| 1 | /* |
| 2 | * JFFS2 -- Journalling Flash File System, Version 2. |
| 3 | * |
| 4 | * Copyright © 2001-2007 Red Hat, Inc. |
| 5 | * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org> |
| 6 | * |
| 7 | * Created by David Woodhouse <dwmw2@infradead.org> |
| 8 | * |
| 9 | * For licensing information, see the file 'LICENCE' in this directory. |
| 10 | * |
| 11 | */ |
| 12 | |
| 13 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 14 | |
| 15 | #include <linux/kernel.h> |
| 16 | #include <linux/jffs2.h> |
| 17 | #include <linux/mtd/mtd.h> |
| 18 | #include <linux/completion.h> |
| 19 | #include <linux/sched.h> |
| 20 | #include <linux/freezer.h> |
| 21 | #include <linux/kthread.h> |
| 22 | #include "nodelist.h" |
| 23 | |
| 24 | |
| 25 | static int jffs2_garbage_collect_thread(void *); |
| 26 | |
| 27 | void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c) |
| 28 | { |
| 29 | assert_spin_locked(&c->erase_completion_lock); |
| 30 | if (c->gc_task && jffs2_thread_should_wake(c)) |
| 31 | send_sig(SIGHUP, c->gc_task, 1); |
| 32 | } |
| 33 | |
| 34 | /* This must only ever be called when no GC thread is currently running */ |
| 35 | int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c) |
| 36 | { |
| 37 | struct task_struct *tsk; |
| 38 | int ret = 0; |
| 39 | |
| 40 | BUG_ON(c->gc_task); |
| 41 | |
| 42 | init_completion(&c->gc_thread_start); |
| 43 | init_completion(&c->gc_thread_exit); |
| 44 | |
| 45 | tsk = kthread_run(jffs2_garbage_collect_thread, c, "jffs2_gcd_mtd%d", c->mtd->index); |
| 46 | if (IS_ERR(tsk)) { |
| 47 | pr_warn("fork failed for JFFS2 garbage collect thread: %ld\n", |
| 48 | -PTR_ERR(tsk)); |
| 49 | complete(&c->gc_thread_exit); |
| 50 | ret = PTR_ERR(tsk); |
| 51 | } else { |
| 52 | /* Wait for it... */ |
| 53 | jffs2_dbg(1, "Garbage collect thread is pid %d\n", tsk->pid); |
| 54 | wait_for_completion(&c->gc_thread_start); |
| 55 | ret = tsk->pid; |
| 56 | } |
| 57 | |
| 58 | return ret; |
| 59 | } |
| 60 | |
| 61 | void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c) |
| 62 | { |
| 63 | int wait = 0; |
| 64 | spin_lock(&c->erase_completion_lock); |
| 65 | if (c->gc_task) { |
| 66 | jffs2_dbg(1, "Killing GC task %d\n", c->gc_task->pid); |
| 67 | send_sig(SIGKILL, c->gc_task, 1); |
| 68 | wait = 1; |
| 69 | } |
| 70 | spin_unlock(&c->erase_completion_lock); |
| 71 | if (wait) |
| 72 | wait_for_completion(&c->gc_thread_exit); |
| 73 | } |
| 74 | |
| 75 | static int jffs2_garbage_collect_thread(void *_c) |
| 76 | { |
| 77 | struct jffs2_sb_info *c = _c; |
| 78 | sigset_t hupmask; |
| 79 | |
| 80 | siginitset(&hupmask, sigmask(SIGHUP)); |
| 81 | allow_signal(SIGKILL); |
| 82 | allow_signal(SIGSTOP); |
| 83 | allow_signal(SIGHUP); |
| 84 | |
| 85 | c->gc_task = current; |
| 86 | complete(&c->gc_thread_start); |
| 87 | |
| 88 | set_user_nice(current, 10); |
| 89 | |
| 90 | set_freezable(); |
| 91 | for (;;) { |
| 92 | sigprocmask(SIG_UNBLOCK, &hupmask, NULL); |
| 93 | again: |
| 94 | spin_lock(&c->erase_completion_lock); |
| 95 | if (!jffs2_thread_should_wake(c)) { |
| 96 | set_current_state (TASK_INTERRUPTIBLE); |
| 97 | spin_unlock(&c->erase_completion_lock); |
| 98 | jffs2_dbg(1, "%s(): sleeping...\n", __func__); |
| 99 | schedule(); |
| 100 | } else { |
| 101 | spin_unlock(&c->erase_completion_lock); |
| 102 | } |
| 103 | /* Problem - immediately after bootup, the GCD spends a lot |
| 104 | * of time in places like jffs2_kill_fragtree(); so much so |
| 105 | * that userspace processes (like gdm and X) are starved |
| 106 | * despite plenty of cond_resched()s and renicing. Yield() |
| 107 | * doesn't help, either (presumably because userspace and GCD |
| 108 | * are generally competing for a higher latency resource - |
| 109 | * disk). |
| 110 | * This forces the GCD to slow the hell down. Pulling an |
| 111 | * inode in with read_inode() is much preferable to having |
| 112 | * the GC thread get there first. */ |
| 113 | schedule_timeout_interruptible(msecs_to_jiffies(50)); |
| 114 | |
| 115 | if (kthread_should_stop()) { |
| 116 | jffs2_dbg(1, "%s(): kthread_stop() called\n", __func__); |
| 117 | goto die; |
| 118 | } |
| 119 | |
| 120 | /* Put_super will send a SIGKILL and then wait on the sem. |
| 121 | */ |
| 122 | while (signal_pending(current) || freezing(current)) { |
| 123 | unsigned long signr; |
| 124 | |
| 125 | if (try_to_freeze()) |
| 126 | goto again; |
| 127 | |
| 128 | signr = kernel_dequeue_signal(NULL); |
| 129 | |
| 130 | switch(signr) { |
| 131 | case SIGSTOP: |
| 132 | jffs2_dbg(1, "%s(): SIGSTOP received\n", |
| 133 | __func__); |
| 134 | kernel_signal_stop(); |
| 135 | break; |
| 136 | |
| 137 | case SIGKILL: |
| 138 | jffs2_dbg(1, "%s(): SIGKILL received\n", |
| 139 | __func__); |
| 140 | goto die; |
| 141 | |
| 142 | case SIGHUP: |
| 143 | jffs2_dbg(1, "%s(): SIGHUP received\n", |
| 144 | __func__); |
| 145 | break; |
| 146 | default: |
| 147 | jffs2_dbg(1, "%s(): signal %ld received\n", |
| 148 | __func__, signr); |
| 149 | } |
| 150 | } |
| 151 | /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */ |
| 152 | sigprocmask(SIG_BLOCK, &hupmask, NULL); |
| 153 | |
| 154 | jffs2_dbg(1, "%s(): pass\n", __func__); |
| 155 | if (jffs2_garbage_collect_pass(c) == -ENOSPC) { |
| 156 | pr_notice("No space for garbage collection. Aborting GC thread\n"); |
| 157 | goto die; |
| 158 | } |
| 159 | } |
| 160 | die: |
| 161 | spin_lock(&c->erase_completion_lock); |
| 162 | c->gc_task = NULL; |
| 163 | spin_unlock(&c->erase_completion_lock); |
| 164 | complete_and_exit(&c->gc_thread_exit, 0); |
| 165 | } |