diff options
Diffstat (limited to 'kernel/fs/jffs2/background.c')
| -rw-r--r-- | kernel/fs/jffs2/background.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/kernel/fs/jffs2/background.c b/kernel/fs/jffs2/background.c new file mode 100644 index 000000000..bb9cebc9c --- /dev/null +++ b/kernel/fs/jffs2/background.c @@ -0,0 +1,168 @@ +/* + * 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(SIGCONT); + 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)) { + siginfo_t info; + unsigned long signr; + + if (try_to_freeze()) + goto again; + + signr = dequeue_signal_lock(current, ¤t->blocked, &info); + + switch(signr) { + case SIGSTOP: + jffs2_dbg(1, "%s(): SIGSTOP received\n", + __func__); + set_current_state(TASK_STOPPED); + schedule(); + 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); +} |