sys/vfs/hammer/hammer_recover.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  * $DragonFly: src/sys/vfs/hammer/hammer_recover.c,v 1.29 2008/07/26 05:36:21 dillon Exp $
  35  */
  36
  37 #include "hammer.h"
  38
  39 static int hammer_check_tail_signature(hammer_fifo_tail_t tail,
  40                         hammer_off_t end_off);
  41 static void hammer_recover_copy_undo(hammer_off_t undo_offset,
  42                         char *src, char *dst, int bytes);
  43 #if 0
  44 static void hammer_recover_debug_dump(int w, char *buf, int bytes);
  45 #endif
  46 static int hammer_recover_undo(hammer_mount_t hmp, hammer_volume_t root_volume,
  47                         hammer_fifo_undo_t undo, int bytes);
  48
  49 /*
  50  * Recover a filesystem on mount
  51  *
  52  * NOTE: No information from the root volume has been cached in the
  53  * hammer_mount structure yet, so we need to access the root volume's
  54  * buffer directly.
  55  */
  56 int
  57 hammer_recover(hammer_mount_t hmp, hammer_volume_t root_volume)
  58 {
  59         hammer_blockmap_t rootmap;
  60         hammer_buffer_t buffer;
  61         hammer_off_t scan_offset;
  62         hammer_off_t bytes;
  63         hammer_fifo_tail_t tail;
  64         hammer_fifo_undo_t undo;
  65         hammer_off_t first_offset;
  66         hammer_off_t last_offset;
  67         int error;
  68
  69         /*
  70          * Examine the UNDO FIFO.  If it is empty the filesystem is clean
  71          * and no action need be taken.
  72          */
  73         rootmap = &root_volume->ondisk->vol0_blockmap[HAMMER_ZONE_UNDO_INDEX];
  74
  75         if (rootmap->first_offset == rootmap->next_offset)
  76                 return(0);
  77
  78         first_offset = rootmap->first_offset;
  79         last_offset  = rootmap->next_offset;
  80
  81         if (last_offset >= first_offset) {
  82                 bytes = last_offset - first_offset;
  83         } else {
  84                 bytes = rootmap->alloc_offset - first_offset +
  85                         (last_offset & HAMMER_OFF_LONG_MASK);
  86         }
  87         kprintf("HAMMER(%s) Start Recovery %016llx - %016llx "
  88                 "(%lld bytes of UNDO)%s\n",
  89                 root_volume->ondisk->vol_name,
  90                 first_offset, last_offset,
  91                 bytes,
  92                 (hmp->ronly ? " (RO)" : "(RW)"));
  93         if (bytes > (rootmap->alloc_offset & HAMMER_OFF_LONG_MASK)) {
  94                 kprintf("Undo size is absurd, unable to mount\n");
  95                 return(EIO);
  96         }
  97
  98         /*
  99          * Scan the UNDOs backwards.
 100          */
 101         scan_offset = last_offset;
 102         buffer = NULL;
 103         if (scan_offset > rootmap->alloc_offset) {
 104                 kprintf("HAMMER(%s) UNDO record at %016llx FIFO overflow\n",
 105                         root_volume->ondisk->vol_name,
 106                         scan_offset);
 107                 error = EIO;
 108                 goto done;
 109         }
 110
 111         while ((int64_t)bytes > 0) {
 112                 if (hammer_debug_general & 0x0080)
 113                         kprintf("scan_offset %016llx\n", scan_offset);
 114                 if (scan_offset == HAMMER_ZONE_ENCODE(HAMMER_ZONE_UNDO_INDEX, 0)) {
 115                         scan_offset = rootmap->alloc_offset;
 116                         continue;
 117                 }
 118                 if (scan_offset - sizeof(*tail) <
 119                     HAMMER_ZONE_ENCODE(HAMMER_ZONE_UNDO_INDEX, 0)) {
 120                         kprintf("HAMMER(%s) UNDO record at %016llx FIFO "
 121                                 "underflow\n",
 122                                 root_volume->ondisk->vol_name,
 123                                 scan_offset);
 124                         error = EIO;
 125                         break;
 126                 }
 127                 tail = hammer_bread(hmp, scan_offset - sizeof(*tail),
 128                                     &error, &buffer);
 129                 if (error) {
 130                         kprintf("HAMMER(%s) Unable to read UNDO TAIL "
 131                                 "at %016llx\n",
 132                                 root_volume->ondisk->vol_name,
 133                                 scan_offset - sizeof(*tail));
 134                         break;
 135                 }
 136
 137                 if (hammer_check_tail_signature(tail, scan_offset) != 0) {
 138                         kprintf("HAMMER(%s) Illegal UNDO TAIL signature "
 139                                 "at %016llx\n",
 140                                 root_volume->ondisk->vol_name,
 141                                 scan_offset - sizeof(*tail));
 142                         error = EIO;
 143                         break;
 144                 }
 145                 undo = (void *)((char *)tail + sizeof(*tail) - tail->tail_size);
 146
 147                 error = hammer_recover_undo(hmp, root_volume, undo,
 148                                 HAMMER_BUFSIZE -
 149                                 (int)((char *)undo - (char *)buffer->ondisk));
 150                 if (error) {
 151                         kprintf("HAMMER(%s) UNDO record at %016llx failed\n",
 152                                 root_volume->ondisk->vol_name,
 153                                 scan_offset - tail->tail_size);
 154                         break;
 155                 }
 156                 scan_offset -= tail->tail_size;
 157                 bytes -= tail->tail_size;
 158
 159                 /*
 160                  * If too many dirty buffers have built up we have to flush'm
 161                  * out.  As long as we do not flush out the volume header
 162                  * a crash here should not cause any problems.
 163                  *
 164                  * buffer must be released so the flush can assert that
 165                  * all buffers are idle.
 166                  */
 167                 if (hammer_flusher_meta_limit(hmp)) {
 168                         if (buffer) {
 169                                 hammer_rel_buffer(buffer, 0);
 170                                 buffer = NULL;
 171                         }
 172                         if (hmp->ronly == 0) {
 173                                 hammer_recover_flush_buffers(hmp, root_volume,
 174                                                              0);
 175                                 kprintf("HAMMER(%s) Continuing recovery\n",
 176                                         root_volume->ondisk->vol_name);
 177                         } else {
 178                                 kprintf("HAMMER(%s) Recovery failure: Insufficient buffer cache to hold dirty buffers on read-only mount!\n",
 179                                         root_volume->ondisk->vol_name);
 180                                 error = EIO;
 181                                 break;
 182                         }
 183                 }
 184         }
 185 done:
 186         if (buffer)
 187                 hammer_rel_buffer(buffer, 0);
 188
 189         /*
 190          * After completely flushing all the recovered buffers the volume
 191          * header will also be flushed.  Force the UNDO FIFO to 0-length.
 192          */
 193         if (root_volume->io.recovered == 0) {
 194                 hammer_ref_volume(root_volume);
 195                 root_volume->io.recovered = 1;
 196         }
 197
 198         /*
 199          * Finish up flushing (or discarding) recovered buffers
 200          */
 201         if (error == 0) {
 202                 hammer_modify_volume(NULL, root_volume, NULL, 0);
 203                 rootmap = &root_volume->ondisk->vol0_blockmap[HAMMER_ZONE_UNDO_INDEX];
 204                 rootmap->first_offset = last_offset;
 205                 rootmap->next_offset = last_offset;
 206                 hammer_modify_volume_done(root_volume);
 207                 if (hmp->ronly == 0)
 208                         hammer_recover_flush_buffers(hmp, root_volume, 1);
 209         } else {
 210                 hammer_recover_flush_buffers(hmp, root_volume, -1);
 211         }
 212         kprintf("HAMMER(%s) End Recovery\n", root_volume->ondisk->vol_name);
 213         return (error);
 214 }
 215
 216 static int
 217 hammer_check_tail_signature(hammer_fifo_tail_t tail, hammer_off_t end_off)
 218 {
 219         int max_bytes;
 220
 221         max_bytes = ((end_off - sizeof(*tail)) & HAMMER_BUFMASK);
 222         max_bytes += sizeof(*tail);
 223
 224         /*
 225          * tail overlaps buffer boundary
 226          */
 227         if (((end_off - sizeof(*tail)) ^ (end_off - 1)) & ~HAMMER_BUFMASK64) {
 228                 return(1);
 229         }
 230
 231         /*
 232          * signature check, the tail signature is allowed to be the head
 233          * signature only for 8-byte PADs.
 234          */
 235         switch(tail->tail_signature) {
 236         case HAMMER_TAIL_SIGNATURE:
 237                 break;
 238         case HAMMER_HEAD_SIGNATURE:
 239                 if (tail->tail_type != HAMMER_HEAD_TYPE_PAD ||
 240                     tail->tail_size != sizeof(*tail)) {
 241                         return(2);
 242                 }
 243                 break;
 244         }
 245
 246         /*
 247          * The undo structure must not overlap a buffer boundary.
 248          */
 249         if (tail->tail_size < sizeof(*tail) || tail->tail_size > max_bytes) {
 250                 return(3);
 251         }
 252         return(0);
 253 }
 254
 255 static int
 256 hammer_recover_undo(hammer_mount_t hmp, hammer_volume_t root_volume,
 257                     hammer_fifo_undo_t undo, int bytes)
 258 {
 259         hammer_fifo_tail_t tail;
 260         hammer_volume_t volume;
 261         hammer_buffer_t buffer;
 262         hammer_off_t buf_offset;
 263         int zone;
 264         int error;
 265         int vol_no;
 266         int max_bytes;
 267         u_int32_t offset;
 268         u_int32_t crc;
 269
 270         /*
 271          * Basic sanity checks
 272          */
 273         if (bytes < HAMMER_HEAD_ALIGN) {
 274                 kprintf("HAMMER: Undo alignment error (%d)\n", bytes);
 275                 return(EIO);
 276         }
 277         if (undo->head.hdr_signature != HAMMER_HEAD_SIGNATURE) {
 278                 kprintf("HAMMER: Bad head signature %04x\n",
 279                         undo->head.hdr_signature);
 280                 return(EIO);
 281         }
 282         if (undo->head.hdr_size < HAMMER_HEAD_ALIGN ||
 283             undo->head.hdr_size > bytes) {
 284                 kprintf("HAMMER: Bad size %d\n", bytes);
 285                 return(EIO);
 286         }
 287
 288         /*
 289          * Skip PAD records.  Note that PAD records also do not require
 290          * a tail and may have a truncated structure.
 291          */
 292         if (undo->head.hdr_type == HAMMER_HEAD_TYPE_PAD)
 293                 return(0);
 294
 295         /*
 296          * Check the CRC
 297          */
 298         crc = crc32(undo, HAMMER_FIFO_HEAD_CRCOFF) ^
 299               crc32(&undo->head + 1, undo->head.hdr_size - sizeof(undo->head));
 300         if (undo->head.hdr_crc != crc) {
 301                 kprintf("HAMMER: Undo record CRC failed %08x %08x\n",
 302                         undo->head.hdr_crc, crc);
 303                 return(EIO);
 304         }
 305
 306
 307         /*
 308          * Check the tail
 309          */
 310         bytes = undo->head.hdr_size;
 311         tail = (void *)((char *)undo + bytes - sizeof(*tail));
 312         if (tail->tail_size != undo->head.hdr_size) {
 313                 kprintf("HAMMER: Bad tail size %d\n", tail->tail_size);
 314                 return(EIO);
 315         }
 316         if (tail->tail_type != undo->head.hdr_type) {
 317                 kprintf("HAMMER: Bad tail type %d\n", tail->tail_type);
 318                 return(EIO);
 319         }
 320
 321         /*
 322          * Only process UNDO records
 323          */
 324         if (undo->head.hdr_type != HAMMER_HEAD_TYPE_UNDO)
 325                 return(0);
 326
 327         /*
 328          * Validate the UNDO record.
 329          */
 330         max_bytes = undo->head.hdr_size - sizeof(*undo) - sizeof(*tail);
 331         if (undo->undo_data_bytes < 0 || undo->undo_data_bytes > max_bytes) {
 332                 kprintf("HAMMER: Corrupt UNDO record, undo_data_bytes %d/%d\n",
 333                         undo->undo_data_bytes, max_bytes);
 334                 return(EIO);
 335         }
 336
 337         /*
 338          * The undo offset may only be a zone-1 or zone-2 offset.
 339          *
 340          * Currently we only support a zone-1 offset representing the
 341          * volume header.
 342          */
 343         zone = HAMMER_ZONE_DECODE(undo->undo_offset);
 344         offset = undo->undo_offset & HAMMER_BUFMASK;
 345
 346         if (offset + undo->undo_data_bytes > HAMMER_BUFSIZE) {
 347                 kprintf("HAMMER: Corrupt UNDO record, bad offset\n");
 348                 return (EIO);
 349         }
 350
 351         switch(zone) {
 352         case HAMMER_ZONE_RAW_VOLUME_INDEX:
 353                 vol_no = HAMMER_VOL_DECODE(undo->undo_offset);
 354                 volume = hammer_get_volume(hmp, vol_no, &error);
 355                 if (volume == NULL) {
 356                         kprintf("HAMMER: UNDO record, "
 357                                 "cannot access volume %d\n", vol_no);
 358                         break;
 359                 }
 360                 hammer_modify_volume(NULL, volume, NULL, 0);
 361                 hammer_recover_copy_undo(undo->undo_offset,
 362                                          (char *)(undo + 1),
 363                                          (char *)volume->ondisk + offset,
 364                                          undo->undo_data_bytes);
 365                 hammer_modify_volume_done(volume);
 366
 367                 /*
 368                  * Multiple modifications may be made to the same buffer.
 369                  * Also, the volume header cannot be written out until
 370                  * everything else has been flushed.  This also
 371                  * covers the read-only case by preventing the kernel from
 372                  * flushing the buffer.
 373                  */
 374                 if (volume->io.recovered == 0)
 375                         volume->io.recovered = 1;
 376                 else
 377                         hammer_rel_volume(volume, 0);
 378                 break;
 379         case HAMMER_ZONE_RAW_BUFFER_INDEX:
 380                 buf_offset = undo->undo_offset & ~HAMMER_BUFMASK64;
 381                 buffer = hammer_get_buffer(hmp, buf_offset, HAMMER_BUFSIZE,
 382                                            0, &error);
 383                 if (buffer == NULL) {
 384                         kprintf("HAMMER: UNDO record, "
 385                                 "cannot access buffer %016llx\n",
 386                                 undo->undo_offset);
 387                         break;
 388                 }
 389                 hammer_modify_buffer(NULL, buffer, NULL, 0);
 390                 hammer_recover_copy_undo(undo->undo_offset,
 391                                          (char *)(undo + 1),
 392                                          (char *)buffer->ondisk + offset,
 393                                          undo->undo_data_bytes);
 394                 hammer_modify_buffer_done(buffer);
 395
 396                 /*
 397                  * Multiple modifications may be made to the same buffer,
 398                  * improve performance by delaying the flush.  This also
 399                  * covers the read-only case by preventing the kernel from
 400                  * flushing the buffer.
 401                  */
 402                 if (buffer->io.recovered == 0)
 403                         buffer->io.recovered = 1;
 404                 else
 405                         hammer_rel_buffer(buffer, 0);
 406                 break;
 407         default:
 408                 kprintf("HAMMER: Corrupt UNDO record\n");
 409                 error = EIO;
 410         }
 411         return (error);
 412 }
 413
 414 static void
 415 hammer_recover_copy_undo(hammer_off_t undo_offset,
 416                          char *src, char *dst, int bytes)
 417 {
 418         if (hammer_debug_general & 0x0080)
 419                 kprintf("UNDO %016llx: %d\n", undo_offset, bytes);
 420 #if 0
 421         kprintf("UNDO %016llx:", undo_offset);
 422         hammer_recover_debug_dump(22, dst, bytes);
 423         kprintf("%22s", "to:");
 424         hammer_recover_debug_dump(22, src, bytes);
 425 #endif
 426         bcopy(src, dst, bytes);
 427 }
 428
 429 #if 0
 430
 431 static void
 432 hammer_recover_debug_dump(int w, char *buf, int bytes)
 433 {
 434         int i;
 435
 436         for (i = 0; i < bytes; ++i) {
 437                 if (i && (i & 15) == 0)
 438                         kprintf("\n%*.*s", w, w, "");
 439                 kprintf(" %02x", (unsigned char)buf[i]);
 440         }
 441         kprintf("\n");
 442 }
 443
 444 #endif
 445
 446 /*
 447  * Flush recovered buffers from recovery operations.  The call to this
 448  * routine may be delayed if a read-only mount was made and then later
 449  * upgraded to read-write.
 450  *
 451  * The volume header is always written last.  The UNDO FIFO will be forced
 452  * to zero-length by setting next_offset to first_offset.  This leaves the
 453  * (now stale) UNDO information used to recover the disk available for
 454  * forensic analysis.
 455  *
 456  * final is typically 0 or 1.  The volume header is only written if final
 457  * is 1.  If final is -1 the recovered buffers are discarded instead of
 458  * written and root_volume can also be passed as NULL in that case.
 459  */
 460 static int hammer_recover_flush_volume_callback(hammer_volume_t, void *);
 461 static int hammer_recover_flush_buffer_callback(hammer_buffer_t, void *);
 462
 463 void
 464 hammer_recover_flush_buffers(hammer_mount_t hmp, hammer_volume_t root_volume,
 465                              int final)
 466 {
 467         /*
 468          * Flush the buffers out asynchronously, wait for all the I/O to
 469          * complete, then do it again to destroy the buffer cache buffer
 470          * so it doesn't alias something later on.
 471          */
 472         RB_SCAN(hammer_buf_rb_tree, &hmp->rb_bufs_root, NULL,
 473                 hammer_recover_flush_buffer_callback, &final);
 474         hammer_io_wait_all(hmp, "hmrrcw");
 475         RB_SCAN(hammer_buf_rb_tree, &hmp->rb_bufs_root, NULL,
 476                 hammer_recover_flush_buffer_callback, &final);
 477
 478         /*
 479          * Flush all volume headers except the root volume.  If final < 0
 480          * we discard all volume headers including the root volume.
 481          */
 482         if (final >= 0) {
 483                 RB_SCAN(hammer_vol_rb_tree, &hmp->rb_vols_root, NULL,
 484                         hammer_recover_flush_volume_callback, root_volume);
 485         } else {
 486                 RB_SCAN(hammer_vol_rb_tree, &hmp->rb_vols_root, NULL,
 487                         hammer_recover_flush_volume_callback, NULL);
 488         }
 489
 490         /*
 491          * Finalize the root volume header.
 492          */
 493         if (root_volume && root_volume->io.recovered && final > 0) {
 494                 crit_enter();
 495                 while (hmp->io_running_space > 0)
 496                         tsleep(&hmp->io_running_space, 0, "hmrflx", 0);
 497                 crit_exit();
 498                 root_volume->io.recovered = 0;
 499                 hammer_io_flush(&root_volume->io);
 500                 hammer_rel_volume(root_volume, 0);
 501         }
 502 }
 503
 504 /*
 505  * Callback to flush volume headers.  If discarding data will be NULL and
 506  * all volume headers (including the root volume) will be discarded.
 507  * Otherwise data is the root_volume and we flush all volume headers
 508  * EXCEPT the root_volume.
 509  */
 510 static
 511 int
 512 hammer_recover_flush_volume_callback(hammer_volume_t volume, void *data)
 513 {
 514         hammer_volume_t root_volume = data;
 515
 516         if (volume->io.recovered && volume != root_volume) {
 517                 volume->io.recovered = 0;
 518                 if (root_volume != NULL)
 519                         hammer_io_flush(&volume->io);
 520                 else
 521                         hammer_io_clear_modify(&volume->io, 1);
 522                 hammer_rel_volume(volume, 0);
 523         }
 524         return(0);
 525 }
 526
 527 static
 528 int
 529 hammer_recover_flush_buffer_callback(hammer_buffer_t buffer, void *data)
 530 {
 531         int final = *(int *)data;
 532
 533         if (buffer->io.recovered) {
 534                 buffer->io.recovered = 0;
 535                 buffer->io.reclaim = 1;
 536                 if (final < 0)
 537                         hammer_io_clear_modify(&buffer->io, 1);
 538                 else
 539                         hammer_io_flush(&buffer->io);
 540                 hammer_rel_buffer(buffer, 0);
 541         } else {
 542                 KKASSERT(buffer->io.lock.refs == 0);
 543                 ++hammer_count_refedbufs;
 544                 hammer_ref(&buffer->io.lock);
 545                 buffer->io.reclaim = 1;
 546                 hammer_rel_buffer(buffer, 1);
 547         }
 548         return(0);
 549 }
 550