1 /* 2 * JFFS2 -- Journalling Flash File System, Version 2. 3 * 4 * Copyright (C) 2001-2003 Red Hat, Inc. 5 * 6 * Created by David Woodhouse <dwmw2@infradead.org> 7 * 8 * For licensing information, see the file 'LICENCE' in this directory. 9 * 10 * $Id: background.c,v 1.54 2005/05/20 21:37:12 gleixner Exp $ 11 * 12 */ 13 14 #include <linux/kernel.h> 15 #include <linux/jffs2.h> 16 #include <linux/mtd/mtd.h> 17 #include <linux/completion.h> 18 #include <linux/sched.h> 19 #include <linux/freezer.h> 20 #include "nodelist.h" 21 22 23 static int jffs2_garbage_collect_thread(void *); 24 25 void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c) 26 { 27 spin_lock(&c->erase_completion_lock); 28 if (c->gc_task && jffs2_thread_should_wake(c)) 29 send_sig(SIGHUP, c->gc_task, 1); 30 spin_unlock(&c->erase_completion_lock); 31 } 32 33 /* This must only ever be called when no GC thread is currently running */ 34 int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c) 35 { 36 pid_t pid; 37 int ret = 0; 38 39 BUG_ON(c->gc_task); 40 41 init_completion(&c->gc_thread_start); 42 init_completion(&c->gc_thread_exit); 43 44 pid = kernel_thread(jffs2_garbage_collect_thread, c, CLONE_FS|CLONE_FILES); 45 if (pid < 0) { 46 printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %d\n", -pid); 47 complete(&c->gc_thread_exit); 48 ret = pid; 49 } else { 50 /* Wait for it... */ 51 D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", pid)); 52 wait_for_completion(&c->gc_thread_start); 53 } 54 55 return ret; 56 } 57 58 void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c) 59 { 60 int wait = 0; 61 spin_lock(&c->erase_completion_lock); 62 if (c->gc_task) { 63 D1(printk(KERN_DEBUG "jffs2: Killing GC task %d\n", c->gc_task->pid)); 64 send_sig(SIGKILL, c->gc_task, 1); 65 wait = 1; 66 } 67 spin_unlock(&c->erase_completion_lock); 68 if (wait) 69 wait_for_completion(&c->gc_thread_exit); 70 } 71 72 static int jffs2_garbage_collect_thread(void *_c) 73 { 74 struct jffs2_sb_info *c = _c; 75 76 daemonize("jffs2_gcd_mtd%d", c->mtd->index); 77 allow_signal(SIGKILL); 78 allow_signal(SIGSTOP); 79 allow_signal(SIGCONT); 80 81 c->gc_task = current; 82 complete(&c->gc_thread_start); 83 84 set_user_nice(current, 10); 85 86 for (;;) { 87 allow_signal(SIGHUP); 88 89 if (!jffs2_thread_should_wake(c)) { 90 set_current_state (TASK_INTERRUPTIBLE); 91 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n")); 92 /* Yes, there's a race here; we checked jffs2_thread_should_wake() 93 before setting current->state to TASK_INTERRUPTIBLE. But it doesn't 94 matter - We don't care if we miss a wakeup, because the GC thread 95 is only an optimisation anyway. */ 96 schedule(); 97 } 98 99 if (try_to_freeze()) 100 continue; 101 102 /* This thread is purely an optimisation. But if it runs when 103 other things could be running, it actually makes things a 104 lot worse. Use yield() and put it at the back of the runqueue 105 every time. Especially during boot, pulling an inode in 106 with read_inode() is much preferable to having the GC thread 107 get there first. */ 108 yield(); 109 110 /* Put_super will send a SIGKILL and then wait on the sem. 111 */ 112 while (signal_pending(current)) { 113 siginfo_t info; 114 unsigned long signr; 115 116 signr = dequeue_signal_lock(current, ¤t->blocked, &info); 117 118 switch(signr) { 119 case SIGSTOP: 120 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n")); 121 set_current_state(TASK_STOPPED); 122 schedule(); 123 break; 124 125 case SIGKILL: 126 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n")); 127 goto die; 128 129 case SIGHUP: 130 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n")); 131 break; 132 default: 133 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr)); 134 } 135 } 136 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */ 137 disallow_signal(SIGHUP); 138 139 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n")); 140 if (jffs2_garbage_collect_pass(c) == -ENOSPC) { 141 printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n"); 142 goto die; 143 } 144 } 145 die: 146 spin_lock(&c->erase_completion_lock); 147 c->gc_task = NULL; 148 spin_unlock(&c->erase_completion_lock); 149 complete_and_exit(&c->gc_thread_exit, 0); 150 } 151