From: Jeff Garzik <jeff@garzik.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>,
Jens Axboe <jens.axboe@oracle.com>,
LKML <linux-kernel@vger.kernel.org>, Tejun Heo <htejun@gmail.com>,
linux-ide@vger.kernel.org, linux-scsi@vger.kernel.org
Subject: Re: regression: CD burning (k3b) went broke
Date: Tue, 26 Feb 2008 19:46:12 -0500 [thread overview]
Message-ID: <47C4B2D4.109@garzik.org> (raw)
In-Reply-To: <20080226150845.2196bc1a.akpm@linux-foundation.org>
Andrew Morton wrote:
> On Tue, 26 Feb 2008 14:36:43 +0100 Mike Galbraith <efault@gmx.de> wrote:
>
>> On Tue, 2008-02-26 at 10:48 +0100, Mike Galbraith wrote:
>>> Greetings,
>>>
>>> I straced both a good and a bad kernel (good being .git with attached
>>> revert patch applied) and filtered/diffed/merged the output. Scroll
>>> down to "HERE" to see the problem (resid).
>>>
>>> I'm poking around, but not having much luck.
>
> cc's added.
>
> I'm told this is part of "Tejun's DMA drain handling".
Correct.
>> Seems the problem is data_len changes, but raw_data_len doesn't. I've
>> not the foggiest IO-land clue, but k3b works again, so the below may
>> have some diagnostic value.
>
> So this change fixes a bug? Can we have a recap of how it does this?
>
>> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
>> index ba21d97..7a6f784 100644
>> --- a/drivers/scsi/scsi_lib.c
>> +++ b/drivers/scsi/scsi_lib.c
>> @@ -871,7 +871,7 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
>> scsi_end_bidi_request(cmd);
>> return;
>> }
>> - req->data_len = scsi_get_resid(cmd);
>> + req->data_len = req->raw_data_len = scsi_get_resid(cmd);
>> }
I would love to get an answer as to what data_len (and of course
raw_data_len) should be set to AFTER the command completes, which is
what is going on here.
I can see the above being correct -- scsi_get_resid() returns the length
of the left-over data after the command is processed -- but I am mainly
curious why setting [raw_]data_len matters after I/O completion.
Jeff
next prev parent reply other threads:[~2008-02-27 0:46 UTC|newest]
Thread overview: 109+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-02-21 8:42 regression: CD burning (k3b) went broke Mike Galbraith
2008-02-22 7:32 ` Jens Axboe
2008-02-23 7:42 ` Mike Galbraith
2008-02-24 7:54 ` Mike Galbraith
2008-02-26 9:48 ` Mike Galbraith
2008-02-26 13:36 ` Mike Galbraith
2008-02-26 23:08 ` Andrew Morton
2008-02-27 0:46 ` Jeff Garzik [this message]
2008-02-27 2:58 ` Mike Galbraith
2008-02-27 2:24 ` Mike Galbraith
2008-02-27 6:00 ` Mike Galbraith
2008-02-27 7:07 ` Mike Galbraith
2008-02-28 7:43 ` Tejun Heo
2008-02-28 8:20 ` Mike Galbraith
2008-02-28 8:50 ` [PATCH] block: fix residual byte count handling Tejun Heo
2008-02-28 15:35 ` Jens Axboe
2008-02-28 15:46 ` Tejun Heo
2008-02-29 16:47 ` James Bottomley
2008-02-29 20:11 ` Jens Axboe
2008-03-01 6:17 ` Tejun Heo
2008-03-01 15:19 ` James Bottomley
2008-03-02 14:52 ` FUJITA Tomonori
2008-03-02 18:46 ` Mike Christie
2008-03-03 3:27 ` Mike Galbraith
2008-03-03 2:40 ` Tejun Heo
2008-03-03 3:59 ` FUJITA Tomonori
2008-03-03 4:09 ` Tejun Heo
2008-03-03 6:08 ` [PATCH 1/2] " Tejun Heo
2008-03-03 6:10 ` [PATCH] block: separate out padding from alignment Tejun Heo
2008-03-03 18:27 ` James Bottomley
2008-03-03 8:26 ` [PATCH] block: fix residual byte count handling FUJITA Tomonori
2008-03-03 9:21 ` Tejun Heo
2008-03-03 12:17 ` FUJITA Tomonori
2008-03-03 13:38 ` Tejun Heo
2008-03-03 13:50 ` FUJITA Tomonori
2008-03-03 13:55 ` Tejun Heo
2008-03-03 14:01 ` FUJITA Tomonori
2008-03-03 14:22 ` Tejun Heo
2008-03-03 14:52 ` FUJITA Tomonori
2008-03-03 22:44 ` Tejun Heo
2008-03-04 2:11 ` FUJITA Tomonori
2008-03-04 2:32 ` Tejun Heo
2008-03-04 8:53 ` FUJITA Tomonori
2008-03-04 8:59 ` Jens Axboe
2008-03-04 9:06 ` FUJITA Tomonori
2008-03-04 9:22 ` FUJITA Tomonori
2008-03-04 9:30 ` Tejun Heo
2008-03-04 9:35 ` Jens Axboe
2008-03-04 9:40 ` Tejun Heo
2008-03-04 9:46 ` Jens Axboe
2008-03-04 12:37 ` Mike Galbraith
2008-03-04 12:39 ` Jens Axboe
2008-03-04 12:43 ` Mike Galbraith
2008-03-04 12:58 ` Mike Galbraith
2008-03-04 13:03 ` Jens Axboe
2008-03-04 14:25 ` Mike Galbraith
2008-03-04 18:17 ` Jens Axboe
2008-03-04 18:29 ` Jens Axboe
2008-03-04 18:35 ` Mike Galbraith
2008-03-04 18:45 ` Jens Axboe
2008-03-04 18:49 ` Mike Galbraith
2008-03-04 18:54 ` Jens Axboe
2008-03-04 19:26 ` Mike Galbraith
2008-03-04 19:28 ` Jens Axboe
2008-03-04 16:04 ` James Bottomley
2008-03-04 18:46 ` Jens Axboe
2008-03-04 17:34 ` walt
2008-03-04 17:59 ` Tejun Heo
2008-03-04 19:42 ` Kiyoshi Ueda
2008-03-04 12:40 ` Tejun Heo
2008-03-04 12:45 ` Mike Galbraith
2008-03-04 13:30 ` FUJITA Tomonori
2008-03-04 13:50 ` Tejun Heo
2008-03-04 16:17 ` Tejun Heo
2008-03-04 16:42 ` Tejun Heo
2008-03-04 18:26 ` Boaz Harrosh
2008-03-04 18:35 ` Tejun Heo
2008-03-04 18:27 ` James Bottomley
2008-03-04 18:33 ` Tejun Heo
2008-03-04 18:45 ` Mike Galbraith
2008-03-04 19:25 ` Jens Axboe
2008-03-04 19:33 ` Mike Galbraith
2008-03-04 19:34 ` Jens Axboe
2008-03-04 19:19 ` FUJITA Tomonori
2008-03-04 23:33 ` Tejun Heo
2008-03-04 23:54 ` Tejun Heo
2008-03-05 0:26 ` FUJITA Tomonori
2008-03-05 0:44 ` Tejun Heo
2008-03-06 4:56 ` FUJITA Tomonori
2008-03-06 5:02 ` Tejun Heo
2008-03-05 10:16 ` [PATCH] blk: missing add of padded bytes to io completion byte count Boaz Harrosh
2008-03-05 12:28 ` Mike Galbraith
2008-03-05 12:33 ` Jens Axboe
2008-03-05 12:46 ` Boaz Harrosh
2008-03-05 12:48 ` Jens Axboe
2008-03-05 13:45 ` Tejun Heo
2008-03-05 13:51 ` Jens Axboe
2008-03-05 14:08 ` Tejun Heo
2008-03-05 15:21 ` James Bottomley
2008-03-06 4:41 ` FUJITA Tomonori
2008-03-06 13:41 ` Jens Axboe
2008-03-07 0:07 ` Tejun Heo
2008-03-07 15:07 ` FUJITA Tomonori
2008-03-08 1:06 ` Tejun Heo
2008-03-20 12:54 ` FUJITA Tomonori
2008-03-05 14:46 ` Boaz Harrosh
2008-03-05 15:11 ` Tejun Heo
2008-03-06 5:02 ` FUJITA Tomonori
2008-03-04 9:29 ` [PATCH] block: fix residual byte count handling Tejun Heo
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