Merge tag 'fsnotify_for_v5.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

Pull fsnotify fixes from Jan Kara:
 "Fixes for userspace breakage caused by fsnotify changes ~3 years ago
  and one fanotify cleanup"

* tag 'fsnotify_for_v5.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  fsnotify: fix fsnotify hooks in pseudo filesystems
  fsnotify: invalidate dcache before IN_DELETE event
  fanotify: remove variable set but not used

Author: torvalds

fs/btrfs/ioctl.c

@@ -3152,10 +3152,8 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
 	btrfs_inode_lock(inode, 0);
 	err = btrfs_delete_subvolume(dir, dentry);
 	btrfs_inode_unlock(inode, 0);
-	if (!err) {
-		fsnotify_rmdir(dir, dentry);
-		d_delete(dentry);
-	}
+	if (!err)
+		d_delete_notify(dir, dentry);
 
 out_dput:
 	dput(dentry);

fs/configfs/dir.c

@@ -1780,8 +1780,8 @@ void configfs_unregister_group(struct config_group *group)
 	configfs_detach_group(&group->cg_item);
 	d_inode(dentry)->i_flags |= S_DEAD;
 	dont_mount(dentry);
+	d_drop(dentry);
 	fsnotify_rmdir(d_inode(parent), dentry);
-	d_delete(dentry);
 	inode_unlock(d_inode(parent));
 
 	dput(dentry);
@@ -1922,10 +1922,10 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
 	configfs_detach_group(&group->cg_item);
 	d_inode(dentry)->i_flags |= S_DEAD;
 	dont_mount(dentry);
-	fsnotify_rmdir(d_inode(root), dentry);
 	inode_unlock(d_inode(dentry));
 
-	d_delete(dentry);
+	d_drop(dentry);
+	fsnotify_rmdir(d_inode(root), dentry);
 
 	inode_unlock(d_inode(root));
 

fs/devpts/inode.c

@@ -621,8 +621,8 @@ void devpts_pty_kill(struct dentry *dentry)
 
 	dentry->d_fsdata = NULL;
 	drop_nlink(dentry->d_inode);
-	fsnotify_unlink(d_inode(dentry->d_parent), dentry);
 	d_drop(dentry);
+	fsnotify_unlink(d_inode(dentry->d_parent), dentry);
 	dput(dentry);	/* d_alloc_name() in devpts_pty_new() */
 }
 

fs/namei.c

@@ -4024,13 +4024,12 @@ int vfs_rmdir(struct user_namespace *mnt_userns, struct inode *dir,
 	dentry->d_inode->i_flags |= S_DEAD;
 	dont_mount(dentry);
 	detach_mounts(dentry);
-	fsnotify_rmdir(dir, dentry);
 
 out:
 	inode_unlock(dentry->d_inode);
 	dput(dentry);
 	if (!error)
-		d_delete(dentry);
+		d_delete_notify(dir, dentry);
 	return error;
 }
 EXPORT_SYMBOL(vfs_rmdir);
@@ -4152,17 +4151,18 @@ int vfs_unlink(struct user_namespace *mnt_userns, struct inode *dir,
 			if (!error) {
 				dont_mount(dentry);
 				detach_mounts(dentry);
-				fsnotify_unlink(dir, dentry);
 			}
 		}
 	}
 out:
 	inode_unlock(target);
 
 	/* We don't d_delete() NFS sillyrenamed files--they still exist. */
-	if (!error && !(dentry->d_flags & DCACHE_NFSFS_RENAMED)) {
+	if (!error && dentry->d_flags & DCACHE_NFSFS_RENAMED) {
+		fsnotify_unlink(dir, dentry);
+	} else if (!error) {
 		fsnotify_link_count(target);
-		d_delete(dentry);
+		d_delete_notify(dir, dentry);
 	}
 
 	return error;

fs/nfsd/nfsctl.c

@@ -1247,7 +1247,8 @@ static void nfsdfs_remove_file(struct inode *dir, struct dentry *dentry)
 	clear_ncl(d_inode(dentry));
 	dget(dentry);
 	ret = simple_unlink(dir, dentry);
-	d_delete(dentry);
+	d_drop(dentry);
+	fsnotify_unlink(dir, dentry);
 	dput(dentry);
 	WARN_ON_ONCE(ret);
 }
@@ -1338,8 +1339,8 @@ void nfsd_client_rmdir(struct dentry *dentry)
 	dget(dentry);
 	ret = simple_rmdir(dir, dentry);
 	WARN_ON_ONCE(ret);
+	d_drop(dentry);
 	fsnotify_rmdir(dir, dentry);
-	d_delete(dentry);
 	dput(dentry);
 	inode_unlock(dir);
 }

fs/notify/fanotify/fanotify_user.c

@@ -158,7 +158,6 @@ static size_t fanotify_event_len(unsigned int info_mode,
 				 struct fanotify_event *event)
 {
 	size_t event_len = FAN_EVENT_METADATA_LEN;
-	struct fanotify_info *info;
 	int fh_len;
 	int dot_len = 0;
 
@@ -168,8 +167,6 @@ static size_t fanotify_event_len(unsigned int info_mode,
 	if (fanotify_is_error_event(event->mask))
 		event_len += FANOTIFY_ERROR_INFO_LEN;
 
-	info = fanotify_event_info(event);
-
 	if (fanotify_event_has_any_dir_fh(event)) {
 		event_len += fanotify_dir_name_info_len(event);
 	} else if ((info_mode & FAN_REPORT_NAME) &&

include/linux/fsnotify.h

@@ -224,17 +224,54 @@ static inline void fsnotify_link(struct inode *dir, struct inode *inode,
 		      dir, &new_dentry->d_name, 0);
 }
 
+/*
+ * fsnotify_delete - @dentry was unlinked and unhashed
+ *
+ * Caller must make sure that dentry->d_name is stable.
+ *
+ * Note: unlike fsnotify_unlink(), we have to pass also the unlinked inode
+ * as this may be called after d_delete() and old_dentry may be negative.
+ */
+static inline void fsnotify_delete(struct inode *dir, struct inode *inode,
+				   struct dentry *dentry)
+{
+	__u32 mask = FS_DELETE;
+
+	if (S_ISDIR(inode->i_mode))
+		mask |= FS_ISDIR;
+
+	fsnotify_name(mask, inode, FSNOTIFY_EVENT_INODE, dir, &dentry->d_name,
+		      0);
+}
+
+/**
+ * d_delete_notify - delete a dentry and call fsnotify_delete()
+ * @dentry: The dentry to delete
+ *
+ * This helper is used to guaranty that the unlinked inode cannot be found
+ * by lookup of this name after fsnotify_delete() event has been delivered.
+ */
+static inline void d_delete_notify(struct inode *dir, struct dentry *dentry)
+{
+	struct inode *inode = d_inode(dentry);
+
+	ihold(inode);
+	d_delete(dentry);
+	fsnotify_delete(dir, inode, dentry);
+	iput(inode);
+}
+
 /*
  * fsnotify_unlink - 'name' was unlinked
  *
  * Caller must make sure that dentry->d_name is stable.
  */
 static inline void fsnotify_unlink(struct inode *dir, struct dentry *dentry)
 {
-	/* Expected to be called before d_delete() */
-	WARN_ON_ONCE(d_is_negative(dentry));
+	if (WARN_ON_ONCE(d_is_negative(dentry)))
+		return;
 
-	fsnotify_dirent(dir, dentry, FS_DELETE);
+	fsnotify_delete(dir, d_inode(dentry), dentry);
 }
 
 /*
@@ -258,10 +295,10 @@ static inline void fsnotify_mkdir(struct inode *dir, struct dentry *dentry)
  */
 static inline void fsnotify_rmdir(struct inode *dir, struct dentry *dentry)
 {
-	/* Expected to be called before d_delete() */
-	WARN_ON_ONCE(d_is_negative(dentry));
+	if (WARN_ON_ONCE(d_is_negative(dentry)))
+		return;
 
-	fsnotify_dirent(dir, dentry, FS_DELETE | FS_ISDIR);
+	fsnotify_delete(dir, d_inode(dentry), dentry);
 }
 
 /*

net/sunrpc/rpc_pipe.c

@@ -600,9 +600,9 @@ static int __rpc_rmdir(struct inode *dir, struct dentry *dentry)
 
 	dget(dentry);
 	ret = simple_rmdir(dir, dentry);
+	d_drop(dentry);
 	if (!ret)
 		fsnotify_rmdir(dir, dentry);
-	d_delete(dentry);
 	dput(dentry);
 	return ret;
 }
@@ -613,9 +613,9 @@ static int __rpc_unlink(struct inode *dir, struct dentry *dentry)
 
 	dget(dentry);
 	ret = simple_unlink(dir, dentry);
+	d_drop(dentry);
 	if (!ret)
 		fsnotify_unlink(dir, dentry);
-	d_delete(dentry);
 	dput(dentry);
 	return ret;
 }