linux-kernel - Re: [SCSI][REGRESSION][BISECTED] Disk errors loop forever in 2.6.29

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Date:	Thu, 19 Feb 2009 21:48:54 +0000
From:	James Bottomley <James.Bottomley@...senPartnership.com>
To:	Sitsofe Wheeler <sitsofe@...oo.com>
Cc:	Alan Stern <stern@...land.harvard.edu>,
	linux-kernel@...r.kernel.org, rjw@...k.pl,
	Ingo Molnar <mingo@...e.hu>, linux-scsi@...r.kernel.org
Subject: Re: [SCSI][REGRESSION][BISECTED] Disk errors loop forever in 2.6.29

On Thu, 2009-02-19 at 13:11 -0800, Sitsofe Wheeler wrote:
> > From: James Bottomley <James.Bottomley@...senPartnership.com>
> >
> > Can you try this patch ... it was something I meant to get into 2.6.29
> > but forgot about.  The key problem that you seem to be hitting is that
> > the requeue evades the timeout check.  Moving the timeout check to block
> > should fix that.
> 
> Even by itself this patch works although the behaviour is now different
> to that of 2.6.28.  Whereas in 2.6.28 it would timeout very quickly
> (after about 1 or 2 seconds) it now times out after 30 seconds
> (initially I hadn't realised that it would be so much longer). The
> other difference is that the failure becomes cached - trying to reread
> the same area using dd instantly fails from now on without any more disk
> IO/kernel error messages until echo 1 > /proc/sys/vm/drop_caches is
> issued. Before it would always go straight to the disk for the unread
> section and the kernel spew would be repeated before the failure.

Well, the block patch is more of a catch all:  without it apparently the
scsi_io_completion() rewrite has several cases where it will apparently
loop forever.

Your specific behaviour change seems to be a bug in the way the rewrite
is handling ABORTED_COMMAND.  Could you try the patch below (with or
without the block patch, it shouldn't matter) and see if it gets you
back to 2.6.28 behaviour?

Thanks,

James

---

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index c034841..4b13e36 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -850,12 +850,11 @@ void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 				action = ACTION_FAIL;
 			break;
 		case ABORTED_COMMAND:
+			action = ACTION_FAIL;
 			if (sshdr.asc == 0x10) { /* DIF */
 				description = "Target Data Integrity Failure";
-				action = ACTION_FAIL;
 				error = -EILSEQ;
-			} else
-				action = ACTION_RETRY;
+			}
 			break;
 		case NOT_READY:
 			/* If the device is in the process of becoming


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