From: Dan Williams <dan.j.williams@intel.com>
To: Mike Snitzer <snitzer@redhat.com>
Cc: kbuild test robot <lkp@intel.com>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
dm-devel@redhat.com, Bart Van Assche <Bart.VanAssche@wdc.com>,
Alasdair Kergon <agk@redhat.com>
Subject: Re: [PATCH v3 2/2] dm: allow device-mapper to operate without dax support
Date: Mon, 11 Sep 2017 08:56:01 -0700 [thread overview]
Message-ID: <CAPcyv4gBLPsogW_SUkBuAnZggP1WZqkNZZrxFZef7pmGFFFNkA@mail.gmail.com> (raw)
In-Reply-To: <20170911144111.GA15556@redhat.com>
On Mon, Sep 11, 2017 at 7:41 AM, Mike Snitzer <snitzer@redhat.com> wrote:
> On Wed, Aug 02 2017 at 1:58pm -0400,
> Dan Williams <dan.j.williams@intel.com> wrote:
>
>> Rather than have device-mapper directly 'select DAX', let the fact that
>> BLK_DEV_PMEM selects dax act as a gate for the device-mapper dax
>> support. We arrange for all the dax core routines to compile to nops
>> when CONFIG_DAX=n. With that in place we can simply handle the
>> alloc_dax() error as expected and ifdef out the other device-mapper-dax
>> support code.
>>
>> Now, if dax is provided by a leaf driver that driver may only arrange to
>> compile the dax core as a module. Since device-mapper dax support is
>> consumed by the always-built-in portion of the device-mapper
>> implementation we need to upgrade from DAX=m to DAX=y.
>
> I applied the patches and then got nervous once I dug in.. this last
> paragraph makes little sense to me. "the always-built-in portion of the
> device-mapper implementation" is why: DM core can happily be compiled as
> a module (dm-mod.ko).
>
> And I'm not sure why you're referencing DAX related
> drivers/md/dm-builtin.c, why are you attachd DM's DAX support to that?
> I'm not seeing where that is actually happening.
>
> I don't see why DM's support for DAX would need to force DAX to be
> builtin rather than just a module.
>
> Sorry I didn't get around to looking at this until now, but it seems you
> went wrong along the way? Or maybe I'm just missing something?
>
No, my fault, I didn't track BLK_DEV_DM_BUILTIN correctly and we can
safely make DAX a module when CONFIG_BLK_DEV_DM=m. I'll fix that up,
thanks for the catch.
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WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com>
To: Mike Snitzer <snitzer@redhat.com>
Cc: kbuild test robot <lkp@intel.com>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
dm-devel@redhat.com, Bart Van Assche <Bart.VanAssche@wdc.com>,
Alasdair Kergon <agk@redhat.com>
Subject: Re: [PATCH v3 2/2] dm: allow device-mapper to operate without dax support
Date: Mon, 11 Sep 2017 08:56:01 -0700 [thread overview]
Message-ID: <CAPcyv4gBLPsogW_SUkBuAnZggP1WZqkNZZrxFZef7pmGFFFNkA@mail.gmail.com> (raw)
In-Reply-To: <20170911144111.GA15556@redhat.com>
On Mon, Sep 11, 2017 at 7:41 AM, Mike Snitzer <snitzer@redhat.com> wrote:
> On Wed, Aug 02 2017 at 1:58pm -0400,
> Dan Williams <dan.j.williams@intel.com> wrote:
>
>> Rather than have device-mapper directly 'select DAX', let the fact that
>> BLK_DEV_PMEM selects dax act as a gate for the device-mapper dax
>> support. We arrange for all the dax core routines to compile to nops
>> when CONFIG_DAX=n. With that in place we can simply handle the
>> alloc_dax() error as expected and ifdef out the other device-mapper-dax
>> support code.
>>
>> Now, if dax is provided by a leaf driver that driver may only arrange to
>> compile the dax core as a module. Since device-mapper dax support is
>> consumed by the always-built-in portion of the device-mapper
>> implementation we need to upgrade from DAX=m to DAX=y.
>
> I applied the patches and then got nervous once I dug in.. this last
> paragraph makes little sense to me. "the always-built-in portion of the
> device-mapper implementation" is why: DM core can happily be compiled as
> a module (dm-mod.ko).
>
> And I'm not sure why you're referencing DAX related
> drivers/md/dm-builtin.c, why are you attachd DM's DAX support to that?
> I'm not seeing where that is actually happening.
>
> I don't see why DM's support for DAX would need to force DAX to be
> builtin rather than just a module.
>
> Sorry I didn't get around to looking at this until now, but it seems you
> went wrong along the way? Or maybe I'm just missing something?
>
No, my fault, I didn't track BLK_DEV_DM_BUILTIN correctly and we can
safely make DAX a module when CONFIG_BLK_DEV_DM=m. I'll fix that up,
thanks for the catch.
WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
To: Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: kbuild test robot <lkp-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
"linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org"
<linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org>,
"linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
Bart Van Assche <Bart.VanAssche-Sjgp3cTcYWE@public.gmane.org>,
Alasdair Kergon <agk-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH v3 2/2] dm: allow device-mapper to operate without dax support
Date: Mon, 11 Sep 2017 08:56:01 -0700 [thread overview]
Message-ID: <CAPcyv4gBLPsogW_SUkBuAnZggP1WZqkNZZrxFZef7pmGFFFNkA@mail.gmail.com> (raw)
In-Reply-To: <20170911144111.GA15556-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
On Mon, Sep 11, 2017 at 7:41 AM, Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> On Wed, Aug 02 2017 at 1:58pm -0400,
> Dan Williams <dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> wrote:
>
>> Rather than have device-mapper directly 'select DAX', let the fact that
>> BLK_DEV_PMEM selects dax act as a gate for the device-mapper dax
>> support. We arrange for all the dax core routines to compile to nops
>> when CONFIG_DAX=n. With that in place we can simply handle the
>> alloc_dax() error as expected and ifdef out the other device-mapper-dax
>> support code.
>>
>> Now, if dax is provided by a leaf driver that driver may only arrange to
>> compile the dax core as a module. Since device-mapper dax support is
>> consumed by the always-built-in portion of the device-mapper
>> implementation we need to upgrade from DAX=m to DAX=y.
>
> I applied the patches and then got nervous once I dug in.. this last
> paragraph makes little sense to me. "the always-built-in portion of the
> device-mapper implementation" is why: DM core can happily be compiled as
> a module (dm-mod.ko).
>
> And I'm not sure why you're referencing DAX related
> drivers/md/dm-builtin.c, why are you attachd DM's DAX support to that?
> I'm not seeing where that is actually happening.
>
> I don't see why DM's support for DAX would need to force DAX to be
> builtin rather than just a module.
>
> Sorry I didn't get around to looking at this until now, but it seems you
> went wrong along the way? Or maybe I'm just missing something?
>
No, my fault, I didn't track BLK_DEV_DM_BUILTIN correctly and we can
safely make DAX a module when CONFIG_BLK_DEV_DM=m. I'll fix that up,
thanks for the catch.
next prev parent reply other threads:[~2017-09-11 15:53 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-02 17:57 [PATCH v3 0/2] dax, dm: stop requiring dax for device-mapper Dan Williams
2017-08-02 17:57 ` Dan Williams
2017-08-02 17:58 ` [PATCH v3 1/2] dax: introduce CONFIG_DAX_DRIVER Dan Williams
2017-08-02 17:58 ` Dan Williams
2017-08-02 17:58 ` Dan Williams
2017-08-02 17:58 ` [PATCH v3 2/2] dm: allow device-mapper to operate without dax support Dan Williams
2017-08-02 17:58 ` Dan Williams
2017-09-11 14:41 ` Mike Snitzer
2017-09-11 14:41 ` Mike Snitzer
2017-09-11 15:56 ` Dan Williams [this message]
2017-09-11 15:56 ` Dan Williams
2017-09-11 15:56 ` Dan Williams
2017-08-02 18:55 ` [PATCH v3 0/2] dax, dm: stop requiring dax for device-mapper Mike Snitzer
2017-08-02 18:55 ` Mike Snitzer
2017-08-02 18:55 ` Mike Snitzer
2017-09-09 18:56 ` Dan Williams
2017-09-09 18:56 ` Dan Williams
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