From 42d6c4b8c31ae5ea775ca7f685525cf0cb328277 Mon Sep 17 00:00:00 2001
From: Robert Ricci <ricci@cs.utah.edu>
Date: Wed, 14 Aug 2002 00:46:30 +0000
Subject: [PATCH] Change locking in exports_setup in the same way I changed it
in named_setup.
---
tbsetup/exports_setup.in | 57 ++++++++++++++++++++++++++++++++++------
1 file changed, 49 insertions(+), 8 deletions(-)
diff --git a/tbsetup/exports_setup.in b/tbsetup/exports_setup.in
index 9e715fcebf..2ac0b11295 100644
--- a/tbsetup/exports_setup.in
+++ b/tbsetup/exports_setup.in
@@ -76,17 +76,58 @@ use libtestbed;
# a dummy file in /var/tmp, opened for writing and flock'ed.
#
if (!$TESTMODE) {
- open(LOCK, ">>$lockfile") || fatal("Couldn't open $lockfile\n");
- $count = 0;
- while (flock(LOCK, LOCK_EX|LOCK_NB) == 0) {
- print "Another /etc/exports update in progress. Waiting a moment ...\n";
- if ($count++ > 20) {
- fatal("Could not get the lock after a long time!\n");
+ open(LOCK, ">>$lockfile") || fatal("Couldn't open $lockfile\n");
+ $count = 0;
+ if (flock(LOCK, LOCK_EX|LOCK_NB) == 0) {
+ #
+ # If we don't get it the first time, we wait for:
+ # 1) The lock to become free, in which case we do our thing
+ # 2) The time on the lock to change, in which case we wait for that process
+ # to finish
+ #
+ my $oldlocktime = (stat(LOCK))[9];
+ my $gotlock = 0;
+ while (1) {
+ print "Another exports update in progress, waiting for it to finish\n";
+ if (flock(LOCK, LOCK_EX|LOCK_NB) != 0) {
+ # OK, got the lock, we can do what we're supposed to
+ $gotlock = 1;
+ last;
+ }
+ $locktime = (stat(LOCK))[9];
+ if ($locktime != $oldlocktime) {
+ $oldlocktime = $locktime;
+ last;
+ }
+ if ($count++ > 20) {
+ fatal("Could not get the lock after a long time!\n");
+ }
+ sleep(1);
+ }
+
+ $count = 0;
+ #
+ # If we didn't get the lock, wait for the processes that did to finish
+ #
+ if (!$gotlock) {
+ while (((stat(LOCK))[9] != $oldlocktime) &&
+ (flock(LOCK, LOCK_EX|LOCK_NB) == 0)) {
+ if ($count++ > 20) {
+ fatal("Could not get the lock after a long time!\n");
+ }
+ sleep(1);
+ }
+ exit(0);
+ }
}
- sleep(1);
- }
}
+#
+# Perl-style touch(1)
+#
+my $now = time;
+utime $now, $now, $lockfile;
+
#
# We stick the new map entries into the tail file. First zero it out.
#
--
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