From: Dan Williams <dan.j.williams@intel.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Dave Chinner <david@fromorbit.com>,
Miklos Szeredi <miklos@szeredi.hu>,
linux-nvdimm <linux-nvdimm@lists.01.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
virtio-fs@redhat.com, Stefan Hajnoczi <stefanha@redhat.com>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 01/19] dax: remove block device dependencies
Date: Tue, 7 Jan 2020 11:46:37 -0800 [thread overview]
Message-ID: <CAPcyv4ia9r0rdbb7t0JvEnGW6nnHdAWUHbaMrY5FKBY+4Fum6Q@mail.gmail.com> (raw)
In-Reply-To: <20200107190258.GB472665@magnolia>
On Tue, Jan 7, 2020 at 11:03 AM Darrick J. Wong <darrick.wong@oracle.com> wrote:
[..]
> > That can already happen today. If you do not properly align the
> > partition then dax operations will be disabled.
>
> Er... is this conversation getting confused? I was talking about
> kpartx's /dev/mapper/pmem0p1 being a straight replacement for the kernel
> creating /dev/pmem0p1. I thnk Vivek was complaining about the
> inconsistent behavior between the two, even if the partition is aligned
> properly.
>
> I'm not sure how alignment leaked in here?
Oh, whoops, I was jumping to the mismatch between host device and
partition and whether we had precedent to fail to support dax on the
partition when the base block device does support it.
But yes, the mismatch between kpartx and native partitions is weird.
That said kpartx is there to add partition support where the kernel
for whatever reason fails to, or chooses not to, and dax is looking
like such a place.
> > This proposal just
> > extends that existing failure domain to make all partitions fail to
> > support dax.
>
> Oh, wait. You're proposing that "partitions of pmem devices don't
> support DAX", not "the kernel will not create partitions for pmem
> devices".
>
> Yeah, that would be inconsistent and weird.
More weird than the current constraints?
> I'd say deprecate the
> kernel automounting partitions, but I guess it already does that, and
Ok, now I don't know why automounting is leaking into this discussion?
> removing it would break /something/.
Yes, the breakage risk is anyone that was using ext4 mount failure as
a dax capability detector.
> I guess you could put
> "/dev/pmemXpY" on the deprecation schedule.
...but why deprecate /dev/pmemXpY partitions altogether? If someone
doesn't care about dax then they can do all the legacy block things.
If they do care about dax then work with whole device namespaces.
The proposal is to detect dax on partitions and warn people to move to
kpartx. Let the core fs/dax implementation continue to shed block
dependencies.
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next prev parent reply other threads:[~2020-01-07 19:46 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-21 17:57 [PATCH v3 00/19][RFC] virtio-fs: Enable DAX support Vivek Goyal
2019-08-21 17:57 ` [PATCH 01/19] dax: remove block device dependencies Vivek Goyal
2019-08-26 11:51 ` Christoph Hellwig
2019-08-27 16:38 ` Vivek Goyal
2019-08-28 6:58 ` Christoph Hellwig
2019-08-28 17:58 ` Vivek Goyal
2019-08-28 22:53 ` Dave Chinner
2019-08-29 0:04 ` Dan Williams
2019-08-29 9:32 ` Christoph Hellwig
2019-12-16 18:10 ` Vivek Goyal
2020-01-07 12:51 ` Christoph Hellwig
2020-01-07 14:22 ` Dan Williams
2020-01-07 17:07 ` Darrick J. Wong
2020-01-07 17:29 ` Dan Williams
2020-01-07 18:01 ` Vivek Goyal
2020-01-07 18:07 ` Dan Williams
2020-01-07 18:33 ` Vivek Goyal
2020-01-07 18:49 ` Dan Williams
2020-01-07 19:02 ` Darrick J. Wong
2020-01-07 19:46 ` Dan Williams [this message]
2020-01-07 23:38 ` Dan Williams
2020-01-09 11:24 ` Jan Kara
2020-01-09 20:03 ` Dan Williams
2020-01-10 12:36 ` Christoph Hellwig
2020-01-14 20:31 ` Vivek Goyal
2020-01-14 20:39 ` Dan Williams
2020-01-14 21:28 ` Vivek Goyal
2020-01-14 22:23 ` Dan Williams
2020-01-15 19:56 ` Vivek Goyal
2020-01-15 20:17 ` Dan Williams
2020-01-15 21:08 ` Jeff Moyer
2020-01-16 18:09 ` Dan Williams
2020-01-16 18:39 ` Vivek Goyal
2020-01-16 19:09 ` Dan Williams
2020-01-16 19:23 ` Vivek Goyal
2020-02-11 17:33 ` Vivek Goyal
2020-01-15 9:03 ` Jan Kara
2019-08-21 17:57 ` [PATCH 02/19] dax: Pass dax_dev to dax_writeback_mapping_range() Vivek Goyal
2019-08-26 11:53 ` Christoph Hellwig
2019-08-26 20:33 ` Vivek Goyal
2019-08-26 20:58 ` Vivek Goyal
2019-08-26 21:33 ` Dan Williams
2019-08-28 6:58 ` Christoph Hellwig
2020-01-03 14:12 ` Vivek Goyal
2020-01-03 18:12 ` Dan Williams
2020-01-03 18:18 ` Dan Williams
2020-01-03 18:33 ` Vivek Goyal
2020-01-03 19:30 ` Dan Williams
2020-01-03 18:43 ` Vivek Goyal
2019-08-27 13:45 ` Jan Kara
2019-08-21 17:57 ` [PATCH 03/19] virtio: Add get_shm_region method Vivek Goyal
2019-08-21 17:57 ` [PATCH 04/19] virtio: Implement get_shm_region for PCI transport Vivek Goyal
2019-08-26 1:43 ` [Virtio-fs] " piaojun
2019-08-26 13:06 ` Vivek Goyal
2019-08-27 9:41 ` piaojun
2019-08-27 8:34 ` Cornelia Huck
2019-08-27 8:46 ` Cornelia Huck
2019-08-27 11:53 ` Vivek Goyal
2019-08-21 17:57 ` [PATCH 05/19] virtio: Implement get_shm_region for MMIO transport Vivek Goyal
2019-08-27 8:39 ` Cornelia Huck
2019-08-27 11:54 ` Vivek Goyal
2019-08-21 17:57 ` [PATCH 06/19] fuse, dax: add fuse_conn->dax_dev field Vivek Goyal
2019-08-21 17:57 ` [PATCH 07/19] virtio_fs, dax: Set up virtio_fs dax_device Vivek Goyal
2019-08-21 17:57 ` [PATCH 08/19] fuse: Keep a list of free dax memory ranges Vivek Goyal
2019-08-21 17:57 ` [PATCH 09/19] fuse: implement FUSE_INIT map_alignment field Vivek Goyal
2019-08-21 17:57 ` [PATCH 10/19] fuse: Introduce setupmapping/removemapping commands Vivek Goyal
2019-08-21 17:57 ` [PATCH 11/19] fuse, dax: Implement dax read/write operations Vivek Goyal
2019-08-21 19:49 ` Liu Bo
2019-08-22 12:59 ` Vivek Goyal
2019-08-21 17:57 ` [PATCH 12/19] fuse, dax: add DAX mmap support Vivek Goyal
2019-08-21 17:57 ` [PATCH 13/19] fuse: Define dax address space operations Vivek Goyal
2019-08-21 17:57 ` [PATCH 14/19] fuse, dax: Take ->i_mmap_sem lock during dax page fault Vivek Goyal
2019-08-21 17:57 ` [PATCH 15/19] fuse: Maintain a list of busy elements Vivek Goyal
2019-08-21 17:57 ` [PATCH 16/19] dax: Create a range version of dax_layout_busy_page() Vivek Goyal
2019-08-21 17:57 ` [PATCH 17/19] fuse: Add logic to free up a memory range Vivek Goyal
2019-08-21 17:57 ` [PATCH 18/19] fuse: Release file in process context Vivek Goyal
2019-08-21 17:57 ` [PATCH 19/19] fuse: Take inode lock for dax inode truncation Vivek Goyal
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