Commit | Line | Data |
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3ed8491c EVH |
1 | /* |
2 | * V9FS FID Management | |
3 | * | |
ba17674f | 4 | * Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net> |
46f6dac2 | 5 | * Copyright (C) 2005, 2006 by Eric Van Hensbergen <ericvh@gmail.com> |
3ed8491c EVH |
6 | * |
7 | * This program is free software; you can redistribute it and/or modify | |
42e8c509 EVH |
8 | * it under the terms of the GNU General Public License version 2 |
9 | * as published by the Free Software Foundation. | |
3ed8491c EVH |
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 | ||
3ed8491c EVH |
24 | #include <linux/module.h> |
25 | #include <linux/errno.h> | |
26 | #include <linux/fs.h> | |
5a0e3ad6 | 27 | #include <linux/slab.h> |
914e2637 | 28 | #include <linux/sched.h> |
3ed8491c | 29 | #include <linux/idr.h> |
bd238fb4 LI |
30 | #include <net/9p/9p.h> |
31 | #include <net/9p/client.h> | |
3ed8491c | 32 | |
3ed8491c | 33 | #include "v9fs.h" |
3ed8491c | 34 | #include "v9fs_vfs.h" |
3ed8491c EVH |
35 | #include "fid.h" |
36 | ||
37 | /** | |
ba17674f LI |
38 | * v9fs_fid_add - add a fid to a dentry |
39 | * @dentry: dentry that the fid is being added to | |
3ed8491c | 40 | * @fid: fid to add |
3ed8491c EVH |
41 | * |
42 | */ | |
43 | ||
2ea03e1d | 44 | void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid) |
3ed8491c | 45 | { |
634095da | 46 | spin_lock(&dentry->d_lock); |
aaeb7ecf | 47 | hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata); |
634095da | 48 | spin_unlock(&dentry->d_lock); |
3ed8491c EVH |
49 | } |
50 | ||
51 | /** | |
ba17674f | 52 | * v9fs_fid_find - retrieve a fid that belongs to the specified uid |
3ed8491c | 53 | * @dentry: dentry to look for fid in |
ba17674f LI |
54 | * @uid: return fid that belongs to the specified user |
55 | * @any: if non-zero, return any fid associated with the dentry | |
3ed8491c EVH |
56 | * |
57 | */ | |
58 | ||
b4642556 | 59 | static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any) |
3ed8491c | 60 | { |
ba17674f LI |
61 | struct p9_fid *fid, *ret; |
62 | ||
5d385153 | 63 | p9_debug(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n", |
b4642556 EB |
64 | dentry->d_name.name, dentry, from_kuid(&init_user_ns, uid), |
65 | any); | |
ba17674f | 66 | ret = NULL; |
aaeb7ecf AV |
67 | /* we'll recheck under lock if there's anything to look in */ |
68 | if (dentry->d_fsdata) { | |
69 | struct hlist_head *h = (struct hlist_head *)&dentry->d_fsdata; | |
c4d30967 | 70 | struct hlist_node *n; |
634095da | 71 | spin_lock(&dentry->d_lock); |
aaeb7ecf | 72 | hlist_for_each_entry(fid, n, h, dlist) { |
b4642556 | 73 | if (any || uid_eq(fid->uid, uid)) { |
ba17674f LI |
74 | ret = fid; |
75 | break; | |
76 | } | |
77 | } | |
634095da | 78 | spin_unlock(&dentry->d_lock); |
ba17674f | 79 | } |
bd238fb4 | 80 | |
ba17674f | 81 | return ret; |
bd238fb4 | 82 | } |
3ed8491c | 83 | |
a534c8d1 AK |
84 | /* |
85 | * We need to hold v9ses->rename_sem as long as we hold references | |
86 | * to returned path array. Array element contain pointers to | |
87 | * dentry names. | |
88 | */ | |
89 | static int build_path_from_dentry(struct v9fs_session_info *v9ses, | |
90 | struct dentry *dentry, char ***names) | |
91 | { | |
92 | int n = 0, i; | |
93 | char **wnames; | |
94 | struct dentry *ds; | |
95 | ||
96 | for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent) | |
97 | n++; | |
98 | ||
99 | wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL); | |
100 | if (!wnames) | |
101 | goto err_out; | |
102 | ||
103 | for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent) | |
104 | wnames[i] = (char *)ds->d_name.name; | |
105 | ||
106 | *names = wnames; | |
107 | return n; | |
108 | err_out: | |
109 | return -ENOMEM; | |
110 | } | |
111 | ||
7c9e592e | 112 | static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry, |
b4642556 | 113 | kuid_t uid, int any) |
da977b2c | 114 | { |
a534c8d1 | 115 | struct dentry *ds; |
ba17674f | 116 | char **wnames, *uname; |
7c9e592e AK |
117 | int i, n, l, clone, access; |
118 | struct v9fs_session_info *v9ses; | |
119 | struct p9_fid *fid, *old_fid = NULL; | |
ba17674f | 120 | |
42869c8a | 121 | v9ses = v9fs_dentry2v9ses(dentry); |
ba17674f | 122 | access = v9ses->flags & V9FS_ACCESS_MASK; |
ba17674f LI |
123 | fid = v9fs_fid_find(dentry, uid, any); |
124 | if (fid) | |
125 | return fid; | |
a534c8d1 AK |
126 | /* |
127 | * we don't have a matching fid. To do a TWALK we need | |
128 | * parent fid. We need to prevent rename when we want to | |
129 | * look at the parent. | |
130 | */ | |
131 | down_read(&v9ses->rename_sem); | |
ba17674f LI |
132 | ds = dentry->d_parent; |
133 | fid = v9fs_fid_find(ds, uid, any); | |
a534c8d1 AK |
134 | if (fid) { |
135 | /* Found the parent fid do a lookup with that */ | |
136 | fid = p9_client_walk(fid, 1, (char **)&dentry->d_name.name, 1); | |
137 | goto fid_out; | |
138 | } | |
139 | up_read(&v9ses->rename_sem); | |
ba17674f | 140 | |
a534c8d1 AK |
141 | /* start from the root and try to do a lookup */ |
142 | fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any); | |
143 | if (!fid) { | |
144 | /* the user is not attached to the fs yet */ | |
145 | if (access == V9FS_ACCESS_SINGLE) | |
146 | return ERR_PTR(-EPERM); | |
ba17674f | 147 | |
a534c8d1 AK |
148 | if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses)) |
149 | uname = NULL; | |
150 | else | |
151 | uname = v9ses->uname; | |
ba17674f | 152 | |
a534c8d1 AK |
153 | fid = p9_client_attach(v9ses->clnt, NULL, uname, uid, |
154 | v9ses->aname); | |
155 | if (IS_ERR(fid)) | |
156 | return fid; | |
ba17674f | 157 | |
a534c8d1 AK |
158 | v9fs_fid_add(dentry->d_sb->s_root, fid); |
159 | } | |
160 | /* If we are root ourself just return that */ | |
161 | if (dentry->d_sb->s_root == dentry) | |
ba17674f | 162 | return fid; |
a534c8d1 AK |
163 | /* |
164 | * Do a multipath walk with attached root. | |
165 | * When walking parent we need to make sure we | |
166 | * don't have a parallel rename happening | |
167 | */ | |
168 | down_read(&v9ses->rename_sem); | |
169 | n = build_path_from_dentry(v9ses, dentry, &wnames); | |
170 | if (n < 0) { | |
171 | fid = ERR_PTR(n); | |
172 | goto err_out; | |
173 | } | |
ba17674f LI |
174 | clone = 1; |
175 | i = 0; | |
176 | while (i < n) { | |
177 | l = min(n - i, P9_MAXWELEM); | |
a534c8d1 AK |
178 | /* |
179 | * We need to hold rename lock when doing a multipath | |
180 | * walk to ensure none of the patch component change | |
181 | */ | |
ba17674f | 182 | fid = p9_client_walk(fid, l, &wnames[i], clone); |
c55703d8 | 183 | if (IS_ERR(fid)) { |
5b0fa207 AK |
184 | if (old_fid) { |
185 | /* | |
186 | * If we fail, clunk fid which are mapping | |
187 | * to path component and not the last component | |
188 | * of the path. | |
189 | */ | |
190 | p9_client_clunk(old_fid); | |
191 | } | |
ba17674f | 192 | kfree(wnames); |
a534c8d1 | 193 | goto err_out; |
ba17674f | 194 | } |
5b0fa207 | 195 | old_fid = fid; |
ba17674f LI |
196 | i += l; |
197 | clone = 0; | |
198 | } | |
ba17674f | 199 | kfree(wnames); |
a534c8d1 | 200 | fid_out: |
8f587df4 DC |
201 | if (!IS_ERR(fid)) |
202 | v9fs_fid_add(dentry, fid); | |
a534c8d1 AK |
203 | err_out: |
204 | up_read(&v9ses->rename_sem); | |
bd238fb4 | 205 | return fid; |
da977b2c | 206 | } |
ba17674f | 207 | |
7c9e592e AK |
208 | /** |
209 | * v9fs_fid_lookup - lookup for a fid, try to walk if not found | |
210 | * @dentry: dentry to look for fid in | |
211 | * | |
212 | * Look for a fid in the specified dentry for the current user. | |
213 | * If no fid is found, try to create one walking from a fid from the parent | |
214 | * dentry (if it has one), or the root dentry. If the user haven't accessed | |
215 | * the fs yet, attach now and walk from the root. | |
216 | */ | |
217 | ||
218 | struct p9_fid *v9fs_fid_lookup(struct dentry *dentry) | |
219 | { | |
b4642556 | 220 | kuid_t uid; |
7c9e592e AK |
221 | int any, access; |
222 | struct v9fs_session_info *v9ses; | |
223 | ||
42869c8a | 224 | v9ses = v9fs_dentry2v9ses(dentry); |
7c9e592e AK |
225 | access = v9ses->flags & V9FS_ACCESS_MASK; |
226 | switch (access) { | |
227 | case V9FS_ACCESS_SINGLE: | |
228 | case V9FS_ACCESS_USER: | |
229 | case V9FS_ACCESS_CLIENT: | |
230 | uid = current_fsuid(); | |
231 | any = 0; | |
232 | break; | |
233 | ||
234 | case V9FS_ACCESS_ANY: | |
235 | uid = v9ses->uid; | |
236 | any = 1; | |
237 | break; | |
238 | ||
239 | default: | |
b4642556 | 240 | uid = INVALID_UID; |
7c9e592e AK |
241 | any = 0; |
242 | break; | |
243 | } | |
244 | return v9fs_fid_lookup_with_uid(dentry, uid, any); | |
245 | } | |
246 | ||
ba17674f LI |
247 | struct p9_fid *v9fs_fid_clone(struct dentry *dentry) |
248 | { | |
249 | struct p9_fid *fid, *ret; | |
250 | ||
251 | fid = v9fs_fid_lookup(dentry); | |
252 | if (IS_ERR(fid)) | |
253 | return fid; | |
254 | ||
255 | ret = p9_client_walk(fid, 0, NULL, 1); | |
256 | return ret; | |
257 | } | |
3cf387d7 | 258 | |
b4642556 | 259 | static struct p9_fid *v9fs_fid_clone_with_uid(struct dentry *dentry, kuid_t uid) |
7c9e592e AK |
260 | { |
261 | struct p9_fid *fid, *ret; | |
262 | ||
263 | fid = v9fs_fid_lookup_with_uid(dentry, uid, 0); | |
264 | if (IS_ERR(fid)) | |
265 | return fid; | |
266 | ||
267 | ret = p9_client_walk(fid, 0, NULL, 1); | |
268 | return ret; | |
269 | } | |
3cf387d7 AK |
270 | |
271 | struct p9_fid *v9fs_writeback_fid(struct dentry *dentry) | |
272 | { | |
df5d8c80 | 273 | int err; |
3cf387d7 AK |
274 | struct p9_fid *fid; |
275 | ||
b4642556 | 276 | fid = v9fs_fid_clone_with_uid(dentry, GLOBAL_ROOT_UID); |
3cf387d7 AK |
277 | if (IS_ERR(fid)) |
278 | goto error_out; | |
279 | /* | |
280 | * writeback fid will only be used to write back the | |
281 | * dirty pages. We always request for the open fid in read-write | |
282 | * mode so that a partial page write which result in page | |
283 | * read can work. | |
3cf387d7 | 284 | */ |
df5d8c80 | 285 | err = p9_client_open(fid, O_RDWR); |
3cf387d7 AK |
286 | if (err < 0) { |
287 | p9_client_clunk(fid); | |
288 | fid = ERR_PTR(err); | |
289 | goto error_out; | |
290 | } | |
291 | error_out: | |
292 | return fid; | |
293 | } |