11da177e4SLinus Torvalds /*
21da177e4SLinus Torvalds * JFFS2 -- Journalling Flash File System, Version 2.
31da177e4SLinus Torvalds *
4c00c310eSDavid Woodhouse * Copyright © 2001-2007 Red Hat, Inc.
56088c058SDavid Woodhouse * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org>
61da177e4SLinus Torvalds *
71da177e4SLinus Torvalds * Created by David Woodhouse <dwmw2@infradead.org>
81da177e4SLinus Torvalds *
91da177e4SLinus Torvalds * For licensing information, see the file 'LICENCE' in this directory.
101da177e4SLinus Torvalds *
111da177e4SLinus Torvalds */
121da177e4SLinus Torvalds
135a528957SJoe Perches #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
145a528957SJoe Perches
151da177e4SLinus Torvalds #include <linux/kernel.h>
161da177e4SLinus Torvalds #include <linux/jffs2.h>
171da177e4SLinus Torvalds #include <linux/mtd/mtd.h>
181da177e4SLinus Torvalds #include <linux/completion.h>
193f07c014SIngo Molnar #include <linux/sched/signal.h>
207dfb7103SNigel Cunningham #include <linux/freezer.h>
2191e0955bSGerard Lledo #include <linux/kthread.h>
221da177e4SLinus Torvalds #include "nodelist.h"
231da177e4SLinus Torvalds
241da177e4SLinus Torvalds
251da177e4SLinus Torvalds static int jffs2_garbage_collect_thread(void *);
261da177e4SLinus Torvalds
jffs2_garbage_collect_trigger(struct jffs2_sb_info * c)271da177e4SLinus Torvalds void jffs2_garbage_collect_trigger(struct jffs2_sb_info *c)
281da177e4SLinus Torvalds {
29acb64a43SDavid Woodhouse assert_spin_locked(&c->erase_completion_lock);
301da177e4SLinus Torvalds if (c->gc_task && jffs2_thread_should_wake(c))
311da177e4SLinus Torvalds send_sig(SIGHUP, c->gc_task, 1);
321da177e4SLinus Torvalds }
331da177e4SLinus Torvalds
341da177e4SLinus Torvalds /* This must only ever be called when no GC thread is currently running */
jffs2_start_garbage_collect_thread(struct jffs2_sb_info * c)351da177e4SLinus Torvalds int jffs2_start_garbage_collect_thread(struct jffs2_sb_info *c)
361da177e4SLinus Torvalds {
3791e0955bSGerard Lledo struct task_struct *tsk;
381da177e4SLinus Torvalds int ret = 0;
391da177e4SLinus Torvalds
404b4d1cc7SEric Sesterhenn BUG_ON(c->gc_task);
411da177e4SLinus Torvalds
42fff7afd7SThomas Gleixner init_completion(&c->gc_thread_start);
431da177e4SLinus Torvalds init_completion(&c->gc_thread_exit);
441da177e4SLinus Torvalds
4591e0955bSGerard Lledo tsk = kthread_run(jffs2_garbage_collect_thread, c, "jffs2_gcd_mtd%d", c->mtd->index);
4691e0955bSGerard Lledo if (IS_ERR(tsk)) {
47da320f05SJoe Perches pr_warn("fork failed for JFFS2 garbage collect thread: %ld\n",
48da320f05SJoe Perches -PTR_ERR(tsk));
491da177e4SLinus Torvalds complete(&c->gc_thread_exit);
5091e0955bSGerard Lledo ret = PTR_ERR(tsk);
511da177e4SLinus Torvalds } else {
521da177e4SLinus Torvalds /* Wait for it... */
535a528957SJoe Perches jffs2_dbg(1, "Garbage collect thread is pid %d\n", tsk->pid);
54fff7afd7SThomas Gleixner wait_for_completion(&c->gc_thread_start);
5591e0955bSGerard Lledo ret = tsk->pid;
561da177e4SLinus Torvalds }
571da177e4SLinus Torvalds
581da177e4SLinus Torvalds return ret;
591da177e4SLinus Torvalds }
601da177e4SLinus Torvalds
jffs2_stop_garbage_collect_thread(struct jffs2_sb_info * c)611da177e4SLinus Torvalds void jffs2_stop_garbage_collect_thread(struct jffs2_sb_info *c)
621da177e4SLinus Torvalds {
63e2d48b1aSThomas Gleixner int wait = 0;
641da177e4SLinus Torvalds spin_lock(&c->erase_completion_lock);
651da177e4SLinus Torvalds if (c->gc_task) {
665a528957SJoe Perches jffs2_dbg(1, "Killing GC task %d\n", c->gc_task->pid);
671da177e4SLinus Torvalds send_sig(SIGKILL, c->gc_task, 1);
68e2d48b1aSThomas Gleixner wait = 1;
691da177e4SLinus Torvalds }
701da177e4SLinus Torvalds spin_unlock(&c->erase_completion_lock);
71e2d48b1aSThomas Gleixner if (wait)
721da177e4SLinus Torvalds wait_for_completion(&c->gc_thread_exit);
731da177e4SLinus Torvalds }
741da177e4SLinus Torvalds
jffs2_garbage_collect_thread(void * _c)751da177e4SLinus Torvalds static int jffs2_garbage_collect_thread(void *_c)
761da177e4SLinus Torvalds {
771da177e4SLinus Torvalds struct jffs2_sb_info *c = _c;
78c240837fSOleg Nesterov sigset_t hupmask;
791da177e4SLinus Torvalds
80c240837fSOleg Nesterov siginitset(&hupmask, sigmask(SIGHUP));
811da177e4SLinus Torvalds allow_signal(SIGKILL);
821da177e4SLinus Torvalds allow_signal(SIGSTOP);
83c240837fSOleg Nesterov allow_signal(SIGHUP);
841da177e4SLinus Torvalds
851da177e4SLinus Torvalds c->gc_task = current;
86fff7afd7SThomas Gleixner complete(&c->gc_thread_start);
871da177e4SLinus Torvalds
881da177e4SLinus Torvalds set_user_nice(current, 10);
891da177e4SLinus Torvalds
9083144186SRafael J. Wysocki set_freezable();
911da177e4SLinus Torvalds for (;;) {
92c240837fSOleg Nesterov sigprocmask(SIG_UNBLOCK, &hupmask, NULL);
93e716dd36SDavid Woodhouse again:
94b27cf88eSDavid Woodhouse spin_lock(&c->erase_completion_lock);
951da177e4SLinus Torvalds if (!jffs2_thread_should_wake(c)) {
961da177e4SLinus Torvalds set_current_state (TASK_INTERRUPTIBLE);
97b27cf88eSDavid Woodhouse spin_unlock(&c->erase_completion_lock);
989c261b33SJoe Perches jffs2_dbg(1, "%s(): sleeping...\n", __func__);
991da177e4SLinus Torvalds schedule();
100c240837fSOleg Nesterov } else {
101b27cf88eSDavid Woodhouse spin_unlock(&c->erase_completion_lock);
102c240837fSOleg Nesterov }
103efab0b5dSAndres Salomon /* Problem - immediately after bootup, the GCD spends a lot
104efab0b5dSAndres Salomon * of time in places like jffs2_kill_fragtree(); so much so
105efab0b5dSAndres Salomon * that userspace processes (like gdm and X) are starved
106efab0b5dSAndres Salomon * despite plenty of cond_resched()s and renicing. Yield()
107efab0b5dSAndres Salomon * doesn't help, either (presumably because userspace and GCD
108efab0b5dSAndres Salomon * are generally competing for a higher latency resource -
109efab0b5dSAndres Salomon * disk).
110efab0b5dSAndres Salomon * This forces the GCD to slow the hell down. Pulling an
111efab0b5dSAndres Salomon * inode in with read_inode() is much preferable to having
112efab0b5dSAndres Salomon * the GC thread get there first. */
113efab0b5dSAndres Salomon schedule_timeout_interruptible(msecs_to_jiffies(50));
1141da177e4SLinus Torvalds
11591e0955bSGerard Lledo if (kthread_should_stop()) {
1169c261b33SJoe Perches jffs2_dbg(1, "%s(): kthread_stop() called\n", __func__);
11791e0955bSGerard Lledo goto die;
11891e0955bSGerard Lledo }
11991e0955bSGerard Lledo
1201da177e4SLinus Torvalds /* Put_super will send a SIGKILL and then wait on the sem.
1211da177e4SLinus Torvalds */
122e136e769SRafael J. Wysocki while (signal_pending(current) || freezing(current)) {
1231da177e4SLinus Torvalds unsigned long signr;
1241da177e4SLinus Torvalds
125e716dd36SDavid Woodhouse if (try_to_freeze())
126e716dd36SDavid Woodhouse goto again;
127e716dd36SDavid Woodhouse
128961366a0SEric W. Biederman signr = kernel_dequeue_signal();
1291da177e4SLinus Torvalds
1301da177e4SLinus Torvalds switch(signr) {
1311da177e4SLinus Torvalds case SIGSTOP:
1329c261b33SJoe Perches jffs2_dbg(1, "%s(): SIGSTOP received\n",
1339c261b33SJoe Perches __func__);
1349a13049eSOleg Nesterov kernel_signal_stop();
1351da177e4SLinus Torvalds break;
1361da177e4SLinus Torvalds
1371da177e4SLinus Torvalds case SIGKILL:
1389c261b33SJoe Perches jffs2_dbg(1, "%s(): SIGKILL received\n",
1399c261b33SJoe Perches __func__);
1401da177e4SLinus Torvalds goto die;
1411da177e4SLinus Torvalds
1421da177e4SLinus Torvalds case SIGHUP:
1439c261b33SJoe Perches jffs2_dbg(1, "%s(): SIGHUP received\n",
1449c261b33SJoe Perches __func__);
1451da177e4SLinus Torvalds break;
1461da177e4SLinus Torvalds default:
1479c261b33SJoe Perches jffs2_dbg(1, "%s(): signal %ld received\n",
1489c261b33SJoe Perches __func__, signr);
1491da177e4SLinus Torvalds }
1501da177e4SLinus Torvalds }
1511da177e4SLinus Torvalds /* We don't want SIGHUP to interrupt us. STOP and KILL are OK though. */
152c240837fSOleg Nesterov sigprocmask(SIG_BLOCK, &hupmask, NULL);
1531da177e4SLinus Torvalds
1549c261b33SJoe Perches jffs2_dbg(1, "%s(): pass\n", __func__);
1551da177e4SLinus Torvalds if (jffs2_garbage_collect_pass(c) == -ENOSPC) {
156da320f05SJoe Perches pr_notice("No space for garbage collection. Aborting GC thread\n");
1571da177e4SLinus Torvalds goto die;
1581da177e4SLinus Torvalds }
1591da177e4SLinus Torvalds }
1601da177e4SLinus Torvalds die:
1611da177e4SLinus Torvalds spin_lock(&c->erase_completion_lock);
1621da177e4SLinus Torvalds c->gc_task = NULL;
1631da177e4SLinus Torvalds spin_unlock(&c->erase_completion_lock);
164*cead1855SEric W. Biederman kthread_complete_and_exit(&c->gc_thread_exit, 0);
1651da177e4SLinus Torvalds }
166