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git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - fs/ioprio.c
4 * Copyright (C) 2004 Jens Axboe <axboe@kernel.dk>
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
13 * IOW, setting BE scheduling class with prio 2 is done ala:
15 * unsigned int prio = (IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT) | 2;
17 * ioprio_set(PRIO_PROCESS, pid, prio);
19 * See also Documentation/block/ioprio.txt
22 #include <linux/gfp.h>
23 #include <linux/kernel.h>
24 #include <linux/ioprio.h>
25 #include <linux/blkdev.h>
26 #include <linux/capability.h>
27 #include <linux/syscalls.h>
28 #include <linux/security.h>
29 #include <linux/pid_namespace.h>
31 int set_task_ioprio(struct task_struct
*task
, int ioprio
)
34 struct io_context
*ioc
;
35 const struct cred
*cred
= current_cred(), *tcred
;
38 tcred
= __task_cred(task
);
39 if (tcred
->uid
!= cred
->euid
&&
40 tcred
->uid
!= cred
->uid
&& !capable(CAP_SYS_NICE
)) {
46 err
= security_task_setioprio(task
, ioprio
);
52 ioc
= task
->io_context
;
53 /* see wmb() in current_io_context() */
54 smp_read_barrier_depends();
58 ioc
= alloc_io_context(GFP_ATOMIC
, -1);
63 task
->io_context
= ioc
;
68 ioc
->ioprio_changed
= 1;
74 EXPORT_SYMBOL_GPL(set_task_ioprio
);
76 SYSCALL_DEFINE3(ioprio_set
, int, which
, int, who
, int, ioprio
)
78 int class = IOPRIO_PRIO_CLASS(ioprio
);
79 int data
= IOPRIO_PRIO_DATA(ioprio
);
80 struct task_struct
*p
, *g
;
81 struct user_struct
*user
;
87 if (!capable(CAP_SYS_ADMIN
))
89 /* fall through, rt has prio field too */
91 if (data
>= IOPRIO_BE_NR
|| data
< 0)
95 case IOPRIO_CLASS_IDLE
:
97 case IOPRIO_CLASS_NONE
:
108 case IOPRIO_WHO_PROCESS
:
112 p
= find_task_by_vpid(who
);
114 ret
= set_task_ioprio(p
, ioprio
);
116 case IOPRIO_WHO_PGRP
:
118 pgrp
= task_pgrp(current
);
120 pgrp
= find_vpid(who
);
121 do_each_pid_thread(pgrp
, PIDTYPE_PGID
, p
) {
122 ret
= set_task_ioprio(p
, ioprio
);
125 } while_each_pid_thread(pgrp
, PIDTYPE_PGID
, p
);
127 case IOPRIO_WHO_USER
:
129 user
= current_user();
131 user
= find_user(who
);
136 do_each_thread(g
, p
) {
137 if (__task_cred(p
)->uid
!= who
)
139 ret
= set_task_ioprio(p
, ioprio
);
142 } while_each_thread(g
, p
);
155 static int get_task_ioprio(struct task_struct
*p
)
159 ret
= security_task_getioprio(p
);
162 ret
= IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE
, IOPRIO_NORM
);
164 ret
= p
->io_context
->ioprio
;
169 int ioprio_best(unsigned short aprio
, unsigned short bprio
)
171 unsigned short aclass
= IOPRIO_PRIO_CLASS(aprio
);
172 unsigned short bclass
= IOPRIO_PRIO_CLASS(bprio
);
174 if (aclass
== IOPRIO_CLASS_NONE
)
175 aclass
= IOPRIO_CLASS_BE
;
176 if (bclass
== IOPRIO_CLASS_NONE
)
177 bclass
= IOPRIO_CLASS_BE
;
179 if (aclass
== bclass
)
180 return min(aprio
, bprio
);
187 SYSCALL_DEFINE2(ioprio_get
, int, which
, int, who
)
189 struct task_struct
*g
, *p
;
190 struct user_struct
*user
;
197 case IOPRIO_WHO_PROCESS
:
201 p
= find_task_by_vpid(who
);
203 ret
= get_task_ioprio(p
);
205 case IOPRIO_WHO_PGRP
:
207 pgrp
= task_pgrp(current
);
209 pgrp
= find_vpid(who
);
210 do_each_pid_thread(pgrp
, PIDTYPE_PGID
, p
) {
211 tmpio
= get_task_ioprio(p
);
217 ret
= ioprio_best(ret
, tmpio
);
218 } while_each_pid_thread(pgrp
, PIDTYPE_PGID
, p
);
220 case IOPRIO_WHO_USER
:
222 user
= current_user();
224 user
= find_user(who
);
229 do_each_thread(g
, p
) {
230 if (__task_cred(p
)->uid
!= user
->uid
)
232 tmpio
= get_task_ioprio(p
);
238 ret
= ioprio_best(ret
, tmpio
);
239 } while_each_thread(g
, p
);