fsnotify: Move object pointer to fsnotify_mark_connector

Move pointer to inode / vfsmount from mark itself to the
fsnotify_mark_connector structure. This is another step on the path
towards decoupling inode / vfsmount lifetime from notification mark
lifetime.

Reviewed-by: Miklos Szeredi <[e-mail]>
Reviewed-by: Amir Goldstein <[e-mail]>
Signed-off-by: Jan Kara <[e-mail]>

fs/notify/dnotify/dnotify.c

···
 	if (old_mask == new_mask)
 		return;
 
-	if (fsn_mark->inode)
-		fsnotify_recalc_inode_mask(fsn_mark->inode);
+	if (fsn_mark->connector)
+		fsnotify_recalc_inode_mask(fsn_mark->connector->inode);
 }
 
 /*

fs/notify/fdinfo.c

···
 	struct inotify_inode_mark *inode_mark;
 	struct inode *inode;
 
-	if (!(mark->flags & FSNOTIFY_MARK_FLAG_INODE))
+	if (!(mark->connector->flags & FSNOTIFY_OBJ_TYPE_INODE))
 		return;
 
 	inode_mark = container_of(mark, struct inotify_inode_mark, fsn_mark);
-	inode = igrab(mark->inode);
+	inode = igrab(mark->connector->inode);
 	if (inode) {
 		/*
 		 * IN_ALL_EVENTS represents all of the mask bits
···
 	if (mark->flags & FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY)
 		mflags |= FAN_MARK_IGNORED_SURV_MODIFY;
 
-	if (mark->flags & FSNOTIFY_MARK_FLAG_INODE) {
-		inode = igrab(mark->inode);
+	if (mark->connector->flags & FSNOTIFY_OBJ_TYPE_INODE) {
+		inode = igrab(mark->connector->inode);
 		if (!inode)
 			return;
 		seq_printf(m, "fanotify ino:%lx sdev:%x mflags:%x mask:%x ignored_mask:%x ",
···
 		show_mark_fhandle(m, inode);
 		seq_putc(m, '\n');
 		iput(inode);
-	} else if (mark->flags & FSNOTIFY_MARK_FLAG_VFSMOUNT) {
-		struct mount *mnt = real_mount(mark->mnt);
+	} else if (mark->connector->flags & FSNOTIFY_OBJ_TYPE_VFSMOUNT) {
+		struct mount *mnt = real_mount(mark->connector->mnt);
 
 		seq_printf(m, "fanotify mnt_id:%x mflags:%x mask:%x ignored_mask:%x\n",
 			   mnt->mnt_id, mflags, mark->mask, mark->ignored_mask);

fs/notify/fsnotify.h

···
 /* Add mark to a proper place in mark list */
 extern int fsnotify_add_mark_list(struct fsnotify_mark_connector **connp,
 				  struct fsnotify_mark *mark,
+				  struct inode *inode, struct vfsmount *mnt,
 				  int allow_dups);
 /* add a mark to an inode */
 extern int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
···
 extern struct fsnotify_mark *fsnotify_find_mark(
 					struct fsnotify_mark_connector *conn,
 					struct fsnotify_group *group);
-/* Destroy all marks in the given list protected by 'lock' */
+/* Destroy all marks connected via given connector protected by 'lock' */
 extern void fsnotify_destroy_marks(struct fsnotify_mark_connector *conn,
 				   spinlock_t *lock);
 /* run the list of all marks associated with inode and destroy them */

fs/notify/inode_mark.c

···
 
 void fsnotify_destroy_inode_mark(struct fsnotify_mark *mark)
 {
-	struct inode *inode = mark->inode;
+	struct inode *inode = mark->connector->inode;
 
 	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);
-	mark->inode = NULL;
+	mark->connector = NULL;
 
 	/*
 	 * this mark is now off the inode->i_fsnotify_marks list and we
···
  */
 void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group)
 {
-	fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_INODE);
+	fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_OBJ_TYPE_INODE);
 }
 
 /*
···
 
 	assert_spin_locked(&mark->lock);
 
-	if (mask &&
-	    mark->inode &&
+	if (mask && mark->connector &&
 	    !(mark->flags & FSNOTIFY_MARK_FLAG_OBJECT_PINNED)) {
 		mark->flags |= FSNOTIFY_MARK_FLAG_OBJECT_PINNED;
-		inode = igrab(mark->inode);
+		inode = igrab(mark->connector->inode);
 		/*
 		 * we shouldn't be able to get here if the inode wasn't
 		 * already safely held in memory.  But bug in case it
···
 {
 	int ret;
 
-	mark->flags |= FSNOTIFY_MARK_FLAG_INODE;
-
 	BUG_ON(!mutex_is_locked(&group->mark_mutex));
 	assert_spin_locked(&mark->lock);
 
 	spin_lock(&inode->i_lock);
-	mark->inode = inode;
-	ret = fsnotify_add_mark_list(&inode->i_fsnotify_marks, mark,
-				     allow_dups);
+	ret = fsnotify_add_mark_list(&inode->i_fsnotify_marks, mark, inode,
+				     NULL, allow_dups);
 	inode->i_fsnotify_mask = fsnotify_recalc_mask(inode->i_fsnotify_marks);
 	spin_unlock(&inode->i_lock);
 

fs/notify/mark.c

···
 
 	mark->flags &= ~FSNOTIFY_MARK_FLAG_ATTACHED;
 
-	if (mark->flags & FSNOTIFY_MARK_FLAG_INODE) {
-		inode = mark->inode;
+	if (mark->connector->flags & FSNOTIFY_OBJ_TYPE_INODE) {
+		inode = mark->connector->inode;
 		fsnotify_destroy_inode_mark(mark);
-	} else if (mark->flags & FSNOTIFY_MARK_FLAG_VFSMOUNT)
+	} else if (mark->connector->flags & FSNOTIFY_OBJ_TYPE_VFSMOUNT)
 		fsnotify_destroy_vfsmount_mark(mark);
 	else
 		BUG();
···
 
 	mark->mask = mask;
 
-	if (mark->flags & FSNOTIFY_MARK_FLAG_INODE)
+	if (mark->connector && mark->connector->flags & FSNOTIFY_OBJ_TYPE_INODE)
 		fsnotify_set_inode_mark_mask_locked(mark, mask);
 }
 
···
 }
 
 static int fsnotify_attach_connector_to_object(
-					struct fsnotify_mark_connector **connp)
+					struct fsnotify_mark_connector **connp,
+					struct inode *inode,
+					struct vfsmount *mnt)
 {
 	struct fsnotify_mark_connector *conn;
 
···
 	if (!conn)
 		return -ENOMEM;
 	INIT_HLIST_HEAD(&conn->list);
+	if (inode) {
+		conn->flags = FSNOTIFY_OBJ_TYPE_INODE;
+		conn->inode = inode;
+	} else {
+		conn->flags = FSNOTIFY_OBJ_TYPE_VFSMOUNT;
+		conn->mnt = mnt;
+	}
 	/*
 	 * Make sure 'conn' initialization is visible. Matches
 	 * lockless_dereference() in fsnotify().
···
  * priority, highest number first, and then by the group's location in memory.
  */
 int fsnotify_add_mark_list(struct fsnotify_mark_connector **connp,
-			   struct fsnotify_mark *mark, int allow_dups)
+			   struct fsnotify_mark *mark, struct inode *inode,
+			   struct vfsmount *mnt, int allow_dups)
 {
 	struct fsnotify_mark *lmark, *last = NULL;
 	struct fsnotify_mark_connector *conn;
···
 	int err;
 
 	if (!*connp) {
-		err = fsnotify_attach_connector_to_object(connp);
+		err = fsnotify_attach_connector_to_object(connp, inode, mnt);
 		if (err)
 			return err;
 	}
···
 	/* is mark the first mark? */
 	if (hlist_empty(&conn->list)) {
 		hlist_add_head_rcu(&mark->obj_list, &conn->list);
-		return 0;
+		goto added;
 	}
 
 	/* should mark be in the middle of the current list? */
···
 		cmp = fsnotify_compare_groups(lmark->group, mark->group);
 		if (cmp >= 0) {
 			hlist_add_before_rcu(&mark->obj_list, &lmark->obj_list);
-			return 0;
+			goto added;
 		}
 	}
 
 	BUG_ON(last == NULL);
 	/* mark should be the last entry.  last is the current last entry */
 	hlist_add_behind_rcu(&mark->obj_list, &last->obj_list);
+added:
+	mark->connector = conn;
 	return 0;
 }
 
···
 	 */
 	mutex_lock_nested(&group->mark_mutex, SINGLE_DEPTH_NESTING);
 	list_for_each_entry_safe(mark, lmark, &group->marks_list, g_list) {
-		if (mark->flags & flags)
+		if (mark->connector->flags & flags)
 			list_move(&mark->g_list, &to_free);
 	}
 	mutex_unlock(&group->mark_mutex);

fs/notify/vfsmount_mark.c

···
 
 void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group)
 {
-	fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_MARK_FLAG_VFSMOUNT);
+	fsnotify_clear_marks_by_group_flags(group, FSNOTIFY_OBJ_TYPE_VFSMOUNT);
 }
 
 /*
···
 
 void fsnotify_destroy_vfsmount_mark(struct fsnotify_mark *mark)
 {
-	struct vfsmount *mnt = mark->mnt;
+	struct vfsmount *mnt = mark->connector->mnt;
 	struct mount *m = real_mount(mnt);
 
 	BUG_ON(!mutex_is_locked(&mark->group->mark_mutex));
···
 	spin_lock(&mnt->mnt_root->d_lock);
 
 	hlist_del_init_rcu(&mark->obj_list);
-	mark->mnt = NULL;
+	mark->connector = NULL;
 
 	m->mnt_fsnotify_mask = fsnotify_recalc_mask(m->mnt_fsnotify_marks);
 	spin_unlock(&mnt->mnt_root->d_lock);
···
 	struct mount *m = real_mount(mnt);
 	int ret;
 
-	mark->flags |= FSNOTIFY_MARK_FLAG_VFSMOUNT;
-
 	BUG_ON(!mutex_is_locked(&group->mark_mutex));
 	assert_spin_locked(&mark->lock);
 
 	spin_lock(&mnt->mnt_root->d_lock);
-	mark->mnt = mnt;
-	ret = fsnotify_add_mark_list(&m->mnt_fsnotify_marks, mark, allow_dups);
+	ret = fsnotify_add_mark_list(&m->mnt_fsnotify_marks, mark, NULL, mnt,
+				     allow_dups);
 	m->mnt_fsnotify_mask = fsnotify_recalc_mask(m->mnt_fsnotify_marks);
 	spin_unlock(&mnt->mnt_root->d_lock);
 

include/linux/fsnotify_backend.h

···
  * freed.
  */
 struct fsnotify_mark_connector {
+#define FSNOTIFY_OBJ_TYPE_INODE		0x01
+#define FSNOTIFY_OBJ_TYPE_VFSMOUNT	0x02
+	unsigned int flags;	/* Type of object [lock] */
+	union {	/* Object pointer [lock] */
+		struct inode *inode;
+		struct vfsmount *mnt;
+	};
 	struct hlist_head list;
 };
 
···
 	spinlock_t lock;
 	/* List of marks for inode / vfsmount [obj_lock] */
 	struct hlist_node obj_list;
-	union {	/* Object pointer [mark->lock, group->mark_mutex] */
-		struct inode *inode;	/* inode this mark is associated with */
-		struct vfsmount *mnt;	/* vfsmount this mark is associated with */
-	};
+	/* Head of list of marks for an object [mark->lock, group->mark_mutex] */
+	struct fsnotify_mark_connector *connector;
 	/* Events types to ignore [mark->lock, group->mark_mutex] */
 	__u32 ignored_mask;
-#define FSNOTIFY_MARK_FLAG_INODE		0x01
-#define FSNOTIFY_MARK_FLAG_VFSMOUNT		0x02
 #define FSNOTIFY_MARK_FLAG_OBJECT_PINNED	0x04
 #define FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY	0x08
 #define FSNOTIFY_MARK_FLAG_ALIVE		0x10
···
 extern void fsnotify_clear_vfsmount_marks_by_group(struct fsnotify_group *group);
 /* run all the marks in a group, and clear all of the inode marks */
 extern void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *group);
-/* run all the marks in a group, and clear all of the marks where mark->flags & flags is true*/
+/* run all the marks in a group, and clear all of the marks attached to given object type */
 extern void fsnotify_clear_marks_by_group_flags(struct fsnotify_group *group, unsigned int flags);
 extern void fsnotify_connector_free(struct fsnotify_mark_connector **connp);
 extern void fsnotify_get_mark(struct fsnotify_mark *mark);

kernel/audit_tree.c

···
 /*
  * Function to return search key in our hash from chunk. Key 0 is special and
  * should never be present in the hash.
+ *
+ * Must be called with chunk->mark.lock held to protect from connector
+ * becoming NULL.
  */
+static unsigned long __chunk_to_key(struct audit_chunk *chunk)
+{
+	if (!chunk->mark.connector)
+		return 0;
+	return (unsigned long)chunk->mark.connector->inode;
+}
+
 static unsigned long chunk_to_key(struct audit_chunk *chunk)
 {
-	return (unsigned long)chunk->mark.inode;
+	unsigned long key;
+
+	spin_lock(&chunk->mark.lock);
+	key = __chunk_to_key(chunk);
+	spin_unlock(&chunk->mark.lock);
+	return key;
 }
 
 static inline struct list_head *chunk_hash(unsigned long key)
···
 /* hash_lock & entry->lock is held by caller */
 static void insert_hash(struct audit_chunk *chunk)
 {
-	unsigned long key = chunk_to_key(chunk);
+	unsigned long key = __chunk_to_key(chunk);
 	struct list_head *list;
 
 	if (!(chunk->mark.flags & FSNOTIFY_MARK_FLAG_ATTACHED))
···
 	if (!new)
 		goto Fallback;
 
-	if (fsnotify_add_mark_locked(&new->mark, entry->group, entry->inode,
-				     NULL, 1)) {
+	if (fsnotify_add_mark_locked(&new->mark, entry->group,
+				     entry->connector->inode, NULL, 1)) {
 		fsnotify_put_mark(&new->mark);
 		goto Fallback;
 	}
···
 	}
 
 	if (fsnotify_add_mark_locked(chunk_entry, old_entry->group,
-				     old_entry->inode, NULL, 1)) {
+			     old_entry->connector->inode, NULL, 1)) {
 		spin_unlock(&old_entry->lock);
 		mutex_unlock(&old_entry->group->mark_mutex);
 		fsnotify_put_mark(chunk_entry);