block: Fix bdrv_is_allocated() for short backing files

bdrv_is_allocated() shouldn't return true for sectors that are
unallocated, but after the end of a short backing file, even though
such sectors are (correctly) marked as containing zeros.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block.c               |  8 +++++---
 include/block/block.h | 11 +++++++----
 2 files changed, 12 insertions(+), 7 deletions(-)

Il 06/05/2014 15:30, Kevin Wolf ha scritto:
> bdrv_is_allocated() shouldn't return true for sectors that are
> unallocated, but after the end of a short backing file, even though
> such sectors are (correctly) marked as containing zeros.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Nice. :)

Paolo

On 06.05.2014 15:30, Kevin Wolf wrote:
> bdrv_is_allocated() shouldn't return true for sectors that are
> unallocated, but after the end of a short backing file, even though
> such sectors are (correctly) marked as containing zeros.
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   block.c               |  8 +++++---
>   include/block/block.h | 11 +++++++----
>   2 files changed, 12 insertions(+), 7 deletions(-)
>
> diff --git a/block.c b/block.c
> index c90c71a..d3a9906 100644
> --- a/block.c
> +++ b/block.c
> @@ -3883,6 +3883,10 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
>                                        *pnum, pnum);
>       }
>   
> +    if (ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ZERO)) {
> +        ret |= BDRV_BLOCK_ALLOCATED;
> +    }
> +

Shouldn't BDRV_BLOCK_ALLOCATED be set in the 
!bs->drv->bdrv_co_get_block_status case as well?

>       if (!(ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO)) {
>           if (bdrv_unallocated_blocks_are_zero(bs)) {
>               ret |= BDRV_BLOCK_ZERO;
> @@ -3959,9 +3963,7 @@ int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num,
>       if (ret < 0) {
>           return ret;
>       }
> -    return
> -        (ret & BDRV_BLOCK_DATA) ||
> -        ((ret & BDRV_BLOCK_ZERO) && !bdrv_has_zero_init(bs));
> +    return (ret & BDRV_BLOCK_ALLOCATED);
>   }
>   
>   /*
> diff --git a/include/block/block.h b/include/block/block.h
> index 2fda81c..ad4c7e8 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h
> @@ -116,6 +116,8 @@ typedef enum {
>   /* BDRV_BLOCK_DATA: data is read from bs->file or another file
>    * BDRV_BLOCK_ZERO: sectors read as zero
>    * BDRV_BLOCK_OFFSET_VALID: sector stored in bs->file as raw data
> + * BDRV_BLOCK_ALLOCATED: the content of the block is determined by this
> + *                       layer (as opposed to the backing file)

I guess this is above BDRV_BLOCK_RAW (albeit having a greater value) 
because it is not only used internally? (to pick up on the topic of OCD :-P)

Max

>    * BDRV_BLOCK_RAW: used internally to indicate that the request
>    *                 was answered by the raw driver and that one
>    *                 should look in bs->file directly.
> @@ -137,10 +139,11 @@ typedef enum {
>    *  f    t        f       not allocated or unknown offset, read as zero
>    *  f    f        f       not allocated or unknown offset, read from backing_hd
>    */
> -#define BDRV_BLOCK_DATA         1
> -#define BDRV_BLOCK_ZERO         2
> -#define BDRV_BLOCK_OFFSET_VALID 4
> -#define BDRV_BLOCK_RAW          8
> +#define BDRV_BLOCK_DATA         0x01
> +#define BDRV_BLOCK_ZERO         0x02
> +#define BDRV_BLOCK_OFFSET_VALID 0x04
> +#define BDRV_BLOCK_RAW          0x08
> +#define BDRV_BLOCK_ALLOCATED    0x10
>   #define BDRV_BLOCK_OFFSET_MASK  BDRV_SECTOR_MASK
>   
>   typedef enum {

Am 06.05.2014 um 21:53 hat Max Reitz geschrieben:
> On 06.05.2014 15:30, Kevin Wolf wrote:
> >bdrv_is_allocated() shouldn't return true for sectors that are
> >unallocated, but after the end of a short backing file, even though
> >such sectors are (correctly) marked as containing zeros.
> >
> >Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> >---
> >  block.c               |  8 +++++---
> >  include/block/block.h | 11 +++++++----
> >  2 files changed, 12 insertions(+), 7 deletions(-)
> >
> >diff --git a/block.c b/block.c
> >index c90c71a..d3a9906 100644
> >--- a/block.c
> >+++ b/block.c
> >@@ -3883,6 +3883,10 @@ static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
> >                                       *pnum, pnum);
> >      }
> >+    if (ret & (BDRV_BLOCK_DATA | BDRV_BLOCK_ZERO)) {
> >+        ret |= BDRV_BLOCK_ALLOCATED;
> >+    }
> >+
> 
> Shouldn't BDRV_BLOCK_ALLOCATED be set in the
> !bs->drv->bdrv_co_get_block_status case as well?

It should. Thanks, I'll send a v2.

> >      if (!(ret & BDRV_BLOCK_DATA) && !(ret & BDRV_BLOCK_ZERO)) {
> >          if (bdrv_unallocated_blocks_are_zero(bs)) {
> >              ret |= BDRV_BLOCK_ZERO;
> >@@ -3959,9 +3963,7 @@ int coroutine_fn bdrv_is_allocated(BlockDriverState *bs, int64_t sector_num,
> >      if (ret < 0) {
> >          return ret;
> >      }
> >-    return
> >-        (ret & BDRV_BLOCK_DATA) ||
> >-        ((ret & BDRV_BLOCK_ZERO) && !bdrv_has_zero_init(bs));
> >+    return (ret & BDRV_BLOCK_ALLOCATED);
> >  }
> >  /*
> >diff --git a/include/block/block.h b/include/block/block.h
> >index 2fda81c..ad4c7e8 100644
> >--- a/include/block/block.h
> >+++ b/include/block/block.h
> >@@ -116,6 +116,8 @@ typedef enum {
> >  /* BDRV_BLOCK_DATA: data is read from bs->file or another file
> >   * BDRV_BLOCK_ZERO: sectors read as zero
> >   * BDRV_BLOCK_OFFSET_VALID: sector stored in bs->file as raw data
> >+ * BDRV_BLOCK_ALLOCATED: the content of the block is determined by this
> >+ *                       layer (as opposed to the backing file)
> 
> I guess this is above BDRV_BLOCK_RAW (albeit having a greater value)
> because it is not only used internally? (to pick up on the topic of
> OCD :-P)

Because it felt right. This may or may not be equivalent.

Kevin