Re: [PATCH] daxctl: Fix memblock enumeration off-by-one

[Eliot Moss <moss@cs.umass.edu>]

On 2/3/2023 11:11 AM, Dan Williams wrote:
> Eliot Moss wrote:
>> On 2/3/2023 7:56 AM, Dan Williams wrote:
>>> A memblock is an inclusive memory range. Bound the search by the last
>>> address in the memory block.
>>>
>>> Found by wondering why an offline 32-block (at 128MB == 4GB) range was
>>> reported as 33 blocks with one online.
>>>
>>> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
>>> ---
>>>    daxctl/lib/libdaxctl.c |    2 +-
>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/daxctl/lib/libdaxctl.c b/daxctl/lib/libdaxctl.c
>>> index 5703992f5b88..d990479d8585 100644
>>> --- a/daxctl/lib/libdaxctl.c
>>> +++ b/daxctl/lib/libdaxctl.c
>>> @@ -1477,7 +1477,7 @@ static int memblock_in_dev(struct daxctl_memory *mem, const char *memblock)
>>>    		err(ctx, "%s: Unable to determine resource\n", devname);
>>>    		return -EACCES;
>>>    	}
>>> -	dev_end = dev_start + daxctl_dev_get_size(dev);
>>> +	dev_end = dev_start + daxctl_dev_get_size(dev) - 1;
>>>    
>>>    	memblock_size = daxctl_memory_get_block_size(mem);
>>>    	if (!memblock_size) {
>>
>> Might this address the bug I reported?
> 
> This one?
> 
> http://lore.kernel.org/r/558d0ff1-4658-a11b-5a6d-0be0a3a6799c@cs.umass.edu
> 
> I don't think so, that one seems to have something to do with the file
> extent layout that causes fs/dax.c to fallback to 4K mappings.

That was the one - I think you're right; it's not immediately related.

EM