[PATCH] v9fs: new multiplexer implementation
[linux-3.10.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         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);
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 }