[PATCH] qcow2: set bdi->is_dirty

[PATCH] qcow2: set bdi->is_dirty

[Vladimir Sementsov-Ogievskiy]

Set bdi->is_dirty, so that qemu-img info could show dirty flag.

After this commit the following check will show '"dirty-flag": true':

./build/qemu-img create -f qcow2 -o lazy_refcounts=on x 1M
./build/qemu-io x
qemu-io> write 0 1M

 After "write" command success, kill the qemu-io process:

kill -9 <qemu-io pid>

./build/qemu-img info --output=json x

This will show '"dirty-flag": true' among other things. (before this
commit it shows '"dirty-flag": false')

Note, that qcow2's dirty-bit is not a "dirty bit for the image". It
only protects qcow2 lazy refcounts feature. So, there are a lot of
conditions when qcow2 session may be not closed correctly, but bit is
0. Still, when bit is set, the last session is definitely not finished
correctly and it's better to report it.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
---
 block/qcow2.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/block/qcow2.c b/block/qcow2.c
index 9727ae8fe3..39b91ef940 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -5089,6 +5089,7 @@ static int qcow2_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
     BDRVQcow2State *s = bs->opaque;
     bdi->cluster_size = s->cluster_size;
     bdi->vm_state_offset = qcow2_vm_state_offset(s);
+    bdi->is_dirty = s->incompatible_features & QCOW2_INCOMPAT_DIRTY;
     return 0;
 }
 
-- 
2.29.2

Re: [PATCH] qcow2: set bdi->is_dirty

[Eric Blake]

On 5/4/21 11:06 AM, Vladimir Sementsov-Ogievskiy wrote:
> Set bdi->is_dirty, so that qemu-img info could show dirty flag.
> 
> After this commit the following check will show '"dirty-flag": true':
> 
> ./build/qemu-img create -f qcow2 -o lazy_refcounts=on x 1M
> ./build/qemu-io x
> qemu-io> write 0 1M
> 
>  After "write" command success, kill the qemu-io process:
> 
> kill -9 <qemu-io pid>
> 
> ./build/qemu-img info --output=json x
> 
> This will show '"dirty-flag": true' among other things. (before this
> commit it shows '"dirty-flag": false')
> 
> Note, that qcow2's dirty-bit is not a "dirty bit for the image". It
> only protects qcow2 lazy refcounts feature. So, there are a lot of
> conditions when qcow2 session may be not closed correctly, but bit is
> 0. Still, when bit is set, the last session is definitely not finished
> correctly and it's better to report it.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  block/qcow2.c | 1 +
>  1 file changed, 1 insertion(+)

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


-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org

Re: [PATCH] qcow2: set bdi->is_dirty

[Kirill Tkhai]

On 04.05.2021 19:06, Vladimir Sementsov-Ogievskiy wrote:
> Set bdi->is_dirty, so that qemu-img info could show dirty flag.
> 
> After this commit the following check will show '"dirty-flag": true':
> 
> ./build/qemu-img create -f qcow2 -o lazy_refcounts=on x 1M
> ./build/qemu-io x
> qemu-io> write 0 1M
> 
>  After "write" command success, kill the qemu-io process:
> 
> kill -9 <qemu-io pid>
> 
> ./build/qemu-img info --output=json x
> 
> This will show '"dirty-flag": true' among other things. (before this
> commit it shows '"dirty-flag": false')
> 
> Note, that qcow2's dirty-bit is not a "dirty bit for the image". It
> only protects qcow2 lazy refcounts feature. So, there are a lot of
> conditions when qcow2 session may be not closed correctly, but bit is
> 0. Still, when bit is set, the last session is definitely not finished
> correctly and it's better to report it.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Works for me. Thanks,

Tested-by: Kirill Tkhai <ktkhai@virtuozzo.com>

> ---
>  block/qcow2.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/block/qcow2.c b/block/qcow2.c
> index 9727ae8fe3..39b91ef940 100644
> --- a/block/qcow2.c
> +++ b/block/qcow2.c
> @@ -5089,6 +5089,7 @@ static int qcow2_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
>      BDRVQcow2State *s = bs->opaque;
>      bdi->cluster_size = s->cluster_size;
>      bdi->vm_state_offset = qcow2_vm_state_offset(s);
> +    bdi->is_dirty = s->incompatible_features & QCOW2_INCOMPAT_DIRTY;
>      return 0;
>  }
>  
> 

Re: [PATCH] qcow2: set bdi->is_dirty

[Kevin Wolf]

Am 04.05.2021 um 18:06 hat Vladimir Sementsov-Ogievskiy geschrieben:
> Set bdi->is_dirty, so that qemu-img info could show dirty flag.
> 
> After this commit the following check will show '"dirty-flag": true':
> 
> ./build/qemu-img create -f qcow2 -o lazy_refcounts=on x 1M
> ./build/qemu-io x
> qemu-io> write 0 1M
> 
>  After "write" command success, kill the qemu-io process:
> 
> kill -9 <qemu-io pid>
> 
> ./build/qemu-img info --output=json x
> 
> This will show '"dirty-flag": true' among other things. (before this
> commit it shows '"dirty-flag": false')
> 
> Note, that qcow2's dirty-bit is not a "dirty bit for the image". It
> only protects qcow2 lazy refcounts feature. So, there are a lot of
> conditions when qcow2 session may be not closed correctly, but bit is
> 0. Still, when bit is set, the last session is definitely not finished
> correctly and it's better to report it.
> 
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

Thanks, applied to the block branch.

Kevin