qemu/block/qcow2-snapshot.c
Kevin Wolf 66f82ceed6 block: Open the underlying image file in generic code
Format drivers shouldn't need to bother with things like file names, but rather
just get an open BlockDriverState for the underlying protocol. This patch
introduces this behaviour for bdrv_open implementation. For protocols which
need to access the filename to open their file/device/connection/... a new
callback bdrv_file_open is introduced which doesn't get an underlying file
opened.

For now, also some of the more obscure formats use bdrv_file_open because they
open() the file themselves instead of using the block.c functions. They need to
be fixed in later patches.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
2010-05-03 10:07:30 +02:00

420 lines
12 KiB
C

/*
* 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(bs->file, 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(bs->file, 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(bs->file, 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(bs->file, offset, &h, sizeof(h)) != sizeof(h))
goto fail;
offset += sizeof(h);
if (bdrv_pwrite(bs->file, offset, sn->id_str, id_str_size) != id_str_size)
goto fail;
offset += id_str_size;
if (bdrv_pwrite(bs->file, 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(bs->file, offsetof(QCowHeader, snapshots_offset),
&data64, sizeof(data64)) != sizeof(data64))
goto fail;
data32 = cpu_to_be32(s->nb_snapshots);
if (bdrv_pwrite(bs->file, 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(bs->file, 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(bs->file, sn->l1_table_offset,
s->l1_table, l1_size2) != l1_size2)
goto fail;
if (bdrv_pwrite(bs->file, 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;
}