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Subject: Re: [patch] fix the ext3 data=journal unmount bug
From: "Stephen C. Tweedie" <sct@redhat.com>
To: Andrew Morton <akpm@digeo.com>
Cc: Chris Mason <mason@suse.com>, lkml <linux-kernel@vger.kernel.org>,
       ext3 users list <ext3-users@redhat.com>
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Date: 06 Dec 2002 19:57:55 +0000
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Hi,

On Fri, 2002-12-06 at 19:45, Andrew Morton wrote:

> > I see what ext3 gains from your current patch in the unmount case, but
> > the sync case is really unchanged because of interaction with kupdate.
> 
> True.  And I'd like /bin/sync to _really_ be synchronous because
> I use `reboot -f' all the time.  Even though SuS-or-POSIX say that
> sync() only needs to _start_ the IO.  That's rather silly.

But at the same time I'd like to avoid sync becoming serialised on its
writes.  If you've got a lot of filesystems mounted, doing each
filesystem's sync sequentially and synchronously is going to be a lot
slower than allowing async syncs.  In other words, for sync(2) we really
want async commit submission followed by a synchronous wait for
completion.  And that's probably more churn than I'd like to see at this
stage for 2.4.

Cheers, 
 Stephen

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