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qcow2: Allow >4 GB VM state

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This is a compatible extension to the snapshot header format that allows
saving a 64 bit VM state size.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Kevin Wolf 2011-11-16 11:35:54 +01:00
parent 3763f26f2f
commit c2c9a46609
5 changed files with 42 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

34
block/qcow2-snapshot.c
View file

@ -46,6 +46,10 @@ typedef struct QEMU_PACKED QCowSnapshotHeader {
/* name follows */
} QCowSnapshotHeader;
typedef struct QEMU_PACKED QCowSnapshotExtraData {
uint64_t vm_state_size_large;
} QCowSnapshotExtraData;
void qcow2_free_snapshots(BlockDriverState *bs)
{
BDRVQcowState *s = bs->opaque;
@ -64,6 +68,7 @@ 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;
@ -100,9 +105,18 @@ int qcow2_read_snapshots(BlockDriverState *bs)
id_str_size = be16_to_cpu(h.id_str_size);
name_size = be16_to_cpu(h.name_size);
/* Skip extra data */
/* 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);
}
/* Read snapshot ID */
sn->id_str = g_malloc(id_str_size + 1);
ret = bdrv_pread(bs->file, offset, sn->id_str, id_str_size);
@ -136,6 +150,7 @@ 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;
@ -150,6 +165,7 @@ static int qcow2_write_snapshots(BlockDriverState *bs)
sn = s->snapshots + i;
offset = align_offset(offset, 8);
offset += sizeof(h);
offset += sizeof(extra);
offset += strlen(sn->id_str);
offset += strlen(sn->name);
}
@ -169,10 +185,18 @@ static int qcow2_write_snapshots(BlockDriverState *bs)
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);
/* 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);
id_str_size = strlen(sn->id_str);
name_size = strlen(sn->name);
@ -186,6 +210,12 @@ static int qcow2_write_snapshots(BlockDriverState *bs)
}
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;