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; memset(sn, 0, sizeof(*sn)); /* Generate an ID if it wasn't passed */ if (sn_info->id_str[0] == '\0') { 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_malloc(s->l1_size * sizeof(uint64_t)); 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, QCOW2_OL_DEFAULT, 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_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot)); 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); #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; }