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-rw-r--r--module/zfs/bptree.c303
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diff --git a/module/zfs/bptree.c b/module/zfs/bptree.c
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+/*
+ * 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) 2011, 2018 by Delphix. All rights reserved.
+ */
+
+#include <sys/arc.h>
+#include <sys/bptree.h>
+#include <sys/dmu.h>
+#include <sys/dmu_objset.h>
+#include <sys/dmu_tx.h>
+#include <sys/dmu_traverse.h>
+#include <sys/dsl_dataset.h>
+#include <sys/dsl_dir.h>
+#include <sys/dsl_pool.h>
+#include <sys/dnode.h>
+#include <sys/spa.h>
+
+/*
+ * A bptree is a queue of root block pointers from destroyed datasets. When a
+ * dataset is destroyed its root block pointer is put on the end of the pool's
+ * bptree queue so the dataset's blocks can be freed asynchronously by
+ * dsl_scan_sync. This allows the delete operation to finish without traversing
+ * all the dataset's blocks.
+ *
+ * Note that while bt_begin and bt_end are only ever incremented in this code,
+ * they are effectively reset to 0 every time the entire bptree is freed because
+ * the bptree's object is destroyed and re-created.
+ */
+
+struct bptree_args {
+ bptree_phys_t *ba_phys; /* data in bonus buffer, dirtied if freeing */
+ boolean_t ba_free; /* true if freeing during traversal */
+
+ bptree_itor_t *ba_func; /* function to call for each blockpointer */
+ void *ba_arg; /* caller supplied argument to ba_func */
+ dmu_tx_t *ba_tx; /* caller supplied tx, NULL if not freeing */
+} bptree_args_t;
+
+uint64_t
+bptree_alloc(objset_t *os, dmu_tx_t *tx)
+{
+ uint64_t obj;
+ dmu_buf_t *db;
+ bptree_phys_t *bt;
+
+ obj = dmu_object_alloc(os, DMU_OTN_UINT64_METADATA,
+ SPA_OLD_MAXBLOCKSIZE, DMU_OTN_UINT64_METADATA,
+ sizeof (bptree_phys_t), tx);
+
+ /*
+ * Bonus buffer contents are already initialized to 0, but for
+ * readability we make it explicit.
+ */
+ VERIFY3U(0, ==, dmu_bonus_hold(os, obj, FTAG, &db));
+ dmu_buf_will_dirty(db, tx);
+ bt = db->db_data;
+ bt->bt_begin = 0;
+ bt->bt_end = 0;
+ bt->bt_bytes = 0;
+ bt->bt_comp = 0;
+ bt->bt_uncomp = 0;
+ dmu_buf_rele(db, FTAG);
+
+ return (obj);
+}
+
+int
+bptree_free(objset_t *os, uint64_t obj, dmu_tx_t *tx)
+{
+ dmu_buf_t *db;
+ bptree_phys_t *bt;
+
+ VERIFY3U(0, ==, dmu_bonus_hold(os, obj, FTAG, &db));
+ bt = db->db_data;
+ ASSERT3U(bt->bt_begin, ==, bt->bt_end);
+ ASSERT0(bt->bt_bytes);
+ ASSERT0(bt->bt_comp);
+ ASSERT0(bt->bt_uncomp);
+ dmu_buf_rele(db, FTAG);
+
+ return (dmu_object_free(os, obj, tx));
+}
+
+boolean_t
+bptree_is_empty(objset_t *os, uint64_t obj)
+{
+ dmu_buf_t *db;
+ bptree_phys_t *bt;
+ boolean_t rv;
+
+ VERIFY0(dmu_bonus_hold(os, obj, FTAG, &db));
+ bt = db->db_data;
+ rv = (bt->bt_begin == bt->bt_end);
+ dmu_buf_rele(db, FTAG);
+ return (rv);
+}
+
+void
+bptree_add(objset_t *os, uint64_t obj, blkptr_t *bp, uint64_t birth_txg,
+ uint64_t bytes, uint64_t comp, uint64_t uncomp, dmu_tx_t *tx)
+{
+ dmu_buf_t *db;
+ bptree_phys_t *bt;
+ bptree_entry_phys_t *bte;
+
+ /*
+ * bptree objects are in the pool mos, therefore they can only be
+ * modified in syncing context. Furthermore, this is only modified
+ * by the sync thread, so no locking is necessary.
+ */
+ ASSERT(dmu_tx_is_syncing(tx));
+
+ VERIFY3U(0, ==, dmu_bonus_hold(os, obj, FTAG, &db));
+ bt = db->db_data;
+
+ bte = kmem_zalloc(sizeof (*bte), KM_SLEEP);
+ bte->be_birth_txg = birth_txg;
+ bte->be_bp = *bp;
+ dmu_write(os, obj, bt->bt_end * sizeof (*bte), sizeof (*bte), bte, tx);
+ kmem_free(bte, sizeof (*bte));
+
+ dmu_buf_will_dirty(db, tx);
+ bt->bt_end++;
+ bt->bt_bytes += bytes;
+ bt->bt_comp += comp;
+ bt->bt_uncomp += uncomp;
+ dmu_buf_rele(db, FTAG);
+}
+
+/* ARGSUSED */
+static int
+bptree_visit_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
+ const zbookmark_phys_t *zb, const dnode_phys_t *dnp, void *arg)
+{
+ int err;
+ struct bptree_args *ba = arg;
+
+ if (zb->zb_level == ZB_DNODE_LEVEL || BP_IS_HOLE(bp) ||
+ BP_IS_REDACTED(bp))
+ return (0);
+
+ err = ba->ba_func(ba->ba_arg, bp, ba->ba_tx);
+ if (err == 0 && ba->ba_free) {
+ ba->ba_phys->bt_bytes -= bp_get_dsize_sync(spa, bp);
+ ba->ba_phys->bt_comp -= BP_GET_PSIZE(bp);
+ ba->ba_phys->bt_uncomp -= BP_GET_UCSIZE(bp);
+ }
+ return (err);
+}
+
+/*
+ * If "free" is set:
+ * - It is assumed that "func" will be freeing the block pointers.
+ * - If "func" returns nonzero, the bookmark will be remembered and
+ * iteration will be restarted from this point on next invocation.
+ * - If an i/o error is encountered (e.g. "func" returns EIO or ECKSUM),
+ * bptree_iterate will remember the bookmark, continue traversing
+ * any additional entries, and return 0.
+ *
+ * If "free" is not set, traversal will stop and return an error if
+ * an i/o error is encountered.
+ *
+ * In either case, if zfs_free_leak_on_eio is set, i/o errors will be
+ * ignored and traversal will continue (i.e. TRAVERSE_HARD will be passed to
+ * traverse_dataset_destroyed()).
+ */
+int
+bptree_iterate(objset_t *os, uint64_t obj, boolean_t free, bptree_itor_t func,
+ void *arg, dmu_tx_t *tx)
+{
+ boolean_t ioerr = B_FALSE;
+ int err;
+ uint64_t i;
+ dmu_buf_t *db;
+ struct bptree_args ba;
+
+ ASSERT(!free || dmu_tx_is_syncing(tx));
+
+ err = dmu_bonus_hold(os, obj, FTAG, &db);
+ if (err != 0)
+ return (err);
+
+ if (free)
+ dmu_buf_will_dirty(db, tx);
+
+ ba.ba_phys = db->db_data;
+ ba.ba_free = free;
+ ba.ba_func = func;
+ ba.ba_arg = arg;
+ ba.ba_tx = tx;
+
+ err = 0;
+ for (i = ba.ba_phys->bt_begin; i < ba.ba_phys->bt_end; i++) {
+ bptree_entry_phys_t bte;
+ int flags = TRAVERSE_PREFETCH_METADATA | TRAVERSE_POST |
+ TRAVERSE_NO_DECRYPT;
+
+ err = dmu_read(os, obj, i * sizeof (bte), sizeof (bte),
+ &bte, DMU_READ_NO_PREFETCH);
+ if (err != 0)
+ break;
+
+ if (zfs_free_leak_on_eio)
+ flags |= TRAVERSE_HARD;
+ zfs_dbgmsg("bptree index %lld: traversing from min_txg=%lld "
+ "bookmark %lld/%lld/%lld/%lld",
+ (longlong_t)i,
+ (longlong_t)bte.be_birth_txg,
+ (longlong_t)bte.be_zb.zb_objset,
+ (longlong_t)bte.be_zb.zb_object,
+ (longlong_t)bte.be_zb.zb_level,
+ (longlong_t)bte.be_zb.zb_blkid);
+ err = traverse_dataset_destroyed(os->os_spa, &bte.be_bp,
+ bte.be_birth_txg, &bte.be_zb, flags,
+ bptree_visit_cb, &ba);
+ if (free) {
+ /*
+ * The callback has freed the visited block pointers.
+ * Record our traversal progress on disk, either by
+ * updating this record's bookmark, or by logically
+ * removing this record by advancing bt_begin.
+ */
+ if (err != 0) {
+ /* save bookmark for future resume */
+ ASSERT3U(bte.be_zb.zb_objset, ==,
+ ZB_DESTROYED_OBJSET);
+ ASSERT0(bte.be_zb.zb_level);
+ dmu_write(os, obj, i * sizeof (bte),
+ sizeof (bte), &bte, tx);
+ if (err == EIO || err == ECKSUM ||
+ err == ENXIO) {
+ /*
+ * Skip the rest of this tree and
+ * continue on to the next entry.
+ */
+ err = 0;
+ ioerr = B_TRUE;
+ } else {
+ break;
+ }
+ } else if (ioerr) {
+ /*
+ * This entry is finished, but there were
+ * i/o errors on previous entries, so we
+ * can't adjust bt_begin. Set this entry's
+ * be_birth_txg such that it will be
+ * treated as a no-op in future traversals.
+ */
+ bte.be_birth_txg = UINT64_MAX;
+ dmu_write(os, obj, i * sizeof (bte),
+ sizeof (bte), &bte, tx);
+ }
+
+ if (!ioerr) {
+ ba.ba_phys->bt_begin++;
+ (void) dmu_free_range(os, obj,
+ i * sizeof (bte), sizeof (bte), tx);
+ }
+ } else if (err != 0) {
+ break;
+ }
+ }
+
+ ASSERT(!free || err != 0 || ioerr ||
+ ba.ba_phys->bt_begin == ba.ba_phys->bt_end);
+
+ /* if all blocks are free there should be no used space */
+ if (ba.ba_phys->bt_begin == ba.ba_phys->bt_end) {
+ if (zfs_free_leak_on_eio) {
+ ba.ba_phys->bt_bytes = 0;
+ ba.ba_phys->bt_comp = 0;
+ ba.ba_phys->bt_uncomp = 0;
+ }
+
+ ASSERT0(ba.ba_phys->bt_bytes);
+ ASSERT0(ba.ba_phys->bt_comp);
+ ASSERT0(ba.ba_phys->bt_uncomp);
+ }
+
+ dmu_buf_rele(db, FTAG);
+
+ return (err);
+}
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