Am 01.05.2015 um 16:23 hat Stefan Hajnoczi geschrieben:
> On Thu, Apr 30, 2015 at 01:11:40PM +0300, Alberto Garcia wrote:
> > Qcow2Cache *qcow2_cache_create(BlockDriverState *bs, int num_tables)
> > {
> > BDRVQcowState *s = bs->opaque;
> > Qcow2Cache *c;
> > - int i;
> >
> > c = g_new0(Qcow2Cache, 1);
> > c->size = num_tables;
> > + c->table_size = s->cluster_size;
>
> This assumes c->table_size meets bs' memory alignment requirements. The
> following would be safer:
>
> c->table_size = QEMU_ALIGN_UP(c->table_size, bdrv_opt_mem_align(bs->file));You can't just access more than one cluster. You might be caching data and later write it back when it's stale. If you can't do I/O in chunks as small as the cluster size (which is rather unlikely), relying on bdrv_pwrite(), like Berto's patch does, is the correct solution. Kevin
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