From: Eric Sandeen <sandeen@redhat.com>
Subject: Re: Apparent serious progressive ext4 data corruption bug in 3.6.3
 (and other stable branches?)
Date: Sun, 28 Oct 2012 21:35:58 -0500
Message-ID: <508DEB8E.10101@redhat.com>
References: <20121026211542.GE8614@thunk.org> <87haphx76u.fsf@spindle.srvr.nix> <20121027002258.GB31030@thunk.org> <873910xevu.fsf@spindle.srvr.nix> <20121027175534.GA7783@thunk.org> <87fw4zzra3.fsf@spindle.srvr.nix> <508C4FE5.1030102@redhat.com> <508C633F.4070100@redhat.com> <20121029010012.GE9161@thunk.org> <508DE8D3.1050101@redhat.com> <20121029023430.GB9365@thunk.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
To: "Theodore Ts'o" <tytso@mit.edu>, Nix <nix@esperi.org.uk>,
	linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org,
	gregkh@linuxfoundation.org
In-Reply-To: <20121029023430.GB9365@thunk.org>
Sender: linux-ext4-owner@vger.kernel.org

On 10/28/12 9:34 PM, Theodore Ts'o wrote:
> On Sun, Oct 28, 2012 at 09:24:19PM -0500, Eric Sandeen wrote:
>> Yeah, I knew it wasn't ;)  I did resend 
>> [PATCH] ext4: fix unjournaled inode bitmap modification
>> which is a bit more involved.
> 
> Yeah, sorry, I didn't see your updated patch at first, since this mail
> thread is one complicated tangle.  :-(
> 
>> That'll get_write_access on the same buffer over and over, I suppose
>> it's ok, but the patch I sent tries to minimize that, and call
>> ext4_handle_release_buffer if we're not going to use it (which is
>> a no-op today anyway and not normally used I guess...)
> 
> Well, it's really rare that we will go through that loop more than
> once; it only happens if we have multiple processes race against each
> other trying to grab the same inode.
> 
>> If ext4_handle_release_buffer() is dead code now, and repeated calls
>> via repeat_in_this_group: are no big deal, then your version looks fine.
> 
> Yeah, I think it's pretty much dead code.  At least, I can't think of
> a good reason why we would want to actually try to handle
> ext4_handle_release_buffer() to claw back the transaciton credit.  And
> if we do, we'll have to do a sweep through the entire ext4 codebase
> anyway.

Yeah, seems that way.

Then your simpler version is probably the way to go.

Thanks,
-Eric

> 						- Ted
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>