SMB3: query inode number on open via create context

We can cut the number of roundtrips on open (may also
help some rename cases as well) by returning the inode
number in the SMB2 open request itself instead of
querying it afterwards via a query FILE_INTERNAL_INFO.
This should significantly improve the performance of
posix open.

Add SMB2_CREATE_QUERY_ON_DISK_ID create context request
on open calls so that when server supports this we
can save a roundtrip for QUERY_INFO on every open.

Follow on patch will add the response processing for
SMB2_CREATE_QUERY_ON_DISK_ID context and optimize
smb2_open_file to avoid the extra network roundtrip
on every posix open. This patch adds the context on
SMB2/SMB3 open requests.
Signed-off-by: NSteve French <stfrench@microsoft.com>

fs/cifs/smb2pdu.c

@@ -2118,6 +2118,48 @@ add_twarp_context(struct kvec *iov, unsigned int *num_iovec, __u64 timewarp)
 	return 0;
 }
 
+static struct crt_query_id_ctxt *
+create_query_id_buf(void)
+{
+	struct crt_query_id_ctxt *buf;
+
+	buf = kzalloc(sizeof(struct crt_query_id_ctxt), GFP_KERNEL);
+	if (!buf)
+		return NULL;
+
+	buf->ccontext.DataOffset = cpu_to_le16(0);
+	buf->ccontext.DataLength = cpu_to_le32(0);
+	buf->ccontext.NameOffset = cpu_to_le16(offsetof
+				(struct crt_query_id_ctxt, Name));
+	buf->ccontext.NameLength = cpu_to_le16(4);
+	/* SMB2_CREATE_QUERY_ON_DISK_ID is "QFid" */
+	buf->Name[0] = 'Q';
+	buf->Name[1] = 'F';
+	buf->Name[2] = 'i';
+	buf->Name[3] = 'd';
+	return buf;
+}
+
+/* See MS-SMB2 2.2.13.2.9 */
+static int
+add_query_id_context(struct kvec *iov, unsigned int *num_iovec)
+{
+	struct smb2_create_req *req = iov[0].iov_base;
+	unsigned int num = *num_iovec;
+
+	iov[num].iov_base = create_query_id_buf();
+	if (iov[num].iov_base == NULL)
+		return -ENOMEM;
+	iov[num].iov_len = sizeof(struct crt_query_id_ctxt);
+	if (!req->CreateContextsOffset)
+		req->CreateContextsOffset = cpu_to_le32(
+				sizeof(struct smb2_create_req) +
+				iov[num - 1].iov_len);
+	le32_add_cpu(&req->CreateContextsLength, sizeof(struct crt_query_id_ctxt));
+	*num_iovec = num + 1;
+	return 0;
+}
+
 static int
 alloc_path_with_tree_prefix(__le16 **out_path, int *out_size, int *out_len,
 			    const char *treename, const __le16 *path)
@@ -2446,6 +2488,12 @@ SMB2_open_init(struct cifs_tcon *tcon, struct smb_rqst *rqst, __u8 *oplock,
 			return rc;
 	}
 
+	if (n_iov > 2) {
+		struct create_context *ccontext =
+			(struct create_context *)iov[n_iov-1].iov_base;
+		ccontext->Next = cpu_to_le32(iov[n_iov-1].iov_len);
+	}
+	add_query_id_context(iov, &n_iov);
 
 	rqst->rq_nvec = n_iov;
 	return 0;

fs/cifs/smb2pdu.h

@@ -662,9 +662,10 @@ struct smb2_tree_disconnect_rsp {
  * [3] : durable context
  * [4] : posix context
  * [5] : time warp context
- * [6] : compound padding
+ * [6] : query id context
+ * [7] : compound padding
  */
-#define SMB2_CREATE_IOV_SIZE 7
+#define SMB2_CREATE_IOV_SIZE 8
 
 struct smb2_create_req {
 	struct smb2_sync_hdr sync_hdr;
@@ -688,10 +689,10 @@ struct smb2_create_req {
 
 /*
  * Maximum size of a SMB2_CREATE response is 64 (smb2 header) +
- * 88 (fixed part of create response) + 520 (path) + 150 (contexts) +
+ * 88 (fixed part of create response) + 520 (path) + 208 (contexts) +
  * 2 bytes of padding.
  */
-#define MAX_SMB2_CREATE_RESPONSE_SIZE 824
+#define MAX_SMB2_CREATE_RESPONSE_SIZE 880
 
 struct smb2_create_rsp {
 	struct smb2_sync_hdr sync_hdr;
@@ -818,7 +819,7 @@ struct durable_reconnect_context_v2 {
 struct on_disk_id {
 	__le64 DiskFileId;
 	__le64 VolumeId;
-	__u64  Reserved[4];
+	__u32  Reserved[4];
 } __packed;
 
 /* See MS-SMB2 2.2.14.2.12 */
@@ -841,6 +842,12 @@ struct crt_twarp_ctxt {
 
 } __packed;
 
+/* See MS-SMB2 2.2.13.2.9 */
+struct crt_query_id_ctxt {
+	struct create_context ccontext;
+	__u8	Name[8];
+} __packed;
+
 #define COPY_CHUNK_RES_KEY_SIZE	24
 struct resume_key_req {
 	char ResumeKey[COPY_CHUNK_RES_KEY_SIZE];