fanotify: prepare to report both parent and child fid's

For some events, we are going to report both child and parent fid's,
so pass fsid and file handle as arguments to copy_fid_to_user(),
which is going to be called with parent and child file handles.

Link: https://lore.kernel.org/r/20200319151022.31456-13-amir73il@gmail.comSigned-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/notify/fanotify/fanotify_user.c

@@ -52,6 +52,13 @@ struct kmem_cache *fanotify_perm_event_cachep __read_mostly;
 
 #define FANOTIFY_EVENT_ALIGN 4
 
+static int fanotify_fid_info_len(int fh_len)
+{
+	return roundup(sizeof(struct fanotify_event_info_fid) +
+		       sizeof(struct file_handle) + fh_len,
+		       FANOTIFY_EVENT_ALIGN);
+}
+
 static int fanotify_event_info_len(struct fanotify_event *event)
 {
 	int fh_len = fanotify_event_object_fh_len(event);
@@ -59,9 +66,7 @@ static int fanotify_event_info_len(struct fanotify_event *event)
 	if (!fh_len)
 		return 0;
 
-	return roundup(sizeof(struct fanotify_event_info_fid) +
-		       sizeof(struct file_handle) + fh_len,
-		       FANOTIFY_EVENT_ALIGN);
+	return fanotify_fid_info_len(fh_len);
 }
 
 /*
@@ -199,14 +204,14 @@ static int process_access_response(struct fsnotify_group *group,
 	return -ENOENT;
 }
 
-static int copy_fid_to_user(struct fanotify_event *event, char __user *buf)
+static int copy_fid_to_user(__kernel_fsid_t *fsid, struct fanotify_fh *fh,
+			    char __user *buf)
 {
 	struct fanotify_event_info_fid info = { };
 	struct file_handle handle = { };
 	unsigned char bounce[FANOTIFY_INLINE_FH_LEN], *fh_buf;
-	struct fanotify_fh *fh = fanotify_event_object_fh(event);
 	size_t fh_len = fh->len;
-	size_t len = fanotify_event_info_len(event);
+	size_t len = fanotify_fid_info_len(fh_len);
 
 	if (!len)
 		return 0;
@@ -217,7 +222,7 @@ static int copy_fid_to_user(struct fanotify_event *event, char __user *buf)
 	/* Copy event info fid header followed by vaiable sized file handle */
 	info.hdr.info_type = FAN_EVENT_INFO_TYPE_FID;
 	info.hdr.len = len;
-	info.fsid = *fanotify_event_fsid(event);
+	info.fsid = *fsid;
 	if (copy_to_user(buf, &info, sizeof(info)))
 		return -EFAULT;
 
@@ -296,7 +301,9 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group,
 	if (f) {
 		fd_install(fd, f);
 	} else if (fanotify_event_has_fid(event)) {
-		ret = copy_fid_to_user(event, buf + FAN_EVENT_METADATA_LEN);
+		ret = copy_fid_to_user(fanotify_event_fsid(event),
+				       fanotify_event_object_fh(event),
+				       buf + FAN_EVENT_METADATA_LEN);
 		if (ret < 0)
 			return ret;
 	}