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 #include <net/9p/9p.h>
  30 #include <net/9p/client.h>
  31
  32 #include "v9fs.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_add(struct dentry *dentry, struct p9_fid *fid)
  44 {
  45         struct v9fs_dentry *dent;
  46
  47         P9_DPRINTK(P9_DEBUG_VFS, "fid %d dentry %s\n",
  48                                         fid->fid, dentry->d_iname);
  49
  50         dent = dentry->d_fsdata;
  51         if (!dent) {
  52                 dent = kmalloc(sizeof(struct v9fs_dentry), GFP_KERNEL);
  53                 if (!dent)
  54                         return -ENOMEM;
  55
  56                 spin_lock_init(&dent->lock);
  57                 INIT_LIST_HEAD(&dent->fidlist);
  58                 dentry->d_fsdata = dent;
  59         }
  60
  61         spin_lock(&dent->lock);
  62         list_add(&fid->dlist, &dent->fidlist);
  63         spin_unlock(&dent->lock);
  64
  65         return 0;
  66 }
  67
  68 /**
  69  * v9fs_fid_lookup - return a locked fid from a dentry
  70  * @dentry: dentry to look for fid in
  71  *
  72  * find a fid in the dentry, obtain its semaphore and return a reference to it.
  73  * code calling lookup is responsible for releasing lock
  74  *
  75  * TODO: only match fids that have the same uid as current user
  76  *
  77  */
  78
  79 struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
  80 {
  81         struct v9fs_dentry *dent;
  82         struct p9_fid *fid;
  83
  84         P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p)\n", dentry->d_iname, dentry);
  85         dent = dentry->d_fsdata;
  86         if (dent)
  87                 fid = list_entry(dent->fidlist.next, struct p9_fid, dlist);
  88         else
  89                 fid = ERR_PTR(-EBADF);
  90
  91         P9_DPRINTK(P9_DEBUG_VFS, " fid: %p\n", fid);
  92         return fid;
  93 }
  94
  95 struct p9_fid *v9fs_fid_lookup_remove(struct dentry *dentry)
  96 {
  97         struct p9_fid *fid;
  98         struct v9fs_dentry *dent;
  99
 100         dent = dentry->d_fsdata;
 101         fid = v9fs_fid_lookup(dentry);
 102         if (!IS_ERR(fid)) {
 103                 spin_lock(&dent->lock);
 104                 list_del(&fid->dlist);
 105                 spin_unlock(&dent->lock);
 106         }
 107
 108         return fid;
 109 }
 110
 111
 112 /**
 113  * v9fs_fid_clone - lookup the fid for a dentry, clone a private copy and
 114  *      release it
 115  * @dentry: dentry to look for fid in
 116  *
 117  * find a fid in the dentry and then clone to a new private fid
 118  *
 119  * TODO: only match fids that have the same uid as current user
 120  *
 121  */
 122
 123 struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
 124 {
 125         struct p9_fid *ofid, *fid;
 126
 127         P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p)\n", dentry->d_iname, dentry);
 128         ofid = v9fs_fid_lookup(dentry);
 129         if (IS_ERR(ofid))
 130                 return ofid;
 131
 132         fid = p9_client_walk(ofid, 0, NULL, 1);
 133         return fid;
 134 }