linux-kernel - Re: [PATCH] dax: check return value of dax_radix

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Message-ID: <20160302163346.GA22821@linux.intel.com>
Date:	Wed, 2 Mar 2016 09:33:46 -0700
From:	Ross Zwisler <ross.zwisler@...ux.intel.com>
To:	Matthew Wilcox <willy@...ux.intel.com>
Cc:	Ross Zwisler <ross.zwisler@...ux.intel.com>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dan Williams <dan.j.williams@...el.com>,
	linux-nvdimm@...ts.01.org
Subject: Re: [PATCH] dax: check return value of dax_radix_entry()

On Wed, Mar 02, 2016 at 09:09:47AM -0500, Matthew Wilcox wrote:
> On Tue, Mar 01, 2016 at 03:15:08PM -0700, Ross Zwisler wrote:
> > dax_pfn_mkwrite() previously wasn't checking the return value of the call
> > to dax_radix_entry(), which was a mistake.
> > 
> > Instead, capture this return value and pass it up the stack if it is an
> > error.
> 
> >  	 */
> > -	dax_radix_entry(file->f_mapping, vmf->pgoff, NO_SECTOR, false, true);
> > +	error = dax_radix_entry(file->f_mapping, vmf->pgoff, NO_SECTOR, false,
> > +			true);
> > +	if (error)
> > +		return error;
> > +
> >  	return VM_FAULT_NOPAGE;
> 
> You can't return an errno from here.
> 
> 	if (error)
> 		return VM_FAULT_SIGBUS;
> 
> is better.  For full points,
> 
> 	if (error == -ENOMEM)
> 		return VM_FAULT_OOM;
> 	if (error)
> 		return VM_FAULT_SIGBUS;
> 	return VM_FAULT_NOPAGE;

Ah, thank you for catching that.