fs/9p/fid.c

   1 /*
   2  * V9FS FID Management
   3  *
   4  *  Copyright (C) 2005, 2006 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 version 2
   8  *  as published by the Free Software Foundation.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, write to:
  17  *  Free Software Foundation
  18  *  51 Franklin Street, Fifth Floor
  19  *  Boston, MA  02111-1301  USA
  20  *
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/errno.h>
  25 #include <linux/fs.h>
  26 #include <linux/sched.h>
  27 #include <linux/idr.h>
  28 #include <asm/semaphore.h>
  29
  30 #include "debug.h"
  31 #include "v9fs.h"
  32 #include "9p.h"
  33 #include "v9fs_vfs.h"
  34 #include "fid.h"
  35
  36 /**
  37  * v9fs_fid_insert - add a fid to a dentry
  38  * @fid: fid to add
  39  * @dentry: dentry that it is being added to
  40  *
  41  */
  42
  43 int v9fs_fid_insert(struct v9fs_fid *fid, struct dentry *dentry)
  44 {
  45         struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
  46         dprintk(DEBUG_9P, "fid %d (%p) dentry %s (%p)\n", fid->fid, fid,
  47                 dentry->d_iname, dentry);
  48         if (dentry->d_fsdata == NULL) {
  49                 dentry->d_fsdata =
  50                     kmalloc(sizeof(struct list_head), GFP_KERNEL);
  51                 if (dentry->d_fsdata == NULL) {
  52                         dprintk(DEBUG_ERROR, "Out of memory\n");
  53                         return -ENOMEM;
  54                 }
  55                 fid_list = (struct list_head *)dentry->d_fsdata;
  56                 INIT_LIST_HEAD(fid_list);       /* Initialize list head */
  57         }
  58
  59         fid->uid = current->uid;
  60         list_add(&fid->list, fid_list);
  61         return 0;
  62 }
  63
  64 /**
  65  * v9fs_fid_create - allocate a FID structure
  66  * @dentry - dentry to link newly created fid to
  67  *
  68  */
  69
  70 struct v9fs_fid *v9fs_fid_create(struct v9fs_session_info *v9ses, int fid)
  71 {
  72         struct v9fs_fid *new;
  73
  74         dprintk(DEBUG_9P, "fid create fid %d\n", fid);
  75         new = kmalloc(sizeof(struct v9fs_fid), GFP_KERNEL);
  76         if (new == NULL) {
  77                 dprintk(DEBUG_ERROR, "Out of Memory\n");
  78                 return ERR_PTR(-ENOMEM);
  79         }
  80
  81         new->fid = fid;
  82         new->v9ses = v9ses;
  83         new->fidopen = 0;
  84         new->fidclunked = 0;
  85         new->iounit = 0;
  86         new->rdir_pos = 0;
  87         new->rdir_fcall = NULL;
  88         init_MUTEX(&new->lock);
  89         INIT_LIST_HEAD(&new->list);
  90
  91         return new;
  92 }
  93
  94 /**
  95  * v9fs_fid_destroy - deallocate a FID structure
  96  * @fid: fid to destroy
  97  *
  98  */
  99
 100 void v9fs_fid_destroy(struct v9fs_fid *fid)
 101 {
 102         list_del(&fid->list);
 103         kfree(fid);
 104 }
 105
 106 /**
 107  * v9fs_fid_lookup - return a locked fid from a dentry
 108  * @dentry: dentry to look for fid in
 109  *
 110  * find a fid in the dentry, obtain its semaphore and return a reference to it.
 111  * code calling lookup is responsible for releasing lock
 112  *
 113  * TODO: only match fids that have the same uid as current user
 114  *
 115  */
 116
 117 struct v9fs_fid *v9fs_fid_lookup(struct dentry *dentry)
 118 {
 119         struct list_head *fid_list = (struct list_head *)dentry->d_fsdata;
 120         struct v9fs_fid *return_fid = NULL;
 121
 122         dprintk(DEBUG_9P, " dentry: %s (%p)\n", dentry->d_iname, dentry);
 123
 124         if (fid_list)
 125                 return_fid = list_entry(fid_list->next, struct v9fs_fid, list);
 126
 127         if (!return_fid) {
 128                 dprintk(DEBUG_ERROR, "Couldn't find a fid in dentry\n");
 129                 return_fid = ERR_PTR(-EBADF);
 130         }
 131
 132         if(down_interruptible(&return_fid->lock))
 133                 return ERR_PTR(-EINTR);
 134
 135         return return_fid;
 136 }
 137
 138 /**
 139  * v9fs_fid_clone - lookup the fid for a dentry, clone a private copy and release it
 140  * @dentry: dentry to look for fid in
 141  *
 142  * find a fid in the dentry and then clone to a new private fid
 143  *
 144  * TODO: only match fids that have the same uid as current user
 145  *
 146  */
 147
 148 struct v9fs_fid *v9fs_fid_clone(struct dentry *dentry)
 149 {
 150         struct v9fs_session_info *v9ses = v9fs_inode2v9ses(dentry->d_inode);
 151         struct v9fs_fid *base_fid, *new_fid = ERR_PTR(-EBADF);
 152         struct v9fs_fcall *fcall = NULL;
 153         int fid, err;
 154
 155         base_fid = v9fs_fid_lookup(dentry);
 156
 157         if(IS_ERR(base_fid))
 158                 return base_fid;
 159
 160         if(base_fid) {  /* clone fid */
 161                 fid = v9fs_get_idpool(&v9ses->fidpool);
 162                 if (fid < 0) {
 163                         eprintk(KERN_WARNING, "newfid fails!\n");
 164                         new_fid = ERR_PTR(-ENOSPC);
 165                         goto Release_Fid;
 166                 }
 167
 168                 err = v9fs_t_walk(v9ses, base_fid->fid, fid, NULL, &fcall);
 169                 if (err < 0) {
 170                         dprintk(DEBUG_ERROR, "clone walk didn't work\n");
 171                         v9fs_put_idpool(fid, &v9ses->fidpool);
 172                         new_fid = ERR_PTR(err);
 173                         goto Free_Fcall;
 174                 }
 175                 new_fid = v9fs_fid_create(v9ses, fid);
 176                 if (new_fid == NULL) {
 177                         dprintk(DEBUG_ERROR, "out of memory\n");
 178                         new_fid = ERR_PTR(-ENOMEM);
 179                 }
 180 Free_Fcall:
 181                 kfree(fcall);
 182         }
 183
 184 Release_Fid:
 185         up(&base_fid->lock);
 186         return new_fid;
 187 }
 188
 189 void v9fs_fid_clunk(struct v9fs_session_info *v9ses, struct v9fs_fid *fid)
 190 {
 191         v9fs_t_clunk(v9ses, fid->fid);
 192         v9fs_fid_destroy(fid);
 193 }