| /* |
| * 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, 2017 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/zil.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(void *arg); |
| static void txg_quiesce_thread(void *arg); |
| |
| 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_NOLOCKDEP, |
| 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); |
| |
| 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); |
| |
| ASSERT0(tx->tx_threads); |
| |
| tx->tx_threads = 2; |
| |
| tx->tx_quiesce_thread = thread_create(NULL, 0, txg_quiesce_thread, |
| dp, 0, &p0, TS_RUN, defclsyspri); |
| |
| /* |
| * 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, 0, txg_sync_thread, |
| dp, 0, &p0, TS_RUN, defclsyspri); |
| |
| 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); |
| |
| /* |
| * cv_wait_sig() is used instead of cv_wait() in order to prevent |
| * this process from incorrectly contributing to the system load |
| * average when idle. |
| */ |
| if (time) { |
| (void) cv_timedwait_sig(cv, &tx->tx_sync_lock, |
| ddi_get_lbolt() + time); |
| } else { |
| cv_wait_sig(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; |
| 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; |
| uint64_t tx_open_time; |
| 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 = 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); |
| |
| spa_txg_history_set(dp->dp_spa, txg, TXG_STATE_OPEN, tx_open_time); |
| spa_txg_history_add(dp->dp_spa, txg + 1, tx_open_time); |
| |
| /* |
| * 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", |
| boot_ncpus, defclsyspri, boot_ncpus, boot_ncpus * 2, |
| TASKQ_PREPOPULATE | TASKQ_DYNAMIC); |
| } |
| |
| 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); |
| } |
| } |
| |
| /* |
| * 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_outstanding(tx->tx_commit_cb_taskq, 0); |
| } |
| |
| 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; |
| clock_t start, delta; |
| |
| (void) spl_fstrans_mark(); |
| txg_thread_enter(tx, &cpr); |
| |
| start = delta = 0; |
| for (;;) { |
| clock_t timeout = zfs_txg_timeout * hz; |
| clock_t timer; |
| uint64_t txg; |
| uint64_t dirty_min_bytes = |
| zfs_dirty_data_max * zfs_dirty_data_sync_percent / 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); |
| |
| txg_stat_t *ts = spa_txg_history_init_io(spa, txg, dp); |
| start = ddi_get_lbolt(); |
| spa_sync(spa, txg); |
| delta = ddi_get_lbolt() - start; |
| spa_txg_history_fini_io(spa, ts); |
| |
| 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 quiescing or quiesced. |
| * Abort the delay if this txg stalls or enters the quiescing 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); |
| } |
| |
| static boolean_t |
| txg_wait_synced_impl(dsl_pool_t *dp, uint64_t txg, boolean_t wait_sig) |
| { |
| 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); |
| if (wait_sig) { |
| /* |
| * Condition wait here but stop if the thread receives a |
| * signal. The caller may call txg_wait_synced*() again |
| * to resume waiting for this txg. |
| */ |
| if (cv_wait_io_sig(&tx->tx_sync_done_cv, |
| &tx->tx_sync_lock) == 0) { |
| mutex_exit(&tx->tx_sync_lock); |
| return (B_TRUE); |
| } |
| } else { |
| cv_wait_io(&tx->tx_sync_done_cv, &tx->tx_sync_lock); |
| } |
| } |
| mutex_exit(&tx->tx_sync_lock); |
| return (B_FALSE); |
| } |
| |
| void |
| txg_wait_synced(dsl_pool_t *dp, uint64_t txg) |
| { |
| VERIFY0(txg_wait_synced_impl(dp, txg, B_FALSE)); |
| } |
| |
| /* |
| * Similar to a txg_wait_synced but it can be interrupted from a signal. |
| * Returns B_TRUE if the thread was signaled while waiting. |
| */ |
| boolean_t |
| txg_wait_synced_sig(dsl_pool_t *dp, uint64_t txg) |
| { |
| return (txg_wait_synced_impl(dp, txg, B_TRUE)); |
| } |
| |
| /* |
| * Wait for the specified open transaction group. Set should_quiesce |
| * when the current open txg should be quiesced immediately. |
| */ |
| void |
| txg_wait_open(dsl_pool_t *dp, uint64_t txg, boolean_t should_quiesce) |
| { |
| 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 && should_quiesce) |
| 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); |
| /* |
| * Callers setting should_quiesce will use cv_wait_io() and |
| * be accounted for as iowait time. Otherwise, the caller is |
| * understood to be idle and cv_wait_sig() is used to prevent |
| * incorrectly inflating the system load average. |
| */ |
| if (should_quiesce == B_TRUE) { |
| cv_wait_io(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock); |
| } else { |
| cv_wait_sig(&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 quiescing 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. |
| */ |
| #ifdef ZFS_DEBUG |
| void |
| txg_verify(spa_t *spa, uint64_t txg) |
| { |
| ASSERTV(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); |
| } |
| #endif |
| |
| /* |
| * 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; |
| } |
| |
| static boolean_t |
| txg_list_empty_impl(txg_list_t *tl, uint64_t txg) |
| { |
| ASSERT(MUTEX_HELD(&tl->tl_lock)); |
| TXG_VERIFY(tl->tl_spa, txg); |
| return (tl->tl_head[txg & TXG_MASK] == NULL); |
| } |
| |
| boolean_t |
| txg_list_empty(txg_list_t *tl, uint64_t txg) |
| { |
| mutex_enter(&tl->tl_lock); |
| boolean_t ret = txg_list_empty_impl(tl, txg); |
| mutex_exit(&tl->tl_lock); |
| |
| return (ret); |
| } |
| |
| void |
| txg_list_destroy(txg_list_t *tl) |
| { |
| int t; |
| |
| mutex_enter(&tl->tl_lock); |
| for (t = 0; t < TXG_SIZE; t++) |
| ASSERT(txg_list_empty_impl(tl, t)); |
| mutex_exit(&tl->tl_lock); |
| |
| mutex_destroy(&tl->tl_lock); |
| } |
| |
| /* |
| * Returns true if all txg lists are empty. |
| * |
| * Warning: this is inherently racy (an item could be added immediately |
| * after this function returns). |
| */ |
| boolean_t |
| txg_all_lists_empty(txg_list_t *tl) |
| { |
| mutex_enter(&tl->tl_lock); |
| for (int i = 0; i < TXG_SIZE; i++) { |
| if (!txg_list_empty_impl(tl, i)) { |
| mutex_exit(&tl->tl_lock); |
| return (B_FALSE); |
| } |
| } |
| mutex_exit(&tl->tl_lock); |
| 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 |
| */ |
| void * |
| txg_list_head(txg_list_t *tl, uint64_t txg) |
| { |
| int t = txg & TXG_MASK; |
| txg_node_t *tn; |
| |
| mutex_enter(&tl->tl_lock); |
| tn = tl->tl_head[t]; |
| mutex_exit(&tl->tl_lock); |
| |
| 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); |
| |
| mutex_enter(&tl->tl_lock); |
| tn = tn->tn_next[t]; |
| mutex_exit(&tl->tl_lock); |
| |
| return (tn == NULL ? NULL : (char *)tn - tl->tl_offset); |
| } |
| |
| #if defined(_KERNEL) |
| 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 |