683 lines
19 KiB
C
683 lines
19 KiB
C
/*
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* Block driver for the QCOW version 2 format
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*
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* Copyright (c) 2004-2006 Fabrice Bellard
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include "qemu-common.h"
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#include "block/block_int.h"
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#include "block/qcow2.h"
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typedef struct QEMU_PACKED QCowSnapshotHeader {
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/* header is 8 byte aligned */
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uint64_t l1_table_offset;
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uint32_t l1_size;
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uint16_t id_str_size;
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uint16_t name_size;
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uint32_t date_sec;
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uint32_t date_nsec;
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uint64_t vm_clock_nsec;
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uint32_t vm_state_size;
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uint32_t extra_data_size; /* for extension */
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/* extra data follows */
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/* id_str follows */
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/* name follows */
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} QCowSnapshotHeader;
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typedef struct QEMU_PACKED QCowSnapshotExtraData {
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uint64_t vm_state_size_large;
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uint64_t disk_size;
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} QCowSnapshotExtraData;
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void qcow2_free_snapshots(BlockDriverState *bs)
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{
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BDRVQcowState *s = bs->opaque;
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int i;
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for(i = 0; i < s->nb_snapshots; i++) {
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g_free(s->snapshots[i].name);
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g_free(s->snapshots[i].id_str);
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}
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g_free(s->snapshots);
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s->snapshots = NULL;
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s->nb_snapshots = 0;
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}
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int qcow2_read_snapshots(BlockDriverState *bs)
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{
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BDRVQcowState *s = bs->opaque;
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QCowSnapshotHeader h;
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QCowSnapshotExtraData extra;
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QCowSnapshot *sn;
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int i, id_str_size, name_size;
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int64_t offset;
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uint32_t extra_data_size;
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int ret;
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if (!s->nb_snapshots) {
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s->snapshots = NULL;
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s->snapshots_size = 0;
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return 0;
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}
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offset = s->snapshots_offset;
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s->snapshots = g_malloc0(s->nb_snapshots * sizeof(QCowSnapshot));
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for(i = 0; i < s->nb_snapshots; i++) {
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/* Read statically sized part of the snapshot header */
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offset = align_offset(offset, 8);
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ret = bdrv_pread(bs->file, offset, &h, sizeof(h));
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if (ret < 0) {
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goto fail;
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}
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offset += sizeof(h);
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sn = s->snapshots + i;
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sn->l1_table_offset = be64_to_cpu(h.l1_table_offset);
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sn->l1_size = be32_to_cpu(h.l1_size);
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sn->vm_state_size = be32_to_cpu(h.vm_state_size);
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sn->date_sec = be32_to_cpu(h.date_sec);
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sn->date_nsec = be32_to_cpu(h.date_nsec);
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sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec);
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extra_data_size = be32_to_cpu(h.extra_data_size);
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id_str_size = be16_to_cpu(h.id_str_size);
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name_size = be16_to_cpu(h.name_size);
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/* Read extra data */
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ret = bdrv_pread(bs->file, offset, &extra,
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MIN(sizeof(extra), extra_data_size));
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if (ret < 0) {
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goto fail;
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}
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offset += extra_data_size;
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if (extra_data_size >= 8) {
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sn->vm_state_size = be64_to_cpu(extra.vm_state_size_large);
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}
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if (extra_data_size >= 16) {
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sn->disk_size = be64_to_cpu(extra.disk_size);
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} else {
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sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
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}
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/* Read snapshot ID */
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sn->id_str = g_malloc(id_str_size + 1);
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ret = bdrv_pread(bs->file, offset, sn->id_str, id_str_size);
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if (ret < 0) {
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goto fail;
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}
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offset += id_str_size;
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sn->id_str[id_str_size] = '\0';
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/* Read snapshot name */
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sn->name = g_malloc(name_size + 1);
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ret = bdrv_pread(bs->file, offset, sn->name, name_size);
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if (ret < 0) {
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goto fail;
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}
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offset += name_size;
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sn->name[name_size] = '\0';
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}
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s->snapshots_size = offset - s->snapshots_offset;
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return 0;
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fail:
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qcow2_free_snapshots(bs);
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return ret;
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}
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/* add at the end of the file a new list of snapshots */
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static int qcow2_write_snapshots(BlockDriverState *bs)
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{
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BDRVQcowState *s = bs->opaque;
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QCowSnapshot *sn;
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QCowSnapshotHeader h;
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QCowSnapshotExtraData extra;
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int i, name_size, id_str_size, snapshots_size;
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struct {
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uint32_t nb_snapshots;
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uint64_t snapshots_offset;
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} QEMU_PACKED header_data;
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int64_t offset, snapshots_offset;
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int ret;
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/* compute the size of the snapshots */
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offset = 0;
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for(i = 0; i < s->nb_snapshots; i++) {
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sn = s->snapshots + i;
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offset = align_offset(offset, 8);
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offset += sizeof(h);
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offset += sizeof(extra);
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offset += strlen(sn->id_str);
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offset += strlen(sn->name);
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}
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snapshots_size = offset;
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/* Allocate space for the new snapshot list */
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snapshots_offset = qcow2_alloc_clusters(bs, snapshots_size);
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offset = snapshots_offset;
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if (offset < 0) {
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return offset;
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}
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ret = bdrv_flush(bs);
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if (ret < 0) {
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return ret;
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}
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/* The snapshot list position has not yet been updated, so these clusters
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* must indeed be completely free */
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ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT, offset,
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s->snapshots_size);
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if (ret < 0) {
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return ret;
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}
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/* Write all snapshots to the new list */
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for(i = 0; i < s->nb_snapshots; i++) {
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sn = s->snapshots + i;
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memset(&h, 0, sizeof(h));
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h.l1_table_offset = cpu_to_be64(sn->l1_table_offset);
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h.l1_size = cpu_to_be32(sn->l1_size);
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/* If it doesn't fit in 32 bit, older implementations should treat it
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* as a disk-only snapshot rather than truncate the VM state */
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if (sn->vm_state_size <= 0xffffffff) {
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h.vm_state_size = cpu_to_be32(sn->vm_state_size);
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}
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h.date_sec = cpu_to_be32(sn->date_sec);
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h.date_nsec = cpu_to_be32(sn->date_nsec);
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h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec);
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h.extra_data_size = cpu_to_be32(sizeof(extra));
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memset(&extra, 0, sizeof(extra));
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extra.vm_state_size_large = cpu_to_be64(sn->vm_state_size);
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extra.disk_size = cpu_to_be64(sn->disk_size);
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id_str_size = strlen(sn->id_str);
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name_size = strlen(sn->name);
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h.id_str_size = cpu_to_be16(id_str_size);
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h.name_size = cpu_to_be16(name_size);
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offset = align_offset(offset, 8);
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ret = bdrv_pwrite(bs->file, offset, &h, sizeof(h));
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if (ret < 0) {
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goto fail;
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}
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offset += sizeof(h);
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ret = bdrv_pwrite(bs->file, offset, &extra, sizeof(extra));
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if (ret < 0) {
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goto fail;
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}
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offset += sizeof(extra);
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ret = bdrv_pwrite(bs->file, offset, sn->id_str, id_str_size);
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if (ret < 0) {
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goto fail;
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}
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offset += id_str_size;
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ret = bdrv_pwrite(bs->file, offset, sn->name, name_size);
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if (ret < 0) {
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goto fail;
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}
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offset += name_size;
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}
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/*
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* Update the header to point to the new snapshot table. This requires the
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* new table and its refcounts to be stable on disk.
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*/
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ret = bdrv_flush(bs);
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if (ret < 0) {
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goto fail;
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}
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QEMU_BUILD_BUG_ON(offsetof(QCowHeader, snapshots_offset) !=
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offsetof(QCowHeader, nb_snapshots) + sizeof(header_data.nb_snapshots));
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header_data.nb_snapshots = cpu_to_be32(s->nb_snapshots);
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header_data.snapshots_offset = cpu_to_be64(snapshots_offset);
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ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, nb_snapshots),
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&header_data, sizeof(header_data));
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if (ret < 0) {
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goto fail;
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}
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/* free the old snapshot table */
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qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size,
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QCOW2_DISCARD_SNAPSHOT);
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s->snapshots_offset = snapshots_offset;
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s->snapshots_size = snapshots_size;
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return 0;
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fail:
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return ret;
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}
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static void find_new_snapshot_id(BlockDriverState *bs,
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char *id_str, int id_str_size)
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{
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BDRVQcowState *s = bs->opaque;
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QCowSnapshot *sn;
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int i, id, id_max = 0;
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for(i = 0; i < s->nb_snapshots; i++) {
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sn = s->snapshots + i;
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id = strtoul(sn->id_str, NULL, 10);
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if (id > id_max)
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id_max = id;
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}
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snprintf(id_str, id_str_size, "%d", id_max + 1);
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}
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static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str)
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{
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BDRVQcowState *s = bs->opaque;
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int i;
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for(i = 0; i < s->nb_snapshots; i++) {
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if (!strcmp(s->snapshots[i].id_str, id_str))
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return i;
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}
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return -1;
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}
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static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name)
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{
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BDRVQcowState *s = bs->opaque;
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int i, ret;
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ret = find_snapshot_by_id(bs, name);
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if (ret >= 0)
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return ret;
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for(i = 0; i < s->nb_snapshots; i++) {
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if (!strcmp(s->snapshots[i].name, name))
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return i;
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}
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return -1;
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}
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/* if no id is provided, a new one is constructed */
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int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
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{
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BDRVQcowState *s = bs->opaque;
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QCowSnapshot *new_snapshot_list = NULL;
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QCowSnapshot *old_snapshot_list = NULL;
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QCowSnapshot sn1, *sn = &sn1;
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int i, ret;
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uint64_t *l1_table = NULL;
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int64_t l1_table_offset;
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memset(sn, 0, sizeof(*sn));
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/* Generate an ID if it wasn't passed */
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if (sn_info->id_str[0] == '\0') {
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find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str));
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}
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/* Check that the ID is unique */
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if (find_snapshot_by_id(bs, sn_info->id_str) >= 0) {
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return -EEXIST;
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}
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/* Populate sn with passed data */
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sn->id_str = g_strdup(sn_info->id_str);
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sn->name = g_strdup(sn_info->name);
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sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
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sn->vm_state_size = sn_info->vm_state_size;
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sn->date_sec = sn_info->date_sec;
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sn->date_nsec = sn_info->date_nsec;
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sn->vm_clock_nsec = sn_info->vm_clock_nsec;
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/* Allocate the L1 table of the snapshot and copy the current one there. */
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l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
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if (l1_table_offset < 0) {
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ret = l1_table_offset;
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goto fail;
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}
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sn->l1_table_offset = l1_table_offset;
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sn->l1_size = s->l1_size;
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l1_table = g_malloc(s->l1_size * sizeof(uint64_t));
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for(i = 0; i < s->l1_size; i++) {
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l1_table[i] = cpu_to_be64(s->l1_table[i]);
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}
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ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_DEFAULT,
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sn->l1_table_offset, s->l1_size * sizeof(uint64_t));
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if (ret < 0) {
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goto fail;
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}
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ret = bdrv_pwrite(bs->file, sn->l1_table_offset, l1_table,
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s->l1_size * sizeof(uint64_t));
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if (ret < 0) {
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goto fail;
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}
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g_free(l1_table);
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l1_table = NULL;
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/*
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* Increase the refcounts of all clusters and make sure everything is
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* stable on disk before updating the snapshot table to contain a pointer
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* to the new L1 table.
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*/
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ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
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if (ret < 0) {
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goto fail;
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}
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/* Append the new snapshot to the snapshot list */
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new_snapshot_list = g_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
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if (s->snapshots) {
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memcpy(new_snapshot_list, s->snapshots,
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s->nb_snapshots * sizeof(QCowSnapshot));
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old_snapshot_list = s->snapshots;
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}
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s->snapshots = new_snapshot_list;
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s->snapshots[s->nb_snapshots++] = *sn;
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ret = qcow2_write_snapshots(bs);
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if (ret < 0) {
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g_free(s->snapshots);
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s->snapshots = old_snapshot_list;
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goto fail;
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}
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g_free(old_snapshot_list);
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#ifdef DEBUG_ALLOC
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{
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BdrvCheckResult result = {0};
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qcow2_check_refcounts(bs, &result, 0);
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}
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#endif
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return 0;
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fail:
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g_free(sn->id_str);
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g_free(sn->name);
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g_free(l1_table);
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return ret;
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}
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/* copy the snapshot 'snapshot_name' into the current disk image */
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int qcow2_snapshot_goto(BlockDriverState *bs, const char *snapshot_id)
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{
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BDRVQcowState *s = bs->opaque;
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QCowSnapshot *sn;
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int i, snapshot_index;
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int cur_l1_bytes, sn_l1_bytes;
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int ret;
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uint64_t *sn_l1_table = NULL;
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/* Search the snapshot */
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snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
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if (snapshot_index < 0) {
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return -ENOENT;
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}
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sn = &s->snapshots[snapshot_index];
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if (sn->disk_size != bs->total_sectors * BDRV_SECTOR_SIZE) {
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error_report("qcow2: Loading snapshots with different disk "
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"size is not implemented");
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ret = -ENOTSUP;
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goto fail;
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}
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/*
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* Make sure that the current L1 table is big enough to contain the whole
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* L1 table of the snapshot. If the snapshot L1 table is smaller, the
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* current one must be padded with zeros.
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*/
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ret = qcow2_grow_l1_table(bs, sn->l1_size, true);
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if (ret < 0) {
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goto fail;
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}
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cur_l1_bytes = s->l1_size * sizeof(uint64_t);
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sn_l1_bytes = sn->l1_size * sizeof(uint64_t);
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/*
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* Copy the snapshot L1 table to the current L1 table.
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*
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* Before overwriting the old current L1 table on disk, make sure to
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* increase all refcounts for the clusters referenced by the new one.
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* Decrease the refcount referenced by the old one only when the L1
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* table is overwritten.
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*/
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sn_l1_table = g_malloc0(cur_l1_bytes);
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ret = bdrv_pread(bs->file, sn->l1_table_offset, sn_l1_table, sn_l1_bytes);
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if (ret < 0) {
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goto fail;
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}
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ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset,
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sn->l1_size, 1);
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if (ret < 0) {
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goto fail;
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}
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ret = qcow2_pre_write_overlap_check(bs,
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QCOW2_OL_DEFAULT & ~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)
|
|
{
|
|
BDRVQcowState *s = bs->opaque;
|
|
QCowSnapshot sn;
|
|
int snapshot_index, ret;
|
|
|
|
/* 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];
|
|
|
|
/* 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) {
|
|
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) {
|
|
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) {
|
|
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_malloc0(s->nb_snapshots * sizeof(QEMUSnapshotInfo));
|
|
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_name)
|
|
{
|
|
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_or_name(bs, snapshot_name);
|
|
if (snapshot_index < 0) {
|
|
return -ENOENT;
|
|
}
|
|
sn = &s->snapshots[snapshot_index];
|
|
|
|
/* Allocate and read in the snapshot's L1 table */
|
|
new_l1_bytes = s->l1_size * sizeof(uint64_t);
|
|
new_l1_table = g_malloc0(align_offset(new_l1_bytes, 512));
|
|
|
|
ret = bdrv_pread(bs->file, sn->l1_table_offset, new_l1_table, new_l1_bytes);
|
|
if (ret < 0) {
|
|
g_free(new_l1_table);
|
|
return ret;
|
|
}
|
|
|
|
/* Switch the L1 table */
|
|
g_free(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;
|
|
}
|