sr: implement sr_check_events()

Replace sr_media_change() with sr_check_events().  It normally only
uses GET_EVENT_STATUS_NOTIFICATION to check both media change and
eject request.  If @clearing includes DISK_EVENT_MEDIA_CHANGE, it
issues TUR and compares whether media presence has changed.  The SCSI
specific media change uevent is kept for compatibility.

sr_media_change() was doing both media change check and revalidation.
The revalidation part is split into sr_block_revalidate_disk().

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

3 files changed, 99 insertions, 53 deletions

diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index 310b3fac631..be6baf8ad70 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -104,14 +104,15 @@ static void sr_release(struct cdrom_device_info *);
 static void get_sectorsize(struct scsi_cd *);
 static void get_capabilities(struct scsi_cd *);
 
-static int sr_media_change(struct cdrom_device_info *, int);
+static unsigned int sr_check_events(struct cdrom_device_info *cdi,
+                                    unsigned int clearing, int slot);
 static int sr_packet(struct cdrom_device_info *, struct packet_command *);
 
 static struct cdrom_device_ops sr_dops = {
         .open                   = sr_open,
         .release                = sr_release,
         .drive_status           = sr_drive_status,
-        .media_changed          = sr_media_change,
+        .check_events           = sr_check_events,
         .tray_move              = sr_tray_move,
         .lock_door              = sr_lock_door,
         .select_speed           = sr_select_speed,
@@ -165,69 +166,96 @@ static void scsi_cd_put(struct scsi_cd *cd)
         mutex_unlock(&sr_ref_mutex);
 }
 
+static unsigned int sr_get_events(struct scsi_device *sdev)
+{
+        u8 buf[8];
+        u8 cmd[] = { GET_EVENT_STATUS_NOTIFICATION,
+                     1,                 /* polled */
+                     0, 0,              /* reserved */
+                     1 << 4,            /* notification class: media */
+                     0, 0,              /* reserved */
+                     0, sizeof(buf),    /* allocation length */
+                     0,                 /* control */
+        };
+        struct event_header *eh = (void *)buf;
+        struct media_event_desc *med = (void *)(buf + 4);
+        struct scsi_sense_hdr sshdr;
+        int result;
+
+        result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buf, sizeof(buf),
+                                  &sshdr, SR_TIMEOUT, MAX_RETRIES, NULL);
+        if (scsi_sense_valid(&sshdr) && sshdr.sense_key == UNIT_ATTENTION)
+                return DISK_EVENT_MEDIA_CHANGE;
+
+        if (result || be16_to_cpu(eh->data_len) < sizeof(*med))
+                return 0;
+
+        if (eh->nea || eh->notification_class != 0x4)
+                return 0;
+
+        if (med->media_event_code == 1)
+                return DISK_EVENT_EJECT_REQUEST;
+        else if (med->media_event_code == 2)
+                return DISK_EVENT_MEDIA_CHANGE;
+        return 0;
+}
+
 /*
- * This function checks to see if the media has been changed in the
- * CDROM drive.  It is possible that we have already sensed a change,
- * or the drive may have sensed one and not yet reported it.  We must
- * be ready for either case. This function always reports the current
- * value of the changed bit.  If flag is 0, then the changed bit is reset.
- * This function could be done as an ioctl, but we would need to have
- * an inode for that to work, and we do not always have one.
+ * This function checks to see if the media has been changed or eject
+ * button has been pressed.  It is possible that we have already
+ * sensed a change, or the drive may have sensed one and not yet
+ * reported it.  The past events are accumulated in sdev->changed and
+ * returned together with the current state.
  */
-
-static int sr_media_change(struct cdrom_device_info *cdi, int slot)
+static unsigned int sr_check_events(struct cdrom_device_info *cdi,
+                                    unsigned int clearing, int slot)
 {
         struct scsi_cd *cd = cdi->handle;
-        int retval;
-        struct scsi_sense_hdr *sshdr;
+        bool last_present;
+        struct scsi_sense_hdr sshdr;
+        unsigned int events;
+        int ret;
 
-        if (CDSL_CURRENT != slot) {
-                /* no changer support */
-                return -EINVAL;
-        }
+        /* no changer support */
+        if (CDSL_CURRENT != slot)
+                return 0;
+
+        events = sr_get_events(cd->device);
+        /*
+         * GET_EVENT_STATUS_NOTIFICATION is enough unless MEDIA_CHANGE
+         * is being cleared.  Note that there are devices which hang
+         * if asked to execute TUR repeatedly.
+         */
+        if (!(clearing & DISK_EVENT_MEDIA_CHANGE))
+                goto skip_tur;
+
+        /* let's see whether the media is there with TUR */
+        last_present = cd->media_present;
+        ret = scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr);
 
-        sshdr =  kzalloc(sizeof(*sshdr), GFP_KERNEL);
-        retval = scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES,
-                                      sshdr);
         /*
          * Media is considered to be present if TUR succeeds or fails with
          * sense data indicating something other than media-not-present
          * (ASC 0x3a).
          */
-        if (!scsi_status_is_good(retval) &&
-            (!scsi_sense_valid(sshdr) || sshdr->asc == 0x3a)) {
-                /*
-                 * Probably no media in the device.  Mark as changed, and
-                 * we will figure it out later once the drive is available
-                 * again.
-                 */
-                cd->device->changed = 1;
-                /* This will force a flush, if called from check_disk_change */
-                retval = 1;
-                goto out;
-        };
+        cd->media_present = scsi_status_is_good(ret) ||
+                (scsi_sense_valid(&sshdr) && sshdr.asc != 0x3a);
 
-        retval = cd->device->changed;
-        cd->device->changed = 0;
-        /* If the disk changed, the capacity will now be different,
-         * so we force a re-read of this information */
-        if (retval) {
-                /* check multisession offset etc */
-                sr_cd_check(cdi);
-                get_sectorsize(cd);
+        if (last_present != cd->media_present)
+                events |= DISK_EVENT_MEDIA_CHANGE;
+skip_tur:
+        if (cd->device->changed) {
+                events |= DISK_EVENT_MEDIA_CHANGE;
+                cd->device->changed = 0;
         }
 
-out:
-        /* Notify userspace, that media has changed. */
-        if (retval != cd->previous_state)
+        /* for backward compatibility */
+        if (events & DISK_EVENT_MEDIA_CHANGE)
                 sdev_evt_send_simple(cd->device, SDEV_EVT_MEDIA_CHANGE,
                                      GFP_KERNEL);
-        cd->previous_state = retval;
-        kfree(sshdr);
-
-        return retval;
+        return events;
 }
- 
+
 /*
  * sr_done is the interrupt routine for the device driver.
  *
@@ -512,10 +540,25 @@ out:
         return ret;
 }
 
-static int sr_block_media_changed(struct gendisk *disk)
+static unsigned int sr_block_check_events(struct gendisk *disk,
+                                          unsigned int clearing)
 {
         struct scsi_cd *cd = scsi_cd(disk);
-        return cdrom_media_changed(&cd->cdi);
+        return cdrom_check_events(&cd->cdi, clearing);
+}
+
+static int sr_block_revalidate_disk(struct gendisk *disk)
+{
+        struct scsi_cd *cd = scsi_cd(disk);
+        struct scsi_sense_hdr sshdr;
+
+        /* if the unit is not ready, nothing more to do */
+        if (scsi_test_unit_ready(cd->device, SR_TIMEOUT, MAX_RETRIES, &sshdr))
+                return 0;
+
+        sr_cd_check(&cd->cdi);
+        get_sectorsize(cd);
+        return 0;
 }
 
 static const struct block_device_operations sr_bdops =
@@ -524,7 +567,8 @@ static const struct block_device_operations sr_bdops =
         .open           = sr_block_open,
         .release        = sr_block_release,
         .ioctl          = sr_block_ioctl,
-        .media_changed  = sr_block_media_changed,
+        .check_events   = sr_block_check_events,
+        .revalidate_disk = sr_block_revalidate_disk,
         /* 
          * No compat_ioctl for now because sr_block_ioctl never
          * seems to pass arbitary ioctls down to host drivers.
@@ -597,6 +641,7 @@ static int sr_probe(struct device *dev)
         sprintf(disk->disk_name, "sr%d", minor);
         disk->fops = &sr_bdops;
         disk->flags = GENHD_FL_CD;
+        disk->events = DISK_EVENT_MEDIA_CHANGE | DISK_EVENT_EJECT_REQUEST;
 
         blk_queue_rq_timeout(sdev->request_queue, SR_TIMEOUT);
 
@@ -606,7 +651,7 @@ static int sr_probe(struct device *dev)
         cd->disk = disk;
         cd->capacity = 0x1fffff;
         cd->device->changed = 1;        /* force recheck CD type */
-        cd->previous_state = 1;
+        cd->media_present = 1;
         cd->use = 1;
         cd->readcd_known = 0;
         cd->readcd_cdda = 0;
diff --git a/drivers/scsi/sr.h b/drivers/scsi/sr.h
index 81fbc0b78a5..e036f1dc83c 100644
--- a/drivers/scsi/sr.h
+++ b/drivers/scsi/sr.h
@@ -40,7 +40,7 @@ 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 */
+        unsigned media_present:1;       /* media is present */
         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 */
diff --git a/include/scsi/scsi.h b/include/scsi/scsi.h
index 216af8538cc..86758618d4f 100644
--- a/include/scsi/scsi.h
+++ b/include/scsi/scsi.h
@@ -104,6 +104,7 @@ struct scsi_cmnd;
 #define UNMAP                 0x42
 #define READ_TOC              0x43
 #define READ_HEADER           0x44
+#define GET_EVENT_STATUS_NOTIFICATION 0x4a
 #define LOG_SELECT            0x4c
 #define LOG_SENSE             0x4d
 #define XDWRITEREAD_10        0x53