From: Dan Williams <dan.j.williams@intel.com>
To: "hch@lst.de" <hch@lst.de>
Cc: "axboe@kernel.dk" <axboe@kernel.dk>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"riel@redhat.com" <riel@redhat.com>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"david@fromorbit.com" <david@fromorbit.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"mingo@kernel.org" <mingo@kernel.org>,
"axboe@fb.com" <axboe@fb.com>,
"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
"mgorman@suse.de" <mgorman@suse.de>,
"j.glisse@gmail.com" <j.glisse@gmail.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>
Subject: Re: [PATCH v3 06/11] scatterlist: support "page-less" (__pfn_t only) entries
Date: Sat, 23 May 2015 09:41:45 -0700 [thread overview]
Message-ID: <CAA9_cmeD0245sggWkKnK9ur2q3fAYH3+Cr_ddQgKWfcKo1OtEQ@mail.gmail.com> (raw)
In-Reply-To: <20150523141209.GA19414@lst.de>
On Sat, May 23, 2015 at 7:12 AM, hch@lst.de <hch@lst.de> wrote:
> On Wed, May 13, 2015 at 06:35:55PM +0000, Williams, Dan J wrote:
>> Jens, I'm wondering if you want to take this series(.) as patches or
>> prepare a git branch to pull?
>
> Honestly I don't think it should go anyway. It makes a big mess of
> a structure without providing a real user for it. Given how we are
> using the bio_vec for in-kernel page based I/O these days it seems
> like a very dangerous idea.
There's nothing dangerous about the __pfn_t conversion of the block
layer in the !CONFIG_DEV_PFN case a __pfn_t based bio_vec is
bit-for-bit identical to a struct page based bio_vec. However, you're
right, I can't make the same claim about a scatterlist before and
after the change.
Hmm, we're missing a pfn-only block I/O user and we're missing the
second half of the implementation that provides __pfn_t_to_page() for
persistent memory. I'm looking to have a solution __pfn_t_to_page()
shortly, maybe that will allow the scatterlist changes to be
skipped... we'll see.
WARNING: multiple messages have this Message-ID (diff)
From: Dan Williams <dan.j.williams@intel.com>
To: "hch@lst.de" <hch@lst.de>
Cc: "axboe@kernel.dk" <axboe@kernel.dk>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"riel@redhat.com" <riel@redhat.com>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@ml01.01.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"david@fromorbit.com" <david@fromorbit.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"mingo@kernel.org" <mingo@kernel.org>,
"axboe@fb.com" <axboe@fb.com>,
"dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
"mgorman@suse.de" <mgorman@suse.de>,
"j.glisse@gmail.com" <j.glisse@gmail.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>
Subject: Re: [PATCH v3 06/11] scatterlist: support "page-less" (__pfn_t only) entries
Date: Sat, 23 May 2015 09:41:45 -0700 [thread overview]
Message-ID: <CAA9_cmeD0245sggWkKnK9ur2q3fAYH3+Cr_ddQgKWfcKo1OtEQ@mail.gmail.com> (raw)
In-Reply-To: <20150523141209.GA19414@lst.de>
On Sat, May 23, 2015 at 7:12 AM, hch@lst.de <hch@lst.de> wrote:
> On Wed, May 13, 2015 at 06:35:55PM +0000, Williams, Dan J wrote:
>> Jens, I'm wondering if you want to take this series(.) as patches or
>> prepare a git branch to pull?
>
> Honestly I don't think it should go anyway. It makes a big mess of
> a structure without providing a real user for it. Given how we are
> using the bio_vec for in-kernel page based I/O these days it seems
> like a very dangerous idea.
There's nothing dangerous about the __pfn_t conversion of the block
layer in the !CONFIG_DEV_PFN case a __pfn_t based bio_vec is
bit-for-bit identical to a struct page based bio_vec. However, you're
right, I can't make the same claim about a scatterlist before and
after the change.
Hmm, we're missing a pfn-only block I/O user and we're missing the
second half of the implementation that provides __pfn_t_to_page() for
persistent memory. I'm looking to have a solution __pfn_t_to_page()
shortly, maybe that will allow the scatterlist changes to be
skipped... we'll see.
next prev parent reply other threads:[~2015-05-23 16:41 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-12 4:29 [PATCH v3 00/11] evacuate struct page from the block layer, introduce __pfn_t Dan Williams
2015-05-12 4:29 ` Dan Williams
2015-05-12 4:29 ` Dan Williams
2015-05-12 4:29 ` [PATCH v3 01/11] arch: introduce __pfn_t for persistenti/device memory Dan Williams
2015-05-12 4:29 ` Dan Williams
2015-05-12 4:29 ` [PATCH v3 02/11] block: add helpers for accessing a bio_vec page Dan Williams
2015-05-12 4:29 ` Dan Williams
2015-05-12 4:29 ` [PATCH v3 03/11] block: convert .bv_page to .bv_pfn bio_vec Dan Williams
2015-05-12 4:29 ` Dan Williams
2015-05-12 4:29 ` [PATCH v3 04/11] dma-mapping: allow archs to optionally specify a ->map_pfn() operation Dan Williams
2015-05-12 4:29 ` Dan Williams
2015-05-12 4:29 ` [PATCH v3 05/11] scatterlist: use sg_phys() Dan Williams
2015-05-12 4:29 ` Dan Williams
2015-05-12 5:24 ` Julia Lawall
2015-05-12 5:44 ` Dan Williams
2015-05-12 4:30 ` [PATCH v3 06/11] scatterlist: support "page-less" (__pfn_t only) entries Dan Williams
2015-05-12 4:30 ` Dan Williams
2015-05-13 18:35 ` Williams, Dan J
2015-05-13 18:35 ` Williams, Dan J
2015-05-19 4:10 ` Vinod Koul
2015-05-20 16:03 ` Dan Williams
2015-05-23 14:12 ` hch
2015-05-23 14:12 ` hch
2015-05-23 16:41 ` Dan Williams [this message]
2015-05-23 16:41 ` Dan Williams
2015-05-12 4:30 ` [PATCH v3 07/11] x86: support dma_map_pfn() Dan Williams
2015-05-12 4:30 ` Dan Williams
2015-05-12 4:30 ` [PATCH v3 08/11] x86: support kmap_atomic_pfn_t() for persistent memory Dan Williams
2015-05-12 4:30 ` Dan Williams
2015-05-12 4:30 ` [PATCH v3 09/11] block: convert kmap helpers to kmap_atomic_pfn_t() Dan Williams
2015-05-12 4:30 ` Dan Williams
2015-05-12 4:30 ` [PATCH v3 10/11] dax: convert to __pfn_t Dan Williams
2015-05-12 4:30 ` Dan Williams
2015-05-12 4:30 ` [PATCH v3 11/11] block: base support for pfn i/o Dan Williams
2015-05-12 4:30 ` Dan Williams
2015-05-23 14:32 ` [PATCH v3 00/11] evacuate struct page from the block layer, introduce __pfn_t Christoph Hellwig
2015-05-23 14:32 ` Christoph Hellwig
2015-05-23 14:32 ` Christoph Hellwig
2015-05-23 14:32 ` Christoph Hellwig
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