On Tue, Jun 25, 2019 at 04:02:04PM +0200, Max Reitz wrote:
> On 09.05.19 16:59, Stefano Garzarella wrote:
> > RBD APIs don't allow us to write more than the size set with
> > rbd_create() or rbd_resize().
> > In order to support growing images (eg. qcow2), we resize the
> > image before write operations that exceed the current size.
> >
> > Signed-off-by: Stefano Garzarella <sgarz...@redhat.com>
> > ---
> > v3:
> > - add 'image_size' field in the BDRVRBDState to keep track of the
> > current size of the RBD image [Jason, Kevin]
> > ---
> > block/rbd.c | 42 +++++++++++++++++++++++++++++++++++++++---
> > 1 file changed, 39 insertions(+), 3 deletions(-)
> >
> > diff --git a/block/rbd.c b/block/rbd.c
> > index 0c549c9935..b0355a2ce0 100644
> > --- a/block/rbd.c
> > +++ b/block/rbd.c
>
> [...]
>
> > @@ -833,6 +842,22 @@ static void qemu_rbd_close(BlockDriverState *bs)
> > rados_shutdown(s->cluster);
> > }
> >
> > +/* Resize the RBD image and update the 'image_size' with the current size
> > */
> > +static int qemu_rbd_resize(BlockDriverState *bs, uint64_t size)
> > +{
> > + BDRVRBDState *s = bs->opaque;
> > + int r;
> > +
> > + r = rbd_resize(s->image, size);
> > + if (r < 0) {
> > + return r;
> > + }
> > +
> > + s->image_size = size;
>
> I think this should update bs->total_sectors, too. In fact, I’m
> wondering why you don’t just use bs->total_sectors (or bdrv_getlength(),
> which returns bs->total_sectors * 512) instead of adding this new field?
>
Hi Max,
thanks for taking a look!
I used bs->total_sectors in the v2, but Jason pointed out a possible
issue with this, so I proposed to add a variable in the BDRVRBDState to
track the latest resize and Kevin acked [1].
IIUC what Kevin said on his comment, the 'bs->total_sectors' should be
updated by bdrv_co_write_req_finish(), for this reason I didn't update
it.
[1] https://www.mail-archive.com/qemu-devel@nongnu.org/msg615195.html
Thanks,
Stefano
