]>
Commit | Line | Data |
---|---|---|
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 | ||
bd238fb4 | 44 | int v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid) |
3ed8491c | 45 | { |
bd238fb4 | 46 | struct v9fs_dentry *dent; |
3ed8491c | 47 | |
5d385153 JP |
48 | p9_debug(P9_DEBUG_VFS, "fid %d dentry %s\n", |
49 | fid->fid, dentry->d_name.name); | |
3ed8491c | 50 | |
bd238fb4 LI |
51 | dent = dentry->d_fsdata; |
52 | if (!dent) { | |
53 | dent = kmalloc(sizeof(struct v9fs_dentry), GFP_KERNEL); | |
54 | if (!dent) | |
55 | return -ENOMEM; | |
3ed8491c | 56 | |
bd238fb4 LI |
57 | spin_lock_init(&dent->lock); |
58 | INIT_LIST_HEAD(&dent->fidlist); | |
59 | dentry->d_fsdata = dent; | |
3ed8491c EVH |
60 | } |
61 | ||
bd238fb4 LI |
62 | spin_lock(&dent->lock); |
63 | list_add(&fid->dlist, &dent->fidlist); | |
64 | spin_unlock(&dent->lock); | |
3ed8491c | 65 | |
bd238fb4 | 66 | return 0; |
3ed8491c EVH |
67 | } |
68 | ||
69 | /** | |
ba17674f | 70 | * v9fs_fid_find - retrieve a fid that belongs to the specified uid |
3ed8491c | 71 | * @dentry: dentry to look for fid in |
ba17674f LI |
72 | * @uid: return fid that belongs to the specified user |
73 | * @any: if non-zero, return any fid associated with the dentry | |
3ed8491c EVH |
74 | * |
75 | */ | |
76 | ||
b4642556 | 77 | static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any) |
3ed8491c | 78 | { |
bd238fb4 | 79 | struct v9fs_dentry *dent; |
ba17674f LI |
80 | struct p9_fid *fid, *ret; |
81 | ||
5d385153 | 82 | p9_debug(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n", |
b4642556 EB |
83 | dentry->d_name.name, dentry, from_kuid(&init_user_ns, uid), |
84 | any); | |
ba17674f LI |
85 | dent = (struct v9fs_dentry *) dentry->d_fsdata; |
86 | ret = NULL; | |
87 | if (dent) { | |
88 | spin_lock(&dent->lock); | |
89 | list_for_each_entry(fid, &dent->fidlist, dlist) { | |
b4642556 | 90 | if (any || uid_eq(fid->uid, uid)) { |
ba17674f LI |
91 | ret = fid; |
92 | break; | |
93 | } | |
94 | } | |
95 | spin_unlock(&dent->lock); | |
96 | } | |
bd238fb4 | 97 | |
ba17674f | 98 | return ret; |
bd238fb4 | 99 | } |
3ed8491c | 100 | |
a534c8d1 AK |
101 | /* |
102 | * We need to hold v9ses->rename_sem as long as we hold references | |
103 | * to returned path array. Array element contain pointers to | |
104 | * dentry names. | |
105 | */ | |
106 | static int build_path_from_dentry(struct v9fs_session_info *v9ses, | |
107 | struct dentry *dentry, char ***names) | |
108 | { | |
109 | int n = 0, i; | |
110 | char **wnames; | |
111 | struct dentry *ds; | |
112 | ||
113 | for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent) | |
114 | n++; | |
115 | ||
116 | wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL); | |
117 | if (!wnames) | |
118 | goto err_out; | |
119 | ||
120 | for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent) | |
121 | wnames[i] = (char *)ds->d_name.name; | |
122 | ||
123 | *names = wnames; | |
124 | return n; | |
125 | err_out: | |
126 | return -ENOMEM; | |
127 | } | |
128 | ||
7c9e592e | 129 | static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry, |
b4642556 | 130 | kuid_t uid, int any) |
da977b2c | 131 | { |
a534c8d1 | 132 | struct dentry *ds; |
ba17674f | 133 | char **wnames, *uname; |
7c9e592e AK |
134 | int i, n, l, clone, access; |
135 | struct v9fs_session_info *v9ses; | |
136 | struct p9_fid *fid, *old_fid = NULL; | |
ba17674f | 137 | |
42869c8a | 138 | v9ses = v9fs_dentry2v9ses(dentry); |
ba17674f | 139 | access = v9ses->flags & V9FS_ACCESS_MASK; |
ba17674f LI |
140 | fid = v9fs_fid_find(dentry, uid, any); |
141 | if (fid) | |
142 | return fid; | |
a534c8d1 AK |
143 | /* |
144 | * we don't have a matching fid. To do a TWALK we need | |
145 | * parent fid. We need to prevent rename when we want to | |
146 | * look at the parent. | |
147 | */ | |
148 | down_read(&v9ses->rename_sem); | |
ba17674f LI |
149 | ds = dentry->d_parent; |
150 | fid = v9fs_fid_find(ds, uid, any); | |
a534c8d1 AK |
151 | if (fid) { |
152 | /* Found the parent fid do a lookup with that */ | |
153 | fid = p9_client_walk(fid, 1, (char **)&dentry->d_name.name, 1); | |
154 | goto fid_out; | |
155 | } | |
156 | up_read(&v9ses->rename_sem); | |
ba17674f | 157 | |
a534c8d1 AK |
158 | /* start from the root and try to do a lookup */ |
159 | fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any); | |
160 | if (!fid) { | |
161 | /* the user is not attached to the fs yet */ | |
162 | if (access == V9FS_ACCESS_SINGLE) | |
163 | return ERR_PTR(-EPERM); | |
ba17674f | 164 | |
a534c8d1 AK |
165 | if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses)) |
166 | uname = NULL; | |
167 | else | |
168 | uname = v9ses->uname; | |
ba17674f | 169 | |
a534c8d1 AK |
170 | fid = p9_client_attach(v9ses->clnt, NULL, uname, uid, |
171 | v9ses->aname); | |
172 | if (IS_ERR(fid)) | |
173 | return fid; | |
ba17674f | 174 | |
a534c8d1 AK |
175 | v9fs_fid_add(dentry->d_sb->s_root, fid); |
176 | } | |
177 | /* If we are root ourself just return that */ | |
178 | if (dentry->d_sb->s_root == dentry) | |
ba17674f | 179 | return fid; |
a534c8d1 AK |
180 | /* |
181 | * Do a multipath walk with attached root. | |
182 | * When walking parent we need to make sure we | |
183 | * don't have a parallel rename happening | |
184 | */ | |
185 | down_read(&v9ses->rename_sem); | |
186 | n = build_path_from_dentry(v9ses, dentry, &wnames); | |
187 | if (n < 0) { | |
188 | fid = ERR_PTR(n); | |
189 | goto err_out; | |
190 | } | |
ba17674f LI |
191 | clone = 1; |
192 | i = 0; | |
193 | while (i < n) { | |
194 | l = min(n - i, P9_MAXWELEM); | |
a534c8d1 AK |
195 | /* |
196 | * We need to hold rename lock when doing a multipath | |
197 | * walk to ensure none of the patch component change | |
198 | */ | |
ba17674f | 199 | fid = p9_client_walk(fid, l, &wnames[i], clone); |
c55703d8 | 200 | if (IS_ERR(fid)) { |
5b0fa207 AK |
201 | if (old_fid) { |
202 | /* | |
203 | * If we fail, clunk fid which are mapping | |
204 | * to path component and not the last component | |
205 | * of the path. | |
206 | */ | |
207 | p9_client_clunk(old_fid); | |
208 | } | |
ba17674f | 209 | kfree(wnames); |
a534c8d1 | 210 | goto err_out; |
ba17674f | 211 | } |
5b0fa207 | 212 | old_fid = fid; |
ba17674f LI |
213 | i += l; |
214 | clone = 0; | |
215 | } | |
ba17674f | 216 | kfree(wnames); |
a534c8d1 | 217 | fid_out: |
8f587df4 DC |
218 | if (!IS_ERR(fid)) |
219 | v9fs_fid_add(dentry, fid); | |
a534c8d1 AK |
220 | err_out: |
221 | up_read(&v9ses->rename_sem); | |
bd238fb4 | 222 | return fid; |
da977b2c | 223 | } |
ba17674f | 224 | |
7c9e592e AK |
225 | /** |
226 | * v9fs_fid_lookup - lookup for a fid, try to walk if not found | |
227 | * @dentry: dentry to look for fid in | |
228 | * | |
229 | * Look for a fid in the specified dentry for the current user. | |
230 | * If no fid is found, try to create one walking from a fid from the parent | |
231 | * dentry (if it has one), or the root dentry. If the user haven't accessed | |
232 | * the fs yet, attach now and walk from the root. | |
233 | */ | |
234 | ||
235 | struct p9_fid *v9fs_fid_lookup(struct dentry *dentry) | |
236 | { | |
b4642556 | 237 | kuid_t uid; |
7c9e592e AK |
238 | int any, access; |
239 | struct v9fs_session_info *v9ses; | |
240 | ||
42869c8a | 241 | v9ses = v9fs_dentry2v9ses(dentry); |
7c9e592e AK |
242 | access = v9ses->flags & V9FS_ACCESS_MASK; |
243 | switch (access) { | |
244 | case V9FS_ACCESS_SINGLE: | |
245 | case V9FS_ACCESS_USER: | |
246 | case V9FS_ACCESS_CLIENT: | |
247 | uid = current_fsuid(); | |
248 | any = 0; | |
249 | break; | |
250 | ||
251 | case V9FS_ACCESS_ANY: | |
252 | uid = v9ses->uid; | |
253 | any = 1; | |
254 | break; | |
255 | ||
256 | default: | |
b4642556 | 257 | uid = INVALID_UID; |
7c9e592e AK |
258 | any = 0; |
259 | break; | |
260 | } | |
261 | return v9fs_fid_lookup_with_uid(dentry, uid, any); | |
262 | } | |
263 | ||
ba17674f LI |
264 | struct p9_fid *v9fs_fid_clone(struct dentry *dentry) |
265 | { | |
266 | struct p9_fid *fid, *ret; | |
267 | ||
268 | fid = v9fs_fid_lookup(dentry); | |
269 | if (IS_ERR(fid)) | |
270 | return fid; | |
271 | ||
272 | ret = p9_client_walk(fid, 0, NULL, 1); | |
273 | return ret; | |
274 | } | |
3cf387d7 | 275 | |
b4642556 | 276 | static struct p9_fid *v9fs_fid_clone_with_uid(struct dentry *dentry, kuid_t uid) |
7c9e592e AK |
277 | { |
278 | struct p9_fid *fid, *ret; | |
279 | ||
280 | fid = v9fs_fid_lookup_with_uid(dentry, uid, 0); | |
281 | if (IS_ERR(fid)) | |
282 | return fid; | |
283 | ||
284 | ret = p9_client_walk(fid, 0, NULL, 1); | |
285 | return ret; | |
286 | } | |
3cf387d7 AK |
287 | |
288 | struct p9_fid *v9fs_writeback_fid(struct dentry *dentry) | |
289 | { | |
df5d8c80 | 290 | int err; |
3cf387d7 AK |
291 | struct p9_fid *fid; |
292 | ||
b4642556 | 293 | fid = v9fs_fid_clone_with_uid(dentry, GLOBAL_ROOT_UID); |
3cf387d7 AK |
294 | if (IS_ERR(fid)) |
295 | goto error_out; | |
296 | /* | |
297 | * writeback fid will only be used to write back the | |
298 | * dirty pages. We always request for the open fid in read-write | |
299 | * mode so that a partial page write which result in page | |
300 | * read can work. | |
3cf387d7 | 301 | */ |
df5d8c80 | 302 | err = p9_client_open(fid, O_RDWR); |
3cf387d7 AK |
303 | if (err < 0) { |
304 | p9_client_clunk(fid); | |
305 | fid = ERR_PTR(err); | |
306 | goto error_out; | |
307 | } | |
308 | error_out: | |
309 | return fid; | |
310 | } |