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Message-ID: <Pine.LNX.4.44L0.0607281633100.5679-100000@iolanthe.rowland.org>
Date: Fri, 28 Jul 2006 16:50:09 -0400 (EDT)
From: Alan Stern <stern@...land.harvard.edu>
To: Andrew Morton <akpm@...l.org>
cc: James Bottomley <James.Bottomley@...elEye.com>,
Jens Axboe <axboe@...e.de>,
Kernel development list <linux-kernel@...r.kernel.org>
Subject: [PATCH] SCSI: early detection of medium not present, updated
This patch (as757) is meant to apply on top of the
scsi-core-and-sd-early-detection-of-medium-not-present patch currently in
2.6.18-rc2-mm1. It updates the way the scsi_test_unit_ready() routine
reports medium not present, using the technique recommended by James
Bottomley.
Signed-off-by: Alan Stern <stern@...land.harvard.edu>
---
If James would prefer, I could submit this in a different form: first
revert the earlier SCSI patch and then add the new stuff from this one.
In a brief conversation during OLS, Jens said that he saw no problem with
allowing the block layer to accept -ENOMEDIUM as a return code from the
media_changed method. The patch is already in -mm, named
block-layer-early-detection-of-medium-not-present.
In principle cdrom drivers could use a similar technique to avoid calling
the revalidate method when no disc is loaded, but that would require more
far-reaching changes. For now it's easier to confine this to disk drives.
Index: 2.6.18-rc2-mm1/drivers/scsi/sd.c
===================================================================
--- 2.6.18-rc2-mm1.orig/drivers/scsi/sd.c
+++ 2.6.18-rc2-mm1/drivers/scsi/sd.c
@@ -733,6 +733,7 @@ static int sd_media_changed(struct gendi
struct scsi_disk *sdkp = scsi_disk(disk);
struct scsi_device *sdp = sdkp->device;
int retval;
+ int media_not_present = 0;
SCSI_LOG_HLQUEUE(3, printk("sd_media_changed: disk=%s\n",
disk->disk_name));
@@ -760,7 +761,8 @@ static int sd_media_changed(struct gendi
*/
retval = -ENODEV;
if (scsi_block_when_processing_errors(sdp))
- retval = scsi_test_unit_ready(sdp, SD_TIMEOUT, SD_MAX_RETRIES);
+ retval = scsi_test_unit_ready(sdp, SD_TIMEOUT, SD_MAX_RETRIES,
+ &media_not_present);
/*
* Unable to test, unit probably not ready. This usually
@@ -768,7 +770,7 @@ static int sd_media_changed(struct gendi
* and we will figure it out later once the drive is
* available again.
*/
- if (retval || sdp->medium_not_present)
+ if (retval || media_not_present)
goto not_present;
/*
* For removable scsi disk we have to recognise the presence
Index: 2.6.18-rc2-mm1/include/scsi/scsi_device.h
===================================================================
--- 2.6.18-rc2-mm1.orig/include/scsi/scsi_device.h
+++ 2.6.18-rc2-mm1/include/scsi/scsi_device.h
@@ -92,7 +92,6 @@ struct scsi_device {
unsigned writeable:1;
unsigned removable:1;
unsigned changed:1; /* Data invalid due to media change */
- unsigned medium_not_present:1; /* Set by scsi_test_unit_ready() */
unsigned busy:1; /* Used to prevent races */
unsigned lockable:1; /* Able to prevent media removal */
unsigned locked:1; /* Media removal disabled */
@@ -268,7 +267,7 @@ extern int scsi_mode_select(struct scsi_
struct scsi_mode_data *data,
struct scsi_sense_hdr *);
extern int scsi_test_unit_ready(struct scsi_device *sdev, int timeout,
- int retries);
+ int retries, int *media_not_present);
extern int scsi_device_set_state(struct scsi_device *sdev,
enum scsi_device_state state);
extern int scsi_device_quiesce(struct scsi_device *sdev);
Index: 2.6.18-rc2-mm1/drivers/scsi/sr.c
===================================================================
--- 2.6.18-rc2-mm1.orig/drivers/scsi/sr.c
+++ 2.6.18-rc2-mm1/drivers/scsi/sr.c
@@ -178,14 +178,16 @@ static int sr_media_change(struct cdrom_
{
struct scsi_cd *cd = cdi->handle;
int retval;
+ int media_not_present = 0;
if (CDSL_CURRENT != slot) {
/* no changer support */
return -EINVAL;
}
- retval = scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES);
- if (retval) {
+ retval = scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES,
+ &media_not_present);
+ if (retval || media_not_present) {
/* Unable to test, unit probably not ready. This usually
* means there is no disc in the drive. Mark as changed,
* and we will figure it out later once the drive is
Index: 2.6.18-rc2-mm1/drivers/scsi/scsi_lib.c
===================================================================
--- 2.6.18-rc2-mm1.orig/drivers/scsi/scsi_lib.c
+++ 2.6.18-rc2-mm1/drivers/scsi/scsi_lib.c
@@ -1867,7 +1867,8 @@ scsi_mode_sense(struct scsi_device *sdev
EXPORT_SYMBOL(scsi_mode_sense);
int
-scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries)
+scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
+ int *media_not_present)
{
char cmd[] = {
TEST_UNIT_READY, 0, 0, 0, 0, 0,
@@ -1878,7 +1879,6 @@ scsi_test_unit_ready(struct scsi_device
result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, &sshdr,
timeout, retries);
- sdev->medium_not_present = 0;
if ((driver_byte(result) & DRIVER_SENSE) && sdev->removable) {
if ((scsi_sense_valid(&sshdr)) &&
@@ -1887,8 +1887,8 @@ scsi_test_unit_ready(struct scsi_device
sdev->changed = 1;
result = 0;
- if (sshdr.asc == 0x3A)
- sdev->medium_not_present = 1;
+ if (sshdr.asc == 0x3A && media_not_present != NULL)
+ *media_not_present = 1;
}
}
return result;
Index: 2.6.18-rc2-mm1/drivers/scsi/scsi_ioctl.c
===================================================================
--- 2.6.18-rc2-mm1.orig/drivers/scsi/scsi_ioctl.c
+++ 2.6.18-rc2-mm1/drivers/scsi/scsi_ioctl.c
@@ -242,7 +242,7 @@ int scsi_ioctl(struct scsi_device *sdev,
return scsi_set_medium_removal(sdev, SCSI_REMOVAL_ALLOW);
case SCSI_IOCTL_TEST_UNIT_READY:
return scsi_test_unit_ready(sdev, IOCTL_NORMAL_TIMEOUT,
- NORMAL_RETRIES);
+ NORMAL_RETRIES, NULL);
case SCSI_IOCTL_START_UNIT:
scsi_cmd[0] = START_STOP;
scsi_cmd[1] = 0;
-
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