ceph: update dentry lease for async create

Otherwise ceph_d_delete() may return 1 for the dentry, which makes
dput() prune the dentry and clear parent dir's complete flag.

Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/file.c

@@ -480,6 +480,9 @@ static int try_prep_async_create(struct inode *dir, struct dentry *dentry,
 	if (d_in_lookup(dentry)) {
 		if (!__ceph_dir_is_complete(ci))
 			goto no_async;
+		spin_lock(&dentry->d_lock);
+		di->lease_shared_gen = atomic_read(&ci->i_shared_gen);
+		spin_unlock(&dentry->d_lock);
 	} else if (atomic_read(&ci->i_shared_gen) !=
 		   READ_ONCE(di->lease_shared_gen)) {
 		goto no_async;