mtd: spi-nor: Add an SPDX tag to spi-nor.{c,h}
[linux-2.6-microblaze.git] / block / ioprio.c
1 /*
2  * fs/ioprio.c
3  *
4  * Copyright (C) 2004 Jens Axboe <axboe@kernel.dk>
5  *
6  * Helper functions for setting/querying io priorities of processes. The
7  * system calls closely mimmick getpriority/setpriority, see the man page for
8  * those. The prio argument is a composite of prio class and prio data, where
9  * the data argument has meaning within that class. The standard scheduling
10  * classes have 8 distinct prio levels, with 0 being the highest prio and 7
11  * being the lowest.
12  *
13  * IOW, setting BE scheduling class with prio 2 is done ala:
14  *
15  * unsigned int prio = (IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT) | 2;
16  *
17  * ioprio_set(PRIO_PROCESS, pid, prio);
18  *
19  * See also Documentation/block/ioprio.txt
20  *
21  */
22 #include <linux/gfp.h>
23 #include <linux/kernel.h>
24 #include <linux/export.h>
25 #include <linux/ioprio.h>
26 #include <linux/cred.h>
27 #include <linux/blkdev.h>
28 #include <linux/capability.h>
29 #include <linux/sched/user.h>
30 #include <linux/sched/task.h>
31 #include <linux/syscalls.h>
32 #include <linux/security.h>
33 #include <linux/pid_namespace.h>
34
35 int set_task_ioprio(struct task_struct *task, int ioprio)
36 {
37         int err;
38         struct io_context *ioc;
39         const struct cred *cred = current_cred(), *tcred;
40
41         rcu_read_lock();
42         tcred = __task_cred(task);
43         if (!uid_eq(tcred->uid, cred->euid) &&
44             !uid_eq(tcred->uid, cred->uid) && !capable(CAP_SYS_NICE)) {
45                 rcu_read_unlock();
46                 return -EPERM;
47         }
48         rcu_read_unlock();
49
50         err = security_task_setioprio(task, ioprio);
51         if (err)
52                 return err;
53
54         ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE);
55         if (ioc) {
56                 ioc->ioprio = ioprio;
57                 put_io_context(ioc);
58         }
59
60         return err;
61 }
62 EXPORT_SYMBOL_GPL(set_task_ioprio);
63
64 int ioprio_check_cap(int ioprio)
65 {
66         int class = IOPRIO_PRIO_CLASS(ioprio);
67         int data = IOPRIO_PRIO_DATA(ioprio);
68
69         switch (class) {
70                 case IOPRIO_CLASS_RT:
71                         if (!capable(CAP_SYS_ADMIN))
72                                 return -EPERM;
73                         /* fall through */
74                         /* rt has prio field too */
75                 case IOPRIO_CLASS_BE:
76                         if (data >= IOPRIO_BE_NR || data < 0)
77                                 return -EINVAL;
78
79                         break;
80                 case IOPRIO_CLASS_IDLE:
81                         break;
82                 case IOPRIO_CLASS_NONE:
83                         if (data)
84                                 return -EINVAL;
85                         break;
86                 default:
87                         return -EINVAL;
88         }
89
90         return 0;
91 }
92
93 SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
94 {
95         struct task_struct *p, *g;
96         struct user_struct *user;
97         struct pid *pgrp;
98         kuid_t uid;
99         int ret;
100
101         ret = ioprio_check_cap(ioprio);
102         if (ret)
103                 return ret;
104
105         ret = -ESRCH;
106         rcu_read_lock();
107         switch (which) {
108                 case IOPRIO_WHO_PROCESS:
109                         if (!who)
110                                 p = current;
111                         else
112                                 p = find_task_by_vpid(who);
113                         if (p)
114                                 ret = set_task_ioprio(p, ioprio);
115                         break;
116                 case IOPRIO_WHO_PGRP:
117                         if (!who)
118                                 pgrp = task_pgrp(current);
119                         else
120                                 pgrp = find_vpid(who);
121                         do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
122                                 ret = set_task_ioprio(p, ioprio);
123                                 if (ret)
124                                         break;
125                         } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
126                         break;
127                 case IOPRIO_WHO_USER:
128                         uid = make_kuid(current_user_ns(), who);
129                         if (!uid_valid(uid))
130                                 break;
131                         if (!who)
132                                 user = current_user();
133                         else
134                                 user = find_user(uid);
135
136                         if (!user)
137                                 break;
138
139                         for_each_process_thread(g, p) {
140                                 if (!uid_eq(task_uid(p), uid) ||
141                                     !task_pid_vnr(p))
142                                         continue;
143                                 ret = set_task_ioprio(p, ioprio);
144                                 if (ret)
145                                         goto free_uid;
146                         }
147 free_uid:
148                         if (who)
149                                 free_uid(user);
150                         break;
151                 default:
152                         ret = -EINVAL;
153         }
154
155         rcu_read_unlock();
156         return ret;
157 }
158
159 static int get_task_ioprio(struct task_struct *p)
160 {
161         int ret;
162
163         ret = security_task_getioprio(p);
164         if (ret)
165                 goto out;
166         ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
167         task_lock(p);
168         if (p->io_context)
169                 ret = p->io_context->ioprio;
170         task_unlock(p);
171 out:
172         return ret;
173 }
174
175 int ioprio_best(unsigned short aprio, unsigned short bprio)
176 {
177         if (!ioprio_valid(aprio))
178                 aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
179         if (!ioprio_valid(bprio))
180                 bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
181
182         return min(aprio, bprio);
183 }
184
185 SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
186 {
187         struct task_struct *g, *p;
188         struct user_struct *user;
189         struct pid *pgrp;
190         kuid_t uid;
191         int ret = -ESRCH;
192         int tmpio;
193
194         rcu_read_lock();
195         switch (which) {
196                 case IOPRIO_WHO_PROCESS:
197                         if (!who)
198                                 p = current;
199                         else
200                                 p = find_task_by_vpid(who);
201                         if (p)
202                                 ret = get_task_ioprio(p);
203                         break;
204                 case IOPRIO_WHO_PGRP:
205                         if (!who)
206                                 pgrp = task_pgrp(current);
207                         else
208                                 pgrp = find_vpid(who);
209                         do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
210                                 tmpio = get_task_ioprio(p);
211                                 if (tmpio < 0)
212                                         continue;
213                                 if (ret == -ESRCH)
214                                         ret = tmpio;
215                                 else
216                                         ret = ioprio_best(ret, tmpio);
217                         } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
218                         break;
219                 case IOPRIO_WHO_USER:
220                         uid = make_kuid(current_user_ns(), who);
221                         if (!who)
222                                 user = current_user();
223                         else
224                                 user = find_user(uid);
225
226                         if (!user)
227                                 break;
228
229                         for_each_process_thread(g, p) {
230                                 if (!uid_eq(task_uid(p), user->uid) ||
231                                     !task_pid_vnr(p))
232                                         continue;
233                                 tmpio = get_task_ioprio(p);
234                                 if (tmpio < 0)
235                                         continue;
236                                 if (ret == -ESRCH)
237                                         ret = tmpio;
238                                 else
239                                         ret = ioprio_best(ret, tmpio);
240                         }
241
242                         if (who)
243                                 free_uid(user);
244                         break;
245                 default:
246                         ret = -EINVAL;
247         }
248
249         rcu_read_unlock();
250         return ret;
251 }