ceph: make num_fwd and num_retry to __u32

The num_fwd in MClientRequestForward is int32_t, while the num_fwd
in ceph_mds_request_head is __u8. This is buggy when the num_fwd
is larger than 256 it will always be truncate to 0 again. But the
client couldn't recoginize this.

This will make them to __u32 instead. Because the old cephs will
directly copy the raw memories when decoding the reqeust's head,
so we need to make sure this kclient will be compatible with old
cephs. For newer cephs they will decode the requests depending
the version, which will be much simpler and easier to extend new
members.

Link: https://tracker.ceph.com/issues/62145Signed-off-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Reviewed-by: Milind Changire <mchangir@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/mds_client.h

@@ -32,8 +32,9 @@ enum ceph_feature_type {
 	CEPHFS_FEATURE_ALTERNATE_NAME,
 	CEPHFS_FEATURE_NOTIFY_SESSION_STATE,
 	CEPHFS_FEATURE_OP_GETVXATTR,
+	CEPHFS_FEATURE_32BITS_RETRY_FWD,
 
-	CEPHFS_FEATURE_MAX = CEPHFS_FEATURE_OP_GETVXATTR,
+	CEPHFS_FEATURE_MAX = CEPHFS_FEATURE_32BITS_RETRY_FWD,
 };
 
 #define CEPHFS_FEATURES_CLIENT_SUPPORTED {	\
@@ -47,6 +48,7 @@ enum ceph_feature_type {
 	CEPHFS_FEATURE_ALTERNATE_NAME,		\
 	CEPHFS_FEATURE_NOTIFY_SESSION_STATE,	\
 	CEPHFS_FEATURE_OP_GETVXATTR,		\
+	CEPHFS_FEATURE_32BITS_RETRY_FWD,	\
 }
 
 /*

include/linux/ceph/ceph_fs.h

@@ -486,7 +486,7 @@ union ceph_mds_request_args_ext {
 #define CEPH_MDS_FLAG_WANT_DENTRY	2 /* want dentry in reply */
 #define CEPH_MDS_FLAG_ASYNC		4 /* request is asynchronous */
 
-struct ceph_mds_request_head_old {
+struct ceph_mds_request_head_legacy {
 	__le64 oldest_client_tid;
 	__le32 mdsmap_epoch;           /* on client */
 	__le32 flags;                  /* CEPH_MDS_FLAG_* */
@@ -499,9 +499,9 @@ struct ceph_mds_request_head_old {
 	union ceph_mds_request_args args;
 } __attribute__ ((packed));
 
-#define CEPH_MDS_REQUEST_HEAD_VERSION  1
+#define CEPH_MDS_REQUEST_HEAD_VERSION  2
 
-struct ceph_mds_request_head {
+struct ceph_mds_request_head_old {
 	__le16 version;                /* struct version */
 	__le64 oldest_client_tid;
 	__le32 mdsmap_epoch;           /* on client */
@@ -515,6 +515,23 @@ struct ceph_mds_request_head {
 	union ceph_mds_request_args_ext args;
 } __attribute__ ((packed));
 
+struct ceph_mds_request_head {
+	__le16 version;                /* struct version */
+	__le64 oldest_client_tid;
+	__le32 mdsmap_epoch;           /* on client */
+	__le32 flags;                  /* CEPH_MDS_FLAG_* */
+	__u8 num_retry, num_fwd;       /* legacy count retry and fwd attempts */
+	__le16 num_releases;           /* # include cap/lease release records */
+	__le32 op;                     /* mds op code */
+	__le32 caller_uid, caller_gid;
+	__le64 ino;                    /* use this ino for openc, mkdir, mknod,
+					  etc. (if replaying) */
+	union ceph_mds_request_args_ext args;
+
+	__le32 ext_num_retry;          /* new count retry attempts */
+	__le32 ext_num_fwd;            /* new count fwd attempts */
+} __attribute__ ((packed));
+
 /* cap/lease release record */
 struct ceph_mds_request_release {
 	__le64 ino, cap_id;            /* ino and unique cap id */