[SMB3] Add worker function for smb3 change notify

From 727ac06cc7007afea729bff04ce44f54995a8743 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Sun, 15 Sep 2019 22:38:52 -0500
Subject: [PATCH] smb3: add missing worker function for SMB3 change notify

SMB3 change notify is important to allow applications to wait
on directory change events of different types (e.g. adding
and deleting files from others systems). Add worker functions
for this.

Acked-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/smb2pdu.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++
 fs/cifs/trace.h   |  3 ++
 2 files changed, 88 insertions(+)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index ce647cfdc04f..87066f1af12c 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -3175,6 +3175,91 @@  SMB2_get_srv_num(const unsigned int xid, struct cifs_tcon *tcon,
 			  (void **)&uniqueid, NULL);
 }
 
+/*
+ * CHANGE_NOTIFY Request is sent to get notifications on changes to a directory
+ * See MS-SMB2 2.2.35 and 2.2.36
+ */
+
+int
+SMB2_notify_init(const unsigned int xid, struct smb_rqst *rqst,
+		struct cifs_tcon *tcon, u64 persistent_fid, u64 volatile_fid,
+		u32 completion_filter, bool watch_tree)
+{
+	struct smb2_change_notify_req *req;
+	struct kvec *iov = rqst->rq_iov;
+	unsigned int total_len;
+	int rc;
+
+	rc = smb2_plain_req_init(SMB2_CHANGE_NOTIFY, tcon, (void **) &req, &total_len);
+	if (rc)
+		return rc;
+
+	req->PersistentFileId = persistent_fid;
+	req->VolatileFileId = volatile_fid;
+	req->OutputBufferLength = SMB2_MAX_BUFFER_SIZE - MAX_SMB2_HDR_SIZE;
+	req->CompletionFilter = cpu_to_le32(completion_filter);
+	if (watch_tree)
+		req->Flags = cpu_to_le16(SMB2_WATCH_TREE);
+	else
+		req->Flags = 0;
+
+	iov[0].iov_base = (char *)req;
+	iov[0].iov_len = total_len;
+
+	return 0;
+}
+
+int
+SMB2_change_notify(const unsigned int xid, struct cifs_tcon *tcon,
+		u64 persistent_fid, u64 volatile_fid, bool watch_tree,
+		u32 completion_filter)
+{
+	struct cifs_ses *ses = tcon->ses;
+	struct smb_rqst rqst;
+	struct kvec iov[1];
+	struct kvec rsp_iov = {NULL, 0};
+	int resp_buftype = CIFS_NO_BUFFER;
+	int flags = 0;
+	int rc = 0;
+
+	cifs_dbg(FYI, "change notify\n");
+	if (!ses || !(ses->server))
+		return -EIO;
+
+	if (smb3_encryption_required(tcon))
+		flags |= CIFS_TRANSFORM_REQ;
+
+	memset(&rqst, 0, sizeof(struct smb_rqst));
+	memset(&iov, 0, sizeof(iov));
+	rqst.rq_iov = iov;
+	rqst.rq_nvec = 1;
+
+	rc = SMB2_notify_init(xid, &rqst, tcon, persistent_fid, volatile_fid,
+			      completion_filter, watch_tree);
+	if (rc)
+		goto cnotify_exit;
+
+	trace_smb3_notify_enter(xid, persistent_fid, tcon->tid, ses->Suid,
+				(u8)watch_tree, completion_filter);
+	rc = cifs_send_recv(xid, ses, &rqst, &resp_buftype, flags, &rsp_iov);
+
+	if (rc != 0) {
+		cifs_stats_fail_inc(tcon, SMB2_CHANGE_NOTIFY_HE);
+		trace_smb3_notify_err(xid, persistent_fid, tcon->tid, ses->Suid,
+				(u8)watch_tree, completion_filter, rc);
+	} else
+		trace_smb3_notify_done(xid, persistent_fid, tcon->tid,
+				ses->Suid, (u8)watch_tree, completion_filter);
+
+ cnotify_exit:
+	if (rqst.rq_iov)
+		cifs_small_buf_release(rqst.rq_iov[0].iov_base); /* request */
+	free_rsp_buf(resp_buftype, rsp_iov.iov_base);
+	return rc;
+}
+
+
+
 /*
  * This is a no-op for now. We're not really interested in the reply, but
  * rather in the fact that the server sent one and that server->lstrp
diff --git a/fs/cifs/trace.h b/fs/cifs/trace.h
index f1339f4a2d07..e7e350b13d6a 100644
--- a/fs/cifs/trace.h
+++ b/fs/cifs/trace.h
@@ -235,6 +235,8 @@  DEFINE_EVENT(smb3_inf_enter_class, smb3_##name,    \
 
 DEFINE_SMB3_INF_ENTER_EVENT(query_info_enter);
 DEFINE_SMB3_INF_ENTER_EVENT(query_info_done);
+DEFINE_SMB3_INF_ENTER_EVENT(notify_enter);
+DEFINE_SMB3_INF_ENTER_EVENT(notify_done);
 
 DECLARE_EVENT_CLASS(smb3_inf_err_class,
 	TP_PROTO(unsigned int xid,
@@ -281,6 +283,7 @@  DEFINE_EVENT(smb3_inf_err_class, smb3_##name,    \
 
 DEFINE_SMB3_INF_ERR_EVENT(query_info_err);
 DEFINE_SMB3_INF_ERR_EVENT(set_info_err);
+DEFINE_SMB3_INF_ERR_EVENT(notify_err);
 DEFINE_SMB3_INF_ERR_EVENT(fsctl_err);
 
 DECLARE_EVENT_CLASS(smb3_inf_compound_enter_class,
-- 
2.20.1