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>
---
drivers/md/dm-flakey.c | 11 ++++++++++-
drivers/md/dm-linear.c | 12 +++++++++++-
drivers/md/dm-mpath.c | 6 ++++++
3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-flakey.c b/drivers/md/dm-flakey.c
index f84c080..9fb18c1 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 3921e3b..9728839 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 5e0090e..801d92d 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);
}

--
1.7.7.1

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2.6.27-longterm review patch. If anyone has any objections, please let us know.

------------------

commit ec8013beddd717d1740cfefb1a9b900deef85462 upstream.

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>
[bwh: Backport to 2.6.32 - drop change to drivers/md/dm-flakey.c]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/md/dm-linear.c | 12 +++++++++++-
drivers/md/dm-mpath.c | 6 ++++++
2 files changed, 17 insertions(+), 1 deletions(-)

Index: longterm-2.6.27/drivers/md/dm-linear.c
================================================== =================
--- longterm-2.6.27.orig/drivers/md/dm-linear.c 2012-02-05 22:34:32.148917626 +0100
+++ longterm-2.6.27/drivers/md/dm-linear.c 2012-02-05 22:34:47.932914720 +0100
@@ -118,12 +118,20 @@
struct block_device *bdev = lc->dev->bdev;
struct file fake_file = {};
struct dentry fake_dentry = {};
+ int r = 0;

fake_file.f_mode = lc->dev->mode;
fake_file.f_path.dentry = &fake_dentry;
fake_dentry.d_inode = bdev->bd_inode;

- return blkdev_driver_ioctl(bdev->bd_inode, &fake_file, bdev->bd_disk, cmd, arg);
+ /*
+ * Only pass ioctls through if the device sizes match exactly.
+ */
+ if (lc->start ||
+ ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT)
+ r = scsi_verify_blk_ioctl(NULL, cmd);
+
+ return r ? : blkdev_driver_ioctl(bdev->bd_inode, &fake_file, bdev->bd_disk, cmd, arg);
}

static int linear_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
Index: longterm-2.6.27/drivers/md/dm-mpath.c
================================================== =================
--- longterm-2.6.27.orig/drivers/md/dm-mpath.c 2012-02-05 22:34:32.145914857 +0100
+++ longterm-2.6.27/drivers/md/dm-mpath.c 2012-02-05 22:34:47.937916536 +0100
@@ -1421,6 +1421,12 @@

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->bd_inode, &fake_file,
bdev->bd_disk, cmd, arg);
}


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