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_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     bdrv_flush(bs->file);
 184     offset = snapshots_offset;
 185     if (offset < 0) {
 186         return offset;
 187     }
 188
 189     /* Write all snapshots to the new list */
 190     for(i = 0; i < s->nb_snapshots; i++) {
 191         sn = s->snapshots + i;
 192         memset(&h, 0, sizeof(h));
 193         h.l1_table_offset = cpu_to_be64(sn->l1_table_offset);
 194         h.l1_size = cpu_to_be32(sn->l1_size);
 195         /* If it doesn't fit in 32 bit, older implementations should treat it
 196          * as a disk-only snapshot rather than truncate the VM state */
 197         if (sn->vm_state_size <= 0xffffffff) {
 198             h.vm_state_size = cpu_to_be32(sn->vm_state_size);
 199         }
 200         h.date_sec = cpu_to_be32(sn->date_sec);
 201         h.date_nsec = cpu_to_be32(sn->date_nsec);
 202         h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec);
 203         h.extra_data_size = cpu_to_be32(sizeof(extra));
 204
 205         memset(&extra, 0, sizeof(extra));
 206         extra.vm_state_size_large = cpu_to_be64(sn->vm_state_size);
 207         extra.disk_size = cpu_to_be64(sn->disk_size);
 208
 209         id_str_size = strlen(sn->id_str);
 210         name_size = strlen(sn->name);
 211         h.id_str_size = cpu_to_be16(id_str_size);
 212         h.name_size = cpu_to_be16(name_size);
 213         offset = align_offset(offset, 8);
 214
 215         ret = bdrv_pwrite(bs->file, offset, &h, sizeof(h));
 216         if (ret < 0) {
 217             goto fail;
 218         }
 219         offset += sizeof(h);
 220
 221         ret = bdrv_pwrite(bs->file, offset, &extra, sizeof(extra));
 222         if (ret < 0) {
 223             goto fail;
 224         }
 225         offset += sizeof(extra);
 226
 227         ret = bdrv_pwrite(bs->file, offset, sn->id_str, id_str_size);
 228         if (ret < 0) {
 229             goto fail;
 230         }
 231         offset += id_str_size;
 232
 233         ret = bdrv_pwrite(bs->file, offset, sn->name, name_size);
 234         if (ret < 0) {
 235             goto fail;
 236         }
 237         offset += name_size;
 238     }
 239
 240     /*
 241      * Update the header to point to the new snapshot table. This requires the
 242      * new table and its refcounts to be stable on disk.
 243      */
 244     ret = bdrv_flush(bs);
 245     if (ret < 0) {
 246         goto fail;
 247     }
 248
 249     QEMU_BUILD_BUG_ON(offsetof(QCowHeader, snapshots_offset) !=
 250         offsetof(QCowHeader, nb_snapshots) + sizeof(header_data.nb_snapshots));
 251
 252     header_data.nb_snapshots        = cpu_to_be32(s->nb_snapshots);
 253     header_data.snapshots_offset    = cpu_to_be64(snapshots_offset);
 254
 255     ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, nb_snapshots),
 256                            &header_data, sizeof(header_data));
 257     if (ret < 0) {
 258         goto fail;
 259     }
 260
 261     /* free the old snapshot table */
 262     qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size);
 263     s->snapshots_offset = snapshots_offset;
 264     s->snapshots_size = snapshots_size;
 265     return 0;
 266
 267 fail:
 268     return ret;
 269 }
 270
 271 static void find_new_snapshot_id(BlockDriverState *bs,
 272                                  char *id_str, int id_str_size)
 273 {
 274     BDRVQcowState *s = bs->opaque;
 275     QCowSnapshot *sn;
 276     int i, id, id_max = 0;
 277
 278     for(i = 0; i < s->nb_snapshots; i++) {
 279         sn = s->snapshots + i;
 280         id = strtoul(sn->id_str, NULL, 10);
 281         if (id > id_max)
 282             id_max = id;
 283     }
 284     snprintf(id_str, id_str_size, "%d", id_max + 1);
 285 }
 286
 287 static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str)
 288 {
 289     BDRVQcowState *s = bs->opaque;
 290     int i;
 291
 292     for(i = 0; i < s->nb_snapshots; i++) {
 293         if (!strcmp(s->snapshots[i].id_str, id_str))
 294             return i;
 295     }
 296     return -1;
 297 }
 298
 299 static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name)
 300 {
 301     BDRVQcowState *s = bs->opaque;
 302     int i, ret;
 303
 304     ret = find_snapshot_by_id(bs, name);
 305     if (ret >= 0)
 306         return ret;
 307     for(i = 0; i < s->nb_snapshots; i++) {
 308         if (!strcmp(s->snapshots[i].name, name))
 309             return i;
 310     }
 311     return -1;
 312 }
 313
 314 /* if no id is provided, a new one is constructed */
 315 int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
 316 {
 317     BDRVQcowState *s = bs->opaque;
 318     QCowSnapshot *new_snapshot_list = NULL;
 319     QCowSnapshot *old_snapshot_list = NULL;
 320     QCowSnapshot sn1, *sn = &sn1;
 321     int i, ret;
 322     uint64_t *l1_table = NULL;
 323     int64_t l1_table_offset;
 324
 325     memset(sn, 0, sizeof(*sn));
 326
 327     /* Generate an ID if it wasn't passed */
 328     if (sn_info->id_str[0] == '\0') {
 329         find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str));
 330     }
 331
 332     /* Check that the ID is unique */
 333     if (find_snapshot_by_id(bs, sn_info->id_str) >= 0) {
 334         return -EEXIST;
 335     }
 336
 337     /* Populate sn with passed data */
 338     sn->id_str = g_strdup(sn_info->id_str);
 339     sn->name = g_strdup(sn_info->name);
 340
 341     sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
 342     sn->vm_state_size = sn_info->vm_state_size;
 343     sn->date_sec = sn_info->date_sec;
 344     sn->date_nsec = sn_info->date_nsec;
 345     sn->vm_clock_nsec = sn_info->vm_clock_nsec;
 346
 347     /* Allocate the L1 table of the snapshot and copy the current one there. */
 348     l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
 349     if (l1_table_offset < 0) {
 350         ret = l1_table_offset;
 351         goto fail;
 352     }
 353
 354     sn->l1_table_offset = l1_table_offset;
 355     sn->l1_size = s->l1_size;
 356
 357     l1_table = g_malloc(s->l1_size * sizeof(uint64_t));
 358     for(i = 0; i < s->l1_size; i++) {
 359         l1_table[i] = cpu_to_be64(s->l1_table[i]);
 360     }
 361
 362     ret = bdrv_pwrite(bs->file, sn->l1_table_offset, l1_table,
 363                       s->l1_size * sizeof(uint64_t));
 364     if (ret < 0) {
 365         goto fail;
 366     }
 367
 368     g_free(l1_table);
 369     l1_table = NULL;
 370
 371     /*
 372      * Increase the refcounts of all clusters and make sure everything is
 373      * stable on disk before updating the snapshot table to contain a pointer
 374      * to the new L1 table.
 375      */
 376     ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
 377     if (ret < 0) {
 378         goto fail;
 379     }
 380
 381     ret = bdrv_flush(bs);
 382     if (ret < 0) {
 383         goto fail;
 384     }
 385
 386     /* Append the new snapshot to the snapshot list */
 387     new_snapshot_list = g_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
 388     if (s->snapshots) {
 389         memcpy(new_snapshot_list, s->snapshots,
 390                s->nb_snapshots * sizeof(QCowSnapshot));
 391         old_snapshot_list = s->snapshots;
 392     }
 393     s->snapshots = new_snapshot_list;
 394     s->snapshots[s->nb_snapshots++] = *sn;
 395
 396     ret = qcow2_write_snapshots(bs);
 397     if (ret < 0) {
 398         g_free(s->snapshots);
 399         s->snapshots = old_snapshot_list;
 400         goto fail;
 401     }
 402
 403     g_free(old_snapshot_list);
 404
 405 #ifdef DEBUG_ALLOC
 406     {
 407       BdrvCheckResult result = {0};
 408       qcow2_check_refcounts(bs, &result, 0);
 409     }
 410 #endif
 411     return 0;
 412
 413 fail:
 414     g_free(sn->id_str);
 415     g_free(sn->name);
 416     g_free(l1_table);
 417
 418     return ret;
 419 }
 420
 421 /* copy the snapshot 'snapshot_name' into the current disk image */
 422 int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
 423 {
 424     BDRVQcowState *s = bs->opaque;
 425     QCowSnapshot *sn;
 426     int i, snapshot_index;
 427     int cur_l1_bytes, sn_l1_bytes;
 428     int ret;
 429     uint64_t *sn_l1_table = NULL;
 430
 431     /* Search the snapshot */
 432     snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
 433     if (snapshot_index < 0) {
 434         return -ENOENT;
 435     }
 436     sn = &s->snapshots[snapshot_index];
 437
 438     if (sn->disk_size != bs->total_sectors * BDRV_SECTOR_SIZE) {
 439         error_report("qcow2: Loading snapshots with different disk "
 440             "size is not implemented");
 441         ret = -ENOTSUP;
 442         goto fail;
 443     }
 444
 445     /*
 446      * Make sure that the current L1 table is big enough to contain the whole
 447      * L1 table of the snapshot. If the snapshot L1 table is smaller, the
 448      * current one must be padded with zeros.
 449      */
 450     ret = qcow2_grow_l1_table(bs, sn->l1_size, true);
 451     if (ret < 0) {
 452         goto fail;
 453     }
 454
 455     cur_l1_bytes = s->l1_size * sizeof(uint64_t);
 456     sn_l1_bytes = sn->l1_size * sizeof(uint64_t);
 457
 458     /*
 459      * Copy the snapshot L1 table to the current L1 table.
 460      *
 461      * Before overwriting the old current L1 table on disk, make sure to
 462      * increase all refcounts for the clusters referenced by the new one.
 463      * Decrease the refcount referenced by the old one only when the L1
 464      * table is overwritten.
 465      */
 466     sn_l1_table = g_malloc0(cur_l1_bytes);
 467
 468     ret = bdrv_pread(bs->file, sn->l1_table_offset, sn_l1_table, sn_l1_bytes);
 469     if (ret < 0) {
 470         goto fail;
 471     }
 472
 473     ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset,
 474                                          sn->l1_size, 1);
 475     if (ret < 0) {
 476         goto fail;
 477     }
 478
 479     ret = bdrv_pwrite_sync(bs->file, s->l1_table_offset, sn_l1_table,
 480                            cur_l1_bytes);
 481     if (ret < 0) {
 482         goto fail;
 483     }
 484
 485     /*
 486      * Decrease refcount of clusters of current L1 table.
 487      *
 488      * At this point, the in-memory s->l1_table points to the old L1 table,
 489      * whereas on disk we already have the new one.
 490      *
 491      * qcow2_update_snapshot_refcount special cases the current L1 table to use
 492      * the in-memory data instead of really using the offset to load a new one,
 493      * which is why this works.
 494      */
 495     ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset,
 496                                          s->l1_size, -1);
 497
 498     /*
 499      * Now update the in-memory L1 table to be in sync with the on-disk one. We
 500      * need to do this even if updating refcounts failed.
 501      */
 502     for(i = 0;i < s->l1_size; i++) {
 503         s->l1_table[i] = be64_to_cpu(sn_l1_table[i]);
 504     }
 505
 506     if (ret < 0) {
 507         goto fail;
 508     }
 509
 510     g_free(sn_l1_table);
 511     sn_l1_table = NULL;
 512
 513     /*
 514      * Update QCOW_OFLAG_COPIED in the active L1 table (it may have changed
 515      * when we decreased the refcount of the old snapshot.
 516      */
 517     ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
 518     if (ret < 0) {
 519         goto fail;
 520     }
 521
 522 #ifdef DEBUG_ALLOC
 523     {
 524         BdrvCheckResult result = {0};
 525         qcow2_check_refcounts(bs, &result, 0);
 526     }
 527 #endif
 528     return 0;
 529
 530 fail:
 531     g_free(sn_l1_table);
 532     return ret;
 533 }
 534
 535 int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
 536 {
 537     BDRVQcowState *s = bs->opaque;
 538     QCowSnapshot sn;
 539     int snapshot_index, ret;
 540
 541     /* Search the snapshot */
 542     snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
 543     if (snapshot_index < 0) {
 544         return -ENOENT;
 545     }
 546     sn = s->snapshots[snapshot_index];
 547
 548     /* Remove it from the snapshot list */
 549     memmove(s->snapshots + snapshot_index,
 550             s->snapshots + snapshot_index + 1,
 551             (s->nb_snapshots - snapshot_index - 1) * sizeof(sn));
 552     s->nb_snapshots--;
 553     ret = qcow2_write_snapshots(bs);
 554     if (ret < 0) {
 555         return ret;
 556     }
 557
 558     /*
 559      * The snapshot is now unused, clean up. If we fail after this point, we
 560      * won't recover but just leak clusters.
 561      */
 562     g_free(sn.id_str);
 563     g_free(sn.name);
 564
 565     /*
 566      * Now decrease the refcounts of clusters referenced by the snapshot and
 567      * free the L1 table.
 568      */
 569     ret = qcow2_update_snapshot_refcount(bs, sn.l1_table_offset,
 570                                          sn.l1_size, -1);
 571     if (ret < 0) {
 572         return ret;
 573     }
 574     qcow2_free_clusters(bs, sn.l1_table_offset, sn.l1_size * sizeof(uint64_t));
 575
 576     /* must update the copied flag on the current cluster offsets */
 577     ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
 578     if (ret < 0) {
 579         return ret;
 580     }
 581
 582 #ifdef DEBUG_ALLOC
 583     {
 584         BdrvCheckResult result = {0};
 585         qcow2_check_refcounts(bs, &result, 0);
 586     }
 587 #endif
 588     return 0;
 589 }
 590
 591 int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
 592 {
 593     BDRVQcowState *s = bs->opaque;
 594     QEMUSnapshotInfo *sn_tab, *sn_info;
 595     QCowSnapshot *sn;
 596     int i;
 597
 598     if (!s->nb_snapshots) {
 599         *psn_tab = NULL;
 600         return s->nb_snapshots;
 601     }
 602
 603     sn_tab = g_malloc0(s->nb_snapshots * sizeof(QEMUSnapshotInfo));
 604     for(i = 0; i < s->nb_snapshots; i++) {
 605         sn_info = sn_tab + i;
 606         sn = s->snapshots + i;
 607         pstrcpy(sn_info->id_str, sizeof(sn_info->id_str),
 608                 sn->id_str);
 609         pstrcpy(sn_info->name, sizeof(sn_info->name),
 610                 sn->name);
 611         sn_info->vm_state_size = sn->vm_state_size;
 612         sn_info->date_sec = sn->date_sec;
 613         sn_info->date_nsec = sn->date_nsec;
 614         sn_info->vm_clock_nsec = sn->vm_clock_nsec;
 615     }
 616     *psn_tab = sn_tab;
 617     return s->nb_snapshots;
 618 }
 619
 620 int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name)
 621 {
 622     int i, snapshot_index;
 623     BDRVQcowState *s = bs->opaque;
 624     QCowSnapshot *sn;
 625     uint64_t *new_l1_table;
 626     int new_l1_bytes;
 627     int ret;
 628
 629     assert(bs->read_only);
 630
 631     /* Search the snapshot */
 632     snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_name);
 633     if (snapshot_index < 0) {
 634         return -ENOENT;
 635     }
 636     sn = &s->snapshots[snapshot_index];
 637
 638     /* Allocate and read in the snapshot's L1 table */
 639     new_l1_bytes = s->l1_size * sizeof(uint64_t);
 640     new_l1_table = g_malloc0(align_offset(new_l1_bytes, 512));
 641
 642     ret = bdrv_pread(bs->file, sn->l1_table_offset, new_l1_table, new_l1_bytes);
 643     if (ret < 0) {
 644         g_free(new_l1_table);
 645         return ret;
 646     }
 647
 648     /* Switch the L1 table */
 649     g_free(s->l1_table);
 650
 651     s->l1_size = sn->l1_size;
 652     s->l1_table_offset = sn->l1_table_offset;
 653     s->l1_table = new_l1_table;
 654
 655     for(i = 0;i < s->l1_size; i++) {
 656         be64_to_cpus(&s->l1_table[i]);
 657     }
 658
 659     return 0;
 660 }