#ifndef __FS_CEPH_MESSENGER_H
  #define __FS_CEPH_MESSENGER_H
  
  #include <linux/blk_types.h>
  #include <linux/kref.h>
  #include <linux/mutex.h>
  #include <linux/net.h>
  #include <linux/radix-tree.h>
  #include <linux/uio.h>
  #include <linux/workqueue.h>
  
  #include <linux/ceph/types.h>
  #include <linux/ceph/buffer.h>
  
  struct ceph_msg;
  struct ceph_connection;
  
  /*
   * Ceph defines these callbacks for handling connection events.
   */
  struct ceph_connection_operations {
  	struct ceph_connection *(*get)(struct ceph_connection *);
  	void (*put)(struct ceph_connection *);
  
  	/* handle an incoming message. */
  	void (*dispatch) (struct ceph_connection *con, struct ceph_msg *m);
  
  	/* authorize an outgoing connection */
  	struct ceph_auth_handshake *(*get_authorizer) (
  				struct ceph_connection *con,
  			       int *proto, int force_new);
  	int (*verify_authorizer_reply) (struct ceph_connection *con, int len);
  	int (*invalidate_authorizer)(struct ceph_connection *con);
  
  	/* there was some error on the socket (disconnect, whatever) */
  	void (*fault) (struct ceph_connection *con);
  
  	/* a remote host as terminated a message exchange session, and messages
  	 * we sent (or they tried to send us) may be lost. */
  	void (*peer_reset) (struct ceph_connection *con);
  
  	struct ceph_msg * (*alloc_msg) (struct ceph_connection *con,
  					struct ceph_msg_header *hdr,
  					int *skip);
  };
  
  /* use format string %s%d */
  #define ENTITY_NAME(n) ceph_entity_type_name((n).type), le64_to_cpu((n).num)
  
  struct ceph_messenger {
  	struct ceph_entity_inst inst;    /* my name+address */
  	struct ceph_entity_addr my_enc_addr;
  
  	atomic_t stopping;
  	bool nocrc;
  
  	/*
  	 * the global_seq counts connections i (attempt to) initiate
  	 * in order to disambiguate certain connect race conditions.
  	 */
  	u32 global_seq;
  	spinlock_t global_seq_lock;
  
  	u64 supported_features;
  	u64 required_features;
  };
  
  enum ceph_msg_data_type {
  	CEPH_MSG_DATA_NONE,	/* message contains no data payload */
  	CEPH_MSG_DATA_PAGES,	/* data source/destination is a page array */
  	CEPH_MSG_DATA_PAGELIST,	/* data source/destination is a pagelist */
  #ifdef CONFIG_BLOCK
  	CEPH_MSG_DATA_BIO,	/* data source/destination is a bio list */
  #endif /* CONFIG_BLOCK */
  };
  
  static __inline__ bool ceph_msg_data_type_valid(enum ceph_msg_data_type type)
  {
  	switch (type) {
  	case CEPH_MSG_DATA_NONE:
  	case CEPH_MSG_DATA_PAGES:
  	case CEPH_MSG_DATA_PAGELIST:
  #ifdef CONFIG_BLOCK
  	case CEPH_MSG_DATA_BIO:
  #endif /* CONFIG_BLOCK */
  		return true;
  	default:
  		return false;
  	}
  }
  
  struct ceph_msg_data {
  	struct list_head		links;	/* ceph_msg->data */
  	enum ceph_msg_data_type		type;
  	union {
  #ifdef CONFIG_BLOCK
  		struct {
  			struct bio	*bio;
  			size_t		bio_length;
  		};
  #endif /* CONFIG_BLOCK */
  		struct {
  			struct page	**pages;	/* NOT OWNER. */
  			size_t		length;		/* total # bytes */
  			unsigned int	alignment;	/* first page */
  		};
  		struct ceph_pagelist	*pagelist;
  	};
  };
  
  struct ceph_msg_data_cursor {
  	size_t			total_resid;	/* across all data items */
  	struct list_head	*data_head;	/* = &ceph_msg->data */
  
  	struct ceph_msg_data	*data;		/* current data item */
  	size_t			resid;		/* bytes not yet consumed */
  	bool			last_piece;	/* current is last piece */
  	bool			need_crc;	/* crc update needed */
  	union {
  #ifdef CONFIG_BLOCK
  		struct {				/* bio */
  			struct bio	*bio;		/* bio from list */
  			struct bvec_iter bvec_iter;
  		};
  #endif /* CONFIG_BLOCK */
  		struct {				/* pages */
  			unsigned int	page_offset;	/* offset in page */
  			unsigned short	page_index;	/* index in array */
  			unsigned short	page_count;	/* pages in array */
  		};
  		struct {				/* pagelist */
  			struct page	*page;		/* page from list */
  			size_t		offset;		/* bytes from list */
  		};
  	};
  };
  
  /*
   * a single message.  it contains a header (src, dest, message type, etc.),
   * footer (crc values, mainly), a "front" message body, and possibly a
   * data payload (stored in some number of pages).
   */
  struct ceph_msg {
  	struct ceph_msg_header hdr;	/* header */
  	struct ceph_msg_footer footer;	/* footer */
  	struct kvec front;              /* unaligned blobs of message */
  	struct ceph_buffer *middle;
  
  	size_t				data_length;
  	struct list_head		data;
  	struct ceph_msg_data_cursor	cursor;
  
  	struct ceph_connection *con;
  	struct list_head list_head;	/* links for connection lists */
  
  	struct kref kref;
  	bool more_to_follow;
  	bool needs_out_seq;
  	int front_alloc_len;
  	unsigned long ack_stamp;        /* tx: when we were acked */
  
  	struct ceph_msgpool *pool;
  };
  
  /* ceph connection fault delay defaults, for exponential backoff */
  #define BASE_DELAY_INTERVAL	(HZ/2)
  #define MAX_DELAY_INTERVAL	(5 * 60 * HZ)
  
  /*
   * A single connection with another host.
   *
   * We maintain a queue of outgoing messages, and some session state to
   * ensure that we can preserve the lossless, ordered delivery of
   * messages in the case of a TCP disconnect.
   */
  struct ceph_connection {
  	void *private;
  
  	const struct ceph_connection_operations *ops;
  
  	struct ceph_messenger *msgr;
  
  	atomic_t sock_state;
  	struct socket *sock;
  	struct ceph_entity_addr peer_addr; /* peer address */
  	struct ceph_entity_addr peer_addr_for_me;
  
  	unsigned long flags;
  	unsigned long state;
  	const char *error_msg;  /* error message, if any */
  
  	struct ceph_entity_name peer_name; /* peer name */
  
  	u64 peer_features;
  	u32 connect_seq;      /* identify the most recent connection
  				 attempt for this connection, client */
  	u32 peer_global_seq;  /* peer's global seq for this connection */
  
  	int auth_retry;       /* true if we need a newer authorizer */
  	void *auth_reply_buf;   /* where to put the authorizer reply */
  	int auth_reply_buf_len;
  
  	struct mutex mutex;
  
  	/* out queue */
  	struct list_head out_queue;
  	struct list_head out_sent;   /* sending or sent but unacked */
  	u64 out_seq;		     /* last message queued for send */
  
  	u64 in_seq, in_seq_acked;  /* last message received, acked */
  
  	/* connection negotiation temps */
  	char in_banner[CEPH_BANNER_MAX_LEN];
  	struct ceph_msg_connect out_connect;
  	struct ceph_msg_connect_reply in_reply;
  	struct ceph_entity_addr actual_peer_addr;
  
  	/* message out temps */
  	struct ceph_msg *out_msg;        /* sending message (== tail of
  					    out_sent) */
  	bool out_msg_done;
  
  	struct kvec out_kvec[8],         /* sending header/footer data */
  		*out_kvec_cur;
  	int out_kvec_left;   /* kvec's left in out_kvec */
  	int out_skip;        /* skip this many bytes */
  	int out_kvec_bytes;  /* total bytes left */
  	bool out_kvec_is_msg; /* kvec refers to out_msg */
  	int out_more;        /* there is more data after the kvecs */
  	__le64 out_temp_ack; /* for writing an ack */
  
  	/* message in temps */
  	struct ceph_msg_header in_hdr;
  	struct ceph_msg *in_msg;
  	u32 in_front_crc, in_middle_crc, in_data_crc;  /* calculated crc */
  
  	char in_tag;         /* protocol control byte */
  	int in_base_pos;     /* bytes read */
  	__le64 in_temp_ack;  /* for reading an ack */
  
  	struct delayed_work work;	    /* send|recv work */
  	unsigned long       delay;          /* current delay interval */
  };
  
  
  extern const char *ceph_pr_addr(const struct sockaddr_storage *ss);
  extern int ceph_parse_ips(const char *c, const char *end,
  			  struct ceph_entity_addr *addr,
  			  int max_count, int *count);
  
  
  extern int ceph_msgr_init(void);
  extern void ceph_msgr_exit(void);
  extern void ceph_msgr_flush(void);
  
  extern void ceph_messenger_init(struct ceph_messenger *msgr,
  			struct ceph_entity_addr *myaddr,
  			u64 supported_features,
  			u64 required_features,
  			bool nocrc);
  
  extern void ceph_con_init(struct ceph_connection *con, void *private,
  			const struct ceph_connection_operations *ops,
  			struct ceph_messenger *msgr);
  extern void ceph_con_open(struct ceph_connection *con,
  			  __u8 entity_type, __u64 entity_num,
  			  struct ceph_entity_addr *addr);
  extern bool ceph_con_opened(struct ceph_connection *con);
  extern void ceph_con_close(struct ceph_connection *con);
  extern void ceph_con_send(struct ceph_connection *con, struct ceph_msg *msg);
  
  extern void ceph_msg_revoke(struct ceph_msg *msg);
  extern void ceph_msg_revoke_incoming(struct ceph_msg *msg);
  
  extern void ceph_con_keepalive(struct ceph_connection *con);
  
  extern void ceph_msg_data_add_pages(struct ceph_msg *msg, struct page **pages,
  				size_t length, size_t alignment);
  extern void ceph_msg_data_add_pagelist(struct ceph_msg *msg,
  				struct ceph_pagelist *pagelist);
  #ifdef CONFIG_BLOCK
  extern void ceph_msg_data_add_bio(struct ceph_msg *msg, struct bio *bio,
  				size_t length);
  #endif /* CONFIG_BLOCK */
  
  extern struct ceph_msg *ceph_msg_new(int type, int front_len, gfp_t flags,
  				     bool can_fail);
  extern void ceph_msg_kfree(struct ceph_msg *m);
  
  
  static inline struct ceph_msg *ceph_msg_get(struct ceph_msg *msg)
  {
  	kref_get(&msg->kref);
  	return msg;
  }
  extern void ceph_msg_last_put(struct kref *kref);
  static inline void ceph_msg_put(struct ceph_msg *msg)
  {
  	kref_put(&msg->kref, ceph_msg_last_put);
  }
  
  extern void ceph_msg_dump(struct ceph_msg *msg);
  
  #endif