diff mbox

[v4,15/21] block: return BDRV_BLOCK_ZERO past end of backing file

Message ID 1377784821-29561-16-git-send-email-pbonzini@redhat.com
State New
Headers show

Commit Message

Paolo Bonzini Aug. 29, 2013, 2 p.m. UTC 
If the sectors are unallocated and we are past the end of the
backing file, they will read as zero.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 block.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

Comments

Eric Blake Aug. 29, 2013, 9:59 p.m. UTC | #1 
On 08/29/2013 08:00 AM, Paolo Bonzini wrote:
> If the sectors are unallocated and we are past the end of the
> backing file, they will read as zero.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  block.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)

Reviewed-by: Eric Blake <eblake@redhat.com>
diff mbox

Patch

diff --git a/block.c b/block.c
index ecae287..cf52489 100644
--- a/block.c
+++ b/block.c
@@ -3028,8 +3028,16 @@  static int64_t coroutine_fn bdrv_co_get_block_status(BlockDriverState *bs,
         return ret;
     }
 
-    if (!(ret & BDRV_BLOCK_DATA) && bdrv_has_zero_init(bs)) {
-        ret |= BDRV_BLOCK_ZERO;
+    if (!(ret & BDRV_BLOCK_DATA)) {
+        if (bdrv_has_zero_init(bs)) {
+            ret |= BDRV_BLOCK_ZERO;
+        } else {
+            BlockDriverState *bs2 = bs->backing_hd;
+            int64_t length2 = bdrv_getlength(bs2);
+            if (length2 >= 0 && sector_num >= (length2 >> BDRV_SECTOR_BITS)) {
+                ret |= BDRV_BLOCK_ZERO;
+            }
+        }
     }
     return ret;
 }