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5b88fdd9 SF |
1 | /* |
2 | * Copyright (C) 2005-2016 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 | * workqueue for asynchronous/super-io operations | |
20 | * todo: try new dredential scheme | |
21 | */ | |
22 | ||
23 | #include <linux/module.h> | |
24 | #include "aufs.h" | |
25 | ||
26 | /* internal workqueue named AUFS_WKQ_NAME */ | |
27 | ||
28 | static struct workqueue_struct *au_wkq; | |
29 | ||
30 | struct au_wkinfo { | |
31 | struct work_struct wk; | |
32 | struct kobject *kobj; | |
33 | ||
34 | unsigned int flags; /* see wkq.h */ | |
35 | ||
36 | au_wkq_func_t func; | |
37 | void *args; | |
38 | ||
39 | struct completion *comp; | |
40 | }; | |
41 | ||
42 | /* ---------------------------------------------------------------------- */ | |
43 | ||
44 | static void wkq_func(struct work_struct *wk) | |
45 | { | |
46 | struct au_wkinfo *wkinfo = container_of(wk, struct au_wkinfo, wk); | |
47 | ||
48 | AuDebugOn(!uid_eq(current_fsuid(), GLOBAL_ROOT_UID)); | |
49 | AuDebugOn(rlimit(RLIMIT_FSIZE) != RLIM_INFINITY); | |
50 | ||
51 | wkinfo->func(wkinfo->args); | |
52 | if (au_ftest_wkq(wkinfo->flags, WAIT)) | |
53 | complete(wkinfo->comp); | |
54 | else { | |
55 | kobject_put(wkinfo->kobj); | |
56 | module_put(THIS_MODULE); /* todo: ?? */ | |
57 | au_delayed_kfree(wkinfo); | |
58 | } | |
59 | } | |
60 | ||
61 | /* | |
62 | * Since struct completion is large, try allocating it dynamically. | |
63 | */ | |
64 | #if 1 /* defined(CONFIG_4KSTACKS) || defined(AuTest4KSTACKS) */ | |
65 | #define AuWkqCompDeclare(name) struct completion *comp = NULL | |
66 | ||
67 | static int au_wkq_comp_alloc(struct au_wkinfo *wkinfo, struct completion **comp) | |
68 | { | |
69 | *comp = kmalloc(sizeof(**comp), GFP_NOFS); | |
70 | if (*comp) { | |
71 | init_completion(*comp); | |
72 | wkinfo->comp = *comp; | |
73 | return 0; | |
74 | } | |
75 | return -ENOMEM; | |
76 | } | |
77 | ||
78 | static void au_wkq_comp_free(struct completion *comp) | |
79 | { | |
80 | au_delayed_kfree(comp); | |
81 | } | |
82 | ||
83 | #else | |
84 | ||
85 | /* no braces */ | |
86 | #define AuWkqCompDeclare(name) \ | |
87 | DECLARE_COMPLETION_ONSTACK(_ ## name); \ | |
88 | struct completion *comp = &_ ## name | |
89 | ||
90 | static int au_wkq_comp_alloc(struct au_wkinfo *wkinfo, struct completion **comp) | |
91 | { | |
92 | wkinfo->comp = *comp; | |
93 | return 0; | |
94 | } | |
95 | ||
96 | static void au_wkq_comp_free(struct completion *comp __maybe_unused) | |
97 | { | |
98 | /* empty */ | |
99 | } | |
100 | #endif /* 4KSTACKS */ | |
101 | ||
102 | static void au_wkq_run(struct au_wkinfo *wkinfo) | |
103 | { | |
104 | if (au_ftest_wkq(wkinfo->flags, NEST)) { | |
105 | if (au_wkq_test()) { | |
106 | AuWarn1("wkq from wkq, unless silly-rename on NFS," | |
107 | " due to a dead dir by UDBA?\n"); | |
108 | AuDebugOn(au_ftest_wkq(wkinfo->flags, WAIT)); | |
109 | } | |
110 | } else | |
111 | au_dbg_verify_kthread(); | |
112 | ||
113 | if (au_ftest_wkq(wkinfo->flags, WAIT)) { | |
114 | INIT_WORK_ONSTACK(&wkinfo->wk, wkq_func); | |
115 | queue_work(au_wkq, &wkinfo->wk); | |
116 | } else { | |
117 | INIT_WORK(&wkinfo->wk, wkq_func); | |
118 | schedule_work(&wkinfo->wk); | |
119 | } | |
120 | } | |
121 | ||
122 | /* | |
123 | * Be careful. It is easy to make deadlock happen. | |
124 | * processA: lock, wkq and wait | |
125 | * processB: wkq and wait, lock in wkq | |
126 | * --> deadlock | |
127 | */ | |
128 | int au_wkq_do_wait(unsigned int flags, au_wkq_func_t func, void *args) | |
129 | { | |
130 | int err; | |
131 | AuWkqCompDeclare(comp); | |
132 | struct au_wkinfo wkinfo = { | |
133 | .flags = flags, | |
134 | .func = func, | |
135 | .args = args | |
136 | }; | |
137 | ||
138 | err = au_wkq_comp_alloc(&wkinfo, &comp); | |
139 | if (!err) { | |
140 | au_wkq_run(&wkinfo); | |
141 | /* no timeout, no interrupt */ | |
142 | wait_for_completion(wkinfo.comp); | |
143 | au_wkq_comp_free(comp); | |
144 | destroy_work_on_stack(&wkinfo.wk); | |
145 | } | |
146 | ||
147 | return err; | |
148 | ||
149 | } | |
150 | ||
151 | /* | |
152 | * Note: dget/dput() in func for aufs dentries are not supported. It will be a | |
153 | * problem in a concurrent umounting. | |
154 | */ | |
155 | int au_wkq_nowait(au_wkq_func_t func, void *args, struct super_block *sb, | |
156 | unsigned int flags) | |
157 | { | |
158 | int err; | |
159 | struct au_wkinfo *wkinfo; | |
160 | ||
161 | atomic_inc(&au_sbi(sb)->si_nowait.nw_len); | |
162 | ||
163 | /* | |
164 | * wkq_func() must free this wkinfo. | |
165 | * it highly depends upon the implementation of workqueue. | |
166 | */ | |
167 | err = 0; | |
168 | wkinfo = kmalloc(sizeof(*wkinfo), GFP_NOFS); | |
169 | if (wkinfo) { | |
170 | wkinfo->kobj = &au_sbi(sb)->si_kobj; | |
171 | wkinfo->flags = flags & ~AuWkq_WAIT; | |
172 | wkinfo->func = func; | |
173 | wkinfo->args = args; | |
174 | wkinfo->comp = NULL; | |
175 | kobject_get(wkinfo->kobj); | |
176 | __module_get(THIS_MODULE); /* todo: ?? */ | |
177 | ||
178 | au_wkq_run(wkinfo); | |
179 | } else { | |
180 | err = -ENOMEM; | |
181 | au_nwt_done(&au_sbi(sb)->si_nowait); | |
182 | } | |
183 | ||
184 | return err; | |
185 | } | |
186 | ||
187 | /* ---------------------------------------------------------------------- */ | |
188 | ||
189 | void au_nwt_init(struct au_nowait_tasks *nwt) | |
190 | { | |
191 | atomic_set(&nwt->nw_len, 0); | |
192 | /* smp_mb(); */ /* atomic_set */ | |
193 | init_waitqueue_head(&nwt->nw_wq); | |
194 | } | |
195 | ||
196 | void au_wkq_fin(void) | |
197 | { | |
198 | destroy_workqueue(au_wkq); | |
199 | } | |
200 | ||
201 | int __init au_wkq_init(void) | |
202 | { | |
203 | int err; | |
204 | ||
205 | err = 0; | |
206 | au_wkq = alloc_workqueue(AUFS_WKQ_NAME, 0, WQ_DFL_ACTIVE); | |
207 | if (IS_ERR(au_wkq)) | |
208 | err = PTR_ERR(au_wkq); | |
209 | else if (!au_wkq) | |
210 | err = -ENOMEM; | |
211 | ||
212 | return err; | |
213 | } |