/* * fs/ioprio.c * * Copyright (C) 2004 Jens Axboe <axboe@suse.de> * * Helper functions for setting/querying io priorities of processes. The * system calls closely mimmick getpriority/setpriority, see the man page for * those. The prio argument is a composite of prio class and prio data, where * the data argument has meaning within that class. The standard scheduling * classes have 8 distinct prio levels, with 0 being the highest prio and 7 * being the lowest. * * IOW, setting BE scheduling class with prio 2 is done ala: * * unsigned int prio = (IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT) | 2; * * ioprio_set(PRIO_PROCESS, pid, prio); * * See also Documentation/block/ioprio.txt * */#include <linux/kernel.h>#include <linux/ioprio.h>#include <linux/blkdev.h>#include <linux/vs_cvirt.h>static int set_task_ioprio(struct task_struct *task, int ioprio){ struct io_context *ioc; if (task->uid != current->euid && task->uid != current->uid && !capable(CAP_SYS_NICE)) return -EPERM; task_lock(task); task->ioprio = ioprio; ioc = task->io_context; if (ioc && ioc->set_ioprio) ioc->set_ioprio(ioc, ioprio); task_unlock(task); return 0;}asmlinkage long sys_ioprio_set(int which, int who, int ioprio){ int class = IOPRIO_PRIO_CLASS(ioprio); int data = IOPRIO_PRIO_DATA(ioprio); struct task_struct *p, *g; struct user_struct *user; int ret; pid_t pid; if (!pid) pid = vx_map_pid(current->pid); switch (class) { case IOPRIO_CLASS_RT: if (!capable(CAP_SYS_ADMIN)) return -EPERM; /* fall through, rt has prio field too */ case IOPRIO_CLASS_BE: if (data >= IOPRIO_BE_NR || data < 0) return -EINVAL; break; case IOPRIO_CLASS_IDLE: break; default: return -EINVAL; } ret = -ESRCH; read_lock_irq(&tasklist_lock); switch (which) { case IOPRIO_WHO_PROCESS: if (!who) p = current; else p = find_task_by_pid(who); if (p) ret = set_task_ioprio(p, ioprio); break; case IOPRIO_WHO_PGRP: if (!who) who = process_group(current); do_each_task_pid(who, PIDTYPE_PGID, p) { ret = set_task_ioprio(p, ioprio); if (ret) break; } while_each_task_pid(who, PIDTYPE_PGID, p); break; case IOPRIO_WHO_USER: if (!who) user = current->user; else user = find_user(who); if (!user) break; do_each_thread(g, p) { if (p->uid != who) continue; ret = set_task_ioprio(p, ioprio); if (ret) break; } while_each_thread(g, p); if (who) free_uid(user); break; default: ret = -EINVAL; } read_unlock_irq(&tasklist_lock); return ret;}asmlinkage long sys_ioprio_get(int which, int who){ struct task_struct *g, *p; struct user_struct *user; int ret = -ESRCH; read_lock_irq(&tasklist_lock); switch (which) { case IOPRIO_WHO_PROCESS: if (!who) p = current; else p = find_task_by_pid(who); if (p) ret = p->ioprio; break; case IOPRIO_WHO_PGRP: if (!who) who = process_group(current); do_each_task_pid(who, PIDTYPE_PGID, p) { if (ret == -ESRCH) ret = p->ioprio; else ret = ioprio_best(ret, p->ioprio); } while_each_task_pid(who, PIDTYPE_PGID, p); break; case IOPRIO_WHO_USER: if (!who) user = current->user; else user = find_user(who); if (!user) break; do_each_thread(g, p) { if (p->uid != user->uid) continue; if (ret == -ESRCH) ret = p->ioprio; else ret = ioprio_best(ret, p->ioprio); } while_each_thread(g, p); if (who) free_uid(user); break; default: ret = -EINVAL; } read_unlock_irq(&tasklist_lock); return ret;}