inotify: convert inotify_add_to_idr() to use idr_alloc_cyclic()

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: John McCutchan <john@johnmccutchan.com>
Cc: Robert Love <rlove@rlove.org>
Cc: Eric Paris <eparis@parisplace.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/notify/inotify/inotify_user.c

@@ -359,19 +359,17 @@ static int inotify_find_inode(const char __user *dirname, struct path *path, uns
 }
 
 static int inotify_add_to_idr(struct idr *idr, spinlock_t *idr_lock,
-			      int *last_wd,
 			      struct inotify_inode_mark *i_mark)
 {
 	int ret;
 
 	idr_preload(GFP_KERNEL);
 	spin_lock(idr_lock);
 
-	ret = idr_alloc(idr, i_mark, *last_wd + 1, 0, GFP_NOWAIT);
+	ret = idr_alloc_cyclic(idr, i_mark, 1, 0, GFP_NOWAIT);
 	if (ret >= 0) {
 		/* we added the mark to the idr, take a reference */
 		i_mark->wd = ret;
-		*last_wd = i_mark->wd;
 		fsnotify_get_mark(&i_mark->fsn_mark);
 	}
 
@@ -638,8 +636,7 @@ static int inotify_new_watch(struct fsnotify_group *group,
 	if (atomic_read(&group->inotify_data.user->inotify_watches) >= inotify_max_user_watches)
 		goto out_err;
 
-	ret = inotify_add_to_idr(idr, idr_lock, &group->inotify_data.last_wd,
-				 tmp_i_mark);
+	ret = inotify_add_to_idr(idr, idr_lock, tmp_i_mark);
 	if (ret)
 		goto out_err;
 
@@ -697,7 +694,6 @@ static struct fsnotify_group *inotify_new_group(unsigned int max_events)
 
 	spin_lock_init(&group->inotify_data.idr_lock);
 	idr_init(&group->inotify_data.idr);
-	group->inotify_data.last_wd = 0;
 	group->inotify_data.user = get_current_user();
 
 	if (atomic_inc_return(&group->inotify_data.user->inotify_devs) >

include/linux/fsnotify_backend.h

@@ -157,7 +157,6 @@ struct fsnotify_group {
 		struct inotify_group_private_data {
 			spinlock_t	idr_lock;
 			struct idr      idr;
-			u32             last_wd;
 			struct user_struct      *user;
 		} inotify_data;
 #endif