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Re: [PATCH] xfsdump support for 64K page size

To: Mark Goodwin <markgw@xxxxxxx>
Subject: Re: [PATCH] xfsdump support for 64K page size
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Fri, 9 Jan 2009 09:28:00 +1100
Cc: Bill Kendall <wkendall@xxxxxxx>, xfs-dev <xfs-dev@xxxxxxx>, xfs@xxxxxxxxxxx
In-reply-to: <4965629C.2000703@xxxxxxx>
Mail-followup-to: Mark Goodwin <markgw@xxxxxxx>, Bill Kendall <wkendall@xxxxxxx>, xfs-dev <xfs-dev@xxxxxxx>, xfs@xxxxxxxxxxx
References: <4964C5EF.3060308@xxxxxxx> <4965629C.2000703@xxxxxxx>
User-agent: Mutt/1.5.18 (2008-05-17)
On Thu, Jan 08, 2009 at 01:19:08PM +1100, Mark Goodwin wrote:
> Bill Kendall wrote:
> > Various fixes to allow xfsdump/xfsrestore to work with 64K
> > page size. This is essentially Chinner's patch from a while
> > back.
> >
> > Signed-off-by: Bill Kendall <wkendall@xxxxxxx>
> 
> Lachlan reviewed and ack'd this on an internal list and I've committed
> it (on Bill's behalf) as follows :
> 
> git://oss.sgi.com/xfs/cmds/xfsdump.git
>       commit 9502587dbbfdd465958889a568dc2842f10b1ff9
>       Author: Mark Goodwin <markgw@xxxxxxx>
>       Date:   Thu Jan 8 12:37:53 2009 +1100
> 
>           Various fixes to allow xfsdump/xfsrestore to work with 64K
>           page size. This is essentially Chinner's patch from a while
>           back.

I guess I don't have a real name ;)

BTW, these changes are the *exact* patches I sent back in March.
I note that the change logs from those patches have been dropped
on the floor. i.e.:

http://oss.sgi.com/archives/xfs/2008-05/msg00339.html

The extended attr buffer size used by xfsdump is based on page size.
The maximum buffer size the kernel will accept is 64k. On a 64k page
machine, the default buffer size will be rejected by the kernel,
thereby breaking dump and restore.

Limit the buffer size to XATTR_LIST_MAX in dump, restore and
libhandle so the kernel won't reject otherwise valid requests.

----

http://oss.sgi.com/archives/xfs/2008-05/msg00340.html

xfsrestore has assumptions about page size built into the inode hunk
size in the dump format. Seems to be a stupid thing to do - this
patch simply comments out the asserts to allow it to work on
64k page size machine, but probably subtly breaks the code.
Nasty hack, really, but allows xfsqa tests to pass.

----

I'd also like to know what validation has been done of the second
patch. e.g. is it going to break when dump and restore are done on
machines of different page size? This is why I didn't sign-off on
the second patch....

> In any case, Christoph, please pull these commits into your kernel.org 
> -dev trees.

NACK. Lets do a proper review cycle first.

Cheers,

Dave.
-- 
Dave Chinner
david@xxxxxxxxxxxxx

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