Re: [PATCH] dax: check return value of dax_radix_entry()

[Matthew Wilcox]

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;