Ask for time_delta during fsinfo probe

Used by the client to determine if the server has a granular enough
time stamp.
Signed-off-by: NRicardo Labiaga <Ricardo.Labiaga@netapp.com>
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/nfs4proc.c

@@ -129,7 +129,7 @@ const u32 nfs4_fsinfo_bitmap[2] = { FATTR4_WORD0_MAXFILESIZE
 			| FATTR4_WORD0_MAXREAD
 			| FATTR4_WORD0_MAXWRITE
 			| FATTR4_WORD0_LEASE_TIME,
-			0
+			FATTR4_WORD1_TIME_DELTA
 };
 
 const u32 nfs4_fs_locations_bitmap[2] = {

fs/nfs/nfs4xdr.c

@@ -3582,6 +3582,24 @@ static int decode_attr_time_metadata(struct xdr_stream *xdr, uint32_t *bitmap, s
 	return status;
 }
 
+static int decode_attr_time_delta(struct xdr_stream *xdr, uint32_t *bitmap,
+				  struct timespec *time)
+{
+	int status = 0;
+
+	time->tv_sec = 0;
+	time->tv_nsec = 0;
+	if (unlikely(bitmap[1] & (FATTR4_WORD1_TIME_DELTA - 1U)))
+		return -EIO;
+	if (likely(bitmap[1] & FATTR4_WORD1_TIME_DELTA)) {
+		status = decode_attr_time(xdr, time);
+		bitmap[1] &= ~FATTR4_WORD1_TIME_DELTA;
+	}
+	dprintk("%s: time_delta=%ld %ld\n", __func__, (long)time->tv_sec,
+		(long)time->tv_nsec);
+	return status;
+}
+
 static int decode_attr_time_modify(struct xdr_stream *xdr, uint32_t *bitmap, struct timespec *time)
 {
 	int status = 0;
@@ -3982,6 +4000,9 @@ static int decode_fsinfo(struct xdr_stream *xdr, struct nfs_fsinfo *fsinfo)
 	if ((status = decode_attr_maxwrite(xdr, bitmap, &fsinfo->wtmax)) != 0)
 		goto xdr_error;
 	fsinfo->wtpref = fsinfo->wtmax;
+	status = decode_attr_time_delta(xdr, bitmap, &fsinfo->time_delta);
+	if (status != 0)
+		goto xdr_error;
 
 	status = verify_attr_len(xdr, savep, attrlen);
 xdr_error: