Re: [PATCH] nvdimm: Remove minimum size requirement

From: Matthew Wilcox <willy@infradead.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Cheng-mean Liu <soccerl@microsoft.com>,
	Matthew Wilcox <mawilcox@microsoft.com>,
	"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>
Subject: Re: [PATCH] nvdimm: Remove minimum size requirement
Date: Mon, 10 Jul 2017 13:30:12 -0700	[thread overview]
Message-ID: <20170710203012.GB22476@bombadil.infradead.org> (raw)
In-Reply-To: <CAPcyv4ioWUmiHbaGVcpxuK-j0JrcGk-_VcpR6yQtQMUwcRTRcQ@mail.gmail.com>

On Mon, Jul 10, 2017 at 11:41:08AM -0700, Dan Williams wrote:
> >         size = nvdimm_namespace_capacity(ndns);
> > -       if (size < ND_MIN_NAMESPACE_SIZE) {
> > -               dev_dbg(&ndns->dev, "%pa, too small must be at least %#x\n",
> > -                               &size, ND_MIN_NAMESPACE_SIZE);
> > +       if (size < PAGE_SIZE) {
> 
> If we're going to change the print level away from 'debug' then I
> think this should be "if (size && size < PAGE_SIZE)". The sub-system
> pre-creates 0-sized devices that are later configured into full
> namespaces, in those cases we shouldn't fire the warning.

Should we allow drivers to claim zero-sized devices?  If not, then the
dev_warn() should be predicated on size being non-zero, but the return
-ENODEV should still trigger.
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