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-rw-r--r--fs/notify/fsnotify.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index dd3fb0b17be7..d675e76251d3 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -205,6 +205,16 @@ int fsnotify(struct inode *to_tell, __u32 mask, void *data, int data_is,
mnt = NULL;
/*
+ * Optimization: srcu_read_lock() has a memory barrier which can
+ * be expensive. It protects walking the *_fsnotify_marks lists.
+ * However, if we do not walk the lists, we do not have to do
+ * SRCU because we have no references to any objects and do not
+ * need SRCU to keep them "alive".
+ */
+ if (hlist_empty(&to_tell->i_fsnotify_marks) &&
+ (!mnt || hlist_empty(&mnt->mnt_fsnotify_marks)))
+ return 0;
+ /*
* if this is a modify event we may need to clear the ignored masks
* otherwise return if neither the inode nor the vfsmount care about
* this type of event.