bptree.c

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    1 /*
    2  * CDDL HEADER START
    3  *
    4  * The contents of this file are subject to the terms of the
    5  * Common Development and Distribution License (the "License").
    6  * You may not use this file except in compliance with the License.
    7  *
    8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
    9  * or https://opensource.org/licenses/CDDL-1.0.
   10  * See the License for the specific language governing permissions
   11  * and limitations under the License.
   12  *
   13  * When distributing Covered Code, include this CDDL HEADER in each
   14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
   15  * If applicable, add the following below this CDDL HEADER, with the
   16  * fields enclosed by brackets "[]" replaced with your own identifying
   17  * information: Portions Copyright [yyyy] [name of copyright owner]
   18  *
   19  * CDDL HEADER END
   20  */
   21 
   22 /*
   23  * Copyright (c) 2011, 2018 by Delphix. All rights reserved.
   24  */
   25 
   26 #include <sys/arc.h>
   27 #include <sys/bptree.h>
   28 #include <sys/dmu.h>
   29 #include <sys/dmu_objset.h>
   30 #include <sys/dmu_tx.h>
   31 #include <sys/dmu_traverse.h>
   32 #include <sys/dsl_dataset.h>
   33 #include <sys/dsl_dir.h>
   34 #include <sys/dsl_pool.h>
   35 #include <sys/dnode.h>
   36 #include <sys/spa.h>
   37 
   38 /*
   39  * A bptree is a queue of root block pointers from destroyed datasets. When a
   40  * dataset is destroyed its root block pointer is put on the end of the pool's
   41  * bptree queue so the dataset's blocks can be freed asynchronously by
   42  * dsl_scan_sync. This allows the delete operation to finish without traversing
   43  * all the dataset's blocks.
   44  *
   45  * Note that while bt_begin and bt_end are only ever incremented in this code,
   46  * they are effectively reset to 0 every time the entire bptree is freed because
   47  * the bptree's object is destroyed and re-created.
   48  */
   49 
   50 struct bptree_args {
   51         bptree_phys_t *ba_phys; /* data in bonus buffer, dirtied if freeing */
   52         boolean_t ba_free;      /* true if freeing during traversal */
   53 
   54         bptree_itor_t *ba_func; /* function to call for each blockpointer */
   55         void *ba_arg;           /* caller supplied argument to ba_func */
   56         dmu_tx_t *ba_tx;        /* caller supplied tx, NULL if not freeing */
   57 } bptree_args_t;
   58 
   59 uint64_t
   60 bptree_alloc(objset_t *os, dmu_tx_t *tx)
   61 {
   62         uint64_t obj;
   63         dmu_buf_t *db;
   64         bptree_phys_t *bt;
   65 
   66         obj = dmu_object_alloc(os, DMU_OTN_UINT64_METADATA,
   67             SPA_OLD_MAXBLOCKSIZE, DMU_OTN_UINT64_METADATA,
   68             sizeof (bptree_phys_t), tx);
   69 
   70         /*
   71          * Bonus buffer contents are already initialized to 0, but for
   72          * readability we make it explicit.
   73          */
   74         VERIFY3U(0, ==, dmu_bonus_hold(os, obj, FTAG, &db));
   75         dmu_buf_will_dirty(db, tx);
   76         bt = db->db_data;
   77         bt->bt_begin = 0;
   78         bt->bt_end = 0;
   79         bt->bt_bytes = 0;
   80         bt->bt_comp = 0;
   81         bt->bt_uncomp = 0;
   82         dmu_buf_rele(db, FTAG);
   83 
   84         return (obj);
   85 }
   86 
   87 int
   88 bptree_free(objset_t *os, uint64_t obj, dmu_tx_t *tx)
   89 {
   90         dmu_buf_t *db;
   91         bptree_phys_t *bt;
   92 
   93         VERIFY3U(0, ==, dmu_bonus_hold(os, obj, FTAG, &db));
   94         bt = db->db_data;
   95         ASSERT3U(bt->bt_begin, ==, bt->bt_end);
   96         ASSERT0(bt->bt_bytes);
   97         ASSERT0(bt->bt_comp);
   98         ASSERT0(bt->bt_uncomp);
   99         dmu_buf_rele(db, FTAG);
  100 
  101         return (dmu_object_free(os, obj, tx));
  102 }
  103 
  104 boolean_t
  105 bptree_is_empty(objset_t *os, uint64_t obj)
  106 {
  107         dmu_buf_t *db;
  108         bptree_phys_t *bt;
  109         boolean_t rv;
  110 
  111         VERIFY0(dmu_bonus_hold(os, obj, FTAG, &db));
  112         bt = db->db_data;
  113         rv = (bt->bt_begin == bt->bt_end);
  114         dmu_buf_rele(db, FTAG);
  115         return (rv);
  116 }
  117 
  118 void
  119 bptree_add(objset_t *os, uint64_t obj, blkptr_t *bp, uint64_t birth_txg,
  120     uint64_t bytes, uint64_t comp, uint64_t uncomp, dmu_tx_t *tx)
  121 {
  122         dmu_buf_t *db;
  123         bptree_phys_t *bt;
  124         bptree_entry_phys_t *bte;
  125 
  126         /*
  127          * bptree objects are in the pool mos, therefore they can only be
  128          * modified in syncing context. Furthermore, this is only modified
  129          * by the sync thread, so no locking is necessary.
  130          */
  131         ASSERT(dmu_tx_is_syncing(tx));
  132 
  133         VERIFY3U(0, ==, dmu_bonus_hold(os, obj, FTAG, &db));
  134         bt = db->db_data;
  135 
  136         bte = kmem_zalloc(sizeof (*bte), KM_SLEEP);
  137         bte->be_birth_txg = birth_txg;
  138         bte->be_bp = *bp;
  139         dmu_write(os, obj, bt->bt_end * sizeof (*bte), sizeof (*bte), bte, tx);
  140         kmem_free(bte, sizeof (*bte));
  141 
  142         dmu_buf_will_dirty(db, tx);
  143         bt->bt_end++;
  144         bt->bt_bytes += bytes;
  145         bt->bt_comp += comp;
  146         bt->bt_uncomp += uncomp;
  147         dmu_buf_rele(db, FTAG);
  148 }
  149 
  150 static int
  151 bptree_visit_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
  152     const zbookmark_phys_t *zb, const dnode_phys_t *dnp, void *arg)
  153 {
  154         (void) zilog, (void) dnp;
  155         int err;
  156         struct bptree_args *ba = arg;
  157 
  158         if (zb->zb_level == ZB_DNODE_LEVEL || BP_IS_HOLE(bp) ||
  159             BP_IS_REDACTED(bp))
  160                 return (0);
  161 
  162         err = ba->ba_func(ba->ba_arg, bp, ba->ba_tx);
  163         if (err == 0 && ba->ba_free) {
  164                 ba->ba_phys->bt_bytes -= bp_get_dsize_sync(spa, bp);
  165                 ba->ba_phys->bt_comp -= BP_GET_PSIZE(bp);
  166                 ba->ba_phys->bt_uncomp -= BP_GET_UCSIZE(bp);
  167         }
  168         return (err);
  169 }
  170 
  171 /*
  172  * If "free" is set:
  173  *  - It is assumed that "func" will be freeing the block pointers.
  174  *  - If "func" returns nonzero, the bookmark will be remembered and
  175  *    iteration will be restarted from this point on next invocation.
  176  *  - If an i/o error is encountered (e.g. "func" returns EIO or ECKSUM),
  177  *    bptree_iterate will remember the bookmark, continue traversing
  178  *    any additional entries, and return 0.
  179  *
  180  * If "free" is not set, traversal will stop and return an error if
  181  * an i/o error is encountered.
  182  *
  183  * In either case, if zfs_free_leak_on_eio is set, i/o errors will be
  184  * ignored and traversal will continue (i.e. TRAVERSE_HARD will be passed to
  185  * traverse_dataset_destroyed()).
  186  */
  187 int
  188 bptree_iterate(objset_t *os, uint64_t obj, boolean_t free, bptree_itor_t func,
  189     void *arg, dmu_tx_t *tx)
  190 {
  191         boolean_t ioerr = B_FALSE;
  192         int err;
  193         uint64_t i;
  194         dmu_buf_t *db;
  195         struct bptree_args ba;
  196 
  197         ASSERT(!free || dmu_tx_is_syncing(tx));
  198 
  199         err = dmu_bonus_hold(os, obj, FTAG, &db);
  200         if (err != 0)
  201                 return (err);
  202 
  203         if (free)
  204                 dmu_buf_will_dirty(db, tx);
  205 
  206         ba.ba_phys = db->db_data;
  207         ba.ba_free = free;
  208         ba.ba_func = func;
  209         ba.ba_arg = arg;
  210         ba.ba_tx = tx;
  211 
  212         err = 0;
  213         for (i = ba.ba_phys->bt_begin; i < ba.ba_phys->bt_end; i++) {
  214                 bptree_entry_phys_t bte;
  215                 int flags = TRAVERSE_PREFETCH_METADATA | TRAVERSE_POST |
  216                     TRAVERSE_NO_DECRYPT;
  217 
  218                 err = dmu_read(os, obj, i * sizeof (bte), sizeof (bte),
  219                     &bte, DMU_READ_NO_PREFETCH);
  220                 if (err != 0)
  221                         break;
  222 
  223                 if (zfs_free_leak_on_eio)
  224                         flags |= TRAVERSE_HARD;
  225                 zfs_dbgmsg("bptree index %lld: traversing from min_txg=%lld "
  226                     "bookmark %lld/%lld/%lld/%lld",
  227                     (longlong_t)i,
  228                     (longlong_t)bte.be_birth_txg,
  229                     (longlong_t)bte.be_zb.zb_objset,
  230                     (longlong_t)bte.be_zb.zb_object,
  231                     (longlong_t)bte.be_zb.zb_level,
  232                     (longlong_t)bte.be_zb.zb_blkid);
  233                 err = traverse_dataset_destroyed(os->os_spa, &bte.be_bp,
  234                     bte.be_birth_txg, &bte.be_zb, flags,
  235                     bptree_visit_cb, &ba);
  236                 if (free) {
  237                         /*
  238                          * The callback has freed the visited block pointers.
  239                          * Record our traversal progress on disk, either by
  240                          * updating this record's bookmark, or by logically
  241                          * removing this record by advancing bt_begin.
  242                          */
  243                         if (err != 0) {
  244                                 /* save bookmark for future resume */
  245                                 ASSERT3U(bte.be_zb.zb_objset, ==,
  246                                     ZB_DESTROYED_OBJSET);
  247                                 ASSERT0(bte.be_zb.zb_level);
  248                                 dmu_write(os, obj, i * sizeof (bte),
  249                                     sizeof (bte), &bte, tx);
  250                                 if (err == EIO || err == ECKSUM ||
  251                                     err == ENXIO) {
  252                                         /*
  253                                          * Skip the rest of this tree and
  254                                          * continue on to the next entry.
  255                                          */
  256                                         err = 0;
  257                                         ioerr = B_TRUE;
  258                                 } else {
  259                                         break;
  260                                 }
  261                         } else if (ioerr) {
  262                                 /*
  263                                  * This entry is finished, but there were
  264                                  * i/o errors on previous entries, so we
  265                                  * can't adjust bt_begin.  Set this entry's
  266                                  * be_birth_txg such that it will be
  267                                  * treated as a no-op in future traversals.
  268                                  */
  269                                 bte.be_birth_txg = UINT64_MAX;
  270                                 dmu_write(os, obj, i * sizeof (bte),
  271                                     sizeof (bte), &bte, tx);
  272                         }
  273 
  274                         if (!ioerr) {
  275                                 ba.ba_phys->bt_begin++;
  276                                 (void) dmu_free_range(os, obj,
  277                                     i * sizeof (bte), sizeof (bte), tx);
  278                         }
  279                 } else if (err != 0) {
  280                         break;
  281                 }
  282         }
  283 
  284         ASSERT(!free || err != 0 || ioerr ||
  285             ba.ba_phys->bt_begin == ba.ba_phys->bt_end);
  286 
  287         /* if all blocks are free there should be no used space */
  288         if (ba.ba_phys->bt_begin == ba.ba_phys->bt_end) {
  289                 if (zfs_free_leak_on_eio) {
  290                         ba.ba_phys->bt_bytes = 0;
  291                         ba.ba_phys->bt_comp = 0;
  292                         ba.ba_phys->bt_uncomp = 0;
  293                 }
  294 
  295                 ASSERT0(ba.ba_phys->bt_bytes);
  296                 ASSERT0(ba.ba_phys->bt_comp);
  297                 ASSERT0(ba.ba_phys->bt_uncomp);
  298         }
  299 
  300         dmu_buf_rele(db, FTAG);
  301 
  302         return (err);
  303 }
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FreeBSD/Linux Kernel Cross Reference sys/contrib/openzfs/module/zfs/bptree.c

FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/module/zfs/bptree.c
