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f719ff9bce
But first update the code that uses these facilities with the new header. Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
250 lines
5.2 KiB
C
250 lines
5.2 KiB
C
/*
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* fs/ioprio.c
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*
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* Copyright (C) 2004 Jens Axboe <axboe@kernel.dk>
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*
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* Helper functions for setting/querying io priorities of processes. The
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* system calls closely mimmick getpriority/setpriority, see the man page for
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* those. The prio argument is a composite of prio class and prio data, where
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* the data argument has meaning within that class. The standard scheduling
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* classes have 8 distinct prio levels, with 0 being the highest prio and 7
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* being the lowest.
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*
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* IOW, setting BE scheduling class with prio 2 is done ala:
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*
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* unsigned int prio = (IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT) | 2;
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*
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* ioprio_set(PRIO_PROCESS, pid, prio);
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*
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* See also Documentation/block/ioprio.txt
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*
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*/
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#include <linux/gfp.h>
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/ioprio.h>
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#include <linux/cred.h>
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#include <linux/blkdev.h>
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#include <linux/capability.h>
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#include <linux/sched/user.h>
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#include <linux/sched/task.h>
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#include <linux/syscalls.h>
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#include <linux/security.h>
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#include <linux/pid_namespace.h>
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int set_task_ioprio(struct task_struct *task, int ioprio)
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{
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int err;
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struct io_context *ioc;
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const struct cred *cred = current_cred(), *tcred;
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rcu_read_lock();
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tcred = __task_cred(task);
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if (!uid_eq(tcred->uid, cred->euid) &&
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!uid_eq(tcred->uid, cred->uid) && !capable(CAP_SYS_NICE)) {
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rcu_read_unlock();
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return -EPERM;
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}
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rcu_read_unlock();
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err = security_task_setioprio(task, ioprio);
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if (err)
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return err;
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ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE);
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if (ioc) {
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ioc->ioprio = ioprio;
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put_io_context(ioc);
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}
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return err;
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}
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EXPORT_SYMBOL_GPL(set_task_ioprio);
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SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
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{
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int class = IOPRIO_PRIO_CLASS(ioprio);
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int data = IOPRIO_PRIO_DATA(ioprio);
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struct task_struct *p, *g;
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struct user_struct *user;
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struct pid *pgrp;
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kuid_t uid;
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int ret;
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switch (class) {
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case IOPRIO_CLASS_RT:
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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/* fall through, rt has prio field too */
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case IOPRIO_CLASS_BE:
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if (data >= IOPRIO_BE_NR || data < 0)
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return -EINVAL;
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break;
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case IOPRIO_CLASS_IDLE:
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break;
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case IOPRIO_CLASS_NONE:
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if (data)
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return -EINVAL;
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break;
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default:
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return -EINVAL;
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}
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ret = -ESRCH;
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rcu_read_lock();
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switch (which) {
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case IOPRIO_WHO_PROCESS:
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if (!who)
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p = current;
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else
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p = find_task_by_vpid(who);
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if (p)
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ret = set_task_ioprio(p, ioprio);
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break;
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case IOPRIO_WHO_PGRP:
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if (!who)
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pgrp = task_pgrp(current);
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else
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pgrp = find_vpid(who);
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do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
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ret = set_task_ioprio(p, ioprio);
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if (ret)
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break;
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} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
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break;
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case IOPRIO_WHO_USER:
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uid = make_kuid(current_user_ns(), who);
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if (!uid_valid(uid))
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break;
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if (!who)
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user = current_user();
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else
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user = find_user(uid);
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if (!user)
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break;
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for_each_process_thread(g, p) {
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if (!uid_eq(task_uid(p), uid) ||
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!task_pid_vnr(p))
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continue;
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ret = set_task_ioprio(p, ioprio);
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if (ret)
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goto free_uid;
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}
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free_uid:
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if (who)
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free_uid(user);
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break;
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default:
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ret = -EINVAL;
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}
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rcu_read_unlock();
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return ret;
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}
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static int get_task_ioprio(struct task_struct *p)
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{
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int ret;
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ret = security_task_getioprio(p);
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if (ret)
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goto out;
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ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
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task_lock(p);
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if (p->io_context)
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ret = p->io_context->ioprio;
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task_unlock(p);
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out:
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return ret;
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}
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int ioprio_best(unsigned short aprio, unsigned short bprio)
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{
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unsigned short aclass;
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unsigned short bclass;
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if (!ioprio_valid(aprio))
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aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
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if (!ioprio_valid(bprio))
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bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
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aclass = IOPRIO_PRIO_CLASS(aprio);
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bclass = IOPRIO_PRIO_CLASS(bprio);
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if (aclass == bclass)
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return min(aprio, bprio);
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if (aclass > bclass)
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return bprio;
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else
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return aprio;
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}
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SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
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{
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struct task_struct *g, *p;
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struct user_struct *user;
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struct pid *pgrp;
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kuid_t uid;
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int ret = -ESRCH;
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int tmpio;
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rcu_read_lock();
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switch (which) {
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case IOPRIO_WHO_PROCESS:
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if (!who)
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p = current;
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else
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p = find_task_by_vpid(who);
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if (p)
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ret = get_task_ioprio(p);
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break;
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case IOPRIO_WHO_PGRP:
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if (!who)
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pgrp = task_pgrp(current);
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else
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pgrp = find_vpid(who);
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do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
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tmpio = get_task_ioprio(p);
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if (tmpio < 0)
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continue;
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if (ret == -ESRCH)
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ret = tmpio;
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else
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ret = ioprio_best(ret, tmpio);
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} while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
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break;
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case IOPRIO_WHO_USER:
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uid = make_kuid(current_user_ns(), who);
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if (!who)
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user = current_user();
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else
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user = find_user(uid);
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if (!user)
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break;
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for_each_process_thread(g, p) {
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if (!uid_eq(task_uid(p), user->uid) ||
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!task_pid_vnr(p))
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continue;
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tmpio = get_task_ioprio(p);
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if (tmpio < 0)
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continue;
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if (ret == -ESRCH)
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ret = tmpio;
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else
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ret = ioprio_best(ret, tmpio);
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}
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if (who)
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free_uid(user);
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break;
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default:
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ret = -EINVAL;
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}
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rcu_read_unlock();
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return ret;
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}
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