From: Paolo Bonzini <pbonzini@redhat.com>

A logical volume can map to just part of underlying physical volume.
In this case, it must be treated like a partition.

(NB This patch just fixes device-mapper, not scsi.)

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
---
 block/scsi_ioctl.c     |   29 +++++++++++++++++++++++++++++
 drivers/md/dm-flakey.c |   11 ++++++++++-
 drivers/md/dm-linear.c |   12 +++++++++++-
 drivers/md/dm-mpath.c  |    6 ++++++
 include/linux/blkdev.h |    1 +
 5 files changed, 57 insertions(+), 2 deletions(-)

Index: linux/block/scsi_ioctl.c
===================================================================
--- linux.orig/block/scsi_ioctl.c
+++ linux/block/scsi_ioctl.c
@@ -690,6 +690,35 @@ int scsi_cmd_ioctl(struct request_queue 
 }
 EXPORT_SYMBOL(scsi_cmd_ioctl);
 
+int scsi_verify_blk_ioctl(struct block_device *bd, unsigned int cmd)
+{
+	if (bd && bd == bd->bd_contains)
+		return 0;
+
+	/*
+	 * Actually none of this is particularly useful on a partition
+	 * device, but let's play it safe.
+	 */
+	switch (cmd) {
+	case SCSI_IOCTL_GET_IDLUN:
+	case SCSI_IOCTL_GET_BUS_NUMBER:
+	case SCSI_IOCTL_GET_PCI:
+	case SCSI_IOCTL_PROBE_HOST:
+	case SG_GET_VERSION_NUM:
+	case SG_SET_TIMEOUT:
+	case SG_GET_TIMEOUT:
+	case SG_GET_RESERVED_SIZE:
+	case SG_SET_RESERVED_SIZE:
+	case SG_EMULATED_HOST:
+		return 0;
+	default:
+		break;
+	}
+	/* In particular, rule out all resets and host-specific ioctls.  */
+	return -ENOTTY;
+}
+EXPORT_SYMBOL(scsi_verify_blk_ioctl);
+
 static int __init blk_scsi_ioctl_init(void)
 {
 	blk_set_cmd_filter_defaults(&blk_default_cmd_filter);
Index: linux/drivers/md/dm-flakey.c
===================================================================
--- linux.orig/drivers/md/dm-flakey.c
+++ linux/drivers/md/dm-flakey.c
@@ -368,8 +368,17 @@ static int flakey_status(struct dm_targe
 static int flakey_ioctl(struct dm_target *ti, unsigned int cmd, unsigned long arg)
 {
 	struct flakey_c *fc = ti->private;
+	struct dm_dev *dev = fc->dev;
+	int r = 0;
  
-	return __blkdev_driver_ioctl(fc->dev->bdev, fc->dev->mode, cmd, arg);
+	/*
+	 * Only pass ioctls through if the device sizes match exactly.
+	 */
+	if (fc->start ||
+	    ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
+		r = scsi_verify_blk_ioctl(NULL, cmd);
+
+	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
 }
 
 static int flakey_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
Index: linux/drivers/md/dm-linear.c
===================================================================
--- linux.orig/drivers/md/dm-linear.c
+++ linux/drivers/md/dm-linear.c
@@ -116,7 +116,17 @@ static int linear_ioctl(struct dm_target
 			unsigned long arg)
 {
 	struct linear_c *lc = (struct linear_c *) ti->private;
-	return __blkdev_driver_ioctl(lc->dev->bdev, lc->dev->mode, cmd, arg);
+	struct dm_dev *dev = lc->dev;
+	int r = 0;
+
+	/*
+	 * Only pass ioctls through if the device sizes match exactly.
+	 */
+	if (lc->start ||
+	    ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
+		r = scsi_verify_blk_ioctl(NULL, cmd);
+
+	return r ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
 }
 
 static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
Index: linux/drivers/md/dm-mpath.c
===================================================================
--- linux.orig/drivers/md/dm-mpath.c
+++ linux/drivers/md/dm-mpath.c
@@ -1520,6 +1520,12 @@ static int multipath_ioctl(struct dm_tar
 
 	spin_unlock_irqrestore(&m->lock, flags);
 
+	/*
+	 * Only pass ioctls through if the device sizes match exactly.
+	 */
+	if (!r && ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT)
+		r = scsi_verify_blk_ioctl(NULL, cmd);
+
 	return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg);
 }
 
Index: linux/include/linux/blkdev.h
===================================================================
--- linux.orig/include/linux/blkdev.h
+++ linux/include/linux/blkdev.h
@@ -675,6 +675,7 @@ extern int blk_insert_cloned_request(str
 				     struct request *rq);
 extern void blk_delay_queue(struct request_queue *, unsigned long);
 extern void blk_recount_segments(struct request_queue *, struct bio *);
+extern int scsi_verify_blk_ioctl(struct block_device *, unsigned int);
 extern int scsi_cmd_ioctl(struct request_queue *, struct gendisk *, fmode_t,
 			  unsigned int, void __user *);
 extern int sg_scsi_ioctl(struct request_queue *, struct gendisk *, fmode_t,