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Date: Sun, 20 Oct 2019 08:59:30 -0700 From: ira.weiny@...el.com To: linux-kernel@...r.kernel.org Cc: Ira Weiny <ira.weiny@...el.com>, Alexander Viro <viro@...iv.linux.org.uk>, "Darrick J. Wong" <darrick.wong@...cle.com>, Dan Williams <dan.j.williams@...el.com>, Dave Chinner <david@...morbit.com>, Christoph Hellwig <hch@....de>, "Theodore Y. Ts'o" <tytso@....edu>, Jan Kara <jack@...e.cz>, linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org Subject: [PATCH 0/5] Enable per-file/directory DAX operations From: Ira Weiny <ira.weiny@...el.com> At LSF/MM'19 [1] [2] we discussed applications that overestimate memory consumption due to their inability to detect whether the kernel will instantiate page cache for a file, and cases where a global dax enable via a mount option is too coarse. The following patch series enables selecting the use of DAX on individual files and/or directories on xfs, and lays some groundwork to do so in ext4. In this scheme the dax mount option can be omitted to allow the per-file property to take effect. The insight at LSF/MM was to separate the per-mount or per-file "physical" capability switch from an "effective" attribute for the file. At LSF/MM we discussed the difficulties of switching the mode of a file with active mappings / page cache. Rather than solve those races the decision was to just limit mode flips to 0-length files. Finally, the physical DAX flag inheritance is maintained from previous work on XFS but should be added for other file systems for consistence. [1] https://lwn.net/Articles/787973/ [2] https://lwn.net/Articles/787233/ To: linux-kernel@...r.kernel.org Cc: Alexander Viro <viro@...iv.linux.org.uk> Cc: "Darrick J. Wong" <darrick.wong@...cle.com> Cc: Dan Williams <dan.j.williams@...el.com> Cc: Dave Chinner <david@...morbit.com> Cc: Christoph Hellwig <hch@....de> Cc: "Theodore Y. Ts'o" <tytso@....edu> Cc: Jan Kara <jack@...e.cz> Cc: linux-ext4@...r.kernel.org Cc: linux-xfs@...r.kernel.org Cc: linux-fsdevel@...r.kernel.org Ira Weiny (5): fs/stat: Define DAX statx attribute fs/xfs: Isolate the physical DAX flag from effective fs/xfs: Separate functionality of xfs_inode_supports_dax() fs/xfs: Clean up DAX support check fs/xfs: Allow toggle of physical DAX flag fs/stat.c | 3 +++ fs/xfs/xfs_ioctl.c | 32 ++++++++++++++------------------ fs/xfs/xfs_iops.c | 36 ++++++++++++++++++++++++++++++------ fs/xfs/xfs_iops.h | 2 ++ include/uapi/linux/stat.h | 1 + 5 files changed, 50 insertions(+), 24 deletions(-) -- 2.20.1
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