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From: Vivek Goyal <vgoyal@redhat.com>
To: Amir Goldstein <amir73il@gmail.com>
Cc: linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-nvdimm <linux-nvdimm@lists.01.org>,
	virtio-fs@redhat.com, Miklos Szeredi <miklos@szeredi.hu>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	mst@redhat.com
Subject: Re: [PATCH 00/20] virtiofs: Add DAX support
Date: Wed, 11 Mar 2020 15:39:43 -0400	[thread overview]
Message-ID: <20200311193943.GE83257@redhat.com> (raw)
In-Reply-To: <CAOQ4uxjja3cReO28qOd-YGmhU-_KrLxOCaBeqZYydxPAte9_pg@mail.gmail.com>

On Wed, Mar 11, 2020 at 09:32:17PM +0200, Amir Goldstein wrote:
> On Wed, Mar 11, 2020 at 8:48 PM Vivek Goyal <vgoyal@redhat.com> wrote:
> >
> > On Wed, Mar 11, 2020 at 07:22:51AM +0200, Amir Goldstein wrote:
> > > On Wed, Mar 4, 2020 at 7:01 PM Vivek Goyal <vgoyal@redhat.com> wrote:
> > > >
> > > > Hi,
> > > >
> > > > This patch series adds DAX support to virtiofs filesystem. This allows
> > > > bypassing guest page cache and allows mapping host page cache directly
> > > > in guest address space.
> > > >
> > > > When a page of file is needed, guest sends a request to map that page
> > > > (in host page cache) in qemu address space. Inside guest this is
> > > > a physical memory range controlled by virtiofs device. And guest
> > > > directly maps this physical address range using DAX and hence gets
> > > > access to file data on host.
> > > >
> > > > This can speed up things considerably in many situations. Also this
> > > > can result in substantial memory savings as file data does not have
> > > > to be copied in guest and it is directly accessed from host page
> > > > cache.
> > > >
> > > > Most of the changes are limited to fuse/virtiofs. There are couple
> > > > of changes needed in generic dax infrastructure and couple of changes
> > > > in virtio to be able to access shared memory region.
> > > >
> > > > These patches apply on top of 5.6-rc4 and are also available here.
> > > >
> > > > https://github.com/rhvgoyal/linux/commits/vivek-04-march-2020
> > > >
> > > > Any review or feedback is welcome.
> > > >
> > > [...]
> > > >  drivers/dax/super.c                |    3 +-
> > > >  drivers/virtio/virtio_mmio.c       |   32 +
> > > >  drivers/virtio/virtio_pci_modern.c |  107 +++
> > > >  fs/dax.c                           |   66 +-
> > > >  fs/fuse/dir.c                      |    2 +
> > > >  fs/fuse/file.c                     | 1162 +++++++++++++++++++++++++++-
> > >
> > > That's a big addition to already big file.c.
> > > Maybe split dax specific code to dax.c?
> > > Can be a post series cleanup too.
> >
> > How about fs/fuse/iomap.c instead. This will have all the iomap related logic
> > as well as all the dax range allocation/free logic which is required
> > by iomap logic. That moves about 900 lines of code from file.c to iomap.c
> >
> 
> Fine by me. I didn't take time to study the code in file.c
> I just noticed is has grown a lot bigger and wasn't sure that
> it made sense. Up to you. Only if you think the result would be nicer
> to maintain.

I am happy to move this code to a separate file. In fact I think we could
probably break it further into another file say dax-mapping.c or something
like that where all the memory range allocation/reclaim logic goes and
iomap logic remains in iomap.c.

But that's probably a future cleanup if code in this file continues to grow.

Vivek
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  reply	other threads:[~2020-03-11 19:40 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-04 16:58 Vivek Goyal
2020-03-04 16:58 ` [PATCH 01/20] dax: Modify bdev_dax_pgoff() to handle NULL bdev Vivek Goyal
2020-03-04 16:58 ` [PATCH 02/20] dax: Create a range version of dax_layout_busy_page() Vivek Goyal
2020-03-10 15:19   ` Ira Weiny
2020-03-10 20:29     ` Vivek Goyal
2020-03-04 16:58 ` [PATCH 03/20] virtio: Add get_shm_region method Vivek Goyal
2020-03-10 10:53   ` Stefan Hajnoczi
2020-03-04 16:58 ` [PATCH 04/20] virtio: Implement get_shm_region for PCI transport Vivek Goyal
2020-03-10 11:04   ` Stefan Hajnoczi
2020-03-10 18:19     ` Vivek Goyal
2020-03-11 17:34       ` Stefan Hajnoczi
2020-03-11 19:29         ` Vivek Goyal
2020-03-10 11:12   ` Michael S. Tsirkin
2020-03-10 18:47     ` Vivek Goyal
2020-03-10 21:27       ` Michael S. Tsirkin
2020-03-04 16:58 ` [PATCH 05/20] virtio: Implement get_shm_region for MMIO transport Vivek Goyal
2020-03-10 11:06   ` Stefan Hajnoczi
2020-03-04 16:58 ` [PATCH 06/20] virtiofs: Provide a helper function for virtqueue initialization Vivek Goyal
2020-03-10 14:10   ` Miklos Szeredi
2020-03-04 16:58 ` [PATCH 07/20] fuse: Get rid of no_mount_options Vivek Goyal
2020-03-10 14:12   ` Miklos Szeredi
2020-03-04 16:58 ` [PATCH 08/20] fuse,virtiofs: Add a mount option to enable dax Vivek Goyal
2020-03-10 14:16   ` Miklos Szeredi
2020-03-04 16:58 ` [PATCH 09/20] virtio_fs, dax: Set up virtio_fs dax_device Vivek Goyal
2020-03-04 16:58 ` [PATCH 10/20] fuse,virtiofs: Keep a list of free dax memory ranges Vivek Goyal
2020-03-10 19:29   ` Miklos Szeredi
2020-03-04 16:58 ` [PATCH 11/20] fuse: implement FUSE_INIT map_alignment field Vivek Goyal
2020-03-10 19:31   ` Miklos Szeredi
2020-03-04 16:58 ` [PATCH 12/20] fuse: Introduce setupmapping/removemapping commands Vivek Goyal
2020-03-10 19:49   ` Miklos Szeredi
2020-03-10 20:33     ` Vivek Goyal
2020-03-11  7:03       ` Amir Goldstein
2020-03-11 14:19         ` Miklos Szeredi
2020-03-11 14:41           ` Vivek Goyal
2020-03-11 15:12             ` Miklos Szeredi
2020-03-04 16:58 ` [PATCH 13/20] fuse, dax: Implement dax read/write operations Vivek Goyal
2020-03-12  9:43   ` Miklos Szeredi
2020-03-12 16:02     ` Vivek Goyal
2020-03-13 10:18       ` Miklos Szeredi
2020-03-13 13:41         ` Vivek Goyal
2020-04-04  0:25   ` Liu Bo
2020-04-14 12:54     ` Vivek Goyal
2020-03-04 16:58 ` [PATCH 14/20] fuse,dax: add DAX mmap support Vivek Goyal
2020-03-04 16:58 ` [PATCH 15/20] fuse, dax: Take ->i_mmap_sem lock during dax page fault Vivek Goyal
2020-03-04 16:58 ` [PATCH 16/20] fuse,virtiofs: Define dax address space operations Vivek Goyal
2020-03-04 16:58 ` [PATCH 17/20] fuse,virtiofs: Maintain a list of busy elements Vivek Goyal
2020-03-04 16:58 ` [PATCH 18/20] fuse: Release file in process context Vivek Goyal
2020-03-04 16:58 ` [PATCH 19/20] fuse: Take inode lock for dax inode truncation Vivek Goyal
2020-03-04 16:58 ` [PATCH 20/20] fuse,virtiofs: Add logic to free up a memory range Vivek Goyal
2020-03-11  5:16   ` Liu Bo
2020-03-11 12:59     ` Vivek Goyal
2020-03-11 17:24       ` Liu Bo
2020-03-26  0:09   ` Liu Bo
2020-03-27 14:01     ` Vivek Goyal
2020-03-27 22:06       ` Liu Bo
2020-04-14 19:30         ` Vivek Goyal
2020-04-15 17:22           ` Liu Bo
2020-04-16 19:05             ` Vivek Goyal
2020-04-17 18:05               ` Liu Bo
2020-03-11  5:22 ` [PATCH 00/20] virtiofs: Add DAX support Amir Goldstein
2020-03-11 13:09   ` Vivek Goyal
2020-03-11 18:48   ` Vivek Goyal
2020-03-11 19:32     ` Amir Goldstein
2020-03-11 19:39       ` Vivek Goyal [this message]
2020-03-11 13:38 ` Patrick Ohly
2020-03-16 13:02   ` Vivek Goyal
2020-03-17  8:28     ` Patrick Ohly

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