at startup. This

functioned OK most of the time but caused processes whose working

directory was within unlinked automounted directories to not get a

correct pwd reported by the system.

There can be situations where the unlink umounting is desirable, such

as when the daemon is forceably killed and we want to get rid of any

existing mounts at startup. This change provides a way to force this

old behavior by passing the "--force" option to the daemon. This can

also be done by using the "forcestart" and "forcerestart" actions to

the init script.

Note that the old behavior will always be used if the kernel does not

include the iotcl re-implementation which provides the ability to

re-connect to existing mounts.

---

 CHANGELOG             |    2 ++

 daemon/automount.c    |   14 +++++++++++++-

 daemon/direct.c       |    2 +-

 daemon/indirect.c     |    2 +-

 include/automount.h   |    3 +++

 man/automount.8       |   13 +++++++++++++

 redhat/autofs.init.in |   10 +++++++++-

 samples/rc.autofs.in  |   10 +++++++++-

 8 files changed, 51 insertions(+), 5 deletions(-)

diff --git a/CHANGELOG b/CHANGELOG

index 7dee674..d4dd70b 100644

--- a/CHANGELOG

+++ b/CHANGELOG

@@ -12,6 +12,8 @@

 - fix hosts map use after free.

 - fix uri list locking (again).

 - check for stale SASL credentials upon connect fail.

+- add "forcestart" and "forcerestart" init script options to allow

+  use of 5.0.3 strartup behavior if required.

 4/11/2008 autofs-5.0.4

 -----------------------

diff --git a/daemon/automount.c b/daemon/automount.c

index f04273f..e20e7c9 100644

--- a/daemon/automount.c

+++ b/daemon/automount.c

@@ -57,6 +57,7 @@ static char *pid_file = NULL;		/* File in which to keep pid */

 unsigned int global_random_selection;	/* use random policy when selecting

 					 * which multi-mount host to mount */

 long global_negative_timeout = -1;

+int do_force_unlink = 0;		/* Forceably unlink mount tree at startup */

 static int start_pipefd[2];

 static int st_stat = 0;

@@ -1798,6 +1799,7 @@ int main(int argc, char *argv[])

 		{"version", 0, 0, 'V'},

 		{"set-log-priority", 1, 0, 'l'},

 		{"dont-check-daemon", 0, 0, 'C'},

+		{"force", 0, 0, 'F'},

 		{0, 0, 0, 0}

 	};

@@ -1819,7 +1821,7 @@ int main(int argc, char *argv[])

 	daemon_check = 1;

 	opterr = 0;

-	while ((opt = getopt_long(argc, argv, "+hp:t:vdD:fVrO:l:n:C", long_options, NULL)) != EOF) {

+	while ((opt = getopt_long(argc, argv, "+hp:t:vdD:fVrO:l:n:CF", long_options, NULL)) != EOF) {

 		switch (opt) {

 		case 'h':

 			usage();

@@ -1892,6 +1894,10 @@ int main(int argc, char *argv[])

 			daemon_check = 0;

 			break;

+		case 'F':

+			do_force_unlink = 1;

+			break;

+

 		case '?':

 		case ':':

 			printf("%s: Ambiguous or unknown options\n", program);

@@ -2066,6 +2072,12 @@ int main(int argc, char *argv[])

 		exit(3);

 	}

+	/*

+	 * Mmm ... reset force unlink umount so we don't also do this

+	 * in future when we receive a HUP signal.

+	 */

+	do_force_unlink = 0;

+

 	res = write(start_pipefd[1], pst_stat, sizeof(*pst_stat));

 	close(start_pipefd[1]);

diff --git a/daemon/direct.c b/daemon/direct.c

index d9dda3d..2d979f1 100644

--- a/daemon/direct.c

+++ b/daemon/direct.c

@@ -335,7 +335,7 @@ int do_mount_autofs_direct(struct autofs_point *ap, struct mnt_list *mnts, struc

 	/* Calculate the timeouts */

 	ap->exp_runfreq = (timeout + CHECK_RATIO - 1) / CHECK_RATIO;

-	if (ops->version) {

+	if (ops->version && !do_force_unlink) {

 		ap->flags |= MOUNT_FLAG_REMOUNT;

 		ret = try_remount(ap, me, t_direct);

 		ap->flags &= ~MOUNT_FLAG_REMOUNT;

diff --git a/daemon/indirect.c b/daemon/indirect.c

index 0721707..2ccbc53 100644

--- a/daemon/indirect.c

+++ b/daemon/indirect.c

@@ -97,7 +97,7 @@ static int do_mount_autofs_indirect(struct autofs_point *ap, const char *root)

 	ap->exp_runfreq = (timeout + CHECK_RATIO - 1) / CHECK_RATIO;

-	if (ops->version) {

+	if (ops->version && !do_force_unlink) {

 		ap->flags |= MOUNT_FLAG_REMOUNT;

 		ret = try_remount(ap, NULL, t_indirect);

 		ap->flags &= ~MOUNT_FLAG_REMOUNT;

diff --git a/include/automount.h b/include/automount.h

index 46cb6c6..1f14d5b 100644

--- a/include/automount.h

+++ b/include/automount.h

@@ -428,6 +428,9 @@ struct autofs_point {

 	struct list_head submounts;	/* List of child submounts */

 };

+/* Foreably unlink existing mounts at startup. */

+extern int do_force_unlink;

+

 /* Standard functions used by daemon or modules */

 #define	MOUNT_OFFSET_OK		0

diff --git a/man/automount.8 b/man/automount.8

index d9285bf..9fcaaf4 100644

--- a/man/automount.8

+++ b/man/automount.8

@@ -84,6 +84,11 @@ path name as specified in the master map.

 .TP

 .I "\-C, \-\-dont-check-daemon"

 Don't check if the daemon is currently running (see NOTES).

+.TP

+.I "\-F, \-\-force"

+Force an unlink umount of existing mounts under autofs managed mount points

+during startup. This can cause problems for processes with working directories

+within these mounts (see NOTES).

 .SH ARGUMENTS

 \fBautomount\fP takes one optional argument, the name of the master map to

 use.

@@ -132,6 +137,14 @@ for certain types of automount maps. The mounts of the seperate daemons

 might interfere with one another. The implications of running multiple

 daemon instances needs to be checked and tested before we can say this

 is supported.

+.P

+If the option to force an unlink of mounts at startup is used then processes

+whose working directory is within unlinked automounted directories will not

+get the correct pwd from the system. This is because, after the mount is

+unlinked from the mount tree, anything that needs to walk back up the mount

+tree to construct a path, such as getcwd(2) and the proc filesystem

+/proc/<pid>/cwd, cannot work because the point from which the path is

+constructed has been detached from the mount tree.

 .SH "SEE ALSO"

 .BR autofs (5),

 .BR autofs (8),

diff --git a/redhat/autofs.init.in b/redhat/autofs.init.in

index 65c786e..471667e 100644

--- a/redhat/autofs.init.in

+++ b/redhat/autofs.init.in

@@ -137,6 +137,10 @@ case "$1" in

 	start)

 		start

 		;;

+	forcestart)

+		OPTIONS="$OPTIONS --force"

+		start

+		;;

 	stop)

 		stop

 		;;

@@ -146,6 +150,10 @@ case "$1" in

 	restart)

 		restart

 		;;

+	forcerestart)

+		OPTIONS="$OPTIONS --force"

+		restart

+		;;

 	reload)

 		reload

 		;;

@@ -155,7 +163,7 @@ case "$1" in

 		fi

 		;;

 	*)

-		echo $"Usage: $0 {start|stop|status|restart|reload|condrestart}"

+		echo $"Usage: $0 {start|forcestart|stop|status|restart|orcerestart|reload|condrestart}"

 		exit 1;

 		;;

 esac

diff --git a/samples/rc.autofs.in b/samples/rc.autofs.in

index 51f5b02..2877fe2 100644

--- a/samples/rc.autofs.in

+++ b/samples/rc.autofs.in

@@ -117,17 +117,25 @@ case "$1" in

 	start)

 		start

 		;;

+	forcestart)

+		OPTIONS="$OPTIONS --force"

+		start

+		;;

 	stop)

 		stop

 		;;

 	restart)

 		restart

 		;;

+	forcerestart)

+		OPTIONS="$OPTIONS --force"

+		restart

+		;;

 	reload)

 		reload

 		;;

 	*)

-		echo $"Usage: $0 {start|stop|restart|reload}"

+		echo $"Usage: $0 {start|forcestart|stop|restart|forcerestart|reload}"

 		exit 1;

 		;;

 esac