fsnotify: generalize handling of extra event flags

FS_EVENT_ON_CHILD gets a special treatment in fsnotify() because it is
not a flag specifying an event type, but rather an extra flags that may
be reported along with another event and control the handling of the
event by the backend.

FS_ISDIR is also an "extra flag" and not an "event type" and therefore
desrves the same treatment. With inotify/dnotify backends it was never
possible to set FS_ISDIR in mark masks, so it did not matter.
With fanotify backend, mark adding code jumps through hoops to avoid
setting the FS_ISDIR in the commulative object mask.

Separate the constant ALL_FSNOTIFY_EVENTS to ALL_FSNOTIFY_FLAGS and
ALL_FSNOTIFY_EVENTS, so the latter can be used to test for specific
event types.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/notify/fsnotify.c

@@ -196,7 +196,7 @@ static int send_to_group(struct inode *to_tell,
 			 struct fsnotify_iter_info *iter_info)
 {
 	struct fsnotify_group *group = NULL;
-	__u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
+	__u32 test_mask = (mask & ALL_FSNOTIFY_EVENTS);
 	__u32 marks_mask = 0;
 	__u32 marks_ignored_mask = 0;
 	struct fsnotify_mark *mark;
@@ -329,8 +329,7 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
 	struct mount *mnt = NULL;
 	__u32 mnt_or_sb_mask = 0;
 	int ret = 0;
-	/* global tests shouldn't care about events on child only the specific event */
-	__u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
+	__u32 test_mask = (mask & ALL_FSNOTIFY_EVENTS);
 
 	if (data_is == FSNOTIFY_EVENT_PATH) {
 		mnt = real_mount(((const struct path *)data)->mnt);
@@ -396,7 +395,7 @@ static __init int fsnotify_init(void)
 {
 	int ret;
 
-	BUG_ON(hweight32(ALL_FSNOTIFY_EVENTS) != 23);
+	BUG_ON(hweight32(ALL_FSNOTIFY_BITS) != 23);
 
 	ret = init_srcu_struct(&fsnotify_mark_srcu);
 	if (ret)

include/linux/fsnotify_backend.h

@@ -68,15 +68,20 @@
 
 #define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM)
 
+/* Events that can be reported to backends */
 #define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
 			     FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN | \
 			     FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE | \
 			     FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \
 			     FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
-			     FS_OPEN_PERM | FS_ACCESS_PERM | FS_EXCL_UNLINK | \
-			     FS_ISDIR | FS_IN_ONESHOT | FS_DN_RENAME | \
+			     FS_OPEN_PERM | FS_ACCESS_PERM | FS_DN_RENAME)
+
+/* Extra flags that may be reported with event or control handling of events */
+#define ALL_FSNOTIFY_FLAGS  (FS_EXCL_UNLINK | FS_ISDIR | FS_IN_ONESHOT | \
 			     FS_DN_MULTISHOT | FS_EVENT_ON_CHILD)
 
+#define ALL_FSNOTIFY_BITS   (ALL_FSNOTIFY_EVENTS | ALL_FSNOTIFY_FLAGS)
+
 struct fsnotify_group;
 struct fsnotify_event;
 struct fsnotify_mark;