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- /*
- * JFFS2 -- Journalling Flash File System, Version 2.
- *
- * Copyright © 2001-2007 Red Hat, Inc.
- * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
- *
- * Created by David Woodhouse <dwmw2@infradead.org>
- *
- * For licensing information, see the file 'LICENCE' in this directory.
- *
- */
- #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
- #include <linux/kernel.h>
- #include <linux/jffs2.h>
- #include <linux/mtd/mtd.h>
- #include <linux/completion.h>
- #include <linux/sched.h>
- #include <linux/freezer.h>
- #include <linux/kthread.h>
- #include "nodelist.h"
- static int jffs2_garbage_collect_thread(void *);
- void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
- {
- assert_spin_locked(&c->erase_completion_lock);
- if (c->gc_task && jffs2_thread_should_wake(c))
- send_sig(SIGHUP, c->gc_task, 1);
- }
- /* This must only ever be called when no GC thread is currently running */
- int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c)
- {
- struct task_struct *tsk;
- int ret = 0;
- BUG_ON(c->gc_task);
- init_completion(&c->gc_thread_start);
- init_completion(&c->gc_thread_exit);
- tsk = kthread_run(jffs2_garbage_collect_thread, c, "jffs2_gcd_mtd%d", c->mtd->index);
- if (IS_ERR(tsk)) {
- pr_warn("fork failed for JFFS2 garbage collect thread: %ld\n",
- -PTR_ERR(tsk));
- complete(&c->gc_thread_exit);
- ret = PTR_ERR(tsk);
- } else {
- /* Wait for it... */
- jffs2_dbg(1, "Garbage collect thread is pid %d\n", tsk->pid);
- wait_for_completion(&c->gc_thread_start);
- ret = tsk->pid;
- }
- return ret;
- }
- void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
- {
- int wait = 0;
- spin_lock(&c->erase_completion_lock);
- if (c->gc_task) {
- jffs2_dbg(1, "Killing GC task %d\n", c->gc_task->pid);
- send_sig(SIGKILL, c->gc_task, 1);
- wait = 1;
- }
- spin_unlock(&c->erase_completion_lock);
- if (wait)
- wait_for_completion(&c->gc_thread_exit);
- }
- static int jffs2_garbage_collect_thread(void *_c)
- {
- struct jffs2_sb_info *c = _c;
- sigset_t hupmask;
- siginitset(&hupmask, sigmask(SIGHUP));
- allow_signal(SIGKILL);
- allow_signal(SIGSTOP);
- allow_signal(SIGHUP);
- c->gc_task = current;
- complete(&c->gc_thread_start);
- set_user_nice(current, 10);
- set_freezable();
- for (;;) {
- sigprocmask(SIG_UNBLOCK, &hupmask, NULL);
- again:
- spin_lock(&c->erase_completion_lock);
- if (!jffs2_thread_should_wake(c)) {
- set_current_state (TASK_INTERRUPTIBLE);
- spin_unlock(&c->erase_completion_lock);
- jffs2_dbg(1, "%s(): sleeping...\n", __func__);
- schedule();
- } else {
- spin_unlock(&c->erase_completion_lock);
- }
- /* Problem - immediately after bootup, the GCD spends a lot
- * of time in places like jffs2_kill_fragtree(); so much so
- * that userspace processes (like gdm and X) are starved
- * despite plenty of cond_resched()s and renicing. Yield()
- * doesn't help, either (presumably because userspace and GCD
- * are generally competing for a higher latency resource -
- * disk).
- * This forces the GCD to slow the hell down. Pulling an
- * inode in with read_inode() is much preferable to having
- * the GC thread get there first. */
- schedule_timeout_interruptible(msecs_to_jiffies(50));
- if (kthread_should_stop()) {
- jffs2_dbg(1, "%s(): kthread_stop() called\n", __func__);
- goto die;
- }
- /* Put_super will send a SIGKILL and then wait on the sem.
- */
- while (signal_pending(current) || freezing(current)) {
- unsigned long signr;
- if (try_to_freeze())
- goto again;
- signr = kernel_dequeue_signal(NULL);
- switch(signr) {
- case SIGSTOP:
- jffs2_dbg(1, "%s(): SIGSTOP received\n",
- __func__);
- kernel_signal_stop();
- break;
- case SIGKILL:
- jffs2_dbg(1, "%s(): SIGKILL received\n",
- __func__);
- goto die;
- case SIGHUP:
- jffs2_dbg(1, "%s(): SIGHUP received\n",
- __func__);
- break;
- default:
- jffs2_dbg(1, "%s(): signal %ld received\n",
- __func__, signr);
- }
- }
- /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
- sigprocmask(SIG_BLOCK, &hupmask, NULL);
- jffs2_dbg(1, "%s(): pass\n", __func__);
- if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
- pr_notice("No space for garbage collection. Aborting GC thread\n");
- goto die;
- }
- }
- die:
- spin_lock(&c->erase_completion_lock);
- c->gc_task = NULL;
- spin_unlock(&c->erase_completion_lock);
- complete_and_exit(&c->gc_thread_exit, 0);
- }
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