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 | ||
bd238fb4 | 44 | int 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); |
bd238fb4 | 49 | return 0; |
3ed8491c EVH |
50 | } |
51 | ||
52 | /** | |
ba17674f | 53 | * v9fs_fid_find - retrieve a fid that belongs to the specified uid |
3ed8491c | 54 | * @dentry: dentry to look for fid in |
ba17674f LI |
55 | * @uid: return fid that belongs to the specified user |
56 | * @any: if non-zero, return any fid associated with the dentry | |
3ed8491c EVH |
57 | * |
58 | */ | |
59 | ||
b4642556 | 60 | static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any) |
3ed8491c | 61 | { |
ba17674f LI |
62 | struct p9_fid *fid, *ret; |
63 | ||
5d385153 | 64 | p9_debug(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n", |
b4642556 EB |
65 | dentry->d_name.name, dentry, from_kuid(&init_user_ns, uid), |
66 | any); | |
ba17674f | 67 | ret = NULL; |
aaeb7ecf AV |
68 | /* we'll recheck under lock if there's anything to look in */ |
69 | if (dentry->d_fsdata) { | |
70 | struct hlist_head *h = (struct hlist_head *)&dentry->d_fsdata; | |
c4d30967 | 71 | struct hlist_node *n; |
634095da | 72 | spin_lock(&dentry->d_lock); |
aaeb7ecf | 73 | hlist_for_each_entry(fid, n, h, dlist) { |
b4642556 | 74 | if (any || uid_eq(fid->uid, uid)) { |
ba17674f LI |
75 | ret = fid; |
76 | break; | |
77 | } | |
78 | } | |
634095da | 79 | spin_unlock(&dentry->d_lock); |
ba17674f | 80 | } |
bd238fb4 | 81 | |
ba17674f | 82 | return ret; |
bd238fb4 | 83 | } |
3ed8491c | 84 | |
a534c8d1 AK |
85 | /* |
86 | * We need to hold v9ses->rename_sem as long as we hold references | |
87 | * to returned path array. Array element contain pointers to | |
88 | * dentry names. | |
89 | */ | |
90 | static int build_path_from_dentry(struct v9fs_session_info *v9ses, | |
91 | struct dentry *dentry, char ***names) | |
92 | { | |
93 | int n = 0, i; | |
94 | char **wnames; | |
95 | struct dentry *ds; | |
96 | ||
97 | for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent) | |
98 | n++; | |
99 | ||
100 | wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL); | |
101 | if (!wnames) | |
102 | goto err_out; | |
103 | ||
104 | for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent) | |
105 | wnames[i] = (char *)ds->d_name.name; | |
106 | ||
107 | *names = wnames; | |
108 | return n; | |
109 | err_out: | |
110 | return -ENOMEM; | |
111 | } | |
112 | ||
7c9e592e | 113 | static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry, |
b4642556 | 114 | kuid_t uid, int any) |
da977b2c | 115 | { |
a534c8d1 | 116 | struct dentry *ds; |
ba17674f | 117 | char **wnames, *uname; |
7c9e592e AK |
118 | int i, n, l, clone, access; |
119 | struct v9fs_session_info *v9ses; | |
120 | struct p9_fid *fid, *old_fid = NULL; | |
ba17674f | 121 | |
42869c8a | 122 | v9ses = v9fs_dentry2v9ses(dentry); |
ba17674f | 123 | access = v9ses->flags & V9FS_ACCESS_MASK; |
ba17674f LI |
124 | fid = v9fs_fid_find(dentry, uid, any); |
125 | if (fid) | |
126 | return fid; | |
a534c8d1 AK |
127 | /* |
128 | * we don't have a matching fid. To do a TWALK we need | |
129 | * parent fid. We need to prevent rename when we want to | |
130 | * look at the parent. | |
131 | */ | |
132 | down_read(&v9ses->rename_sem); | |
ba17674f LI |
133 | ds = dentry->d_parent; |
134 | fid = v9fs_fid_find(ds, uid, any); | |
a534c8d1 AK |
135 | if (fid) { |
136 | /* Found the parent fid do a lookup with that */ | |
137 | fid = p9_client_walk(fid, 1, (char **)&dentry->d_name.name, 1); | |
138 | goto fid_out; | |
139 | } | |
140 | up_read(&v9ses->rename_sem); | |
ba17674f | 141 | |
a534c8d1 AK |
142 | /* start from the root and try to do a lookup */ |
143 | fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any); | |
144 | if (!fid) { | |
145 | /* the user is not attached to the fs yet */ | |
146 | if (access == V9FS_ACCESS_SINGLE) | |
147 | return ERR_PTR(-EPERM); | |
ba17674f | 148 | |
a534c8d1 AK |
149 | if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses)) |
150 | uname = NULL; | |
151 | else | |
152 | uname = v9ses->uname; | |
ba17674f | 153 | |
a534c8d1 AK |
154 | fid = p9_client_attach(v9ses->clnt, NULL, uname, uid, |
155 | v9ses->aname); | |
156 | if (IS_ERR(fid)) | |
157 | return fid; | |
ba17674f | 158 | |
a534c8d1 AK |
159 | v9fs_fid_add(dentry->d_sb->s_root, fid); |
160 | } | |
161 | /* If we are root ourself just return that */ | |
162 | if (dentry->d_sb->s_root == dentry) | |
ba17674f | 163 | return fid; |
a534c8d1 AK |
164 | /* |
165 | * Do a multipath walk with attached root. | |
166 | * When walking parent we need to make sure we | |
167 | * don't have a parallel rename happening | |
168 | */ | |
169 | down_read(&v9ses->rename_sem); | |
170 | n = build_path_from_dentry(v9ses, dentry, &wnames); | |
171 | if (n < 0) { | |
172 | fid = ERR_PTR(n); | |
173 | goto err_out; | |
174 | } | |
ba17674f LI |
175 | clone = 1; |
176 | i = 0; | |
177 | while (i < n) { | |
178 | l = min(n - i, P9_MAXWELEM); | |
a534c8d1 AK |
179 | /* |
180 | * We need to hold rename lock when doing a multipath | |
181 | * walk to ensure none of the patch component change | |
182 | */ | |
ba17674f | 183 | fid = p9_client_walk(fid, l, &wnames[i], clone); |
c55703d8 | 184 | if (IS_ERR(fid)) { |
5b0fa207 AK |
185 | if (old_fid) { |
186 | /* | |
187 | * If we fail, clunk fid which are mapping | |
188 | * to path component and not the last component | |
189 | * of the path. | |
190 | */ | |
191 | p9_client_clunk(old_fid); | |
192 | } | |
ba17674f | 193 | kfree(wnames); |
a534c8d1 | 194 | goto err_out; |
ba17674f | 195 | } |
5b0fa207 | 196 | old_fid = fid; |
ba17674f LI |
197 | i += l; |
198 | clone = 0; | |
199 | } | |
ba17674f | 200 | kfree(wnames); |
a534c8d1 | 201 | fid_out: |
8f587df4 DC |
202 | if (!IS_ERR(fid)) |
203 | v9fs_fid_add(dentry, fid); | |
a534c8d1 AK |
204 | err_out: |
205 | up_read(&v9ses->rename_sem); | |
bd238fb4 | 206 | return fid; |
da977b2c | 207 | } |
ba17674f | 208 | |
7c9e592e AK |
209 | /** |
210 | * v9fs_fid_lookup - lookup for a fid, try to walk if not found | |
211 | * @dentry: dentry to look for fid in | |
212 | * | |
213 | * Look for a fid in the specified dentry for the current user. | |
214 | * If no fid is found, try to create one walking from a fid from the parent | |
215 | * dentry (if it has one), or the root dentry. If the user haven't accessed | |
216 | * the fs yet, attach now and walk from the root. | |
217 | */ | |
218 | ||
219 | struct p9_fid *v9fs_fid_lookup(struct dentry *dentry) | |
220 | { | |
b4642556 | 221 | kuid_t uid; |
7c9e592e AK |
222 | int any, access; |
223 | struct v9fs_session_info *v9ses; | |
224 | ||
42869c8a | 225 | v9ses = v9fs_dentry2v9ses(dentry); |
7c9e592e AK |
226 | access = v9ses->flags & V9FS_ACCESS_MASK; |
227 | switch (access) { | |
228 | case V9FS_ACCESS_SINGLE: | |
229 | case V9FS_ACCESS_USER: | |
230 | case V9FS_ACCESS_CLIENT: | |
231 | uid = current_fsuid(); | |
232 | any = 0; | |
233 | break; | |
234 | ||
235 | case V9FS_ACCESS_ANY: | |
236 | uid = v9ses->uid; | |
237 | any = 1; | |
238 | break; | |
239 | ||
240 | default: | |
b4642556 | 241 | uid = INVALID_UID; |
7c9e592e AK |
242 | any = 0; |
243 | break; | |
244 | } | |
245 | return v9fs_fid_lookup_with_uid(dentry, uid, any); | |
246 | } | |
247 | ||
ba17674f LI |
248 | struct p9_fid *v9fs_fid_clone(struct dentry *dentry) |
249 | { | |
250 | struct p9_fid *fid, *ret; | |
251 | ||
252 | fid = v9fs_fid_lookup(dentry); | |
253 | if (IS_ERR(fid)) | |
254 | return fid; | |
255 | ||
256 | ret = p9_client_walk(fid, 0, NULL, 1); | |
257 | return ret; | |
258 | } | |
3cf387d7 | 259 | |
b4642556 | 260 | static struct p9_fid *v9fs_fid_clone_with_uid(struct dentry *dentry, kuid_t uid) |
7c9e592e AK |
261 | { |
262 | struct p9_fid *fid, *ret; | |
263 | ||
264 | fid = v9fs_fid_lookup_with_uid(dentry, uid, 0); | |
265 | if (IS_ERR(fid)) | |
266 | return fid; | |
267 | ||
268 | ret = p9_client_walk(fid, 0, NULL, 1); | |
269 | return ret; | |
270 | } | |
3cf387d7 AK |
271 | |
272 | struct p9_fid *v9fs_writeback_fid(struct dentry *dentry) | |
273 | { | |
df5d8c80 | 274 | int err; |
3cf387d7 AK |
275 | struct p9_fid *fid; |
276 | ||
b4642556 | 277 | fid = v9fs_fid_clone_with_uid(dentry, GLOBAL_ROOT_UID); |
3cf387d7 AK |
278 | if (IS_ERR(fid)) |
279 | goto error_out; | |
280 | /* | |
281 | * writeback fid will only be used to write back the | |
282 | * dirty pages. We always request for the open fid in read-write | |
283 | * mode so that a partial page write which result in page | |
284 | * read can work. | |
3cf387d7 | 285 | */ |
df5d8c80 | 286 | err = p9_client_open(fid, O_RDWR); |
3cf387d7 AK |
287 | if (err < 0) { |
288 | p9_client_clunk(fid); | |
289 | fid = ERR_PTR(err); | |
290 | goto error_out; | |
291 | } | |
292 | error_out: | |
293 | return fid; | |
294 | } |