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Subject2.6.24-rc4-mm1: hostbyte=0x01 driverbyte=0x00 (now bisected)
From
>  git-scsi-misc.patch

Apologies for not looking into the problem earlier. See
http://marc.info/?t=119628022300005&r=1&w=2
"2.6.24-rc3-mm2: Result: hostbyte=0x01 driverbyte=0x00\nend_request: I/O error"
for previous installment.
I've bisected it to the following patch in git-scsi-misc branch.
Revert on top of 2.6.24-rc4-mm1 also helps.

commit 8655a546c83fc43f0a73416bbd126d02de7ad6c0
Author: Hannes Reinecke <hare@suse.de>
Date: Tue Nov 6 09:23:40 2007 +0100

[SCSI] Do not requeue requests if REQ_FAILFAST is set

Any requests with the REQ_FAILFAST flag set should not be requeued
to the requeust queue, but rather terminated directly.
Otherwise the multipath failover will stall until the command
timeout triggers.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 0f44bdb..0da0dd0 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1286,6 +1286,11 @@ int scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
*/
if (!(req->cmd_flags & REQ_PREEMPT))
ret = BLKPREP_DEFER;
+ /*
+ * Return failfast requests immediately
+ */
+ if (req->cmd_flags & REQ_FAILFAST)
+ ret = BLKPREP_KILL;
break;
default:
/*
@@ -1414,6 +1419,17 @@ static inline int scsi_host_queue_ready(struct request_queue *q,
return 1;
}

+static void __scsi_kill_request(struct request *req)
+{
+ struct scsi_cmnd *cmd = req->special;
+ struct scsi_device *sdev = cmd->device;
+
+ cmd->result = DID_NO_CONNECT << 16;
+ atomic_inc(&cmd->device->iorequest_cnt);
+ sdev->device_busy--;
+ __scsi_done(cmd);
+}
+
/*
* Kill a request for a dead device
*/
@@ -1527,8 +1543,16 @@ static void scsi_request_fn(struct request_queue *q)
* accept it.
*/
req = elv_next_request(q);
- if (!req || !scsi_dev_queue_ready(q, sdev))
+ if (!req)
+ break;
+
+ if (!scsi_dev_queue_ready(q, sdev)) {
+ if (req->cmd_flags & REQ_FAILFAST) {
+ scsi_kill_request(req, q);
+ continue;
+ }
break;
+ }

if (unlikely(!scsi_device_online(sdev))) {
sdev_printk(KERN_ERR, sdev,
@@ -1609,8 +1633,12 @@ static void scsi_request_fn(struct request_queue *q)
* later time.
*/
spin_lock_irq(q->queue_lock);
- blk_requeue_request(q, req);
- sdev->device_busy--;
+ if (unlikely(req->cmd_flags & REQ_FAILFAST))
+ __scsi_kill_request(req);
+ else {
+ blk_requeue_request(q, req);
+ sdev->device_busy--;
+ }
if(sdev->device_busy == 0)
blk_plug_device(q);
out:

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