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Bug 2226900 - mkfs.xfs(8): Update section on dax+reflink compatibility
Summary: mkfs.xfs(8): Update section on dax+reflink compatibility
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: xfsprogs
Version: 9.3
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Pavel Reichl
QA Contact: xiaoli feng
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2023-07-26 21:46 UTC by Eric Sandeen
Modified: 2023-11-07 11:24 UTC (History)
5 users (show)

Fixed In Version: xfsprogs-5.19.0-4.el9
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2023-11-07 08:52:46 UTC
Type: Bug
Target Upstream Version:
Embargoed:
pm-rhel: mirror+

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker RHELPLAN-163611 0 None None None 2023-07-26 21:49:49 UTC
Red Hat Product Errata RHBA-2023:6618 0 None None None 2023-11-07 08:52:51 UTC

Description Eric Sandeen 2023-07-26 21:46:38 UTC 
The current version of the mkfs.xfs man page in RHEL9 (and upstream) contains this caveat:

> Note: the filesystem DAX mount option ( -o dax ) is incompatible with reflink-enabled XFS filesystems.  To use  filesystem DAX with XFS, specify the -m reflink=0 option to mkfs.xfs to disable the reflink feature.

This is no longer the case upstream, and with the updates in kernel bug #2192730 it is no longer the case for RHEL9.

We need to send a patch upstream to address this, probably mentioning the kernel version which added dax+reflink support, and add a similar patch to RHEL9.

Thanks,
-Eric
Comment 1 Eric Sandeen 2023-08-01 01:01:42 UTC 
The patch to fix this upstream has been sent to the xfs mailing list, and was reviewed by Darrick.

Carlos, if you approve of the change as well, getting it to for-next would be a good next step so that we can backport it to RHEL9.3 fairly soon.

Thanks,
-Eric
Comment 5 Bill O'Donnell 2023-08-02 13:33:09 UTC 
Yes, please!
Comment 6 Pavel Reichl 2023-08-02 14:09:20 UTC 
Back porting: 780e93c5 mkfs.xfs.8: correction on mkfs.xfs manpage since reflink and dax are compatible
Comment 9 xiaoli feng 2023-08-04 04:59:19 UTC 
Find this info in mkfs.xfs of xfsprogs-5.19.0-3.el9.x86_64.
[root@dell-per750-43 xfstests-dev]# rpm -qa xfsprogs
xfsprogs-5.19.0-3.el9.x86_64
[root@dell-per750-43 ~]# man mkfs.xfs |grep -A 2 -i dax
                          Note:  the  filesystem  DAX mount option ( -o dax ) is incompatible with reflink-enabled XFS filesystems.  To use filesystem DAX
                          with XFS, specify the -m reflink=0 option to mkfs.xfs to disable the reflink feature.

--
                   daxinherit=value
                          If value is set to 1, all inodes created by mkfs.xfs will be created with the DAX flag set.  The default is 0.  Directories will
                          pass on this flag to newly created regular files and directories.  By default, mkfs.xfs will not enable DAX mode.

       -f     Force overwrite when an existing filesystem is detected on the device.  By default, mkfs.xfs will not write to the  device  if  it  suspects



Verify on xfsprogs-5.19.0-4.el9
[root@dell-per750-43 ~]# man mkfs.xfs |grep -A 2 -i dax
                   daxinherit=value
                          If value is set to 1, all inodes created by mkfs.xfs will be created with the DAX flag set.  The default is 0.  Directories will
                          pass on this flag to newly created regular files and directories.  By default, mkfs.xfs will not enable DAX mode.

       -f     Force  overwrite  when  an  existing filesystem is detected on the device.  By default, mkfs.xfs will not write to the device if it suspects
[root@dell-per750-43 ~]# rpm -qa xfsprogs
xfsprogs-5.19.0-4.el9.x86_64
Comment 14 errata-xmlrpc 2023-11-07 08:52:46 UTC 
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 (xfsprogs 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-2023:6618
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