fs: dlm: cast resource pointer to uintptr_t

This patch fixes the following warning when doing a 32 bit kernel build
when pointers are 4 byte long:

In file included from ./include/linux/byteorder/little_endian.h:5,
                 from ./arch/x86/include/uapi/asm/byteorder.h:5,
                 from ./include/asm-generic/qrwlock_types.h:6,
                 from ./arch/x86/include/asm/spinlock_types.h:7,
                 from ./include/linux/spinlock_types_raw.h:7,
                 from ./include/linux/ratelimit_types.h:7,
                 from ./include/linux/printk.h:10,
                 from ./include/asm-generic/bug.h:22,
                 from ./arch/x86/include/asm/bug.h:87,
                 from ./include/linux/bug.h:5,
                 from ./include/linux/mmdebug.h:5,
                 from ./include/linux/gfp.h:5,
                 from ./include/linux/slab.h:15,
                 from fs/dlm/dlm_internal.h:19,
                 from fs/dlm/rcom.c:12:
fs/dlm/rcom.c: In function ‘dlm_send_rcom_lock’:
./include/uapi/linux/byteorder/little_endian.h:32:43: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
 #define __cpu_to_le64(x) ((__force __le64)(__u64)(x))
                                           ^
./include/linux/byteorder/generic.h:86:21: note: in expansion of macro ‘__cpu_to_le64’
 #define cpu_to_le64 __cpu_to_le64
                     ^~~~~~~~~~~~~
fs/dlm/rcom.c:457:14: note: in expansion of macro ‘cpu_to_le64’
  rc->rc_id = cpu_to_le64(r);

The rc_id value in dlm rcom is handled as u64. The rcom implementation
uses for an unique number generation the pointer value of the used
dlm_rsb instance. However if the pointer value is 4 bytes long
-Wpointer-to-int-cast will print a warning. We get rid of that warning
to cast the pointer to uintptr_t which is either 4 or 8 bytes. There
might be a very unlikely case where this number isn't unique anymore if
using dlm in a mixed cluster of nodes and sizeof(uintptr_t) returns 4 and
8.

However this problem was already been there and this patch should get
rid of the warning.

Fixes: 2f9dbed ("dlm: use __le types for rcom messages")
Reported-by: kernel test robot <[email protected]>
Signed-off-by: Alexander Aring <[email protected]>
Signed-off-by: David Teigland <[email protected]>

fs/dlm/rcom.c

@@ -454,7 +454,7 @@ int dlm_send_rcom_lock(struct dlm_rsb *r, struct dlm_lkb *lkb)
 
 	rl = (struct rcom_lock *) rc->rc_buf;
 	pack_rcom_lock(r, lkb, rl);
-	rc->rc_id = cpu_to_le64(r);
+	rc->rc_id = cpu_to_le64((uintptr_t)r);
 
 	send_rcom(mh, rc);
  out: