Function mmp_thread

freebsd/contrib/openzfs/module/zfs/mmp.c:539–698

}

static void
mmp_thread(void *arg)
{
	spa_t *spa = (spa_t *)arg;
	mmp_thread_t *mmp = &spa->spa_mmp;
	boolean_t suspended = spa_suspended(spa);
	boolean_t multihost = spa_multihost(spa);
	uint64_t mmp_interval = MSEC2NSEC(MMP_INTERVAL_OK(
	    zfs_multihost_interval));
	uint32_t mmp_fail_intervals = MMP_FAIL_INTVS_OK(
	    zfs_multihost_fail_intervals);
	hrtime_t mmp_fail_ns = mmp_fail_intervals * mmp_interval;
	boolean_t last_spa_suspended = suspended;
	boolean_t last_spa_multihost = multihost;
	uint64_t last_mmp_interval = mmp_interval;
	uint32_t last_mmp_fail_intervals = mmp_fail_intervals;
	hrtime_t last_mmp_fail_ns = mmp_fail_ns;
	callb_cpr_t cpr;
	int skip_wait = 0;

	mmp_thread_enter(mmp, &cpr);

	/*
	 * There have been no MMP writes yet.  Setting mmp_last_write here gives
	 * us one mmp_fail_ns period, which is consistent with the activity
	 * check duration, to try to land an MMP write before MMP suspends the
	 * pool (if so configured).
	 */

	mutex_enter(&mmp->mmp_io_lock);
	mmp->mmp_last_write = gethrtime();
	mmp->mmp_delay = MSEC2NSEC(MMP_INTERVAL_OK(zfs_multihost_interval));
	mutex_exit(&mmp->mmp_io_lock);

	while (!mmp->mmp_thread_exiting) {
		hrtime_t next_time = gethrtime() +
		    MSEC2NSEC(MMP_DEFAULT_INTERVAL);
		int leaves = MAX(vdev_count_leaves(spa), 1);

		/* Detect changes in tunables or state */

		last_spa_suspended = suspended;
		last_spa_multihost = multihost;
		suspended = spa_suspended(spa);
		multihost = spa_multihost(spa);

		last_mmp_interval = mmp_interval;
		last_mmp_fail_intervals = mmp_fail_intervals;
		last_mmp_fail_ns = mmp_fail_ns;
		mmp_interval = MSEC2NSEC(MMP_INTERVAL_OK(
		    zfs_multihost_interval));
		mmp_fail_intervals = MMP_FAIL_INTVS_OK(
		    zfs_multihost_fail_intervals);

		/* Smooth so pool is not suspended when reducing tunables */
		if (mmp_fail_intervals * mmp_interval < mmp_fail_ns) {
			mmp_fail_ns = (mmp_fail_ns * 31 +
			    mmp_fail_intervals * mmp_interval) / 32;