From: Boaz Harrosh <boaz@plexistor.com>
To: ira.weiny@intel.com, linux-kernel@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Dan Williams <dan.j.williams@intel.com>,
Dave Chinner <david@fromorbit.com>,
Christoph Hellwig <hch@lst.de>,
"Theodore Y. Ts'o" <tytso@mit.edu>, Jan Kara <jack@suse.cz>,
linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 1/5] fs/stat: Define DAX statx attribute
Date: Tue, 22 Oct 2019 14:32:04 +0300 [thread overview]
Message-ID: <119b57ed-2799-c499-00df-50da80d23612@plexistor.com> (raw)
In-Reply-To: <20191020155935.12297-2-ira.weiny@intel.com>
On 20/10/2019 18:59, ira.weiny@intel.com wrote:
> From: Ira Weiny <ira.weiny@intel.com>
>
> In order for users to determine if a file is currently operating in DAX
> mode (effective DAX). Define a statx attribute value and set that
> attribute if the effective DAX flag is set.
>
> To go along with this we propose the following addition to the statx man
> page:
>
> STATX_ATTR_DAX
>
> DAX (cpu direct access) is a file mode that attempts to minimize
> software cache effects for both I/O and memory mappings of this
> file. It requires a capable device, a compatible filesystem
> block size, and filesystem opt-in. It generally assumes all
> accesses are via cpu load / store instructions which can
> minimize overhead for small accesses, but adversely affect cpu
> utilization for large transfers. File I/O is done directly
> to/from user-space buffers. While the DAX property tends to
> result in data being transferred synchronously it does not give
> the guarantees of synchronous I/O that data and necessary
> metadata are transferred. Memory mapped I/O may be performed
> with direct mappings that bypass system memory buffering. Again
> while memory-mapped I/O tends to result in data being
> transferred synchronously it does not guarantee synchronous
> metadata updates. A dax file may optionally support being mapped
> with the MAP_SYNC flag which does allow cpu store operations to
> be considered synchronous modulo cpu cache effects.
>
> Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> ---
> fs/stat.c | 3 +++
> include/uapi/linux/stat.h | 1 +
> 2 files changed, 4 insertions(+)
>
> diff --git a/fs/stat.c b/fs/stat.c
> index c38e4c2e1221..59ca360c1ffb 100644
> --- a/fs/stat.c
> +++ b/fs/stat.c
> @@ -77,6 +77,9 @@ int vfs_getattr_nosec(const struct path *path, struct kstat *stat,
> if (IS_AUTOMOUNT(inode))
> stat->attributes |= STATX_ATTR_AUTOMOUNT;
>
> + if (inode->i_flags & S_DAX)
Is there a reason not to use IS_DAX(inode) ?
> + stat->attributes |= STATX_ATTR_DAX;
> +
> if (inode->i_op->getattr)
> return inode->i_op->getattr(path, stat, request_mask,
> query_flags);
> diff --git a/include/uapi/linux/stat.h b/include/uapi/linux/stat.h
> index 7b35e98d3c58..5b0962121ef7 100644
> --- a/include/uapi/linux/stat.h
> +++ b/include/uapi/linux/stat.h
> @@ -169,6 +169,7 @@ struct statx {
> #define STATX_ATTR_ENCRYPTED 0x00000800 /* [I] File requires key to decrypt in fs */
>
> #define STATX_ATTR_AUTOMOUNT 0x00001000 /* Dir: Automount trigger */
> +#define STATX_ATTR_DAX 0x00002000 /* [I] File is DAX */
>
>
> #endif /* _UAPI_LINUX_STAT_H */
>
next prev parent reply other threads:[~2019-10-22 11:32 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-20 15:59 [PATCH 0/5] Enable per-file/directory DAX operations ira.weiny
2019-10-20 15:59 ` [PATCH 1/5] fs/stat: Define DAX statx attribute ira.weiny
2019-10-22 11:32 ` Boaz Harrosh [this message]
2019-10-22 16:51 ` Ira Weiny
2019-10-20 15:59 ` [PATCH 2/5] fs/xfs: Isolate the physical DAX flag from effective ira.weiny
2019-10-21 0:26 ` Dave Chinner
2019-10-21 17:40 ` Ira Weiny
2019-10-20 15:59 ` [PATCH 3/5] fs/xfs: Separate functionality of xfs_inode_supports_dax() ira.weiny
2019-10-20 15:59 ` [PATCH 4/5] fs/xfs: Clean up DAX support check ira.weiny
2019-10-20 15:59 ` [PATCH 5/5] fs/xfs: Allow toggle of physical DAX flag ira.weiny
2019-10-21 0:45 ` Dave Chinner
2019-10-21 22:49 ` Ira Weiny
2019-10-21 23:46 ` Dave Chinner
2019-11-08 13:12 ` Jan Kara
2019-11-08 13:46 ` Jan Kara
2019-11-08 19:36 ` Ira Weiny
2019-11-11 16:07 ` Jan Kara
2019-11-11 23:54 ` Ira Weiny
2019-10-22 11:21 ` [PATCH 0/5] Enable per-file/directory DAX operations Boaz Harrosh
2019-10-23 13:09 ` Boaz Harrosh
2019-10-23 22:13 ` Dave Chinner
2019-10-24 2:31 ` Boaz Harrosh
2019-10-24 7:34 ` Dave Chinner
2019-10-24 14:05 ` Boaz Harrosh
2019-10-24 21:35 ` Dave Chinner
2019-10-24 23:29 ` Boaz Harrosh
2019-10-25 0:36 ` Dave Chinner
2019-10-25 1:15 ` Boaz Harrosh
2019-10-25 20:49 ` Ira Weiny
2019-10-27 22:10 ` Dave Chinner
2019-10-31 16:17 ` Ira Weiny
2019-11-01 22:47 ` Dave Chinner
2019-11-02 4:25 ` Dan Williams
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