# HG changeset patch # User George Wilson # Date 1366738302 28800 # Node ID 624fa8f61951b5f4160f55b9cdaf5f37f82f59c4 # Parent 9915df7eb3045d55fcbd9b9b62f54e45d2643ab4 3642 dsl_scan_active() should not issue I/O to determine if async destroying is active 3643 txg_delay should not hold the tc_lock Reviewed by: Matthew Ahrens Reviewed by: Adam Leventhal Approved by: Gordon Ross diff -r 9915df7eb304 -r 624fa8f61951 usr/src/uts/common/fs/zfs/dsl_destroy.c --- a/usr/src/uts/common/fs/zfs/dsl_destroy.c Wed Apr 17 20:25:52 2013 -0400 +++ b/usr/src/uts/common/fs/zfs/dsl_destroy.c Tue Apr 23 09:31:42 2013 -0800 @@ -753,12 +753,16 @@ zil_destroy_sync(dmu_objset_zil(os), tx); if (!spa_feature_is_active(dp->dp_spa, async_destroy)) { + dsl_scan_t *scn = dp->dp_scan; + spa_feature_incr(dp->dp_spa, async_destroy, tx); dp->dp_bptree_obj = bptree_alloc(mos, tx); VERIFY0(zap_add(mos, DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_BPTREE_OBJ, sizeof (uint64_t), 1, &dp->dp_bptree_obj, tx)); + ASSERT(!scn->scn_async_destroying); + scn->scn_async_destroying = B_TRUE; } used = ds->ds_dir->dd_phys->dd_used_bytes; diff -r 9915df7eb304 -r 624fa8f61951 usr/src/uts/common/fs/zfs/dsl_scan.c --- a/usr/src/uts/common/fs/zfs/dsl_scan.c Wed Apr 17 20:25:52 2013 -0400 +++ b/usr/src/uts/common/fs/zfs/dsl_scan.c Tue Apr 23 09:31:42 2013 -0800 @@ -95,6 +95,15 @@ scn = dp->dp_scan = kmem_zalloc(sizeof (dsl_scan_t), KM_SLEEP); scn->scn_dp = dp; + /* + * It's possible that we're resuming a scan after a reboot so + * make sure that the scan_async_destroying flag is initialized + * appropriately. + */ + ASSERT(!scn->scn_async_destroying); + scn->scn_async_destroying = spa_feature_is_active(dp->dp_spa, + &spa_feature_table[SPA_FEATURE_ASYNC_DESTROY]); + err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT, "scrub_func", sizeof (uint64_t), 1, &f); if (err == 0) { @@ -1344,13 +1353,10 @@ if (spa_shutting_down(spa)) return (B_FALSE); - if (scn->scn_phys.scn_state == DSS_SCANNING) + if (scn->scn_phys.scn_state == DSS_SCANNING || + scn->scn_async_destroying) return (B_TRUE); - if (spa_feature_is_active(spa, - &spa_feature_table[SPA_FEATURE_ASYNC_DESTROY])) { - return (B_TRUE); - } if (spa_version(scn->scn_dp->dp_spa) >= SPA_VERSION_DEADLISTS) { (void) bpobj_space(&scn->scn_dp->dp_free_bpobj, &used, &comp, &uncomp); @@ -1406,6 +1412,7 @@ if (err == 0 && spa_feature_is_active(spa, &spa_feature_table[SPA_FEATURE_ASYNC_DESTROY])) { + ASSERT(scn->scn_async_destroying); scn->scn_is_bptree = B_TRUE; scn->scn_zio_root = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED); @@ -1426,6 +1433,7 @@ VERIFY0(bptree_free(dp->dp_meta_objset, dp->dp_bptree_obj, tx)); dp->dp_bptree_obj = 0; + scn->scn_async_destroying = B_FALSE; } } if (scn->scn_visited_this_txg) { diff -r 9915df7eb304 -r 624fa8f61951 usr/src/uts/common/fs/zfs/sys/dsl_scan.h --- a/usr/src/uts/common/fs/zfs/sys/dsl_scan.h Wed Apr 17 20:25:52 2013 -0400 +++ b/usr/src/uts/common/fs/zfs/sys/dsl_scan.h Tue Apr 23 09:31:42 2013 -0800 @@ -20,7 +20,7 @@ */ /* * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved. - * Copyright (c) 2012 by Delphix. All rights reserved. + * Copyright (c) 2013 by Delphix. All rights reserved. */ #ifndef _SYS_DSL_SCAN_H @@ -82,6 +82,7 @@ /* for freeing blocks */ boolean_t scn_is_bptree; + boolean_t scn_async_destroying; /* for debugging / information */ uint64_t scn_visited_this_txg; diff -r 9915df7eb304 -r 624fa8f61951 usr/src/uts/common/fs/zfs/sys/txg_impl.h --- a/usr/src/uts/common/fs/zfs/sys/txg_impl.h Wed Apr 17 20:25:52 2013 -0400 +++ b/usr/src/uts/common/fs/zfs/sys/txg_impl.h Tue Apr 23 09:31:42 2013 -0800 @@ -24,7 +24,7 @@ */ /* - * Copyright (c) 2012 by Delphix. All rights reserved. + * Copyright (c) 2013 by Delphix. All rights reserved. */ #ifndef _SYS_TXG_IMPL_H @@ -37,14 +37,55 @@ extern "C" { #endif +/* + * The tx_cpu structure is a per-cpu structure that is used to track + * the number of active transaction holds (tc_count). As transactions + * are assigned into a transaction group the appropriate tc_count is + * incremented to indicate that there are pending changes that have yet + * to quiesce. Consumers evenutally call txg_rele_to_sync() to decrement + * the tc_count. A transaction group is not considered quiesced until all + * tx_cpu structures have reached a tc_count of zero. + * + * This structure is a per-cpu structure by design. Updates to this structure + * are frequent and concurrent. Having a single structure would result in + * heavy lock contention so a per-cpu design was implemented. With the fanned + * out mutex design, consumers only need to lock the mutex associated with + * thread's cpu. + * + * The tx_cpu contains two locks, the tc_lock and tc_open_lock. + * The tc_lock is used to protect all members of the tx_cpu structure with + * the exception of the tc_open_lock. This lock should only be held for a + * short period of time, typically when updating the value of tc_count. + * + * The tc_open_lock protects the tx_open_txg member of the tx_state structure. + * This lock is used to ensure that transactions are only assigned into + * the current open transaction group. In order to move the current open + * transaction group to the quiesce phase, the txg_quiesce thread must + * grab all tc_open_locks, increment the tx_open_txg, and drop the locks. + * The tc_open_lock is held until the transaction is assigned into the + * transaction group. Typically, this is a short operation but if throttling + * is occuring it may be held for longer periods of time. + */ struct tx_cpu { - kmutex_t tc_lock; + kmutex_t tc_open_lock; /* protects tx_open_txg */ + kmutex_t tc_lock; /* protects the rest of this struct */ kcondvar_t tc_cv[TXG_SIZE]; uint64_t tc_count[TXG_SIZE]; /* tx hold count on each txg */ list_t tc_callbacks[TXG_SIZE]; /* commit cb list */ - char tc_pad[16]; /* pad to fill 3 cache lines */ + char tc_pad[8]; /* pad to fill 3 cache lines */ }; +/* + * The tx_state structure maintains the state information about the different + * stages of the pool's transcation groups. A per pool tx_state structure + * is used to track this information. The tx_state structure also points to + * an array of tx_cpu structures (described above). Although the tx_sync_lock + * is used to protect the members of this structure, it is not used to + * protect the tx_open_txg. Instead a special lock in the tx_cpu structure + * is used. Readers of tx_open_txg must grab the per-cpu tc_open_lock. + * Any thread wishing to update tx_open_txg must grab the tc_open_lock on + * every cpu (see txg_quiesce()). + */ typedef struct tx_state { tx_cpu_t *tx_cpu; /* protects access to tx_open_txg */ kmutex_t tx_sync_lock; /* protects the rest of this struct */ diff -r 9915df7eb304 -r 624fa8f61951 usr/src/uts/common/fs/zfs/txg.c --- a/usr/src/uts/common/fs/zfs/txg.c Wed Apr 17 20:25:52 2013 -0400 +++ b/usr/src/uts/common/fs/zfs/txg.c Tue Apr 23 09:31:42 2013 -0800 @@ -126,6 +126,8 @@ 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); @@ -168,6 +170,7 @@ 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]); @@ -292,10 +295,12 @@ tx_cpu_t *tc = &tx->tx_cpu[CPU_SEQID]; uint64_t txg; - mutex_enter(&tc->tc_lock); + mutex_enter(&tc->tc_open_lock); + txg = tx->tx_open_txg; - 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; @@ -308,7 +313,8 @@ { tx_cpu_t *tc = th->th_cpu; - mutex_exit(&tc->tc_lock); + ASSERT(!MUTEX_HELD(&tc->tc_lock)); + mutex_exit(&tc->tc_open_lock); } void @@ -345,10 +351,10 @@ int c; /* - * Grab all tx_cpu locks so nobody else can get into this txg. + * 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_lock); + mutex_enter(&tx->tx_cpu[c].tc_open_lock); ASSERT(txg == tx->tx_open_txg); tx->tx_open_txg++; @@ -361,7 +367,7 @@ * enter the next transaction group. */ for (c = 0; c < max_ncpus; c++) - mutex_exit(&tx->tx_cpu[c].tc_lock); + mutex_exit(&tx->tx_cpu[c].tc_open_lock); /* * Quiesce the transaction group by waiting for everyone to txg_exit().