aboutsummaryrefslogtreecommitdiffstats
path: root/fs/9p/fid.c
blob: 7317b39b28159b2e712de1eec7bed5fce2312b3a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
/*
 * V9FS FID Management
 *
 *  Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
 *  Copyright (C) 2005, 2006 by Eric Van Hensbergen <ericvh@gmail.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to:
 *  Free Software Foundation
 *  51 Franklin Street, Fifth Floor
 *  Boston, MA  02111-1301  USA
 *
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/idr.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>

#include "v9fs.h"
#include "v9fs_vfs.h"
#include "fid.h"

/**
 * v9fs_fid_add - add a fid to a dentry
 * @dentry: dentry that the fid is being added to
 * @fid: fid to add
 *
 */

int v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
{
	struct v9fs_dentry *dent;

	P9_DPRINTK(P9_DEBUG_VFS, "fid %d dentry %s\n",
					fid->fid, dentry->d_name.name);

	dent = dentry->d_fsdata;
	if (!dent) {
		dent = kmalloc(sizeof(struct v9fs_dentry), GFP_KERNEL);
		if (!dent)
			return -ENOMEM;

		spin_lock_init(&dent->lock);
		INIT_LIST_HEAD(&dent->fidlist);
		dentry->d_fsdata = dent;
	}

	spin_lock(&dent->lock);
	list_add(&fid->dlist, &dent->fidlist);
	spin_unlock(&dent->lock);

	return 0;
}

/**
 * v9fs_fid_find - retrieve a fid that belongs to the specified uid
 * @dentry: dentry to look for fid in
 * @uid: return fid that belongs to the specified user
 * @any: if non-zero, return any fid associated with the dentry
 *
 */

static struct p9_fid *v9fs_fid_find(struct dentry *dentry, u32 uid, int any)
{
	struct v9fs_dentry *dent;
	struct p9_fid *fid, *ret;

	P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n",
		dentry->d_name.name, dentry, uid, any);
	dent = (struct v9fs_dentry *) dentry->d_fsdata;
	ret = NULL;
	if (dent) {
		spin_lock(&dent->lock);
		list_for_each_entry(fid, &dent->fidlist, dlist) {
			if (any || fid->uid == uid) {
				ret = fid;
				break;
			}
		}
		spin_unlock(&dent->lock);
	}

	return ret;
}

/**
 * v9fs_fid_lookup - lookup for a fid, try to walk if not found
 * @dentry: dentry to look for fid in
 *
 * Look for a fid in the specified dentry for the current user.
 * If no fid is found, try to create one walking from a fid from the parent
 * dentry (if it has one), or the root dentry. If the user haven't accessed
 * the fs yet, attach now and walk from the root.
 */

struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
{
	int i, n, l, clone, any, access;
	u32 uid;
	struct p9_fid *fid, *old_fid = NULL;
	struct dentry *d, *ds;
	struct v9fs_session_info *v9ses;
	char **wnames, *uname;

	v9ses = v9fs_inode2v9ses(dentry->d_inode);
	access = v9ses->flags & V9FS_ACCESS_MASK;
	switch (access) {
	case V9FS_ACCESS_SINGLE:
	case V9FS_ACCESS_USER:
		uid = current_fsuid();
		any = 0;
		break;

	case V9FS_ACCESS_ANY:
		uid = v9ses->uid;
		any = 1;
		break;

	default:
		uid = ~0;
		any = 0;
		break;
	}

	fid = v9fs_fid_find(dentry, uid, any);
	if (fid)
		return fid;

	ds = dentry->d_parent;
	fid = v9fs_fid_find(ds, uid, any);
	if (!fid) { /* walk from the root */
		n = 0;
		for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent)
			n++;

		fid = v9fs_fid_find(ds, uid, any);
		if (!fid) { /* the user is not attached to the fs yet */
			if (access == V9FS_ACCESS_SINGLE)
				return ERR_PTR(-EPERM);

			if (v9fs_proto_dotu(v9ses))
				uname = NULL;
			else
				uname = v9ses->uname;

			fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
				v9ses->aname);

			if (IS_ERR(fid))
				return fid;

			v9fs_fid_add(ds, fid);
		}
	} else /* walk from the parent */
		n = 1;

	if (ds == dentry)
		return fid;

	wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL);
	if (!wnames)
		return ERR_PTR(-ENOMEM);

	for (d = dentry, i = (n-1); i >= 0; i--, d = d->d_parent)
		wnames[i] = (char *) d->d_name.name;

	clone = 1;
	i = 0;
	while (i < n) {
		l = min(n - i, P9_MAXWELEM);
		fid = p9_client_walk(fid, l, &wnames[i], clone);
		if (IS_ERR(fid)) {
			if (old_fid) {
				/*
				 * If we fail, clunk fid which are mapping
				 * to path component and not the last component
				 * of the path.
				 */
				p9_client_clunk(old_fid);
			}
			kfree(wnames);
			return fid;
		}
		old_fid = fid;
		i += l;
		clone = 0;
	}

	kfree(wnames);
	v9fs_fid_add(dentry, fid);
	return fid;
}

struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
{
	struct p9_fid *fid, *ret;

	fid = v9fs_fid_lookup(dentry);
	if (IS_ERR(fid))
		return fid;

	ret = p9_client_walk(fid, 0, NULL, 1);
	return ret;
}