include/net/9p/client.h

   1 /*
   2  * include/net/9p/client.h
   3  *
   4  * 9P Client Definitions
   5  *
   6  *  Copyright (C) 2008 by Eric Van Hensbergen <ericvh@gmail.com>
   7  *  Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License version 2
  11  *  as published by the Free Software Foundation.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to:
  20  *  Free Software Foundation
  21  *  51 Franklin Street, Fifth Floor
  22  *  Boston, MA  02111-1301  USA
  23  *
  24  */
  25
  26 #ifndef NET_9P_CLIENT_H
  27 #define NET_9P_CLIENT_H
  28
  29 /* Number of requests per row */
  30 #define P9_ROW_MAXTAG 255
  31
  32 /**
  33  * enum p9_trans_status - different states of underlying transports
  34  * @Connected: transport is connected and healthy
  35  * @Disconnected: transport has been disconnected
  36  * @Hung: transport is connected by wedged
  37  *
  38  * This enumeration details the various states a transport
  39  * instatiation can be in.
  40  */
  41
  42 enum p9_trans_status {
  43         Connected,
  44         Disconnected,
  45         Hung,
  46 };
  47
  48 /**
  49  * enum p9_req_status_t - virtio request status
  50  * @REQ_STATUS_IDLE: request slot unused
  51  * @REQ_STATUS_ALLOC: request has been allocated but not sent
  52  * @REQ_STATUS_UNSENT: request waiting to be sent
  53  * @REQ_STATUS_SENT: request sent to server
  54  * @REQ_STATUS_FLSH: a flush has been sent for this request
  55  * @REQ_STATUS_RCVD: response received from server
  56  * @REQ_STATUS_FLSHD: request has been flushed
  57  * @REQ_STATUS_ERROR: request encountered an error on the client side
  58  *
  59  * The @REQ_STATUS_IDLE state is used to mark a request slot as unused
  60  * but use is actually tracked by the idpool structure which handles tag
  61  * id allocation.
  62  *
  63  */
  64
  65 enum p9_req_status_t {
  66         REQ_STATUS_IDLE,
  67         REQ_STATUS_ALLOC,
  68         REQ_STATUS_UNSENT,
  69         REQ_STATUS_SENT,
  70         REQ_STATUS_FLSH,
  71         REQ_STATUS_RCVD,
  72         REQ_STATUS_FLSHD,
  73         REQ_STATUS_ERROR,
  74 };
  75
  76 /**
  77  * struct p9_req_t - request slots
  78  * @status: status of this request slot
  79  * @t_err: transport error
  80  * @wq: wait_queue for the client to block on for this request
  81  * @tc: the request fcall structure
  82  * @rc: the response fcall structure
  83  * @aux: transport specific data (provided for trans_fd migration)
  84  * @tag: tag on request (BUG: redundant)
  85  * @req_list: link for higher level objects to chain requests
  86  *
  87  * Transport use an array to track outstanding requests
  88  * instead of a list.  While this may incurr overhead during initial
  89  * allocation or expansion, it makes request lookup much easier as the
  90  * tag id is a index into an array.  (We use tag+1 so that we can accomodate
  91  * the -1 tag for the T_VERSION request).
  92  * This also has the nice effect of only having to allocate wait_queues
  93  * once, instead of constantly allocating and freeing them.  Its possible
  94  * other resources could benefit from this scheme as well.
  95  *
  96  */
  97
  98 struct p9_req_t {
  99         int status;
 100         int t_err;
 101         wait_queue_head_t *wq;
 102         struct p9_fcall *tc;
 103         struct p9_fcall *rc;
 104         u16 flush_tag;
 105         void *aux;
 106
 107         int tag;
 108         struct list_head req_list;
 109 };
 110
 111 /**
 112  * struct p9_client - per client instance state
 113  * @lock: protect @fidlist
 114  * @msize: maximum data size negotiated by protocol
 115  * @dotu: extension flags negotiated by protocol
 116  * @trans_mod: module API instantiated with this client
 117  * @trans: tranport instance state and API
 118  * @conn: connection state information used by trans_fd
 119  * @fidpool: fid handle accounting for session
 120  * @fidlist: List of active fid handles
 121  * @tagpool - transaction id accounting for session
 122  * @reqs - 2D array of requests
 123  * @max_tag - current maximum tag id allocated
 124  *
 125  * The client structure is used to keep track of various per-client
 126  * state that has been instantiated.
 127  * In order to minimize per-transaction overhead we use a
 128  * simple array to lookup requests instead of a hash table
 129  * or linked list.  In order to support larger number of
 130  * transactions, we make this a 2D array, allocating new rows
 131  * when we need to grow the total number of the transactions.
 132  *
 133  * Each row is 256 requests and we'll support up to 256 rows for
 134  * a total of 64k concurrent requests per session.
 135  *
 136  * Bugs: duplicated data and potentially unnecessary elements.
 137  */
 138
 139 struct p9_client {
 140         spinlock_t lock; /* protect client structure */
 141         int msize;
 142         unsigned char dotu;
 143         struct p9_trans_module *trans_mod;
 144         enum p9_trans_status status;
 145         void *trans;
 146         struct p9_conn *conn;
 147
 148         struct p9_idpool *fidpool;
 149         struct list_head fidlist;
 150
 151         struct p9_idpool *tagpool;
 152         struct p9_req_t *reqs[P9_ROW_MAXTAG];
 153         int max_tag;
 154 };
 155
 156 /**
 157  * struct p9_fid - file system entity handle
 158  * @clnt: back pointer to instantiating &p9_client
 159  * @fid: numeric identifier for this handle
 160  * @mode: current mode of this fid (enum?)
 161  * @qid: the &p9_qid server identifier this handle points to
 162  * @iounit: the server reported maximum transaction size for this file
 163  * @uid: the numeric uid of the local user who owns this handle
 164  * @aux: transport specific information (unused?)
 165  * @rdir_fpos: tracks offset of file position when reading directory contents
 166  * @flist: per-client-instance fid tracking
 167  * @dlist: per-dentry fid tracking
 168  *
 169  * TODO: This needs lots of explanation.
 170  */
 171
 172 struct p9_fid {
 173         struct p9_client *clnt;
 174         u32 fid;
 175         int mode;
 176         struct p9_qid qid;
 177         u32 iounit;
 178         uid_t uid;
 179         void *aux;
 180
 181         int rdir_fpos;
 182         struct list_head flist;
 183         struct list_head dlist; /* list of all fids attached to a dentry */
 184 };
 185
 186 struct p9_client *p9_client_create(const char *dev_name, char *options);
 187 void p9_client_destroy(struct p9_client *clnt);
 188 void p9_client_disconnect(struct p9_client *clnt);
 189 struct p9_fid *p9_client_attach(struct p9_client *clnt, struct p9_fid *afid,
 190                                         char *uname, u32 n_uname, char *aname);
 191 struct p9_fid *p9_client_auth(struct p9_client *clnt, char *uname,
 192                                                 u32 n_uname, char *aname);
 193 struct p9_fid *p9_client_walk(struct p9_fid *oldfid, int nwname, char **wnames,
 194                                                                 int clone);
 195 int p9_client_open(struct p9_fid *fid, int mode);
 196 int p9_client_fcreate(struct p9_fid *fid, char *name, u32 perm, int mode,
 197                                                         char *extension);
 198 int p9_client_clunk(struct p9_fid *fid);
 199 int p9_client_remove(struct p9_fid *fid);
 200 int p9_client_read(struct p9_fid *fid, char *data, char __user *udata,
 201                                                         u64 offset, u32 count);
 202 int p9_client_write(struct p9_fid *fid, char *data, const char __user *udata,
 203                                                         u64 offset, u32 count);
 204 struct p9_stat *p9_client_stat(struct p9_fid *fid);
 205 int p9_client_wstat(struct p9_fid *fid, struct p9_wstat *wst);
 206
 207 struct p9_req_t *p9_tag_lookup(struct p9_client *, u16);
 208 void p9_client_cb(struct p9_client *c, struct p9_req_t *req);
 209
 210 #endif /* NET_9P_CLIENT_H */