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

To: Mark Goodwin <markgw@xxxxxxx>, Bill Kendall <wkendall@xxxxxxx>, xfs-dev <xfs-dev@xxxxxxx>, xfs@xxxxxxxxxxx
Subject: Re: [PATCH] xfsdump support for 64K page size
From: Bill Kendall <wkendall@xxxxxxx>
Date: Fri, 09 Jan 2009 13:36:30 -0600
In-reply-to: <20090108222800.GG9448@disturbed>
References: <4964C5EF.3060308@xxxxxxx> <4965629C.2000703@xxxxxxx> <20090108222800.GG9448@disturbed>
User-agent: Thunderbird 1.5.0.14ubu (X11/20080502)
Dave Chinner wrote:
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.:

Right, only difference is that I removed the asserts rather than
just having them commented out. In my determination the asserts
are totally bogus -- there isn't a dependency on the system's
page size in the inomap code.


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

Sorry, didn't recall that you posted the patch to this list.
I got your patch off of the internal bug db.


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....

The inomap code uses xfsdump's PGSZ variable, which is fixed at 4K.
There's no dependency here on the system's actual page size. I was
able to dump and then restore on a system with a different page size.


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

NACK. Lets do a proper review cycle first.

Once that is done, I suggest we put Dave's original patches in the
-dev trees. That way it'll have proper attribution as well as commit
messages with some detail.

Bill

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