Loading...
1/*
2 * V9FS FID Management
3 *
4 * Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
5 * Copyright (C) 2005, 2006 by Eric Van Hensbergen <ericvh@gmail.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2
9 * as published by the Free Software Foundation.
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/module.h>
25#include <linux/errno.h>
26#include <linux/fs.h>
27#include <linux/slab.h>
28#include <linux/sched.h>
29#include <linux/idr.h>
30#include <net/9p/9p.h>
31#include <net/9p/client.h>
32
33#include "v9fs.h"
34#include "v9fs_vfs.h"
35#include "fid.h"
36
37/**
38 * v9fs_fid_add - add a fid to a dentry
39 * @dentry: dentry that the fid is being added to
40 * @fid: fid to add
41 *
42 */
43
44int v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
45{
46 struct v9fs_dentry *dent;
47
48 p9_debug(P9_DEBUG_VFS, "fid %d dentry %s\n",
49 fid->fid, dentry->d_name.name);
50
51 dent = dentry->d_fsdata;
52 if (!dent) {
53 dent = kmalloc(sizeof(struct v9fs_dentry), GFP_KERNEL);
54 if (!dent)
55 return -ENOMEM;
56
57 spin_lock_init(&dent->lock);
58 INIT_LIST_HEAD(&dent->fidlist);
59 dentry->d_fsdata = dent;
60 }
61
62 spin_lock(&dent->lock);
63 list_add(&fid->dlist, &dent->fidlist);
64 spin_unlock(&dent->lock);
65
66 return 0;
67}
68
69/**
70 * v9fs_fid_find - retrieve a fid that belongs to the specified uid
71 * @dentry: dentry to look for fid in
72 * @uid: return fid that belongs to the specified user
73 * @any: if non-zero, return any fid associated with the dentry
74 *
75 */
76
77static struct p9_fid *v9fs_fid_find(struct dentry *dentry, u32 uid, int any)
78{
79 struct v9fs_dentry *dent;
80 struct p9_fid *fid, *ret;
81
82 p9_debug(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n",
83 dentry->d_name.name, dentry, uid, any);
84 dent = (struct v9fs_dentry *) dentry->d_fsdata;
85 ret = NULL;
86 if (dent) {
87 spin_lock(&dent->lock);
88 list_for_each_entry(fid, &dent->fidlist, dlist) {
89 if (any || fid->uid == uid) {
90 ret = fid;
91 break;
92 }
93 }
94 spin_unlock(&dent->lock);
95 }
96
97 return ret;
98}
99
100/*
101 * We need to hold v9ses->rename_sem as long as we hold references
102 * to returned path array. Array element contain pointers to
103 * dentry names.
104 */
105static int build_path_from_dentry(struct v9fs_session_info *v9ses,
106 struct dentry *dentry, char ***names)
107{
108 int n = 0, i;
109 char **wnames;
110 struct dentry *ds;
111
112 for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent)
113 n++;
114
115 wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL);
116 if (!wnames)
117 goto err_out;
118
119 for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent)
120 wnames[i] = (char *)ds->d_name.name;
121
122 *names = wnames;
123 return n;
124err_out:
125 return -ENOMEM;
126}
127
128static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
129 uid_t uid, int any)
130{
131 struct dentry *ds;
132 char **wnames, *uname;
133 int i, n, l, clone, access;
134 struct v9fs_session_info *v9ses;
135 struct p9_fid *fid, *old_fid = NULL;
136
137 v9ses = v9fs_dentry2v9ses(dentry);
138 access = v9ses->flags & V9FS_ACCESS_MASK;
139 fid = v9fs_fid_find(dentry, uid, any);
140 if (fid)
141 return fid;
142 /*
143 * we don't have a matching fid. To do a TWALK we need
144 * parent fid. We need to prevent rename when we want to
145 * look at the parent.
146 */
147 down_read(&v9ses->rename_sem);
148 ds = dentry->d_parent;
149 fid = v9fs_fid_find(ds, uid, any);
150 if (fid) {
151 /* Found the parent fid do a lookup with that */
152 fid = p9_client_walk(fid, 1, (char **)&dentry->d_name.name, 1);
153 goto fid_out;
154 }
155 up_read(&v9ses->rename_sem);
156
157 /* start from the root and try to do a lookup */
158 fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any);
159 if (!fid) {
160 /* the user is not attached to the fs yet */
161 if (access == V9FS_ACCESS_SINGLE)
162 return ERR_PTR(-EPERM);
163
164 if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses))
165 uname = NULL;
166 else
167 uname = v9ses->uname;
168
169 fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
170 v9ses->aname);
171 if (IS_ERR(fid))
172 return fid;
173
174 v9fs_fid_add(dentry->d_sb->s_root, fid);
175 }
176 /* If we are root ourself just return that */
177 if (dentry->d_sb->s_root == dentry)
178 return fid;
179 /*
180 * Do a multipath walk with attached root.
181 * When walking parent we need to make sure we
182 * don't have a parallel rename happening
183 */
184 down_read(&v9ses->rename_sem);
185 n = build_path_from_dentry(v9ses, dentry, &wnames);
186 if (n < 0) {
187 fid = ERR_PTR(n);
188 goto err_out;
189 }
190 clone = 1;
191 i = 0;
192 while (i < n) {
193 l = min(n - i, P9_MAXWELEM);
194 /*
195 * We need to hold rename lock when doing a multipath
196 * walk to ensure none of the patch component change
197 */
198 fid = p9_client_walk(fid, l, &wnames[i], clone);
199 if (IS_ERR(fid)) {
200 if (old_fid) {
201 /*
202 * If we fail, clunk fid which are mapping
203 * to path component and not the last component
204 * of the path.
205 */
206 p9_client_clunk(old_fid);
207 }
208 kfree(wnames);
209 goto err_out;
210 }
211 old_fid = fid;
212 i += l;
213 clone = 0;
214 }
215 kfree(wnames);
216fid_out:
217 if (!IS_ERR(fid))
218 v9fs_fid_add(dentry, fid);
219err_out:
220 up_read(&v9ses->rename_sem);
221 return fid;
222}
223
224/**
225 * v9fs_fid_lookup - lookup for a fid, try to walk if not found
226 * @dentry: dentry to look for fid in
227 *
228 * Look for a fid in the specified dentry for the current user.
229 * If no fid is found, try to create one walking from a fid from the parent
230 * dentry (if it has one), or the root dentry. If the user haven't accessed
231 * the fs yet, attach now and walk from the root.
232 */
233
234struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
235{
236 uid_t uid;
237 int any, access;
238 struct v9fs_session_info *v9ses;
239
240 v9ses = v9fs_dentry2v9ses(dentry);
241 access = v9ses->flags & V9FS_ACCESS_MASK;
242 switch (access) {
243 case V9FS_ACCESS_SINGLE:
244 case V9FS_ACCESS_USER:
245 case V9FS_ACCESS_CLIENT:
246 uid = current_fsuid();
247 any = 0;
248 break;
249
250 case V9FS_ACCESS_ANY:
251 uid = v9ses->uid;
252 any = 1;
253 break;
254
255 default:
256 uid = ~0;
257 any = 0;
258 break;
259 }
260 return v9fs_fid_lookup_with_uid(dentry, uid, any);
261}
262
263struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
264{
265 struct p9_fid *fid, *ret;
266
267 fid = v9fs_fid_lookup(dentry);
268 if (IS_ERR(fid))
269 return fid;
270
271 ret = p9_client_walk(fid, 0, NULL, 1);
272 return ret;
273}
274
275static struct p9_fid *v9fs_fid_clone_with_uid(struct dentry *dentry, uid_t uid)
276{
277 struct p9_fid *fid, *ret;
278
279 fid = v9fs_fid_lookup_with_uid(dentry, uid, 0);
280 if (IS_ERR(fid))
281 return fid;
282
283 ret = p9_client_walk(fid, 0, NULL, 1);
284 return ret;
285}
286
287struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
288{
289 int err;
290 struct p9_fid *fid;
291
292 fid = v9fs_fid_clone_with_uid(dentry, 0);
293 if (IS_ERR(fid))
294 goto error_out;
295 /*
296 * writeback fid will only be used to write back the
297 * dirty pages. We always request for the open fid in read-write
298 * mode so that a partial page write which result in page
299 * read can work.
300 */
301 err = p9_client_open(fid, O_RDWR);
302 if (err < 0) {
303 p9_client_clunk(fid);
304 fid = ERR_PTR(err);
305 goto error_out;
306 }
307error_out:
308 return fid;
309}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * V9FS FID Management
4 *
5 * Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
6 * Copyright (C) 2005, 2006 by Eric Van Hensbergen <ericvh@gmail.com>
7 */
8
9#include <linux/module.h>
10#include <linux/errno.h>
11#include <linux/fs.h>
12#include <linux/slab.h>
13#include <linux/sched.h>
14#include <linux/idr.h>
15#include <net/9p/9p.h>
16#include <net/9p/client.h>
17
18#include "v9fs.h"
19#include "v9fs_vfs.h"
20#include "fid.h"
21
22/**
23 * v9fs_fid_add - add a fid to a dentry
24 * @dentry: dentry that the fid is being added to
25 * @fid: fid to add
26 *
27 */
28
29static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid)
30{
31 hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata);
32}
33
34void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
35{
36 spin_lock(&dentry->d_lock);
37 __add_fid(dentry, fid);
38 spin_unlock(&dentry->d_lock);
39}
40
41/**
42 * v9fs_fid_find_inode - search for an open fid off of the inode list
43 * @inode: return a fid pointing to a specific inode
44 * @uid: return a fid belonging to the specified user
45 *
46 */
47
48static struct p9_fid *v9fs_fid_find_inode(struct inode *inode, kuid_t uid)
49{
50 struct hlist_head *h;
51 struct p9_fid *fid, *ret = NULL;
52
53 p9_debug(P9_DEBUG_VFS, " inode: %p\n", inode);
54
55 spin_lock(&inode->i_lock);
56 h = (struct hlist_head *)&inode->i_private;
57 hlist_for_each_entry(fid, h, ilist) {
58 if (uid_eq(fid->uid, uid)) {
59 refcount_inc(&fid->count);
60 ret = fid;
61 break;
62 }
63 }
64 spin_unlock(&inode->i_lock);
65 return ret;
66}
67
68/**
69 * v9fs_open_fid_add - add an open fid to an inode
70 * @dentry: inode that the fid is being added to
71 * @fid: fid to add
72 *
73 */
74
75void v9fs_open_fid_add(struct inode *inode, struct p9_fid *fid)
76{
77 spin_lock(&inode->i_lock);
78 hlist_add_head(&fid->ilist, (struct hlist_head *)&inode->i_private);
79 spin_unlock(&inode->i_lock);
80}
81
82
83/**
84 * v9fs_fid_find - retrieve a fid that belongs to the specified uid
85 * @dentry: dentry to look for fid in
86 * @uid: return fid that belongs to the specified user
87 * @any: if non-zero, return any fid associated with the dentry
88 *
89 */
90
91static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
92{
93 struct p9_fid *fid, *ret;
94
95 p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p) uid %d any %d\n",
96 dentry, dentry, from_kuid(&init_user_ns, uid),
97 any);
98 ret = NULL;
99
100 if (d_inode(dentry))
101 ret = v9fs_fid_find_inode(d_inode(dentry), uid);
102
103 /* we'll recheck under lock if there's anything to look in */
104 if (!ret && dentry->d_fsdata) {
105 struct hlist_head *h = (struct hlist_head *)&dentry->d_fsdata;
106 spin_lock(&dentry->d_lock);
107 hlist_for_each_entry(fid, h, dlist) {
108 if (any || uid_eq(fid->uid, uid)) {
109 ret = fid;
110 refcount_inc(&ret->count);
111 break;
112 }
113 }
114 spin_unlock(&dentry->d_lock);
115 }
116
117 return ret;
118}
119
120/*
121 * We need to hold v9ses->rename_sem as long as we hold references
122 * to returned path array. Array element contain pointers to
123 * dentry names.
124 */
125static int build_path_from_dentry(struct v9fs_session_info *v9ses,
126 struct dentry *dentry, const unsigned char ***names)
127{
128 int n = 0, i;
129 const unsigned char **wnames;
130 struct dentry *ds;
131
132 for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent)
133 n++;
134
135 wnames = kmalloc_array(n, sizeof(char *), GFP_KERNEL);
136 if (!wnames)
137 goto err_out;
138
139 for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent)
140 wnames[i] = ds->d_name.name;
141
142 *names = wnames;
143 return n;
144err_out:
145 return -ENOMEM;
146}
147
148static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
149 kuid_t uid, int any)
150{
151 struct dentry *ds;
152 const unsigned char **wnames, *uname;
153 int i, n, l, clone, access;
154 struct v9fs_session_info *v9ses;
155 struct p9_fid *fid, *old_fid = NULL;
156
157 v9ses = v9fs_dentry2v9ses(dentry);
158 access = v9ses->flags & V9FS_ACCESS_MASK;
159 fid = v9fs_fid_find(dentry, uid, any);
160 if (fid)
161 return fid;
162 /*
163 * we don't have a matching fid. To do a TWALK we need
164 * parent fid. We need to prevent rename when we want to
165 * look at the parent.
166 */
167 down_read(&v9ses->rename_sem);
168 ds = dentry->d_parent;
169 fid = v9fs_fid_find(ds, uid, any);
170 if (fid) {
171 /* Found the parent fid do a lookup with that */
172 struct p9_fid *ofid = fid;
173
174 fid = p9_client_walk(ofid, 1, &dentry->d_name.name, 1);
175 p9_client_clunk(ofid);
176 goto fid_out;
177 }
178 up_read(&v9ses->rename_sem);
179
180 /* start from the root and try to do a lookup */
181 fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any);
182 if (!fid) {
183 /* the user is not attached to the fs yet */
184 if (access == V9FS_ACCESS_SINGLE)
185 return ERR_PTR(-EPERM);
186
187 if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses))
188 uname = NULL;
189 else
190 uname = v9ses->uname;
191
192 fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
193 v9ses->aname);
194 if (IS_ERR(fid))
195 return fid;
196
197 v9fs_fid_add(dentry->d_sb->s_root, fid);
198 }
199 /* If we are root ourself just return that */
200 if (dentry->d_sb->s_root == dentry) {
201 refcount_inc(&fid->count);
202 return fid;
203 }
204 /*
205 * Do a multipath walk with attached root.
206 * When walking parent we need to make sure we
207 * don't have a parallel rename happening
208 */
209 down_read(&v9ses->rename_sem);
210 n = build_path_from_dentry(v9ses, dentry, &wnames);
211 if (n < 0) {
212 fid = ERR_PTR(n);
213 goto err_out;
214 }
215 clone = 1;
216 i = 0;
217 while (i < n) {
218 l = min(n - i, P9_MAXWELEM);
219 /*
220 * We need to hold rename lock when doing a multipath
221 * walk to ensure none of the patch component change
222 */
223 fid = p9_client_walk(fid, l, &wnames[i], clone);
224 if (IS_ERR(fid)) {
225 if (old_fid) {
226 /*
227 * If we fail, clunk fid which are mapping
228 * to path component and not the last component
229 * of the path.
230 */
231 p9_client_clunk(old_fid);
232 }
233 kfree(wnames);
234 goto err_out;
235 }
236 old_fid = fid;
237 i += l;
238 clone = 0;
239 }
240 kfree(wnames);
241fid_out:
242 if (!IS_ERR(fid)) {
243 spin_lock(&dentry->d_lock);
244 if (d_unhashed(dentry)) {
245 spin_unlock(&dentry->d_lock);
246 p9_client_clunk(fid);
247 fid = ERR_PTR(-ENOENT);
248 } else {
249 __add_fid(dentry, fid);
250 refcount_inc(&fid->count);
251 spin_unlock(&dentry->d_lock);
252 }
253 }
254err_out:
255 up_read(&v9ses->rename_sem);
256 return fid;
257}
258
259/**
260 * v9fs_fid_lookup - lookup for a fid, try to walk if not found
261 * @dentry: dentry to look for fid in
262 *
263 * Look for a fid in the specified dentry for the current user.
264 * If no fid is found, try to create one walking from a fid from the parent
265 * dentry (if it has one), or the root dentry. If the user haven't accessed
266 * the fs yet, attach now and walk from the root.
267 */
268
269struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
270{
271 kuid_t uid;
272 int any, access;
273 struct v9fs_session_info *v9ses;
274
275 v9ses = v9fs_dentry2v9ses(dentry);
276 access = v9ses->flags & V9FS_ACCESS_MASK;
277 switch (access) {
278 case V9FS_ACCESS_SINGLE:
279 case V9FS_ACCESS_USER:
280 case V9FS_ACCESS_CLIENT:
281 uid = current_fsuid();
282 any = 0;
283 break;
284
285 case V9FS_ACCESS_ANY:
286 uid = v9ses->uid;
287 any = 1;
288 break;
289
290 default:
291 uid = INVALID_UID;
292 any = 0;
293 break;
294 }
295 return v9fs_fid_lookup_with_uid(dentry, uid, any);
296}
297
298struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
299{
300 int err;
301 struct p9_fid *fid, *ofid;
302
303 ofid = v9fs_fid_lookup_with_uid(dentry, GLOBAL_ROOT_UID, 0);
304 fid = clone_fid(ofid);
305 if (IS_ERR(fid))
306 goto error_out;
307 p9_client_clunk(ofid);
308 /*
309 * writeback fid will only be used to write back the
310 * dirty pages. We always request for the open fid in read-write
311 * mode so that a partial page write which result in page
312 * read can work.
313 */
314 err = p9_client_open(fid, O_RDWR);
315 if (err < 0) {
316 p9_client_clunk(fid);
317 fid = ERR_PTR(err);
318 goto error_out;
319 }
320error_out:
321 return fid;
322}