From: Pavel Dovgalyuk <pavel.dovga...@ispras.ru>
This patch introduces the icount field for saving within the snapshot.
It is required for navigation between the snapshots in record/replay mode.
Signed-off-by: Pavel Dovgalyuk <pavel.dovgal...@ispras.ru>
Acked-by: Kevin Wolf <kw...@redhat.com>
---
0 files changed
diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index 2756b37d24..d14e7be1aa 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -164,6 +164,12 @@ static int qcow2_do_read_snapshots(BlockDriverState *bs,
bool repair,
sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE;
}
+ if (sn->extra_data_size >= endof(QCowSnapshotExtraData, icount)) {
+ sn->icount = be64_to_cpu(extra.icount);
+ } else {
+ sn->icount = -1ULL;
+ }
+
if (sn->extra_data_size > sizeof(extra)) {
uint64_t extra_data_end;
size_t unknown_extra_data_size;
@@ -333,6 +339,7 @@ int qcow2_write_snapshots(BlockDriverState *bs)
memset(&extra, 0, sizeof(extra));
extra.vm_state_size_large = cpu_to_be64(sn->vm_state_size);
extra.disk_size = cpu_to_be64(sn->disk_size);
+ extra.icount = cpu_to_be64(sn->icount);
id_str_size = strlen(sn->id_str);
name_size = strlen(sn->name);
diff --git a/block/qcow2.h b/block/qcow2.h
index 7ce2c23bdb..9c81086991 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -179,6 +179,7 @@ typedef struct QEMU_PACKED QCowSnapshotHeader {
typedef struct QEMU_PACKED QCowSnapshotExtraData {
uint64_t vm_state_size_large;
uint64_t disk_size;
+ uint64_t icount;
} QCowSnapshotExtraData;
@@ -192,6 +193,8 @@ typedef struct QCowSnapshot {
uint32_t date_sec;
uint32_t date_nsec;
uint64_t vm_clock_nsec;
+ /* icount value for the moment when snapshot was taken */
+ uint64_t icount;
/* Size of all extra data, including QCowSnapshotExtraData if available */
uint32_t extra_data_size;
/* Data beyond QCowSnapshotExtraData, if any */
diff --git a/docs/interop/qcow2.txt b/docs/interop/qcow2.txt
index cb723463f2..06014c0e90 100644
--- a/docs/interop/qcow2.txt
+++ b/docs/interop/qcow2.txt
@@ -645,6 +645,11 @@ Snapshot table entry:
Byte 48 - 55: Virtual disk size of the snapshot in bytes
+ Byte 56 - 63: icount value which corresponds to
+ the record/replay instruction count
+ when the snapshot was taken. Set to -1
+ if icount was disabled
+
Version 3 images must include extra data at least up to
byte 55.
