scsi: disable automatic target scan
On larger installations it is useful to disable automatic LUN scanning,
and only add the required LUNs via udev rules. This can speed up bootup
dramatically.
This patch introduces a new scan module parameter value 'manual', which
works like 'none', but can be overridden by setting the 'rescan' value
from scsi_scan_target to 'SCSI_SCAN_MANUAL'. And it updates all
relevant callers to set the 'rescan' value to 'SCSI_SCAN_MANUAL' if
invoked via the 'scan' option in sysfs.
Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Tested-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 97074c9..6c8ad36 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -96,10 +96,13 @@
#define SCSI_SCAN_TYPE_DEFAULT "sync"
#endif
-char scsi_scan_type[6] = SCSI_SCAN_TYPE_DEFAULT;
+char scsi_scan_type[7] = SCSI_SCAN_TYPE_DEFAULT;
-module_param_string(scan, scsi_scan_type, sizeof(scsi_scan_type), S_IRUGO);
-MODULE_PARM_DESC(scan, "sync, async or none");
+module_param_string(scan, scsi_scan_type, sizeof(scsi_scan_type),
+ S_IRUGO|S_IWUSR);
+MODULE_PARM_DESC(scan, "sync, async, manual, or none. "
+ "Setting to 'manual' disables automatic scanning, but allows "
+ "for manual device scan via the 'scan' sysfs attribute.");
static unsigned int scsi_inq_timeout = SCSI_TIMEOUT/HZ + 18;
@@ -1040,7 +1043,8 @@
* @lun: LUN of target device
* @bflagsp: store bflags here if not NULL
* @sdevp: probe the LUN corresponding to this scsi_device
- * @rescan: if nonzero skip some code only needed on first scan
+ * @rescan: if not equal to SCSI_SCAN_INITIAL skip some code only
+ * needed on first scan
* @hostdata: passed to scsi_alloc_sdev()
*
* Description:
@@ -1055,7 +1059,8 @@
**/
static int scsi_probe_and_add_lun(struct scsi_target *starget,
u64 lun, int *bflagsp,
- struct scsi_device **sdevp, int rescan,
+ struct scsi_device **sdevp,
+ enum scsi_scan_mode rescan,
void *hostdata)
{
struct scsi_device *sdev;
@@ -1069,7 +1074,7 @@
*/
sdev = scsi_device_lookup_by_target(starget, lun);
if (sdev) {
- if (rescan || !scsi_device_created(sdev)) {
+ if (rescan != SCSI_SCAN_INITIAL || !scsi_device_created(sdev)) {
SCSI_LOG_SCAN_BUS(3, sdev_printk(KERN_INFO, sdev,
"scsi scan: device exists on %s\n",
dev_name(&sdev->sdev_gendev)));
@@ -1205,7 +1210,8 @@
* Modifies sdevscan->lun.
**/
static void scsi_sequential_lun_scan(struct scsi_target *starget,
- int bflags, int scsi_level, int rescan)
+ int bflags, int scsi_level,
+ enum scsi_scan_mode rescan)
{
uint max_dev_lun;
u64 sparse_lun, lun;
@@ -1300,7 +1306,7 @@
* 1: could not scan with REPORT LUN
**/
static int scsi_report_lun_scan(struct scsi_target *starget, int bflags,
- int rescan)
+ enum scsi_scan_mode rescan)
{
char devname[64];
unsigned char scsi_cmd[MAX_COMMAND_SIZE];
@@ -1546,7 +1552,7 @@
EXPORT_SYMBOL(scsi_rescan_device);
static void __scsi_scan_target(struct device *parent, unsigned int channel,
- unsigned int id, u64 lun, int rescan)
+ unsigned int id, u64 lun, enum scsi_scan_mode rescan)
{
struct Scsi_Host *shost = dev_to_shost(parent);
int bflags = 0;
@@ -1604,7 +1610,10 @@
* @channel: channel to scan
* @id: target id to scan
* @lun: Specific LUN to scan or SCAN_WILD_CARD
- * @rescan: passed to LUN scanning routines
+ * @rescan: passed to LUN scanning routines; SCSI_SCAN_INITIAL for
+ * no rescan, SCSI_SCAN_RESCAN to rescan existing LUNs,
+ * and SCSI_SCAN_MANUAL to force scanning even if
+ * 'scan=manual' is set.
*
* Description:
* Scan the target id on @parent, @channel, and @id. Scan at least LUN 0,
@@ -1614,13 +1623,17 @@
* sequential scan of LUNs on the target id.
**/
void scsi_scan_target(struct device *parent, unsigned int channel,
- unsigned int id, u64 lun, int rescan)
+ unsigned int id, u64 lun, enum scsi_scan_mode rescan)
{
struct Scsi_Host *shost = dev_to_shost(parent);
if (strncmp(scsi_scan_type, "none", 4) == 0)
return;
+ if (rescan != SCSI_SCAN_MANUAL &&
+ strncmp(scsi_scan_type, "manual", 6) == 0)
+ return;
+
mutex_lock(&shost->scan_mutex);
if (!shost->async_scan)
scsi_complete_async_scans();
@@ -1634,7 +1647,8 @@
EXPORT_SYMBOL(scsi_scan_target);
static void scsi_scan_channel(struct Scsi_Host *shost, unsigned int channel,
- unsigned int id, u64 lun, int rescan)
+ unsigned int id, u64 lun,
+ enum scsi_scan_mode rescan)
{
uint order_id;
@@ -1665,7 +1679,8 @@
}
int scsi_scan_host_selected(struct Scsi_Host *shost, unsigned int channel,
- unsigned int id, u64 lun, int rescan)
+ unsigned int id, u64 lun,
+ enum scsi_scan_mode rescan)
{
SCSI_LOG_SCAN_BUS(3, shost_printk (KERN_INFO, shost,
"%s: <%u:%u:%llu>\n",
@@ -1844,7 +1859,8 @@
{
struct async_scan_data *data;
- if (strncmp(scsi_scan_type, "none", 4) == 0)
+ if (strncmp(scsi_scan_type, "none", 4) == 0 ||
+ strncmp(scsi_scan_type, "manual", 6) == 0)
return;
if (scsi_autopm_get_host(shost) < 0)
return;
