module/zfs/bptree.c

   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 http://www.opensolaris.org/os/licensing.
  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, 2014 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/refcount.h>
  37 #include <sys/spa.h>
  38
  39 /*
  40  * A bptree is a queue of root block pointers from destroyed datasets. When a
  41  * dataset is destroyed its root block pointer is put on the end of the pool's
  42  * bptree queue so the dataset's blocks can be freed asynchronously by
  43  * dsl_scan_sync. This allows the delete operation to finish without traversing
  44  * all the dataset's blocks.
  45  *
  46  * Note that while bt_begin and bt_end are only ever incremented in this code,
  47  * they are effectively reset to 0 every time the entire bptree is freed because
  48  * the bptree's object is destroyed and re-created.
  49  */
  50
  51 struct bptree_args {
  52         bptree_phys_t *ba_phys; /* data in bonus buffer, dirtied if freeing */
  53         boolean_t ba_free;      /* true if freeing during traversal */
  54
  55         bptree_itor_t *ba_func; /* function to call for each blockpointer */
  56         void *ba_arg;           /* caller supplied argument to ba_func */
  57         dmu_tx_t *ba_tx;        /* caller supplied tx, NULL if not freeing */
  58 } bptree_args_t;
  59
  60 uint64_t
  61 bptree_alloc(objset_t *os, dmu_tx_t *tx)
  62 {
  63         uint64_t obj;
  64         dmu_buf_t *db;
  65         bptree_phys_t *bt;
  66
  67         obj = dmu_object_alloc(os, DMU_OTN_UINT64_METADATA,
  68             SPA_MAXBLOCKSIZE, DMU_OTN_UINT64_METADATA,
  69             sizeof (bptree_phys_t), tx);
  70
  71         /*
  72          * Bonus buffer contents are already initialized to 0, but for
  73          * readability we make it explicit.
  74          */
  75         VERIFY3U(0, ==, dmu_bonus_hold(os, obj, FTAG, &db));
  76         dmu_buf_will_dirty(db, tx);
  77         bt = db->db_data;
  78         bt->bt_begin = 0;
  79         bt->bt_end = 0;
  80         bt->bt_bytes = 0;
  81         bt->bt_comp = 0;
  82         bt->bt_uncomp = 0;
  83         dmu_buf_rele(db, FTAG);
  84
  85         return (obj);
  86 }
  87
  88 int
  89 bptree_free(objset_t *os, uint64_t obj, dmu_tx_t *tx)
  90 {
  91         dmu_buf_t *db;
  92         bptree_phys_t *bt;
  93
  94         VERIFY3U(0, ==, dmu_bonus_hold(os, obj, FTAG, &db));
  95         bt = db->db_data;
  96         ASSERT3U(bt->bt_begin, ==, bt->bt_end);
  97         ASSERT0(bt->bt_bytes);
  98         ASSERT0(bt->bt_comp);
  99         ASSERT0(bt->bt_uncomp);
 100         dmu_buf_rele(db, FTAG);
 101
 102         return (dmu_object_free(os, obj, tx));
 103 }
 104
 105 boolean_t
 106 bptree_is_empty(objset_t *os, uint64_t obj)
 107 {
 108         dmu_buf_t *db;
 109         bptree_phys_t *bt;
 110         boolean_t rv;
 111
 112         VERIFY0(dmu_bonus_hold(os, obj, FTAG, &db));
 113         bt = db->db_data;
 114         rv = (bt->bt_begin == bt->bt_end);
 115         dmu_buf_rele(db, FTAG);
 116         return (rv);
 117 }
 118
 119 void
 120 bptree_add(objset_t *os, uint64_t obj, blkptr_t *bp, uint64_t birth_txg,
 121     uint64_t bytes, uint64_t comp, uint64_t uncomp, dmu_tx_t *tx)
 122 {
 123         dmu_buf_t *db;
 124         bptree_phys_t *bt;
 125         bptree_entry_phys_t *bte;
 126
 127         /*
 128          * bptree objects are in the pool mos, therefore they can only be
 129          * modified in syncing context. Furthermore, this is only modified
 130          * by the sync thread, so no locking is necessary.
 131          */
 132         ASSERT(dmu_tx_is_syncing(tx));
 133
 134         VERIFY3U(0, ==, dmu_bonus_hold(os, obj, FTAG, &db));
 135         bt = db->db_data;
 136
 137         bte = kmem_zalloc(sizeof (*bte), KM_SLEEP);
 138         bte->be_birth_txg = birth_txg;
 139         bte->be_bp = *bp;
 140         dmu_write(os, obj, bt->bt_end * sizeof (*bte), sizeof (*bte), bte, tx);
 141         kmem_free(bte, sizeof (*bte));
 142
 143         dmu_buf_will_dirty(db, tx);
 144         bt->bt_end++;
 145         bt->bt_bytes += bytes;
 146         bt->bt_comp += comp;
 147         bt->bt_uncomp += uncomp;
 148         dmu_buf_rele(db, FTAG);
 149 }
 150
 151 /* ARGSUSED */
 152 static int
 153 bptree_visit_cb(spa_t *spa, zilog_t *zilog, const blkptr_t *bp,
 154     const zbookmark_phys_t *zb, const dnode_phys_t *dnp, void *arg)
 155 {
 156         int err;
 157         struct bptree_args *ba = arg;
 158
 159         if (BP_IS_HOLE(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
 217                 err = dmu_read(os, obj, i * sizeof (bte), sizeof (bte),
 218                     &bte, DMU_READ_NO_PREFETCH);
 219                 if (err != 0)
 220                         break;
 221
 222                 if (zfs_free_leak_on_eio)
 223                         flags |= TRAVERSE_HARD;
 224                 zfs_dbgmsg("bptree index %lld: traversing from min_txg=%lld "
 225                     "bookmark %lld/%lld/%lld/%lld",
 226                     i, (longlong_t)bte.be_birth_txg,
 227                     (longlong_t)bte.be_zb.zb_objset,
 228                     (longlong_t)bte.be_zb.zb_object,
 229                     (longlong_t)bte.be_zb.zb_level,
 230                     (longlong_t)bte.be_zb.zb_blkid);
 231                 err = traverse_dataset_destroyed(os->os_spa, &bte.be_bp,
 232                     bte.be_birth_txg, &bte.be_zb, flags,
 233                     bptree_visit_cb, &ba);
 234                 if (free) {
 235                         /*
 236                          * The callback has freed the visited block pointers.
 237                          * Record our traversal progress on disk, either by
 238                          * updating this record's bookmark, or by logically
 239                          * removing this record by advancing bt_begin.
 240                          */
 241                         if (err != 0) {
 242                                 /* save bookmark for future resume */
 243                                 ASSERT3U(bte.be_zb.zb_objset, ==,
 244                                     ZB_DESTROYED_OBJSET);
 245                                 ASSERT0(bte.be_zb.zb_level);
 246                                 dmu_write(os, obj, i * sizeof (bte),
 247                                     sizeof (bte), &bte, tx);
 248                                 if (err == EIO || err == ECKSUM ||
 249                                     err == ENXIO) {
 250                                         /*
 251                                          * Skip the rest of this tree and
 252                                          * continue on to the next entry.
 253                                          */
 254                                         err = 0;
 255                                         ioerr = B_TRUE;
 256                                 } else {
 257                                         break;
 258                                 }
 259                         } else if (ioerr) {
 260                                 /*
 261                                  * This entry is finished, but there were
 262                                  * i/o errors on previous entries, so we
 263                                  * can't adjust bt_begin.  Set this entry's
 264                                  * be_birth_txg such that it will be
 265                                  * treated as a no-op in future traversals.
 266                                  */
 267                                 bte.be_birth_txg = UINT64_MAX;
 268                                 dmu_write(os, obj, i * sizeof (bte),
 269                                     sizeof (bte), &bte, tx);
 270                         }
 271
 272                         if (!ioerr) {
 273                                 ba.ba_phys->bt_begin++;
 274                                 (void) dmu_free_range(os, obj,
 275                                     i * sizeof (bte), sizeof (bte), tx);
 276                         }
 277                 } else if (err != 0) {
 278                         break;
 279                 }
 280         }
 281
 282         ASSERT(!free || err != 0 || ioerr ||
 283             ba.ba_phys->bt_begin == ba.ba_phys->bt_end);
 284
 285         /* if all blocks are free there should be no used space */
 286         if (ba.ba_phys->bt_begin == ba.ba_phys->bt_end) {
 287                 if (zfs_free_leak_on_eio) {
 288                         ba.ba_phys->bt_bytes = 0;
 289                         ba.ba_phys->bt_comp = 0;
 290                         ba.ba_phys->bt_uncomp = 0;
 291                 }
 292
 293                 ASSERT0(ba.ba_phys->bt_bytes);
 294                 ASSERT0(ba.ba_phys->bt_comp);
 295                 ASSERT0(ba.ba_phys->bt_uncomp);
 296         }
 297
 298         dmu_buf_rele(db, FTAG);
 299
 300         return (err);
 301 }