On Thu, Apr 11, 2019 at 7:00 AM Stefano Garzarella <sgarz...@redhat.com> 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 RW operations that exceed the current size.
What's the use-case for storing qcow2 images within a RBD image? RBD images are already thinly provisioned, they support snapshots, they can form a parent/child linked image hierarchy. > Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1171007 > Signed-off-by: Stefano Garzarella <sgarz...@redhat.com> > --- > block/rbd.c | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > > diff --git a/block/rbd.c b/block/rbd.c > index 0c549c9935..228658e20a 100644 > --- a/block/rbd.c > +++ b/block/rbd.c > @@ -102,6 +102,7 @@ typedef struct BDRVRBDState { > rbd_image_t image; > char *image_name; > char *snap; > + uint64_t image_size; > } BDRVRBDState; > > static int qemu_rbd_connect(rados_t *cluster, rados_ioctx_t *io_ctx, > @@ -777,6 +778,14 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict > *options, int flags, > goto failed_open; > } > > + r = rbd_get_size(s->image, &s->image_size); > + if (r < 0) { > + error_setg_errno(errp, -r, "error reading image size from %s", > + s->image_name); > + rbd_close(s->image); > + goto failed_open; > + } > + > /* If we are using an rbd snapshot, we must be r/o, otherwise > * leave as-is */ > if (s->snap != NULL) { > @@ -921,6 +930,20 @@ static BlockAIOCB *rbd_start_aio(BlockDriverState *bs, > rcb->buf = acb->bounce; > } > > + /* > + * RBD APIs don't allow us to write more than actual size, so in order > + * to support growing images, we resize the image before RW operations > + * that exceed the current size. > + */ > + if (s->image_size < off + size) { > + r = rbd_resize(s->image, off + size); > + if (r < 0) { > + goto failed; > + } > + > + s->image_size = off + size; > + } > + > acb->ret = 0; > acb->error = 0; > acb->s = s; > @@ -1066,6 +1089,8 @@ static int coroutine_fn > qemu_rbd_co_truncate(BlockDriverState *bs, > return r; > } > > + s->image_size = offset; > + > return 0; > } > > -- > 2.20.1 > > -- Jason