/* * 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 https://opensource.org/licenses/CDDL-1.0. * 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. * Copyright 2011 Nexenta Systems, Inc. All rights reserved. * Copyright (c) 2012, 2017 by Delphix. All rights reserved. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include typedef void (*dmu_tx_hold_func_t)(dmu_tx_t *tx, struct dnode *dn, uint64_t arg1, uint64_t arg2); dmu_tx_stats_t dmu_tx_stats = { { "dmu_tx_assigned", KSTAT_DATA_UINT64 }, { "dmu_tx_delay", KSTAT_DATA_UINT64 }, { "dmu_tx_error", KSTAT_DATA_UINT64 }, { "dmu_tx_suspended", KSTAT_DATA_UINT64 }, { "dmu_tx_group", KSTAT_DATA_UINT64 }, { "dmu_tx_memory_reserve", KSTAT_DATA_UINT64 }, { "dmu_tx_memory_reclaim", KSTAT_DATA_UINT64 }, { "dmu_tx_dirty_throttle", KSTAT_DATA_UINT64 }, { "dmu_tx_dirty_delay", KSTAT_DATA_UINT64 }, { "dmu_tx_dirty_over_max", KSTAT_DATA_UINT64 }, { "dmu_tx_dirty_frees_delay", KSTAT_DATA_UINT64 }, { "dmu_tx_wrlog_delay", KSTAT_DATA_UINT64 }, { "dmu_tx_quota", KSTAT_DATA_UINT64 }, }; static kstat_t *dmu_tx_ksp; dmu_tx_t * dmu_tx_create_dd(dsl_dir_t *dd) { dmu_tx_t *tx = kmem_zalloc(sizeof (dmu_tx_t), KM_SLEEP); tx->tx_dir = dd; if (dd != NULL) tx->tx_pool = dd->dd_pool; list_create(&tx->tx_holds, sizeof (dmu_tx_hold_t), offsetof(dmu_tx_hold_t, txh_node)); list_create(&tx->tx_callbacks, sizeof (dmu_tx_callback_t), offsetof(dmu_tx_callback_t, dcb_node)); tx->tx_start = gethrtime(); return (tx); } dmu_tx_t * dmu_tx_create(objset_t *os) { dmu_tx_t *tx = dmu_tx_create_dd(os->os_dsl_dataset->ds_dir); tx->tx_objset = os; return (tx); } dmu_tx_t * dmu_tx_create_assigned(struct dsl_pool *dp, uint64_t txg) { dmu_tx_t *tx = dmu_tx_create_dd(NULL); TXG_VERIFY(dp->dp_spa, txg); tx->tx_pool = dp; tx->tx_txg = txg; tx->tx_anyobj = TRUE; return (tx); } int dmu_tx_is_syncing(dmu_tx_t *tx) { return (tx->tx_anyobj); } int dmu_tx_private_ok(dmu_tx_t *tx) { return (tx->tx_anyobj); } static dmu_tx_hold_t * dmu_tx_hold_dnode_impl(dmu_tx_t *tx, dnode_t *dn, enum dmu_tx_hold_type type, uint64_t arg1, uint64_t arg2) { dmu_tx_hold_t *txh; if (dn != NULL) { (void) zfs_refcount_add(&dn->dn_holds, tx); if (tx->tx_txg != 0) { mutex_enter(&dn->dn_mtx); /* * dn->dn_assigned_txg == tx->tx_txg doesn't pose a * problem, but there's no way for it to happen (for * now, at least). */ ASSERT(dn->dn_assigned_txg == 0); dn->dn_assigned_txg = tx->tx_txg; (void) zfs_refcount_add(&dn->dn_tx_holds, tx); mutex_exit(&dn->dn_mtx); } } txh = kmem_zalloc(sizeof (dmu_tx_hold_t), KM_SLEEP); txh->txh_tx = tx; txh->txh_dnode = dn; zfs_refcount_create(&txh->txh_space_towrite); zfs_refcount_create(&txh->txh_memory_tohold); txh->txh_type = type; txh->txh_arg1 = arg1; txh->txh_arg2 = arg2; list_insert_tail(&tx->tx_holds, txh); return (txh); } static dmu_tx_hold_t * dmu_tx_hold_object_impl(dmu_tx_t *tx, objset_t *os, uint64_t object, enum dmu_tx_hold_type type, uint64_t arg1, uint64_t arg2) { dnode_t *dn = NULL; dmu_tx_hold_t *txh; int err; if (object != DMU_NEW_OBJECT) { err = dnode_hold(os, object, FTAG, &dn); if (err != 0) { tx->tx_err = err; return (NULL); } } txh = dmu_tx_hold_dnode_impl(tx, dn, type, arg1, arg2); if (dn != NULL) dnode_rele(dn, FTAG); return (txh); } void dmu_tx_add_new_object(dmu_tx_t *tx, dnode_t *dn) { /* * If we're syncing, they can manipulate any object anyhow, and * the hold on the dnode_t can cause problems. */ if (!dmu_tx_is_syncing(tx)) (void) dmu_tx_hold_dnode_impl(tx, dn, THT_NEWOBJECT, 0, 0); } /* * This function reads specified data from disk. The specified data will * be needed to perform the transaction -- i.e, it will be read after * we do dmu_tx_assign(). There are two reasons that we read the data now * (before dmu_tx_assign()): * * 1. Reading it now has potentially better performance. The transaction * has not yet been assigned, so the TXG is not held open, and also the * caller typically has less locks held when calling dmu_tx_hold_*() than * after the transaction has been assigned. This reduces the lock (and txg) * hold times, thus reducing lock contention. * * 2. It is easier for callers (primarily the ZPL) to handle i/o errors * that are detected before they start making changes to the DMU state * (i.e. now). Once the transaction has been assigned, and some DMU * state has been changed, it can be difficult to recover from an i/o * error (e.g. to undo the changes already made in memory at the DMU * layer). Typically code to do so does not exist in the caller -- it * assumes that the data has already been cached and thus i/o errors are * not possible. * * It has been observed that the i/o initiated here can be a performance * problem, and it appears to be optional, because we don't look at the * data which is read. However, removing this read would only serve to * move the work elsewhere (after the dmu_tx_assign()), where it may * have a greater impact on performance (in addition to the impact on * fault tolerance noted above). */ static int dmu_tx_check_ioerr(zio_t *zio, dnode_t *dn, int level, uint64_t blkid) { int err; dmu_buf_impl_t *db; rw_enter(&dn->dn_struct_rwlock, RW_READER); db = dbuf_hold_level(dn, level, blkid, FTAG); rw_exit(&dn->dn_struct_rwlock); if (db == NULL) return (SET_ERROR(EIO)); /* * PARTIAL_FIRST allows caching for uncacheable blocks. It will * be cleared after dmu_buf_will_dirty() call dbuf_read() again. */ err = dbuf_read(db, zio, DB_RF_CANFAIL | DB_RF_NOPREFETCH | (level == 0 ? DB_RF_PARTIAL_FIRST : 0)); dbuf_rele(db, FTAG); return (err); } static void dmu_tx_count_write(dmu_tx_hold_t *txh, uint64_t off, uint64_t len) { dnode_t *dn = txh->txh_dnode; int err = 0; if (len == 0) return; (void) zfs_refcount_add_many(&txh->txh_space_towrite, len, FTAG); if (dn == NULL) return; /* * For i/o error checking, read the blocks that will be needed * to perform the write: the first and last level-0 blocks (if * they are not aligned, i.e. if they are partial-block writes), * and all the level-1 blocks. */ if (dn->dn_maxblkid == 0) { if (off < dn->dn_datablksz && (off > 0 || len < dn->dn_datablksz)) { err = dmu_tx_check_ioerr(NULL, dn, 0, 0); if (err != 0) { txh->txh_tx->tx_err = err; } } } else { zio_t *zio = zio_root(dn->dn_objset->os_spa, NULL, NULL, ZIO_FLAG_CANFAIL); /* first level-0 block */ uint64_t start = off >> dn->dn_datablkshift; if (P2PHASE(off, dn->dn_datablksz) || len < dn->dn_datablksz) { err = dmu_tx_check_ioerr(zio, dn, 0, start); if (err != 0) { txh->txh_tx->tx_err = err; } } /* last level-0 block */ uint64_t end = (off + len - 1) >> dn->dn_datablkshift; if (end != start && end <= dn->dn_maxblkid && P2PHASE(off + len, dn->dn_datablksz)) { err = dmu_tx_check_ioerr(zio, dn, 0, end); if (err != 0) { txh->txh_tx->tx_err = err; } } /* level-1 blocks */ if (dn->dn_nlevels > 1) { int shft = dn->dn_indblkshift - SPA_BLKPTRSHIFT; for (uint64_t i = (start >> shft) + 1; i < end >> shft; i++) { err = dmu_tx_check_ioerr(zio, dn, 1, i); if (err != 0) { txh->txh_tx->tx_err = err; } } } err = zio_wait(zio); if (err != 0) { txh->txh_tx->tx_err = err; } } } static void dmu_tx_count_dnode(dmu_tx_hold_t *txh) { (void) zfs_refcount_add_many(&txh->txh_space_towrite, DNODE_MIN_SIZE, FTAG); } void dmu_tx_hold_write(dmu_tx_t *tx, uint64_t object, uint64_t off, int len) { dmu_tx_hold_t *txh; ASSERT0(tx->tx_txg); ASSERT3U(len, <=, DMU_MAX_ACCESS); ASSERT(len == 0 || UINT64_MAX - off >= len - 1); txh = dmu_tx_hold_object_impl(tx, tx->tx_objset, object, THT_WRITE, off, len); if (txh != NULL) { dmu_tx_count_write(txh, off, len); dmu_tx_count_dnode(txh); } } void dmu_tx_hold_write_by_dnode(dmu_tx_t *tx, dnode_t *dn, uint64_t off, int len) { dmu_tx_hold_t *txh; ASSERT0(tx->tx_txg); ASSERT3U(len, <=, DMU_MAX_ACCESS); ASSERT(len == 0 || UINT64_MAX - off >= len - 1); txh = dmu_tx_hold_dnode_impl(tx, dn, THT_WRITE, off, len); if (txh != NULL) { dmu_tx_count_write(txh, off, len); dmu_tx_count_dnode(txh); } } /* * This function marks the transaction as being a "net free". The end * result is that refquotas will be disabled for this transaction, and * this transaction will be able to use half of the pool space overhead * (see dsl_pool_adjustedsize()). Therefore this function should only * be called for transactions that we expect will not cause a net increase * in the amount of space used (but it's OK if that is occasionally not true). */ void dmu_tx_mark_netfree(dmu_tx_t *tx) { tx->tx_netfree = B_TRUE; } static void dmu_tx_count_free(dmu_tx_hold_t *txh, uint64_t off, uint64_t len) { dmu_tx_t *tx = txh->txh_tx; dnode_t *dn = txh->txh_dnode; int err; ASSERT(tx->tx_txg == 0); if (off >= (dn->dn_maxblkid + 1) * dn->dn_datablksz) return; if (len == DMU_OBJECT_END) len = (dn->dn_maxblkid + 1) * dn->dn_datablksz - off; /* * For i/o error checking, we read the first and last level-0 * blocks if they are not aligned, and all the level-1 blocks. * * Note: dbuf_free_range() assumes that we have not instantiated * any level-0 dbufs that will be completely freed. Therefore we must * exercise care to not read or count the first and last blocks * if they are blocksize-aligned. */ if (dn->dn_datablkshift == 0) { if (off != 0 || len < dn->dn_datablksz) dmu_tx_count_write(txh, 0, dn->dn_datablksz); } else { /* first block will be modified if it is not aligned */ if (!IS_P2ALIGNED(off, 1 << dn->dn_datablkshift)) dmu_tx_count_write(txh, off, 1); /* last block will be modified if it is not aligned */ if (!IS_P2ALIGNED(off + len, 1 << dn->dn_datablkshift)) dmu_tx_count_write(txh, off + len, 1); } /* * Check level-1 blocks. */ if (dn->dn_nlevels > 1) { int shift = dn->dn_datablkshift + dn->dn_indblkshift - SPA_BLKPTRSHIFT; uint64_t start = off >> shift; uint64_t end = (off + len) >> shift; ASSERT(dn->dn_indblkshift != 0); /* * dnode_reallocate() can result in an object with indirect * blocks having an odd data block size. In this case, * just check the single block. */ if (dn->dn_datablkshift == 0) start = end = 0; zio_t *zio = zio_root(tx->tx_pool->dp_spa, NULL, NULL, ZIO_FLAG_CANFAIL); for (uint64_t i = start; i <= end; i++) { uint64_t ibyte = i << shift; err = dnode_next_offset(dn, 0, &ibyte, 2, 1, 0); i = ibyte >> shift; if (err == ESRCH || i > end) break; if (err != 0) { tx->tx_err = err; (void) zio_wait(zio); return; } (void) zfs_refcount_add_many(&txh->txh_memory_tohold, 1 << dn->dn_indblkshift, FTAG); err = dmu_tx_check_ioerr(zio, dn, 1, i); if (err != 0) { tx->tx_err = err; (void) zio_wait(zio); return; } } err = zio_wait(zio); if (err != 0) { tx->tx_err = err; return; } } } void dmu_tx_hold_free(dmu_tx_t *tx, uint64_t object, uint64_t off, uint64_t len) { dmu_tx_hold_t *txh; txh = dmu_tx_hold_object_impl(tx, tx->tx_objset, object, THT_FREE, off, len); if (txh != NULL) { dmu_tx_count_dnode(txh); dmu_tx_count_free(txh, off, len); } } void dmu_tx_hold_free_by_dnode(dmu_tx_t *tx, dnode_t *dn, uint64_t off, uint64_t len) { dmu_tx_hold_t *txh; txh = dmu_tx_hold_dnode_impl(tx, dn, THT_FREE, off, len); if (txh != NULL) { dmu_tx_count_dnode(txh); dmu_tx_count_free(txh, off, len); } } static void dmu_tx_count_clone(dmu_tx_hold_t *txh, uint64_t off, uint64_t len) { /* * Reuse dmu_tx_count_free(), it does exactly what we need for clone. */ dmu_tx_count_free(txh, off, len); } void dmu_tx_hold_clone_by_dnode(dmu_tx_t *tx, dnode_t *dn, uint64_t off, int len) { dmu_tx_hold_t *txh; ASSERT0(tx->tx_txg); ASSERT(len == 0 || UINT64_MAX - off >= len - 1); txh = dmu_tx_hold_dnode_impl(tx, dn, THT_CLONE, off, len); if (txh != NULL) { dmu_tx_count_dnode(txh); dmu_tx_count_clone(txh, off, len); } } static void dmu_tx_hold_zap_impl(dmu_tx_hold_t *txh, const char *name) { dmu_tx_t *tx = txh->txh_tx; dnode_t *dn = txh->txh_dnode; int err; extern int zap_micro_max_size; ASSERT(tx->tx_txg == 0); dmu_tx_count_dnode(txh); /* * Modifying a almost-full microzap is around the worst case (128KB) * * If it is a fat zap, the worst case would be 7*16KB=112KB: * - 3 blocks overwritten: target leaf, ptrtbl block, header block * - 4 new blocks written if adding: * - 2 blocks for possibly split leaves, * - 2 grown ptrtbl blocks */ (void) zfs_refcount_add_many(&txh->txh_space_towrite, zap_micro_max_size, FTAG); if (dn == NULL) return; ASSERT3U(DMU_OT_BYTESWAP(dn->dn_type), ==, DMU_BSWAP_ZAP); if (dn->dn_maxblkid == 0 || name == NULL) { /* * This is a microzap (only one block), or we don't know * the name. Check the first block for i/o errors. */ err = dmu_tx_check_ioerr(NULL, dn, 0, 0); if (err != 0) { tx->tx_err = err; } } else { /* * Access the name so that we'll check for i/o errors to * the leaf blocks, etc. We ignore ENOENT, as this name * may not yet exist. */ err = zap_lookup_by_dnode(dn, name, 8, 0, NULL); if (err == EIO || err == ECKSUM || err == ENXIO) { tx->tx_err = err; } } } void dmu_tx_hold_zap(dmu_tx_t *tx, uint64_t object, int add, const char *name) { dmu_tx_hold_t *txh; ASSERT0(tx->tx_txg); txh = dmu_tx_hold_object_impl(tx, tx->tx_objset, object, THT_ZAP, add, (uintptr_t)name); if (txh != NULL) dmu_tx_hold_zap_impl(txh, name); } void dmu_tx_hold_zap_by_dnode(dmu_tx_t *tx, dnode_t *dn, int add, const char *name) { dmu_tx_hold_t *txh; ASSERT0(tx->tx_txg); ASSERT(dn != NULL); txh = dmu_tx_hold_dnode_impl(tx, dn, THT_ZAP, add, (uintptr_t)name); if (txh != NULL) dmu_tx_hold_zap_impl(txh, name); } void dmu_tx_hold_bonus(dmu_tx_t *tx, uint64_t object) { dmu_tx_hold_t *txh; ASSERT(tx->tx_txg == 0); txh = dmu_tx_hold_object_impl(tx, tx->tx_objset, object, THT_BONUS, 0, 0); if (txh) dmu_tx_count_dnode(txh); } void dmu_tx_hold_bonus_by_dnode(dmu_tx_t *tx, dnode_t *dn) { dmu_tx_hold_t *txh; ASSERT0(tx->tx_txg); txh = dmu_tx_hold_dnode_impl(tx, dn, THT_BONUS, 0, 0); if (txh) dmu_tx_count_dnode(txh); } void dmu_tx_hold_space(dmu_tx_t *tx, uint64_t space) { dmu_tx_hold_t *txh; ASSERT(tx->tx_txg == 0); txh = dmu_tx_hold_object_impl(tx, tx->tx_objset, DMU_NEW_OBJECT, THT_SPACE, space, 0); if (txh) { (void) zfs_refcount_add_many( &txh->txh_space_towrite, space, FTAG); } } #ifdef ZFS_DEBUG void dmu_tx_dirty_buf(dmu_tx_t *tx, dmu_buf_impl_t *db) { boolean_t match_object = B_FALSE; boolean_t match_offset = B_FALSE; DB_DNODE_ENTER(db); dnode_t *dn = DB_DNODE(db); ASSERT(tx->tx_txg != 0); ASSERT(tx->tx_objset == NULL || dn->dn_objset == tx->tx_objset); ASSERT3U(dn->dn_object, ==, db->db.db_object); if (tx->tx_anyobj) { DB_DNODE_EXIT(db); return; } /* XXX No checking on the meta dnode for now */ if (db->db.db_object == DMU_META_DNODE_OBJECT) { DB_DNODE_EXIT(db); return; } for (dmu_tx_hold_t *txh = list_head(&tx->tx_holds); txh != NULL; txh = list_next(&tx->tx_holds, txh)) { ASSERT3U(dn->dn_assigned_txg, ==, tx->tx_txg); if (txh->txh_dnode == dn && txh->txh_type != THT_NEWOBJECT) match_object = TRUE; if (txh->txh_dnode == NULL || txh->txh_dnode == dn) { int datablkshift = dn->dn_datablkshift ? dn->dn_datablkshift : SPA_MAXBLOCKSHIFT; int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT; int shift = datablkshift + epbs * db->db_level; uint64_t beginblk = shift >= 64 ? 0 : (txh->txh_arg1 >> shift); uint64_t endblk = shift >= 64 ? 0 : ((txh->txh_arg1 + txh->txh_arg2 - 1) >> shift); uint64_t blkid = db->db_blkid; /* XXX txh_arg2 better not be zero... */ dprintf("found txh type %x beginblk=%llx endblk=%llx\n", txh->txh_type, (u_longlong_t)beginblk, (u_longlong_t)endblk); switch (txh->txh_type) { case THT_WRITE: if (blkid >= beginblk && blkid <= endblk) match_offset = TRUE; /* * We will let this hold work for the bonus * or spill buffer so that we don't need to * hold it when creating a new object. */ if (blkid == DMU_BONUS_BLKID || blkid == DMU_SPILL_BLKID) match_offset = TRUE; /* * They might have to increase nlevels, * thus dirtying the new TLIBs. Or the * might have to change the block size, * thus dirying the new lvl=0 blk=0. */ if (blkid == 0) match_offset = TRUE; break; case THT_FREE: /* * We will dirty all the level 1 blocks in * the free range and perhaps the first and * last level 0 block. */ if (blkid >= beginblk && (blkid <= endblk || txh->txh_arg2 == DMU_OBJECT_END)) match_offset = TRUE; break; case THT_SPILL: if (blkid == DMU_SPILL_BLKID) match_offset = TRUE; break; case THT_BONUS: if (blkid == DMU_BONUS_BLKID) match_offset = TRUE; break; case THT_ZAP: match_offset = TRUE; break; case THT_NEWOBJECT: match_object = TRUE; break; case THT_CLONE: if (blkid >= beginblk && blkid <= endblk) match_offset = TRUE; break; default: cmn_err(CE_PANIC, "bad txh_type %d", txh->txh_type); } } if (match_object && match_offset) { DB_DNODE_EXIT(db); return; } } DB_DNODE_EXIT(db); panic("dirtying dbuf obj=%llx lvl=%u blkid=%llx but not tx_held\n", (u_longlong_t)db->db.db_object, db->db_level, (u_longlong_t)db->db_blkid); } #endif /* * If we can't do 10 iops, something is wrong. Let us go ahead * and hit zfs_dirty_data_max. */ static const hrtime_t zfs_delay_max_ns = 100 * MICROSEC; /* 100 milliseconds */ /* * We delay transactions when we've determined that the backend storage * isn't able to accommodate the rate of incoming writes. * * If there is already a transaction waiting, we delay relative to when * that transaction finishes waiting. This way the calculated min_time * is independent of the number of threads concurrently executing * transactions. * * If we are the only waiter, wait relative to when the transaction * started, rather than the current time. This credits the transaction for * "time already served", e.g. reading indirect blocks. * * The minimum time for a transaction to take is calculated as: * min_time = scale * (dirty - min) / (max - dirty) * min_time is then capped at zfs_delay_max_ns. * * The delay has two degrees of freedom that can be adjusted via tunables. * The percentage of dirty data at which we start to delay is defined by * zfs_delay_min_dirty_percent. This should typically be at or above * zfs_vdev_async_write_active_max_dirty_percent so that we only start to * delay after writing at full speed has failed to keep up with the incoming * write rate. The scale of the curve is defined by zfs_delay_scale. Roughly * speaking, this variable determines the amount of delay at the midpoint of * the curve. * * delay * 10ms +-------------------------------------------------------------*+ * | *| * 9ms + *+ * | *| * 8ms + *+ * | * | * 7ms + * + * | * | * 6ms + * + * | * | * 5ms + * + * | * | * 4ms + * + * | * | * 3ms + * + * | * | * 2ms + (midpoint) * + * | | ** | * 1ms + v *** + * | zfs_delay_scale ----------> ******** | * 0 +-------------------------------------*********----------------+ * 0% <- zfs_dirty_data_max -> 100% * * Note that since the delay is added to the outstanding time remaining on the * most recent transaction, the delay is effectively the inverse of IOPS. * Here the midpoint of 500us translates to 2000 IOPS. The shape of the curve * was chosen such that small changes in the amount of accumulated dirty data * in the first 3/4 of the curve yield relatively small differences in the * amount of delay. * * The effects can be easier to understand when the amount of delay is * represented on a log scale: * * delay * 100ms +-------------------------------------------------------------++ * + + * | | * + *+ * 10ms + *+ * + ** + * | (midpoint) ** | * + | ** + * 1ms + v **** + * + zfs_delay_scale ----------> ***** + * | **** | * + **** + * 100us + ** + * + * + * | * | * + * + * 10us + * + * + + * | | * + + * +--------------------------------------------------------------+ * 0% <- zfs_dirty_data_max -> 100% * * Note here that only as the amount of dirty data approaches its limit does * the delay start to increase rapidly. The goal of a properly tuned system * should be to keep the amount of dirty data out of that range by first * ensuring that the appropriate limits are set for the I/O scheduler to reach * optimal throughput on the backend storage, and then by changing the value * of zfs_delay_scale to increase the steepness of the curve. */ static void dmu_tx_delay(dmu_tx_t *tx, uint64_t dirty) { dsl_pool_t *dp = tx->tx_pool; uint64_t delay_min_bytes, wrlog; hrtime_t wakeup, tx_time = 0, now; /* Calculate minimum transaction time for the dirty data amount. */ delay_min_bytes = zfs_dirty_data_max * zfs_delay_min_dirty_percent / 100; if (dirty > delay_min_bytes) { /* * The caller has already waited until we are under the max. * We make them pass us the amount of dirty data so we don't * have to handle the case of it being >= the max, which * could cause a divide-by-zero if it's == the max. */ ASSERT3U(dirty, <, zfs_dirty_data_max); tx_time = zfs_delay_scale * (dirty - delay_min_bytes) / (zfs_dirty_data_max - dirty); } /* Calculate minimum transaction time for the TX_WRITE log size. */ wrlog = aggsum_upper_bound(&dp->dp_wrlog_total); delay_min_bytes = zfs_wrlog_data_max * zfs_delay_min_dirty_percent / 100; if (wrlog >= zfs_wrlog_data_max) { tx_time = zfs_delay_max_ns; } else if (wrlog > delay_min_bytes) { tx_time = MAX(zfs_delay_scale * (wrlog - delay_min_bytes) / (zfs_wrlog_data_max - wrlog), tx_time); } if (tx_time == 0) return; tx_time = MIN(tx_time, zfs_delay_max_ns); now = gethrtime(); if (now > tx->tx_start + tx_time) return; DTRACE_PROBE3(delay__mintime, dmu_tx_t *, tx, uint64_t, dirty, uint64_t, tx_time); mutex_enter(&dp->dp_lock); wakeup = MAX(tx->tx_start + tx_time, dp->dp_last_wakeup + tx_time); dp->dp_last_wakeup = wakeup; mutex_exit(&dp->dp_lock); zfs_sleep_until(wakeup); } /* * This routine attempts to assign the transaction to a transaction group. * To do so, we must determine if there is sufficient free space on disk. * * If this is a "netfree" transaction (i.e. we called dmu_tx_mark_netfree() * on it), then it is assumed that there is sufficient free space, * unless there's insufficient slop space in the pool (see the comment * above spa_slop_shift in spa_misc.c). * * If it is not a "netfree" transaction, then if the data already on disk * is over the allowed usage (e.g. quota), this will fail with EDQUOT or * ENOSPC. Otherwise, if the current rough estimate of pending changes, * plus the rough estimate of this transaction's changes, may exceed the * allowed usage, then this will fail with ERESTART, which will cause the * caller to wait for the pending changes to be written to disk (by waiting * for the next TXG to open), and then check the space usage again. * * The rough estimate of pending changes is comprised of the sum of: * * - this transaction's holds' txh_space_towrite * * - dd_tempreserved[], which is the sum of in-flight transactions' * holds' txh_space_towrite (i.e. those transactions that have called * dmu_tx_assign() but not yet called dmu_tx_commit()). * * - dd_space_towrite[], which is the amount of dirtied dbufs. * * Note that all of these values are inflated by spa_get_worst_case_asize(), * which means that we may get ERESTART well before we are actually in danger * of running out of space, but this also mitigates any small inaccuracies * in the rough estimate (e.g. txh_space_towrite doesn't take into account * indirect blocks, and dd_space_towrite[] doesn't take into account changes * to the MOS). * * Note that due to this algorithm, it is possible to exceed the allowed * usage by one transaction. Also, as we approach the allowed usage, * we will allow a very limited amount of changes into each TXG, thus * decreasing performance. */ static int dmu_tx_try_assign(dmu_tx_t *tx, uint64_t txg_how) { spa_t *spa = tx->tx_pool->dp_spa; ASSERT0(tx->tx_txg); if (tx->tx_err) { DMU_TX_STAT_BUMP(dmu_tx_error); return (tx->tx_err); } if (spa_suspended(spa)) { DMU_TX_STAT_BUMP(dmu_tx_suspended); /* * If the user has indicated a blocking failure mode * then return ERESTART which will block in dmu_tx_wait(). * Otherwise, return EIO so that an error can get * propagated back to the VOP calls. * * Note that we always honor the txg_how flag regardless * of the failuremode setting. */ if (spa_get_failmode(spa) == ZIO_FAILURE_MODE_CONTINUE && !(txg_how & TXG_WAIT)) return (SET_ERROR(EIO)); return (SET_ERROR(ERESTART)); } if (!tx->tx_dirty_delayed && dsl_pool_need_wrlog_delay(tx->tx_pool)) { tx->tx_wait_dirty = B_TRUE; DMU_TX_STAT_BUMP(dmu_tx_wrlog_delay); return (SET_ERROR(ERESTART)); } if (!tx->tx_dirty_delayed && dsl_pool_need_dirty_delay(tx->tx_pool)) { tx->tx_wait_dirty = B_TRUE; DMU_TX_STAT_BUMP(dmu_tx_dirty_delay); return (SET_ERROR(ERESTART)); } tx->tx_txg = txg_hold_open(tx->tx_pool, &tx->tx_txgh); tx->tx_needassign_txh = NULL; /* * NB: No error returns are allowed after txg_hold_open, but * before processing the dnode holds, due to the * dmu_tx_unassign() logic. */ uint64_t towrite = 0; uint64_t tohold = 0; for (dmu_tx_hold_t *txh = list_head(&tx->tx_holds); txh != NULL; txh = list_next(&tx->tx_holds, txh)) { dnode_t *dn = txh->txh_dnode; if (dn != NULL) { /* * This thread can't hold the dn_struct_rwlock * while assigning the tx, because this can lead to * deadlock. Specifically, if this dnode is already * assigned to an earlier txg, this thread may need * to wait for that txg to sync (the ERESTART case * below). The other thread that has assigned this * dnode to an earlier txg prevents this txg from * syncing until its tx can complete (calling * dmu_tx_commit()), but it may need to acquire the * dn_struct_rwlock to do so (e.g. via * dmu_buf_hold*()). * * Note that this thread can't hold the lock for * read either, but the rwlock doesn't record * enough information to make that assertion. */ ASSERT(!RW_WRITE_HELD(&dn->dn_struct_rwlock)); mutex_enter(&dn->dn_mtx); if (dn->dn_assigned_txg == tx->tx_txg - 1) { mutex_exit(&dn->dn_mtx); tx->tx_needassign_txh = txh; DMU_TX_STAT_BUMP(dmu_tx_group); return (SET_ERROR(ERESTART)); } if (dn->dn_assigned_txg == 0) dn->dn_assigned_txg = tx->tx_txg; ASSERT3U(dn->dn_assigned_txg, ==, tx->tx_txg); (void) zfs_refcount_add(&dn->dn_tx_holds, tx); mutex_exit(&dn->dn_mtx); } towrite += zfs_refcount_count(&txh->txh_space_towrite); tohold += zfs_refcount_count(&txh->txh_memory_tohold); } /* needed allocation: worst-case estimate of write space */ uint64_t asize = spa_get_worst_case_asize(tx->tx_pool->dp_spa, towrite); /* calculate memory footprint estimate */ uint64_t memory = towrite + tohold; if (tx->tx_dir != NULL && asize != 0) { int err = dsl_dir_tempreserve_space(tx->tx_dir, memory, asize, tx->tx_netfree, &tx->tx_tempreserve_cookie, tx); if (err != 0) return (err); } DMU_TX_STAT_BUMP(dmu_tx_assigned); return (0); } static void dmu_tx_unassign(dmu_tx_t *tx) { if (tx->tx_txg == 0) return; txg_rele_to_quiesce(&tx->tx_txgh); /* * Walk the transaction's hold list, removing the hold on the * associated dnode, and notifying waiters if the refcount drops to 0. */ for (dmu_tx_hold_t *txh = list_head(&tx->tx_holds); txh && txh != tx->tx_needassign_txh; txh = list_next(&tx->tx_holds, txh)) { dnode_t *dn = txh->txh_dnode; if (dn == NULL) continue; mutex_enter(&dn->dn_mtx); ASSERT3U(dn->dn_assigned_txg, ==, tx->tx_txg); if (zfs_refcount_remove(&dn->dn_tx_holds, tx) == 0) { dn->dn_assigned_txg = 0; cv_broadcast(&dn->dn_notxholds); } mutex_exit(&dn->dn_mtx); } txg_rele_to_sync(&tx->tx_txgh); tx->tx_lasttried_txg = tx->tx_txg; tx->tx_txg = 0; } /* * Assign tx to a transaction group; txg_how is a bitmask: * * If TXG_WAIT is set and the currently open txg is full, this function * will wait until there's a new txg. This should be used when no locks * are being held. With this bit set, this function will only fail if * we're truly out of space (or over quota). * * If TXG_WAIT is *not* set and we can't assign into the currently open * txg without blocking, this function will return immediately with * ERESTART. This should be used whenever locks are being held. On an * ERESTART error, the caller should drop all locks, call dmu_tx_wait(), * and try again. * * If TXG_NOTHROTTLE is set, this indicates that this tx should not be * delayed due on the ZFS Write Throttle (see comments in dsl_pool.c for * details on the throttle). This is used by the VFS operations, after * they have already called dmu_tx_wait() (though most likely on a * different tx). * * It is guaranteed that subsequent successful calls to dmu_tx_assign() * will assign the tx to monotonically increasing txgs. Of course this is * not strong monotonicity, because the same txg can be returned multiple * times in a row. This guarantee holds both for subsequent calls from * one thread and for multiple threads. For example, it is impossible to * observe the following sequence of events: * * Thread 1 Thread 2 * * dmu_tx_assign(T1, ...) * 1 <- dmu_tx_get_txg(T1) * dmu_tx_assign(T2, ...) * 2 <- dmu_tx_get_txg(T2) * dmu_tx_assign(T3, ...) * 1 <- dmu_tx_get_txg(T3) */ int dmu_tx_assign(dmu_tx_t *tx, uint64_t txg_how) { int err; ASSERT(tx->tx_txg == 0); ASSERT0(txg_how & ~(TXG_WAIT | TXG_NOTHROTTLE)); ASSERT(!dsl_pool_sync_context(tx->tx_pool)); /* If we might wait, we must not hold the config lock. */ IMPLY((txg_how & TXG_WAIT), !dsl_pool_config_held(tx->tx_pool)); if ((txg_how & TXG_NOTHROTTLE)) tx->tx_dirty_delayed = B_TRUE; while ((err = dmu_tx_try_assign(tx, txg_how)) != 0) { dmu_tx_unassign(tx); if (err != ERESTART || !(txg_how & TXG_WAIT)) return (err); dmu_tx_wait(tx); } txg_rele_to_quiesce(&tx->tx_txgh); return (0); } void dmu_tx_wait(dmu_tx_t *tx) { spa_t *spa = tx->tx_pool->dp_spa; dsl_pool_t *dp = tx->tx_pool; hrtime_t before; ASSERT(tx->tx_txg == 0); ASSERT(!dsl_pool_config_held(tx->tx_pool)); before = gethrtime(); if (tx->tx_wait_dirty) { uint64_t dirty; /* * dmu_tx_try_assign() has determined that we need to wait * because we've consumed much or all of the dirty buffer * space. */ mutex_enter(&dp->dp_lock); if (dp->dp_dirty_total >= zfs_dirty_data_max) DMU_TX_STAT_BUMP(dmu_tx_dirty_over_max); while (dp->dp_dirty_total >= zfs_dirty_data_max) cv_wait(&dp->dp_spaceavail_cv, &dp->dp_lock); dirty = dp->dp_dirty_total; mutex_exit(&dp->dp_lock); dmu_tx_delay(tx, dirty); tx->tx_wait_dirty = B_FALSE; /* * Note: setting tx_dirty_delayed only has effect if the * caller used TX_WAIT. Otherwise they are going to * destroy this tx and try again. The common case, * zfs_write(), uses TX_WAIT. */ tx->tx_dirty_delayed = B_TRUE; } else if (spa_suspended(spa) || tx->tx_lasttried_txg == 0) { /* * If the pool is suspended we need to wait until it * is resumed. Note that it's possible that the pool * has become active after this thread has tried to * obtain a tx. If that's the case then tx_lasttried_txg * would not have been set. */ txg_wait_synced(dp, spa_last_synced_txg(spa) + 1); } else if (tx->tx_needassign_txh) { dnode_t *dn = tx->tx_needassign_txh->txh_dnode; mutex_enter(&dn->dn_mtx); while (dn->dn_assigned_txg == tx->tx_lasttried_txg - 1) cv_wait(&dn->dn_notxholds, &dn->dn_mtx); mutex_exit(&dn->dn_mtx); tx->tx_needassign_txh = NULL; } else { /* * If we have a lot of dirty data just wait until we sync * out a TXG at which point we'll hopefully have synced * a portion of the changes. */ txg_wait_synced(dp, spa_last_synced_txg(spa) + 1); } spa_tx_assign_add_nsecs(spa, gethrtime() - before); } static void dmu_tx_destroy(dmu_tx_t *tx) { dmu_tx_hold_t *txh; while ((txh = list_head(&tx->tx_holds)) != NULL) { dnode_t *dn = txh->txh_dnode; list_remove(&tx->tx_holds, txh); zfs_refcount_destroy_many(&txh->txh_space_towrite, zfs_refcount_count(&txh->txh_space_towrite)); zfs_refcount_destroy_many(&txh->txh_memory_tohold, zfs_refcount_count(&txh->txh_memory_tohold)); kmem_free(txh, sizeof (dmu_tx_hold_t)); if (dn != NULL) dnode_rele(dn, tx); } list_destroy(&tx->tx_callbacks); list_destroy(&tx->tx_holds); kmem_free(tx, sizeof (dmu_tx_t)); } void dmu_tx_commit(dmu_tx_t *tx) { ASSERT(tx->tx_txg != 0); /* * Go through the transaction's hold list and remove holds on * associated dnodes, notifying waiters if no holds remain. */ for (dmu_tx_hold_t *txh = list_head(&tx->tx_holds); txh != NULL; txh = list_next(&tx->tx_holds, txh)) { dnode_t *dn = txh->txh_dnode; if (dn == NULL) continue; mutex_enter(&dn->dn_mtx); ASSERT3U(dn->dn_assigned_txg, ==, tx->tx_txg); if (zfs_refcount_remove(&dn->dn_tx_holds, tx) == 0) { dn->dn_assigned_txg = 0; cv_broadcast(&dn->dn_notxholds); } mutex_exit(&dn->dn_mtx); } if (tx->tx_tempreserve_cookie) dsl_dir_tempreserve_clear(tx->tx_tempreserve_cookie, tx); if (!list_is_empty(&tx->tx_callbacks)) txg_register_callbacks(&tx->tx_txgh, &tx->tx_callbacks); if (tx->tx_anyobj == FALSE) txg_rele_to_sync(&tx->tx_txgh); dmu_tx_destroy(tx); } void dmu_tx_abort(dmu_tx_t *tx) { ASSERT(tx->tx_txg == 0); /* * Call any registered callbacks with an error code. */ if (!list_is_empty(&tx->tx_callbacks)) dmu_tx_do_callbacks(&tx->tx_callbacks, SET_ERROR(ECANCELED)); dmu_tx_destroy(tx); } uint64_t dmu_tx_get_txg(dmu_tx_t *tx) { ASSERT(tx->tx_txg != 0); return (tx->tx_txg); } dsl_pool_t * dmu_tx_pool(dmu_tx_t *tx) { ASSERT(tx->tx_pool != NULL); return (tx->tx_pool); } void dmu_tx_callback_register(dmu_tx_t *tx, dmu_tx_callback_func_t *func, void *data) { dmu_tx_callback_t *dcb; dcb = kmem_alloc(sizeof (dmu_tx_callback_t), KM_SLEEP); dcb->dcb_func = func; dcb->dcb_data = data; list_insert_tail(&tx->tx_callbacks, dcb); } /* * Call all the commit callbacks on a list, with a given error code. */ void dmu_tx_do_callbacks(list_t *cb_list, int error) { dmu_tx_callback_t *dcb; while ((dcb = list_tail(cb_list)) != NULL) { list_remove(cb_list, dcb); dcb->dcb_func(dcb->dcb_data, error); kmem_free(dcb, sizeof (dmu_tx_callback_t)); } } /* * Interface to hold a bunch of attributes. * used for creating new files. * attrsize is the total size of all attributes * to be added during object creation * * For updating/adding a single attribute dmu_tx_hold_sa() should be used. */ /* * hold necessary attribute name for attribute registration. * should be a very rare case where this is needed. If it does * happen it would only happen on the first write to the file system. */ static void dmu_tx_sa_registration_hold(sa_os_t *sa, dmu_tx_t *tx) { if (!sa->sa_need_attr_registration) return; for (int i = 0; i != sa->sa_num_attrs; i++) { if (!sa->sa_attr_table[i].sa_registered) { if (sa->sa_reg_attr_obj) dmu_tx_hold_zap(tx, sa->sa_reg_attr_obj, B_TRUE, sa->sa_attr_table[i].sa_name); else dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, B_TRUE, sa->sa_attr_table[i].sa_name); } } } void dmu_tx_hold_spill(dmu_tx_t *tx, uint64_t object) { dmu_tx_hold_t *txh; txh = dmu_tx_hold_object_impl(tx, tx->tx_objset, object, THT_SPILL, 0, 0); if (txh != NULL) (void) zfs_refcount_add_many(&txh->txh_space_towrite, SPA_OLD_MAXBLOCKSIZE, FTAG); } void dmu_tx_hold_sa_create(dmu_tx_t *tx, int attrsize) { sa_os_t *sa = tx->tx_objset->os_sa; dmu_tx_hold_bonus(tx, DMU_NEW_OBJECT); if (tx->tx_objset->os_sa->sa_master_obj == 0) return; if (tx->tx_objset->os_sa->sa_layout_attr_obj) { dmu_tx_hold_zap(tx, sa->sa_layout_attr_obj, B_TRUE, NULL); } else { dmu_tx_hold_zap(tx, sa->sa_master_obj, B_TRUE, SA_LAYOUTS); dmu_tx_hold_zap(tx, sa->sa_master_obj, B_TRUE, SA_REGISTRY); dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, B_TRUE, NULL); dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, B_TRUE, NULL); } dmu_tx_sa_registration_hold(sa, tx); if (attrsize <= DN_OLD_MAX_BONUSLEN && !sa->sa_force_spill) return; (void) dmu_tx_hold_object_impl(tx, tx->tx_objset, DMU_NEW_OBJECT, THT_SPILL, 0, 0); } /* * Hold SA attribute * * dmu_tx_hold_sa(dmu_tx_t *tx, sa_handle_t *, attribute, add, size) * * variable_size is the total size of all variable sized attributes * passed to this function. It is not the total size of all * variable size attributes that *may* exist on this object. */ void dmu_tx_hold_sa(dmu_tx_t *tx, sa_handle_t *hdl, boolean_t may_grow) { uint64_t object; sa_os_t *sa = tx->tx_objset->os_sa; ASSERT(hdl != NULL); object = sa_handle_object(hdl); dmu_buf_impl_t *db = (dmu_buf_impl_t *)hdl->sa_bonus; DB_DNODE_ENTER(db); dmu_tx_hold_bonus_by_dnode(tx, DB_DNODE(db)); DB_DNODE_EXIT(db); if (tx->tx_objset->os_sa->sa_master_obj == 0) return; if (tx->tx_objset->os_sa->sa_reg_attr_obj == 0 || tx->tx_objset->os_sa->sa_layout_attr_obj == 0) { dmu_tx_hold_zap(tx, sa->sa_master_obj, B_TRUE, SA_LAYOUTS); dmu_tx_hold_zap(tx, sa->sa_master_obj, B_TRUE, SA_REGISTRY); dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, B_TRUE, NULL); dmu_tx_hold_zap(tx, DMU_NEW_OBJECT, B_TRUE, NULL); } dmu_tx_sa_registration_hold(sa, tx); if (may_grow && tx->tx_objset->os_sa->sa_layout_attr_obj) dmu_tx_hold_zap(tx, sa->sa_layout_attr_obj, B_TRUE, NULL); if (sa->sa_force_spill || may_grow || hdl->sa_spill) { ASSERT(tx->tx_txg == 0); dmu_tx_hold_spill(tx, object); } else { dnode_t *dn; DB_DNODE_ENTER(db); dn = DB_DNODE(db); if (dn->dn_have_spill) { ASSERT(tx->tx_txg == 0); dmu_tx_hold_spill(tx, object); } DB_DNODE_EXIT(db); } } void dmu_tx_init(void) { dmu_tx_ksp = kstat_create("zfs", 0, "dmu_tx", "misc", KSTAT_TYPE_NAMED, sizeof (dmu_tx_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL); if (dmu_tx_ksp != NULL) { dmu_tx_ksp->ks_data = &dmu_tx_stats; kstat_install(dmu_tx_ksp); } } void dmu_tx_fini(void) { if (dmu_tx_ksp != NULL) { kstat_delete(dmu_tx_ksp); dmu_tx_ksp = NULL; } } #if defined(_KERNEL) EXPORT_SYMBOL(dmu_tx_create); EXPORT_SYMBOL(dmu_tx_hold_write); EXPORT_SYMBOL(dmu_tx_hold_write_by_dnode); EXPORT_SYMBOL(dmu_tx_hold_free); EXPORT_SYMBOL(dmu_tx_hold_free_by_dnode); EXPORT_SYMBOL(dmu_tx_hold_zap); EXPORT_SYMBOL(dmu_tx_hold_zap_by_dnode); EXPORT_SYMBOL(dmu_tx_hold_bonus); EXPORT_SYMBOL(dmu_tx_hold_bonus_by_dnode); EXPORT_SYMBOL(dmu_tx_abort); EXPORT_SYMBOL(dmu_tx_assign); EXPORT_SYMBOL(dmu_tx_wait); EXPORT_SYMBOL(dmu_tx_commit); EXPORT_SYMBOL(dmu_tx_mark_netfree); EXPORT_SYMBOL(dmu_tx_get_txg); EXPORT_SYMBOL(dmu_tx_callback_register); EXPORT_SYMBOL(dmu_tx_do_callbacks); EXPORT_SYMBOL(dmu_tx_hold_spill); EXPORT_SYMBOL(dmu_tx_hold_sa_create); EXPORT_SYMBOL(dmu_tx_hold_sa); #endif