[SCSI] sr,sd: send media state change modification events

This will send for a card reader slot (remove/add media):
  UEVENT[1187091572.155884] change   /devices/pci0000:00/0000:00:1d.7/usb5/5-2/5-2:1.0/host7/target7:0:0/7:0:0:0 (scsi)
  UEVENT[1187091572.162314] remove   /block/sdb/sdb1 (block)
  UEVENT[1187091572.172464] add      /block/sdb/sdb1 (block)
  UEVENT[1187091572.175408] change   /devices/pci0000:00/0000:00:1d.7/usb5/5-2/5-2:1.0/host7/target7:0:0/7:0:0:0 (scsi)

and for a DVD drive (add/eject media):
  UEVENT[1187091590.189159] change   /devices/pci0000:00/0000:00:1f.1/host4/target4:0:0/4:0:0:0 (scsi)
  UEVENT[1187091590.957124] add      /module/isofs (module)
  UEVENT[1187091604.468207] change   /devices/pci0000:00/0000:00:1f.1/host4/target4:0:0/4:0:0:0 (scsi)

Userspace gets events, even for unpartitioned media. This unifies
the event handling for asynchronoous events (AN) and events caused by
perodical polling the device from userspace.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>

[jejb: modified for new event API]
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/sd.c

@@ -749,8 +749,11 @@ static int sd_media_changed(struct gendisk *disk)
 	 * can deal with it then.  It is only because of unrecoverable errors
 	 * that we would ever take a device offline in the first place.
 	 */
-	if (!scsi_device_online(sdp))
-		goto not_present;
+	if (!scsi_device_online(sdp)) {
+		set_media_not_present(sdkp);
+		retval = 1;
+		goto out;
+	}
 
 	/*
 	 * Using TEST_UNIT_READY enables differentiation between drive with
@@ -762,6 +765,7 @@ static int sd_media_changed(struct gendisk *disk)
 	 * sd_revalidate() is called.
 	 */
 	retval = -ENODEV;
+
 	if (scsi_block_when_processing_errors(sdp))
 		retval = scsi_test_unit_ready(sdp, SD_TIMEOUT, SD_MAX_RETRIES);
 
@@ -771,8 +775,11 @@ static int sd_media_changed(struct gendisk *disk)
 	 * and we will figure it out later once the drive is
 	 * available again.
 	 */
-	if (retval)
-		 goto not_present;
+	if (retval) {
+		set_media_not_present(sdkp);
+		retval = 1;
+		goto out;
+	}
 
 	/*
 	 * For removable scsi disk we have to recognise the presence
@@ -783,12 +790,11 @@ static int sd_media_changed(struct gendisk *disk)
 
 	retval = sdp->changed;
 	sdp->changed = 0;
-
+out:
+	if (retval != sdkp->previous_state)
+		sdev_evt_send_simple(sdp, SDEV_EVT_MEDIA_CHANGE, GFP_KERNEL);
+	sdkp->previous_state = retval;
 	return retval;
-
-not_present:
-	set_media_not_present(sdkp);
-	return 1;
 }
 
 static int sd_sync_cache(struct scsi_disk *sdkp)

drivers/scsi/sr.c

@@ -192,8 +192,9 @@ static int sr_media_change(struct cdrom_device_info *cdi, int slot)
 		 * and we will figure it out later once the drive is
 		 * available again.  */
 		cd->device->changed = 1;
-		return 1;	/* This will force a flush, if called from
-				 * check_disk_change */
+		/* This will force a flush, if called from check_disk_change */
+		retval = 1;
+		goto out;
 	};
 
 	retval = cd->device->changed;
@@ -203,9 +204,16 @@ static int sr_media_change(struct cdrom_device_info *cdi, int slot)
 	if (retval) {
 		/* check multisession offset etc */
 		sr_cd_check(cdi);
-
 		get_sectorsize(cd);
 	}
+
+out:
+	/* Notify userspace, that media has changed. */
+	if (retval != cd->previous_state)
+		sdev_evt_send_simple(cd->device, SDEV_EVT_MEDIA_CHANGE,
+				     GFP_KERNEL);
+	cd->previous_state = retval;
+
 	return retval;
 }
  

drivers/scsi/sr.h

@@ -37,6 +37,7 @@ typedef struct scsi_cd {
 	unsigned xa_flag:1;	/* CD has XA sectors ? */
 	unsigned readcd_known:1;	/* drive supports READ_CD (0xbe) */
 	unsigned readcd_cdda:1;	/* reading audio data using READ_CD */
+	unsigned previous_state:1;	/* media has changed */
 	struct cdrom_device_info cdi;
 	/* We hold gendisk and scsi_device references on probe and use
 	 * the refs on this kref to decide when to release them */

include/scsi/sd.h

@@ -41,6 +41,7 @@ struct scsi_disk {
 	u32		index;
 	u8		media_present;
 	u8		write_prot;
+	unsigned	previous_state : 1;
 	unsigned	WCE : 1;	/* state of disk WCE bit */
 	unsigned	RCD : 1;	/* state of disk RCD bit, unused */
 	unsigned	DPOFUA : 1;	/* state of disk DPOFUA bit */