linux-kernel - Re: Power plug off / on - EXT4-fs (sda1): re-mounted. Opts: errors=remount-ro,commit=600

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Date:	Thu, 13 Jan 2011 15:38:09 -0500
From:	Ted Ts'o <tytso@....edu>
To:	Jason Wessel <jason.wessel@...driver.com>
Cc:	"Luis R. Rodriguez" <mcgrof@...il.com>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: Power plug off / on - EXT4-fs (sda1): re-mounted. Opts:
 errors=remount-ro,commit=600

On Thu, Jan 13, 2011 at 02:22:22PM -0600, Jason Wessel wrote:
> 
> That is interesting indeed.  While I am running a substantially
> older kernel ( 2.6.35-24-generic #42-Ubuntu 10.10 ).  I was seeing a
> consistent problem where if you pulled the power cord while the
> system was under heavy I/O load, you could no longer run sync.  The
> jbd2 process just kept on running forever continuously.  Shutdown
> was impossible to because vfs unmount blocked (hold power key for 4+
> seconds...).

Yeah, there were two separate bugs that have been addressed recently;
both were in the generic VFS and writeback code.  One was a fix to do
more efficient forced writeouts at umount time.

The other was a fix so that if new dirty pages are continuously being
created (by having processes always writing more pages, those dastards :-),
to make sync stop by only having it write the pages that were dirty
at the time when the sync was initiated.

					- Ted
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