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         struct v9fs_session_info *v9ses, int fid, int create)
  76 {
  77         struct v9fs_fid *new;
  78
  79         dprintk(DEBUG_9P, "fid create dentry %p, fid %d, create %d\n",
  80                 dentry, fid, create);
  81
  82         new = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL);
  83         if (new == NULL) {
  84                 dprintk(DEBUG_ERROR, "Out of Memory\n");
  85                 return ERR_PTR(-ENOMEM);
  86         }
  87
  88         new->fid = fid;
  89         new->v9ses = v9ses;
  90         new->fidopen = 0;
  91         new->fidcreate = create;
  92         new->fidclunked = 0;
  93         new->iounit = 0;
  94         new->rdir_pos = 0;
  95         new->rdir_fcall = NULL;
  96
  97         if (v9fs_fid_insert(new, dentry) == 0)
  98                 return new;
  99         else {
 100                 dprintk(DEBUG_ERROR, "Problems inserting to dentry\n");
 101                 kfree(new);
 102                 return NULL;
 103         }
 104 }
 105
 106 /**
 107  * v9fs_fid_destroy - deallocate a FID structure
 108  * @fid: fid to destroy
 109  *
 110  */
 111
 112 void v9fs_fid_destroy(struct v9fs_fid *fid)
 113 {
 114         list_del(&fid->list);
 115         kfree(fid);
 116 }
 117
 118 /**
 119  * v9fs_fid_walk_up - walks from the process current directory
 120  *      up to the specified dentry.
 121  */
 122 static struct v9fs_fid *v9fs_fid_walk_up(struct dentry *dentry)
 123 {
 124         int fidnum, cfidnum, err;
 125         struct v9fs_fid *cfid;
 126         struct dentry *cde;
 127         struct v9fs_session_info *v9ses;
 128
 129         v9ses = v9fs_inode2v9ses(current->fs->pwd->d_inode);
 130         cfid = v9fs_fid_lookup(current->fs->pwd);
 131         if (cfid == NULL) {
 132                 dprintk(DEBUG_ERROR, "process cwd doesn't have a fid\n");
 133                 return ERR_PTR(-ENOENT);
 134         }
 135
 136         cfidnum = cfid->fid;
 137         cde = current->fs->pwd;
 138         /* TODO: take advantage of multiwalk */
 139
 140         fidnum = v9fs_get_idpool(&v9ses->fidpool);
 141         if (fidnum < 0) {
 142                 dprintk(DEBUG_ERROR, "could not get a new fid num\n");
 143                 err = -ENOENT;
 144                 goto clunk_fid;
 145         }
 146
 147         while (cde != dentry) {
 148                 if (cde == cde->d_parent) {
 149                         dprintk(DEBUG_ERROR, "can't find dentry\n");
 150                         err = -ENOENT;
 151                         goto clunk_fid;
 152                 }
 153
 154                 err = v9fs_t_walk(v9ses, cfidnum, fidnum, "..", NULL);
 155                 if (err < 0) {
 156                         dprintk(DEBUG_ERROR, "problem walking to parent\n");
 157                         goto clunk_fid;
 158                 }
 159
 160                 cfidnum = fidnum;
 161                 cde = cde->d_parent;
 162         }
 163
 164         return v9fs_fid_create(dentry, v9ses, fidnum, 0);
 165
 166 clunk_fid:
 167         v9fs_t_clunk(v9ses, fidnum, NULL);
 168         return ERR_PTR(err);
 169 }
 170
 171 /**
 172  * v9fs_fid_lookup - retrieve the right fid from a  particular dentry
 173  * @dentry: dentry to look for fid in
 174  * @type: intent of lookup (operation or traversal)
 175  *
 176  * search list of fids associated with a dentry for a fid with a matching
 177  * thread id or uid.  If that fails, look up the dentry's parents to see if you
 178  * can find a matching fid.
 179  *
 180  */
 181
 182 struct v9fs_fid *v9fs_fid_lookup(struct dentry *dentry)
 183 {
 184         struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
 185         struct v9fs_fid *current_fid = NULL;
 186         struct v9fs_fid *temp = NULL;
 187         struct v9fs_fid *return_fid = NULL;
 188
 189         dprintk(DEBUG_9P, " dentry: %s (%p)\n", dentry->d_iname, dentry);
 190
 191         if (fid_list) {
 192                 list_for_each_entry_safe(current_fid, temp, fid_list, list) {
 193                         if (!current_fid->fidcreate) {
 194                                 return_fid = current_fid;
 195                                 break;
 196                         }
 197                 }
 198
 199                 if (!return_fid)
 200                         return_fid = current_fid;
 201         }
 202
 203         /* we are at the root but didn't match */
 204         if ((!return_fid) && (dentry->d_parent == dentry)) {
 205                 /* TODO: clone attach with new uid */
 206                 return_fid = current_fid;
 207         }
 208
 209         if (!return_fid) {
 210                 struct dentry *par = current->fs->pwd->d_parent;
 211                 int count = 1;
 212                 while (par != NULL) {
 213                         if (par == dentry)
 214                                 break;
 215                         count++;
 216                         if (par == par->d_parent) {
 217                                 dprintk(DEBUG_ERROR,
 218                                         "got to root without finding dentry\n");
 219                                 break;
 220                         }
 221                         par = par->d_parent;
 222                 }
 223
 224 /* XXX - there may be some duplication we can get rid of */
 225                 if (par == dentry) {
 226                         return_fid = v9fs_fid_walk_up(dentry);
 227                         if (IS_ERR(return_fid))
 228                                 return_fid = NULL;
 229                 }
 230         }
 231
 232         return return_fid;
 233 }
 234
 235 struct v9fs_fid *v9fs_fid_get_created(struct dentry *dentry)
 236 {
 237         struct list_head *fid_list;
 238         struct v9fs_fid *fid, *ftmp, *ret;
 239
 240         dprintk(DEBUG_9P, " dentry: %s (%p)\n", dentry->d_iname, dentry);
 241         fid_list = (struct list_head *)dentry->d_fsdata;
 242         ret = NULL;
 243         if (fid_list) {
 244                 list_for_each_entry_safe(fid, ftmp, fid_list, list) {
 245                         if (fid->fidcreate && fid->pid == current->pid) {
 246                                 list_del(&fid->list);
 247                                 ret = fid;
 248                                 break;
 249                         }
 250                 }
 251         }
 252
 253         dprintk(DEBUG_9P, "return %p\n", ret);
 254         return ret;
 255 }