fanotify: don't recalculate a marks mask if only the ignored mask changed

If removing bits from a mark's ignored mask, the concerning
inodes/vfsmounts mask is not affected.  So don't recalculate it.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NLino Sanfilippo <LinoSanfilippo@gmx.de>
Reviewed-by: NJan Kara <jack@suse.cz>
Cc: Eric Paris <eparis@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

fs/notify/fanotify/fanotify_user.c

@@ -487,15 +487,16 @@ static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
 					    unsigned int flags,
 					    int *destroy)
 {
-	__u32 oldmask;
+	__u32 oldmask = 0;
 
 	spin_lock(&fsn_mark->lock);
 	if (!(flags & FAN_MARK_IGNORED_MASK)) {
 		oldmask = fsn_mark->mask;
 		fsnotify_set_mark_mask_locked(fsn_mark, (oldmask & ~mask));
 	} else {
-		oldmask = fsn_mark->ignored_mask;
-		fsnotify_set_mark_ignored_mask_locked(fsn_mark, (oldmask & ~mask));
+		__u32 tmask = fsn_mark->ignored_mask & ~mask;
+
+		fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
 	}
 	*destroy = !(fsn_mark->mask | fsn_mark->ignored_mask);
 	spin_unlock(&fsn_mark->lock);