block: don't block events on excl write for non-optical devices

Disk event code automatically blocks events on excl write.  This is
primarily to avoid issuing polling commands while burning is in
progress.  This behavior doesn't fit other types of devices with
removeable media where polling commands don't have adverse side
effects and door locking usually doesn't exist.

This patch introduces new genhd flag which controls the auto-blocking
behavior and uses it to enable auto-blocking only on optical devices.

Note for stable: 2.6.38 and later only

Cc: [email protected]
Signed-off-by: Tejun Heo <[email protected]>
Reported-by: Kay Sievers <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

diff --git a/drivers/block/paride/pcd.c b/drivers/block/paride/pcd.c
index 2f2ccf6862519c4bb44493ccab140cbbdab37a93..a0aabd904a51294605a20e39de391660bff77e90 100644 (file)
--- a/drivers/block/paride/pcd.c
+++ b/drivers/block/paride/pcd.c
@@ -320,6 +320,7 @@ static void pcd_init_units(void)
                disk->first_minor = unit;
                strcpy(disk->disk_name, cd->name);      /* umm... */
                disk->fops = &pcd_bdops;
+               disk->flags = GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE;
                disk->events = DISK_EVENT_MEDIA_CHANGE;
        }
 }

diff --git a/drivers/cdrom/viocd.c b/drivers/cdrom/viocd.c
index 4e874c5fa60595036a7e10b26257384715b06b56..ae15a4ddaa9b0a3d7ff172e737dbaafd9fe8ac46 100644 (file)
--- a/drivers/cdrom/viocd.c
+++ b/drivers/cdrom/viocd.c
@@ -625,7 +625,8 @@ static int viocd_probe(struct vio_dev *vdev, const struct vio_device_id *id)
        blk_queue_max_hw_sectors(q, 4096 / 512);
        gendisk->queue = q;
        gendisk->fops = &viocd_fops;
-       gendisk->flags = GENHD_FL_CD|GENHD_FL_REMOVABLE;
+       gendisk->flags = GENHD_FL_CD | GENHD_FL_REMOVABLE |
+                        GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE;
        gendisk->events = DISK_EVENT_MEDIA_CHANGE;
        set_capacity(gendisk, 0);
        gendisk->private_data = d;

diff --git a/drivers/ide/ide-cd.c b/drivers/ide/ide-cd.c
index fd1e117991373853d5b51d8827f99157fabd3b55..6e5123b1d341746341d9c3feda2ad445606c327c 100644 (file)
--- a/drivers/ide/ide-cd.c
+++ b/drivers/ide/ide-cd.c
@@ -1781,7 +1781,7 @@ static int ide_cd_probe(ide_drive_t *drive)
 
        ide_cd_read_toc(drive, &sense);
        g->fops = &idecd_ops;
-       g->flags |= GENHD_FL_REMOVABLE;
+       g->flags |= GENHD_FL_REMOVABLE | GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE;
        g->events = DISK_EVENT_MEDIA_CHANGE;
        add_disk(g);
        return 0;

diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index 95019c747cc17cad69ed22c9091c2228b914c23b..4778e27071689593ec4fdffdd1107018c2f7ebe6 100644 (file)
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -636,7 +636,7 @@ static int sr_probe(struct device *dev)
        disk->first_minor = minor;
        sprintf(disk->disk_name, "sr%d", minor);
        disk->fops = &sr_bdops;
-       disk->flags = GENHD_FL_CD;
+       disk->flags = GENHD_FL_CD | GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE;
        disk->events = DISK_EVENT_MEDIA_CHANGE | DISK_EVENT_EJECT_REQUEST;
 
        blk_queue_rq_timeout(sdev->request_queue, SR_TIMEOUT);

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 257b00e9842808721780d1af1c09aa2f35558d35..d7c2e0fddc6f231cb4734af8355a54f846d78660 100644 (file)
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1237,6 +1237,8 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
        res = __blkdev_get(bdev, mode, 0);
 
        if (whole) {
+               struct gendisk *disk = whole->bd_disk;
+
                /* finish claiming */
                mutex_lock(&bdev->bd_mutex);
                spin_lock(&bdev_lock);
@@ -1263,15 +1265,16 @@ int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder)
                spin_unlock(&bdev_lock);
 
                /*
-                * Block event polling for write claims.  Any write
-                * holder makes the write_holder state stick until all
-                * are released.  This is good enough and tracking
-                * individual writeable reference is too fragile given
-                * the way @mode is used in blkdev_get/put().
+                * Block event polling for write claims if requested.  Any
+                * write holder makes the write_holder state stick until
+                * all are released.  This is good enough and tracking
+                * individual writeable reference is too fragile given the
+                * way @mode is used in blkdev_get/put().
                 */
-               if (!res && (mode & FMODE_WRITE) && !bdev->bd_write_holder) {
+               if ((disk->flags & GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE) &&
+                   !res && (mode & FMODE_WRITE) && !bdev->bd_write_holder) {
                        bdev->bd_write_holder = true;
-                       disk_block_events(bdev->bd_disk);
+                       disk_block_events(disk);
                }
 
                mutex_unlock(&bdev->bd_mutex);

diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index d764a426e9fdbf5b5086542e3eeb6c6a2e6d3c8a..300d7582006e49f6ea08a3df09fc9070748c5256 100644 (file)
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -127,6 +127,7 @@ struct hd_struct {
 #define GENHD_FL_SUPPRESS_PARTITION_INFO       32
 #define GENHD_FL_EXT_DEVT                      64 /* allow extended devt */
 #define GENHD_FL_NATIVE_CAPACITY               128
+#define GENHD_FL_BLOCK_EVENTS_ON_EXCL_WRITE    256
 
 enum {
        DISK_EVENT_MEDIA_CHANGE                 = 1 << 0, /* media changed */