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-rw-r--r--fs/9p/fid.c241
1 files changed, 241 insertions, 0 deletions
diff --git a/fs/9p/fid.c b/fs/9p/fid.c
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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
46static 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
74struct 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
105void 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
122struct 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}
generated by cgit v1.2.2 (git 2.25.0) at 2025-11-10 04:15:28 -0500