From: Mike Christie <michaelc@cs.wisc.edu>
To: torn5 <torn5@shiftmail.org>
Cc: linux-ext4@vger.kernel.org,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>
Subject: Re: Ext4 and scsi commands resubmission
Date: Tue, 28 Dec 2010 22:43:46 -0600 [thread overview]
Message-ID: <4D1ABC82.5050909@cs.wisc.edu> (raw)
In-Reply-To: <4D19BEF6.5010007@shiftmail.org>
On 12/28/2010 04:41 AM, torn5 wrote:
> Hello all,
>
> in open-iscsi, when network connectivity is lost, scsi commands that
> were in-flight at the moment of disconnection are failed to the SCSI layer.
> These get resubmitted up to 5 times by the SCSI layer (or so is written
> in the open-iscsi docs) and after that they are held in the queue
> (device "blocked") until the network connection is restored.
>
> Now the question is: when SCSI resubmits commands to a device, I suppose
> they go to the end of the queue for the device, and not at the head like
> they were. Am I right?
The request goes to eh head. scsi layer calls
blk_requeue_request->elv_requeue_request->
elv_insert(ELEVATOR_INSERT_REQUEUE) and ELEVATOR_INSERT_REQUEUE's case
falls through to the ELEVATOR_INSERT_FRONT case.
prev parent reply other threads:[~2010-12-29 4:43 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-28 10:41 Ext4 and scsi commands resubmission torn5
2010-12-29 4:43 ` Mike Christie [this message]
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