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

[Fam Zheng <famz@redhat.com>]

On Thu, 03/13 14:15, Benoît Canet wrote:
> 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.

Version 1 did use an array. This is Stefan's request.

> 
> >      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 ?

It doesn't matter. g_strdup returns NULL for NULL.

> 
> >          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.

OK.

> 
> > +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)

OK.

Thanks,
Fam