Subject: Re: [PATCH] Allow SysRq emergency sync to thaw frozen filesystems
From: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
To: Eric Sandeen <sandeen@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-fsdevel@vger.kernel.org,
       linux-kernel@vger.kernel.org, t-sato@yk.jp.nec.com
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References: <496EB639.6090800@redhat.com>
	 <20090115162031.a512232b.akpm@linux-foundation.org>
	 <497003CC.8030503@redhat.com>
	 <1232122907.15209.3.camel@norville.austin.ibm.com>
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Date: Fri, 16 Jan 2009 10:42:21 -0600
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On Fri, 2009-01-16 at 10:21 -0600, Dave Kleikamp wrote:
> On Thu, 2009-01-15 at 21:49 -0600, Eric Sandeen wrote:

> > oh, hrm.  Maybe I didn't think enough about how it's handed off to
> > pdflush; I could rearrange if that makes sense?  Or maybe handing to
> > pdflush is wrong, it was just so convenient....
> 
> I don't understand the reason for handing it to pdflush.  I would expect
> thaw to be very fast.  Do we expect it to block anywhere, and if so, for
> very long?  Not that I see any problem with it.

Eric pointed out on irc that this is in interrupt context, so even
taking a mutex is not allowed.  I now agree that handing it to pdflush
is reasonable.

Shaggy
-- 
David Kleikamp
IBM Linux Technology Center

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