monotonic time for mount.cifs timeouts

* monotonic time for mount.cifs timeouts
@ 2010-08-24 16:16 Björn JACKE
       [not found] ` <E1OnwAo-008Rzd-Bd-dqLtpHMqGvUyWpdLl23E4A@public.gmane.org>
  0 siblings, 1 reply; 8+ messages in thread
From: Björn JACKE @ 2010-08-24 16:16 UTC (permalink / raw)
  To: linux-cifs-u79uwXL29TY76Z2rM5mHXA


[-- Attachment #1.1: Type: text/plain, Size: 220 bytes --]

Hi,

attached are patches to spot the clock_gettime function and to use that and the
monotonic clock for timeout handling if possible.

If there are no objections, can you please apply them, Jeff?

Thanks
Björn

[-- Attachment #1.2: 0001-autoconf-add-checks-for-clock_gettime.patch --]
[-- Type: text/x-patch, Size: 1199 bytes --]

From 250d5b5df23d93ebed66a4c39bccf3a3614c54ad Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Jacke?= <bj-3ekOc4rQMZmzQB+pC5nmwQ@public.gmane.org>
Date: Tue, 24 Aug 2010 09:39:32 +0200
Subject: [PATCH 1/2] autoconf: add checks for clock_gettime

---
 configure.ac |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/configure.ac b/configure.ac
index c7d420d..7f82cd6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -110,6 +110,16 @@ AC_FUNC_STRNLEN
 # check for required functions
 AC_CHECK_FUNCS([alarm atexit endpwent getmntent getpass gettimeofday inet_ntop memset realpath setenv strchr strcmp strdup strerror strncasecmp strndup strpbrk strrchr strstr strtol strtoul tolower uname], , [AC_MSG_ERROR([necessary functions(s) not found])])
 
+AC_CHECK_FUNCS(clock_gettime, [], [
+  AC_CHECK_LIB(rt, clock_gettime, [
+      AC_DEFINE(HAVE_CLOCK_GETTIME, 1)
+	AC_DEFINE(HAVE_CLOCK_GETTIME,1,
+		[Whether the clock_gettime func is there])
+      LIBS="$LIBS -lrt"
+        ])
+  ])
+
+
 # ugly, but I'm not sure how to check for functions in a library that's not in $LIBS
 cu_saved_libs=$LIBS
 LIBS="$LIBS $KRB5_LDADD"
-- 
1.7.1


[-- Attachment #1.3: 0002-mount.cifs-use-monotonic-time-for-timeouts.patch --]
[-- Type: text/x-patch, Size: 2138 bytes --]

From 4e8d243b9b0a5eb7bf4619c4cddbd9d3a8f4eb2d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Jacke?= <bj-3ekOc4rQMZmzQB+pC5nmwQ@public.gmane.org>
Date: Tue, 24 Aug 2010 09:41:01 +0200
Subject: [PATCH 2/2] mount.cifs: use monotonic time for timeouts

this is especially important during the boot process, where the clock is often
being set initially and clock jumps are more common.
---
 mtab.c |   23 ++++++++++++++++++++---
 1 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/mtab.c b/mtab.c
index de1aabd..64e7250 100644
--- a/mtab.c
+++ b/mtab.c
@@ -39,6 +39,7 @@
 #include <stdlib.h>
 #include <signal.h>
 #include "mount.h"
+#include "config.h"
 
 
 /* Updating mtab ----------------------------------------------*/
@@ -60,6 +61,22 @@ setlkw_timeout (int sig __attribute__((unused))) {
      /* nothing, fcntl will fail anyway */
 }
 
+/* use monotonic time for timeouts */
+struct timeval
+mono_time(void) {
+	struct timeval ret;
+#if defined(HAVE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC)
+	struct timespec ts;
+	if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0) {
+		ret.tv_sec = ts.tv_sec;
+		ret.tv_usec = ts.tv_nsec/1000;
+		return ret;
+	}
+#endif
+	gettimeofday(&ret,NULL);
+	return ret;
+}
+
 /* Remove lock file.  */
 void
 unlock_mtab (void) {
@@ -150,7 +167,7 @@ lock_mtab (void) {
 	}
 	close(i);
 
-	gettimeofday(&maxtime, NULL);
+	maxtime = mono_time();
 	maxtime.tv_sec += MOUNTLOCK_MAXTIME;
 
 	waittime.tv_sec = 0;
@@ -177,7 +194,7 @@ lock_mtab (void) {
 
 		if (lockfile_fd < 0) {
 			/* Strange... Maybe the file was just deleted? */
-			gettimeofday(&now, NULL);
+			now = mono_time();
 			if (errno == ENOENT && now.tv_sec < maxtime.tv_sec) {
 				we_created_lockfile = 0;
 				continue;
@@ -199,7 +216,7 @@ lock_mtab (void) {
 			(void) unlink(linktargetfile);
 		} else {
 			/* Someone else made the link. Wait. */
-			gettimeofday(&now, NULL);
+			now = mono_time();
 			if (now.tv_sec < maxtime.tv_sec) {
 				alarm(maxtime.tv_sec - now.tv_sec);
 				if (fcntl (lockfile_fd, F_SETLKW, &flock) == -1) {
-- 
1.7.1


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