Merge: fsnotify: fix sending inotify event with unexpected filename

MR: https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-10/-/merge_requests/56

JIRA: https://issues.redhat.com/browse/RHEL-68847

Added upstream patch for a hang when using "tail -f" on a file under certain conditions.

Signed-off-by: Ian Kent <ikent@redhat.com>

Approved-by: Carlos Maiolino <cmaiolino@redhat.com>
Approved-by: Paulo Alcantara <paalcant@redhat.com>
Approved-by: CKI KWF Bot <cki-ci-bot+kwf-gitlab-com@redhat.com>

Merged-by: Jan Stancek <jstancek@redhat.com>

Author: jstancek

fs/notify/fsnotify.c

@@ -333,16 +333,19 @@ static int fsnotify_handle_event(struct fsnotify_group *group, __u32 mask,
 	if (!inode_mark)
 		return 0;
 
-	if (mask & FS_EVENT_ON_CHILD) {
-		/*
-		 * Some events can be sent on both parent dir and child marks
-		 * (e.g. FS_ATTRIB).  If both parent dir and child are
-		 * watching, report the event once to parent dir with name (if
-		 * interested) and once to child without name (if interested).
-		 * The child watcher is expecting an event without a file name
-		 * and without the FS_EVENT_ON_CHILD flag.
-		 */
-		mask &= ~FS_EVENT_ON_CHILD;
+	/*
+	 * Some events can be sent on both parent dir and child marks (e.g.
+	 * FS_ATTRIB).  If both parent dir and child are watching, report the
+	 * event once to parent dir with name (if interested) and once to child
+	 * without name (if interested).
+	 *
+	 * In any case regardless whether the parent is watching or not, the
+	 * child watcher is expecting an event without the FS_EVENT_ON_CHILD
+	 * flag. The file name is expected if and only if this is a directory
+	 * event.
+	 */
+	mask &= ~FS_EVENT_ON_CHILD;
+	if (!(mask & ALL_FSNOTIFY_DIRENT_EVENTS)) {
 		dir = NULL;
 		name = NULL;
 	}