Stefan Hajnoczi <stefa...@redhat.com> 于2022年8月23日周二 08:54写道：
>
> On Tue, Aug 16, 2022 at 02:25:20PM +0800, Sam Li wrote:
> > Putting zoned/non-zoned BlockDrivers on top of each other is not
> > allowed.
> >
> > Signed-off-by: Sam Li <faithilike...@gmail.com>
> > Reviewed-by: Stefan Hajnoczi <stefa...@redhat.com>
> > ---
> > block.c | 14 ++++++++++++++
> > block/raw-format.c | 1 +
> > include/block/block_int-common.h | 5 +++++
> > 3 files changed, 20 insertions(+)
> >
> > diff --git a/block.c b/block.c
> > index bc85f46eed..affe6c597e 100644
> > --- a/block.c
> > +++ b/block.c
> > @@ -7947,6 +7947,20 @@ void bdrv_add_child(BlockDriverState *parent_bs,
> > BlockDriverState *child_bs,
> > return;
> > }
> >
> > + /*
> > + * Non-zoned block drivers do not follow zoned storage constraints
> > + * (i.e. sequential writes to zones). Refuse mixing zoned and non-zoned
> > + * drivers in a graph.
> > + */
> > + if (!parent_bs->drv->supports_zoned_children &&
> > + child_bs->bl.zoned != BLK_Z_HM) {
>
Should be:
+if (!parent_bs->drv->supports_zoned_children &&
+ child_bs->bl.zoned == BLK_Z_HM)
> Is this logical expression correct:
>
> If the parent does not support zoned children and the child is not
> zoned, fail with an error.
>
> ?
No. It should be:
If the parent does not support zoned children and the child is zoned,
fail with an error. It should handle the case where a filter node is
inserted above a raw block driver with a zoned_host_device child.
There are some QEMU command-line constraints for the zoned devices. I
was wondering where to add such support so that it can print an error
message for users:
1. cache.direct= setting
2. mix zoned/non-zoned drivers
>
> > + error_setg(errp, "Cannot add a %s child to a %s parent",
> > + child_bs->bl.zoned == BLK_Z_HM ? "zoned" : "non-zoned",
> > + parent_bs->drv->supports_zoned_children ?
> > + "support zoned children" : "not support zoned
> > children");
> > + return;
> > + }
> > +
> > if (!QLIST_EMPTY(&child_bs->parents)) {
> > error_setg(errp, "The node %s already has a parent",
> > child_bs->node_name);
> > diff --git a/block/raw-format.c b/block/raw-format.c
> > index 6b20bd22ef..9441536819 100644
> > --- a/block/raw-format.c
> > +++ b/block/raw-format.c
> > @@ -614,6 +614,7 @@ static void raw_child_perm(BlockDriverState *bs,
> > BdrvChild *c,
> > BlockDriver bdrv_raw = {
> > .format_name = "raw",
> > .instance_size = sizeof(BDRVRawState),
> > + .supports_zoned_children = true,
> > .bdrv_probe = &raw_probe,
> > .bdrv_reopen_prepare = &raw_reopen_prepare,
> > .bdrv_reopen_commit = &raw_reopen_commit,
> > diff --git a/include/block/block_int-common.h
> > b/include/block/block_int-common.h
> > index de44c7b6f4..4c44592b59 100644
> > --- a/include/block/block_int-common.h
> > +++ b/include/block/block_int-common.h
> > @@ -126,6 +126,11 @@ struct BlockDriver {
> > */
> > bool is_format;
> >
> > + /*
> > + * Set to true if the BlockDriver supports zoned children.
> > + */
> > + bool supports_zoned_children;
> > +
> > /*
> > * Drivers not implementing bdrv_parse_filename nor bdrv_open should
> > have
> > * this field set to true, except ones that are defined only by their
> > --
> > 2.37.1
> >
