dm: do not forward ioctls from logical volumes to the underlying device

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

Based on a patch from Alasdair G Kergon.

Cc: Alasdair G Kergon <agk@redhat.com>
Cc: dm-devel@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 27 insertions, 2 deletions

diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
index f84c08029b21..9fb18c147825 100644
--- a/drivers/md/dm-flakey.c
+++ b/drivers/md/dm-flakey.c
@@ -368,8 +368,17 @@ static int flakey_status(struct dm_target *ti, status_type_t type,
 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,
diff --git a/drivers/md/dm-linear.c b/drivers/md/dm-linear.c
index 3921e3bb43c1..9728839f844a 100644
--- a/drivers/md/dm-linear.c
+++ b/drivers/md/dm-linear.c
@@ -116,7 +116,17 @@ static int linear_ioctl(struct dm_target *ti, unsigned int cmd,
                         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,
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 5e0090ef4182..801d92d237cf 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1520,6 +1520,12 @@ static int multipath_ioctl(struct dm_target *ti, unsigned int cmd,
 
         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);
 }