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Date:   Tue, 21 Apr 2020 11:31:21 -0700
From:   "Darrick J. Wong" <darrick.wong@oracle.com>
To:     Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc:     Linux Doc Mailing List <linux-doc@vger.kernel.org>,
        linux-kernel@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
        Jan Kara <jack@suse.com>, linux-ext4@vger.kernel.org,
        ira.weiny@intel.com
Subject: Re: [PATCH 12/34] docs: filesystems: convert dax.txt to ReST
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On Tue, Apr 21, 2020 at 06:31:17PM +0200, Mauro Carvalho Chehab wrote:
> Em Wed, 15 Apr 2020 08:41:44 -0700
> "Darrick J. Wong" <darrick.wong@oracle.com> escreveu:
> 
> > [add ira weiny to cc]
> > 
> > On Wed, Apr 15, 2020 at 04:32:25PM +0200, Mauro Carvalho Chehab wrote:
> > > - Add a SPDX header;
> > > - Adjust document title;
> > > - Some whitespace fixes and new line breaks;
> > > - Add it to filesystems/index.rst.
> > > 
> > > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> > > ---
> > >  Documentation/admin-guide/ext4.rst             | 2 +-
> > >  Documentation/filesystems/{dax.txt => dax.rst} | 9 +++++++--
> > >  Documentation/filesystems/ext2.rst             | 2 +-
> > >  Documentation/filesystems/index.rst            | 1 +
> > >  4 files changed, 10 insertions(+), 4 deletions(-)
> > >  rename Documentation/filesystems/{dax.txt => dax.rst} (97%)
> > > 
> > > diff --git a/Documentation/admin-guide/ext4.rst b/Documentation/admin-guide/ext4.rst
> > > index 9443fcef1876..103bcc345bad 100644
> > > --- a/Documentation/admin-guide/ext4.rst
> > > +++ b/Documentation/admin-guide/ext4.rst
> > > @@ -392,7 +392,7 @@ When mounting an ext4 filesystem, the following option are accepted:
> > >  
> > >    dax
> > >          Use direct access (no page cache).  See
> > > -        Documentation/filesystems/dax.txt.  Note that this option is
> > > +        Documentation/filesystems/dax.rst.  Note that this option is
> > >          incompatible with data=journal.
> > >  
> > >  Data Mode
> > > diff --git a/Documentation/filesystems/dax.txt b/Documentation/filesystems/dax.rst
> > > similarity index 97%
> > > rename from Documentation/filesystems/dax.txt
> > > rename to Documentation/filesystems/dax.rst
> > > index 735f3859b19f..5838144f80f0 100644
> > > --- a/Documentation/filesystems/dax.txt
> > > +++ b/Documentation/filesystems/dax.rst  
> > 
> > Err, this will collide with the work that Ira's doing on DAX for 5.8[1].
> > Can the dax.txt conversion wait?
> 
> Well, I can re-schedule it to 5.9. Or, if you merge the dax changes
> at linux-next, I can rebase my patch on the top of it.

That depends on how quick Ira can get the series merged. :)

I personally think (hope) everyone's tired of arguing and we can just
get it done for 5.8, but past experience tells me that rescheduling the
rst conversion to 5.90 is at least a safer bet.

--D

> > 
> > --D
> > 
> > [1] https://lore.kernel.org/linux-xfs/20200415152942.GS6742@magnolia/T/#m804562299416d865d8829caa82589a522b2080a5
> > 
> > > @@ -1,5 +1,8 @@
> > > +.. SPDX-License-Identifier: GPL-2.0
> > > +
> > > +=======================
> > >  Direct Access for files
> > > ------------------------
> > > +=======================
> > >  
> > >  Motivation
> > >  ----------
> > > @@ -46,6 +49,7 @@ stall the CPU for an extended period, you should also not attempt to
> > >  implement direct_access.
> > >  
> > >  These block devices may be used for inspiration:
> > > +
> > >  - brd: RAM backed block device driver
> > >  - dcssblk: s390 dcss block device driver
> > >  - pmem: NVDIMM persistent memory driver
> > > @@ -55,6 +59,7 @@ Implementation Tips for Filesystem Writers
> > >  ------------------------------------------
> > >  
> > >  Filesystem support consists of
> > > +
> > >  - adding support to mark inodes as being DAX by setting the S_DAX flag in
> > >    i_flags
> > >  - implementing ->read_iter and ->write_iter operations which use dax_iomap_rw()
> > > @@ -127,6 +132,6 @@ by adding optional struct page support for pages under the control of
> > >  the driver (see CONFIG_NVDIMM_PFN in drivers/nvdimm for an example of
> > >  how to do this). In the non struct page cases O_DIRECT reads/writes to
> > >  those memory ranges from a non-DAX file will fail (note that O_DIRECT
> > > -reads/writes _of a DAX file_ do work, it is the memory that is being
> > > +reads/writes _of a DAX ``file_`` do work, it is the memory that is being
> > >  accessed that is key here).  Other things that will not work in the
> > >  non struct page case include RDMA, sendfile() and splice().
> > > diff --git a/Documentation/filesystems/ext2.rst b/Documentation/filesystems/ext2.rst
> > > index d83dbbb162e2..fa416b7a5802 100644
> > > --- a/Documentation/filesystems/ext2.rst
> > > +++ b/Documentation/filesystems/ext2.rst
> > > @@ -24,7 +24,7 @@ check=none, nocheck	(*)	Don't do extra checking of bitmaps on mount
> > >  				(check=normal and check=strict options removed)
> > >  
> > >  dax				Use direct access (no page cache).  See
> > > -				Documentation/filesystems/dax.txt.
> > > +				Documentation/filesystems/dax.rst.
> > >  
> > >  debug				Extra debugging information is sent to the
> > >  				kernel syslog.  Useful for developers.
> > > diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst
> > > index c4f95f76ba6a..8e3ccb4ed483 100644
> > > --- a/Documentation/filesystems/index.rst
> > > +++ b/Documentation/filesystems/index.rst
> > > @@ -24,6 +24,7 @@ algorithms work.
> > >     splice
> > >     locking
> > >     directory-locking
> > > +   dax
> > >  
> > >     automount-support
> > >  
> > > -- 
> > > 2.25.2
> > >   
> 
> 
> 
> Thanks,
> Mauro