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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/sched.h> |
28 | #include <linux/idr.h> |
29 | #include <net/9p/9p.h> |
30 | #include <net/9p/client.h> |
31 | |
32 | #include "v9fs.h" |
33 | #include "v9fs_vfs.h" |
34 | #include "fid.h" |
35 | |
36 | /** |
37 | * v9fs_fid_add - add a fid to a dentry |
38 | * @dentry: dentry that the fid is being added to |
39 | * @fid: fid to add |
40 | * |
41 | */ |
42 | |
43 | int v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid) |
44 | { |
45 | struct v9fs_dentry *dent; |
46 | |
47 | P9_DPRINTK(P9_DEBUG_VFS, "fid %d dentry %s\n", |
48 | fid->fid, dentry->d_name.name); |
49 | |
50 | dent = dentry->d_fsdata; |
51 | if (!dent) { |
52 | dent = kmalloc(sizeof(struct v9fs_dentry), GFP_KERNEL); |
53 | if (!dent) |
54 | return -ENOMEM; |
55 | |
56 | spin_lock_init(&dent->lock); |
57 | INIT_LIST_HEAD(&dent->fidlist); |
58 | dentry->d_fsdata = dent; |
59 | } |
60 | |
61 | spin_lock(&dent->lock); |
62 | list_add(&fid->dlist, &dent->fidlist); |
63 | spin_unlock(&dent->lock); |
64 | |
65 | return 0; |
66 | } |
67 | |
68 | /** |
69 | * v9fs_fid_find - retrieve a fid that belongs to the specified uid |
70 | * @dentry: dentry to look for fid in |
71 | * @uid: return fid that belongs to the specified user |
72 | * @any: if non-zero, return any fid associated with the dentry |
73 | * |
74 | */ |
75 | |
76 | static struct p9_fid *v9fs_fid_find(struct dentry *dentry, u32 uid, int any) |
77 | { |
78 | struct v9fs_dentry *dent; |
79 | struct p9_fid *fid, *ret; |
80 | |
81 | P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n", |
82 | dentry->d_name.name, dentry, uid, any); |
83 | dent = (struct v9fs_dentry *) dentry->d_fsdata; |
84 | ret = NULL; |
85 | if (dent) { |
86 | spin_lock(&dent->lock); |
87 | list_for_each_entry(fid, &dent->fidlist, dlist) { |
88 | if (any || fid->uid == uid) { |
89 | ret = fid; |
90 | break; |
91 | } |
92 | } |
93 | spin_unlock(&dent->lock); |
94 | } |
95 | |
96 | return ret; |
97 | } |
98 | |
99 | /** |
100 | * v9fs_fid_lookup - lookup for a fid, try to walk if not found |
101 | * @dentry: dentry to look for fid in |
102 | * |
103 | * Look for a fid in the specified dentry for the current user. |
104 | * If no fid is found, try to create one walking from a fid from the parent |
105 | * dentry (if it has one), or the root dentry. If the user haven't accessed |
106 | * the fs yet, attach now and walk from the root. |
107 | */ |
108 | |
109 | struct p9_fid *v9fs_fid_lookup(struct dentry *dentry) |
110 | { |
111 | int i, n, l, clone, any, access; |
112 | u32 uid; |
113 | struct p9_fid *fid; |
114 | struct dentry *d, *ds; |
115 | struct v9fs_session_info *v9ses; |
116 | char **wnames, *uname; |
117 | |
118 | v9ses = v9fs_inode2v9ses(dentry->d_inode); |
119 | access = v9ses->flags & V9FS_ACCESS_MASK; |
120 | switch (access) { |
121 | case V9FS_ACCESS_SINGLE: |
122 | case V9FS_ACCESS_USER: |
123 | uid = current_fsuid(); |
124 | any = 0; |
125 | break; |
126 | |
127 | case V9FS_ACCESS_ANY: |
128 | uid = v9ses->uid; |
129 | any = 1; |
130 | break; |
131 | |
132 | default: |
133 | uid = ~0; |
134 | any = 0; |
135 | break; |
136 | } |
137 | |
138 | fid = v9fs_fid_find(dentry, uid, any); |
139 | if (fid) |
140 | return fid; |
141 | |
142 | ds = dentry->d_parent; |
143 | fid = v9fs_fid_find(ds, uid, any); |
144 | if (!fid) { /* walk from the root */ |
145 | n = 0; |
146 | for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent) |
147 | n++; |
148 | |
149 | fid = v9fs_fid_find(ds, uid, any); |
150 | if (!fid) { /* the user is not attached to the fs yet */ |
151 | if (access == V9FS_ACCESS_SINGLE) |
152 | return ERR_PTR(-EPERM); |
153 | |
154 | if (v9fs_extended(v9ses)) |
155 | uname = NULL; |
156 | else |
157 | uname = v9ses->uname; |
158 | |
159 | fid = p9_client_attach(v9ses->clnt, NULL, uname, uid, |
160 | v9ses->aname); |
161 | |
162 | if (IS_ERR(fid)) |
163 | return fid; |
164 | |
165 | v9fs_fid_add(ds, fid); |
166 | } |
167 | } else /* walk from the parent */ |
168 | n = 1; |
169 | |
170 | if (ds == dentry) |
171 | return fid; |
172 | |
173 | wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL); |
174 | if (!wnames) |
175 | return ERR_PTR(-ENOMEM); |
176 | |
177 | for (d = dentry, i = (n-1); i >= 0; i--, d = d->d_parent) |
178 | wnames[i] = (char *) d->d_name.name; |
179 | |
180 | clone = 1; |
181 | i = 0; |
182 | while (i < n) { |
183 | l = min(n - i, P9_MAXWELEM); |
184 | fid = p9_client_walk(fid, l, &wnames[i], clone); |
185 | if (IS_ERR(fid)) { |
186 | kfree(wnames); |
187 | return fid; |
188 | } |
189 | |
190 | i += l; |
191 | clone = 0; |
192 | } |
193 | |
194 | kfree(wnames); |
195 | v9fs_fid_add(dentry, fid); |
196 | return fid; |
197 | } |
198 | |
199 | struct p9_fid *v9fs_fid_clone(struct dentry *dentry) |
200 | { |
201 | struct p9_fid *fid, *ret; |
202 | |
203 | fid = v9fs_fid_lookup(dentry); |
204 | if (IS_ERR(fid)) |
205 | return fid; |
206 | |
207 | ret = p9_client_walk(fid, 0, NULL, 1); |
208 | return ret; |
209 | } |
210 |
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