dm target: remove struct tt_internal

The tt_internal is really just a list_head to manage registered target_type
in a double linked list,

Here embed the list_head into target_type directly,
1. to avoid kmalloc/kfree;
2. then tt_internal is really unneeded;

Cc: stable@kernel.org
Signed-off-by: Cheng Renquan <crquan@gmail.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Reviewed-by: Alasdair G Kergon <agk@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 8209e08969f9..66ec05a57955 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -139,6 +139,9 @@ struct target_type {
         dm_ioctl_fn ioctl;
         dm_merge_fn merge;
         dm_busy_fn busy;
+
+        /* For internal device-mapper use. */
+        struct list_head list;
 };
 
 struct io_restrictions {