[PATCH] dm: support ioctls on mapped devices

Extend the core device-mapper infrastructure to accept arbitrary ioctls on a
mapped device provided that it has exactly one target and it is capable of
supporting ioctls.

[We can't use unlocked_ioctl because we need 'inode': 'file' might be NULL.
Is it worth changing this?]

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

Arnd Bergmann <arnd@arndb.de> wrote:

> Am Wednesday 21 June 2006 21:31 schrieb Alasdair G Kergon:
> > static struct block_device_operations dm_blk_dops = {
> > .open = dm_blk_open,
> > .release = dm_blk_close,
> > +.ioctl = dm_blk_ioctl,
> > .getgeo = dm_blk_getgeo,
> > .owner = THIS_MODULE
>
> I guess this also needs a ->compat_ioctl method, otherwise it won't
> work for ioctl numbers that have a compat_ioctl implementation in the
> low-level device driver.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index e3d1c33d1558..d44a99650af3 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -64,6 +64,10 @@ typedef int (*dm_status_fn) (struct dm_target *ti, status_type_t status_type,
 
 typedef int (*dm_message_fn) (struct dm_target *ti, unsigned argc, char **argv);
 
+typedef int (*dm_ioctl_fn) (struct dm_target *ti, struct inode *inode,
+                            struct file *filp, unsigned int cmd,
+                            unsigned long arg);
+
 void dm_error(const char *message);
 
 /*
@@ -91,6 +95,7 @@ struct target_type {
         dm_resume_fn resume;
         dm_status_fn status;
         dm_message_fn message;
+        dm_ioctl_fn ioctl;
 };
 
 struct io_restrictions {