1 /* 2 * JFFS2 -- Journalling Flash File System, Version 2. 3 * 4 * Copyright © 2001-2007 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 */ 11 12 #include <linux/kernel.h> 13 #include <linux/jffs2.h> 14 #include <linux/mtd/mtd.h> 15 #include <linux/completion.h> 16 #include <linux/sched.h> 17 #include <linux/freezer.h> 18 #include "nodelist.h" 19 20 21 static int jffs2_garbage_collect_thread(void *); 22 23 void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c) 24 { 25 spin_lock(&c->erase_completion_lock); 26 if (c->gc_task && jffs2_thread_should_wake(c)) 27 send_sig(SIGHUP, c->gc_task, 1); 28 spin_unlock(&c->erase_completion_lock); 29 } 30 31 /* This must only ever be called when no GC thread is currently running */ 32 int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c) 33 { 34 pid_t pid; 35 int ret = 0; 36 37 BUG_ON(c->gc_task); 38 39 init_completion(&c->gc_thread_start); 40 init_completion(&c->gc_thread_exit); 41 42 pid = kernel_thread(jffs2_garbage_collect_thread, c, CLONE_FS|CLONE_FILES); 43 if (pid < 0) { 44 printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %d\n", -pid); 45 complete(&c->gc_thread_exit); 46 ret = pid; 47 } else { 48 /* Wait for it... */ 49 D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", pid)); 50 wait_for_completion(&c->gc_thread_start); 51 } 52 53 return ret; 54 } 55 56 void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c) 57 { 58 int wait = 0; 59 spin_lock(&c->erase_completion_lock); 60 if (c->gc_task) { 61 D1(printk(KERN_DEBUG "jffs2: Killing GC task %d\n", c->gc_task->pid)); 62 send_sig(SIGKILL, c->gc_task, 1); 63 wait = 1; 64 } 65 spin_unlock(&c->erase_completion_lock); 66 if (wait) 67 wait_for_completion(&c->gc_thread_exit); 68 } 69 70 static int jffs2_garbage_collect_thread(void *_c) 71 { 72 struct jffs2_sb_info *c = _c; 73 74 daemonize("jffs2_gcd_mtd%d", c->mtd->index); 75 allow_signal(SIGKILL); 76 allow_signal(SIGSTOP); 77 allow_signal(SIGCONT); 78 79 c->gc_task = current; 80 complete(&c->gc_thread_start); 81 82 set_user_nice(current, 10); 83 84 for (;;) { 85 allow_signal(SIGHUP); 86 again: 87 if (!jffs2_thread_should_wake(c)) { 88 set_current_state (TASK_INTERRUPTIBLE); 89 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n")); 90 /* Yes, there's a race here; we checked jffs2_thread_should_wake() 91 before setting current->state to TASK_INTERRUPTIBLE. But it doesn't 92 matter - We don't care if we miss a wakeup, because the GC thread 93 is only an optimisation anyway. */ 94 schedule(); 95 } 96 97 /* This thread is purely an optimisation. But if it runs when 98 other things could be running, it actually makes things a 99 lot worse. Use yield() and put it at the back of the runqueue 100 every time. Especially during boot, pulling an inode in 101 with read_inode() is much preferable to having the GC thread 102 get there first. */ 103 yield(); 104 105 /* Put_super will send a SIGKILL and then wait on the sem. 106 */ 107 while (signal_pending(current)) { 108 siginfo_t info; 109 unsigned long signr; 110 111 if (try_to_freeze()) 112 goto again; 113 114 signr = dequeue_signal_lock(current, ¤t->blocked, &info); 115 116 switch(signr) { 117 case SIGSTOP: 118 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n")); 119 set_current_state(TASK_STOPPED); 120 schedule(); 121 break; 122 123 case SIGKILL: 124 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n")); 125 goto die; 126 127 case SIGHUP: 128 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n")); 129 break; 130 default: 131 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr)); 132 } 133 } 134 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */ 135 disallow_signal(SIGHUP); 136 137 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n")); 138 if (jffs2_garbage_collect_pass(c) == -ENOSPC) { 139 printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n"); 140 goto die; 141 } 142 } 143 die: 144 spin_lock(&c->erase_completion_lock); 145 c->gc_task = NULL; 146 spin_unlock(&c->erase_completion_lock); 147 complete_and_exit(&c->gc_thread_exit, 0); 148 } 149