From: Ira Weiny <ira.weiny@intel.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>,
linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org,
Jan Kara <jack@suse.cz>, Dan Williams <dan.j.williams@intel.com>,
Dave Chinner <david@fromorbit.com>,
Christoph Hellwig <hch@lst.de>,
"Theodore Y. Ts'o" <tytso@mit.edu>,
Jeff Moyer <jmoyer@redhat.com>,
linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH V9 09/11] fs: Introduce DCACHE_DONTCACHE
Date: Tue, 21 Apr 2020 20:46:09 -0700 [thread overview]
Message-ID: <20200422034609.GH3372712@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20200422023407.GH23230@ZenIV.linux.org.uk>
On Wed, Apr 22, 2020 at 03:34:07AM +0100, Al Viro wrote:
> On Tue, Apr 21, 2020 at 01:25:19PM -0700, Darrick J. Wong wrote:
>
> > > DCACHE_DONTCACHE indicates a dentry should not be cached on final
> > > dput().
> > >
> > > Also add a helper function to mark DCACHE_DONTCACHE on all dentries
> > > pointing to a specific inode when that inode is being set I_DONTCACHE.
> > >
> > > This facilitates dropping dentry references to inodes sooner which
> > > require eviction to swap S_DAX mode.
>
> Explain, please. Questions:
>
> 1) does that ever happen to directories?
Directories never get S_DAX set. So the eviction only needs to happen on
inodes. But that can't happen without dentries also dropping their references.
> 2) how much trouble do we get if such inode is *NOT* evicted for, say, several
> days?
No trouble at all. Users understand that changing the FS_XFLAG_DAX setting
does _not_ immediately result in S_DAX changing.
It is intended that applications requiring a change of mode would flip the
FS_XFLAG_DAX close the file and wait for the eviction (or force it through a
drop cache if they have permission).
Ira
next prev parent reply other threads:[~2020-04-22 3:46 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-21 19:17 [PATCH V9 00/11] XFS - Enable per-file/per-directory DAX operations V9 ira.weiny
2020-04-21 19:17 ` [PATCH V9 01/11] fs/xfs: Remove unnecessary initialization of i_rwsem ira.weiny
2020-04-21 19:17 ` [PATCH V9 02/11] fs: Remove unneeded IS_DAX() check in io_is_direct() ira.weiny
2020-04-21 20:13 ` Darrick J. Wong
2020-04-22 8:37 ` Jan Kara
2020-04-21 19:17 ` [PATCH V9 03/11] fs/stat: Define DAX statx attribute ira.weiny
2020-04-22 16:29 ` Darrick J. Wong
2020-04-22 18:51 ` Ira Weiny
2020-04-23 8:24 ` Jan Kara
2020-04-21 19:17 ` [PATCH V9 04/11] fs/xfs: Change XFS_MOUNT_DAX to XFS_MOUNT_DAX_ALWAYS ira.weiny
2020-04-21 19:17 ` [PATCH V9 05/11] fs/xfs: Make DAX mount option a tri-state ira.weiny
2020-04-21 20:16 ` Darrick J. Wong
2020-04-21 21:06 ` Ira Weiny
2020-04-21 19:17 ` [PATCH V9 06/11] fs/xfs: Create function xfs_inode_should_enable_dax() ira.weiny
2020-04-21 19:17 ` [PATCH V9 07/11] fs/xfs: Combine xfs_diflags_to_linux() and xfs_diflags_to_iflags() ira.weiny
2020-04-21 19:17 ` [PATCH V9 08/11] fs: Lift XFS_IDONTCACNE to the VFS layer ira.weiny
2020-04-21 20:23 ` Darrick J. Wong
2020-04-21 21:12 ` Ira Weiny
2020-04-22 8:41 ` Jan Kara
2020-04-21 19:17 ` [PATCH V9 09/11] fs: Introduce DCACHE_DONTCACHE ira.weiny
2020-04-21 20:25 ` Darrick J. Wong
2020-04-21 21:15 ` Ira Weiny
2020-04-22 2:34 ` Al Viro
2020-04-22 3:46 ` Ira Weiny [this message]
2020-04-22 8:46 ` Jan Kara
2020-04-22 15:19 ` Ira Weiny
2020-04-21 19:17 ` [PATCH V9 10/11] fs/xfs: Update xfs_ioctl_setattr_dax_invalidate() ira.weiny
2020-04-21 20:31 ` Darrick J. Wong
2020-04-21 21:30 ` Dave Chinner
2020-04-21 21:43 ` Ira Weiny
2020-04-21 23:13 ` Dave Chinner
2020-04-21 23:24 ` Ira Weiny
2020-04-21 19:17 ` [PATCH V9 11/11] Documentation/dax: Update Usage section ira.weiny
2020-04-21 20:34 ` Darrick J. Wong
2020-04-21 21:49 ` Ira Weiny
2020-04-22 9:47 ` Jan Kara
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