2 * JFFS2 -- Journalling Flash File System, Version 2.
4 * Copyright (C) 2001-2003 Red Hat, Inc.
6 * Created by David Woodhouse <dwmw2@redhat.com>
8 * For licensing information, see the file 'LICENCE' in this directory.
10 * $Id: background.c,v 1.44 2003/10/08 13:29:55 dwmw2 Exp $
14 #include <linux/kernel.h>
15 #include <linux/jffs2.h>
16 #include <linux/mtd/mtd.h>
17 #include <linux/completion.h>
18 #include <linux/suspend.h>
22 static int jffs2_garbage_collect_thread(void *);
23 static int thread_should_wake(struct jffs2_sb_info *c);
25 void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
27 spin_lock(&c->erase_completion_lock);
28 if (c->gc_task && thread_should_wake(c))
29 send_sig(SIGHUP, c->gc_task, 1);
30 spin_unlock(&c->erase_completion_lock);
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)
42 init_MUTEX_LOCKED(&c->gc_thread_start);
43 init_completion(&c->gc_thread_exit);
45 pid = kernel_thread(jffs2_garbage_collect_thread, c, CLONE_FS|CLONE_FILES);
47 printk(KERN_WARNING "fork failed for JFFS2 garbage collect thread: %d\n", -pid);
48 complete(&c->gc_thread_exit);
52 D1(printk(KERN_DEBUG "JFFS2: Garbage collect thread is pid %d\n", pid));
53 down(&c->gc_thread_start);
59 void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
61 spin_lock(&c->erase_completion_lock);
63 D1(printk(KERN_DEBUG "jffs2: Killing GC task %d\n", c->gc_task->pid));
64 send_sig(SIGKILL, c->gc_task, 1);
66 spin_unlock(&c->erase_completion_lock);
67 wait_for_completion(&c->gc_thread_exit);
70 static int jffs2_garbage_collect_thread(void *_c)
72 struct jffs2_sb_info *c = _c;
74 daemonize("jffs2_gcd_mtd%d", c->mtd->index);
75 allow_signal(SIGKILL);
76 allow_signal(SIGSTOP);
77 allow_signal(SIGCONT);
80 up(&c->gc_thread_start);
82 set_user_nice(current, 10);
87 if (!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 thread_should_wake() before
91 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. */
97 if (current->flags & PF_FREEZE) {
99 /* refrigerator() should recalc sigpending for us
100 but doesn't. No matter - allow_signal() will. */
106 /* Put_super will send a SIGKILL and then wait on the sem.
108 while (signal_pending(current)) {
112 signr = dequeue_signal_lock(current, ¤t->blocked, &info);
116 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGSTOP received.\n"));
117 set_current_state(TASK_STOPPED);
122 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGKILL received.\n"));
126 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): SIGHUP received.\n"));
129 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): signal %ld received\n", signr));
132 /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
133 disallow_signal(SIGHUP);
135 D1(printk(KERN_DEBUG "jffs2_garbage_collect_thread(): pass\n"));
136 if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
137 printk(KERN_NOTICE "No space for garbage collection. Aborting GC thread\n");
142 spin_lock(&c->erase_completion_lock);
144 spin_unlock(&c->erase_completion_lock);
145 complete_and_exit(&c->gc_thread_exit, 0);
148 static int thread_should_wake(struct jffs2_sb_info *c)
153 if (c->unchecked_size) {
154 D1(printk(KERN_DEBUG "thread_should_wake(): unchecked_size %d, checked_ino #%d\n",
155 c->unchecked_size, c->checked_ino));
159 /* dirty_size contains blocks on erase_pending_list
160 * those blocks are counted in c->nr_erasing_blocks.
161 * If one block is actually erased, it is not longer counted as dirty_space
162 * but it is counted in c->nr_erasing_blocks, so we add it and subtract it
163 * with c->nr_erasing_blocks * c->sector_size again.
164 * Blocks on erasable_list are counted as dirty_size, but not in c->nr_erasing_blocks
165 * This helps us to force gc and pick eventually a clean block to spread the load.
167 dirty = c->dirty_size + c->erasing_size - c->nr_erasing_blocks * c->sector_size;
169 if (c->nr_free_blocks + c->nr_erasing_blocks < c->resv_blocks_gctrigger &&
170 (dirty > c->nospc_dirty_size))
173 D1(printk(KERN_DEBUG "thread_should_wake(): nr_free_blocks %d, nr_erasing_blocks %d, dirty_size 0x%x: %s\n",
174 c->nr_free_blocks, c->nr_erasing_blocks, c->dirty_size, ret?"yes":"no"));