#ifndef _FS_CEPH_MDS_CLIENT_H
  #define _FS_CEPH_MDS_CLIENT_H
  
  #include <linux/completion.h>
  #include <linux/kref.h>
  #include <linux/list.h>
  #include <linux/mutex.h>
  #include <linux/rbtree.h>
  #include <linux/spinlock.h>
  
  #include <linux/ceph/types.h>
  #include <linux/ceph/messenger.h>
  #include <linux/ceph/mdsmap.h>
  #include <linux/ceph/auth.h>
  
  /*
   * Some lock dependencies:
   *
   * session->s_mutex
   *         mdsc->mutex
   *
   *         mdsc->snap_rwsem
   *
   *         ci->i_ceph_lock
   *                 mdsc->snap_flush_lock
   *                 mdsc->cap_delay_lock
   *
   */
  
  struct ceph_fs_client;
  struct ceph_cap;
  
  /*
   * parsed info about a single inode.  pointers are into the encoded
   * on-wire structures within the mds reply message payload.
   */
  struct ceph_mds_reply_info_in {
  	struct ceph_mds_reply_inode *in;
  	struct ceph_dir_layout dir_layout;
  	u32 symlink_len;
  	char *symlink;
  	u32 xattr_len;
  	char *xattr_data;
  };
  
  /*
   * parsed info about an mds reply, including information about
   * either: 1) the target inode and/or its parent directory and dentry,
   * and directory contents (for readdir results), or
   * 2) the file range lock info (for fcntl F_GETLK results).
   */
  struct ceph_mds_reply_info_parsed {
  	struct ceph_mds_reply_head    *head;
  
  	/* trace */
  	struct ceph_mds_reply_info_in diri, targeti;
  	struct ceph_mds_reply_dirfrag *dirfrag;
  	char                          *dname;
  	u32                           dname_len;
  	struct ceph_mds_reply_lease   *dlease;
  
  	/* extra */
  	union {
  		/* for fcntl F_GETLK results */
  		struct ceph_filelock *filelock_reply;
  
  		/* for readdir results */
  		struct {
  			struct ceph_mds_reply_dirfrag *dir_dir;
  			int                           dir_nr;
  			char                          **dir_dname;
  			u32                           *dir_dname_len;
  			struct ceph_mds_reply_lease   **dir_dlease;
  			struct ceph_mds_reply_info_in *dir_in;
  			u8                            dir_complete, dir_end;
  		};
  
  		/* for create results */
  		struct {
  			bool has_create_ino;
  			u64 ino;
  		};
  	};
  
  	/* encoded blob describing snapshot contexts for certain
  	   operations (e.g., open) */
  	void *snapblob;
  	int snapblob_len;
  };
  
  
  /*
   * cap releases are batched and sent to the MDS en masse.
   */
  #define CEPH_CAPS_PER_RELEASE ((PAGE_CACHE_SIZE -			\
  				sizeof(struct ceph_mds_cap_release)) /	\
  			       sizeof(struct ceph_mds_cap_item))
  
  
  /*
   * state associated with each MDS<->client session
   */
  enum {
  	CEPH_MDS_SESSION_NEW = 1,
  	CEPH_MDS_SESSION_OPENING = 2,
  	CEPH_MDS_SESSION_OPEN = 3,
  	CEPH_MDS_SESSION_HUNG = 4,
  	CEPH_MDS_SESSION_CLOSING = 5,
  	CEPH_MDS_SESSION_RESTARTING = 6,
  	CEPH_MDS_SESSION_RECONNECTING = 7,
  };
  
  struct ceph_mds_session {
  	struct ceph_mds_client *s_mdsc;
  	int               s_mds;
  	int               s_state;
  	unsigned long     s_ttl;      /* time until mds kills us */
  	u64               s_seq;      /* incoming msg seq # */
  	struct mutex      s_mutex;    /* serialize session messages */
  
  	struct ceph_connection s_con;
  
  	struct ceph_auth_handshake s_auth;
  
  	/* protected by s_gen_ttl_lock */
  	spinlock_t        s_gen_ttl_lock;
  	u32               s_cap_gen;  /* inc each time we get mds stale msg */
  	unsigned long     s_cap_ttl;  /* when session caps expire */
  
  	/* protected by s_cap_lock */
  	spinlock_t        s_cap_lock;
  	struct list_head  s_caps;     /* all caps issued by this session */
  	int               s_nr_caps, s_trim_caps;
  	int               s_num_cap_releases;
  	int		  s_cap_reconnect;
  	struct list_head  s_cap_releases; /* waiting cap_release messages */
  	struct list_head  s_cap_releases_done; /* ready to send */
  	struct ceph_cap  *s_cap_iterator;
  
  	/* protected by mutex */
  	struct list_head  s_cap_flushing;     /* inodes w/ flushing caps */
  	struct list_head  s_cap_snaps_flushing;
  	unsigned long     s_renew_requested; /* last time we sent a renew req */
  	u64               s_renew_seq;
  
  	atomic_t          s_ref;
  	struct list_head  s_waiting;  /* waiting requests */
  	struct list_head  s_unsafe;   /* unsafe requests */
  };
  
  /*
   * modes of choosing which MDS to send a request to
   */
  enum {
  	USE_ANY_MDS,
  	USE_RANDOM_MDS,
  	USE_AUTH_MDS,   /* prefer authoritative mds for this metadata item */
  };
  
  struct ceph_mds_request;
  struct ceph_mds_client;
  
  /*
   * request completion callback
   */
  typedef void (*ceph_mds_request_callback_t) (struct ceph_mds_client *mdsc,
  					     struct ceph_mds_request *req);
  
  /*
   * an in-flight mds request
   */
  struct ceph_mds_request {
  	u64 r_tid;                   /* transaction id */
  	struct rb_node r_node;
  	struct ceph_mds_client *r_mdsc;
  
  	int r_op;                    /* mds op code */
  
  	/* operation on what? */
  	struct inode *r_inode;              /* arg1 */
  	struct dentry *r_dentry;            /* arg1 */
  	struct dentry *r_old_dentry;        /* arg2: rename from or link from */
  	struct inode *r_old_dentry_dir;     /* arg2: old dentry's parent dir */
  	char *r_path1, *r_path2;
  	struct ceph_vino r_ino1, r_ino2;
  
  	struct inode *r_locked_dir; /* dir (if any) i_mutex locked by vfs */
  	struct inode *r_target_inode;       /* resulting inode */
  
  	struct mutex r_fill_mutex;
  
  	union ceph_mds_request_args r_args;
  	int r_fmode;        /* file mode, if expecting cap */
  	kuid_t r_uid;
  	kgid_t r_gid;
  
  	/* for choosing which mds to send this request to */
  	int r_direct_mode;
  	u32 r_direct_hash;      /* choose dir frag based on this dentry hash */
  	bool r_direct_is_hash;  /* true if r_direct_hash is valid */
  
  	/* data payload is used for xattr ops */
  	struct page **r_pages;
  	int r_num_pages;
  	int r_data_len;
  
  	/* what caps shall we drop? */
  	int r_inode_drop, r_inode_unless;
  	int r_dentry_drop, r_dentry_unless;
  	int r_old_dentry_drop, r_old_dentry_unless;
  	struct inode *r_old_inode;
  	int r_old_inode_drop, r_old_inode_unless;
  
  	struct ceph_msg  *r_request;  /* original request */
  	int r_request_release_offset;
  	struct ceph_msg  *r_reply;
  	struct ceph_mds_reply_info_parsed r_reply_info;
  	int r_err;
  	bool r_aborted;
  
  	unsigned long r_timeout;  /* optional.  jiffies */
  	unsigned long r_started;  /* start time to measure timeout against */
  	unsigned long r_request_started; /* start time for mds request only,
  					    used to measure lease durations */
  
  	/* link unsafe requests to parent directory, for fsync */
  	struct inode	*r_unsafe_dir;
  	struct list_head r_unsafe_dir_item;
  
  	struct ceph_mds_session *r_session;
  
  	int               r_attempts;   /* resend attempts */
  	int               r_num_fwd;    /* number of forward attempts */
  	int               r_resend_mds; /* mds to resend to next, if any*/
  	u32               r_sent_on_mseq; /* cap mseq request was sent at*/
  
  	struct kref       r_kref;
  	struct list_head  r_wait;
  	struct completion r_completion;
  	struct completion r_safe_completion;
  	ceph_mds_request_callback_t r_callback;
  	struct list_head  r_unsafe_item;  /* per-session unsafe list item */
  	bool		  r_got_unsafe, r_got_safe, r_got_result;
  
  	bool              r_did_prepopulate;
  	u32               r_readdir_offset;
  
  	struct ceph_cap_reservation r_caps_reservation;
  	int r_num_caps;
  };
  
  /*
   * mds client state
   */
  struct ceph_mds_client {
  	struct ceph_fs_client  *fsc;
  	struct mutex            mutex;         /* all nested structures */
  
  	struct ceph_mdsmap      *mdsmap;
  	struct completion       safe_umount_waiters;
  	wait_queue_head_t       session_close_wq;
  	struct list_head        waiting_for_map;
  
  	struct ceph_mds_session **sessions;    /* NULL for mds if no session */
  	int                     max_sessions;  /* len of s_mds_sessions */
  	int                     stopping;      /* true if shutting down */
  
  	/*
  	 * snap_rwsem will cover cap linkage into snaprealms, and
  	 * realm snap contexts.  (later, we can do per-realm snap
  	 * contexts locks..)  the empty list contains realms with no
  	 * references (implying they contain no inodes with caps) that
  	 * should be destroyed.
  	 */
  	struct rw_semaphore     snap_rwsem;
  	struct rb_root          snap_realms;
  	struct list_head        snap_empty;
  	spinlock_t              snap_empty_lock;  /* protect snap_empty */
  
  	u64                    last_tid;      /* most recent mds request */
  	struct rb_root         request_tree;  /* pending mds requests */
  	struct delayed_work    delayed_work;  /* delayed work */
  	unsigned long    last_renew_caps;  /* last time we renewed our caps */
  	struct list_head cap_delay_list;   /* caps with delayed release */
  	spinlock_t       cap_delay_lock;   /* protects cap_delay_list */
  	struct list_head snap_flush_list;  /* cap_snaps ready to flush */
  	spinlock_t       snap_flush_lock;
  
  	u64               cap_flush_seq;
  	struct list_head  cap_dirty;        /* inodes with dirty caps */
  	struct list_head  cap_dirty_migrating; /* ...that are migration... */
  	int               num_cap_flushing; /* # caps we are flushing */
  	spinlock_t        cap_dirty_lock;   /* protects above items */
  	wait_queue_head_t cap_flushing_wq;
  
  	/*
  	 * Cap reservations
  	 *
  	 * Maintain a global pool of preallocated struct ceph_caps, referenced
  	 * by struct ceph_caps_reservations.  This ensures that we preallocate
  	 * memory needed to successfully process an MDS response.  (If an MDS
  	 * sends us cap information and we fail to process it, we will have
  	 * problems due to the client and MDS being out of sync.)
  	 *
  	 * Reservations are 'owned' by a ceph_cap_reservation context.
  	 */
  	spinlock_t	caps_list_lock;
  	struct		list_head caps_list; /* unused (reserved or
  						unreserved) */
  	int		caps_total_count;    /* total caps allocated */
  	int		caps_use_count;      /* in use */
  	int		caps_reserve_count;  /* unused, reserved */
  	int		caps_avail_count;    /* unused, unreserved */
  	int		caps_min_count;      /* keep at least this many
  						(unreserved) */
  	spinlock_t	  dentry_lru_lock;
  	struct list_head  dentry_lru;
  	int		  num_dentry;
  };
  
  extern const char *ceph_mds_op_name(int op);
  
  extern struct ceph_mds_session *
  __ceph_lookup_mds_session(struct ceph_mds_client *, int mds);
  
  static inline struct ceph_mds_session *
  ceph_get_mds_session(struct ceph_mds_session *s)
  {
  	atomic_inc(&s->s_ref);
  	return s;
  }
  
  extern void ceph_put_mds_session(struct ceph_mds_session *s);
  
  extern int ceph_send_msg_mds(struct ceph_mds_client *mdsc,
  			     struct ceph_msg *msg, int mds);
  
  extern int ceph_mdsc_init(struct ceph_fs_client *fsc);
  extern void ceph_mdsc_close_sessions(struct ceph_mds_client *mdsc);
  extern void ceph_mdsc_destroy(struct ceph_fs_client *fsc);
  
  extern void ceph_mdsc_sync(struct ceph_mds_client *mdsc);
  
  extern void ceph_mdsc_lease_release(struct ceph_mds_client *mdsc,
  				    struct inode *inode,
  				    struct dentry *dn);
  
  extern void ceph_invalidate_dir_request(struct ceph_mds_request *req);
  
  extern struct ceph_mds_request *
  ceph_mdsc_create_request(struct ceph_mds_client *mdsc, int op, int mode);
  extern void ceph_mdsc_submit_request(struct ceph_mds_client *mdsc,
  				     struct ceph_mds_request *req);
  extern int ceph_mdsc_do_request(struct ceph_mds_client *mdsc,
  				struct inode *dir,
  				struct ceph_mds_request *req);
  static inline void ceph_mdsc_get_request(struct ceph_mds_request *req)
  {
  	kref_get(&req->r_kref);
  }
  extern void ceph_mdsc_release_request(struct kref *kref);
  static inline void ceph_mdsc_put_request(struct ceph_mds_request *req)
  {
  	kref_put(&req->r_kref, ceph_mdsc_release_request);
  }
  
  extern int ceph_add_cap_releases(struct ceph_mds_client *mdsc,
  				 struct ceph_mds_session *session);
  extern void ceph_send_cap_releases(struct ceph_mds_client *mdsc,
  				   struct ceph_mds_session *session);
  
  extern void ceph_mdsc_pre_umount(struct ceph_mds_client *mdsc);
  
  extern char *ceph_mdsc_build_path(struct dentry *dentry, int *plen, u64 *base,
  				  int stop_on_nosnap);
  
  extern void __ceph_mdsc_drop_dentry_lease(struct dentry *dentry);
  extern void ceph_mdsc_lease_send_msg(struct ceph_mds_session *session,
  				     struct inode *inode,
  				     struct dentry *dentry, char action,
  				     u32 seq);
  
  extern void ceph_mdsc_handle_map(struct ceph_mds_client *mdsc,
  				 struct ceph_msg *msg);
  
  extern struct ceph_mds_session *
  ceph_mdsc_open_export_target_session(struct ceph_mds_client *mdsc, int target);
  extern void ceph_mdsc_open_export_target_sessions(struct ceph_mds_client *mdsc,
  					  struct ceph_mds_session *session);
  
  #endif