fsnotify: parent event notification

inotify and dnotify both use a similar parent notification mechanism.  We
add a generic parent notification mechanism to fsnotify for both of these
to use.  This new machanism also adds the dentry flag optimization which
exists for inotify to dnotify.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>

1 files changed, 17 insertions, 0 deletions

diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index cdc154146974..a39534845b28 100644
--- a/fs/notify/inode_mark.c
+++ b/fs/notify/inode_mark.c
@@ -131,6 +131,8 @@ void fsnotify_recalc_inode_mask(struct inode *inode)
         spin_lock(&inode->i_lock);
         fsnotify_recalc_inode_mask_locked(inode);
         spin_unlock(&inode->i_lock);
+
+        __fsnotify_update_child_dentry_flags(inode);
 }
 
 /*
@@ -190,6 +192,19 @@ void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry)
         group->ops->freeing_mark(entry, group);
 
         /*
+         * __fsnotify_update_child_dentry_flags(inode);
+         *
+         * I really want to call that, but we can't, we have no idea if the inode
+         * still exists the second we drop the entry->lock.
+         *
+         * The next time an event arrive to this inode from one of it's children
+         * __fsnotify_parent will see that the inode doesn't care about it's
+         * children and will update all of these flags then.  So really this
+         * is just a lazy update (and could be a perf win...)
+         */
+
+
+        /*
          * it's possible that this group tried to destroy itself, but this
          * this mark was simultaneously being freed by inode.  If that's the
          * case, we finish freeing the group here.
@@ -323,6 +338,8 @@ int fsnotify_add_mark(struct fsnotify_mark_entry *entry,
         if (lentry) {
                 ret = -EEXIST;
                 fsnotify_put_mark(lentry);
+        } else {
+                __fsnotify_update_child_dentry_flags(inode);
         }
 
         return ret;