freebsd-nq/module/zfs/txg.c
Ned Bass 49ee64e5e6 Remove duplicate typedefs from trace.h
Older versions of GCC (e.g. GCC 4.4.7 on RHEL6) do not allow duplicate
typedef declarations with the same type. The trace.h header contains
some typedefs to avoid 'unknown type' errors for C files that haven't
declared the type in question. But this causes build failures for C
files that have already declared the type. Newer versions of GCC (e.g.
v4.6) allow duplicate typedefs with the same type unless pedantic error
checking is in force. To support the older versions we need to remove
the duplicate typedefs.

Removal of the typedefs means we can't built tracepoints code using
those types unless the required headers have been included. To
facilitate this, all tracepoint event declarations have been moved out
of trace.h into separate headers. Each new header is explicitly included
from the C file that uses the events defined therein. The trace.h header
is still indirectly included form zfs_context.h and provides the
implementation of the dprintf(), dbgmsg(), and SET_ERROR() interfaces.
This makes those interfaces readily available throughout the code base.
The macros that redefine DTRACE_PROBE* to use Linux tracepoints are also
still provided by trace.h, so it is a prerequisite for the other
trace_*.h headers.

These new Linux implementation-specific headers do introduce a small
divergence from upstream ZFS in several core C files, but this should
not present a significant maintenance burden.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2953
2015-01-06 16:53:24 -08:00

961 lines
25 KiB
C

/*
* 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
* Copyright (c) 2012, 2014 by Delphix. All rights reserved.
*/
#include <sys/zfs_context.h>
#include <sys/txg_impl.h>
#include <sys/dmu_impl.h>
#include <sys/spa_impl.h>
#include <sys/dmu_tx.h>
#include <sys/dsl_pool.h>
#include <sys/dsl_scan.h>
#include <sys/callb.h>
#include <sys/trace_txg.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(dsl_pool_t *dp);
static void txg_quiesce_thread(dsl_pool_t *dp);
int zfs_txg_timeout = 5; /* max 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 = vmem_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;
ASSERT(tx->tx_threads == 0);
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);
vmem_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);
ASSERT(tx->tx_threads == 0);
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_interruptible(cv, &tx->tx_sync_lock,
ddi_get_lbolt() + time);
else
cv_wait_interruptible(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.
*/
ASSERT(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);
ASSERT(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;
uint64_t txg;
/*
* It appears the processor id is simply used as a "random"
* number to index into the array, and there isn't any other
* significance to the chosen tx_cpu. Because.. Why not use
* the current cpu to index into the array?
*/
kpreempt_disable();
tc = &tx->tx_cpu[CPU_SEQID];
kpreempt_enable();
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 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();
spa_txg_history_set(dp->dp_spa, txg, TXG_STATE_OPEN, tx->tx_open_time);
spa_txg_history_add(dp->dp_spa, tx->tx_open_txg, tx->tx_open_time);
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);
}
spa_txg_history_set(dp->dp_spa, txg, TXG_STATE_QUIESCED, gethrtime());
}
static void
txg_do_callbacks(list_t *cb_list)
{
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",
100, minclsyspri, max_ncpus, INT_MAX,
TASKQ_THREADS_CPU_PCT | TASKQ_PREPOPULATE);
}
cb_list = kmem_alloc(sizeof (list_t), KM_PUSHPAGE);
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);
}
}
/*
* Wait for pending commit callbacks of already-synced transactions to finish
* processing.
* Calling this function from within a commit callback will deadlock.
*/
void
txg_wait_callbacks(dsl_pool_t *dp)
{
tx_state_t *tx = &dp->dp_tx;
if (tx->tx_commit_cb_taskq != NULL)
taskq_wait(tx->tx_commit_cb_taskq);
}
static void
txg_sync_thread(dsl_pool_t *dp)
{
spa_t *spa = dp->dp_spa;
tx_state_t *tx = &dp->dp_tx;
callb_cpr_t cpr;
vdev_stat_t *vs1, *vs2;
clock_t start, delta;
#ifdef _KERNEL
/*
* Annotate this process with a flag that indicates that it is
* unsafe to use KM_SLEEP during memory allocations due to the
* potential for a deadlock. KM_PUSHPAGE should be used instead.
*/
current->flags |= PF_NOFS;
#endif /* _KERNEL */
txg_thread_enter(tx, &cpr);
vs1 = kmem_alloc(sizeof (vdev_stat_t), KM_PUSHPAGE);
vs2 = kmem_alloc(sizeof (vdev_stat_t), KM_PUSHPAGE);
start = delta = 0;
for (;;) {
clock_t timer, timeout;
uint64_t txg;
uint64_t ndirty;
timeout = zfs_txg_timeout * hz;
/*
* 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 &&
tx->tx_quiesced_txg == 0 &&
dp->dp_dirty_total < zfs_dirty_data_sync) {
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 && tx->tx_quiesced_txg == 0) {
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) {
kmem_free(vs2, sizeof (vdev_stat_t));
kmem_free(vs1, sizeof (vdev_stat_t));
txg_thread_exit(tx, &cpr, &tx->tx_sync_thread);
}
spa_config_enter(spa, SCL_ALL, FTAG, RW_READER);
vdev_get_stats(spa->spa_root_vdev, vs1);
spa_config_exit(spa, SCL_ALL, FTAG);
/*
* 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.
*/
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);
spa_txg_history_set(spa, txg, TXG_STATE_WAIT_FOR_SYNC,
gethrtime());
ndirty = dp->dp_dirty_pertxg[txg & TXG_MASK];
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);
spa_config_enter(spa, SCL_ALL, FTAG, RW_READER);
vdev_get_stats(spa->spa_root_vdev, vs2);
spa_config_exit(spa, SCL_ALL, FTAG);
spa_txg_history_set_io(spa, txg,
vs2->vs_bytes[ZIO_TYPE_READ]-vs1->vs_bytes[ZIO_TYPE_READ],
vs2->vs_bytes[ZIO_TYPE_WRITE]-vs1->vs_bytes[ZIO_TYPE_WRITE],
vs2->vs_ops[ZIO_TYPE_READ]-vs1->vs_ops[ZIO_TYPE_READ],
vs2->vs_ops[ZIO_TYPE_WRITE]-vs1->vs_ops[ZIO_TYPE_WRITE],
ndirty);
spa_txg_history_set(spa, txg, TXG_STATE_SYNCED, gethrtime());
}
}
static void
txg_quiesce_thread(dsl_pool_t *dp)
{
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 ||
tx->tx_quiesced_txg != 0))
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);
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_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);
}
DMU_TX_STAT_BUMP(dmu_tx_delay);
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);
ASSERT(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);
ASSERT(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 (tx->tx_syncing_txg == 0 &&
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);
}
/*
* Per-txg object lists.
*/
void
txg_list_create(txg_list_t *tl, size_t offset)
{
int t;
mutex_init(&tl->tl_lock, NULL, MUTEX_DEFAULT, NULL);
tl->tl_offset = offset;
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)
{
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)
{
int i;
for (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;
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;
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;
mutex_enter(&tl->tl_lock);
if ((tn = tl->tl_head[t]) != NULL) {
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;
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);
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];
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);
tn = tn->tn_next[t];
return (tn == NULL ? NULL : (char *)tn - tl->tl_offset);
}
#if defined(_KERNEL) && defined(HAVE_SPL)
EXPORT_SYMBOL(txg_init);
EXPORT_SYMBOL(txg_fini);
EXPORT_SYMBOL(txg_sync_start);
EXPORT_SYMBOL(txg_sync_stop);
EXPORT_SYMBOL(txg_hold_open);
EXPORT_SYMBOL(txg_rele_to_quiesce);
EXPORT_SYMBOL(txg_rele_to_sync);
EXPORT_SYMBOL(txg_register_callbacks);
EXPORT_SYMBOL(txg_delay);
EXPORT_SYMBOL(txg_wait_synced);
EXPORT_SYMBOL(txg_wait_open);
EXPORT_SYMBOL(txg_wait_callbacks);
EXPORT_SYMBOL(txg_stalled);
EXPORT_SYMBOL(txg_sync_waiting);
module_param(zfs_txg_timeout, int, 0644);
MODULE_PARM_DESC(zfs_txg_timeout, "Max seconds worth of delta per txg");
#endif