Re: Fw: SCSI device not spinning up on rw

[Brian King <brking@us.ibm.com>]

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Brian King wrote:
> Douglas Gilbert wrote:
>>> I have a SCSI disk, which I want to spin down when the system is not in
>>> use. I do this by using sdparm, scsi-spin or sg-utils. These tools all
>>> spin down the SCSI drive by using an IOCTL.
>>>
>>> Problem is that the kernel doesn't spin the drive back up. When a
>>> process requests data from the disk (a simple ls), the kernel responds
>>> with an I/O error. After some of these errors, reiserfs marks the drive
>>> read-only.
> 
> Setting sdev->allow_restart in struct scsi_device will cause sense
> key/code/qual of 02/04/02 (not ready, initialization command required)
> to wake up the scsi error handler and will force scsi core to issue
> a start unit command to the disk. I added this a while back to handle
> ipr raid arrays which need a start unit command each time the adapter
> gets reset. It would be easy enough for sd to use this, either
> all the time, or only when directed to, or we could add a sysfs attribute
> to the disk to enable/disable this behavior.

Please try the attached patch. It adds a sysfs device attribute "allow_restart".
If you set it to 1, then scsi core will issue a start unit when it sees 02/04/02
sense data. The attribute is in the same place as the FUA and cache_type
attributes (eg. /sys/block/sdc/device/scsi_disk:1:1:9:0/allow_restart). 


-- 
Brian King
eServer Storage I/O
IBM Linux Technology Center

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Signed-off-by: Brian King <brking@us.ibm.com>
---

 linux-2.6-bjking1/drivers/scsi/sd.c |   26 ++++++++++++++++++++++++++
 1 files changed, 26 insertions(+)

diff -puN drivers/scsi/sd.c~sd_allow_restart_sysfs_attr drivers/scsi/sd.c
--- linux-2.6/drivers/scsi/sd.c~sd_allow_restart_sysfs_attr	2006-06-05 12:33:06.000000000 -0500
+++ linux-2.6-bjking1/drivers/scsi/sd.c	2006-06-05 12:34:22.000000000 -0500
@@ -208,6 +208,23 @@ static ssize_t sd_store_cache_type(struc
 	return count;
 }
 
+static ssize_t sd_store_allow_restart(struct class_device *cdev, const char *buf,
+				      size_t count)
+{
+	struct scsi_disk *sdkp = to_scsi_disk(cdev);
+	struct scsi_device *sdp = sdkp->device;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	if (sdp->type != TYPE_DISK)
+		return -EINVAL;
+
+	sdp->allow_restart = simple_strtoul(buf, NULL, 10);
+
+	return count;
+}
+
 static ssize_t sd_show_cache_type(struct class_device *cdev, char *buf)
 {
 	struct scsi_disk *sdkp = to_scsi_disk(cdev);
@@ -223,10 +240,19 @@ static ssize_t sd_show_fua(struct class_
 	return snprintf(buf, 20, "%u\n", sdkp->DPOFUA);
 }
 
+static ssize_t sd_show_allow_restart(struct class_device *cdev, char *buf)
+{
+	struct scsi_disk *sdkp = to_scsi_disk(cdev);
+
+	return snprintf(buf, 40, "%d\n", sdkp->device->allow_restart);
+}
+
 static struct class_device_attribute sd_disk_attrs[] = {
 	__ATTR(cache_type, S_IRUGO|S_IWUSR, sd_show_cache_type,
 	       sd_store_cache_type),
 	__ATTR(FUA, S_IRUGO, sd_show_fua, NULL),
+	__ATTR(allow_restart, S_IRUGO|S_IWUSR, sd_show_allow_restart,
+	       sd_store_allow_restart),
 	__ATTR_NULL,
 };
 
_