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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
44static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid)
45{
46 hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata);
47}
48
49void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
50{
51 spin_lock(&dentry->d_lock);
52 __add_fid(dentry, fid);
53 spin_unlock(&dentry->d_lock);
54}
55
56/**
57 * v9fs_fid_find - retrieve a fid that belongs to the specified uid
58 * @dentry: dentry to look for fid in
59 * @uid: return fid that belongs to the specified user
60 * @any: if non-zero, return any fid associated with the dentry
61 *
62 */
63
64static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
65{
66 struct p9_fid *fid, *ret;
67
68 p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p) uid %d any %d\n",
69 dentry, dentry, from_kuid(&init_user_ns, uid),
70 any);
71 ret = NULL;
72 /* we'll recheck under lock if there's anything to look in */
73 if (dentry->d_fsdata) {
74 struct hlist_head *h = (struct hlist_head *)&dentry->d_fsdata;
75 spin_lock(&dentry->d_lock);
76 hlist_for_each_entry(fid, h, dlist) {
77 if (any || uid_eq(fid->uid, uid)) {
78 ret = fid;
79 break;
80 }
81 }
82 spin_unlock(&dentry->d_lock);
83 }
84
85 return ret;
86}
87
88/*
89 * We need to hold v9ses->rename_sem as long as we hold references
90 * to returned path array. Array element contain pointers to
91 * dentry names.
92 */
93static int build_path_from_dentry(struct v9fs_session_info *v9ses,
94 struct dentry *dentry, const unsigned char ***names)
95{
96 int n = 0, i;
97 const unsigned char **wnames;
98 struct dentry *ds;
99
100 for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent)
101 n++;
102
103 wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL);
104 if (!wnames)
105 goto err_out;
106
107 for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent)
108 wnames[i] = ds->d_name.name;
109
110 *names = wnames;
111 return n;
112err_out:
113 return -ENOMEM;
114}
115
116static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
117 kuid_t uid, int any)
118{
119 struct dentry *ds;
120 const unsigned char **wnames, *uname;
121 int i, n, l, clone, access;
122 struct v9fs_session_info *v9ses;
123 struct p9_fid *fid, *old_fid = NULL;
124
125 v9ses = v9fs_dentry2v9ses(dentry);
126 access = v9ses->flags & V9FS_ACCESS_MASK;
127 fid = v9fs_fid_find(dentry, uid, any);
128 if (fid)
129 return fid;
130 /*
131 * we don't have a matching fid. To do a TWALK we need
132 * parent fid. We need to prevent rename when we want to
133 * look at the parent.
134 */
135 down_read(&v9ses->rename_sem);
136 ds = dentry->d_parent;
137 fid = v9fs_fid_find(ds, uid, any);
138 if (fid) {
139 /* Found the parent fid do a lookup with that */
140 fid = p9_client_walk(fid, 1, &dentry->d_name.name, 1);
141 goto fid_out;
142 }
143 up_read(&v9ses->rename_sem);
144
145 /* start from the root and try to do a lookup */
146 fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any);
147 if (!fid) {
148 /* the user is not attached to the fs yet */
149 if (access == V9FS_ACCESS_SINGLE)
150 return ERR_PTR(-EPERM);
151
152 if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses))
153 uname = NULL;
154 else
155 uname = v9ses->uname;
156
157 fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
158 v9ses->aname);
159 if (IS_ERR(fid))
160 return fid;
161
162 v9fs_fid_add(dentry->d_sb->s_root, fid);
163 }
164 /* If we are root ourself just return that */
165 if (dentry->d_sb->s_root == dentry)
166 return fid;
167 /*
168 * Do a multipath walk with attached root.
169 * When walking parent we need to make sure we
170 * don't have a parallel rename happening
171 */
172 down_read(&v9ses->rename_sem);
173 n = build_path_from_dentry(v9ses, dentry, &wnames);
174 if (n < 0) {
175 fid = ERR_PTR(n);
176 goto err_out;
177 }
178 clone = 1;
179 i = 0;
180 while (i < n) {
181 l = min(n - i, P9_MAXWELEM);
182 /*
183 * We need to hold rename lock when doing a multipath
184 * walk to ensure none of the patch component change
185 */
186 fid = p9_client_walk(fid, l, &wnames[i], clone);
187 if (IS_ERR(fid)) {
188 if (old_fid) {
189 /*
190 * If we fail, clunk fid which are mapping
191 * to path component and not the last component
192 * of the path.
193 */
194 p9_client_clunk(old_fid);
195 }
196 kfree(wnames);
197 goto err_out;
198 }
199 old_fid = fid;
200 i += l;
201 clone = 0;
202 }
203 kfree(wnames);
204fid_out:
205 if (!IS_ERR(fid)) {
206 spin_lock(&dentry->d_lock);
207 if (d_unhashed(dentry)) {
208 spin_unlock(&dentry->d_lock);
209 p9_client_clunk(fid);
210 fid = ERR_PTR(-ENOENT);
211 } else {
212 __add_fid(dentry, fid);
213 spin_unlock(&dentry->d_lock);
214 }
215 }
216err_out:
217 up_read(&v9ses->rename_sem);
218 return fid;
219}
220
221/**
222 * v9fs_fid_lookup - lookup for a fid, try to walk if not found
223 * @dentry: dentry to look for fid in
224 *
225 * Look for a fid in the specified dentry for the current user.
226 * If no fid is found, try to create one walking from a fid from the parent
227 * dentry (if it has one), or the root dentry. If the user haven't accessed
228 * the fs yet, attach now and walk from the root.
229 */
230
231struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
232{
233 kuid_t uid;
234 int any, access;
235 struct v9fs_session_info *v9ses;
236
237 v9ses = v9fs_dentry2v9ses(dentry);
238 access = v9ses->flags & V9FS_ACCESS_MASK;
239 switch (access) {
240 case V9FS_ACCESS_SINGLE:
241 case V9FS_ACCESS_USER:
242 case V9FS_ACCESS_CLIENT:
243 uid = current_fsuid();
244 any = 0;
245 break;
246
247 case V9FS_ACCESS_ANY:
248 uid = v9ses->uid;
249 any = 1;
250 break;
251
252 default:
253 uid = INVALID_UID;
254 any = 0;
255 break;
256 }
257 return v9fs_fid_lookup_with_uid(dentry, uid, any);
258}
259
260struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
261{
262 int err;
263 struct p9_fid *fid;
264
265 fid = clone_fid(v9fs_fid_lookup_with_uid(dentry, GLOBAL_ROOT_UID, 0));
266 if (IS_ERR(fid))
267 goto error_out;
268 /*
269 * writeback fid will only be used to write back the
270 * dirty pages. We always request for the open fid in read-write
271 * mode so that a partial page write which result in page
272 * read can work.
273 */
274 err = p9_client_open(fid, O_RDWR);
275 if (err < 0) {
276 p9_client_clunk(fid);
277 fid = ERR_PTR(err);
278 goto error_out;
279 }
280error_out:
281 return fid;
282}
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
44static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid)
45{
46 hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata);
47}
48
49void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
50{
51 spin_lock(&dentry->d_lock);
52 __add_fid(dentry, fid);
53 spin_unlock(&dentry->d_lock);
54}
55
56/**
57 * v9fs_fid_find - retrieve a fid that belongs to the specified uid
58 * @dentry: dentry to look for fid in
59 * @uid: return fid that belongs to the specified user
60 * @any: if non-zero, return any fid associated with the dentry
61 *
62 */
63
64static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
65{
66 struct p9_fid *fid, *ret;
67
68 p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p) uid %d any %d\n",
69 dentry, dentry, from_kuid(&init_user_ns, uid),
70 any);
71 ret = NULL;
72 /* we'll recheck under lock if there's anything to look in */
73 if (dentry->d_fsdata) {
74 struct hlist_head *h = (struct hlist_head *)&dentry->d_fsdata;
75 spin_lock(&dentry->d_lock);
76 hlist_for_each_entry(fid, h, dlist) {
77 if (any || uid_eq(fid->uid, uid)) {
78 ret = fid;
79 break;
80 }
81 }
82 spin_unlock(&dentry->d_lock);
83 }
84
85 return ret;
86}
87
88/*
89 * We need to hold v9ses->rename_sem as long as we hold references
90 * to returned path array. Array element contain pointers to
91 * dentry names.
92 */
93static int build_path_from_dentry(struct v9fs_session_info *v9ses,
94 struct dentry *dentry, char ***names)
95{
96 int n = 0, i;
97 char **wnames;
98 struct dentry *ds;
99
100 for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent)
101 n++;
102
103 wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL);
104 if (!wnames)
105 goto err_out;
106
107 for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent)
108 wnames[i] = (char *)ds->d_name.name;
109
110 *names = wnames;
111 return n;
112err_out:
113 return -ENOMEM;
114}
115
116static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
117 kuid_t uid, int any)
118{
119 struct dentry *ds;
120 char **wnames, *uname;
121 int i, n, l, clone, access;
122 struct v9fs_session_info *v9ses;
123 struct p9_fid *fid, *old_fid = NULL;
124
125 v9ses = v9fs_dentry2v9ses(dentry);
126 access = v9ses->flags & V9FS_ACCESS_MASK;
127 fid = v9fs_fid_find(dentry, uid, any);
128 if (fid)
129 return fid;
130 /*
131 * we don't have a matching fid. To do a TWALK we need
132 * parent fid. We need to prevent rename when we want to
133 * look at the parent.
134 */
135 down_read(&v9ses->rename_sem);
136 ds = dentry->d_parent;
137 fid = v9fs_fid_find(ds, uid, any);
138 if (fid) {
139 /* Found the parent fid do a lookup with that */
140 fid = p9_client_walk(fid, 1, (char **)&dentry->d_name.name, 1);
141 goto fid_out;
142 }
143 up_read(&v9ses->rename_sem);
144
145 /* start from the root and try to do a lookup */
146 fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any);
147 if (!fid) {
148 /* the user is not attached to the fs yet */
149 if (access == V9FS_ACCESS_SINGLE)
150 return ERR_PTR(-EPERM);
151
152 if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses))
153 uname = NULL;
154 else
155 uname = v9ses->uname;
156
157 fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
158 v9ses->aname);
159 if (IS_ERR(fid))
160 return fid;
161
162 v9fs_fid_add(dentry->d_sb->s_root, fid);
163 }
164 /* If we are root ourself just return that */
165 if (dentry->d_sb->s_root == dentry)
166 return fid;
167 /*
168 * Do a multipath walk with attached root.
169 * When walking parent we need to make sure we
170 * don't have a parallel rename happening
171 */
172 down_read(&v9ses->rename_sem);
173 n = build_path_from_dentry(v9ses, dentry, &wnames);
174 if (n < 0) {
175 fid = ERR_PTR(n);
176 goto err_out;
177 }
178 clone = 1;
179 i = 0;
180 while (i < n) {
181 l = min(n - i, P9_MAXWELEM);
182 /*
183 * We need to hold rename lock when doing a multipath
184 * walk to ensure none of the patch component change
185 */
186 fid = p9_client_walk(fid, l, &wnames[i], clone);
187 if (IS_ERR(fid)) {
188 if (old_fid) {
189 /*
190 * If we fail, clunk fid which are mapping
191 * to path component and not the last component
192 * of the path.
193 */
194 p9_client_clunk(old_fid);
195 }
196 kfree(wnames);
197 goto err_out;
198 }
199 old_fid = fid;
200 i += l;
201 clone = 0;
202 }
203 kfree(wnames);
204fid_out:
205 if (!IS_ERR(fid)) {
206 spin_lock(&dentry->d_lock);
207 if (d_unhashed(dentry)) {
208 spin_unlock(&dentry->d_lock);
209 p9_client_clunk(fid);
210 fid = ERR_PTR(-ENOENT);
211 } else {
212 __add_fid(dentry, fid);
213 spin_unlock(&dentry->d_lock);
214 }
215 }
216err_out:
217 up_read(&v9ses->rename_sem);
218 return fid;
219}
220
221/**
222 * v9fs_fid_lookup - lookup for a fid, try to walk if not found
223 * @dentry: dentry to look for fid in
224 *
225 * Look for a fid in the specified dentry for the current user.
226 * If no fid is found, try to create one walking from a fid from the parent
227 * dentry (if it has one), or the root dentry. If the user haven't accessed
228 * the fs yet, attach now and walk from the root.
229 */
230
231struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
232{
233 kuid_t uid;
234 int any, access;
235 struct v9fs_session_info *v9ses;
236
237 v9ses = v9fs_dentry2v9ses(dentry);
238 access = v9ses->flags & V9FS_ACCESS_MASK;
239 switch (access) {
240 case V9FS_ACCESS_SINGLE:
241 case V9FS_ACCESS_USER:
242 case V9FS_ACCESS_CLIENT:
243 uid = current_fsuid();
244 any = 0;
245 break;
246
247 case V9FS_ACCESS_ANY:
248 uid = v9ses->uid;
249 any = 1;
250 break;
251
252 default:
253 uid = INVALID_UID;
254 any = 0;
255 break;
256 }
257 return v9fs_fid_lookup_with_uid(dentry, uid, any);
258}
259
260struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
261{
262 int err;
263 struct p9_fid *fid;
264
265 fid = clone_fid(v9fs_fid_lookup_with_uid(dentry, GLOBAL_ROOT_UID, 0));
266 if (IS_ERR(fid))
267 goto error_out;
268 /*
269 * writeback fid will only be used to write back the
270 * dirty pages. We always request for the open fid in read-write
271 * mode so that a partial page write which result in page
272 * read can work.
273 */
274 err = p9_client_open(fid, O_RDWR);
275 if (err < 0) {
276 p9_client_clunk(fid);
277 fid = ERR_PTR(err);
278 goto error_out;
279 }
280error_out:
281 return fid;
282}