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SubjectRe: [PATCH v3 05/15] libnvdimm, pmem: fix size trim in pmem_direct_access()
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On Tue, Nov 3, 2015 at 11:32 AM, Ross Zwisler
<ross.zwisler@linux.intel.com> wrote:
> On Sun, Nov 01, 2015 at 11:30:10PM -0500, Dan Williams wrote:
>> This masking prevents access to the end of the device via dax_do_io(),
>> and is unnecessary as arch_add_memory() would have rejected an unaligned
>> allocation.
>>
>> Cc: <stable@vger.kernel.org>
>> Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
>> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
>> ---
>> drivers/nvdimm/pmem.c | 17 +++--------------
>> 1 file changed, 3 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/nvdimm/pmem.c b/drivers/nvdimm/pmem.c
>> index e46988fbdee5..93472953e231 100644
>> --- a/drivers/nvdimm/pmem.c
>> +++ b/drivers/nvdimm/pmem.c
>> @@ -100,26 +100,15 @@ static int pmem_rw_page(struct block_device *bdev, sector_t sector,
>> }
>>
>> static long pmem_direct_access(struct block_device *bdev, sector_t sector,
>> - void __pmem **kaddr, unsigned long *pfn)
>> + void __pmem **kaddr, pfn_t *pfn)
>
> It seems kind of weird to change only this instance of direct_access() to have
> the last argument as a pfn_t instead of an unsigned long? If pfn_t is more
> descriptive (I think it is) should we update the definition in struct
> block_device_operations and all the other implementors of direct_access as
> well? If that's touching too much, let's do them all together later, but
> let's not change one now and have them be inconsistent.
>

Oh, nice catch, that's just a mistake when I moved this patch earlier
in the series... and I wonder why 0day didn't complain about it? In
any event, will fix.

>> {
>> struct pmem_device *pmem = bdev->bd_disk->private_data;
>> resource_size_t offset = sector * 512 + pmem->data_offset;
>> - resource_size_t size;
>>
>> - if (pmem->data_offset) {
>> - /*
>> - * Limit the direct_access() size to what is covered by
>> - * the memmap
>> - */
>> - size = (pmem->size - offset) & ~ND_PFN_MASK;
>> - } else
>> - size = pmem->size - offset;
>> -
>> - /* FIXME convert DAX to comprehend that this mapping has a lifetime */
>> *kaddr = pmem->virt_addr + offset;
>> - *pfn = (pmem->phys_addr + offset) >> PAGE_SHIFT;
>> + *pfn = __phys_to_pfn(pmem->phys_addr + offset, pmem->pfn_flags);
>
> __phys_to_pfn() only takes a single argument (the paddr) in v4.3,
> jens/for-4.4/integrity and in nvdimm/libnvdimm-for-next. Is this second
> argument of pfn_flags actually correct?

Yeah, this shouldn't even compile.

Thanks Ross!


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