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b6450630 SF |
1 | /* |
2 | * Copyright (C) 2010-2017 Junjiro R. Okajima | |
3 | * | |
4 | * This program, aufs is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program. If not, see <http://www.gnu.org/licenses/>. | |
16 | */ | |
17 | ||
18 | /* | |
19 | * dynamically customizable operations for regular files | |
20 | */ | |
21 | ||
22 | #include "aufs.h" | |
23 | ||
24 | #define DyPrSym(key) AuDbgSym(key->dk_op.dy_hop) | |
25 | ||
26 | /* | |
27 | * How large will these lists be? | |
28 | * Usually just a few elements, 20-30 at most for each, I guess. | |
29 | */ | |
30 | static struct au_sphlhead dynop[AuDyLast]; | |
31 | ||
32 | static struct au_dykey *dy_gfind_get(struct au_sphlhead *sphl, const void *h_op) | |
33 | { | |
34 | struct au_dykey *key, *tmp; | |
35 | struct hlist_head *head; | |
36 | ||
37 | key = NULL; | |
38 | head = &sphl->head; | |
39 | rcu_read_lock(); | |
40 | hlist_for_each_entry_rcu(tmp, head, dk_hnode) | |
41 | if (tmp->dk_op.dy_hop == h_op) { | |
42 | key = tmp; | |
43 | kref_get(&key->dk_kref); | |
44 | break; | |
45 | } | |
46 | rcu_read_unlock(); | |
47 | ||
48 | return key; | |
49 | } | |
50 | ||
51 | static struct au_dykey *dy_bradd(struct au_branch *br, struct au_dykey *key) | |
52 | { | |
53 | struct au_dykey **k, *found; | |
54 | const void *h_op = key->dk_op.dy_hop; | |
55 | int i; | |
56 | ||
57 | found = NULL; | |
58 | k = br->br_dykey; | |
59 | for (i = 0; i < AuBrDynOp; i++) | |
60 | if (k[i]) { | |
61 | if (k[i]->dk_op.dy_hop == h_op) { | |
62 | found = k[i]; | |
63 | break; | |
64 | } | |
65 | } else | |
66 | break; | |
67 | if (!found) { | |
68 | spin_lock(&br->br_dykey_lock); | |
69 | for (; i < AuBrDynOp; i++) | |
70 | if (k[i]) { | |
71 | if (k[i]->dk_op.dy_hop == h_op) { | |
72 | found = k[i]; | |
73 | break; | |
74 | } | |
75 | } else { | |
76 | k[i] = key; | |
77 | break; | |
78 | } | |
79 | spin_unlock(&br->br_dykey_lock); | |
80 | BUG_ON(i == AuBrDynOp); /* expand the array */ | |
81 | } | |
82 | ||
83 | return found; | |
84 | } | |
85 | ||
86 | /* kref_get() if @key is already added */ | |
87 | static struct au_dykey *dy_gadd(struct au_sphlhead *sphl, struct au_dykey *key) | |
88 | { | |
89 | struct au_dykey *tmp, *found; | |
90 | struct hlist_head *head; | |
91 | const void *h_op = key->dk_op.dy_hop; | |
92 | ||
93 | found = NULL; | |
94 | head = &sphl->head; | |
95 | spin_lock(&sphl->spin); | |
96 | hlist_for_each_entry(tmp, head, dk_hnode) | |
97 | if (tmp->dk_op.dy_hop == h_op) { | |
98 | kref_get(&tmp->dk_kref); | |
99 | found = tmp; | |
100 | break; | |
101 | } | |
102 | if (!found) | |
103 | hlist_add_head_rcu(&key->dk_hnode, head); | |
104 | spin_unlock(&sphl->spin); | |
105 | ||
106 | if (!found) | |
107 | DyPrSym(key); | |
108 | return found; | |
109 | } | |
110 | ||
111 | static void dy_free_rcu(struct rcu_head *rcu) | |
112 | { | |
113 | struct au_dykey *key; | |
114 | ||
115 | key = container_of(rcu, struct au_dykey, dk_rcu); | |
116 | DyPrSym(key); | |
117 | kfree(key); | |
118 | } | |
119 | ||
120 | static void dy_free(struct kref *kref) | |
121 | { | |
122 | struct au_dykey *key; | |
123 | struct au_sphlhead *sphl; | |
124 | ||
125 | key = container_of(kref, struct au_dykey, dk_kref); | |
126 | sphl = dynop + key->dk_op.dy_type; | |
127 | au_sphl_del_rcu(&key->dk_hnode, sphl); | |
128 | call_rcu(&key->dk_rcu, dy_free_rcu); | |
129 | } | |
130 | ||
131 | void au_dy_put(struct au_dykey *key) | |
132 | { | |
133 | kref_put(&key->dk_kref, dy_free); | |
134 | } | |
135 | ||
136 | /* ---------------------------------------------------------------------- */ | |
137 | ||
138 | #define DyDbgSize(cnt, op) AuDebugOn(cnt != sizeof(op)/sizeof(void *)) | |
139 | ||
140 | #ifdef CONFIG_AUFS_DEBUG | |
141 | #define DyDbgDeclare(cnt) unsigned int cnt = 0 | |
142 | #define DyDbgInc(cnt) do { cnt++; } while (0) | |
143 | #else | |
144 | #define DyDbgDeclare(cnt) do {} while (0) | |
145 | #define DyDbgInc(cnt) do {} while (0) | |
146 | #endif | |
147 | ||
148 | #define DySet(func, dst, src, h_op, h_sb) do { \ | |
149 | DyDbgInc(cnt); \ | |
150 | if (h_op->func) { \ | |
151 | if (src.func) \ | |
152 | dst.func = src.func; \ | |
153 | else \ | |
154 | AuDbg("%s %s\n", au_sbtype(h_sb), #func); \ | |
155 | } \ | |
156 | } while (0) | |
157 | ||
158 | #define DySetForce(func, dst, src) do { \ | |
159 | AuDebugOn(!src.func); \ | |
160 | DyDbgInc(cnt); \ | |
161 | dst.func = src.func; \ | |
162 | } while (0) | |
163 | ||
164 | #define DySetAop(func) \ | |
165 | DySet(func, dyaop->da_op, aufs_aop, h_aop, h_sb) | |
166 | #define DySetAopForce(func) \ | |
167 | DySetForce(func, dyaop->da_op, aufs_aop) | |
168 | ||
169 | static void dy_aop(struct au_dykey *key, const void *h_op, | |
170 | struct super_block *h_sb __maybe_unused) | |
171 | { | |
172 | struct au_dyaop *dyaop = (void *)key; | |
173 | const struct address_space_operations *h_aop = h_op; | |
174 | DyDbgDeclare(cnt); | |
175 | ||
176 | AuDbg("%s\n", au_sbtype(h_sb)); | |
177 | ||
178 | DySetAop(writepage); | |
179 | DySetAopForce(readpage); /* force */ | |
180 | DySetAop(writepages); | |
181 | DySetAop(set_page_dirty); | |
182 | DySetAop(readpages); | |
183 | DySetAop(write_begin); | |
184 | DySetAop(write_end); | |
185 | DySetAop(bmap); | |
186 | DySetAop(invalidatepage); | |
187 | DySetAop(releasepage); | |
188 | DySetAop(freepage); | |
189 | /* this one will be changed according to an aufs mount option */ | |
190 | DySetAop(direct_IO); | |
191 | DySetAop(migratepage); | |
192 | DySetAop(isolate_page); | |
193 | DySetAop(putback_page); | |
194 | DySetAop(launder_page); | |
195 | DySetAop(is_partially_uptodate); | |
196 | DySetAop(is_dirty_writeback); | |
197 | DySetAop(error_remove_page); | |
198 | DySetAop(swap_activate); | |
199 | DySetAop(swap_deactivate); | |
200 | ||
201 | DyDbgSize(cnt, *h_aop); | |
202 | } | |
203 | ||
204 | /* ---------------------------------------------------------------------- */ | |
205 | ||
206 | static void dy_bug(struct kref *kref) | |
207 | { | |
208 | BUG(); | |
209 | } | |
210 | ||
211 | static struct au_dykey *dy_get(struct au_dynop *op, struct au_branch *br) | |
212 | { | |
213 | struct au_dykey *key, *old; | |
214 | struct au_sphlhead *sphl; | |
215 | struct op { | |
216 | unsigned int sz; | |
217 | void (*set)(struct au_dykey *key, const void *h_op, | |
218 | struct super_block *h_sb __maybe_unused); | |
219 | }; | |
220 | static const struct op a[] = { | |
221 | [AuDy_AOP] = { | |
222 | .sz = sizeof(struct au_dyaop), | |
223 | .set = dy_aop | |
224 | } | |
225 | }; | |
226 | const struct op *p; | |
227 | ||
228 | sphl = dynop + op->dy_type; | |
229 | key = dy_gfind_get(sphl, op->dy_hop); | |
230 | if (key) | |
231 | goto out_add; /* success */ | |
232 | ||
233 | p = a + op->dy_type; | |
234 | key = kzalloc(p->sz, GFP_NOFS); | |
235 | if (unlikely(!key)) { | |
236 | key = ERR_PTR(-ENOMEM); | |
237 | goto out; | |
238 | } | |
239 | ||
240 | key->dk_op.dy_hop = op->dy_hop; | |
241 | kref_init(&key->dk_kref); | |
242 | p->set(key, op->dy_hop, au_br_sb(br)); | |
243 | old = dy_gadd(sphl, key); | |
244 | if (old) { | |
245 | kfree(key); | |
246 | key = old; | |
247 | } | |
248 | ||
249 | out_add: | |
250 | old = dy_bradd(br, key); | |
251 | if (old) | |
252 | /* its ref-count should never be zero here */ | |
253 | kref_put(&key->dk_kref, dy_bug); | |
254 | out: | |
255 | return key; | |
256 | } | |
257 | ||
258 | /* ---------------------------------------------------------------------- */ | |
259 | /* | |
260 | * Aufs prohibits O_DIRECT by defaut even if the branch supports it. | |
261 | * This behaviour is necessary to return an error from open(O_DIRECT) instead | |
262 | * of the succeeding I/O. The dio mount option enables O_DIRECT and makes | |
263 | * open(O_DIRECT) always succeed, but the succeeding I/O may return an error. | |
264 | * See the aufs manual in detail. | |
265 | */ | |
266 | static void dy_adx(struct au_dyaop *dyaop, int do_dx) | |
267 | { | |
268 | if (!do_dx) | |
269 | dyaop->da_op.direct_IO = NULL; | |
270 | else | |
271 | dyaop->da_op.direct_IO = aufs_aop.direct_IO; | |
272 | } | |
273 | ||
274 | static struct au_dyaop *dy_aget(struct au_branch *br, | |
275 | const struct address_space_operations *h_aop, | |
276 | int do_dx) | |
277 | { | |
278 | struct au_dyaop *dyaop; | |
279 | struct au_dynop op; | |
280 | ||
281 | op.dy_type = AuDy_AOP; | |
282 | op.dy_haop = h_aop; | |
283 | dyaop = (void *)dy_get(&op, br); | |
284 | if (IS_ERR(dyaop)) | |
285 | goto out; | |
286 | dy_adx(dyaop, do_dx); | |
287 | ||
288 | out: | |
289 | return dyaop; | |
290 | } | |
291 | ||
292 | int au_dy_iaop(struct inode *inode, aufs_bindex_t bindex, | |
293 | struct inode *h_inode) | |
294 | { | |
295 | int err, do_dx; | |
296 | struct super_block *sb; | |
297 | struct au_branch *br; | |
298 | struct au_dyaop *dyaop; | |
299 | ||
300 | AuDebugOn(!S_ISREG(h_inode->i_mode)); | |
301 | IiMustWriteLock(inode); | |
302 | ||
303 | sb = inode->i_sb; | |
304 | br = au_sbr(sb, bindex); | |
305 | do_dx = !!au_opt_test(au_mntflags(sb), DIO); | |
306 | dyaop = dy_aget(br, h_inode->i_mapping->a_ops, do_dx); | |
307 | err = PTR_ERR(dyaop); | |
308 | if (IS_ERR(dyaop)) | |
309 | /* unnecessary to call dy_fput() */ | |
310 | goto out; | |
311 | ||
312 | err = 0; | |
313 | inode->i_mapping->a_ops = &dyaop->da_op; | |
314 | ||
315 | out: | |
316 | return err; | |
317 | } | |
318 | ||
319 | /* | |
320 | * Is it safe to replace a_ops during the inode/file is in operation? | |
321 | * Yes, I hope so. | |
322 | */ | |
323 | int au_dy_irefresh(struct inode *inode) | |
324 | { | |
325 | int err; | |
326 | aufs_bindex_t btop; | |
327 | struct inode *h_inode; | |
328 | ||
329 | err = 0; | |
330 | if (S_ISREG(inode->i_mode)) { | |
331 | btop = au_ibtop(inode); | |
332 | h_inode = au_h_iptr(inode, btop); | |
333 | err = au_dy_iaop(inode, btop, h_inode); | |
334 | } | |
335 | return err; | |
336 | } | |
337 | ||
338 | void au_dy_arefresh(int do_dx) | |
339 | { | |
340 | struct au_sphlhead *sphl; | |
341 | struct hlist_head *head; | |
342 | struct au_dykey *key; | |
343 | ||
344 | sphl = dynop + AuDy_AOP; | |
345 | head = &sphl->head; | |
346 | spin_lock(&sphl->spin); | |
347 | hlist_for_each_entry(key, head, dk_hnode) | |
348 | dy_adx((void *)key, do_dx); | |
349 | spin_unlock(&sphl->spin); | |
350 | } | |
351 | ||
352 | /* ---------------------------------------------------------------------- */ | |
353 | ||
354 | void __init au_dy_init(void) | |
355 | { | |
356 | int i; | |
357 | ||
358 | /* make sure that 'struct au_dykey *' can be any type */ | |
359 | BUILD_BUG_ON(offsetof(struct au_dyaop, da_key)); | |
360 | ||
361 | for (i = 0; i < AuDyLast; i++) | |
362 | au_sphl_init(dynop + i); | |
363 | } | |
364 | ||
365 | void au_dy_fin(void) | |
366 | { | |
367 | int i; | |
368 | ||
369 | for (i = 0; i < AuDyLast; i++) | |
370 | WARN_ON(!hlist_empty(&dynop[i].head)); | |
371 | } |