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Message-ID: <87zl5hsal8.fsf@basil.nowhere.org>
Date: Thu, 17 Dec 2009 19:45:55 +0100
From: Andi Kleen <andi@...stfloor.org>
To: Christoph Hellwig <hch@...radead.org>
Cc: tytso@....edu, Linus Torvalds <torvalds@...ux-foundation.org>,
Kyle McMartin <kyle@...artin.ca>, linux-parisc@...r.kernel.org,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [git patches] xfs and block fixes for virtually indexed arches
Christoph Hellwig <hch@...radead.org> writes:
> On Thu, Dec 17, 2009 at 11:30:36AM -0500, tytso@....edu wrote:
>> That's because apparently the iSCSI and DMA blocks assume that they
>> have Real Pages (tm) passed to block I/O requests, and apparently XFS
>> ran into problems when sending vmalloc'ed pages. I don't know if this
>> is a problem if we pass the bio layer addresses coming from the SLAB
>> allocator, but oral tradition seems to indicate this is problematic,
>> although no one has given me the full chapter and verse explanation
>> about why this is so.
>
> Actually at least iscsi now has a workaround for that by checking for
> PageSlab. Back when we deal with the XFS issue that check was only
> available with debug options enabled. I tried to sort it out by
> agreeing with the block and iscsi folks that either
DRBD has the same workaround as well:
if (disable_sendpage || (page_count(page) < 1) || PageSlab(page))
But it seems like a gross hack to me. Perhaps this should be
passed as some sort of BIO attribute?
-Andi
--
ak@...ux.intel.com -- Speaking for myself only.
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