Re: [PATCH 1/4][RFC] Allow storing arbitrary annotations in qcow2 images

[Anthony Liguori <anthony-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>]

This should go through qemu-devel BTW.  Please submit there and I'll 
provide comments.

Regards,

Anthony Liguori

Jorge Lucángeli Obes wrote:
> This patch adds an extra 'annot' field to qcow2 snapshots, and updates
> serialization functions.
>
> Signed-off-by: Jorge Lucángeli Obes <t4m5yn-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
> diff --git a/qemu/block-qcow2.c b/qemu/block-qcow2.c
> index 0f7a069..361d300 100644
> --- a/qemu/block-qcow2.c
> +++ b/qemu/block-qcow2.c
> @@ -106,6 +106,8 @@ typedef struct QCowSnapshot {
>      uint32_t l1_size;
>      char *id_str;
>      char *name;
> +    char *annot;
> +
>      uint32_t vm_state_size;
>      uint32_t date_sec;
>      uint32_t date_nsec;
> @@ -1370,6 +1372,7 @@ static void qcow_free_snapshots(BlockDriverState *bs)
>      for(i = 0; i < s->nb_snapshots; i++) {
>          qemu_free(s->snapshots[i].name);
>          qemu_free(s->snapshots[i].id_str);
> +        qemu_free(s->snapshots[i].annot);
>      }
>      qemu_free(s->snapshots);
>      s->snapshots = NULL;
> @@ -1401,12 +1404,18 @@ static int qcow_read_snapshots(BlockDriverState *bs)
>          sn->date_sec = be32_to_cpu(h.date_sec);
>          sn->date_nsec = be32_to_cpu(h.date_nsec);
>          sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec);
> -        extra_data_size = be32_to_cpu(h.extra_data_size);
>
> +        extra_data_size = be32_to_cpu(h.extra_data_size);
>          id_str_size = be16_to_cpu(h.id_str_size);
>          name_size = be16_to_cpu(h.name_size);
>
> +        sn->annot = qemu_malloc(extra_data_size + 1);
> +        if (!sn->annot)
> +            goto fail;
> +        if (bdrv_pread(s->hd, offset, sn->annot, extra_data_size) !=
> extra_data_size)
> +            goto fail;
>          offset += extra_data_size;
> +        sn->annot[extra_data_size] = '\0';
>
>          sn->id_str = qemu_malloc(id_str_size + 1);
>          if (!sn->id_str)
> @@ -1439,7 +1448,7 @@ static int qcow_write_snapshots(BlockDriverState *bs)
>      QCowSnapshotHeader h;
>      int i, name_size, id_str_size, snapshots_size;
>      uint64_t data64;
> -    uint32_t data32;
> +    uint32_t data32, extra_data_size;
>      int64_t offset, snapshots_offset;
>
>      /* compute the size of the snapshots */
> @@ -1448,6 +1457,7 @@ static int qcow_write_snapshots(BlockDriverState *bs)
>          sn = s->snapshots + i;
>          offset = align_offset(offset, 8);
>          offset += sizeof(h);
> +        offset += strlen(sn->annot);
>          offset += strlen(sn->id_str);
>          offset += strlen(sn->name);
>      }
> @@ -1455,7 +1465,7 @@ static int qcow_write_snapshots(BlockDriverState *bs)
>
>      snapshots_offset = alloc_clusters(bs, snapshots_size);
>      offset = snapshots_offset;
> -
> +
>      for(i = 0; i < s->nb_snapshots; i++) {
>          sn = s->snapshots + i;
>          memset(&h, 0, sizeof(h));
> @@ -1465,7 +1475,9 @@ static int qcow_write_snapshots(BlockDriverState *bs)
>          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);
> -
> +
> +        extra_data_size = strlen(sn->annot);
> +        h.extra_data_size = cpu_to_be32(extra_data_size);
>          id_str_size = strlen(sn->id_str);
>          name_size = strlen(sn->name);
>          h.id_str_size = cpu_to_be16(id_str_size);
> @@ -1474,6 +1486,9 @@ static int qcow_write_snapshots(BlockDriverState *bs)
>          if (bdrv_pwrite(s->hd, offset, &h, sizeof(h)) != sizeof(h))
>              goto fail;
>          offset += sizeof(h);
> +        if (bdrv_pwrite(s->hd, offset, sn->annot, extra_data_size) !=
> extra_data_size)
> +            goto fail;
> +        offset += extra_data_size;
>          if (bdrv_pwrite(s->hd, offset, sn->id_str, id_str_size) != id_str_size)
>              goto fail;
>          offset += id_str_size;
> @@ -1570,6 +1585,10 @@ static int qcow_snapshot_create(BlockDriverState *bs,
>      sn->name = qemu_strdup(sn_info->name);
>      if (!sn->name)
>          goto fail;
> +    sn->annot = qemu_strdup(sn_info->annot);
> +    if (!sn->annot)
> +        goto fail;
> +
>      sn->vm_state_size = sn_info->vm_state_size;
>      sn->date_sec = sn_info->date_sec;
>      sn->date_nsec = sn_info->date_nsec;
> @@ -1680,6 +1699,8 @@ static int qcow_snapshot_delete(BlockDriverState
> *bs, const char *snapshot_id)
>
>      qemu_free(sn->id_str);
>      qemu_free(sn->name);
> +    qemu_free(sn->annot);
> +
>      memmove(sn, sn + 1, (s->nb_snapshots - snapshot_index - 1) * sizeof(*sn));
>      s->nb_snapshots--;
>      ret = qcow_write_snapshots(bs);
> @@ -1707,10 +1728,14 @@ static int qcow_snapshot_list(BlockDriverState *bs,
>      for(i = 0; i < s->nb_snapshots; i++) {
>          sn_info = sn_tab + i;
>          sn = s->snapshots + i;
> +
>          pstrcpy(sn_info->id_str, sizeof(sn_info->id_str),
>                  sn->id_str);
>          pstrcpy(sn_info->name, sizeof(sn_info->name),
>                  sn->name);
> +        pstrcpy(sn_info->annot, sizeof(sn_info->annot),
> +                sn->annot);
> +
>          sn_info->vm_state_size = sn->vm_state_size;
>          sn_info->date_sec = sn->date_sec;
>          sn_info->date_nsec = sn->date_nsec;
> diff --git a/qemu/vl.h b/qemu/vl.h
> index 43f56bd..f0273fd 100644
> --- a/qemu/vl.h
> +++ b/qemu/vl.h
> @@ -589,6 +589,7 @@ typedef struct QEMUSnapshotInfo {
>      /* the following fields are informative. They are not needed for
>         the consistency of the snapshot */
>      char name[256]; /* user choosen name */
> +    char annot[1024]; /* extra info, will be used to store
> command-line parameters */
>      uint32_t vm_state_size; /* VM state info size */
>      uint32_t date_sec; /* UTC date of the snapshot */
>      uint32_t date_nsec;
> @@ -631,6 +632,7 @@ int bdrv_pread(BlockDriverState *bs, int64_t offset,
>  int bdrv_pwrite(BlockDriverState *bs, int64_t offset,
>                  const void *buf, int count);
>  int bdrv_truncate(BlockDriverState *bs, int64_t offset);
> +
>  int64_t bdrv_getlength(BlockDriverState *bs);
>  void bdrv_get_geometry(BlockDriverState *bs, int64_t *nb_sectors_ptr);
>  int bdrv_commit(BlockDriverState *bs);
> @@ -714,6 +716,12 @@ void path_combine(char *dest, int dest_size,
>                    const char *base_path,
>                    const char *filename);
>
> +/* annotations */
> +int bdrv_snapshot_annotated(QEMUSnapshotInfo *sn_info);
> +int bdrv_set_annot(BlockDriverState *bs, const char *name,
> +                   const char *annotation);
> +char *bdrv_get_annot(BlockDriverState *bs, const char *name);
> +
>  #ifndef QEMU_TOOL
>
>  typedef void QEMUMachineInitFunc(int ram_size, int vga_ram_size,
>   
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