qemu-e2k/block/qcow2-snapshot.c

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/*
* 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_int.h"
#include "block/qcow2.h"
typedef struct __attribute__((packed)) QCowSnapshotHeader {
/* header is 8 byte aligned */
uint64_t l1_table_offset;
uint32_t l1_size;
uint16_t id_str_size;
uint16_t name_size;
uint32_t date_sec;
uint32_t date_nsec;
uint64_t vm_clock_nsec;
uint32_t vm_state_size;
uint32_t extra_data_size; /* for extension */
/* extra data follows */
/* id_str follows */
/* name follows */
} QCowSnapshotHeader;
void qcow2_free_snapshots(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
int i;
for(i = 0; i < s->nb_snapshots; i++) {
qemu_free(s->snapshots[i].name);
qemu_free(s->snapshots[i].id_str);
}
qemu_free(s->snapshots);
s->snapshots = NULL;
s->nb_snapshots = 0;
}
int qcow2_read_snapshots(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
QCowSnapshotHeader h;
QCowSnapshot *sn;
int i, id_str_size, name_size;
int64_t offset;
uint32_t extra_data_size;
if (!s->nb_snapshots) {
s->snapshots = NULL;
s->snapshots_size = 0;
return 0;
}
offset = s->snapshots_offset;
s->snapshots = qemu_mallocz(s->nb_snapshots * sizeof(QCowSnapshot));
for(i = 0; i < s->nb_snapshots; i++) {
offset = align_offset(offset, 8);
if (bdrv_pread(s->hd, offset, &h, sizeof(h)) != sizeof(h))
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);
offset += extra_data_size;
sn->id_str = qemu_malloc(id_str_size + 1);
if (bdrv_pread(s->hd, offset, sn->id_str, id_str_size) != id_str_size)
goto fail;
offset += id_str_size;
sn->id_str[id_str_size] = '\0';
sn->name = qemu_malloc(name_size + 1);
if (bdrv_pread(s->hd, offset, sn->name, name_size) != name_size)
goto fail;
offset += name_size;
sn->name[name_size] = '\0';
}
s->snapshots_size = offset - s->snapshots_offset;
return 0;
fail:
qcow2_free_snapshots(bs);
return -1;
}
/* add at the end of the file a new list of snapshots */
static int qcow_write_snapshots(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
QCowSnapshotHeader h;
int i, name_size, id_str_size, snapshots_size;
uint64_t data64;
uint32_t data32;
int64_t offset, snapshots_offset;
/* 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 += strlen(sn->id_str);
offset += strlen(sn->name);
}
snapshots_size = offset;
snapshots_offset = qcow2_alloc_clusters(bs, snapshots_size);
offset = snapshots_offset;
if (offset < 0) {
return offset;
}
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);
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);
id_str_size = strlen(sn->id_str);
name_size = strlen(sn->name);
h.id_str_size = cpu_to_be16(id_str_size);
h.name_size = cpu_to_be16(name_size);
offset = align_offset(offset, 8);
if (bdrv_pwrite(s->hd, offset, &h, sizeof(h)) != sizeof(h))
goto fail;
offset += sizeof(h);
if (bdrv_pwrite(s->hd, offset, sn->id_str, id_str_size) != id_str_size)
goto fail;
offset += id_str_size;
if (bdrv_pwrite(s->hd, offset, sn->name, name_size) != name_size)
goto fail;
offset += name_size;
}
/* update the various header fields */
data64 = cpu_to_be64(snapshots_offset);
if (bdrv_pwrite(s->hd, offsetof(QCowHeader, snapshots_offset),
&data64, sizeof(data64)) != sizeof(data64))
goto fail;
data32 = cpu_to_be32(s->nb_snapshots);
if (bdrv_pwrite(s->hd, offsetof(QCowHeader, nb_snapshots),
&data32, sizeof(data32)) != sizeof(data32))
goto fail;
/* free the old snapshot table */
qcow2_free_clusters(bs, s->snapshots_offset, s->snapshots_size);
s->snapshots_offset = snapshots_offset;
s->snapshots_size = snapshots_size;
return 0;
fail:
return -1;
}
static void find_new_snapshot_id(BlockDriverState *bs,
char *id_str, int id_str_size)
{
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
int i, 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, "%d", id_max + 1);
}
static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str)
{
BDRVQcowState *s = bs->opaque;
int i;
for(i = 0; i < s->nb_snapshots; i++) {
if (!strcmp(s->snapshots[i].id_str, id_str))
return i;
}
return -1;
}
static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name)
{
BDRVQcowState *s = bs->opaque;
int i, ret;
ret = find_snapshot_by_id(bs, name);
if (ret >= 0)
return ret;
for(i = 0; i < s->nb_snapshots; i++) {
if (!strcmp(s->snapshots[i].name, name))
return i;
}
return -1;
}
/* if no id is provided, a new one is constructed */
int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
{
BDRVQcowState *s = bs->opaque;
QCowSnapshot *snapshots1, sn1, *sn = &sn1;
int i, ret;
uint64_t *l1_table = NULL;
int64_t l1_table_offset;
memset(sn, 0, sizeof(*sn));
if (sn_info->id_str[0] == '\0') {
/* compute a new 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(bs, sn_info->id_str) >= 0)
return -ENOENT;
sn->id_str = qemu_strdup(sn_info->id_str);
if (!sn->id_str)
goto fail;
sn->name = qemu_strdup(sn_info->name);
if (!sn->name)
goto fail;
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;
ret = qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
if (ret < 0)
goto fail;
/* create the L1 table of the snapshot */
l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
if (l1_table_offset < 0) {
goto fail;
}
sn->l1_table_offset = l1_table_offset;
sn->l1_size = s->l1_size;
if (s->l1_size != 0) {
l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
} else {
l1_table = NULL;
}
for(i = 0; i < s->l1_size; i++) {
l1_table[i] = cpu_to_be64(s->l1_table[i]);
}
if (bdrv_pwrite(s->hd, sn->l1_table_offset,
l1_table, s->l1_size * sizeof(uint64_t)) !=
(s->l1_size * sizeof(uint64_t)))
goto fail;
qemu_free(l1_table);
l1_table = NULL;
snapshots1 = qemu_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
if (s->snapshots) {
memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot));
qemu_free(s->snapshots);
}
s->snapshots = snapshots1;
s->snapshots[s->nb_snapshots++] = *sn;
if (qcow_write_snapshots(bs) < 0)
goto fail;
#ifdef DEBUG_ALLOC
qcow2_check_refcounts(bs);
#endif
return 0;
fail:
qemu_free(sn->name);
qemu_free(l1_table);
return -1;
}
/* 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, l1_size2;
snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
if (snapshot_index < 0)
return -ENOENT;
sn = &s->snapshots[snapshot_index];
if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1) < 0)
goto fail;
if (qcow2_grow_l1_table(bs, sn->l1_size) < 0)
goto fail;
s->l1_size = sn->l1_size;
l1_size2 = s->l1_size * sizeof(uint64_t);
/* copy the snapshot l1 table to the current l1 table */
if (bdrv_pread(s->hd, sn->l1_table_offset,
s->l1_table, l1_size2) != l1_size2)
goto fail;
if (bdrv_pwrite(s->hd, s->l1_table_offset,
s->l1_table, l1_size2) != l1_size2)
goto fail;
for(i = 0;i < s->l1_size; i++) {
be64_to_cpus(&s->l1_table[i]);
}
if (qcow2_update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1) < 0)
goto fail;
#ifdef DEBUG_ALLOC
qcow2_check_refcounts(bs);
#endif
return 0;
fail:
return -EIO;
}
int qcow2_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
{
BDRVQcowState *s = bs->opaque;
QCowSnapshot *sn;
int snapshot_index, ret;
snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
if (snapshot_index < 0)
return -ENOENT;
sn = &s->snapshots[snapshot_index];
ret = qcow2_update_snapshot_refcount(bs, sn->l1_table_offset, sn->l1_size, -1);
if (ret < 0)
return ret;
/* 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;
qcow2_free_clusters(bs, sn->l1_table_offset, sn->l1_size * sizeof(uint64_t));
qemu_free(sn->id_str);
qemu_free(sn->name);
memmove(sn, sn + 1, (s->nb_snapshots - snapshot_index - 1) * sizeof(*sn));
s->nb_snapshots--;
ret = qcow_write_snapshots(bs);
if (ret < 0) {
/* XXX: restore snapshot if error ? */
return ret;
}
#ifdef DEBUG_ALLOC
qcow2_check_refcounts(bs);
#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 = qemu_mallocz(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;
}