State of ext4 auto_da_alloc-like workarounds in XFS

State of ext4 auto_da_alloc-like workarounds in XFS

[Vallo Kallaste]

Hi

The ext4 workaround for wrong-but-common truncate/rename cases can be found at
https://en.wikipedia.org/wiki/Ext4#Delayed_allocation_and_potential_data_loss
This is the default "auto_da_alloc" mount option.

There is no mention of similar workaround in XFS FAQ at
http://xfs.org/index.php/XFS_FAQ nor
Wiki article at http://en.wikipedia.org/wiki/XFS
I suggest adding such a section.

I have read the thread at
http://article.gmane.org/gmane.comp.file-systems.xfs.general/53366
There seems to be definite answer at the top of
http://article.gmane.org/gmane.comp.file-systems.xfs.general/53376

But besides that I found
http://article.gmane.org/gmane.linux.kernel/812588 where it's mentioned that
/--/
The bigger problem from my perspective is that XFS is only doing this for the
truncate case, and (from what I've been told) not for the rename case.
/--/

I'd like to know the current state of ext4 auto_da_alloc-like workarounds in XFS,
particularly for RHEL7. Considering the two cases in
https://en.wikipedia.org/wiki/Ext4#Delayed_allocation_and_potential_data_loss
is XFS behaving the same as ext4, both mounted with default options?

thanks,
-- 
Vallo

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Re: State of ext4 auto_da_alloc-like workarounds in XFS

[Eric Sandeen]

On 12/21/15 12:37 PM, Vallo Kallaste wrote:
> Hi
> 
> The ext4 workaround for wrong-but-common truncate/rename cases can be found at
> https://en.wikipedia.org/wiki/Ext4#Delayed_allocation_and_potential_data_loss
> This is the default "auto_da_alloc" mount option.
> 
> There is no mention of similar workaround in XFS FAQ at
> http://xfs.org/index.php/XFS_FAQ nor
> Wiki article at http://en.wikipedia.org/wiki/XFS
> I suggest adding such a section.
> 
> I have read the thread at
> http://article.gmane.org/gmane.comp.file-systems.xfs.general/53366
> There seems to be definite answer at the top of
> http://article.gmane.org/gmane.comp.file-systems.xfs.general/53376
> 
> But besides that I found
> http://article.gmane.org/gmane.linux.kernel/812588 where it's mentioned that
> /--/
> The bigger problem from my perspective is that XFS is only doing this for the
> truncate case, and (from what I've been told) not for the rename case.
> /--/
> 
> I'd like to know the current state of ext4 auto_da_alloc-like workarounds in XFS,
> particularly for RHEL7. Considering the two cases in
> https://en.wikipedia.org/wiki/Ext4#Delayed_allocation_and_potential_data_loss
> is XFS behaving the same as ext4, both mounted with default options?

The sync-on-close-after-file-got-truncated case has been handled since 2007; see

https://git.kernel.org/cgit/linux/kernel/git/dgc/linux-xfs.git/commit/?id=ba87ea699ebd9dd577bf055ebc4a98200e337542

The sync-after-rename behavior was suggested and rejected for xfs, see

http://marc.info/?t=139845506300002&r=1&w=2

If you'd like to add this information to the XFS wiki, please do so!

Thanks,
-Eric

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Re: State of ext4 auto_da_alloc-like workarounds in XFS

[Vallo Kallaste]

On Mon, Dec 21, 2015 at 12:48:31PM -0600, Eric Sandeen <sandeen@sandeen.net> wrote:

[...]
> > I'd like to know the current state of ext4 auto_da_alloc-like workarounds in XFS,
> > particularly for RHEL7. Considering the two cases in
> > https://en.wikipedia.org/wiki/Ext4#Delayed_allocation_and_potential_data_loss
> > is XFS behaving the same as ext4, both mounted with default options?
> 
> The sync-on-close-after-file-got-truncated case has been handled since 2007; see
> 
> https://git.kernel.org/cgit/linux/kernel/git/dgc/linux-xfs.git/commit/?id=ba87ea699ebd9dd577bf055ebc4a98200e337542
> 
> The sync-after-rename behavior was suggested and rejected for xfs, see
> 
> http://marc.info/?t=139845506300002&r=1&w=2
> 
> If you'd like to add this information to the XFS wiki, please do so!

Thanks, this is an exemplary answer, not to mention lightning fast as well!

I would consider if Wiki had at http://xfs.org/index.php/Special:RequestAccount page:
* Privacy policy http://xfs.org/index.php/XFS.org:Privacy_policy
* Terms of Service http://xfs.org/index.php?title=XFS.org:Terms_of_Service&action=edit&redlink=1

The latter being something I must read and agree on before I can request a user
account.

BR,
-- 
Vallo

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Re: State of ext4 auto_da_alloc-like workarounds in XFS

[Eric Sandeen]

On 12/21/15 1:37 PM, Vallo Kallaste wrote:
> On Mon, Dec 21, 2015 at 12:48:31PM -0600, Eric Sandeen <sandeen@sandeen.net> wrote:
> 
> [...]
>>> I'd like to know the current state of ext4 auto_da_alloc-like workarounds in XFS,
>>> particularly for RHEL7. Considering the two cases in
>>> https://en.wikipedia.org/wiki/Ext4#Delayed_allocation_and_potential_data_loss
>>> is XFS behaving the same as ext4, both mounted with default options?
>>
>> The sync-on-close-after-file-got-truncated case has been handled since 2007; see
>>
>> https://git.kernel.org/cgit/linux/kernel/git/dgc/linux-xfs.git/commit/?id=ba87ea699ebd9dd577bf055ebc4a98200e337542
>>
>> The sync-after-rename behavior was suggested and rejected for xfs, see
>>
>> http://marc.info/?t=139845506300002&r=1&w=2
>>
>> If you'd like to add this information to the XFS wiki, please do so!
> 
> Thanks, this is an exemplary answer, not to mention lightning fast as well!
> 
> I would consider if Wiki had at http://xfs.org/index.php/Special:RequestAccount page:
> * Privacy policy http://xfs.org/index.php/XFS.org:Privacy_policy
> * Terms of Service http://xfs.org/index.php?title=XFS.org:Terms_of_Service&action=edit&redlink=1
> 
> The latter being something I must read and agree on before I can request a user
> account.

Hohum...

Russell, can you either remove the requirement for reading a nonexistent page, or
add that page?

Thanks,
-Eric

> BR,
> 

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