| /* |
| * Block driver for the QCOW version 2 format |
| * |
| * Copyright (c) 2004-2006 Fabrice Bellard |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining a copy |
| * of this software and associated documentation files (the "Software"), to deal |
| * in the Software without restriction, including without limitation the rights |
| * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| * copies of the Software, and to permit persons to whom the Software is |
| * furnished to do so, subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be included in |
| * all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| * THE SOFTWARE. |
| */ |
| |
| #include "qemu-common.h" |
| #include "block/block_int.h" |
| #include "block/qcow2.h" |
| #include "qemu/error-report.h" |
| |
| void qcow2_free_snapshots(BlockDriverState *bs) |
| { |
| BDRVQcowState *s = bs->opaque; |
| int i; |
| |
| for(i = 0; i < s->nb_snapshots; i++) { |
| g_free(s->snapshots[i].name); |
| g_free(s->snapshots[i].id_str); |
| } |
| g_free(s->snapshots); |
| s->snapshots = NULL; |
| s->nb_snapshots = 0; |
| } |
| |
| int qcow2_read_snapshots(BlockDriverState *bs) |
| { |
| BDRVQcowState *s = bs->opaque; |
| QCowSnapshotHeader h; |
| QCowSnapshotExtraData extra; |
| QCowSnapshot *sn; |
| int i, id_str_size, name_size; |
| int64_t offset; |
| uint32_t extra_data_size; |
| int ret; |
| |
| if (!s->nb_snapshots) { |
| s->snapshots = NULL; |
| s->snapshots_size = 0; |
| return 0; |
| } |
| |
| offset = s->snapshots_offset; |
| s->snapshots = g_new0(QCowSnapshot, s->nb_snapshots); |
| |
| for(i = 0; i < s->nb_snapshots; i++) { |
| /* Read statically sized part of the snapshot header */ |
| offset = align_offset(offset, 8); |
| ret = bdrv_pread(bs->file, offset, &h, sizeof(h)); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| offset += sizeof(h); |
| sn = s->snapshots + i; |
| sn->l1_table_offset = be64_to_cpu(h.l1_table_offset); |
| sn->l1_size = be32_to_cpu(h.l1_size); |
| sn->vm_state_size = be32_to_cpu(h.vm_state_size); |
| sn->date_sec = be32_to_cpu(h.date_sec); |
| sn->date_nsec = be32_to_cpu(h.date_nsec); |
| sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec); |
| extra_data_size = be32_to_cpu(h.extra_data_size); |
| |
| id_str_size = be16_to_cpu(h.id_str_size); |
| name_size = be16_to_cpu(h.name_size); |
| |
| /* Read extra data */ |
| ret = bdrv_pread(bs->file, offset, &extra, |
| MIN(sizeof(extra), extra_data_size)); |
| if (ret < 0) { |
| goto fail; |
| } |
| offset += extra_data_size; |
| |
| if (extra_data_size >= 8) { |
| sn->vm_state_size = be64_to_cpu(extra.vm_state_size_large); |
| } |
| |
| if (extra_data_size >= 16) { |
| sn->disk_size = be64_to_cpu(extra.disk_size); |
| } else { |
| sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE; |
| } |
| |
| /* Read snapshot ID */ |
| sn->id_str = g_malloc(id_str_size + 1); |
| ret = bdrv_pread(bs->file, offset, sn->id_str, id_str_size); |
| if (ret < 0) { |
| goto fail; |
| } |
| offset += id_str_size; |
| sn->id_str[id_str_size] = '\0'; |
| |
| /* Read snapshot name */ |
| sn->name = g_malloc(name_size + 1); |
| ret = bdrv_pread(bs->file, offset, sn->name, name_size); |
| if (ret < 0) { |
| goto fail; |
| } |
| offset += name_size; |
| sn->name[name_size] = '\0'; |
| |
| if (offset - s->snapshots_offset > QCOW_MAX_SNAPSHOTS_SIZE) { |
| ret = -EFBIG; |
| goto fail; |
| } |
| } |
| |
| assert(offset - s->snapshots_offset <= INT_MAX); |
| s->snapshots_size = offset - s->snapshots_offset; |
| return 0; |
| |
| fail: |
| qcow2_free_snapshots(bs); |
| return ret; |
| } |
| |
| /* add at the end of the file a new list of snapshots */ |
| static int qcow2_write_snapshots(BlockDriverState *bs) |
| { |
| BDRVQcowState *s = bs->opaque; |
| QCowSnapshot *sn; |
| QCowSnapshotHeader h; |
| QCowSnapshotExtraData extra; |
| int i, name_size, id_str_size, snapshots_size; |
| struct { |
| uint32_t nb_snapshots; |
| uint64_t snapshots_offset; |
| } QEMU_PACKED header_data; |
| int64_t offset, snapshots_offset = 0; |
| int ret; |
| |
| /* compute the size of the snapshots */ |
| offset = 0; |
| for(i = 0; i < s->nb_snapshots; i++) { |
| sn = s->snapshots + i; |
| offset = align_offset(offset, 8); |
| offset += sizeof(h); |
| offset += sizeof(extra); |
| offset += strlen(sn->id_str); |
| offset += strlen(sn->name); |
| |
| if (offset > QCOW_MAX_SNAPSHOTS_SIZE) { |
| ret = -EFBIG; |
| goto fail; |
| } |
| } |
| |
| assert(offset <= INT_MAX); |
| snapshots_size = offset; |
| |
| /* Allocate space for the new snapshot list */ |
| snapshots_offset = qcow2_alloc_clusters(bs, snapshots_size); |
| offset = snapshots_offset; |
| if (offset < 0) { |
| ret = offset; |
| goto fail; |
| } |
| ret = bdrv_flush(bs); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| /* The snapshot list position has not yet been updated, so these clusters |
| * must indeed be completely free */ |
| ret = qcow2_pre_write_overlap_check(bs, 0, offset, snapshots_size); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| |
| /* Write all snapshots to the new list */ |
| for(i = 0; i < s->nb_snapshots; i++) { |
| sn = s->snapshots + i; |
| memset(&h, 0, sizeof(h)); |
| h.l1_table_offset = cpu_to_be64(sn->l1_table_offset); |
| h.l1_size = cpu_to_be32(sn->l1_size); |
| /* If it doesn't fit in 32 bit, older implementations should treat it |
| * as a disk-only snapshot rather than truncate the VM state */ |
| if (sn->vm_state_size <= 0xffffffff) { |
| h.vm_state_size = cpu_to_be32(sn->vm_state_size); |
| } |
| h.date_sec = cpu_to_be32(sn->date_sec); |
| h.date_nsec = cpu_to_be32(sn->date_nsec); |
| h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec); |
| h.extra_data_size = cpu_to_be32(sizeof(extra)); |
| |
| memset(&extra, 0, sizeof(extra)); |
| extra.vm_state_size_large = cpu_to_be64(sn->vm_state_size); |
| extra.disk_size = cpu_to_be64(sn->disk_size); |
| |
| id_str_size = strlen(sn->id_str); |
| name_size = strlen(sn->name); |
| assert(id_str_size <= UINT16_MAX && name_size <= UINT16_MAX); |
| h.id_str_size = cpu_to_be16(id_str_size); |
| h.name_size = cpu_to_be16(name_size); |
| offset = align_offset(offset, 8); |
| |
| ret = bdrv_pwrite(bs->file, offset, &h, sizeof(h)); |
| if (ret < 0) { |
| goto fail; |
| } |
| offset += sizeof(h); |
| |
| ret = bdrv_pwrite(bs->file, offset, &extra, sizeof(extra)); |
| if (ret < 0) { |
| goto fail; |
| } |
| offset += sizeof(extra); |
| |
| ret = bdrv_pwrite(bs->file, offset, sn->id_str, id_str_size); |
| if (ret < 0) { |
| goto fail; |
| } |
| offset += id_str_size; |
| |
| ret = bdrv_pwrite(bs->file, offset, sn->name, name_size); |
| if (ret < 0) { |
| goto fail; |
| } |
| offset += name_size; |
| } |
| |
| /* |
| * Update the header to point to the new snapshot table. This requires the |
| * new table and its refcounts to be stable on disk. |
| */ |
| ret = bdrv_flush(bs); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| QEMU_BUILD_BUG_ON(offsetof(QCowHeader, snapshots_offset) != |
| offsetof(QCowHeader, nb_snapshots) + sizeof(header_data.nb_snapshots)); |
| |
| header_data.nb_snapshots = cpu_to_be32(s->nb_snapshots); |
| header_data.snapshots_offset = cpu_to_be64(snapshots_offset); |
| |
| ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, nb_snapshots), |
| &header_data, sizeof(header_data)); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| /* free the old snapshot table */ |
| qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size, |
| QCOW2_DISCARD_SNAPSHOT); |
| s->snapshots_offset = snapshots_offset; |
| s->snapshots_size = snapshots_size; |
| return 0; |
| |
| fail: |
| if (snapshots_offset > 0) { |
| qcow2_free_clusters(bs, snapshots_offset, snapshots_size, |
| QCOW2_DISCARD_ALWAYS); |
| } |
| return ret; |
| } |
| |
| static void find_new_snapshot_id(BlockDriverState *bs, |
| char *id_str, int id_str_size) |
| { |
| BDRVQcowState *s = bs->opaque; |
| QCowSnapshot *sn; |
| int i; |
| unsigned long id, id_max = 0; |
| |
| for(i = 0; i < s->nb_snapshots; i++) { |
| sn = s->snapshots + i; |
| id = strtoul(sn->id_str, NULL, 10); |
| if (id > id_max) |
| id_max = id; |
| } |
| snprintf(id_str, id_str_size, "%lu", id_max + 1); |
| } |
| |
| static int find_snapshot_by_id_and_name(BlockDriverState *bs, |
| const char *id, |
| const char *name) |
| { |
| BDRVQcowState *s = bs->opaque; |
| int i; |
| |
| if (id && name) { |
| for (i = 0; i < s->nb_snapshots; i++) { |
| if (!strcmp(s->snapshots[i].id_str, id) && |
| !strcmp(s->snapshots[i].name, name)) { |
| return i; |
| } |
| } |
| } else if (id) { |
| for (i = 0; i < s->nb_snapshots; i++) { |
| if (!strcmp(s->snapshots[i].id_str, id)) { |
| return i; |
| } |
| } |
| } else if (name) { |
| for (i = 0; i < s->nb_snapshots; i++) { |
| if (!strcmp(s->snapshots[i].name, name)) { |
| return i; |
| } |
| } |
| } |
| |
| return -1; |
| } |
| |
| static int find_snapshot_by_id_or_name(BlockDriverState *bs, |
| const char *id_or_name) |
| { |
| int ret; |
| |
| ret = find_snapshot_by_id_and_name(bs, id_or_name, NULL); |
| if (ret >= 0) { |
| return ret; |
| } |
| return find_snapshot_by_id_and_name(bs, NULL, id_or_name); |
| } |
| |
| /* if no id is provided, a new one is constructed */ |
| int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info) |
| { |
| BDRVQcowState *s = bs->opaque; |
| QCowSnapshot *new_snapshot_list = NULL; |
| QCowSnapshot *old_snapshot_list = NULL; |
| QCowSnapshot sn1, *sn = &sn1; |
| int i, ret; |
| uint64_t *l1_table = NULL; |
| int64_t l1_table_offset; |
| |
| if (s->nb_snapshots >= QCOW_MAX_SNAPSHOTS) { |
| return -EFBIG; |
| } |
| |
| memset(sn, 0, sizeof(*sn)); |
| |
| /* Generate an ID */ |
| find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str)); |
| |
| /* Check that the ID is unique */ |
| if (find_snapshot_by_id_and_name(bs, sn_info->id_str, NULL) >= 0) { |
| return -EEXIST; |
| } |
| |
| /* Populate sn with passed data */ |
| sn->id_str = g_strdup(sn_info->id_str); |
| sn->name = g_strdup(sn_info->name); |
| |
| sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE; |
| sn->vm_state_size = sn_info->vm_state_size; |
| sn->date_sec = sn_info->date_sec; |
| sn->date_nsec = sn_info->date_nsec; |
| sn->vm_clock_nsec = sn_info->vm_clock_nsec; |
| |
| /* Allocate the L1 table of the snapshot and copy the current one there. */ |
| l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t)); |
| if (l1_table_offset < 0) { |
| ret = l1_table_offset; |
| goto fail; |
| } |
| |
| sn->l1_table_offset = l1_table_offset; |
| sn->l1_size = s->l1_size; |
| |
| l1_table = g_try_new(uint64_t, s->l1_size); |
| if (s->l1_size && l1_table == NULL) { |
| ret = -ENOMEM; |
| goto fail; |
| } |
| |
| for(i = 0; i < s->l1_size; i++) { |
| l1_table[i] = cpu_to_be64(s->l1_table[i]); |
| } |
| |
| ret = qcow2_pre_write_overlap_check(bs, 0, sn->l1_table_offset, |
| s->l1_size * sizeof(uint64_t)); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| ret = bdrv_pwrite(bs->file, sn->l1_table_offset, l1_table, |
| s->l1_size * sizeof(uint64_t)); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| g_free(l1_table); |
| l1_table = NULL; |
| |
| /* |
| * Increase the refcounts of all clusters and make sure everything is |
| * stable on disk before updating the snapshot table to contain a pointer |
| * to the new L1 table. |
| */ |
| ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| /* Append the new snapshot to the snapshot list */ |
| new_snapshot_list = g_new(QCowSnapshot, s->nb_snapshots + 1); |
| if (s->snapshots) { |
| memcpy(new_snapshot_list, s->snapshots, |
| s->nb_snapshots * sizeof(QCowSnapshot)); |
| old_snapshot_list = s->snapshots; |
| } |
| s->snapshots = new_snapshot_list; |
| s->snapshots[s->nb_snapshots++] = *sn; |
| |
| ret = qcow2_write_snapshots(bs); |
| if (ret < 0) { |
| g_free(s->snapshots); |
| s->snapshots = old_snapshot_list; |
| s->nb_snapshots--; |
| goto fail; |
| } |
| |
| g_free(old_snapshot_list); |
| |
| /* The VM state isn't needed any more in the active L1 table; in fact, it |
| * hurts by causing expensive COW for the next snapshot. */ |
| qcow2_discard_clusters(bs, qcow2_vm_state_offset(s), |
| align_offset(sn->vm_state_size, s->cluster_size) |
| >> BDRV_SECTOR_BITS, |
| QCOW2_DISCARD_NEVER, false); |
| |
| #ifdef DEBUG_ALLOC |
| { |
| BdrvCheckResult result = {0}; |
| qcow2_check_refcounts(bs, &result, 0); |
| } |
| #endif |
| return 0; |
| |
| fail: |
| g_free(sn->id_str); |
| g_free(sn->name); |
| g_free(l1_table); |
| |
| return ret; |
| } |
| |
| /* copy the snapshot 'snapshot_name' into the current disk image */ |
| int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id) |
| { |
| BDRVQcowState *s = bs->opaque; |
| QCowSnapshot *sn; |
| int i, snapshot_index; |
| int cur_l1_bytes, sn_l1_bytes; |
| int ret; |
| uint64_t *sn_l1_table = NULL; |
| |
| /* Search the snapshot */ |
| snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id); |
| if (snapshot_index < 0) { |
| return -ENOENT; |
| } |
| sn = &s->snapshots[snapshot_index]; |
| |
| if (sn->disk_size != bs->total_sectors * BDRV_SECTOR_SIZE) { |
| error_report("qcow2: Loading snapshots with different disk " |
| "size is not implemented"); |
| ret = -ENOTSUP; |
| goto fail; |
| } |
| |
| /* |
| * Make sure that the current L1 table is big enough to contain the whole |
| * L1 table of the snapshot. If the snapshot L1 table is smaller, the |
| * current one must be padded with zeros. |
| */ |
| ret = qcow2_grow_l1_table(bs, sn->l1_size, true); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| cur_l1_bytes = s->l1_size * sizeof(uint64_t); |
| sn_l1_bytes = sn->l1_size * sizeof(uint64_t); |
| |
| /* |
| * Copy the snapshot L1 table to the current L1 table. |
| * |
| * Before overwriting the old current L1 table on disk, make sure to |
| * increase all refcounts for the clusters referenced by the new one. |
| * Decrease the refcount referenced by the old one only when the L1 |
| * table is overwritten. |
| */ |
| sn_l1_table = g_try_malloc0(cur_l1_bytes); |
| if (cur_l1_bytes && sn_l1_table == NULL) { |
| ret = -ENOMEM; |
| goto fail; |
| } |
| |
| ret = bdrv_pread(bs->file, sn->l1_table_offset, sn_l1_table, sn_l1_bytes); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset, |
| sn->l1_size, 1); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1, |
| s->l1_table_offset, cur_l1_bytes); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| ret = bdrv_pwrite_sync(bs->file, s->l1_table_offset, sn_l1_table, |
| cur_l1_bytes); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| /* |
| * Decrease refcount of clusters of current L1 table. |
| * |
| * At this point, the in-memory s->l1_table points to the old L1 table, |
| * whereas on disk we already have the new one. |
| * |
| * qcow2_update_snapshot_refcount special cases the current L1 table to use |
| * the in-memory data instead of really using the offset to load a new one, |
| * which is why this works. |
| */ |
| ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, |
| s->l1_size, -1); |
| |
| /* |
| * Now update the in-memory L1 table to be in sync with the on-disk one. We |
| * need to do this even if updating refcounts failed. |
| */ |
| for(i = 0;i < s->l1_size; i++) { |
| s->l1_table[i] = be64_to_cpu(sn_l1_table[i]); |
| } |
| |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| g_free(sn_l1_table); |
| sn_l1_table = NULL; |
| |
| /* |
| * Update QCOW_OFLAG_COPIED in the active L1 table (it may have changed |
| * when we decreased the refcount of the old snapshot. |
| */ |
| ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0); |
| if (ret < 0) { |
| goto fail; |
| } |
| |
| #ifdef DEBUG_ALLOC |
| { |
| BdrvCheckResult result = {0}; |
| qcow2_check_refcounts(bs, &result, 0); |
| } |
| #endif |
| return 0; |
| |
| fail: |
| g_free(sn_l1_table); |
| return ret; |
| } |
| |
| int qcow2_snapshot_delete(BlockDriverState *bs, |
| const char *snapshot_id, |
| const char *name, |
| Error **errp) |
| { |
| BDRVQcowState *s = bs->opaque; |
| QCowSnapshot sn; |
| int snapshot_index, ret; |
| |
| /* Search the snapshot */ |
| snapshot_index = find_snapshot_by_id_and_name(bs, snapshot_id, name); |
| if (snapshot_index < 0) { |
| error_setg(errp, "Can't find the snapshot"); |
| return -ENOENT; |
| } |
| sn = s->snapshots[snapshot_index]; |
| |
| /* Remove it from the snapshot list */ |
| memmove(s->snapshots + snapshot_index, |
| s->snapshots + snapshot_index + 1, |
| (s->nb_snapshots - snapshot_index - 1) * sizeof(sn)); |
| s->nb_snapshots--; |
| ret = qcow2_write_snapshots(bs); |
| if (ret < 0) { |
| error_setg_errno(errp, -ret, |
| "Failed to remove snapshot from snapshot list"); |
| return ret; |
| } |
| |
| /* |
| * The snapshot is now unused, clean up. If we fail after this point, we |
| * won't recover but just leak clusters. |
| */ |
| g_free(sn.id_str); |
| g_free(sn.name); |
| |
| /* |
| * Now decrease the refcounts of clusters referenced by the snapshot and |
| * free the L1 table. |
| */ |
| ret = qcow2_update_snapshot_refcount(bs, sn.l1_table_offset, |
| sn.l1_size, -1); |
| if (ret < 0) { |
| error_setg_errno(errp, -ret, "Failed to free the cluster and L1 table"); |
| return ret; |
| } |
| qcow2_free_clusters(bs, sn.l1_table_offset, sn.l1_size * sizeof(uint64_t), |
| QCOW2_DISCARD_SNAPSHOT); |
| |
| /* must update the copied flag on the current cluster offsets */ |
| ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0); |
| if (ret < 0) { |
| error_setg_errno(errp, -ret, |
| "Failed to update snapshot status in disk"); |
| return ret; |
| } |
| |
| #ifdef DEBUG_ALLOC |
| { |
| BdrvCheckResult result = {0}; |
| qcow2_check_refcounts(bs, &result, 0); |
| } |
| #endif |
| return 0; |
| } |
| |
| int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab) |
| { |
| BDRVQcowState *s = bs->opaque; |
| QEMUSnapshotInfo *sn_tab, *sn_info; |
| QCowSnapshot *sn; |
| int i; |
| |
| if (!s->nb_snapshots) { |
| *psn_tab = NULL; |
| return s->nb_snapshots; |
| } |
| |
| sn_tab = g_new0(QEMUSnapshotInfo, s->nb_snapshots); |
| for(i = 0; i < s->nb_snapshots; i++) { |
| sn_info = sn_tab + i; |
| sn = s->snapshots + i; |
| pstrcpy(sn_info->id_str, sizeof(sn_info->id_str), |
| sn->id_str); |
| pstrcpy(sn_info->name, sizeof(sn_info->name), |
| sn->name); |
| sn_info->vm_state_size = sn->vm_state_size; |
| sn_info->date_sec = sn->date_sec; |
| sn_info->date_nsec = sn->date_nsec; |
| sn_info->vm_clock_nsec = sn->vm_clock_nsec; |
| } |
| *psn_tab = sn_tab; |
| return s->nb_snapshots; |
| } |
| |
| int qcow2_snapshot_load_tmp(BlockDriverState *bs, |
| const char *snapshot_id, |
| const char *name, |
| Error **errp) |
| { |
| int i, snapshot_index; |
| BDRVQcowState *s = bs->opaque; |
| QCowSnapshot *sn; |
| uint64_t *new_l1_table; |
| int new_l1_bytes; |
| int ret; |
| |
| assert(bs->read_only); |
| |
| /* Search the snapshot */ |
| snapshot_index = find_snapshot_by_id_and_name(bs, snapshot_id, name); |
| if (snapshot_index < 0) { |
| error_setg(errp, |
| "Can't find snapshot"); |
| return -ENOENT; |
| } |
| sn = &s->snapshots[snapshot_index]; |
| |
| /* Allocate and read in the snapshot's L1 table */ |
| if (sn->l1_size > QCOW_MAX_L1_SIZE / sizeof(uint64_t)) { |
| error_setg(errp, "Snapshot L1 table too large"); |
| return -EFBIG; |
| } |
| new_l1_bytes = sn->l1_size * sizeof(uint64_t); |
| new_l1_table = qemu_try_blockalign(bs->file, |
| align_offset(new_l1_bytes, 512)); |
| if (new_l1_table == NULL) { |
| return -ENOMEM; |
| } |
| |
| ret = bdrv_pread(bs->file, sn->l1_table_offset, new_l1_table, new_l1_bytes); |
| if (ret < 0) { |
| error_setg(errp, "Failed to read l1 table for snapshot"); |
| qemu_vfree(new_l1_table); |
| return ret; |
| } |
| |
| /* Switch the L1 table */ |
| qemu_vfree(s->l1_table); |
| |
| s->l1_size = sn->l1_size; |
| s->l1_table_offset = sn->l1_table_offset; |
| s->l1_table = new_l1_table; |
| |
| for(i = 0;i < s->l1_size; i++) { |
| be64_to_cpus(&s->l1_table[i]); |
| } |
| |
| return 0; |
| } |