/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Portions Copyright 2011 Martin Matuska <mm@FreeBSD.org>
* Copyright (c) 2012, 2017 by Delphix. All rights reserved.
*/
#include <sys/zfs_context.h>
#include <sys/txg_impl.h>
#include <sys/dmu_impl.h>
#include <sys/dmu_tx.h>
#include <sys/dsl_pool.h>
#include <sys/dsl_scan.h>
#include <sys/zil.h>
#include <sys/callb.h>
/*
* ZFS Transaction Groups
* ----------------------
*
* ZFS transaction groups are, as the name implies, groups of transactions
* that act on persistent state. ZFS asserts consistency at the granularity of
* these transaction groups. Each successive transaction group (txg) is
* assigned a 64-bit consecutive identifier. There are three active
* transaction group states: open, quiescing, or syncing. At any given time,
* there may be an active txg associated with each state; each active txg may
* either be processing, or blocked waiting to enter the next state. There may
* be up to three active txgs, and there is always a txg in the open state
* (though it may be blocked waiting to enter the quiescing state). In broad
* strokes, transactions -- operations that change in-memory structures -- are
* accepted into the txg in the open state, and are completed while the txg is
* in the open or quiescing states. The accumulated changes are written to
* disk in the syncing state.
*
* Open
*
* When a new txg becomes active, it first enters the open state. New
* transactions -- updates to in-memory structures -- are assigned to the
* currently open txg. There is always a txg in the open state so that ZFS can
* accept new changes (though the txg may refuse new changes if it has hit
* some limit). ZFS advances the open txg to the next state for a variety of
* reasons such as it hitting a time or size threshold, or the execution of an
* administrative action that must be completed in the syncing state.
*
* Quiescing
*
* After a txg exits the open state, it enters the quiescing state. The
* quiescing state is intended to provide a buffer between accepting new
* transactions in the open state and writing them out to stable storage in
* the syncing state. While quiescing, transactions can continue their
* operation without delaying either of the other states. Typically, a txg is
* in the quiescing state very briefly since the operations are bounded by
* software latencies rather than, say, slower I/O latencies. After all
* transactions complete, the txg is ready to enter the next state.
*
* Syncing
*
* In the syncing state, the in-memory state built up during the open and (to
* a lesser degree) the quiescing states is written to stable storage. The
* process of writing out modified data can, in turn modify more data. For
* example when we write new blocks, we need to allocate space for them; those
* allocations modify metadata (space maps)... which themselves must be
* written to stable storage. During the sync state, ZFS iterates, writing out
* data until it converges and all in-memory changes have been written out.
* The first such pass is the largest as it encompasses all the modified user
* data (as opposed to filesystem metadata). Subsequent passes typically have
* far less data to write as they consist exclusively of filesystem metadata.
*
* To ensure convergence, after a certain number of passes ZFS begins
* overwriting locations on stable storage that had been allocated earlier in
* the syncing state (and subsequently freed). ZFS usually allocates new
* blocks to optimize for large, continuous, writes. For the syncing state to
* converge however it must complete a pass where no new blocks are allocated
* since each allocation requires a modification of persistent metadata.
* Further, to hasten convergence, after a prescribed number of passes, ZFS
* also defers frees, and stops compressing.
*
* In addition to writing out user data, we must also execute synctasks during
* the syncing context. A synctask is the mechanism by which some
* administrative activities work such as creating and destroying snapshots or
* datasets. Note that when a synctask is initiated it enters the open txg,
* and ZFS then pushes that txg as quickly as possible to completion of the
* syncing state in order to reduce the latency of the administrative
* activity. To complete the syncing state, ZFS writes out a new uberblock,
* the root of the tree of blocks that comprise all state stored on the ZFS
* pool. Finally, if there is a quiesced txg waiting, we signal that it can
* now transition to the syncing state.
*/
static void txg_sync_thread(void *arg);
static void txg_quiesce_thread(void *arg);
int zfs_txg_timeout = 5; /* max seconds worth of delta per txg */
SYSCTL_DECL(_vfs_zfs);
SYSCTL_NODE(_vfs_zfs, OID_AUTO, txg, CTLFLAG_RW, 0, "ZFS TXG");
SYSCTL_INT(_vfs_zfs_txg, OID_AUTO, timeout, CTLFLAG_RWTUN, &zfs_txg_timeout, 0,
"Maximum seconds worth of delta per txg");
/*
* Prepare the txg subsystem.
*/
void
txg_init(dsl_pool_t *dp, uint64_t txg)
{
tx_state_t *tx = &dp->dp_tx;
int c;
bzero(tx, sizeof (tx_state_t));
tx->tx_cpu = kmem_zalloc(max_ncpus * sizeof (tx_cpu_t), KM_SLEEP);
for (c = 0; c < max_ncpus; c++) {
int i;
mutex_init(&tx->tx_cpu[c].tc_lock, NULL, MUTEX_DEFAULT, NULL);
mutex_init(&tx->tx_cpu[c].tc_open_lock, NULL, MUTEX_DEFAULT,
NULL);
for (i = 0; i < TXG_SIZE; i++) {
cv_init(&tx->tx_cpu[c].tc_cv[i], NULL, CV_DEFAULT,
NULL);
list_create(&tx->tx_cpu[c].tc_callbacks[i],
sizeof (dmu_tx_callback_t),
offsetof(dmu_tx_callback_t, dcb_node));
}
}
mutex_init(&tx->tx_sync_lock, NULL, MUTEX_DEFAULT, NULL);
cv_init(&tx->tx_sync_more_cv, NULL, CV_DEFAULT, NULL);
cv_init(&tx->tx_sync_done_cv, NULL, CV_DEFAULT, NULL);
cv_init(&tx->tx_quiesce_more_cv, NULL, CV_DEFAULT, NULL);
cv_init(&tx->tx_quiesce_done_cv, NULL, CV_DEFAULT, NULL);
cv_init(&tx->tx_exit_cv, NULL, CV_DEFAULT, NULL);
tx->tx_open_txg = txg;
}
/*
* Close down the txg subsystem.
*/
void
txg_fini(dsl_pool_t *dp)
{
tx_state_t *tx = &dp->dp_tx;
int c;
ASSERT0(tx->tx_threads);
mutex_destroy(&tx->tx_sync_lock);
cv_destroy(&tx->tx_sync_more_cv);
cv_destroy(&tx->tx_sync_done_cv);
cv_destroy(&tx->tx_quiesce_more_cv);
cv_destroy(&tx->tx_quiesce_done_cv);
cv_destroy(&tx->tx_exit_cv);
for (c = 0; c < max_ncpus; c++) {
int i;
mutex_destroy(&tx->tx_cpu[c].tc_open_lock);
mutex_destroy(&tx->tx_cpu[c].tc_lock);
for (i = 0; i < TXG_SIZE; i++) {
cv_destroy(&tx->tx_cpu[c].tc_cv[i]);
list_destroy(&tx->tx_cpu[c].tc_callbacks[i]);
}
}
if (tx->tx_commit_cb_taskq != NULL)
taskq_destroy(tx->tx_commit_cb_taskq);
kmem_free(tx->tx_cpu, max_ncpus * sizeof (tx_cpu_t));
bzero(tx, sizeof (tx_state_t));
}
/*
* Start syncing transaction groups.
*/
void
txg_sync_start(dsl_pool_t *dp)
{
tx_state_t *tx = &dp->dp_tx;
mutex_enter(&tx->tx_sync_lock);
dprintf("pool %p\n", dp);
ASSERT0(tx->tx_threads);
tx->tx_threads = 2;
tx->tx_quiesce_thread = thread_create(NULL, 0, txg_quiesce_thread,
dp, 0, &p0, TS_RUN, minclsyspri);
/*
* The sync thread can need a larger-than-default stack size on
* 32-bit x86. This is due in part to nested pools and
* scrub_visitbp() recursion.
*/
tx->tx_sync_thread = thread_create(NULL, 32<<10, txg_sync_thread,
dp, 0, &p0, TS_RUN, minclsyspri);
mutex_exit(&tx->tx_sync_lock);
}
static void
txg_thread_enter(tx_state_t *tx, callb_cpr_t *cpr)
{
CALLB_CPR_INIT(cpr, &tx->tx_sync_lock, callb_generic_cpr, FTAG);
mutex_enter(&tx->tx_sync_lock);
}
static void
txg_thread_exit(tx_state_t *tx, callb_cpr_t *cpr, kthread_t **tpp)
{
ASSERT(*tpp != NULL);
*tpp = NULL;
tx->tx_threads--;
cv_broadcast(&tx->tx_exit_cv);
CALLB_CPR_EXIT(cpr); /* drops &tx->tx_sync_lock */
thread_exit();
}
static void
txg_thread_wait(tx_state_t *tx, callb_cpr_t *cpr, kcondvar_t *cv, clock_t time)
{
CALLB_CPR_SAFE_BEGIN(cpr);
if (time)
(void) cv_timedwait(cv, &tx->tx_sync_lock, time);
else
cv_wait(cv, &tx->tx_sync_lock);
CALLB_CPR_SAFE_END(cpr, &tx->tx_sync_lock);
}
/*
* Stop syncing transaction groups.
*/
void
txg_sync_stop(dsl_pool_t *dp)
{
tx_state_t *tx = &dp->dp_tx;
dprintf("pool %p\n", dp);
/*
* Finish off any work in progress.
*/
ASSERT3U(tx->tx_threads, ==, 2);
/*
* We need to ensure that we've vacated the deferred space_maps.
*/
txg_wait_synced(dp, tx->tx_open_txg + TXG_DEFER_SIZE);
/*
* Wake all sync threads and wait for them to die.
*/
mutex_enter(&tx->tx_sync_lock);
ASSERT3U(tx->tx_threads, ==, 2);
tx->tx_exiting = 1;
cv_broadcast(&tx->tx_quiesce_more_cv);
cv_broadcast(&tx->tx_quiesce_done_cv);
cv_broadcast(&tx->tx_sync_more_cv);
while (tx->tx_threads != 0)
cv_wait(&tx->tx_exit_cv, &tx->tx_sync_lock);
tx->tx_exiting = 0;
mutex_exit(&tx->tx_sync_lock);
}
uint64_t
txg_hold_open(dsl_pool_t *dp, txg_handle_t *th)
{
tx_state_t *tx = &dp->dp_tx;
tx_cpu_t *tc = &tx->tx_cpu[CPU_SEQID];
uint64_t txg;
mutex_enter(&tc->tc_open_lock);
txg = tx->tx_open_txg;
mutex_enter(&tc->tc_lock);
tc->tc_count[txg & TXG_MASK]++;
mutex_exit(&tc->tc_lock);
th->th_cpu = tc;
th->th_txg = txg;
return (txg);
}
void
txg_rele_to_quiesce(txg_handle_t *th)
{
tx_cpu_t *tc = th->th_cpu;
ASSERT(!MUTEX_HELD(&tc->tc_lock));
mutex_exit(&tc->tc_open_lock);
}
void
txg_register_callbacks(txg_handle_t *th, list_t *tx_callbacks)
{
tx_cpu_t *tc = th->th_cpu;
int g = th->th_txg & TXG_MASK;
mutex_enter(&tc->tc_lock);
list_move_tail(&tc->tc_callbacks[g], tx_callbacks);
mutex_exit(&tc->tc_lock);
}
void
txg_rele_to_sync(txg_handle_t *th)
{
tx_cpu_t *tc = th->th_cpu;
int g = th->th_txg & TXG_MASK;
mutex_enter(&tc->tc_lock);
ASSERT(tc->tc_count[g] != 0);
if (--tc->tc_count[g] == 0)
cv_broadcast(&tc->tc_cv[g]);
mutex_exit(&tc->tc_lock);
th->th_cpu = NULL; /* defensive */
}
/*
* Blocks until all transactions in the group are committed.
*
* On return, the transaction group has reached a stable state in which it can
* then be passed off to the syncing context.
*/
static __noinline void
txg_quiesce(dsl_pool_t *dp, uint64_t txg)
{
tx_state_t *tx = &dp->dp_tx;
int g = txg & TXG_MASK;
int c;
/*
* Grab all tc_open_locks so nobody else can get into this txg.
*/
for (c = 0; c < max_ncpus; c++)
mutex_enter(&tx->tx_cpu[c].tc_open_lock);
ASSERT(txg == tx->tx_open_txg);
tx->tx_open_txg++;
tx->tx_open_time = gethrtime();
DTRACE_PROBE2(txg__quiescing, dsl_pool_t *, dp, uint64_t, txg);
DTRACE_PROBE2(txg__opened, dsl_pool_t *, dp, uint64_t, tx->tx_open_txg);
/*
* Now that we've incremented tx_open_txg, we can let threads
* enter the next transaction group.
*/
for (c = 0; c < max_ncpus; c++)
mutex_exit(&tx->tx_cpu[c].tc_open_lock);
/*
* Quiesce the transaction group by waiting for everyone to txg_exit().
*/
for (c = 0; c < max_ncpus; c++) {
tx_cpu_t *tc = &tx->tx_cpu[c];
mutex_enter(&tc->tc_lock);
while (tc->tc_count[g] != 0)
cv_wait(&tc->tc_cv[g], &tc->tc_lock);
mutex_exit(&tc->tc_lock);
}
}
static void
txg_do_callbacks(void *arg)
{
list_t *cb_list = arg;
dmu_tx_do_callbacks(cb_list, 0);
list_destroy(cb_list);
kmem_free(cb_list, sizeof (list_t));
}
/*
* Dispatch the commit callbacks registered on this txg to worker threads.
*
* If no callbacks are registered for a given TXG, nothing happens.
* This function creates a taskq for the associated pool, if needed.
*/
static void
txg_dispatch_callbacks(dsl_pool_t *dp, uint64_t txg)
{
int c;
tx_state_t *tx = &dp->dp_tx;
list_t *cb_list;
for (c = 0; c < max_ncpus; c++) {
tx_cpu_t *tc = &tx->tx_cpu[c];
/*
* No need to lock tx_cpu_t at this point, since this can
* only be called once a txg has been synced.
*/
int g = txg & TXG_MASK;
if (list_is_empty(&tc->tc_callbacks[g]))
continue;
if (tx->tx_commit_cb_taskq == NULL) {
/*
* Commit callback taskq hasn't been created yet.
*/
tx->tx_commit_cb_taskq = taskq_create("tx_commit_cb",
max_ncpus, minclsyspri, max_ncpus, max_ncpus * 2,
TASKQ_PREPOPULATE);
}
cb_list = kmem_alloc(sizeof (list_t), KM_SLEEP);
list_create(cb_list, sizeof (dmu_tx_callback_t),
offsetof(dmu_tx_callback_t, dcb_node));
list_move_tail(cb_list, &tc->tc_callbacks[g]);
(void) taskq_dispatch(tx->tx_commit_cb_taskq, (task_func_t *)
txg_do_callbacks, cb_list, TQ_SLEEP);
}
}
static boolean_t
txg_is_syncing(dsl_pool_t *dp)
{
tx_state_t *tx = &dp->dp_tx;
ASSERT(MUTEX_HELD(&tx->tx_sync_lock));
return (tx->tx_syncing_txg != 0);
}
static boolean_t
txg_is_quiescing(dsl_pool_t *dp)
{
tx_state_t *tx = &dp->dp_tx;
ASSERT(MUTEX_HELD(&tx->tx_sync_lock));
return (tx->tx_quiescing_txg != 0);
}
static boolean_t
txg_has_quiesced_to_sync(dsl_pool_t *dp)
{
tx_state_t *tx = &dp->dp_tx;
ASSERT(MUTEX_HELD(&tx->tx_sync_lock));
return (tx->tx_quiesced_txg != 0);
}
static void
txg_sync_thread(void *arg)
{
dsl_pool_t *dp = arg;
spa_t *spa = dp->dp_spa;
tx_state_t *tx = &dp->dp_tx;
callb_cpr_t cpr;
uint64_t start, delta;
txg_thread_enter(tx, &cpr);
start = delta = 0;
for (;;) {
uint64_t timeout = zfs_txg_timeout * hz;
uint64_t timer;
uint64_t txg;
uint64_t dirty_min_bytes =
zfs_dirty_data_max * zfs_dirty_data_sync_pct / 100;
/*
* We sync when we're scanning, there's someone waiting
* on us, or the quiesce thread has handed off a txg to
* us, or we have reached our timeout.
*/
timer = (delta >= timeout ? 0 : timeout - delta);
while (!dsl_scan_active(dp->dp_scan) &&
!tx->tx_exiting && timer > 0 &&
tx->tx_synced_txg >= tx->tx_sync_txg_waiting &&
!txg_has_quiesced_to_sync(dp) &&
dp->dp_dirty_total < dirty_min_bytes) {
dprintf("waiting; tx_synced=%llu waiting=%llu dp=%p\n",
tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
txg_thread_wait(tx, &cpr, &tx->tx_sync_more_cv, timer);
delta = ddi_get_lbolt() - start;
timer = (delta > timeout ? 0 : timeout - delta);
}
/*
* Wait until the quiesce thread hands off a txg to us,
* prompting it to do so if necessary.
*/
while (!tx->tx_exiting && !txg_has_quiesced_to_sync(dp)) {
if (tx->tx_quiesce_txg_waiting < tx->tx_open_txg+1)
tx->tx_quiesce_txg_waiting = tx->tx_open_txg+1;
cv_broadcast(&tx->tx_quiesce_more_cv);
txg_thread_wait(tx, &cpr, &tx->tx_quiesce_done_cv, 0);
}
if (tx->tx_exiting)
txg_thread_exit(tx, &cpr, &tx->tx_sync_thread);
/*
* Consume the quiesced txg which has been handed off to
* us. This may cause the quiescing thread to now be
* able to quiesce another txg, so we must signal it.
*/
ASSERT(tx->tx_quiesced_txg != 0);
txg = tx->tx_quiesced_txg;
tx->tx_quiesced_txg = 0;
tx->tx_syncing_txg = txg;
DTRACE_PROBE2(txg__syncing, dsl_pool_t *, dp, uint64_t, txg);
cv_broadcast(&tx->tx_quiesce_more_cv);
dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
mutex_exit(&tx->tx_sync_lock);
start = ddi_get_lbolt();
spa_sync(spa, txg);
delta = ddi_get_lbolt() - start;
mutex_enter(&tx->tx_sync_lock);
tx->tx_synced_txg = txg;
tx->tx_syncing_txg = 0;
DTRACE_PROBE2(txg__synced, dsl_pool_t *, dp, uint64_t, txg);
cv_broadcast(&tx->tx_sync_done_cv);
/*
* Dispatch commit callbacks to worker threads.
*/
txg_dispatch_callbacks(dp, txg);
}
}
static void
txg_quiesce_thread(void *arg)
{
dsl_pool_t *dp = arg;
tx_state_t *tx = &dp->dp_tx;
callb_cpr_t cpr;
txg_thread_enter(tx, &cpr);
for (;;) {
uint64_t txg;
/*
* We quiesce when there's someone waiting on us.
* However, we can only have one txg in "quiescing" or
* "quiesced, waiting to sync" state. So we wait until
* the "quiesced, waiting to sync" txg has been consumed
* by the sync thread.
*/
while (!tx->tx_exiting &&
(tx->tx_open_txg >= tx->tx_quiesce_txg_waiting ||
txg_has_quiesced_to_sync(dp)))
txg_thread_wait(tx, &cpr, &tx->tx_quiesce_more_cv, 0);
if (tx->tx_exiting)
txg_thread_exit(tx, &cpr, &tx->tx_quiesce_thread);
txg = tx->tx_open_txg;
dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
txg, tx->tx_quiesce_txg_waiting,
tx->tx_sync_txg_waiting);
tx->tx_quiescing_txg = txg;
mutex_exit(&tx->tx_sync_lock);
txg_quiesce(dp, txg);
mutex_enter(&tx->tx_sync_lock);
/*
* Hand this txg off to the sync thread.
*/
dprintf("quiesce done, handing off txg %llu\n", txg);
tx->tx_quiescing_txg = 0;
tx->tx_quiesced_txg = txg;
DTRACE_PROBE2(txg__quiesced, dsl_pool_t *, dp, uint64_t, txg);
cv_broadcast(&tx->tx_sync_more_cv);
cv_broadcast(&tx->tx_quiesce_done_cv);
}
}
/*
* Delay this thread by delay nanoseconds if we are still in the open
* transaction group and there is already a waiting txg quiesing or quiesced.
* Abort the delay if this txg stalls or enters the quiesing state.
*/
void
txg_delay(dsl_pool_t *dp, uint64_t txg, hrtime_t delay, hrtime_t resolution)
{
tx_state_t *tx = &dp->dp_tx;
hrtime_t start = gethrtime();
/* don't delay if this txg could transition to quiescing immediately */
if (tx->tx_open_txg > txg ||
tx->tx_syncing_txg == txg-1 || tx->tx_synced_txg == txg-1)
return;
mutex_enter(&tx->tx_sync_lock);
if (tx->tx_open_txg > txg || tx->tx_synced_txg == txg-1) {
mutex_exit(&tx->tx_sync_lock);
return;
}
while (gethrtime() - start < delay &&
tx->tx_syncing_txg < txg-1 && !txg_stalled(dp)) {
(void) cv_timedwait_hires(&tx->tx_quiesce_more_cv,
&tx->tx_sync_lock, delay, resolution, 0);
}
mutex_exit(&tx->tx_sync_lock);
}
void
txg_wait_synced(dsl_pool_t *dp, uint64_t txg)
{
tx_state_t *tx = &dp->dp_tx;
ASSERT(!dsl_pool_config_held(dp));
mutex_enter(&tx->tx_sync_lock);
ASSERT3U(tx->tx_threads, ==, 2);
if (txg == 0)
txg = tx->tx_open_txg + TXG_DEFER_SIZE;
if (tx->tx_sync_txg_waiting < txg)
tx->tx_sync_txg_waiting = txg;
dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
while (tx->tx_synced_txg < txg) {
dprintf("broadcasting sync more "
"tx_synced=%llu waiting=%llu dp=%p\n",
tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
cv_broadcast(&tx->tx_sync_more_cv);
cv_wait(&tx->tx_sync_done_cv, &tx->tx_sync_lock);
}
mutex_exit(&tx->tx_sync_lock);
}
void
txg_wait_open(dsl_pool_t *dp, uint64_t txg)
{
tx_state_t *tx = &dp->dp_tx;
ASSERT(!dsl_pool_config_held(dp));
mutex_enter(&tx->tx_sync_lock);
ASSERT3U(tx->tx_threads, ==, 2);
if (txg == 0)
txg = tx->tx_open_txg + 1;
if (tx->tx_quiesce_txg_waiting < txg)
tx->tx_quiesce_txg_waiting = txg;
dprintf("txg=%llu quiesce_txg=%llu sync_txg=%llu\n",
txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
while (tx->tx_open_txg < txg) {
cv_broadcast(&tx->tx_quiesce_more_cv);
cv_wait(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock);
}
mutex_exit(&tx->tx_sync_lock);
}
/*
* If there isn't a txg syncing or in the pipeline, push another txg through
* the pipeline by queiscing the open txg.
*/
void
txg_kick(dsl_pool_t *dp)
{
tx_state_t *tx = &dp->dp_tx;
ASSERT(!dsl_pool_config_held(dp));
mutex_enter(&tx->tx_sync_lock);
if (!txg_is_syncing(dp) &&
!txg_is_quiescing(dp) &&
tx->tx_quiesce_txg_waiting <= tx->tx_open_txg &&
tx->tx_sync_txg_waiting <= tx->tx_synced_txg &&
tx->tx_quiesced_txg <= tx->tx_synced_txg) {
tx->tx_quiesce_txg_waiting = tx->tx_open_txg + 1;
cv_broadcast(&tx->tx_quiesce_more_cv);
}
mutex_exit(&tx->tx_sync_lock);
}
boolean_t
txg_stalled(dsl_pool_t *dp)
{
tx_state_t *tx = &dp->dp_tx;
return (tx->tx_quiesce_txg_waiting > tx->tx_open_txg);
}
boolean_t
txg_sync_waiting(dsl_pool_t *dp)
{
tx_state_t *tx = &dp->dp_tx;
return (tx->tx_syncing_txg <= tx->tx_sync_txg_waiting ||
tx->tx_quiesced_txg != 0);
}
/*
* Verify that this txg is active (open, quiescing, syncing). Non-active
* txg's should not be manipulated.
*/
void
txg_verify(spa_t *spa, uint64_t txg)
{
dsl_pool_t *dp = spa_get_dsl(spa);
if (txg <= TXG_INITIAL || txg == ZILTEST_TXG)
return;
ASSERT3U(txg, <=, dp->dp_tx.tx_open_txg);
ASSERT3U(txg, >=, dp->dp_tx.tx_synced_txg);
ASSERT3U(txg, >=, dp->dp_tx.tx_open_txg - TXG_CONCURRENT_STATES);
}
/*
* Per-txg object lists.
*/
void
txg_list_create(txg_list_t *tl, spa_t *spa, size_t offset)
{
int t;
mutex_init(&tl->tl_lock, NULL, MUTEX_DEFAULT, NULL);
tl->tl_offset = offset;
tl->tl_spa = spa;
for (t = 0; t < TXG_SIZE; t++)
tl->tl_head[t] = NULL;
}
void
txg_list_destroy(txg_list_t *tl)
{
int t;
for (t = 0; t < TXG_SIZE; t++)
ASSERT(txg_list_empty(tl, t));
mutex_destroy(&tl->tl_lock);
}
boolean_t
txg_list_empty(txg_list_t *tl, uint64_t txg)
{
txg_verify(tl->tl_spa, txg);
return (tl->tl_head[txg & TXG_MASK] == NULL);
}
/*
* Returns true if all txg lists are empty.
*
* Warning: this is inherently racy (an item could be added immediately
* after this function returns). We don't bother with the lock because
* it wouldn't change the semantics.
*/
boolean_t
txg_all_lists_empty(txg_list_t *tl)
{
for (int i = 0; i < TXG_SIZE; i++) {
if (!txg_list_empty(tl, i)) {
return (B_FALSE);
}
}
return (B_TRUE);
}
/*
* Add an entry to the list (unless it's already on the list).
* Returns B_TRUE if it was actually added.
*/
boolean_t
txg_list_add(txg_list_t *tl, void *p, uint64_t txg)
{
int t = txg & TXG_MASK;
txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
boolean_t add;
txg_verify(tl->tl_spa, txg);
mutex_enter(&tl->tl_lock);
add = (tn->tn_member[t] == 0);
if (add) {
tn->tn_member[t] = 1;
tn->tn_next[t] = tl->tl_head[t];
tl->tl_head[t] = tn;
}
mutex_exit(&tl->tl_lock);
return (add);
}
/*
* Add an entry to the end of the list, unless it's already on the list.
* (walks list to find end)
* Returns B_TRUE if it was actually added.
*/
boolean_t
txg_list_add_tail(txg_list_t *tl, void *p, uint64_t txg)
{
int t = txg & TXG_MASK;
txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
boolean_t add;
txg_verify(tl->tl_spa, txg);
mutex_enter(&tl->tl_lock);
add = (tn->tn_member[t] == 0);
if (add) {
txg_node_t **tp;
for (tp = &tl->tl_head[t]; *tp != NULL; tp = &(*tp)->tn_next[t])
continue;
tn->tn_member[t] = 1;
tn->tn_next[t] = NULL;
*tp = tn;
}
mutex_exit(&tl->tl_lock);
return (add);
}
/*
* Remove the head of the list and return it.
*/
void *
txg_list_remove(txg_list_t *tl, uint64_t txg)
{
int t = txg & TXG_MASK;
txg_node_t *tn;
void *p = NULL;
txg_verify(tl->tl_spa, txg);
mutex_enter(&tl->tl_lock);
if ((tn = tl->tl_head[t]) != NULL) {
ASSERT(tn->tn_member[t]);
ASSERT(tn->tn_next[t] == NULL || tn->tn_next[t]->tn_member[t]);
p = (char *)tn - tl->tl_offset;
tl->tl_head[t] = tn->tn_next[t];
tn->tn_next[t] = NULL;
tn->tn_member[t] = 0;
}
mutex_exit(&tl->tl_lock);
return (p);
}
/*
* Remove a specific item from the list and return it.
*/
void *
txg_list_remove_this(txg_list_t *tl, void *p, uint64_t txg)
{
int t = txg & TXG_MASK;
txg_node_t *tn, **tp;
txg_verify(tl->tl_spa, txg);
mutex_enter(&tl->tl_lock);
for (tp = &tl->tl_head[t]; (tn = *tp) != NULL; tp = &tn->tn_next[t]) {
if ((char *)tn - tl->tl_offset == p) {
*tp = tn->tn_next[t];
tn->tn_next[t] = NULL;
tn->tn_member[t] = 0;
mutex_exit(&tl->tl_lock);
return (p);
}
}
mutex_exit(&tl->tl_lock);
return (NULL);
}
boolean_t
txg_list_member(txg_list_t *tl, void *p, uint64_t txg)
{
int t = txg & TXG_MASK;
txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
txg_verify(tl->tl_spa, txg);
return (tn->tn_member[t] != 0);
}
/*
* Walk a txg list -- only safe if you know it's not changing.
*/
void *
txg_list_head(txg_list_t *tl, uint64_t txg)
{
int t = txg & TXG_MASK;
txg_node_t *tn = tl->tl_head[t];
txg_verify(tl->tl_spa, txg);
return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
}
void *
txg_list_next(txg_list_t *tl, void *p, uint64_t txg)
{
int t = txg & TXG_MASK;
txg_node_t *tn = (txg_node_t *)((char *)p + tl->tl_offset);
txg_verify(tl->tl_spa, txg);
tn = tn->tn_next[t];
return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
}
