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authorKevin Wolf <kwolf@redhat.com>2011-11-16 11:35:54 +0100
committerKevin Wolf <kwolf@redhat.com>2011-12-15 12:40:33 +0100
commitc2c9a46609164a36b477f6cff1d10ed27a6b53fc (patch)
tree7cf3cf48bcc3e87a93457b5bb5ef9a7cc468ca2e /block/qcow2-snapshot.c
parent3763f26f2fdff156fec6868b651fe7853fc64de5 (diff)
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qcow2: Allow >4 GB VM state
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>
Diffstat (limited to 'block/qcow2-snapshot.c')
-rw-r--r--block/qcow2-snapshot.c34
1 files changed, 32 insertions, 2 deletions
diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index c3112bf..7d3fde5 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -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;