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Message-ID: <20200602235305.GI1505637@iweiny-DESK2.sc.intel.com>
Date: Tue, 2 Jun 2020 16:53:05 -0700
From: Ira Weiny <ira.weiny@...el.com>
To: "Darrick J. Wong" <djwong@...nel.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
linux-fsdevel@...r.kernel.org, linux-xfs@...r.kernel.org,
david@...morbit.com, linux-kernel@...r.kernel.org,
sandeen@...deen.net, hch@....de,
linux-ext4 <linux-ext4@...r.kernel.org>,
Theodore Ts'o <tytso@....edu>
Subject: Re: [GIT PULL] vfs: improve DAX behavior for 5.8, part 1
On Tue, Jun 02, 2020 at 09:58:52AM -0700, Darrick J. Wong wrote:
> Hi Linus,
>
> After many years of LKML-wrangling about how to enable programs to query
> and influence the file data access mode (DAX) when a filesystem resides
> on storage devices such as persistent memory, Ira Weiny has emerged with
> a proposed set of standard behaviors that has not been shot down by
> anyone! We're more or less standardizing on the current XFS behavior
> and adapting ext4 to do the same.
Also, for those interested: The corresponding man page change mentioned in the
commit has been submitted here:
https://lore.kernel.org/lkml/20200505002016.1085071-1-ira.weiny@intel.com/
Ira
>
> This pull request is the first of a handful that will make ext4 and XFS
> present a consistent interface for user programs that care about DAX.
> We add a statx attribute that programs can check to see if DAX is
> enabled on a particular file. Then, we update the DAX documentation to
> spell out the user-visible behaviors that filesystems will guarantee
> (until the next storage industry shakeup). The on-disk inode flag has
> been in XFS for a few years now.
>
> Note that Stephen Rothwell reported a minor merge conflict[1] between
> the first cleanup patch and a different change in the block layer. The
> resolution looks pretty straightforward, but let me know if you
> encounter problems.
>
> --D
>
> [1] https://lore.kernel.org/linux-next/20200522145848.38cdcf54@canb.auug.org.au/
>
> The following changes since commit 0e698dfa282211e414076f9dc7e83c1c288314fd:
>
> Linux 5.7-rc4 (2020-05-03 14:56:04 -0700)
>
> are available in the Git repository at:
>
> git://git.kernel.org/pub/scm/fs/xfs/xfs-linux.git tags/vfs-5.8-merge-1
>
> for you to fetch changes up to 83d9088659e8f113741bb197324bd9554d159657:
>
> Documentation/dax: Update Usage section (2020-05-04 08:49:39 -0700)
>
> ----------------------------------------------------------------
> New code for 5.8:
> - Clean up io_is_direct.
> - Add a new statx flag to indicate when file data access is being done
> via DAX (as opposed to the page cache).
> - Update the documentation for how system administrators and application
> programmers can take advantage of the (still experimental DAX) feature.
>
> ----------------------------------------------------------------
> Ira Weiny (3):
> fs: Remove unneeded IS_DAX() check in io_is_direct()
> fs/stat: Define DAX statx attribute
> Documentation/dax: Update Usage section
>
> Documentation/filesystems/dax.txt | 142 +++++++++++++++++++++++++++++++++++++-
> drivers/block/loop.c | 6 +-
> fs/stat.c | 3 +
> include/linux/fs.h | 7 +-
> include/uapi/linux/stat.h | 1 +
> 5 files changed, 147 insertions(+), 12 deletions(-)
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