From: Rob Evers <revers@redhat.com>
Date: Wed, 15 Sep 2010 21:18:35 -0400
Subject: [scsi] fix disk spinup for shorter path restore times
Message-id: <20100915211321.27913.71062.sendpatchset@localhost.localdomain>
Patchwork-id: 28243
O-Subject: [RHEL5.6 PATCH] scsi: Spinning up disk is observed on standby paths
	until timeout, resulting in longer path restoration.
Bugzilla: 608109
RH-Acked-by: Jarod Wilson <jarod@redhat.com>
RH-Acked-by: Mike Christie <mchristi@redhat.com>
RH-Acked-by: Tomas Henzl <thenzl@redhat.com>

scsi: Spinning up disk is observed on standby paths until timeout, resulting in longer path restoration.

https://bugzilla.redhat.com/show_bug.cgi?id=608109

On Fri, Feb 20, 2009 at 12:03:58PM +0000, Rengarajan, Narayanan (STSD) wrote:
Spinning up disk is observed on standby paths until timeout, resulting in longer
path restoration time in 2.6.27 kernel.
Steps to reproduce:
1. present a standby lun to the host
2. do a discovery from the host (scan the scsi bus)  3. Spinning of disks is
observed in  /var/log/messages
Whenever a device goes offline and comes back, the new sd device takes longer time
to get created. This is because of the spinning up of disk in sd_spinup_disk
fuction as the standby paths would return device not ready with 0x04/0x0b asc/ascq.

Commit id from storage-tree: 3dd6f92a1a7ad85c54d47fd9d73371a32c0bde4

https://brewweb.devel.redhat.com/taskinfo?taskID=2764725

Bug fix tested at HP against -201.el5 where it is reported to have
fixed the problem seen.

Sanity tested by me.

Signed-off-by: Jarod Wilson <jarod@redhat.com>

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index a8ab20a..4c0deab 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1124,23 +1124,19 @@ sd_spinup_disk(struct scsi_disk *sdkp, char *diskname)
 		/*
 		 * The device does not want the automatic start to be issued.
 		 */
-		if (sdkp->device->no_start_on_add) {
+		if (sdkp->device->no_start_on_add) 
 			break;
-		}
-
-		/*
-		 * If manual intervention is required, or this is an
-		 * absent USB storage device, a spinup is meaningless.
-		 */
-		if (sense_valid &&
-		    sshdr.sense_key == NOT_READY &&
-		    sshdr.asc == 4 && sshdr.ascq == 3) {
-			break;		/* manual intervention required */
+		if (sense_valid && sshdr.sense_key == NOT_READY) {
+			if (sshdr.asc == 4 && sshdr.ascq == 3)
+				break;	/* manual intervention required */
+			if (sshdr.asc == 4 && sshdr.ascq == 0xb)
+				break;	/* standby */
+			if (sshdr.asc == 4 && sshdr.ascq == 0xc)
+				break;	/* unavailable */
+			/*
+			 * Issue command to spin up drive when not ready
+			 */
 
-		/*
-		 * Issue command to spin up drive when not ready
-		 */
-		} else if (sense_valid && sshdr.sense_key == NOT_READY) {
 			if (!spintime) {
 				printk(KERN_NOTICE "%s: Spinning up disk...",
 				       diskname);