* [PATCH] mkfs.xfs.8: clarify DAX-vs-reflink restrictions in the mkfs.xfs man page
@ 2021-08-27 15:39 Eric Sandeen
2021-08-27 15:46 ` Bill O'Donnell
2021-08-27 15:49 ` Darrick J. Wong
0 siblings, 2 replies; 5+ messages in thread
From: Eric Sandeen @ 2021-08-27 15:39 UTC (permalink / raw)
To: xfs; +Cc: Bill O'Donnell
Now that we have the tristate dax mount options, it is possible
to enable DAX mode for non-reflinked files on a reflink-capable
filesystem. Clarify this in the mkfs.xfs manpage.
Reported-by: Bill O'Donnell <bodonnel@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---
diff --git a/man/man8/mkfs.xfs.8 b/man/man8/mkfs.xfs.8
index a7f70285..84ac50e8 100644
--- a/man/man8/mkfs.xfs.8
+++ b/man/man8/mkfs.xfs.8
@@ -316,12 +316,20 @@ option set. When the option
is used, the reference count btree feature is not supported and reflink is
disabled.
.IP
-Note: the filesystem DAX mount option (
+Note: the filesystem-wide DAX mount options (
.B \-o dax
-) is incompatible with
-reflink-enabled XFS filesystems. To use filesystem DAX with XFS, specify the
+and
+.B \-o dax=always
+) are incompatible with
+reflink-enabled XFS filesystems. To use filesystem-wide DAX with XFS, specify the
.B \-m reflink=0
option to mkfs.xfs to disable the reflink feature.
+Alternatey, use the
+.B \-o dax=inode
+mount option to selectively enable DAX mode on non-reflinked files.
+See
+.BR xfs (5)
+for more information.
.RE
.PP
.PD 0
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] mkfs.xfs.8: clarify DAX-vs-reflink restrictions in the mkfs.xfs man page
2021-08-27 15:39 [PATCH] mkfs.xfs.8: clarify DAX-vs-reflink restrictions in the mkfs.xfs man page Eric Sandeen
@ 2021-08-27 15:46 ` Bill O'Donnell
2021-08-27 15:47 ` Eric Sandeen
2021-08-27 15:49 ` Darrick J. Wong
1 sibling, 1 reply; 5+ messages in thread
From: Bill O'Donnell @ 2021-08-27 15:46 UTC (permalink / raw)
To: Eric Sandeen; +Cc: xfs, Bill O'Donnell
On Fri, Aug 27, 2021 at 10:39:18AM -0500, Eric Sandeen wrote:
> Now that we have the tristate dax mount options, it is possible
> to enable DAX mode for non-reflinked files on a reflink-capable
> filesystem. Clarify this in the mkfs.xfs manpage.
>
> Reported-by: Bill O'Donnell <bodonnel@redhat.com>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
>
> diff --git a/man/man8/mkfs.xfs.8 b/man/man8/mkfs.xfs.8
> index a7f70285..84ac50e8 100644
> --- a/man/man8/mkfs.xfs.8
> +++ b/man/man8/mkfs.xfs.8
> @@ -316,12 +316,20 @@ option set. When the option
> is used, the reference count btree feature is not supported and reflink is
> disabled.
> .IP
> -Note: the filesystem DAX mount option (
> +Note: the filesystem-wide DAX mount options (
> .B \-o dax
> -) is incompatible with
> -reflink-enabled XFS filesystems. To use filesystem DAX with XFS, specify the
> +and
> +.B \-o dax=always
> +) are incompatible with
> +reflink-enabled XFS filesystems. To use filesystem-wide DAX with XFS, specify the
> .B \-m reflink=0
> option to mkfs.xfs to disable the reflink feature.
> +Alternatey, use the
s /Alternatey/Alternately
> +.B \-o dax=inode
> +mount option to selectively enable DAX mode on non-reflinked files.
> +See
> +.BR xfs (5)
> +for more information.
> .RE
> .PP
> .PD 0
>
Reviewed-by: Bill O'Donnell <bodonnel@redhat.com>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mkfs.xfs.8: clarify DAX-vs-reflink restrictions in the mkfs.xfs man page
2021-08-27 15:46 ` Bill O'Donnell
@ 2021-08-27 15:47 ` Eric Sandeen
0 siblings, 0 replies; 5+ messages in thread
From: Eric Sandeen @ 2021-08-27 15:47 UTC (permalink / raw)
To: Bill O'Donnell, Eric Sandeen; +Cc: xfs, Bill O'Donnell
On 8/27/21 10:46 AM, Bill O'Donnell wrote:
> On Fri, Aug 27, 2021 at 10:39:18AM -0500, Eric Sandeen wrote:
>> +and
>> +.B \-o dax=always
>> +) are incompatible with
>> +reflink-enabled XFS filesystems. To use filesystem-wide DAX with XFS, specify the
>> .B \-m reflink=0
>> option to mkfs.xfs to disable the reflink feature.
>> +Alternatey, use the
> s /Alternatey/Alternately
Doh! Thanks.
-Eric
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mkfs.xfs.8: clarify DAX-vs-reflink restrictions in the mkfs.xfs man page
2021-08-27 15:39 [PATCH] mkfs.xfs.8: clarify DAX-vs-reflink restrictions in the mkfs.xfs man page Eric Sandeen
2021-08-27 15:46 ` Bill O'Donnell
@ 2021-08-27 15:49 ` Darrick J. Wong
2021-08-27 16:23 ` Eric Sandeen
1 sibling, 1 reply; 5+ messages in thread
From: Darrick J. Wong @ 2021-08-27 15:49 UTC (permalink / raw)
To: Eric Sandeen; +Cc: xfs, Bill O'Donnell
On Fri, Aug 27, 2021 at 10:39:18AM -0500, Eric Sandeen wrote:
> Now that we have the tristate dax mount options, it is possible
> to enable DAX mode for non-reflinked files on a reflink-capable
> filesystem. Clarify this in the mkfs.xfs manpage.
>
> Reported-by: Bill O'Donnell <bodonnel@redhat.com>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> ---
>
> diff --git a/man/man8/mkfs.xfs.8 b/man/man8/mkfs.xfs.8
> index a7f70285..84ac50e8 100644
> --- a/man/man8/mkfs.xfs.8
> +++ b/man/man8/mkfs.xfs.8
> @@ -316,12 +316,20 @@ option set. When the option
> is used, the reference count btree feature is not supported and reflink is
> disabled.
> .IP
> -Note: the filesystem DAX mount option (
> +Note: the filesystem-wide DAX mount options (
> .B \-o dax
> -) is incompatible with
> -reflink-enabled XFS filesystems. To use filesystem DAX with XFS, specify the
> +and
> +.B \-o dax=always
> +) are incompatible with
> +reflink-enabled XFS filesystems. To use filesystem-wide DAX with XFS, specify the
> .B \-m reflink=0
> option to mkfs.xfs to disable the reflink feature.
> +Alternatey, use the
"Alternately..."
> +.B \-o dax=inode
> +mount option to selectively enable DAX mode on non-reflinked files.
/me wonders if this is dangerously close to wading into the muck that is
"Use dax=inode or even no dax option at all, then make sure nobody
shares your file's data blocks to set the DAX fsxattr flag on the file,
and /then/ you can have DAX."
<shrug> But the only blocker I can see is the misspelling above.
--D
> +See
> +.BR xfs (5)
> +for more information.
> .RE
> .PP
> .PD 0
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mkfs.xfs.8: clarify DAX-vs-reflink restrictions in the mkfs.xfs man page
2021-08-27 15:49 ` Darrick J. Wong
@ 2021-08-27 16:23 ` Eric Sandeen
0 siblings, 0 replies; 5+ messages in thread
From: Eric Sandeen @ 2021-08-27 16:23 UTC (permalink / raw)
To: Darrick J. Wong, Eric Sandeen; +Cc: xfs, Bill O'Donnell
On 8/27/21 10:49 AM, Darrick J. Wong wrote:
> On Fri, Aug 27, 2021 at 10:39:18AM -0500, Eric Sandeen wrote:
>> Now that we have the tristate dax mount options, it is possible
>> to enable DAX mode for non-reflinked files on a reflink-capable
>> filesystem. Clarify this in the mkfs.xfs manpage.
>>
>> Reported-by: Bill O'Donnell <bodonnel@redhat.com>
>> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
>> ---
>>
>> diff --git a/man/man8/mkfs.xfs.8 b/man/man8/mkfs.xfs.8
>> index a7f70285..84ac50e8 100644
>> --- a/man/man8/mkfs.xfs.8
>> +++ b/man/man8/mkfs.xfs.8
>> @@ -316,12 +316,20 @@ option set. When the option
>> is used, the reference count btree feature is not supported and reflink is
>> disabled.
>> .IP
>> -Note: the filesystem DAX mount option (
>> +Note: the filesystem-wide DAX mount options (
>> .B \-o dax
>> -) is incompatible with
>> -reflink-enabled XFS filesystems. To use filesystem DAX with XFS, specify the
>> +and
>> +.B \-o dax=always
>> +) are incompatible with
>> +reflink-enabled XFS filesystems. To use filesystem-wide DAX with XFS, specify the
>> .B \-m reflink=0
>> option to mkfs.xfs to disable the reflink feature.
>> +Alternatey, use the
>
> "Alternately..."
"Alternatively,"
>
>> +.B \-o dax=inode
>> +mount option to selectively enable DAX mode on non-reflinked files.
>
> /me wonders if this is dangerously close to wading into the muck that is
> "Use dax=inode or even no dax option at all, then make sure nobody
> shares your file's data blocks to set the DAX fsxattr flag on the file,
> and /then/ you can have DAX."
Perhaps I should drop most of it, and just wave hands vaguely at xfs.5?
-Eric
^ permalink raw reply [flat|nested] 5+ messages in thread
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2021-08-27 15:39 [PATCH] mkfs.xfs.8: clarify DAX-vs-reflink restrictions in the mkfs.xfs man page Eric Sandeen
2021-08-27 15:46 ` Bill O'Donnell
2021-08-27 15:47 ` Eric Sandeen
2021-08-27 15:49 ` Darrick J. Wong
2021-08-27 16:23 ` Eric Sandeen
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