/*
   * include/net/9p/client.h
   *
   * 9P Client Definitions
   *
   *  Copyright (C) 2008 by Eric Van Hensbergen <ericvh@gmail.com>
   *  Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
   *
   *  This program is free software; you can redistribute it and/or modify
   *  it under the terms of the GNU General Public License version 2
   *  as published by the Free Software Foundation.
   *
   *  This program is distributed in the hope that it will be useful,
   *  but WITHOUT ANY WARRANTY; without even the implied warranty of
   *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *  GNU General Public License for more details.
   *
   *  You should have received a copy of the GNU General Public License
   *  along with this program; if not, write to:
   *  Free Software Foundation
   *  51 Franklin Street, Fifth Floor
   *  Boston, MA  02111-1301  USA
   *
   */
  
  #ifndef NET_9P_CLIENT_H
  #define NET_9P_CLIENT_H
  
  #include <linux/utsname.h>
  
  /* Number of requests per row */
  #define P9_ROW_MAXTAG 255
  
  /** enum p9_proto_versions - 9P protocol versions
   * @p9_proto_legacy: 9P Legacy mode, pre-9P2000.u
   * @p9_proto_2000u: 9P2000.u extension
   * @p9_proto_2000L: 9P2000.L extension
   */
  
  enum p9_proto_versions{
  	p9_proto_legacy,
  	p9_proto_2000u,
  	p9_proto_2000L,
  };
  
  
  /**
   * enum p9_trans_status - different states of underlying transports
   * @Connected: transport is connected and healthy
   * @Disconnected: transport has been disconnected
   * @Hung: transport is connected by wedged
   *
   * This enumeration details the various states a transport
   * instatiation can be in.
   */
  
  enum p9_trans_status {
  	Connected,
  	BeginDisconnect,
  	Disconnected,
  	Hung,
  };
  
  /**
   * enum p9_req_status_t - status of a request
   * @REQ_STATUS_IDLE: request slot unused
   * @REQ_STATUS_ALLOC: request has been allocated but not sent
   * @REQ_STATUS_UNSENT: request waiting to be sent
   * @REQ_STATUS_SENT: request sent to server
   * @REQ_STATUS_FLSH: a flush has been sent for this request
   * @REQ_STATUS_RCVD: response received from server
   * @REQ_STATUS_FLSHD: request has been flushed
   * @REQ_STATUS_ERROR: request encountered an error on the client side
   *
   * The @REQ_STATUS_IDLE state is used to mark a request slot as unused
   * but use is actually tracked by the idpool structure which handles tag
   * id allocation.
   *
   */
  
  enum p9_req_status_t {
  	REQ_STATUS_IDLE,
  	REQ_STATUS_ALLOC,
  	REQ_STATUS_UNSENT,
  	REQ_STATUS_SENT,
  	REQ_STATUS_FLSH,
  	REQ_STATUS_RCVD,
  	REQ_STATUS_FLSHD,
  	REQ_STATUS_ERROR,
  };
  
  /**
   * struct p9_req_t - request slots
   * @status: status of this request slot
   * @t_err: transport error
   * @flush_tag: tag of request being flushed (for flush requests)
   * @wq: wait_queue for the client to block on for this request
   * @tc: the request fcall structure
   * @rc: the response fcall structure
   * @aux: transport specific data (provided for trans_fd migration)
   * @req_list: link for higher level objects to chain requests
   *
   * Transport use an array to track outstanding requests
   * instead of a list.  While this may incurr overhead during initial
   * allocation or expansion, it makes request lookup much easier as the
   * tag id is a index into an array.  (We use tag+1 so that we can accommodate
   * the -1 tag for the T_VERSION request).
   * This also has the nice effect of only having to allocate wait_queues
   * once, instead of constantly allocating and freeing them.  Its possible
   * other resources could benefit from this scheme as well.
   *
   */
  
  struct p9_req_t {
  	int status;
  	int t_err;
  	wait_queue_head_t *wq;
  	struct p9_fcall *tc;
  	struct p9_fcall *rc;
  	void *aux;
  
  	struct list_head req_list;
  };
  
  /**
   * struct p9_client - per client instance state
   * @lock: protect @fidlist
   * @msize: maximum data size negotiated by protocol
   * @dotu: extension flags negotiated by protocol
   * @proto_version: 9P protocol version to use
   * @trans_mod: module API instantiated with this client
   * @trans: tranport instance state and API
   * @conn: connection state information used by trans_fd
   * @fidpool: fid handle accounting for session
   * @fidlist: List of active fid handles
   * @tagpool - transaction id accounting for session
   * @reqs - 2D array of requests
   * @max_tag - current maximum tag id allocated
   * @name - node name used as client id
   *
   * The client structure is used to keep track of various per-client
   * state that has been instantiated.
   * In order to minimize per-transaction overhead we use a
   * simple array to lookup requests instead of a hash table
   * or linked list.  In order to support larger number of
   * transactions, we make this a 2D array, allocating new rows
   * when we need to grow the total number of the transactions.
   *
   * Each row is 256 requests and we'll support up to 256 rows for
   * a total of 64k concurrent requests per session.
   *
   * Bugs: duplicated data and potentially unnecessary elements.
   */
  
  struct p9_client {
  	spinlock_t lock; /* protect client structure */
  	unsigned int msize;
  	unsigned char proto_version;
  	struct p9_trans_module *trans_mod;
  	enum p9_trans_status status;
  	void *trans;
  	struct p9_conn *conn;
  
  	struct p9_idpool *fidpool;
  	struct list_head fidlist;
  
  	struct p9_idpool *tagpool;
  	struct p9_req_t *reqs[P9_ROW_MAXTAG];
  	int max_tag;
  
  	char name[__NEW_UTS_LEN + 1];
  };
  
  /**
   * struct p9_fid - file system entity handle
   * @clnt: back pointer to instantiating &p9_client
   * @fid: numeric identifier for this handle
   * @mode: current mode of this fid (enum?)
   * @qid: the &p9_qid server identifier this handle points to
   * @iounit: the server reported maximum transaction size for this file
   * @uid: the numeric uid of the local user who owns this handle
   * @rdir: readdir accounting structure (allocated on demand)
   * @flist: per-client-instance fid tracking
   * @dlist: per-dentry fid tracking
   *
   * TODO: This needs lots of explanation.
   */
  
  struct p9_fid {
  	struct p9_client *clnt;
  	u32 fid;
  	int mode;
  	struct p9_qid qid;
  	u32 iounit;
  	kuid_t uid;
  
  	void *rdir;
  
  	struct list_head flist;
  	struct hlist_node dlist;	/* list of all fids attached to a dentry */
  };
  
  /**
   * struct p9_dirent - directory entry structure
   * @qid: The p9 server qid for this dirent
   * @d_off: offset to the next dirent
   * @d_type: type of file
   * @d_name: file name
   */
  
  struct p9_dirent {
  	struct p9_qid qid;
  	u64 d_off;
  	unsigned char d_type;
  	char d_name[256];
  };
  
  int p9_client_statfs(struct p9_fid *fid, struct p9_rstatfs *sb);
  int p9_client_rename(struct p9_fid *fid, struct p9_fid *newdirfid,
  		     const char *name);
  int p9_client_renameat(struct p9_fid *olddirfid, const char *old_name,
  		       struct p9_fid *newdirfid, const char *new_name);
  struct p9_client *p9_client_create(const char *dev_name, char *options);
  void p9_client_destroy(struct p9_client *clnt);
  void p9_client_disconnect(struct p9_client *clnt);
  void p9_client_begin_disconnect(struct p9_client *clnt);
  struct p9_fid *p9_client_attach(struct p9_client *clnt, struct p9_fid *afid,
  				char *uname, kuid_t n_uname, char *aname);
  struct p9_fid *p9_client_walk(struct p9_fid *oldfid, uint16_t nwname,
  		char **wnames, int clone);
  int p9_client_open(struct p9_fid *fid, int mode);
  int p9_client_fcreate(struct p9_fid *fid, char *name, u32 perm, int mode,
  							char *extension);
  int p9_client_link(struct p9_fid *fid, struct p9_fid *oldfid, char *newname);
  int p9_client_symlink(struct p9_fid *fid, char *name, char *symname, kgid_t gid,
  							struct p9_qid *qid);
  int p9_client_create_dotl(struct p9_fid *ofid, char *name, u32 flags, u32 mode,
  		kgid_t gid, struct p9_qid *qid);
  int p9_client_clunk(struct p9_fid *fid);
  int p9_client_fsync(struct p9_fid *fid, int datasync);
  int p9_client_remove(struct p9_fid *fid);
  int p9_client_unlinkat(struct p9_fid *dfid, const char *name, int flags);
  int p9_client_read(struct p9_fid *fid, char *data, char __user *udata,
  							u64 offset, u32 count);
  int p9_client_write(struct p9_fid *fid, char *data, const char __user *udata,
  							u64 offset, u32 count);
  int p9_client_readdir(struct p9_fid *fid, char *data, u32 count, u64 offset);
  int p9dirent_read(struct p9_client *clnt, char *buf, int len,
  		  struct p9_dirent *dirent);
  struct p9_wstat *p9_client_stat(struct p9_fid *fid);
  int p9_client_wstat(struct p9_fid *fid, struct p9_wstat *wst);
  int p9_client_setattr(struct p9_fid *fid, struct p9_iattr_dotl *attr);
  
  struct p9_stat_dotl *p9_client_getattr_dotl(struct p9_fid *fid,
  							u64 request_mask);
  
  int p9_client_mknod_dotl(struct p9_fid *oldfid, char *name, int mode,
  			dev_t rdev, kgid_t gid, struct p9_qid *);
  int p9_client_mkdir_dotl(struct p9_fid *fid, char *name, int mode,
  				kgid_t gid, struct p9_qid *);
  int p9_client_lock_dotl(struct p9_fid *fid, struct p9_flock *flock, u8 *status);
  int p9_client_getlock_dotl(struct p9_fid *fid, struct p9_getlock *fl);
  struct p9_req_t *p9_tag_lookup(struct p9_client *, u16);
  void p9_client_cb(struct p9_client *c, struct p9_req_t *req);
  
  int p9_parse_header(struct p9_fcall *, int32_t *, int8_t *, int16_t *, int);
  int p9stat_read(struct p9_client *, char *, int, struct p9_wstat *);
  void p9stat_free(struct p9_wstat *);
  
  int p9_is_proto_dotu(struct p9_client *clnt);
  int p9_is_proto_dotl(struct p9_client *clnt);
  struct p9_fid *p9_client_xattrwalk(struct p9_fid *, const char *, u64 *);
  int p9_client_xattrcreate(struct p9_fid *, const char *, u64, int);
  int p9_client_readlink(struct p9_fid *fid, char **target);
  
  #endif /* NET_9P_CLIENT_H */