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 set_freezable(); 85 for (;;) { 86 allow_signal(SIGHUP); 87 again: 88 spin_lock(&c->erase_completion_lock); 89 if (!jffs2_thread_should_wake(c)) { 90 set_current_state (TASK_INTERRUPTIBLE); 91 spin_unlock(&c->erase_completion_lock); 92 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread sleeping...\n")); 93 schedule(); 94 } else 95 spin_unlock(&c->erase_completion_lock); 96 97 98 /* Problem - immediately after bootup, the GCD spends a lot 99 * of time in places like jffs2_kill_fragtree(); so much so 100 * that userspace processes (like gdm and X) are starved 101 * despite plenty of cond_resched()s and renicing. Yield() 102 * doesn't help, either (presumably because userspace and GCD 103 * are generally competing for a higher latency resource - 104 * disk). 105 * This forces the GCD to slow the hell down. Pulling an 106 * inode in with read_inode() is much preferable to having 107 * the GC thread get there first. */ 108 schedule_timeout_interruptible(msecs_to_jiffies(50)); 109 110 /* Put_super will send a SIGKILL and then wait on the sem. 111 */ 112 while (signal_pending(current) || freezing(current)) { 113 siginfo_t info; 114 unsigned long signr; 115 116 if (try_to_freeze()) 117 goto again; 118 119 signr = dequeue_signal_lock(current, ¤t->blocked, &info); 120 121 switch(signr) { 122 case SIGSTOP: 123 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n")); 124 set_current_state(TASK_STOPPED); 125 schedule(); 126 break; 127 128 case SIGKILL: 129 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n")); 130 goto die; 131 132 case SIGHUP: 133 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n")); 134 break; 135 default: 136 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr)); 137 } 138 } 139 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */ 140 disallow_signal(SIGHUP); 141 142 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n")); 143 if (jffs2_garbage_collect_pass(c) == -ENOSPC) { 144 printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n"); 145 goto die; 146 } 147 } 148 die: 149 spin_lock(&c->erase_completion_lock); 150 c->gc_task = NULL; 151 spin_unlock(&c->erase_completion_lock); 152 complete_and_exit(&c->gc_thread_exit, 0); 153 } 154