fsnotify: Remove indirection from fsnotify_detach_mark()

fsnotify_detach_mark() calls fsnotify_destroy_inode_mark() or
fsnotify_destroy_vfsmount_mark() to remove mark from object list. These
two functions are however very similar and differ only in the lock they
use to protect the object list of marks. Simplify the code by removing
the indirection and removing mark from the object list in a common
function.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/notify/fsnotify.h

@@ -18,10 +18,6 @@ extern struct srcu_struct fsnotify_mark_srcu;
 extern int fsnotify_compare_groups(struct fsnotify_group *a,
 				   struct fsnotify_group *b);
 
-/* vfsmount specific destruction of a mark */
-extern void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark);
-/* inode specific destruction of a mark */
-extern struct inode *fsnotify_destroy_inode_mark(struct fsnotify_mark *mark);
 /* Find mark belonging to given group in the list of marks */
 extern struct fsnotify_mark *fsnotify_find_mark(
 					struct fsnotify_mark_connector *conn,

fs/notify/inode_mark.c

@@ -35,27 +35,6 @@ void fsnotify_recalc_inode_mask(struct inode *inode)
 	fsnotify_recalc_mask(inode->i_fsnotify_marks);
 }
 
-struct inode *fsnotify_destroy_inode_mark(struct fsnotify_mark *mark)
-{
-	struct inode *inode = mark->connector->inode;
-	bool empty;
-
-	BUG_ON(!mutex_is_locked(&mark->group->mark_mutex));
-	assert_spin_locked(&mark->lock);
-
-	spin_lock(&inode->i_lock);
-
-	hlist_del_init_rcu(&mark->obj_list);
-	empty = hlist_empty(&mark->connector->list);
-	mark->connector = NULL;
-
-	spin_unlock(&inode->i_lock);
-
-	fsnotify_recalc_mask(inode->i_fsnotify_marks);
-
-	return empty ? inode : NULL;
-}
-
 /*
  * Given a group clear all of the inode marks associated with that group.
  */

fs/notify/mark.c

@@ -141,6 +141,30 @@ void fsnotify_recalc_mask(struct fsnotify_mark_connector *conn)
 	}
 }
 
+static struct inode *fsnotify_detach_from_object(struct fsnotify_mark *mark)
+{
+	struct fsnotify_mark_connector *conn;
+	struct inode *inode = NULL;
+	spinlock_t *lock;
+
+	conn = mark->connector;
+	if (conn->flags & FSNOTIFY_OBJ_TYPE_INODE)
+		lock = &conn->inode->i_lock;
+	else
+		lock = &conn->mnt->mnt_root->d_lock;
+	spin_lock(lock);
+	hlist_del_init_rcu(&mark->obj_list);
+	if (hlist_empty(&conn->list)) {
+		if (conn->flags & FSNOTIFY_OBJ_TYPE_INODE)
+			inode = conn->inode;
+	}
+	mark->connector = NULL;
+	spin_unlock(lock);
+	fsnotify_recalc_mask(conn);
+
+	return inode;
+}
+
 /*
  * Remove mark from inode / vfsmount list, group list, drop inode reference
  * if we got one.
@@ -164,12 +188,8 @@ void fsnotify_detach_mark(struct fsnotify_mark *mark)
 
 	mark->flags &= ~FSNOTIFY_MARK_FLAG_ATTACHED;
 
-	if (mark->connector->flags & FSNOTIFY_OBJ_TYPE_INODE)
-		inode = fsnotify_destroy_inode_mark(mark);
-	else if (mark->connector->flags & FSNOTIFY_OBJ_TYPE_VFSMOUNT)
-		fsnotify_destroy_vfsmount_mark(mark);
-	else
-		BUG();
+	inode = fsnotify_detach_from_object(mark);
+
 	/*
 	 * Note that we didn't update flags telling whether inode cares about
 	 * what's happening with children. We update these flags from

fs/notify/vfsmount_mark.c

@@ -39,24 +39,6 @@ void fsnotify_recalc_vfsmount_mask(struct vfsmount *mnt)
 	fsnotify_recalc_mask(real_mount(mnt)->mnt_fsnotify_marks);
 }
 
-void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark)
-{
-	struct vfsmount *mnt = mark->connector->mnt;
-	struct mount *m = real_mount(mnt);
-
-	BUG_ON(!mutex_is_locked(&mark->group->mark_mutex));
-	assert_spin_locked(&mark->lock);
-
-	spin_lock(&mnt->mnt_root->d_lock);
-
-	hlist_del_init_rcu(&mark->obj_list);
-	mark->connector = NULL;
-
-	spin_unlock(&mnt->mnt_root->d_lock);
-
-	fsnotify_recalc_mask(m->mnt_fsnotify_marks);
-}
-
 /*
  * given a group and vfsmount, find the mark associated with that combination.
  * if found take a reference to that mark and return it, else return NULL