From: Jan Kara <jack@suse.cz>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Jan Kara <jack@suse.cz>, Boaz Harrosh <bharrosh@panasas.com>,
tmhikaru@gmail.com,
Kernel development list <linux-kernel@vger.kernel.org>,
USB list <linux-usb@vger.kernel.org>,
Jens Axboe <axboe@kernel.dk>,
SCSI development list <linux-scsi@vger.kernel.org>,
linux-ext4@vger.kernel.org
Subject: Re: Weird I/O errors with USB hard drive not remounting filesystem readonly
Date: Tue, 24 Nov 2009 20:56:08 +0100 [thread overview]
Message-ID: <20091124195607.GC16662@quack.suse.cz> (raw)
In-Reply-To: <Pine.LNX.4.44L0.0911241418440.2881-100000@iolanthe.rowland.org>
On Tue 24-11-09 14:28:35, Alan Stern wrote:
> On Tue, 24 Nov 2009, Jan Kara wrote:
>
> > My naive guess would be that those non-retried reads were actually
> > readahead. That's not retried if I remember correctly. Later, when we
> > really needed the data, we sent another read request...
>
> That would be my guess too. I don't know how to verify it, though.
>
> If you're interested in pursuing this farther, I can show you how to
> generate equivalent errors on demand using an emulated USB drive.
> At this point it's not clear how much more one could learn by doing
> this, however.
After digging in block layer code, it's as we suspected:
In case of host error DID_ERROR (which is our case), scsi request is
retried iff it is not a FAILFAST request which is set if bio is doing
readahead... So this is explained and everything behaves as it should.
Thanks everybody involved :).
Honza
next prev parent reply other threads:[~2009-11-24 19:56 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20091113050907.GA4965@roll>
[not found] ` <20091119160700.GC2943@atrey.karlin.mff.cuni.cz>
[not found] ` <20091120082359.GA29538@roll>
[not found] ` <20091120094641.GB15422@duck.suse.cz>
2009-11-23 8:09 ` tmhikaru
2009-11-23 10:54 ` Jan Kara
2009-11-23 15:06 ` Alan Stern
2009-11-23 16:09 ` Jan Kara
2009-11-23 18:20 ` Alan Stern
2009-11-23 18:54 ` Jan Kara
2009-11-23 19:50 ` tmhikaru
2009-11-23 20:06 ` tmhikaru
2009-11-23 20:33 ` Alan Stern
2009-11-23 23:42 ` tmhikaru
2009-11-24 17:16 ` Alan Stern
2009-11-24 17:47 ` Boaz Harrosh
2009-11-24 19:28 ` Alan Stern
2009-11-24 19:56 ` Jan Kara [this message]
2009-11-24 20:13 ` Alan Stern
2009-11-24 20:39 ` Jan Kara
2009-11-24 21:50 ` tmhikaru
2009-11-24 22:23 ` tmhikaru
2009-11-25 8:42 ` Jan Kara
2009-11-25 9:37 ` tmhikaru
2009-11-25 16:10 ` Alan Stern
2009-11-27 9:43 ` tmhikaru
2009-11-27 13:13 ` Jan Kara
2009-11-27 17:58 ` Alan Stern
2009-11-29 4:30 ` tmhikaru
2009-11-24 18:00 ` Jan Kara
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