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Description of problem:
From the kernel kernel-4.18.0-250.el8.dt1, STATX_ATTR_DAX is supported. But the statx man pages doesn't include this. Please add it.
kernel patch:
"
commit 72c01f0f9720697fcb9430c3fb7dd80383544a3e
Author: Eric Sandeen <sandeen>
Date: Thu Oct 29 17:39:01 2020 -0400
[fs] fs/stat: Define DAX statx attribute
Message-id: <20201029173930.11735-26-sandeen>
Patchwork-id: 336294
Patchwork-instance: patchwork
O-Subject: [RHEL8 PATCH V2 25/54] fs/stat: Define DAX statx attribute
Bugzilla: 1838876 1854346 1838344
RH-Acked-by: Jeff Moyer <jmoyer>
RH-Acked-by: Carlos Maiolino <cmaiolino>
From: Ira Weiny <ira.weiny>
In order for users to determine if a file is currently operating in DAX
state (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
The file is in the DAX (cpu direct access) state. DAX state
attempts to minimize software cache effects for both I/O and
memory mappings of this file. It requires a file system which
has been configured to support DAX.
DAX generally assumes all accesses are via cpu load / store
instructions which can minimize overhead for small accesses, but
may adversely affect cpu utilization for large transfers.
File I/O is done directly to/from user-space buffers and memory
mapped I/O may be performed with direct memory mappings that
bypass kernel page cache.
While the DAX property tends to result in data being transferred
synchronously, it does not give the same guarantees of O_SYNC
where data and the necessary metadata are transferred together.
A DAX file may support being mapped with the MAP_SYNC flag,
which enables a program to use CPU cache flush instructions to
persist CPU store operations without an explicit fsync(2). See
mmap(2) for more information.
"
https://man7.org/linux/man-pages/man2/statx.2.html
Version-Release number of selected component (if applicable):
man-pages-4.15-6.el8.x86_64
How reproducible:
100%
Steps to Reproduce:
1. man statx
2.
3.
Actual results:
There is no info for STATX_ATTR_DAX in statx man pages
Expected results:
Add STATX_ATTR_DAX info in statx man pages
Additional info:
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory (man-pages-overrides bug fix and enhancement update), and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2021:4293
Description of problem: From the kernel kernel-4.18.0-250.el8.dt1, STATX_ATTR_DAX is supported. But the statx man pages doesn't include this. Please add it. kernel patch: " commit 72c01f0f9720697fcb9430c3fb7dd80383544a3e Author: Eric Sandeen <sandeen> Date: Thu Oct 29 17:39:01 2020 -0400 [fs] fs/stat: Define DAX statx attribute Message-id: <20201029173930.11735-26-sandeen> Patchwork-id: 336294 Patchwork-instance: patchwork O-Subject: [RHEL8 PATCH V2 25/54] fs/stat: Define DAX statx attribute Bugzilla: 1838876 1854346 1838344 RH-Acked-by: Jeff Moyer <jmoyer> RH-Acked-by: Carlos Maiolino <cmaiolino> From: Ira Weiny <ira.weiny> In order for users to determine if a file is currently operating in DAX state (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 The file is in the DAX (cpu direct access) state. DAX state attempts to minimize software cache effects for both I/O and memory mappings of this file. It requires a file system which has been configured to support DAX. DAX generally assumes all accesses are via cpu load / store instructions which can minimize overhead for small accesses, but may adversely affect cpu utilization for large transfers. File I/O is done directly to/from user-space buffers and memory mapped I/O may be performed with direct memory mappings that bypass kernel page cache. While the DAX property tends to result in data being transferred synchronously, it does not give the same guarantees of O_SYNC where data and the necessary metadata are transferred together. A DAX file may support being mapped with the MAP_SYNC flag, which enables a program to use CPU cache flush instructions to persist CPU store operations without an explicit fsync(2). See mmap(2) for more information. " https://man7.org/linux/man-pages/man2/statx.2.html Version-Release number of selected component (if applicable): man-pages-4.15-6.el8.x86_64 How reproducible: 100% Steps to Reproduce: 1. man statx 2. 3. Actual results: There is no info for STATX_ATTR_DAX in statx man pages Expected results: Add STATX_ATTR_DAX info in statx man pages Additional info: