fs/9p/fid.c

   1 /*
   2  * V9FS FID Management
   3  *
   4  *  Copyright (C) 2005 by Eric Van Hensbergen <ericvh@gmail.com>
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to:
  18  *  Free Software Foundation
  19  *  51 Franklin Street, Fifth Floor
  20  *  Boston, MA  02111-1301  USA
  21  *
  22  */
  23
  24 #include <linux/config.h>
  25 #include <linux/module.h>
  26 #include <linux/errno.h>
  27 #include <linux/fs.h>
  28 #include <linux/idr.h>
  29
  30 #include "debug.h"
  31 #include "v9fs.h"
  32 #include "9p.h"
  33 #include "v9fs_vfs.h"
  34 #include "transport.h"
  35 #include "mux.h"
  36 #include "conv.h"
  37 #include "fid.h"
  38
  39 /**
  40  * v9fs_fid_insert - add a fid to a dentry
  41  * @fid: fid to add
  42  * @dentry: dentry that it is being added to
  43  *
  44  */
  45
  46 static int v9fs_fid_insert(struct v9fs_fid *fid, struct dentry *dentry)
  47 {
  48         struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
  49         dprintk(DEBUG_9P, "fid %d (%p) dentry %s (%p)\n", fid->fid, fid,
  50                 dentry->d_iname, dentry);
  51         if (dentry->d_fsdata == NULL) {
  52                 dentry->d_fsdata =
  53                     kmalloc(sizeof(struct list_head), GFP_KERNEL);
  54                 if (dentry->d_fsdata == NULL) {
  55                         dprintk(DEBUG_ERROR, "Out of memory\n");
  56                         return -ENOMEM;
  57                 }
  58                 fid_list = (struct list_head *)dentry->d_fsdata;
  59                 INIT_LIST_HEAD(fid_list);       /* Initialize list head */
  60         }
  61
  62         fid->uid = current->uid;
  63         fid->pid = current->pid;
  64         list_add(&fid->list, fid_list);
  65         return 0;
  66 }
  67
  68 /**
  69  * v9fs_fid_create - allocate a FID structure
  70  * @dentry - dentry to link newly created fid to
  71  *
  72  */
  73
  74 struct v9fs_fid *v9fs_fid_create(struct dentry *dentry)
  75 {
  76         struct v9fs_fid *new;
  77
  78         new = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL);
  79         if (new == NULL) {
  80                 dprintk(DEBUG_ERROR, "Out of Memory\n");
  81                 return ERR_PTR(-ENOMEM);
  82         }
  83
  84         new->fid = -1;
  85         new->fidopen = 0;
  86         new->fidcreate = 0;
  87         new->fidclunked = 0;
  88         new->iounit = 0;
  89
  90         if (v9fs_fid_insert(new, dentry) == 0)
  91                 return new;
  92         else {
  93                 dprintk(DEBUG_ERROR, "Problems inserting to dentry\n");
  94                 kfree(new);
  95                 return NULL;
  96         }
  97 }
  98
  99 /**
 100  * v9fs_fid_destroy - deallocate a FID structure
 101  * @fid: fid to destroy
 102  *
 103  */
 104
 105 void v9fs_fid_destroy(struct v9fs_fid *fid)
 106 {
 107         list_del(&fid->list);
 108         kfree(fid);
 109 }
 110
 111 /**
 112  * v9fs_fid_lookup - retrieve the right fid from a  particular dentry
 113  * @dentry: dentry to look for fid in
 114  * @type: intent of lookup (operation or traversal)
 115  *
 116  * search list of fids associated with a dentry for a fid with a matching
 117  * thread id or uid.  If that fails, look up the dentry's parents to see if you
 118  * can find a matching fid.
 119  *
 120  */
 121
 122 struct v9fs_fid *v9fs_fid_lookup(struct dentry *dentry, int type)
 123 {
 124         struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
 125         struct v9fs_fid *current_fid = NULL;
 126         struct v9fs_fid *temp = NULL;
 127         struct v9fs_fid *return_fid = NULL;
 128         int found_parent = 0;
 129         int found_user = 0;
 130
 131         dprintk(DEBUG_9P, " dentry: %s (%p) type %d\n", dentry->d_iname, dentry,
 132                 type);
 133
 134         if (fid_list && !list_empty(fid_list)) {
 135                 list_for_each_entry_safe(current_fid, temp, fid_list, list) {
 136                         if (current_fid->uid == current->uid) {
 137                                 if (return_fid == NULL) {
 138                                         if ((type == FID_OP)
 139                                             || (!current_fid->fidopen)) {
 140                                                 return_fid = current_fid;
 141                                                 found_user = 1;
 142                                         }
 143                                 }
 144                         }
 145                         if (current_fid->pid == current->real_parent->pid) {
 146                                 if ((return_fid == NULL) || (found_parent)
 147                                     || (found_user)) {
 148                                         if ((type == FID_OP)
 149                                             || (!current_fid->fidopen)) {
 150                                                 return_fid = current_fid;
 151                                                 found_parent = 1;
 152                                                 found_user = 0;
 153                                         }
 154                                 }
 155                         }
 156                         if (current_fid->pid == current->pid) {
 157                                 if ((type == FID_OP) ||
 158                                     (!current_fid->fidopen)) {
 159                                         return_fid = current_fid;
 160                                         found_parent = 0;
 161                                         found_user = 0;
 162                                 }
 163                         }
 164                 }
 165         }
 166
 167         /* we are at the root but didn't match */
 168         if ((!return_fid) && (dentry->d_parent == dentry)) {
 169                 /* TODO: clone attach with new uid */
 170                 return_fid = current_fid;
 171         }
 172
 173         if (!return_fid) {
 174                 struct dentry *par = current->fs->pwd->d_parent;
 175                 int count = 1;
 176                 while (par != NULL) {
 177                         if (par == dentry)
 178                                 break;
 179                         count++;
 180                         if (par == par->d_parent) {
 181                                 dprintk(DEBUG_ERROR,
 182                                         "got to root without finding dentry\n");
 183                                 break;
 184                         }
 185                         par = par->d_parent;
 186                 }
 187
 188 /* XXX - there may be some duplication we can get rid of */
 189                 if (par == dentry) {
 190                         /* we need to fid_lookup the starting point */
 191                         int fidnum = -1;
 192                         int oldfid = -1;
 193                         int result = -1;
 194                         struct v9fs_session_info *v9ses =
 195                             v9fs_inode2v9ses(current->fs->pwd->d_inode);
 196
 197                         current_fid =
 198                             v9fs_fid_lookup(current->fs->pwd, FID_WALK);
 199                         if (current_fid == NULL) {
 200                                 dprintk(DEBUG_ERROR,
 201                                         "process cwd doesn't have a fid\n");
 202                                 return return_fid;
 203                         }
 204                         oldfid = current_fid->fid;
 205                         par = current->fs->pwd;
 206                         /* TODO: take advantage of multiwalk */
 207
 208                         fidnum = v9fs_get_idpool(&v9ses->fidpool);
 209                         if (fidnum < 0) {
 210                                 dprintk(DEBUG_ERROR,
 211                                         "could not get a new fid num\n");
 212                                 return return_fid;
 213                         }
 214
 215                         while (par != dentry) {
 216                                 result =
 217                                     v9fs_t_walk(v9ses, oldfid, fidnum, "..",
 218                                                 NULL);
 219                                 if (result < 0) {
 220                                         dprintk(DEBUG_ERROR,
 221                                                 "problem walking to parent\n");
 222
 223                                         break;
 224                                 }
 225                                 oldfid = fidnum;
 226                                 if (par == par->d_parent) {
 227                                         dprintk(DEBUG_ERROR,
 228                                                 "can't find dentry\n");
 229                                         break;
 230                                 }
 231                                 par = par->d_parent;
 232                         }
 233                         if (par == dentry) {
 234                                 return_fid = v9fs_fid_create(dentry);
 235                                 return_fid->fid = fidnum;
 236                         }
 237                 }
 238         }
 239
 240         return return_fid;
 241 }