[Qemu-devel] [RFC PATCH 07/17] qcow2: introduce icount field for snapshots

[Pavel Dovgalyuk <Pavel.Dovgaluk@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.Dovgaluk@ispras.ru>
---
 block/qcow2-snapshot.c |    9 +++++++++
 block/qcow2.h          |    2 ++
 2 files changed, 11 insertions(+)

diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index 74293be..4f2357e 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 = 0;
+        }
+
         /* 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);
@@ -372,6 +379,7 @@ int qcow2_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info)
     sn->date_sec = sn_info->date_sec;
     sn->date_nsec = sn_info->date_nsec;
     sn->vm_clock_nsec = sn_info->vm_clock_nsec;
+    sn->icount = sn_info->icount;
 
     /* Allocate the L1 table of the snapshot and copy the current one there. */
     l1_table_offset = qcow2_alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
@@ -691,6 +699,7 @@ int qcow2_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab)
         sn_info->date_sec = sn->date_sec;
         sn_info->date_nsec = sn->date_nsec;
         sn_info->vm_clock_nsec = sn->vm_clock_nsec;
+        sn_info->icount = sn->icount;
     }
     *psn_tab = sn_tab;
     return s->nb_snapshots;
diff --git a/block/qcow2.h b/block/qcow2.h
index adf5c39..8880937 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -151,6 +151,7 @@ typedef struct QEMU_PACKED QCowSnapshotHeader {
 typedef struct QEMU_PACKED QCowSnapshotExtraData {
     uint64_t vm_state_size_large;
     uint64_t disk_size;
+    uint64_t icount;
 } QCowSnapshotExtraData;
 
 
@@ -164,6 +165,7 @@ typedef struct QCowSnapshot {
     uint32_t date_sec;
     uint32_t date_nsec;
     uint64_t vm_clock_nsec;
+    uint64_t icount;
 } QCowSnapshot;
 
 struct Qcow2Cache;