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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
Latchesar Ionkovbd238fb2007-07-10 17:57:28 -050044int v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070045{
Latchesar Ionkovbd238fb2007-07-10 17:57:28 -050046 struct v9fs_dentry *dent;
47
48 P9_DPRINTK(P9_DEBUG_VFS, "fid %d dentry %s\n",
Wu Fengguang7dd0cdc2008-12-19 16:47:40 -060049 fid->fid, dentry->d_name.name);
Latchesar Ionkovbd238fb2007-07-10 17:57:28 -050050
51 dent = dentry->d_fsdata;
52 if (!dent) {
53 dent = kmalloc(sizeof(struct v9fs_dentry), GFP_KERNEL);
54 if (!dent)
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070055 return -ENOMEM;
Latchesar Ionkovbd238fb2007-07-10 17:57:28 -050056
57 spin_lock_init(&dent->lock);
58 INIT_LIST_HEAD(&dent->fidlist);
59 dentry->d_fsdata = dent;
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070060 }
61
Latchesar Ionkovbd238fb2007-07-10 17:57:28 -050062 spin_lock(&dent->lock);
63 list_add(&fid->dlist, &dent->fidlist);
64 spin_unlock(&dent->lock);
65
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -070066 return 0;
67}
68
69/**
Latchesar Ionkovba176742007-10-17 14:31:07 -050070 * 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_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n",
Wu Fengguang7dd0cdc2008-12-19 16:47:40 -060083 dentry->d_name.name, dentry, uid, any);
Latchesar Ionkovba176742007-10-17 14:31:07 -050084 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
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530100/*
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
Aneesh Kumar K.V7c9e5922011-02-28 17:04:11 +0530128static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
129 uid_t uid, int any)
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -0700130{
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530131 struct dentry *ds;
Latchesar Ionkovba176742007-10-17 14:31:07 -0500132 char **wnames, *uname;
Aneesh Kumar K.V7c9e5922011-02-28 17:04:11 +0530133 int i, n, l, clone, access;
134 struct v9fs_session_info *v9ses;
135 struct p9_fid *fid, *old_fid = NULL;
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -0700136
Aneesh Kumar K.V42869c82011-03-08 16:39:50 +0530137 v9ses = v9fs_dentry2v9ses(dentry);
Latchesar Ionkovba176742007-10-17 14:31:07 -0500138 access = v9ses->flags & V9FS_ACCESS_MASK;
Latchesar Ionkovba176742007-10-17 14:31:07 -0500139 fid = v9fs_fid_find(dentry, uid, any);
140 if (fid)
141 return fid;
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530142 /*
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);
Latchesar Ionkovba176742007-10-17 14:31:07 -0500148 ds = dentry->d_parent;
149 fid = v9fs_fid_find(ds, uid, any);
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530150 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);
Latchesar Ionkovba176742007-10-17 14:31:07 -0500156
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530157 /* 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);
Latchesar Ionkovba176742007-10-17 14:31:07 -0500163
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530164 if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses))
Latchesar Ionkovba176742007-10-17 14:31:07 -0500165 uname = NULL;
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530166 else
167 uname = v9ses->uname;
Latchesar Ionkovba176742007-10-17 14:31:07 -0500168
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530169 fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
170 v9ses->aname);
171 if (IS_ERR(fid))
172 return fid;
Latchesar Ionkovba176742007-10-17 14:31:07 -0500173
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530174 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)
Latchesar Ionkovba176742007-10-17 14:31:07 -0500178 return fid;
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530179 /*
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 }
Latchesar Ionkovba176742007-10-17 14:31:07 -0500190 clone = 1;
191 i = 0;
192 while (i < n) {
193 l = min(n - i, P9_MAXWELEM);
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530194 /*
195 * We need to hold rename lock when doing a multipath
196 * walk to ensure none of the patch component change
197 */
Latchesar Ionkovba176742007-10-17 14:31:07 -0500198 fid = p9_client_walk(fid, l, &wnames[i], clone);
Eric Van Hensbergenc55703d2008-02-06 19:25:08 -0600199 if (IS_ERR(fid)) {
Aneesh Kumar K.V5b0fa202010-03-19 12:47:26 +0000200 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 }
Latchesar Ionkovba176742007-10-17 14:31:07 -0500208 kfree(wnames);
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530209 goto err_out;
Latchesar Ionkovba176742007-10-17 14:31:07 -0500210 }
Aneesh Kumar K.V5b0fa202010-03-19 12:47:26 +0000211 old_fid = fid;
Latchesar Ionkovba176742007-10-17 14:31:07 -0500212 i += l;
213 clone = 0;
214 }
Latchesar Ionkovba176742007-10-17 14:31:07 -0500215 kfree(wnames);
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530216fid_out:
Dan Carpenter8f587df2010-08-04 16:27:45 +0000217 if (!IS_ERR(fid))
218 v9fs_fid_add(dentry, fid);
Aneesh Kumar K.Va534c8d2010-06-30 19:18:50 +0530219err_out:
220 up_read(&v9ses->rename_sem);
Latchesar Ionkovbd238fb2007-07-10 17:57:28 -0500221 return fid;
222}
Eric Van Hensbergen3ed84912005-09-09 13:04:24 -0700223
Aneesh Kumar K.V7c9e5922011-02-28 17:04:11 +0530224/**
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
Aneesh Kumar K.V42869c82011-03-08 16:39:50 +0530240 v9ses = v9fs_dentry2v9ses(dentry);
Aneesh Kumar K.V7c9e5922011-02-28 17:04:11 +0530241 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
Latchesar Ionkovbd238fb2007-07-10 17:57:28 -0500263struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
Eric Van Hensbergenda977b22007-01-26 00:57:06 -0800264{
Latchesar Ionkovba176742007-10-17 14:31:07 -0500265 struct p9_fid *fid, *ret;
Eric Van Hensbergenda977b22007-01-26 00:57:06 -0800266
Latchesar Ionkovba176742007-10-17 14:31:07 -0500267 fid = v9fs_fid_lookup(dentry);
268 if (IS_ERR(fid))
269 return fid;
Eric Van Hensbergenda977b22007-01-26 00:57:06 -0800270
Latchesar Ionkovba176742007-10-17 14:31:07 -0500271 ret = p9_client_walk(fid, 0, NULL, 1);
272 return ret;
Eric Van Hensbergenda977b22007-01-26 00:57:06 -0800273}
Aneesh Kumar K.V3cf387d2011-02-28 17:03:57 +0530274
Aneesh Kumar K.V7c9e5922011-02-28 17:04:11 +0530275static 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}
Aneesh Kumar K.V3cf387d2011-02-28 17:03:57 +0530286
287struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
288{
Aneesh Kumar K.Vdf5d8c82011-03-24 20:38:35 +0530289 int err;
Aneesh Kumar K.V3cf387d2011-02-28 17:03:57 +0530290 struct p9_fid *fid;
291
Aneesh Kumar K.V7c9e5922011-02-28 17:04:11 +0530292 fid = v9fs_fid_clone_with_uid(dentry, 0);
Aneesh Kumar K.V3cf387d2011-02-28 17:03:57 +0530293 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.
Aneesh Kumar K.V3cf387d2011-02-28 17:03:57 +0530300 */
Aneesh Kumar K.Vdf5d8c82011-03-24 20:38:35 +0530301 err = p9_client_open(fid, O_RDWR);
Aneesh Kumar K.V3cf387d2011-02-28 17:03:57 +0530302 if (err < 0) {
303 p9_client_clunk(fid);
304 fid = ERR_PTR(err);
305 goto error_out;
306 }
307error_out:
308 return fid;
309}