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ocfs2: use 64bit variables to track heartbeat time

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o2hb_elapsed_msecs computes the time taken for a disk heartbeat.
'struct timeval' variables are used to store start and end times.  On
32-bit systems, the 'tv_sec' component of 'struct timeval' will overflow
in year 2038 and beyond.

This patch solves the overflow with the following:

1. Replace o2hb_elapsed_msecs using 'ktime_t' values to measure start
   and end time, and built-in function 'ktime_ms_delta' to compute the
   elapsed time.  ktime_get_real() is used since the code prints out the
   wallclock time.

2. Changes format string to print time as a single 64-bit nanoseconds
   value ("%lld") instead of seconds and microseconds.  This simplifies
   the code since converting ktime_t to that format would need expensive
   computation.  However, the debug log string is less readable than the
   previous format.

Signed-off-by: Tina Ruchandani <ruchandani.tina@gmail.com>
Suggested by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Tina Ruchandani 2015-09-04 15:44:43 -07:00 committed by Linus Torvalds
parent ad69482122
commit 40476b8294
1 changed files with 9 additions and 40 deletions
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49
fs/ocfs2/cluster/heartbeat.c
View File

@ -36,7 +36,7 @@
#include <linux/debugfs.h>
#include <linux/slab.h>
#include <linux/bitmap.h>
#include <linux/ktime.h>
#include "heartbeat.h"
#include "tcp.h"
#include "nodemanager.h"
@ -1060,37 +1060,6 @@ bail:
return ret;
}
/* Subtract b from a, storing the result in a. a *must* have a larger
* value than b. */
static void o2hb_tv_subtract(struct timeval *a,
struct timeval *b)
{
/* just return 0 when a is after b */
if (a->tv_sec < b->tv_sec ||
(a->tv_sec == b->tv_sec && a->tv_usec < b->tv_usec)) {
a->tv_sec = 0;
a->tv_usec = 0;
return;
}
a->tv_sec -= b->tv_sec;
a->tv_usec -= b->tv_usec;
while ( a->tv_usec < 0 ) {
a->tv_sec--;
a->tv_usec += 1000000;
}
}
static unsigned int o2hb_elapsed_msecs(struct timeval *start,
struct timeval *end)
{
struct timeval res = *end;
o2hb_tv_subtract(&res, start);
return res.tv_sec * 1000 + res.tv_usec / 1000;
}
/*
* we ride the region ref that the region dir holds. before the region
* dir is removed and drops it ref it will wait to tear down this
@ -1101,7 +1070,7 @@ static int o2hb_thread(void *data)
int i, ret;
struct o2hb_region *reg = data;
struct o2hb_bio_wait_ctxt write_wc;
struct timeval before_hb, after_hb;
ktime_t before_hb, after_hb;
unsigned int elapsed_msec;
mlog(ML_HEARTBEAT|ML_KTHREAD, "hb thread running\n");
@ -1118,18 +1087,18 @@ static int o2hb_thread(void *data)
* hr_timeout_ms between disk writes. On busy systems
* this should result in a heartbeat which is less
* likely to time itself out. */
do_gettimeofday(&before_hb);
before_hb = ktime_get_real();
ret = o2hb_do_disk_heartbeat(reg);
do_gettimeofday(&after_hb);
elapsed_msec = o2hb_elapsed_msecs(&before_hb, &after_hb);
after_hb = ktime_get_real();
elapsed_msec = (unsigned int)
ktime_ms_delta(after_hb, before_hb);
mlog(ML_HEARTBEAT,
"start = %lu.%lu, end = %lu.%lu, msec = %u, ret = %d\n",
before_hb.tv_sec, (unsigned long) before_hb.tv_usec,
after_hb.tv_sec, (unsigned long) after_hb.tv_usec,
elapsed_msec, ret);
"start = %lld, end = %lld, msec = %u, ret = %d\n",
before_hb.tv64, after_hb.tv64, elapsed_msec, ret);
if (!kthread_should_stop() &&
elapsed_msec < reg->hr_timeout_ms) {