821c9c4d76aa064698025e4c5444894b7dc8e39f
[linux-2.6.git] / 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 }