block/qcow2-snapshot.c

   1 /*
   2  * Block driver for the QCOW version 2 format
   3  *
   4  * Copyright (c) 2004-2006 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24
  25 #include "qemu-common.h"
  26 #include "block/block_int.h"
  27 #include "block/qcow2.h"
  28
  29 typedef struct QEMU_PACKED QCowSnapshotHeader {
  30     /* header is 8 byte aligned */
  31     uint64_t l1_table_offset;
  32
  33     uint32_t l1_size;
  34     uint16_t id_str_size;
  35     uint16_t name_size;
  36
  37     uint32_t date_sec;
  38     uint32_t date_nsec;
  39
  40     uint64_t vm_clock_nsec;
  41
  42     uint32_t vm_state_size;
  43     uint32_t extra_data_size; /* for extension */
  44     /* extra data follows */
  45     /* id_str follows */
  46     /* name follows  */
  47 } QCowSnapshotHeader;
  48
  49 typedef struct QEMU_PACKED QCowSnapshotExtraData {
  50     uint64_t vm_state_size_large;
  51     uint64_t disk_size;
  52 } QCowSnapshotExtraData;
  53
  54 void qcow2_free_snapshots(BlockDriverState *bs)
  55 {
  56     BDRVQcowState *s = bs->opaque;
  57     int i;
  58
  59     for(i = 0; i < s->nb_snapshots; i++) {
  60         g_free(s->snapshots[i].name);
  61         g_free(s->snapshots[i].id_str);
  62     }
  63     g_free(s->snapshots);
  64     s->snapshots = NULL;
  65     s->nb_snapshots = 0;
  66 }
  67
  68 int qcow2_read_snapshots(BlockDriverState *bs)
  69 {
  70     BDRVQcowState *s = bs->opaque;
  71     QCowSnapshotHeader h;
  72     QCowSnapshotExtraData extra;
  73     QCowSnapshot *sn;
  74     int i, id_str_size, name_size;
  75     int64_t offset;
  76     uint32_t extra_data_size;
  77     int ret;
  78
  79     if (!s->nb_snapshots) {
  80         s->snapshots = NULL;
  81         s->snapshots_size = 0;
  82         return 0;
  83     }
  84
  85     offset = s->snapshots_offset;
  86     s->snapshots = g_malloc0(s->nb_snapshots * sizeof(QCowSnapshot));
  87
  88     for(i = 0; i < s->nb_snapshots; i++) {
  89         /* Read statically sized part of the snapshot header */
  90         offset = align_offset(offset, 8);
  91         ret = bdrv_pread(bs->file, offset, &h, sizeof(h));
  92         if (ret < 0) {
  93             goto fail;
  94         }
  95
  96         offset += sizeof(h);
  97         sn = s->snapshots + i;
  98         sn->l1_table_offset = be64_to_cpu(h.l1_table_offset);
  99         sn->l1_size = be32_to_cpu(h.l1_size);
 100         sn->vm_state_size = be32_to_cpu(h.vm_state_size);
 101         sn->date_sec = be32_to_cpu(h.date_sec);
 102         sn->date_nsec = be32_to_cpu(h.date_nsec);
 103         sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec);
 104         extra_data_size = be32_to_cpu(h.extra_data_size);
 105
 106         id_str_size = be16_to_cpu(h.id_str_size);
 107         name_size = be16_to_cpu(h.name_size);
 108
 109         /* Read extra data */
 110         ret = bdrv_pread(bs->file, offset, &extra,
 111                          MIN(sizeof(extra), extra_data_size));
 112         if (ret < 0) {
 113             goto fail;
 114         }
 115         offset += extra_data_size;
 116
 117         if (extra_data_size >= 8) {
 118             sn->vm_state_size = be64_to_cpu(extra.vm_state_size_large);
 119         }
 120
 121         if (extra_data_size >= 16) {
 122             sn->disk_size = be64_to_cpu(extra.disk_size);
 123         } else {
 124             sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
 125         }
 126
 127         /* Read snapshot ID */
 128         sn->id_str = g_malloc(id_str_size + 1);
 129         ret = bdrv_pread(bs->file, offset, sn->id_str, id_str_size);
 130         if (ret < 0) {
 131             goto fail;
 132         }
 133         offset += id_str_size;
 134         sn->id_str[id_str_size] = '\0';
 135
 136         /* Read snapshot name */
 137         sn->name = g_malloc(name_size + 1);
 138         ret = bdrv_pread(bs->file, offset, sn->name, name_size);
 139         if (ret < 0) {
 140             goto fail;
 141         }
 142         offset += name_size;
 143         sn->name[name_size] = '\0';
 144     }
 145
 146     s->snapshots_size = offset - s->snapshots_offset;
 147     return 0;
 148
 149 fail:
 150     qcow2_free_snapshots(bs);
 151     return ret;
 152 }
 153
 154 /* add at the end of the file a new list of snapshots */
 155 static int qcow2_write_snapshots(BlockDriverState *bs)
 156 {
 157     BDRVQcowState *s = bs->opaque;
 158     QCowSnapshot *sn;
 159     QCowSnapshotHeader h;
 160     QCowSnapshotExtraData extra;
 161     int i, name_size, id_str_size, snapshots_size;
 162     struct {
 163         uint32_t nb_snapshots;
 164         uint64_t snapshots_offset;
 165     } QEMU_PACKED header_data;
 166     int64_t offset, snapshots_offset;
 167     int ret;
 168
 169     /* compute the size of the snapshots */
 170     offset = 0;
 171     for(i = 0; i < s->nb_snapshots; i++) {
 172         sn = s->snapshots + i;
 173         offset = align_offset(offset, 8);
 174         offset += sizeof(h);
 175         offset += sizeof(extra);
 176         offset += strlen(sn->id_str);
 177         offset += strlen(sn->name);
 178     }
 179     snapshots_size = offset;
 180
 181     /* Allocate space for the new snapshot list */
 182     snapshots_offset = qcow2_alloc_clusters(bs, snapshots_size);
 183     offset = snapshots_offset;
 184     if (offset < 0) {
 185         return offset;
 186     }
 187     ret = bdrv_flush(bs);
 188     if (ret < 0) {
 189         return ret;
 190     }
 191
 192     /* Write all snapshots to the new list */
 193     for(i = 0; i < s->nb_snapshots; i++) {
 194         sn = s->snapshots + i;
 195         memset(&h, 0, sizeof(h));
 196         h.l1_table_offset = cpu_to_be64(sn->l1_table_offset);
 197         h.l1_size = cpu_to_be32(sn->l1_size);
 198         /* If it doesn't fit in 32 bit, older implementations should treat it
 199          * as a disk-only snapshot rather than truncate the VM state */
 200         if (sn->vm_state_size <= 0xffffffff) {
 201             h.vm_state_size = cpu_to_be32(sn->vm_state_size);
 202         }
 203         h.date_sec = cpu_to_be32(sn->date_sec);
 204         h.date_nsec = cpu_to_be32(sn->date_nsec);
 205         h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec);
 206         h.extra_data_size = cpu_to_be32(sizeof(extra));
 207
 208         memset(&extra, 0, sizeof(extra));
 209         extra.vm_state_size_large = cpu_to_be64(sn->vm_state_size);
 210         extra.disk_size = cpu_to_be64(sn->disk_size);
 211
 212         id_str_size = strlen(sn->id_str);
 213         name_size = strlen(sn->name);
 214         h.id_str_size = cpu_to_be16(id_str_size);
 215         h.name_size = cpu_to_be16(name_size);
 216         offset = align_offset(offset, 8);
 217
 218         ret = bdrv_pwrite(bs->file, offset, &h, sizeof(h));
 219         if (ret < 0) {
 220             goto fail;
 221         }
 222         offset += sizeof(h);
 223
 224         ret = bdrv_pwrite(bs->file, offset, &extra, sizeof(extra));
 225         if (ret < 0) {
 226             goto fail;
 227         }
 228         offset += sizeof(extra);
 229
 230         ret = bdrv_pwrite(bs->file, offset, sn->id_str, id_str_size);
 231         if (ret < 0) {
 232             goto fail;
 233         }
 234         offset += id_str_size;
 235
 236         ret = bdrv_pwrite(bs->file, offset, sn->name, name_size);
 237         if (ret < 0) {
 238             goto fail;
 239         }
 240         offset += name_size;
 241     }
 242
 243     /*
 244      * Update the header to point to the new snapshot table. This requires the
 245      * new table and its refcounts to be stable on disk.
 246      */
 247     ret = bdrv_flush(bs);
 248     if (ret < 0) {
 249         goto fail;
 250     }
 251
 252     QEMU_BUILD_BUG_ON(offsetof(QCowHeader, snapshots_offset) !=
 253         offsetof(QCowHeader, nb_snapshots) + sizeof(header_data.nb_snapshots));
 254
 255     header_data.nb_snapshots        = cpu_to_be32(s->nb_snapshots);
 256     header_data.snapshots_offset    = cpu_to_be64(snapshots_offset);
 257
 258     ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, nb_snapshots),
 259                            &header_data, sizeof(header_data));
 260     if (ret < 0) {
 261         goto fail;
 262     }
 263
 264     /* free the old snapshot table */
 265     qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size);
 266     s->snapshots_offset = snapshots_offset;
 267     s->snapshots_size = snapshots_size;
 268     return 0;
 269
 270 fail:
 271     return ret;
 272 }
 273
 274 static void find_new_snapshot_id(BlockDriverState *bs,
 275                                  char *id_str, int id_str_size)
 276 {
 277     BDRVQcowState *s = bs->opaque;
 278     QCowSnapshot *sn;
 279     int i, id, id_max = 0;
 280
 281     for(i = 0; i < s->nb_snapshots; i++) {
 282         sn = s->snapshots + i;
 283         id = strtoul(sn->id_str, NULL, 10);
 284         if (id > id_max)
 285             id_max = id;
 286     }
 287     snprintf(id_str, id_str_size, "%d", id_max + 1);
 288 }
 289
 290 static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str)
 291 {
 292     BDRVQcowState *s = bs->opaque;
 293     int i;
 294
 295     for(i = 0; i < s->nb_snapshots; i++) {
 296         if (!strcmp(s->snapshots[i].id_str, id_str))
 297             return i;
 298     }
 299     return -1;
 300 }
 301
 302 static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name)
 303 {
 304     BDRVQcowState *s = bs->opaque;
 305     int i, ret;
 306
 307     ret = find_snapshot_by_id(bs, name);
 308     if (ret >= 0)
 309         return ret;
 310     for(i = 0; i < s->nb_snapshots; i++) {
 311         if (!strcmp(s->snapshots[i].name, name))
 312             return i;
 313     }
 314     return -1;
 315 }
 316
 317 /* if no id is provided, a new one is constructed */
 318 int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
 319 {
 320     BDRVQcowState *s = bs->opaque;
 321     QCowSnapshot *new_snapshot_list = NULL;
 322     QCowSnapshot *old_snapshot_list = NULL;
 323     QCowSnapshot sn1, *sn = &sn1;
 324     int i, ret;
 325     uint64_t *l1_table = NULL;
 326     int64_t l1_table_offset;
 327
 328     memset(sn, 0, sizeof(*sn));
 329
 330     /* Generate an ID if it wasn't passed */
 331     if (sn_info->id_str[0] == '\0') {
 332         find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str));
 333     }
 334
 335     /* Check that the ID is unique */
 336     if (find_snapshot_by_id(bs, sn_info->id_str) >= 0) {
 337         return -EEXIST;
 338     }
 339
 340     /* Populate sn with passed data */
 341     sn->id_str = g_strdup(sn_info->id_str);
 342     sn->name = g_strdup(sn_info->name);
 343
 344     sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
 345     sn->vm_state_size = sn_info->vm_state_size;
 346     sn->date_sec = sn_info->date_sec;
 347     sn->date_nsec = sn_info->date_nsec;
 348     sn->vm_clock_nsec = sn_info->vm_clock_nsec;
 349
 350     /* Allocate the L1 table of the snapshot and copy the current one there. */
 351     l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
 352     if (l1_table_offset < 0) {
 353         ret = l1_table_offset;
 354         goto fail;
 355     }
 356
 357     sn->l1_table_offset = l1_table_offset;
 358     sn->l1_size = s->l1_size;
 359
 360     l1_table = g_malloc(s->l1_size * sizeof(uint64_t));
 361     for(i = 0; i < s->l1_size; i++) {
 362         l1_table[i] = cpu_to_be64(s->l1_table[i]);
 363     }
 364
 365     ret = bdrv_pwrite(bs->file, sn->l1_table_offset, l1_table,
 366                       s->l1_size * sizeof(uint64_t));
 367     if (ret < 0) {
 368         goto fail;
 369     }
 370
 371     g_free(l1_table);
 372     l1_table = NULL;
 373
 374     /*
 375      * Increase the refcounts of all clusters and make sure everything is
 376      * stable on disk before updating the snapshot table to contain a pointer
 377      * to the new L1 table.
 378      */
 379     ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
 380     if (ret < 0) {
 381         goto fail;
 382     }
 383
 384     /* Append the new snapshot to the snapshot list */
 385     new_snapshot_list = g_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
 386     if (s->snapshots) {
 387         memcpy(new_snapshot_list, s->snapshots,
 388                s->nb_snapshots * sizeof(QCowSnapshot));
 389         old_snapshot_list = s->snapshots;
 390     }
 391     s->snapshots = new_snapshot_list;
 392     s->snapshots[s->nb_snapshots++] = *sn;
 393
 394     ret = qcow2_write_snapshots(bs);
 395     if (ret < 0) {
 396         g_free(s->snapshots);
 397         s->snapshots = old_snapshot_list;
 398         goto fail;
 399     }
 400
 401     g_free(old_snapshot_list);
 402
 403 #ifdef DEBUG_ALLOC
 404     {
 405       BdrvCheckResult result = {0};
 406       qcow2_check_refcounts(bs, &result, 0);
 407     }
 408 #endif
 409     return 0;
 410
 411 fail:
 412     g_free(sn->id_str);
 413     g_free(sn->name);
 414     g_free(l1_table);
 415
 416     return ret;
 417 }
 418
 419 /* copy the snapshot 'snapshot_name' into the current disk image */
 420 int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
 421 {
 422     BDRVQcowState *s = bs->opaque;
 423     QCowSnapshot *sn;
 424     int i, snapshot_index;
 425     int cur_l1_bytes, sn_l1_bytes;
 426     int ret;
 427     uint64_t *sn_l1_table = NULL;
 428
 429     /* Search the snapshot */
 430     snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
 431     if (snapshot_index < 0) {
 432         return -ENOENT;
 433     }
 434     sn = &s->snapshots[snapshot_index];
 435
 436     if (sn->disk_size != bs->total_sectors * BDRV_SECTOR_SIZE) {
 437         error_report("qcow2: Loading snapshots with different disk "
 438             "size is not implemented");
 439         ret = -ENOTSUP;
 440         goto fail;
 441     }
 442
 443     /*
 444      * Make sure that the current L1 table is big enough to contain the whole
 445      * L1 table of the snapshot. If the snapshot L1 table is smaller, the
 446      * current one must be padded with zeros.
 447      */
 448     ret = qcow2_grow_l1_table(bs, sn->l1_size, true);
 449     if (ret < 0) {
 450         goto fail;
 451     }
 452
 453     cur_l1_bytes = s->l1_size * sizeof(uint64_t);
 454     sn_l1_bytes = sn->l1_size * sizeof(uint64_t);
 455
 456     /*
 457      * Copy the snapshot L1 table to the current L1 table.
 458      *
 459      * Before overwriting the old current L1 table on disk, make sure to
 460      * increase all refcounts for the clusters referenced by the new one.
 461      * Decrease the refcount referenced by the old one only when the L1
 462      * table is overwritten.
 463      */
 464     sn_l1_table = g_malloc0(cur_l1_bytes);
 465
 466     ret = bdrv_pread(bs->file, sn->l1_table_offset, sn_l1_table, sn_l1_bytes);
 467     if (ret < 0) {
 468         goto fail;
 469     }
 470
 471     ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset,
 472                                          sn->l1_size, 1);
 473     if (ret < 0) {
 474         goto fail;
 475     }
 476
 477     ret = bdrv_pwrite_sync(bs->file, s->l1_table_offset, sn_l1_table,
 478                            cur_l1_bytes);
 479     if (ret < 0) {
 480         goto fail;
 481     }
 482
 483     /*
 484      * Decrease refcount of clusters of current L1 table.
 485      *
 486      * At this point, the in-memory s->l1_table points to the old L1 table,
 487      * whereas on disk we already have the new one.
 488      *
 489      * qcow2_update_snapshot_refcount special cases the current L1 table to use
 490      * the in-memory data instead of really using the offset to load a new one,
 491      * which is why this works.
 492      */
 493     ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
 494                                          s->l1_size, -1);
 495
 496     /*
 497      * Now update the in-memory L1 table to be in sync with the on-disk one. We
 498      * need to do this even if updating refcounts failed.
 499      */
 500     for(i = 0;i < s->l1_size; i++) {
 501         s->l1_table[i] = be64_to_cpu(sn_l1_table[i]);
 502     }
 503
 504     if (ret < 0) {
 505         goto fail;
 506     }
 507
 508     g_free(sn_l1_table);
 509     sn_l1_table = NULL;
 510
 511     /*
 512      * Update QCOW_OFLAG_COPIED in the active L1 table (it may have changed
 513      * when we decreased the refcount of the old snapshot.
 514      */
 515     ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
 516     if (ret < 0) {
 517         goto fail;
 518     }
 519
 520 #ifdef DEBUG_ALLOC
 521     {
 522         BdrvCheckResult result = {0};
 523         qcow2_check_refcounts(bs, &result, 0);
 524     }
 525 #endif
 526     return 0;
 527
 528 fail:
 529     g_free(sn_l1_table);
 530     return ret;
 531 }
 532
 533 int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
 534 {
 535     BDRVQcowState *s = bs->opaque;
 536     QCowSnapshot sn;
 537     int snapshot_index, ret;
 538
 539     /* Search the snapshot */
 540     snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
 541     if (snapshot_index < 0) {
 542         return -ENOENT;
 543     }
 544     sn = s->snapshots[snapshot_index];
 545
 546     /* Remove it from the snapshot list */
 547     memmove(s->snapshots + snapshot_index,
 548             s->snapshots + snapshot_index + 1,
 549             (s->nb_snapshots - snapshot_index - 1) * sizeof(sn));
 550     s->nb_snapshots--;
 551     ret = qcow2_write_snapshots(bs);
 552     if (ret < 0) {
 553         return ret;
 554     }
 555
 556     /*
 557      * The snapshot is now unused, clean up. If we fail after this point, we
 558      * won't recover but just leak clusters.
 559      */
 560     g_free(sn.id_str);
 561     g_free(sn.name);
 562
 563     /*
 564      * Now decrease the refcounts of clusters referenced by the snapshot and
 565      * free the L1 table.
 566      */
 567     ret = qcow2_update_snapshot_refcount(bs, sn.l1_table_offset,
 568                                          sn.l1_size, -1);
 569     if (ret < 0) {
 570         return ret;
 571     }
 572     qcow2_free_clusters(bs, sn.l1_table_offset, sn.l1_size * sizeof(uint64_t));
 573
 574     /* must update the copied flag on the current cluster offsets */
 575     ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
 576     if (ret < 0) {
 577         return ret;
 578     }
 579
 580 #ifdef DEBUG_ALLOC
 581     {
 582         BdrvCheckResult result = {0};
 583         qcow2_check_refcounts(bs, &result, 0);
 584     }
 585 #endif
 586     return 0;
 587 }
 588
 589 int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
 590 {
 591     BDRVQcowState *s = bs->opaque;
 592     QEMUSnapshotInfo *sn_tab, *sn_info;
 593     QCowSnapshot *sn;
 594     int i;
 595
 596     if (!s->nb_snapshots) {
 597         *psn_tab = NULL;
 598         return s->nb_snapshots;
 599     }
 600
 601     sn_tab = g_malloc0(s->nb_snapshots * sizeof(QEMUSnapshotInfo));
 602     for(i = 0; i < s->nb_snapshots; i++) {
 603         sn_info = sn_tab + i;
 604         sn = s->snapshots + i;
 605         pstrcpy(sn_info->id_str, sizeof(sn_info->id_str),
 606                 sn->id_str);
 607         pstrcpy(sn_info->name, sizeof(sn_info->name),
 608                 sn->name);
 609         sn_info->vm_state_size = sn->vm_state_size;
 610         sn_info->date_sec = sn->date_sec;
 611         sn_info->date_nsec = sn->date_nsec;
 612         sn_info->vm_clock_nsec = sn->vm_clock_nsec;
 613     }
 614     *psn_tab = sn_tab;
 615     return s->nb_snapshots;
 616 }
 617
 618 int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name)
 619 {
 620     int i, snapshot_index;
 621     BDRVQcowState *s = bs->opaque;
 622     QCowSnapshot *sn;
 623     uint64_t *new_l1_table;
 624     int new_l1_bytes;
 625     int ret;
 626
 627     assert(bs->read_only);
 628
 629     /* Search the snapshot */
 630     snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_name);
 631     if (snapshot_index < 0) {
 632         return -ENOENT;
 633     }
 634     sn = &s->snapshots[snapshot_index];
 635
 636     /* Allocate and read in the snapshot's L1 table */
 637     new_l1_bytes = s->l1_size * sizeof(uint64_t);
 638     new_l1_table = g_malloc0(align_offset(new_l1_bytes, 512));
 639
 640     ret = bdrv_pread(bs->file, sn->l1_table_offset, new_l1_table, new_l1_bytes);
 641     if (ret < 0) {
 642         g_free(new_l1_table);
 643         return ret;
 644     }
 645
 646     /* Switch the L1 table */
 647     g_free(s->l1_table);
 648
 649     s->l1_size = sn->l1_size;
 650     s->l1_table_offset = sn->l1_table_offset;
 651     s->l1_table = new_l1_table;
 652
 653     for(i = 0;i < s->l1_size; i++) {
 654         be64_to_cpus(&s->l1_table[i]);
 655     }
 656
 657     return 0;
 658 }