[PATCHv3] scsi: disable automatic target scan

[Hannes Reinecke <hare@suse.de>]

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 overriden 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>
---
 drivers/infiniband/ulp/srp/ib_srp.c |  2 +-
 drivers/message/fusion/mptspi.c     |  2 +-
 drivers/s390/scsi/zfcp_unit.c       |  3 ++-
 drivers/scsi/scsi_priv.h            |  2 +-
 drivers/scsi/scsi_proc.c            |  3 ++-
 drivers/scsi/scsi_scan.c            | 44 +++++++++++++++++++++++++------------
 drivers/scsi/scsi_sysfs.c           |  3 ++-
 drivers/scsi/scsi_transport_fc.c    |  6 +++--
 drivers/scsi/scsi_transport_iscsi.c |  5 ++++-
 drivers/scsi/scsi_transport_sas.c   |  7 +++---
 drivers/scsi/snic/snic_disc.c       |  2 +-
 include/scsi/scsi_device.h          |  9 +++++++-
 12 files changed, 60 insertions(+), 28 deletions(-)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 03022f6..1f97381 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -2851,7 +2851,7 @@ static int srp_add_target(struct srp_host *host, struct srp_target_port *target)
 	spin_unlock(&host->target_lock);
 
 	scsi_scan_target(&target->scsi_host->shost_gendev,
-			 0, target->scsi_id, SCAN_WILD_CARD, 0);
+			 0, target->scsi_id, SCAN_WILD_CARD, SCSI_SCAN_INITIAL);
 
 	if (srp_connected_ch(target) < target->ch_count ||
 	    target->qp_in_error) {
diff --git a/drivers/message/fusion/mptspi.c b/drivers/message/fusion/mptspi.c
index 613231c..031e088 100644
--- a/drivers/message/fusion/mptspi.c
+++ b/drivers/message/fusion/mptspi.c
@@ -1150,7 +1150,7 @@ static void mpt_work_wrapper(struct work_struct *work)
 	}
 	shost_printk(KERN_INFO, shost, MYIOC_s_FMT
 	    "Integrated RAID detects new device %d\n", ioc->name, disk);
-	scsi_scan_target(&ioc->sh->shost_gendev, 1, disk, 0, 1);
+	scsi_scan_target(&ioc->sh->shost_gendev, 1, disk, 0, SCSI_SCAN_RESCAN);
 }
 
 
diff --git a/drivers/s390/scsi/zfcp_unit.c b/drivers/s390/scsi/zfcp_unit.c
index 157d3d2..08bba7c 100644
--- a/drivers/s390/scsi/zfcp_unit.c
+++ b/drivers/s390/scsi/zfcp_unit.c
@@ -26,7 +26,8 @@ void zfcp_unit_scsi_scan(struct zfcp_unit *unit)
 	lun = scsilun_to_int((struct scsi_lun *) &unit->fcp_lun);
 
 	if (rport && rport->port_state == FC_PORTSTATE_ONLINE)
-		scsi_scan_target(&rport->dev, 0, rport->scsi_target_id, lun, 1);
+		scsi_scan_target(&rport->dev, 0, rport->scsi_target_id, lun,
+				 SCSI_SCAN_RESCAN);
 }
 
 static void zfcp_unit_scsi_scan_work(struct work_struct *work)
diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
index 27b4d0a..57a4b99 100644
--- a/drivers/scsi/scsi_priv.h
+++ b/drivers/scsi/scsi_priv.h
@@ -116,7 +116,7 @@ extern void scsi_exit_procfs(void);
 extern char scsi_scan_type[];
 extern int scsi_complete_async_scans(void);
 extern int scsi_scan_host_selected(struct Scsi_Host *, unsigned int,
-				   unsigned int, u64, int);
+				   unsigned int, u64, enum scsi_scan_mode);
 extern void scsi_forget_host(struct Scsi_Host *);
 extern void scsi_rescan_device(struct device *);
 
diff --git a/drivers/scsi/scsi_proc.c b/drivers/scsi/scsi_proc.c
index 251598e..7a74b82 100644
--- a/drivers/scsi/scsi_proc.c
+++ b/drivers/scsi/scsi_proc.c
@@ -251,7 +251,8 @@ static int scsi_add_single_device(uint host, uint channel, uint id, uint lun)
 	if (shost->transportt->user_scan)
 		error = shost->transportt->user_scan(shost, channel, id, lun);
 	else
-		error = scsi_scan_host_selected(shost, channel, id, lun, 1);
+		error = scsi_scan_host_selected(shost, channel, id, lun,
+						SCSI_SCAN_MANUAL);
 	scsi_host_put(shost);
 	return error;
 }
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 @@ MODULE_PARM_DESC(max_luns,
 #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 @@ static unsigned char *scsi_inq_str(unsigned char *buf, unsigned char *inq,
  * @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 unsigned char *scsi_inq_str(unsigned char *buf, unsigned char *inq,
  **/
 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 @@ static int scsi_probe_and_add_lun(struct scsi_target *starget,
 	 */
 	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 @@ static int scsi_probe_and_add_lun(struct scsi_target *starget,
  *     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 @@ static void scsi_sequential_lun_scan(struct scsi_target *starget,
  *     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 @@ void scsi_rescan_device(struct device *dev)
 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 @@ static void __scsi_scan_target(struct device *parent, unsigned int channel,
  * @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 @@ static void __scsi_scan_target(struct device *parent, unsigned int channel,
  *     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 @@ void scsi_scan_target(struct device *parent, unsigned int channel,
 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 @@ static void scsi_scan_channel(struct Scsi_Host *shost, unsigned int channel,
 }
 
 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 @@ void scsi_scan_host(struct Scsi_Host *shost)
 {
 	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;
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index 92ffd24..3b2045f 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -143,7 +143,8 @@ static int scsi_scan(struct Scsi_Host *shost, const char *str)
 	if (shost->transportt->user_scan)
 		res = shost->transportt->user_scan(shost, channel, id, lun);
 	else
-		res = scsi_scan_host_selected(shost, channel, id, lun, 1);
+		res = scsi_scan_host_selected(shost, channel, id, lun,
+					      SCSI_SCAN_MANUAL);
 	return res;
 }
 
diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
index 8a88226..bf28c68 100644
--- a/drivers/scsi/scsi_transport_fc.c
+++ b/drivers/scsi/scsi_transport_fc.c
@@ -2110,7 +2110,8 @@ fc_user_scan_tgt(struct Scsi_Host *shost, uint channel, uint id, u64 lun)
 		if ((channel == rport->channel) &&
 		    (id == rport->scsi_target_id)) {
 			spin_unlock_irqrestore(shost->host_lock, flags);
-			scsi_scan_target(&rport->dev, channel, id, lun, 1);
+			scsi_scan_target(&rport->dev, channel, id, lun,
+					 SCSI_SCAN_MANUAL);
 			return;
 		}
 	}
@@ -3277,7 +3278,8 @@ fc_scsi_scan_rport(struct work_struct *work)
 	    (rport->roles & FC_PORT_ROLE_FCP_TARGET) &&
 	    !(i->f->disable_target_scan)) {
 		scsi_scan_target(&rport->dev, rport->channel,
-			rport->scsi_target_id, SCAN_WILD_CARD, 1);
+				 rport->scsi_target_id, SCAN_WILD_CARD,
+				 SCSI_SCAN_RESCAN);
 	}
 
 	spin_lock_irqsave(shost->host_lock, flags);
diff --git a/drivers/scsi/scsi_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index 4414816..7a759a9 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -1783,6 +1783,7 @@ struct iscsi_scan_data {
 	unsigned int channel;
 	unsigned int id;
 	u64 lun;
+	enum scsi_scan_mode rescan;
 };
 
 static int iscsi_user_scan_session(struct device *dev, void *data)
@@ -1819,7 +1820,7 @@ static int iscsi_user_scan_session(struct device *dev, void *data)
 		    (scan_data->id == SCAN_WILD_CARD ||
 		     scan_data->id == id))
 			scsi_scan_target(&session->dev, 0, id,
-					 scan_data->lun, 1);
+					 scan_data->lun, scan_data->rescan);
 	}
 
 user_scan_exit:
@@ -1836,6 +1837,7 @@ static int iscsi_user_scan(struct Scsi_Host *shost, uint channel,
 	scan_data.channel = channel;
 	scan_data.id = id;
 	scan_data.lun = lun;
+	scan_data.rescan = SCSI_SCAN_MANUAL;
 
 	return device_for_each_child(&shost->shost_gendev, &scan_data,
 				     iscsi_user_scan_session);
@@ -1852,6 +1854,7 @@ static void iscsi_scan_session(struct work_struct *work)
 	scan_data.channel = 0;
 	scan_data.id = SCAN_WILD_CARD;
 	scan_data.lun = SCAN_WILD_CARD;
+	scan_data.rescan = SCSI_SCAN_RESCAN;
 
 	iscsi_user_scan_session(&session->dev, &scan_data);
 	atomic_dec(&ihost->nr_scans);
diff --git a/drivers/scsi/scsi_transport_sas.c b/drivers/scsi/scsi_transport_sas.c
index b6f958193..3f0ff07 100644
--- a/drivers/scsi/scsi_transport_sas.c
+++ b/drivers/scsi/scsi_transport_sas.c
@@ -1614,7 +1614,8 @@ int sas_rphy_add(struct sas_rphy *rphy)
 		else
 			lun = 0;
 
-		scsi_scan_target(&rphy->dev, 0, rphy->scsi_target_id, lun, 0);
+		scsi_scan_target(&rphy->dev, 0, rphy->scsi_target_id, lun,
+				 SCSI_SCAN_INITIAL);
 	}
 
 	return 0;
@@ -1739,8 +1740,8 @@ static int sas_user_scan(struct Scsi_Host *shost, uint channel,
 
 		if ((channel == SCAN_WILD_CARD || channel == 0) &&
 		    (id == SCAN_WILD_CARD || id == rphy->scsi_target_id)) {
-			scsi_scan_target(&rphy->dev, 0,
-					 rphy->scsi_target_id, lun, 1);
+			scsi_scan_target(&rphy->dev, 0, rphy->scsi_target_id,
+					 lun, SCSI_SCAN_MANUAL);
 		}
 	}
 	mutex_unlock(&sas_host->lock);
diff --git a/drivers/scsi/snic/snic_disc.c b/drivers/scsi/snic/snic_disc.c
index 5f63217..5f48795 100644
--- a/drivers/scsi/snic/snic_disc.c
+++ b/drivers/scsi/snic/snic_disc.c
@@ -171,7 +171,7 @@ snic_scsi_scan_tgt(struct work_struct *work)
 			 tgt->channel,
 			 tgt->scsi_tgt_id,
 			 SCAN_WILD_CARD,
-			 1);
+			 SCSI_SCAN_RESCAN);
 
 	spin_lock_irqsave(shost->host_lock, flags);
 	tgt->flags &= ~SNIC_TGT_SCAN_PENDING;
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index c067019..61341d3 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -50,6 +50,12 @@ enum scsi_device_state {
 	SDEV_CREATED_BLOCK,	/* same as above but for created devices */
 };
 
+enum scsi_scan_mode {
+	SCSI_SCAN_INITIAL = 0,
+	SCSI_SCAN_RESCAN,
+	SCSI_SCAN_MANUAL,
+};
+
 enum scsi_device_event {
 	SDEV_EVT_MEDIA_CHANGE	= 1,	/* media has changed */
 	SDEV_EVT_INQUIRY_CHANGE_REPORTED,		/* 3F 03  UA reported */
@@ -391,7 +397,8 @@ extern void scsi_device_resume(struct scsi_device *sdev);
 extern void scsi_target_quiesce(struct scsi_target *);
 extern void scsi_target_resume(struct scsi_target *);
 extern 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);
 extern void scsi_target_reap(struct scsi_target *);
 extern void scsi_target_block(struct device *);
 extern void scsi_target_unblock(struct device *, enum scsi_device_state);
-- 
1.8.5.6