Unverified Commit b944249b authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Christian Brauner
Browse files

fsnotify: add mount notification infrastructure 



This is just the plumbing between the event source (fs/namespace.c) and the
event consumer (fanotify).  In itself it does nothing.

Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
Link: https://lore.kernel.org/r/20250129165803.72138-2-mszeredi@redhat.com


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 2014c95a

fs/mount.h

+4 −0
Original line number Diff line number Diff line
@@ -21,6 +21,10 @@ struct mnt_namespace { 
		struct rcu_head		mnt_ns_rcu;

	};

	u64 event;

#ifdef CONFIG_FSNOTIFY

	__u32			n_fsnotify_mask;

	struct fsnotify_mark_connector __rcu *n_fsnotify_marks;

#endif

	unsigned int		nr_mounts; /* # of mounts in the namespace */

	unsigned int		pending_mounts;

	struct rb_node		mnt_ns_tree_node; /* node in the mnt_ns_tree */

fs/notify/fsnotify.c

+40 −7
Original line number Diff line number Diff line
@@ -28,6 +28,11 @@ void __fsnotify_vfsmount_delete(struct vfsmount *mnt) 
	fsnotify_clear_marks_by_mount(mnt);

}



void __fsnotify_mntns_delete(struct mnt_namespace *mntns)

{

	fsnotify_clear_marks_by_mntns(mntns);

}



/**

 * fsnotify_unmount_inodes - an sb is unmounting.  handle any watched inodes.

 * @sb: superblock being unmounted.
@@ -420,7 +425,7 @@ static int send_to_group(__u32 mask, const void *data, int data_type, 
				     file_name, cookie, iter_info);

}



static struct fsnotify_mark *fsnotify_first_mark(struct fsnotify_mark_connector **connp)

static struct fsnotify_mark *fsnotify_first_mark(struct fsnotify_mark_connector *const *connp)

{

	struct fsnotify_mark_connector *conn;

	struct hlist_node *node = NULL;
@@ -538,14 +543,15 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir, 
{

	const struct path *path = fsnotify_data_path(data, data_type);

	struct super_block *sb = fsnotify_data_sb(data, data_type);

	struct fsnotify_sb_info *sbinfo = fsnotify_sb_info(sb);

	const struct fsnotify_mnt *mnt_data = fsnotify_data_mnt(data, data_type);

	struct fsnotify_sb_info *sbinfo = sb ? fsnotify_sb_info(sb) : NULL;

	struct fsnotify_iter_info iter_info = {};

	struct mount *mnt = NULL;

	struct inode *inode2 = NULL;

	struct dentry *moved;

	int inode2_type;

	int ret = 0;

	__u32 test_mask, marks_mask;

	__u32 test_mask, marks_mask = 0;



	if (path)

		mnt = real_mount(path->mnt);
@@ -578,17 +584,20 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir, 
	if ((!sbinfo || !sbinfo->sb_marks) &&

	    (!mnt || !mnt->mnt_fsnotify_marks) &&

	    (!inode || !inode->i_fsnotify_marks) &&

	    (!inode2 || !inode2->i_fsnotify_marks))

	    (!inode2 || !inode2->i_fsnotify_marks) &&

	    (!mnt_data || !mnt_data->ns->n_fsnotify_marks))

		return 0;



	marks_mask = READ_ONCE(sb->s_fsnotify_mask);

	if (sb)

		marks_mask |= READ_ONCE(sb->s_fsnotify_mask);

	if (mnt)

		marks_mask |= READ_ONCE(mnt->mnt_fsnotify_mask);

	if (inode)

		marks_mask |= READ_ONCE(inode->i_fsnotify_mask);

	if (inode2)

		marks_mask |= READ_ONCE(inode2->i_fsnotify_mask);



	if (mnt_data)

		marks_mask |= READ_ONCE(mnt_data->ns->n_fsnotify_mask);



	/*

	 * If this is a modify event we may need to clear some ignore masks.
@@ -618,6 +627,10 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir, 
		iter_info.marks[inode2_type] =

			fsnotify_first_mark(&inode2->i_fsnotify_marks);

	}

	if (mnt_data) {

		iter_info.marks[FSNOTIFY_ITER_TYPE_MNTNS] =

			fsnotify_first_mark(&mnt_data->ns->n_fsnotify_marks);

	}



	/*

	 * We need to merge inode/vfsmount/sb mark lists so that e.g. inode mark
@@ -702,11 +715,31 @@ void file_set_fsnotify_mode(struct file *file) 
}

#endif



void fsnotify_mnt(__u32 mask, struct mnt_namespace *ns, struct vfsmount *mnt)

{

	struct fsnotify_mnt data = {

		.ns = ns,

		.mnt_id = real_mount(mnt)->mnt_id_unique,

	};



	if (WARN_ON_ONCE(!ns))

		return;



	/*

	 * This is an optimization as well as making sure fsnotify_init() has

	 * been called.

	 */

	if (!ns->n_fsnotify_marks)

		return;



	fsnotify(mask, &data, FSNOTIFY_EVENT_MNT, NULL, NULL, NULL, 0);

}



static __init int fsnotify_init(void)

{

	int ret;



	BUILD_BUG_ON(HWEIGHT32(ALL_FSNOTIFY_BITS) != 24);

	BUILD_BUG_ON(HWEIGHT32(ALL_FSNOTIFY_BITS) != 26);



	ret = init_srcu_struct(&fsnotify_mark_srcu);

	if (ret)

fs/notify/fsnotify.h

+11 −0
Original line number Diff line number Diff line
@@ -33,6 +33,12 @@ static inline struct super_block *fsnotify_conn_sb( 
	return conn->obj;

}



static inline struct mnt_namespace *fsnotify_conn_mntns(

				struct fsnotify_mark_connector *conn)

{

	return conn->obj;

}



static inline struct super_block *fsnotify_object_sb(void *obj,

			enum fsnotify_obj_type obj_type)

{
@@ -89,6 +95,11 @@ static inline void fsnotify_clear_marks_by_sb(struct super_block *sb) 
	fsnotify_destroy_marks(fsnotify_sb_marks(sb));

}



static inline void fsnotify_clear_marks_by_mntns(struct mnt_namespace *mntns)

{

	fsnotify_destroy_marks(&mntns->n_fsnotify_marks);

}



/*

 * update the dentry->d_flags of all of inode's children to indicate if inode cares

 * about events that happen to its children.

fs/notify/mark.c

+11 −3
Original line number Diff line number Diff line
@@ -107,6 +107,8 @@ static fsnotify_connp_t *fsnotify_object_connp(void *obj, 
		return &real_mount(obj)->mnt_fsnotify_marks;

	case FSNOTIFY_OBJ_TYPE_SB:

		return fsnotify_sb_marks(obj);

	case FSNOTIFY_OBJ_TYPE_MNTNS:

		return &((struct mnt_namespace *)obj)->n_fsnotify_marks;

	default:

		return NULL;

	}
@@ -120,6 +122,8 @@ static __u32 *fsnotify_conn_mask_p(struct fsnotify_mark_connector *conn) 
		return &fsnotify_conn_mount(conn)->mnt_fsnotify_mask;

	else if (conn->type == FSNOTIFY_OBJ_TYPE_SB)

		return &fsnotify_conn_sb(conn)->s_fsnotify_mask;

	else if (conn->type == FSNOTIFY_OBJ_TYPE_MNTNS)

		return &fsnotify_conn_mntns(conn)->n_fsnotify_mask;

	return NULL;

}
@@ -346,11 +350,14 @@ static void *fsnotify_detach_connector_from_object( 
		fsnotify_conn_mount(conn)->mnt_fsnotify_mask = 0;

	} else if (conn->type == FSNOTIFY_OBJ_TYPE_SB) {

		fsnotify_conn_sb(conn)->s_fsnotify_mask = 0;

	} else if (conn->type == FSNOTIFY_OBJ_TYPE_MNTNS) {

		fsnotify_conn_mntns(conn)->n_fsnotify_mask = 0;

	}



	rcu_assign_pointer(*connp, NULL);

	conn->obj = NULL;

	conn->type = FSNOTIFY_OBJ_TYPE_DETACHED;

	if (sb)

		fsnotify_update_sb_watchers(sb, conn);



	return inode;
@@ -724,7 +731,7 @@ static int fsnotify_add_mark_list(struct fsnotify_mark *mark, void *obj, 
	 * Attach the sb info before attaching a connector to any object on sb.

	 * The sb info will remain attached as long as sb lives.

	 */

	if (!fsnotify_sb_info(sb)) {

	if (sb && !fsnotify_sb_info(sb)) {

		err = fsnotify_attach_info_to_sb(sb);

		if (err)

			return err;
@@ -770,6 +777,7 @@ static int fsnotify_add_mark_list(struct fsnotify_mark *mark, void *obj, 
	/* mark should be the last entry.  last is the current last entry */

	hlist_add_behind_rcu(&mark->obj_list, &last->obj_list);

added:

	if (sb)

		fsnotify_update_sb_watchers(sb, conn);

	/*

	 * Since connector is attached to object using cmpxchg() we are

include/linux/fsnotify.h

+20 −0
Original line number Diff line number Diff line
@@ -299,6 +299,11 @@ static inline void fsnotify_vfsmount_delete(struct vfsmount *mnt) 
	__fsnotify_vfsmount_delete(mnt);

}



static inline void fsnotify_mntns_delete(struct mnt_namespace *mntns)

{

	__fsnotify_mntns_delete(mntns);

}



/*

 * fsnotify_inoderemove - an inode is going away

 */
@@ -507,4 +512,19 @@ static inline int fsnotify_sb_error(struct super_block *sb, struct inode *inode, 
			NULL, NULL, NULL, 0);

}



static inline void fsnotify_mnt_attach(struct mnt_namespace *ns, struct vfsmount *mnt)

{

	fsnotify_mnt(FS_MNT_ATTACH, ns, mnt);

}



static inline void fsnotify_mnt_detach(struct mnt_namespace *ns, struct vfsmount *mnt)

{

	fsnotify_mnt(FS_MNT_DETACH, ns, mnt);

}



static inline void fsnotify_mnt_move(struct mnt_namespace *ns, struct vfsmount *mnt)

{

	fsnotify_mnt(FS_MNT_MOVE, ns, mnt);

}



#endif	/* _LINUX_FS_NOTIFY_H */