fsnotify: add super block object type

Add the infrastructure to attach a mark to a super_block struct
and detach all attached marks when super block is destroyed.

This is going to be used by fanotify backend to setup super block
marks.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/notify/fdinfo.c

@@ -131,6 +131,11 @@ static void fanotify_fdinfo(struct seq_file *m, struct fsnotify_mark *mark)
 
 		seq_printf(m, "fanotify mnt_id:%x mflags:%x mask:%x ignored_mask:%x\n",
 			   mnt->mnt_id, mflags, mark->mask, mark->ignored_mask);
+	} else if (mark->connector->type == FSNOTIFY_OBJ_TYPE_SB) {
+		struct super_block *sb = fsnotify_conn_sb(mark->connector);
+
+		seq_printf(m, "fanotify sdev:%x mflags:%x mask:%x ignored_mask:%x\n",
+			   sb->s_dev, mflags, mark->mask, mark->ignored_mask);
 	}
 }
 

fs/notify/fsnotify.c

@@ -48,7 +48,7 @@ void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
  * Called during unmount with no locks held, so needs to be safe against
  * concurrent modifiers. We temporarily drop sb->s_inode_list_lock and CAN block.
  */
-void fsnotify_unmount_inodes(struct super_block *sb)
+static void fsnotify_unmount_inodes(struct super_block *sb)
 {
 	struct inode *inode, *iput_inode = NULL;
 
@@ -98,6 +98,12 @@ void fsnotify_unmount_inodes(struct super_block *sb)
 		iput(iput_inode);
 }
 
+void fsnotify_sb_delete(struct super_block *sb)
+{
+	fsnotify_unmount_inodes(sb);
+	fsnotify_clear_marks_by_sb(sb);
+}
+
 /*
  * Given an inode, first check if we care what happens to our children.  Inotify
  * and dnotify both tell their parents about events.  If we care about any event

fs/notify/fsnotify.h

@@ -21,6 +21,12 @@ static inline struct mount *fsnotify_conn_mount(
 	return container_of(conn->obj, struct mount, mnt_fsnotify_marks);
 }
 
+static inline struct super_block *fsnotify_conn_sb(
+				struct fsnotify_mark_connector *conn)
+{
+	return container_of(conn->obj, struct super_block, s_fsnotify_marks);
+}
+
 /* destroy all events sitting in this groups notification queue */
 extern void fsnotify_flush_notify(struct fsnotify_group *group);
 
@@ -43,6 +49,11 @@ static inline void fsnotify_clear_marks_by_mount(struct vfsmount *mnt)
 {
 	fsnotify_destroy_marks(&real_mount(mnt)->mnt_fsnotify_marks);
 }
+/* run the list of all marks associated with sb and destroy them */
+static inline void fsnotify_clear_marks_by_sb(struct super_block *sb)
+{
+	fsnotify_destroy_marks(&sb->s_fsnotify_marks);
+}
 /* Wait until all marks queued for destruction are destroyed */
 extern void fsnotify_wait_marks_destroyed(void);
 

fs/notify/mark.c

@@ -115,6 +115,8 @@ static __u32 *fsnotify_conn_mask_p(struct fsnotify_mark_connector *conn)
 		return &fsnotify_conn_inode(conn)->i_fsnotify_mask;
 	else if (conn->type == FSNOTIFY_OBJ_TYPE_VFSMOUNT)
 		return &fsnotify_conn_mount(conn)->mnt_fsnotify_mask;
+	else if (conn->type == FSNOTIFY_OBJ_TYPE_SB)
+		return &fsnotify_conn_sb(conn)->s_fsnotify_mask;
 	return NULL;
 }
 
@@ -192,6 +194,8 @@ static struct inode *fsnotify_detach_connector_from_object(
 		inode->i_fsnotify_mask = 0;
 	} else if (conn->type == FSNOTIFY_OBJ_TYPE_VFSMOUNT) {
 		fsnotify_conn_mount(conn)->mnt_fsnotify_mask = 0;
+	} else if (conn->type == FSNOTIFY_OBJ_TYPE_SB) {
+		fsnotify_conn_sb(conn)->s_fsnotify_mask = 0;
 	}
 
 	rcu_assign_pointer(*(conn->obj), NULL);

fs/super.c

@@ -442,7 +442,7 @@ void generic_shutdown_super(struct super_block *sb)
 		sync_filesystem(sb);
 		sb->s_flags &= ~SB_ACTIVE;
 
-		fsnotify_unmount_inodes(sb);
+		fsnotify_sb_delete(sb);
 		cgroup_writeback_umount();
 
 		evict_inodes(sb);

include/linux/fs.h

@@ -1464,6 +1464,11 @@ struct super_block {
 
 	spinlock_t		s_inode_wblist_lock;
 	struct list_head	s_inodes_wb;	/* writeback inodes */
+
+#ifdef CONFIG_FSNOTIFY
+	__u32			s_fsnotify_mask;
+	struct fsnotify_mark_connector __rcu	*s_fsnotify_marks;
+#endif
 } __randomize_layout;
 
 /* Helper functions so that in most cases filesystems will

include/linux/fsnotify_backend.h

@@ -206,12 +206,14 @@ struct fsnotify_group {
 enum fsnotify_obj_type {
 	FSNOTIFY_OBJ_TYPE_INODE,
 	FSNOTIFY_OBJ_TYPE_VFSMOUNT,
+	FSNOTIFY_OBJ_TYPE_SB,
 	FSNOTIFY_OBJ_TYPE_COUNT,
 	FSNOTIFY_OBJ_TYPE_DETACHED = FSNOTIFY_OBJ_TYPE_COUNT
 };
 
 #define FSNOTIFY_OBJ_TYPE_INODE_FL	(1U << FSNOTIFY_OBJ_TYPE_INODE)
 #define FSNOTIFY_OBJ_TYPE_VFSMOUNT_FL	(1U << FSNOTIFY_OBJ_TYPE_VFSMOUNT)
+#define FSNOTIFY_OBJ_TYPE_SB_FL		(1U << FSNOTIFY_OBJ_TYPE_SB)
 #define FSNOTIFY_OBJ_ALL_TYPES_MASK	((1U << FSNOTIFY_OBJ_TYPE_COUNT) - 1)
 
 static inline bool fsnotify_valid_obj_type(unsigned int type)
@@ -255,6 +257,7 @@ static inline struct fsnotify_mark *fsnotify_iter_##name##_mark( \
 
 FSNOTIFY_ITER_FUNCS(inode, INODE)
 FSNOTIFY_ITER_FUNCS(vfsmount, VFSMOUNT)
+FSNOTIFY_ITER_FUNCS(sb, SB)
 
 #define fsnotify_foreach_obj_type(type) \
 	for (type = 0; type < FSNOTIFY_OBJ_TYPE_COUNT; type++)
@@ -267,8 +270,8 @@ struct fsnotify_mark_connector;
 typedef struct fsnotify_mark_connector __rcu *fsnotify_connp_t;
 
 /*
- * Inode / vfsmount point to this structure which tracks all marks attached to
- * the inode / vfsmount. The reference to inode / vfsmount is held by this
+ * Inode/vfsmount/sb point to this structure which tracks all marks attached to
+ * the inode/vfsmount/sb. The reference to inode/vfsmount/sb is held by this
  * structure. We destroy this structure when there are no more marks attached
  * to it. The structure is protected by fsnotify_mark_srcu.
  */
@@ -335,6 +338,7 @@ extern int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int dat
 extern int __fsnotify_parent(const struct path *path, struct dentry *dentry, __u32 mask);
 extern void __fsnotify_inode_delete(struct inode *inode);
 extern void __fsnotify_vfsmount_delete(struct vfsmount *mnt);
+extern void fsnotify_sb_delete(struct super_block *sb);
 extern u32 fsnotify_get_cookie(void);
 
 static inline int fsnotify_inode_watches_children(struct inode *inode)
@@ -455,9 +459,13 @@ static inline void fsnotify_clear_inode_marks_by_group(struct fsnotify_group *gr
 {
 	fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_INODE_FL);
 }
+/* run all the marks in a group, and clear all of the sn marks */
+static inline void fsnotify_clear_sb_marks_by_group(struct fsnotify_group *group)
+{
+	fsnotify_clear_marks_by_group(group, FSNOTIFY_OBJ_TYPE_SB_FL);
+}
 extern void fsnotify_get_mark(struct fsnotify_mark *mark);
 extern void fsnotify_put_mark(struct fsnotify_mark *mark);
-extern void fsnotify_unmount_inodes(struct super_block *sb);
 extern void fsnotify_finish_user_wait(struct fsnotify_iter_info *iter_info);
 extern bool fsnotify_prepare_user_wait(struct fsnotify_iter_info *iter_info);
 
@@ -484,6 +492,9 @@ static inline void __fsnotify_inode_delete(struct inode *inode)
 static inline void __fsnotify_vfsmount_delete(struct vfsmount *mnt)
 {}
 
+static inline void fsnotify_sb_delete(struct super_block *sb)
+{}
+
 static inline void fsnotify_update_flags(struct dentry *dentry)
 {}