On Fri, Apr 07, 2017 at 12:32:45PM +0200, Kevin Wolf wrote: > The assertion is currently failing. We can't require callers to have > write permissions when all they are doing is a read, so comment it out. > Add a FIXME comment in the code so that the check is re-enabled when > copy on read is refactored into its own filter driver. > > Reported-by: Richard W.M. Jones <rjo...@redhat.com> > Signed-off-by: Kevin Wolf <kw...@redhat.com>
Thanks Kevin. As this is essentially the same as the patch I tested last night, Reviewed-by: Richard W.M. Jones <rjo...@redhat.com> Rich. > block/io.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/block/io.c b/block/io.c > index 2709a70..7321dda 100644 > --- a/block/io.c > +++ b/block/io.c > @@ -945,7 +945,14 @@ static int coroutine_fn > bdrv_co_do_copy_on_readv(BdrvChild *child, > size_t skip_bytes; > int ret; > > - assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE)); > + /* FIXME We cannot require callers to have write permissions when all > they > + * are doing is a read request. If we did things right, write permissions > + * would be obtained anyway, but internally by the copy-on-read code. As > + * long as it is implemented here rather than in a separat filter driver, > + * the copy-on-read code doesn't have its own BdrvChild, however, for > which > + * it could request permissions. Therefore we have to bypass the > permission > + * system for the moment. */ > + // assert(child->perm & (BLK_PERM_WRITE_UNCHANGED | BLK_PERM_WRITE)); > > /* Cover entire cluster so no additional backing file I/O is required > when > * allocating cluster in the image file. > -- > 1.8.3.1 -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html
