/*ARGSUSED*/
int
zfs_sync(struct super_block *sb, int wait, cred_t *cr)
{
zfs_sb_t *zsb = sb->s_fs_info;
/*
* Data integrity is job one. We don't want a compromised kernel
* writing to the storage pool, so we never sync during panic.
*/
if (unlikely(oops_in_progress))
return (0);
/*
* Semantically, the only requirement is that the sync be initiated.
* The DMU syncs out txgs frequently, so there's nothing to do.
*/
if (!wait)
return (0);
if (zsb != NULL) {
/*
* Sync a specific filesystem.
*/
dsl_pool_t *dp;
ZFS_ENTER(zsb);
dp = dmu_objset_pool(zsb->z_os);
/*
* If the system is shutting down, then skip any
* filesystems which may exist on a suspended pool.
*/
if (spa_suspended(dp->dp_spa)) {
ZFS_EXIT(zsb);
return (0);
}
if (zsb->z_log != NULL)
zil_commit(zsb->z_log, 0);
ZFS_EXIT(zsb);
} else {
/*
* Sync all ZFS filesystems. This is what happens when you
* run sync(1M). Unlike other filesystems, ZFS honors the
* request by waiting for all pools to commit all dirty data.
*/
spa_sync_allpools();
}
return (0);
}
static void
mmp_thread(void *arg)
{
spa_t *spa = (spa_t *)arg;
mmp_thread_t *mmp = &spa->spa_mmp;
boolean_t last_spa_suspended = spa_suspended(spa);
boolean_t last_spa_multihost = spa_multihost(spa);
callb_cpr_t cpr;
hrtime_t max_fail_ns = zfs_multihost_fail_intervals *
MSEC2NSEC(MAX(zfs_multihost_interval, MMP_MIN_INTERVAL));
mmp_thread_enter(mmp, &cpr);
/*
* The mmp_write_done() function calculates mmp_delay based on the
* prior value of mmp_delay and the elapsed time since the last write.
* For the first mmp write, there is no "last write", so we start
* with fake, but reasonable, default non-zero values.
*/
mmp->mmp_delay = MSEC2NSEC(MAX(zfs_multihost_interval,
MMP_MIN_INTERVAL)) / MAX(vdev_count_leaves(spa), 1);
mmp->mmp_last_write = gethrtime() - mmp->mmp_delay;
while (!mmp->mmp_thread_exiting) {
uint64_t mmp_fail_intervals = zfs_multihost_fail_intervals;
uint64_t mmp_interval = MSEC2NSEC(
MAX(zfs_multihost_interval, MMP_MIN_INTERVAL));
boolean_t suspended = spa_suspended(spa);
boolean_t multihost = spa_multihost(spa);
hrtime_t start, next_time;
start = gethrtime();
if (multihost) {
next_time = start + mmp_interval /
MAX(vdev_count_leaves(spa), 1);
} else {
next_time = start + MSEC2NSEC(MMP_DEFAULT_INTERVAL);
}
/*
* When MMP goes off => on, or spa goes suspended =>
* !suspended, we know no writes occurred recently. We
* update mmp_last_write to give us some time to try.
*/
if ((!last_spa_multihost && multihost) ||
(last_spa_suspended && !suspended)) {
mutex_enter(&mmp->mmp_io_lock);
mmp->mmp_last_write = gethrtime();
mutex_exit(&mmp->mmp_io_lock);
} else if (last_spa_multihost && !multihost) {
mutex_enter(&mmp->mmp_io_lock);
mmp->mmp_delay = 0;
mutex_exit(&mmp->mmp_io_lock);
}
last_spa_multihost = multihost;
last_spa_suspended = suspended;
/*
* Smooth max_fail_ns when its factors are decreased, because
* making (max_fail_ns < mmp_interval) results in the pool being
* immediately suspended before writes can occur at the new
* higher frequency.
*/
if ((mmp_interval * mmp_fail_intervals) < max_fail_ns) {
max_fail_ns = ((31 * max_fail_ns) + (mmp_interval *
mmp_fail_intervals)) / 32;
} else {
max_fail_ns = mmp_interval * mmp_fail_intervals;
}
/*
* Suspend the pool if no MMP write has succeeded in over
* mmp_interval * mmp_fail_intervals nanoseconds.
*/
if (!suspended && mmp_fail_intervals && multihost &&
(start - mmp->mmp_last_write) > max_fail_ns) {
zio_suspend(spa, NULL);
}
if (multihost)
mmp_write_uberblock(spa);
CALLB_CPR_SAFE_BEGIN(&cpr);
(void) cv_timedwait_sig(&mmp->mmp_thread_cv,
&mmp->mmp_thread_lock, ddi_get_lbolt() +
((next_time - gethrtime()) / (NANOSEC / hz)));
CALLB_CPR_SAFE_END(&cpr, &mmp->mmp_thread_lock);
}
/* Outstanding writes are allowed to complete. */
if (mmp->mmp_zio_root)
zio_wait(mmp->mmp_zio_root);
mmp->mmp_zio_root = NULL;
mmp_thread_exit(mmp, &mmp->mmp_thread, &cpr);
}
