Re: [Qemu-block] [PATCH 4/6] qcow2: Update total_sectors when resizing the image

[Leonid Bloch]

On 07/30/2018 12:43 PM, Kevin Wolf wrote:
> Am 29.07.2018 um 23:27 hat Leonid Bloch geschrieben:
> > Signed-off-by: Leonid Bloch <address@hidden>
> > ---
> >   block/qcow2.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/block/qcow2.c b/block/qcow2.c
> > index ec9e6238a0..223d351e40 100644
> > --- a/block/qcow2.c
> > +++ b/block/qcow2.c
> > @@ -3646,6 +3646,8 @@ static int coroutine_fn 
> > qcow2_co_truncate(BlockDriverState *bs, int64_t offset,
> >           }
> >       }
> >   
> > +    bs->total_sectors = offset / 512;
> > +
> >       /* write updated header.size */
> >       offset = cpu_to_be64(offset);
> >       ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, size),
>
> This shouldn't be necessary, bdrv_co_truncate() already updates
> bs->total_sectors after calling the block driver.

It looks like without it the cache resize works only on the second resize.

> If this is needed by one of the following patches, we need a comment
> that explains why this seemingly superfluous assignment is actually
> necessary.
>
> Also, 512 should be BDRV_SECTOR_SIZE.

I was surprised that it's not, but it's 512 also in two other places, 
including in qcow2_co_truncate itself. So I decided to keep that. 
Probably would be better if I'd repair it in the other places instead. :)

Thanks!
Leonid.

> Kevin