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159 lines
4.4 KiB
C
159 lines
4.4 KiB
C
/*
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* JFFS2 -- Journalling Flash File System, Version 2.
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*
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* Copyright © 2001-2007 Red Hat, Inc.
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* Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
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*
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* Created by David Woodhouse <dwmw2@infradead.org>
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*
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* For licensing information, see the file 'LICENCE' in this directory.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/jffs2.h>
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#include <linux/mtd/mtd.h>
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#include <linux/completion.h>
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#include <linux/sched.h>
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#include <linux/freezer.h>
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#include <linux/kthread.h>
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#include "nodelist.h"
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static int jffs2_garbage_collect_thread(void *);
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void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
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{
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assert_spin_locked(&c->erase_completion_lock);
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if (c->gc_task && jffs2_thread_should_wake(c))
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send_sig(SIGHUP, c->gc_task, 1);
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}
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/* This must only ever be called when no GC thread is currently running */
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int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c)
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{
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struct task_struct *tsk;
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int ret = 0;
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BUG_ON(c->gc_task);
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init_completion(&c->gc_thread_start);
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init_completion(&c->gc_thread_exit);
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tsk = kthread_run(jffs2_garbage_collect_thread, c, "jffs2_gcd_mtd%d", c->mtd->index);
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if (IS_ERR(tsk)) {
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printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %ld\n", -PTR_ERR(tsk));
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complete(&c->gc_thread_exit);
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ret = PTR_ERR(tsk);
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} else {
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/* Wait for it... */
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D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", tsk->pid));
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wait_for_completion(&c->gc_thread_start);
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ret = tsk->pid;
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}
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return ret;
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}
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void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
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{
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int wait = 0;
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spin_lock(&c->erase_completion_lock);
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if (c->gc_task) {
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D1(printk(KERN_DEBUG "jffs2: Killing GC task %d\n", c->gc_task->pid));
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send_sig(SIGKILL, c->gc_task, 1);
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wait = 1;
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}
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spin_unlock(&c->erase_completion_lock);
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if (wait)
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wait_for_completion(&c->gc_thread_exit);
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}
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static int jffs2_garbage_collect_thread(void *_c)
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{
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struct jffs2_sb_info *c = _c;
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allow_signal(SIGKILL);
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allow_signal(SIGSTOP);
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allow_signal(SIGCONT);
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c->gc_task = current;
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complete(&c->gc_thread_start);
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set_user_nice(current, 10);
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set_freezable();
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for (;;) {
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allow_signal(SIGHUP);
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again:
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spin_lock(&c->erase_completion_lock);
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if (!jffs2_thread_should_wake(c)) {
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set_current_state (TASK_INTERRUPTIBLE);
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spin_unlock(&c->erase_completion_lock);
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D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n"));
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schedule();
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} else
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spin_unlock(&c->erase_completion_lock);
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/* Problem - immediately after bootup, the GCD spends a lot
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* of time in places like jffs2_kill_fragtree(); so much so
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* that userspace processes (like gdm and X) are starved
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* despite plenty of cond_resched()s and renicing. Yield()
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* doesn't help, either (presumably because userspace and GCD
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* are generally competing for a higher latency resource -
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* disk).
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* This forces the GCD to slow the hell down. Pulling an
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* inode in with read_inode() is much preferable to having
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* the GC thread get there first. */
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schedule_timeout_interruptible(msecs_to_jiffies(50));
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if (kthread_should_stop()) {
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D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): kthread_stop() called.\n"));
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goto die;
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}
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/* Put_super will send a SIGKILL and then wait on the sem.
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*/
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while (signal_pending(current) || freezing(current)) {
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siginfo_t info;
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unsigned long signr;
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if (try_to_freeze())
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goto again;
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signr = dequeue_signal_lock(current, ¤t->blocked, &info);
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switch(signr) {
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case SIGSTOP:
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D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n"));
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set_current_state(TASK_STOPPED);
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schedule();
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break;
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case SIGKILL:
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D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n"));
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goto die;
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case SIGHUP:
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D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n"));
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break;
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default:
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D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr));
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}
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}
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/* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
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disallow_signal(SIGHUP);
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D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n"));
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if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
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printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n");
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goto die;
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}
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}
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die:
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spin_lock(&c->erase_completion_lock);
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c->gc_task = NULL;
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spin_unlock(&c->erase_completion_lock);
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complete_and_exit(&c->gc_thread_exit, 0);
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}
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