Re: [PATCH v9 5/7] config: add check to block layer

[Sam Li]

Damien Le Moal <damien.lemoal@opensource.wdc.com> 于2022年9月11日周日 13:34写道：
>
> On 2022/09/10 14:27, Sam Li wrote:
> > Putting zoned/non-zoned BlockDrivers on top of each other is not
> > allowed.
> >
> > Signed-off-by: Sam Li <faithilikerun@gmail.com>
> > Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> > ---
> >  block.c                          | 14 ++++++++++++++
> >  block/file-posix.c               | 14 ++++++++++++++
> >  block/raw-format.c               |  1 +
> >  include/block/block_int-common.h |  5 +++++
> >  4 files changed, 34 insertions(+)
> >
> > diff --git a/block.c b/block.c
> > index bc85f46eed..dad2ed3959 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) {
>
> Shouldn't this be "child_bs->bl.zoned != BLK_Z_NONE" ?

The host-aware model allows zoned storage constraints(sequentially
write) and random write. Is mixing HA and non-zoned drivers allowed?
What's the difference?

>
> > +        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/file-posix.c b/block/file-posix.c
> > index 4edfa25d04..354de22860 100644
> > --- a/block/file-posix.c
> > +++ b/block/file-posix.c
> > @@ -779,6 +779,20 @@ static int raw_open_common(BlockDriverState *bs, QDict 
> > *options,
> >              goto fail;
> >          }
> >      }
> > +#ifdef CONFIG_BLKZONED
> > +    /*
> > +     * The kernel page chache does not reliably work for writes to SWR 
> > zones
> > +     * of zoned block device because it can not guarantee the order of 
> > writes.
> > +     */
> > +    if (strcmp(bs->drv->format_name, "zoned_host_device") == 0) {
> > +        if (!(s->open_flags & O_DIRECT)) {
> > +            error_setg(errp, "driver=zoned_host_device was specified, but 
> > it "
> > +                             "requires cache.direct=on, which was not 
> > specified.");
> > +            ret = -EINVAL;
>
> This line is not needed. Simply "return -EINVAL;".
>
> > +            return ret; /* No host kernel page cache */
> > +        }
> > +    }
> > +#endif
> >
> >      if (S_ISBLK(st.st_mode)) {
> >  #ifdef BLKDISCARDZEROES
> > 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 078ddd7e67..043aa161a0 100644
> > --- a/include/block/block_int-common.h
> > +++ b/include/block/block_int-common.h
> > @@ -127,6 +127,11 @@ 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
>
> --
> Damien Le Moal
> Western Digital Research
>