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Eric Van Hensbergen3ed84912005-09-09 13:04:24 -07001/*
2 * V9FS FID Management
3 *
Latchesar Ionkovba176742007-10-17 14:31:07 -05004 * Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
Eric Van Hensbergen46f6dac2006-03-02 02:54:33 -08005 * Copyright (C) 2005, 2006 by Eric Van Hensbergen <ericvh@gmail.com>
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -07006 *
7 * This program is free software; you can redistribute it and/or modify
Eric Van Hensbergen42e8c502006-03-25 03:07:28 -08008 * it under the terms of the GNU General Public License version 2
9 * as published by the Free Software Foundation.
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070010 *
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
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070024#include <linux/module.h>
25#include <linux/errno.h>
26#include <linux/fs.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090027#include <linux/slab.h>
Al Viro914e2632006-10-18 13:55:46 -040028#include <linux/sched.h>
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070029#include <linux/idr.h>
Latchesar Ionkovbd238fb2007-07-10 17:57:28 -050030#include <net/9p/9p.h>
31#include <net/9p/client.h>
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070032
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070033#include "v9fs.h"
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070034#include "v9fs_vfs.h"
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070035#include "fid.h"
36
37/**
Latchesar Ionkovba176742007-10-17 14:31:07 -050038 * v9fs_fid_add - add a fid to a dentry
39 * @dentry: dentry that the fid is being added to
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070040 * @fid: fid to add
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070041 *
42 */
43
Al Viro5e608672013-02-28 01:50:20 -050044static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid)
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070045{
Al Viro5e608672013-02-28 01:50:20 -050046 hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata);
47}
Latchesar Ionkovbd238fb2007-07-10 17:57:28 -050048
Al Viro2ea03e1d2013-02-28 01:18:14 -050049void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070050{
Al Viro634095d2013-02-27 22:37:21 -050051 spin_lock(&dentry->d_lock);
Al Viro5e608672013-02-28 01:50:20 -050052 __add_fid(dentry, fid);
Al Viro634095d2013-02-27 22:37:21 -050053 spin_unlock(&dentry->d_lock);
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070054}
55
56/**
Latchesar Ionkovba176742007-10-17 14:31:07 -050057 * 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
Eric W. Biedermanb4642552013-01-30 11:48:53 -080064static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
Latchesar Ionkovba176742007-10-17 14:31:07 -050065{
Latchesar Ionkovba176742007-10-17 14:31:07 -050066 struct p9_fid *fid, *ret;
67
Al Viro4b8e9922014-08-19 20:17:38 -040068 p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p) uid %d any %d\n",
69 dentry, dentry, from_kuid(&init_user_ns, uid),
Eric W. Biedermanb4642552013-01-30 11:48:53 -080070 any);
Latchesar Ionkovba176742007-10-17 14:31:07 -050071 ret = NULL;
Al Viroaaeb7ec2013-02-28 01:13:19 -050072 /* 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;
Al Viro634095d2013-02-27 22:37:21 -050075 spin_lock(&dentry->d_lock);
Linus Torvalds56a79b72013-03-03 13:23:02 -080076 hlist_for_each_entry(fid, h, dlist) {
Eric W. Biedermanb4642552013-01-30 11:48:53 -080077 if (any || uid_eq(fid->uid, uid)) {
Latchesar Ionkovba176742007-10-17 14:31:07 -050078 ret = fid;
79 break;
80 }
81 }
Al Viro634095d2013-02-27 22:37:21 -050082 spin_unlock(&dentry->d_lock);
Latchesar Ionkovba176742007-10-17 14:31:07 -050083 }
84
85 return ret;
86}
87
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +053088/*
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
Aneesh Kumar K.V7c9e5922011-02-28 17:04:11 +0530116static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
Eric W. Biedermanb4642552013-01-30 11:48:53 -0800117 kuid_t uid, int any)
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -0700118{
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530119 struct dentry *ds;
Latchesar Ionkovba176742007-10-17 14:31:07 -0500120 char **wnames, *uname;
Aneesh Kumar K.V7c9e5922011-02-28 17:04:11 +0530121 int i, n, l, clone, access;
122 struct v9fs_session_info *v9ses;
123 struct p9_fid *fid, *old_fid = NULL;
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -0700124
Aneesh Kumar K.V42869c82011-03-08 16:39:50 +0530125 v9ses = v9fs_dentry2v9ses(dentry);
Latchesar Ionkovba176742007-10-17 14:31:07 -0500126 access = v9ses->flags & V9FS_ACCESS_MASK;
Latchesar Ionkovba176742007-10-17 14:31:07 -0500127 fid = v9fs_fid_find(dentry, uid, any);
128 if (fid)
129 return fid;
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530130 /*
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);
Latchesar Ionkovba176742007-10-17 14:31:07 -0500136 ds = dentry->d_parent;
137 fid = v9fs_fid_find(ds, uid, any);
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530138 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);
Latchesar Ionkovba176742007-10-17 14:31:07 -0500144
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530145 /* 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);
Latchesar Ionkovba176742007-10-17 14:31:07 -0500151
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530152 if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses))
Latchesar Ionkovba176742007-10-17 14:31:07 -0500153 uname = NULL;
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530154 else
155 uname = v9ses->uname;
Latchesar Ionkovba176742007-10-17 14:31:07 -0500156
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530157 fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
158 v9ses->aname);
159 if (IS_ERR(fid))
160 return fid;
Latchesar Ionkovba176742007-10-17 14:31:07 -0500161
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530162 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)
Latchesar Ionkovba176742007-10-17 14:31:07 -0500166 return fid;
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530167 /*
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 }
Latchesar Ionkovba176742007-10-17 14:31:07 -0500178 clone = 1;
179 i = 0;
180 while (i < n) {
181 l = min(n - i, P9_MAXWELEM);
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530182 /*
183 * We need to hold rename lock when doing a multipath
184 * walk to ensure none of the patch component change
185 */
Latchesar Ionkovba176742007-10-17 14:31:07 -0500186 fid = p9_client_walk(fid, l, &wnames[i], clone);
Eric Van Hensbergenc55703d2008-02-06 19:25:08 -0600187 if (IS_ERR(fid)) {
Aneesh Kumar K.V5b0fa202010-03-19 12:47:26 +0000188 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 }
Latchesar Ionkovba176742007-10-17 14:31:07 -0500196 kfree(wnames);
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530197 goto err_out;
Latchesar Ionkovba176742007-10-17 14:31:07 -0500198 }
Aneesh Kumar K.V5b0fa202010-03-19 12:47:26 +0000199 old_fid = fid;
Latchesar Ionkovba176742007-10-17 14:31:07 -0500200 i += l;
201 clone = 0;
202 }
Latchesar Ionkovba176742007-10-17 14:31:07 -0500203 kfree(wnames);
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530204fid_out:
Al Viro5e608672013-02-28 01:50:20 -0500205 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 }
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530216err_out:
217 up_read(&v9ses->rename_sem);
Latchesar Ionkovbd238fb2007-07-10 17:57:28 -0500218 return fid;
219}
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -0700220
Aneesh Kumar K.V7c9e5922011-02-28 17:04:11 +0530221/**
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{
Eric W. Biedermanb4642552013-01-30 11:48:53 -0800233 kuid_t uid;
Aneesh Kumar K.V7c9e5922011-02-28 17:04:11 +0530234 int any, access;
235 struct v9fs_session_info *v9ses;
236
Aneesh Kumar K.V42869c82011-03-08 16:39:50 +0530237 v9ses = v9fs_dentry2v9ses(dentry);
Aneesh Kumar K.V7c9e5922011-02-28 17:04:11 +0530238 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:
Eric W. Biedermanb4642552013-01-30 11:48:53 -0800253 uid = INVALID_UID;
Aneesh Kumar K.V7c9e5922011-02-28 17:04:11 +0530254 any = 0;
255 break;
256 }
257 return v9fs_fid_lookup_with_uid(dentry, uid, any);
258}
259
Latchesar Ionkovbd238fb2007-07-10 17:57:28 -0500260struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
Eric Van Hensbergenda977b22007-01-26 00:57:06 -0800261{
Latchesar Ionkovba176742007-10-17 14:31:07 -0500262 struct p9_fid *fid, *ret;
Eric Van Hensbergenda977b22007-01-26 00:57:06 -0800263
Latchesar Ionkovba176742007-10-17 14:31:07 -0500264 fid = v9fs_fid_lookup(dentry);
265 if (IS_ERR(fid))
266 return fid;
Eric Van Hensbergenda977b22007-01-26 00:57:06 -0800267
Latchesar Ionkovba176742007-10-17 14:31:07 -0500268 ret = p9_client_walk(fid, 0, NULL, 1);
269 return ret;
Eric Van Hensbergenda977b22007-01-26 00:57:06 -0800270}
Aneesh Kumar K.V3cf387d2011-02-28 17:03:57 +0530271
Eric W. Biedermanb4642552013-01-30 11:48:53 -0800272static struct p9_fid *v9fs_fid_clone_with_uid(struct dentry *dentry, kuid_t uid)
Aneesh Kumar K.V7c9e5922011-02-28 17:04:11 +0530273{
274 struct p9_fid *fid, *ret;
275
276 fid = v9fs_fid_lookup_with_uid(dentry, uid, 0);
277 if (IS_ERR(fid))
278 return fid;
279
280 ret = p9_client_walk(fid, 0, NULL, 1);
281 return ret;
282}
Aneesh Kumar K.V3cf387d2011-02-28 17:03:57 +0530283
284struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
285{
Aneesh Kumar K.Vdf5d8c82011-03-24 20:38:35 +0530286 int err;
Aneesh Kumar K.V3cf387d2011-02-28 17:03:57 +0530287 struct p9_fid *fid;
288
Eric W. Biedermanb4642552013-01-30 11:48:53 -0800289 fid = v9fs_fid_clone_with_uid(dentry, GLOBAL_ROOT_UID);
Aneesh Kumar K.V3cf387d2011-02-28 17:03:57 +0530290 if (IS_ERR(fid))
291 goto error_out;
292 /*
293 * writeback fid will only be used to write back the
294 * dirty pages. We always request for the open fid in read-write
295 * mode so that a partial page write which result in page
296 * read can work.
Aneesh Kumar K.V3cf387d2011-02-28 17:03:57 +0530297 */
Aneesh Kumar K.Vdf5d8c82011-03-24 20:38:35 +0530298 err = p9_client_open(fid, O_RDWR);
Aneesh Kumar K.V3cf387d2011-02-28 17:03:57 +0530299 if (err < 0) {
300 p9_client_clunk(fid);
301 fid = ERR_PTR(err);
302 goto error_out;
303 }
304error_out:
305 return fid;
306}