ipc: store ipcs into IDRs

This patch introduces ipcs storage into IDRs. The main changes are:
  . This ipc_ids structure is changed: the entries array is changed into a
    root idr structure.
  . The grow_ary() routine is removed: it is not needed anymore when adding
    an ipc structure, since we are now using the IDR facility.
  . The ipc_rmid() routine interface is changed:
       . there is no need for this routine to return the pointer passed in as
         argument: it is now declared as a void
       . since the id is now part of the kern_ipc_perm structure, no need to
         have it as an argument to the routine

Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/ipc.h

@@ -89,6 +89,7 @@ struct kern_ipc_perm
 {
 	spinlock_t	lock;
 	int		deleted;
+	int		id;
 	key_t		key;
 	uid_t		uid;
 	gid_t		gid;

include/linux/msg.h

@@ -77,7 +77,6 @@ struct msg_msg {
 /* one msq_queue structure for each present queue on the system */
 struct msg_queue {
 	struct kern_ipc_perm q_perm;
-	int q_id;
 	time_t q_stime;			/* last msgsnd time */
 	time_t q_rtime;			/* last msgrcv time */
 	time_t q_ctime;			/* last change time */

include/linux/sem.h

@@ -90,7 +90,6 @@ struct sem {
 /* One sem_array data structure for each set of semaphores in the system. */
 struct sem_array {
 	struct kern_ipc_perm	sem_perm;	/* permissions .. see ipc.h */
-	int			sem_id;
 	time_t			sem_otime;	/* last semop time */
 	time_t			sem_ctime;	/* last change time */
 	struct sem		*sem_base;	/* ptr to first semaphore in array */

include/linux/shm.h

@@ -79,7 +79,6 @@ struct shmid_kernel /* private to the kernel */
 {	
 	struct kern_ipc_perm	shm_perm;
 	struct file *		shm_file;
-	int			id;
 	unsigned long		shm_nattch;
 	unsigned long		shm_segsz;
 	time_t			shm_atim;