xfs
[Top] [All Lists]

Re: synchronization of XFS

To: Chris Wedgwood <cw@xxxxxxxx>
Subject: Re: synchronization of XFS
From: Stefan Smietanowski <stesmi@xxxxxxxxxx>
Date: Fri, 09 Apr 2004 00:29:24 +0200
Cc: "IKARASHI, Seiichi" <ikarashi@xxxxxxxxxxxxxxxx>, Steve Lord <lord@xxxxxxx>, Christoph Hellwig <hch@xxxxxxxxxxxxx>, linux-xfs@xxxxxxxxxxx
In-reply-to: <20040408202535.GA31618@dingdong.cryptoapps.com>
References: <406365DE.2050006@stesmi.com> <4067B496.8060501@miraclelinux.com> <40682301.50508@xfs.org> <4074ABB3.500@stesmi.com> <20040408074826.GA25688@dingdong.cryptoapps.com> <40752DF3.2070109@stesmi.com> <407543A1.7090306@miraclelinux.com> <4075473E.40702@stesmi.com> <20040408182419.GA30488@dingdong.cryptoapps.com> <4075B371.8050705@stesmi.com> <20040408202535.GA31618@dingdong.cryptoapps.com>
Sender: linux-xfs-bounce@xxxxxxxxxxx
User-agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7b) Gecko/20040316
>>I noticed as much. And guess what - it worked!
> 
> ok cool, that also confirms what people suspected isgoing on really is
> 
> i still wonder about grub using O_DIRECT though for another reason,
> that is corruption/nasties when doing block access on a mounted fs

Yeah, but it's only reading it, not writing it.

Nasties - could happen I guess. Corruption - don't see exactly
how that could happen.

> hch --- can you comment here perhaps?  would that be a dafer way to
> go?
> 
>>That's nice. Oh well, nothing to worry about, it just means
>>that if you don't have a seperate /boot your root partition
>>will be frozen and unfrozen twice.
> 
> freezing a second time w/o much dirty data will be pretty quick and
> painless

Yeah, I can't clock any difference here at all.

>>Right. Well, what I have left to test is what happens if the root
>>and/or /boot partition isn't xfs. I'll only try using ext3 though.
> 
> maybe hack the installer to check the fs-type then perhaps and do thr
> freeze only if it's xfs using the ioctl's rather than calling out to
> an external program

Checking the FS type - yes, it involves some hackery pokery but it is
doable. Right now all it does is check if xfs_freeze is installed and
calls it twice each for both / and /boot (one freeze and one unfreeze).

> let me know if you want example code for that

Well, the installer's written in python so I need to call out to an
external program anyway (don't I?) to do the ioctl so I don't see
the win there - it's either calling some_program or xfs_freeze.

To be strict - it's actually not the installer itself I'm hacking on
right now - it's booty, but it's also written in python so the same
applies.

Latest status is that I have tested the following combinations:

/ xfs => works
/ ext3 => works
/, /boot xfs => works
/, /boot ext3 => works
/ xfs, /boot ext3 => works
/ ext3, /boot xfs => works

That's basically all combinations possible using ext3 and/or xfs.

xfs_freeze simply tells us that it only works on xfs if I call it
on an ext3 part and if we don't have any xfs at all then the program
xfs_freeze isn't installed and then it's not called at all.

As soon as I resurrect the x86 distro building machine I'll incoroprate
these changes into the installer there and then there'll be a new DVD
out that works even better now :)

// Stefan


<Prev in Thread] Current Thread [Next in Thread>