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git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - fs/ioprio.c
4 * Copyright (C) 2004 Jens Axboe <axboe@suse.de>
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/kernel.h>
23 #include <linux/ioprio.h>
24 #include <linux/blkdev.h>
25 #include <linux/capability.h>
26 #include <linux/syscalls.h>
27 #include <linux/security.h>
29 static int set_task_ioprio(struct task_struct
*task
, int ioprio
)
32 struct io_context
*ioc
;
34 if (task
->uid
!= current
->euid
&&
35 task
->uid
!= current
->uid
&& !capable(CAP_SYS_NICE
))
38 err
= security_task_setioprio(task
, ioprio
);
44 task
->ioprio
= ioprio
;
46 ioc
= task
->io_context
;
47 /* see wmb() in current_io_context() */
48 smp_read_barrier_depends();
50 if (ioc
&& ioc
->set_ioprio
)
51 ioc
->set_ioprio(ioc
, ioprio
);
57 asmlinkage
long sys_ioprio_set(int which
, int who
, int ioprio
)
59 int class = IOPRIO_PRIO_CLASS(ioprio
);
60 int data
= IOPRIO_PRIO_DATA(ioprio
);
61 struct task_struct
*p
, *g
;
62 struct user_struct
*user
;
67 if (!capable(CAP_SYS_ADMIN
))
69 /* fall through, rt has prio field too */
71 if (data
>= IOPRIO_BE_NR
|| data
< 0)
75 case IOPRIO_CLASS_IDLE
:
76 if (!capable(CAP_SYS_ADMIN
))
84 read_lock_irq(&tasklist_lock
);
86 case IOPRIO_WHO_PROCESS
:
90 p
= find_task_by_pid(who
);
92 ret
= set_task_ioprio(p
, ioprio
);
96 who
= process_group(current
);
97 do_each_task_pid(who
, PIDTYPE_PGID
, p
) {
98 ret
= set_task_ioprio(p
, ioprio
);
101 } while_each_task_pid(who
, PIDTYPE_PGID
, p
);
103 case IOPRIO_WHO_USER
:
105 user
= current
->user
;
107 user
= find_user(who
);
112 do_each_thread(g
, p
) {
115 ret
= set_task_ioprio(p
, ioprio
);
118 } while_each_thread(g
, p
);
127 read_unlock_irq(&tasklist_lock
);
131 static int get_task_ioprio(struct task_struct
*p
)
135 ret
= security_task_getioprio(p
);
143 int ioprio_best(unsigned short aprio
, unsigned short bprio
)
145 unsigned short aclass
= IOPRIO_PRIO_CLASS(aprio
);
146 unsigned short bclass
= IOPRIO_PRIO_CLASS(bprio
);
148 if (!ioprio_valid(aprio
))
150 if (!ioprio_valid(bprio
))
153 if (aclass
== IOPRIO_CLASS_NONE
)
154 aclass
= IOPRIO_CLASS_BE
;
155 if (bclass
== IOPRIO_CLASS_NONE
)
156 bclass
= IOPRIO_CLASS_BE
;
158 if (aclass
== bclass
)
159 return min(aprio
, bprio
);
166 asmlinkage
long sys_ioprio_get(int which
, int who
)
168 struct task_struct
*g
, *p
;
169 struct user_struct
*user
;
173 read_lock_irq(&tasklist_lock
);
175 case IOPRIO_WHO_PROCESS
:
179 p
= find_task_by_pid(who
);
181 ret
= get_task_ioprio(p
);
183 case IOPRIO_WHO_PGRP
:
185 who
= process_group(current
);
186 do_each_task_pid(who
, PIDTYPE_PGID
, p
) {
187 tmpio
= get_task_ioprio(p
);
193 ret
= ioprio_best(ret
, tmpio
);
194 } while_each_task_pid(who
, PIDTYPE_PGID
, p
);
196 case IOPRIO_WHO_USER
:
198 user
= current
->user
;
200 user
= find_user(who
);
205 do_each_thread(g
, p
) {
206 if (p
->uid
!= user
->uid
)
208 tmpio
= get_task_ioprio(p
);
214 ret
= ioprio_best(ret
, tmpio
);
215 } while_each_thread(g
, p
);
224 read_unlock_irq(&tasklist_lock
);