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.dovga...@ispras.ru> Acked-by: Kevin Wolf <kw...@redhat.com> -- v2: - documented format changes in docs/interop/qcow2.txt (suggested by Eric Blake) v10: - updated the documentation --- block/qcow2-snapshot.c | 7 +++++++ block/qcow2.h | 2 ++ docs/interop/qcow2.txt | 4 ++++ 3 files changed, 13 insertions(+) diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c index a6ffae89a6..52b535425a 100644 --- a/block/qcow2-snapshot.c +++ b/block/qcow2-snapshot.c @@ -103,6 +103,12 @@ int qcow2_read_snapshots(BlockDriverState *bs) sn->disk_size = bs->total_sectors * BDRV_SECTOR_SIZE; } + if (extra_data_size >= 24) { + sn->icount = be64_to_cpu(extra.icount); + } else { + sn->icount = -1ULL; + } + /* Read snapshot ID */ sn->id_str = g_malloc(id_str_size + 1); ret = bdrv_pread(bs->file, offset, sn->id_str, id_str_size); @@ -209,6 +215,7 @@ static 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 fdee297f33..7838dcbcea 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -160,6 +160,7 @@ typedef struct QEMU_PACKED QCowSnapshotHeader { typedef struct QEMU_PACKED QCowSnapshotExtraData { uint64_t vm_state_size_large; uint64_t disk_size; + uint64_t icount; } QCowSnapshotExtraData; @@ -173,6 +174,7 @@ typedef struct QCowSnapshot { uint32_t date_sec; uint32_t date_nsec; uint64_t vm_clock_nsec; + uint64_t icount; } QCowSnapshot; struct Qcow2Cache; diff --git a/docs/interop/qcow2.txt b/docs/interop/qcow2.txt index af5711e533..aa9d447cda 100644 --- a/docs/interop/qcow2.txt +++ b/docs/interop/qcow2.txt @@ -584,6 +584,10 @@ 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 + Version 3 images must include extra data at least up to byte 55.