sys/vfs/hammer/hammer_undo.c

   1 /*
   2  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 /*
  36  * HAMMER undo - undo buffer/FIFO management.
  37  */
  38
  39 #include "hammer.h"
  40
  41 static int
  42 hammer_und_rb_compare(hammer_undo_t node1, hammer_undo_t node2)
  43 {
  44         if (node1->offset < node2->offset)
  45                 return(-1);
  46         if (node1->offset > node2->offset)
  47                 return(1);
  48         return(0);
  49 }
  50
  51 RB_GENERATE2(hammer_und_rb_tree, hammer_undo, rb_node,
  52              hammer_und_rb_compare, hammer_off_t, offset);
  53
  54 /*
  55  * Convert a zone-3 undo offset into a zone-2 buffer offset.
  56  */
  57 hammer_off_t
  58 hammer_undo_lookup(hammer_mount_t hmp, hammer_off_t zone3_off, int *errorp)
  59 {
  60         hammer_volume_t root_volume;
  61         hammer_blockmap_t undomap __debugvar;
  62         hammer_off_t result_offset;
  63
  64         KKASSERT(hammer_is_zone_undo(zone3_off));
  65         root_volume = hammer_get_root_volume(hmp, errorp);
  66         if (*errorp)
  67                 return(0);
  68         undomap = &hmp->blockmap[HAMMER_ZONE_UNDO_INDEX];
  69         KKASSERT(HAMMER_ZONE_DECODE(undomap->alloc_offset) == HAMMER_ZONE_UNDO_INDEX);
  70         KKASSERT(zone3_off < undomap->alloc_offset);
  71
  72         result_offset = hammer_xlate_to_undo(root_volume->ondisk, zone3_off);
  73
  74         hammer_rel_volume(root_volume, 0);
  75         return(result_offset);
  76 }
  77
  78 /*
  79  * Generate UNDO record(s) for the block of data at the specified zone1
  80  * or zone2 offset.
  81  *
  82  * The recovery code will execute UNDOs in reverse order, allowing overlaps.
  83  * All the UNDOs are executed together so if we already laid one down we
  84  * do not have to lay another one down for the same range.
  85  *
  86  * For HAMMER version 4+ UNDO a 512 byte boundary is enforced and a PAD
  87  * will be laid down for any unused space.  UNDO FIFO media structures
  88  * will implement the hdr_seq field (it used to be reserved01), and
  89  * both flush and recovery mechanics will be very different.
  90  *
  91  * WARNING!  See also hammer_generate_redo() in hammer_redo.c
  92  */
  93 int
  94 hammer_generate_undo(hammer_transaction_t trans,
  95                      hammer_off_t zone_off, void *base, int len)
  96 {
  97         hammer_mount_t hmp;
  98         hammer_volume_t root_volume;
  99         hammer_blockmap_t undomap;
 100         hammer_buffer_t buffer = NULL;
 101         hammer_fifo_undo_t undo;
 102         hammer_fifo_tail_t tail;
 103         hammer_off_t next_offset;
 104         int error;
 105         int bytes;
 106         int n;
 107
 108         hmp = trans->hmp;
 109
 110         /*
 111          * A SYNC record may be required before we can lay down a general
 112          * UNDO.  This ensures that the nominal recovery span contains
 113          * at least one SYNC record telling the recovery code how far
 114          * out-of-span it must go to run the REDOs.
 115          */
 116         if ((hmp->flags & HAMMER_MOUNT_REDO_SYNC) == 0 &&
 117             hmp->version >= HAMMER_VOL_VERSION_FOUR) {
 118                 hammer_generate_redo_sync(trans);
 119         }
 120
 121         /*
 122          * Enter the offset into our undo history.  If there is an existing
 123          * undo we do not have to generate a new one.
 124          */
 125         if (hammer_enter_undo_history(hmp, zone_off, len) == EALREADY)
 126                 return(0);
 127
 128         root_volume = trans->rootvol;
 129         undomap = &hmp->blockmap[HAMMER_ZONE_UNDO_INDEX];
 130
 131         /* no undo recursion */
 132         hammer_modify_volume_noundo(NULL, root_volume);
 133         hammer_lock_ex(&hmp->undo_lock);
 134
 135         /* undo had better not roll over (loose test) */
 136         if (hammer_undo_space(trans) < len + HAMMER_BUFSIZE*3)
 137                 hpanic("insufficient UNDO/REDO FIFO space for undo!");
 138
 139         /*
 140          * Loop until the undo for the entire range has been laid down.
 141          */
 142         while (len) {
 143                 /*
 144                  * Fetch the layout offset in the UNDO FIFO, wrap it as
 145                  * necessary.
 146                  */
 147                 if (undomap->next_offset == undomap->alloc_offset)
 148                         undomap->next_offset = HAMMER_ENCODE_UNDO(0);
 149                 next_offset = undomap->next_offset;
 150
 151                 /*
 152                  * This is a tail-chasing FIFO, when we hit the start of a new
 153                  * buffer we don't have to read it in.
 154                  */
 155                 if ((next_offset & HAMMER_BUFMASK) == 0) {
 156                         undo = hammer_bnew(hmp, next_offset, &error, &buffer);
 157                         hammer_format_undo(undo, hmp->undo_seqno ^ 0x40000000);
 158                 } else {
 159                         undo = hammer_bread(hmp, next_offset, &error, &buffer);
 160                 }
 161                 if (error)
 162                         break;
 163                 /* no undo recursion */
 164                 hammer_modify_buffer_noundo(NULL, buffer);
 165
 166                 /*
 167                  * Calculate how big a media structure fits up to the next
 168                  * alignment point and how large a data payload we can
 169                  * accomodate.
 170                  *
 171                  * If n calculates to 0 or negative there is no room for
 172                  * anything but a PAD.
 173                  */
 174                 bytes = HAMMER_UNDO_ALIGN -
 175                         ((int)next_offset & HAMMER_UNDO_MASK);
 176                 n = bytes -
 177                     (int)sizeof(struct hammer_fifo_undo) -
 178                     (int)sizeof(struct hammer_fifo_tail);
 179
 180                 /*
 181                  * If available space is insufficient for any payload
 182                  * we have to lay down a PAD.
 183                  *
 184                  * The minimum PAD is 8 bytes and the head and tail will
 185                  * overlap each other in that case.  PADs do not have
 186                  * sequence numbers or CRCs.
 187                  *
 188                  * A PAD may not start on a boundary.  That is, every
 189                  * 512-byte block in the UNDO/REDO FIFO must begin with
 190                  * a record containing a sequence number.
 191                  */
 192                 if (n <= 0) {
 193                         KKASSERT(bytes >= sizeof(struct hammer_fifo_tail));
 194                         KKASSERT(((int)next_offset & HAMMER_UNDO_MASK) != 0);
 195                         tail = (void *)((char *)undo + bytes - sizeof(*tail));
 196                         if ((void *)undo != (void *)tail) {
 197                                 tail->tail_signature = HAMMER_TAIL_SIGNATURE;
 198                                 tail->tail_type = HAMMER_HEAD_TYPE_PAD;
 199                                 tail->tail_size = bytes;
 200                         }
 201                         undo->head.hdr_signature = HAMMER_HEAD_SIGNATURE;
 202                         undo->head.hdr_type = HAMMER_HEAD_TYPE_PAD;
 203                         undo->head.hdr_size = bytes;
 204                         /* NO CRC OR SEQ NO */
 205                         undomap->next_offset += bytes;
 206                         hammer_modify_buffer_done(buffer);
 207                         hammer_stats_undo += bytes;
 208                         continue;
 209                 }
 210
 211                 /*
 212                  * Calculate the actual payload and recalculate the size
 213                  * of the media structure as necessary.
 214                  */
 215                 if (n > len) {
 216                         n = len;
 217                         bytes = HAMMER_HEAD_DOALIGN(n) +
 218                                 (int)sizeof(struct hammer_fifo_undo) +
 219                                 (int)sizeof(struct hammer_fifo_tail);
 220                 }
 221                 if (hammer_debug_general & 0x0080) {
 222                         hdkprintf("undo %016jx %d %d\n",
 223                                 (intmax_t)next_offset, bytes, n);
 224                 }
 225
 226                 undo->head.hdr_signature = HAMMER_HEAD_SIGNATURE;
 227                 undo->head.hdr_type = HAMMER_HEAD_TYPE_UNDO;
 228                 undo->head.hdr_size = bytes;
 229                 undo->head.hdr_seq = hmp->undo_seqno++;
 230                 undo->head.hdr_crc = 0;
 231                 undo->undo_offset = zone_off;
 232                 undo->undo_data_bytes = n;
 233                 bcopy(base, undo + 1, n);
 234
 235                 tail = (void *)((char *)undo + bytes - sizeof(*tail));
 236                 tail->tail_signature = HAMMER_TAIL_SIGNATURE;
 237                 tail->tail_type = HAMMER_HEAD_TYPE_UNDO;
 238                 tail->tail_size = bytes;
 239
 240                 KKASSERT(bytes >= sizeof(undo->head));
 241                 hammer_crc_set_fifo_head(&undo->head, bytes);
 242                 undomap->next_offset += bytes;
 243                 hammer_stats_undo += bytes;
 244
 245                 /*
 246                  * Before we finish off the buffer we have to deal with any
 247                  * junk between the end of the media structure we just laid
 248                  * down and the UNDO alignment boundary.  We do this by laying
 249                  * down a dummy PAD.  Even though we will probably overwrite
 250                  * it almost immediately we have to do this so recovery runs
 251                  * can iterate the UNDO space without having to depend on
 252                  * the indices in the volume header.
 253                  *
 254                  * This dummy PAD will be overwritten on the next undo so
 255                  * we do not adjust undomap->next_offset.
 256                  */
 257                 bytes = HAMMER_UNDO_ALIGN -
 258                         ((int)undomap->next_offset & HAMMER_UNDO_MASK);
 259                 if (bytes != HAMMER_UNDO_ALIGN) {
 260                         KKASSERT(bytes >= sizeof(struct hammer_fifo_tail));
 261                         undo = (void *)(tail + 1);
 262                         tail = (void *)((char *)undo + bytes - sizeof(*tail));
 263                         if ((void *)undo != (void *)tail) {
 264                                 tail->tail_signature = HAMMER_TAIL_SIGNATURE;
 265                                 tail->tail_type = HAMMER_HEAD_TYPE_PAD;
 266                                 tail->tail_size = bytes;
 267                         }
 268                         undo->head.hdr_signature = HAMMER_HEAD_SIGNATURE;
 269                         undo->head.hdr_type = HAMMER_HEAD_TYPE_PAD;
 270                         undo->head.hdr_size = bytes;
 271                         /* NO CRC OR SEQ NO */
 272                 }
 273                 hammer_modify_buffer_done(buffer);
 274
 275                 /*
 276                  * Adjust for loop
 277                  */
 278                 len -= n;
 279                 base = (char *)base + n;
 280                 zone_off += n;
 281         }
 282         hammer_modify_volume_done(root_volume);
 283         hammer_unlock(&hmp->undo_lock);
 284
 285         if (buffer)
 286                 hammer_rel_buffer(buffer, 0);
 287         return(error);
 288 }
 289
 290 /*
 291  * Preformat a new UNDO block.  We could read the old one in but we get
 292  * better performance if we just pre-format a new one.
 293  *
 294  * The recovery code always works forwards so the caller just makes sure the
 295  * seqno is not contiguous with prior UNDOs or ancient UNDOs now being
 296  * overwritten.
 297  *
 298  * The preformatted UNDO headers use the smallest possible sector size
 299  * (512) to ensure that any missed media writes are caught.
 300  *
 301  * NOTE: Also used by the REDO code.
 302  */
 303 void
 304 hammer_format_undo(void *base, uint32_t seqno)
 305 {
 306         hammer_fifo_head_t head;
 307         hammer_fifo_tail_t tail;
 308         int i;
 309         int bytes = HAMMER_UNDO_ALIGN;
 310
 311         bzero(base, HAMMER_BUFSIZE);
 312
 313         for (i = 0; i < HAMMER_BUFSIZE; i += bytes) {
 314                 head = (void *)((char *)base + i);
 315                 tail = (void *)((char *)head + bytes - sizeof(*tail));
 316
 317                 head->hdr_signature = HAMMER_HEAD_SIGNATURE;
 318                 head->hdr_type = HAMMER_HEAD_TYPE_DUMMY;
 319                 head->hdr_size = bytes;
 320                 head->hdr_seq = seqno++;
 321                 head->hdr_crc = 0;
 322
 323                 tail->tail_signature = HAMMER_TAIL_SIGNATURE;
 324                 tail->tail_type = HAMMER_HEAD_TYPE_DUMMY;
 325                 tail->tail_size = bytes;
 326
 327                 hammer_crc_set_fifo_head(head, bytes);
 328         }
 329 }
 330
 331 /*
 332  * HAMMER version 4+ conversion support.
 333  *
 334  * Convert a HAMMER version < 4 UNDO FIFO area to a 4+ UNDO FIFO area.
 335  * The 4+ UNDO FIFO area is backwards compatible.  The conversion is
 336  * needed to initialize the sequence space and place headers on the
 337  * new 512-byte undo boundary.
 338  */
 339 int
 340 hammer_upgrade_undo_4(hammer_transaction_t trans)
 341 {
 342         hammer_mount_t hmp;
 343         hammer_volume_t root_volume;
 344         hammer_blockmap_t undomap;
 345         hammer_buffer_t buffer = NULL;
 346         hammer_fifo_head_t head;
 347         hammer_fifo_tail_t tail;
 348         hammer_off_t next_offset;
 349         uint32_t seqno;
 350         int error;
 351         int bytes;
 352
 353         hmp = trans->hmp;
 354
 355         root_volume = trans->rootvol;
 356
 357         /* no undo recursion */
 358         hammer_lock_ex(&hmp->undo_lock);
 359         hammer_modify_volume_noundo(NULL, root_volume);
 360
 361         /*
 362          * Adjust the in-core undomap and the on-disk undomap.
 363          */
 364         next_offset = HAMMER_ENCODE_UNDO(0);
 365         undomap = &hmp->blockmap[HAMMER_ZONE_UNDO_INDEX];
 366         undomap->next_offset = next_offset;
 367         undomap->first_offset = next_offset;
 368
 369         undomap = &root_volume->ondisk->vol0_blockmap[HAMMER_ZONE_UNDO_INDEX];
 370         undomap->next_offset = next_offset;
 371         undomap->first_offset = next_offset;
 372
 373         /*
 374          * Loop over the entire UNDO space creating DUMMY entries.  Sequence
 375          * numbers are assigned.
 376          */
 377         seqno = 0;
 378         bytes = HAMMER_UNDO_ALIGN;
 379
 380         while (next_offset != undomap->alloc_offset) {
 381                 head = hammer_bnew(hmp, next_offset, &error, &buffer);
 382                 if (error)
 383                         break;
 384                 hammer_modify_buffer_noundo(NULL, buffer);
 385                 tail = (void *)((char *)head + bytes - sizeof(*tail));
 386
 387                 head->hdr_signature = HAMMER_HEAD_SIGNATURE;
 388                 head->hdr_type = HAMMER_HEAD_TYPE_DUMMY;
 389                 head->hdr_size = bytes;
 390                 head->hdr_seq = seqno;
 391                 head->hdr_crc = 0;
 392
 393                 tail = (void *)((char *)head + bytes - sizeof(*tail));
 394                 tail->tail_signature = HAMMER_TAIL_SIGNATURE;
 395                 tail->tail_type = HAMMER_HEAD_TYPE_DUMMY;
 396                 tail->tail_size = bytes;
 397
 398                 hammer_crc_set_fifo_head(head, bytes);
 399                 hammer_modify_buffer_done(buffer);
 400
 401                 hammer_stats_undo += bytes;
 402                 next_offset += HAMMER_UNDO_ALIGN;
 403                 ++seqno;
 404         }
 405
 406         /*
 407          * The sequence number will be the next sequence number to lay down.
 408          */
 409         hmp->undo_seqno = seqno;
 410         hmkprintf(hmp, "version upgrade seqno start %08x\n", seqno);
 411
 412         hammer_modify_volume_done(root_volume);
 413         hammer_unlock(&hmp->undo_lock);
 414
 415         if (buffer)
 416                 hammer_rel_buffer(buffer, 0);
 417         return (error);
 418 }
 419
 420 /*
 421  * UNDO HISTORY API
 422  *
 423  * It is not necessary to layout an undo record for the same address space
 424  * multiple times.  Maintain a cache of recent undo's.
 425  */
 426
 427 /*
 428  * Enter an undo into the history.  Return EALREADY if the request completely
 429  * covers a previous request.
 430  */
 431 int
 432 hammer_enter_undo_history(hammer_mount_t hmp, hammer_off_t offset, int bytes)
 433 {
 434         hammer_undo_t node;
 435         hammer_undo_t onode __debugvar;
 436
 437         node = RB_LOOKUP(hammer_und_rb_tree, &hmp->rb_undo_root, offset);
 438         if (node) {
 439                 TAILQ_REMOVE(&hmp->undo_lru_list, node, lru_entry);
 440                 TAILQ_INSERT_TAIL(&hmp->undo_lru_list, node, lru_entry);
 441                 if (bytes <= node->bytes)
 442                         return(EALREADY);
 443                 node->bytes = bytes;
 444                 return(0);
 445         }
 446         if (hmp->undo_alloc != HAMMER_MAX_UNDOS) {
 447                 node = &hmp->undos[hmp->undo_alloc++];
 448         } else {
 449                 node = TAILQ_FIRST(&hmp->undo_lru_list);
 450                 TAILQ_REMOVE(&hmp->undo_lru_list, node, lru_entry);
 451                 RB_REMOVE(hammer_und_rb_tree, &hmp->rb_undo_root, node);
 452         }
 453         node->offset = offset;
 454         node->bytes = bytes;
 455         TAILQ_INSERT_TAIL(&hmp->undo_lru_list, node, lru_entry);
 456         onode = RB_INSERT(hammer_und_rb_tree, &hmp->rb_undo_root, node);
 457         KKASSERT(onode == NULL);
 458         return(0);
 459 }
 460
 461 void
 462 hammer_clear_undo_history(hammer_mount_t hmp)
 463 {
 464         RB_INIT(&hmp->rb_undo_root);
 465         TAILQ_INIT(&hmp->undo_lru_list);
 466         hmp->undo_alloc = 0;
 467 }
 468
 469 /*
 470  * Return how much of the undo FIFO has been used
 471  *
 472  * The calculation includes undo FIFO space still reserved from a previous
 473  * flush (because it will still be run on recovery if a crash occurs and
 474  * we can't overwrite it yet).
 475  */
 476 int64_t
 477 hammer_undo_used(hammer_transaction_t trans)
 478 {
 479         hammer_blockmap_t cundomap;
 480         hammer_blockmap_t dundomap;
 481         int64_t max_bytes __debugvar;
 482         int64_t bytes;
 483
 484         cundomap = &trans->hmp->blockmap[HAMMER_ZONE_UNDO_INDEX];
 485         dundomap = &trans->rootvol->ondisk->
 486                                 vol0_blockmap[HAMMER_ZONE_UNDO_INDEX];
 487
 488         if (dundomap->first_offset <= cundomap->next_offset) {
 489                 bytes = cundomap->next_offset - dundomap->first_offset;
 490         } else {
 491                 bytes = cundomap->alloc_offset - dundomap->first_offset +
 492                         HAMMER_OFF_LONG_ENCODE(cundomap->next_offset);
 493         }
 494         max_bytes = HAMMER_OFF_SHORT_ENCODE(cundomap->alloc_offset);
 495         KKASSERT(bytes <= max_bytes);
 496         return(bytes);
 497 }
 498
 499 /*
 500  * Return how much of the undo FIFO is available for new records.
 501  */
 502 int64_t
 503 hammer_undo_space(hammer_transaction_t trans)
 504 {
 505         hammer_blockmap_t rootmap;
 506         int64_t max_bytes;
 507
 508         rootmap = &trans->hmp->blockmap[HAMMER_ZONE_UNDO_INDEX];
 509         max_bytes = HAMMER_OFF_SHORT_ENCODE(rootmap->alloc_offset);
 510         return(max_bytes - hammer_undo_used(trans));
 511 }
 512
 513 int64_t
 514 hammer_undo_max(hammer_mount_t hmp)
 515 {
 516         hammer_blockmap_t rootmap;
 517         int64_t max_bytes;
 518
 519         rootmap = &hmp->blockmap[HAMMER_ZONE_UNDO_INDEX];
 520         max_bytes = HAMMER_OFF_SHORT_ENCODE(rootmap->alloc_offset);
 521
 522         return(max_bytes);
 523 }
 524
 525 /*
 526  * Returns 1 if the undo buffer should be reclaimed on release.  The
 527  * only undo buffer we do NOT want to reclaim is the one at the current
 528  * append offset.
 529  */
 530 int
 531 hammer_undo_reclaim(hammer_io_t io)
 532 {
 533         hammer_blockmap_t undomap;
 534         hammer_off_t next_offset;
 535
 536         undomap = &io->hmp->blockmap[HAMMER_ZONE_UNDO_INDEX];
 537         next_offset = undomap->next_offset & ~HAMMER_BUFMASK64;
 538         if (HAMMER_ITOB(io)->zoneX_offset == next_offset)
 539                 return(0);
 540         return(1);
 541 }