Re: [Qemu-devel] [PATCH v2 1/9] qapi: Add optional field "name" to block dirty bitmap

["Benoît Canet" <benoit.canet@irqsave.net>]

The Wednesday 12 Mar 2014 à 14:30:56 (+0800), Fam Zheng wrote :
> This field will be set for user created dirty bitmap. Also pass in an
> error pointer to bdrv_create_dirty_bitmap, so when a name is already
> taken on this BDS, it can report an error message. This is not global
> check, two BDSes can have dirty bitmap with a common name.
> 
> Implemented bdrv_find_dirty_bitmap to find a dirty bitmap by name, will
> be used later when other QMP commands want to reference dirty bitmap by
> name.
> 
> Add bdrv_dirty_bitmap_make_anon. This unsets the name of dirty bitmap.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  block-migration.c     |  3 ++-
>  block.c               | 34 +++++++++++++++++++++++++++++++++-
>  block/mirror.c        |  2 +-
>  include/block/block.h |  8 +++++++-
>  qapi-schema.json      |  4 +++-
>  5 files changed, 46 insertions(+), 5 deletions(-)
> 
> diff --git a/block-migration.c b/block-migration.c
> index 897fdba..e6e016a 100644
> --- a/block-migration.c
> +++ b/block-migration.c
> @@ -315,7 +315,8 @@ static void set_dirty_tracking(void)
>      BlkMigDevState *bmds;
>  
>      QSIMPLEQ_FOREACH(bmds, &block_mig_state.bmds_list, entry) {
> -        bmds->dirty_bitmap = bdrv_create_dirty_bitmap(bmds->bs, BLOCK_SIZE);
> +        bmds->dirty_bitmap = bdrv_create_dirty_bitmap(bmds->bs, BLOCK_SIZE,
> +                                                      NULL, NULL);
>      }
>  }
>  
> diff --git a/block.c b/block.c
> index f1ef4b0..ce48fff 100644
> --- a/block.c
> +++ b/block.c
> @@ -52,6 +52,7 @@
>  
>  struct BdrvDirtyBitmap {
>      HBitmap *bitmap;
> +    char *name;

Why not making name a regular char array like bs->device_name or bs->node_name.
Its emptyness could still be tested and it also would remove some memory management
duties.

>      QLIST_ENTRY(BdrvDirtyBitmap) list;
>  };
>  
> @@ -5048,18 +5049,46 @@ bool bdrv_qiov_is_aligned(BlockDriverState *bs, QEMUIOVector *qiov)
>      return true;
>  }
>  
> -BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs, int granularity)
> +BdrvDirtyBitmap *bdrv_find_dirty_bitmap(BlockDriverState *bs,
> +                                        const char *name)
> +{
> +    BdrvDirtyBitmap *bm;
> +    QLIST_FOREACH(bm, &bs->dirty_bitmaps, list) {
> +        if (!strcmp(name, bm->name)) {
> +            return bm;
> +        }
> +    }
> +    return NULL;
> +}
> +
> +void bdrv_dirty_bitmap_make_anon(BlockDriverState *bs, BdrvDirtyBitmap *bitmap)
> +{
> +    g_free(bitmap->name);
> +    bitmap->name = NULL;
> +}
> +
> +BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
> +                                          int granularity,
> +                                          const char *name,
> +                                          Error **errp)
>  {
>      int64_t bitmap_size;
>      BdrvDirtyBitmap *bitmap;
>  
>      assert((granularity & (granularity - 1)) == 0);
>  
> +    if (name && bdrv_find_dirty_bitmap(bs, name)) {
> +        error_setg(errp, "Bitmap already exists: %s", name);
> +        return NULL;
> +    }
>      granularity >>= BDRV_SECTOR_BITS;
>      assert(granularity);
>      bitmap_size = (bdrv_getlength(bs) >> BDRV_SECTOR_BITS);
>      bitmap = g_malloc0(sizeof(BdrvDirtyBitmap));
>      bitmap->bitmap = hbitmap_alloc(bitmap_size, ffs(granularity) - 1);
> +    if (name) {
> +        bitmap->name = g_strdup(name);
> +    }
>      QLIST_INSERT_HEAD(&bs->dirty_bitmaps, bitmap, list);
>      return bitmap;
>  }
> @@ -5071,6 +5100,7 @@ void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap)
>          if (bm == bitmap) {
>              QLIST_REMOVE(bitmap, list);
>              hbitmap_free(bitmap->bitmap);
> +            g_free(bitmap->name);
>              g_free(bitmap);
>              return;
>          }
> @@ -5089,6 +5119,8 @@ BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs)
>          info->count = bdrv_get_dirty_count(bs, bm);
>          info->granularity =
>              ((int64_t) BDRV_SECTOR_SIZE << hbitmap_granularity(bm->bitmap));

> +        info->has_name = bm->name[0] != '\0';
> +        info->name = g_strdup(bm->name);
Could bm->name be == NULl here ?

>          entry->value = info;
>          *plist = entry;
>          plist = &entry->next;
> diff --git a/block/mirror.c b/block/mirror.c
> index dd5ee05..be8b2a1 100644
> --- a/block/mirror.c
> +++ b/block/mirror.c
> @@ -596,7 +596,7 @@ static void mirror_start_job(BlockDriverState *bs, BlockDriverState *target,
>      s->granularity = granularity;
>      s->buf_size = MAX(buf_size, granularity);
>  
> -    s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity);
> +    s->dirty_bitmap = bdrv_create_dirty_bitmap(bs, granularity, NULL, errp);
>      bdrv_set_enable_write_cache(s->target, true);
>      bdrv_set_on_error(s->target, on_target_error, on_target_error);
>      bdrv_iostatus_enable(s->target);
> diff --git a/include/block/block.h b/include/block/block.h
> index 780f48b..aa0c5e4 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -437,7 +437,13 @@ bool bdrv_qiov_is_aligned(BlockDriverState *bs, QEMUIOVector *qiov);
>  
>  struct HBitmapIter;
>  typedef struct BdrvDirtyBitmap BdrvDirtyBitmap;
> -BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs, int granularity);
> +BdrvDirtyBitmap *bdrv_create_dirty_bitmap(BlockDriverState *bs,
> +                                          int granularity,
> +                                          const char *name,
> +                                          Error **errp);

> +BdrvDirtyBitmap *bdrv_find_dirty_bitmap(BlockDriverState *bs,
> +                                        const char *name);
This exactly fit in 80 char so no line split is required.

> +void bdrv_dirty_bitmap_make_anon(BlockDriverState *bs, BdrvDirtyBitmap *bitmap);
>  void bdrv_release_dirty_bitmap(BlockDriverState *bs, BdrvDirtyBitmap *bitmap);
>  BlockDirtyInfoList *bdrv_query_dirty_bitmaps(BlockDriverState *bs);
>  int bdrv_get_dirty(BlockDriverState *bs, BdrvDirtyBitmap *bitmap, int64_t sector);
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 6c381b7..4d5bc13 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -1000,6 +1000,8 @@
>  #
>  # Block dirty bitmap information.
>  #
> +# @name: the name of dirty bitmap (Since 2.1)
# @name: #optional the name of dirty bitmap (Since 2.1)

> +#
>  # @count: number of dirty bytes according to the dirty bitmap
>  #
>  # @granularity: granularity of the dirty bitmap in bytes (since 1.4)
> @@ -1007,7 +1009,7 @@
>  # Since: 1.3
>  ##
>  { 'type': 'BlockDirtyInfo',
> -  'data': {'count': 'int', 'granularity': 'int'} }
> +  'data': {'*name': 'str', 'count': 'int', 'granularity': 'int'} }
>  
>  ##
>  # @BlockInfo:
> -- 
> 1.9.0
> 
>