Re: [PATCH 11/12] device-dax: Add dis-contiguous resource support

From: Joao Martins
Date: Thu Mar 26 2020 - 13:50:05 EST


On 3/25/20 5:48 PM, Dan Williams wrote:
> On Wed, Mar 25, 2020 at 3:35 AM Joao Martins <joao.m.martins@xxxxxxxxxx> wrote:
>> On 3/24/20 4:12 PM, Joao Martins wrote:
>>> On 3/23/20 11:55 PM, Dan Williams wrote:
>>>> static ssize_t dev_dax_resize(struct dax_region *dax_region,
>>>> struct dev_dax *dev_dax, resource_size_t size)
>>>> {
>>>> resource_size_t avail = dax_region_avail_size(dax_region), to_alloc;
>>>> - resource_size_t dev_size = range_len(&dev_dax->range);
>>>> + resource_size_t dev_size = dev_dax_size(dev_dax);
>>>> struct resource *region_res = &dax_region->res;
>>>> struct device *dev = &dev_dax->dev;
>>>> - const char *name = dev_name(dev);
>>>> struct resource *res, *first;
>>>> + resource_size_t alloc = 0;
>>>> + int rc;
>>>>
>>>> if (dev->driver)
>>>> return -EBUSY;
>>>> @@ -684,38 +766,47 @@ static ssize_t dev_dax_resize(struct dax_region *dax_region,
>>>> * allocating a new resource.
>>>> */
>>>> first = region_res->child;
>>>> - if (!first)
>>>> - return __alloc_dev_dax_range(dev_dax, dax_region->res.start,
>>>> - to_alloc);
>>>
>>> You probably want to retain the condition above?
>>>
>>> Otherwise it removes the ability to create new devices or resizing it , once we
>>> have zero-ed the last one.
>>>
>>
>> A quick unit test that I had stashed here to help explain what I mean:
>>
>> cd /sys/bus/dax/devices
>> # dax0.0 is the only dax device in the corresponding dax_region
>> echo dax0.0 > dax0.0/driver/unbind
>> echo 0 > dax0.0/size
>> # Shouldn't fail but returns -ENOSPC despite having
>> # the full region available
>> cat $(readlink -f dax0.0/../dax_region/available_size) > dax0.0/size
>
> Thanks! Will incorporate that test before resending the series.
>
I'll also add some of these tests (in ndctl.git:tests/daxctl-{devices.sh) as
part of my daxctl counterpart series (except using daxctl equivalent of the above).

Joao