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: Steve French <stfrench@microsoft.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 34d5397a1989..f58e4dc3987b 100644
--- a/fs/cifs/smb2pdu.c
+++ b/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;