bcachefs: Make sure to initialize j->last_flushed

If the journal reclaim thread makes it to the timeout without ever
initializing j->last_flushed, we could end up sleeping for a very long
time.
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/journal.c

@@ -1189,6 +1189,8 @@ void __bch2_journal_debug_to_text(struct printbuf *out, struct journal *j)
 	       "nr noflush writes:\t%llu\n"
 	       "nr direct reclaim:\t%llu\n"
 	       "nr background reclaim:\t%llu\n"
+	       "reclaim kicked:\t\t%u\n"
+	       "reclaim runs in:\t%u ms\n"
 	       "current entry sectors:\t%u\n"
 	       "current entry error:\t%u\n"
 	       "current entry:\t\t",
@@ -1204,6 +1206,8 @@ void __bch2_journal_debug_to_text(struct printbuf *out, struct journal *j)
 	       j->nr_noflush_writes,
 	       j->nr_direct_reclaim,
 	       j->nr_background_reclaim,
+	       j->reclaim_kicked,
+	       jiffies_to_msecs(j->next_reclaim - jiffies),
 	       j->cur_entry_sectors,
 	       j->cur_entry_error);
 

fs/bcachefs/journal_reclaim.c

@@ -677,13 +677,15 @@ int bch2_journal_reclaim(struct journal *j)
 static int bch2_journal_reclaim_thread(void *arg)
 {
 	struct journal *j = arg;
-	unsigned long next;
+	unsigned long delay, now;
 	int ret = 0;
 
 	set_freezable();
 
 	kthread_wait_freezable(test_bit(JOURNAL_RECLAIM_STARTED, &j->flags));
 
+	j->last_flushed = jiffies;
+
 	while (!ret && !kthread_should_stop()) {
 		j->reclaim_kicked = false;
 
@@ -691,18 +693,22 @@ static int bch2_journal_reclaim_thread(void *arg)
 		ret = __bch2_journal_reclaim(j, false);
 		mutex_unlock(&j->reclaim_lock);
 
-		next = j->last_flushed + msecs_to_jiffies(j->reclaim_delay_ms);
+		now = jiffies;
+		delay = msecs_to_jiffies(j->reclaim_delay_ms);
+		j->next_reclaim = j->last_flushed + delay;
+
+		if (!time_in_range(j->next_reclaim, now, now + delay))
+			j->next_reclaim = now + delay;
 
 		while (1) {
-			set_current_state(TASK_INTERRUPTIBLE);
+			set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
 			if (kthread_should_stop())
 				break;
 			if (j->reclaim_kicked)
 				break;
-			if (time_after_eq(jiffies, next))
+			if (time_after_eq(jiffies, j->next_reclaim))
 				break;
-			schedule_timeout(next - jiffies);
-			try_to_freeze();
+			schedule_timeout(j->next_reclaim - jiffies);
 
 		}
 		__set_current_state(TASK_RUNNING);

fs/bcachefs/journal_reclaim.h

@@ -8,11 +8,9 @@ static inline void journal_reclaim_kick(struct journal *j)
 {
 	struct task_struct *p = READ_ONCE(j->reclaim_thread);
 
-	if (p && !j->reclaim_kicked) {
 	j->reclaim_kicked = true;
 	if (p)
 		wake_up_process(p);
-	}
 }
 
 unsigned bch2_journal_dev_buckets_available(struct journal *,

fs/bcachefs/journal_types.h

@@ -248,6 +248,7 @@ struct journal {
 	wait_queue_head_t	reclaim_wait;
 	struct task_struct	*reclaim_thread;
 	bool			reclaim_kicked;
+	unsigned long		next_reclaim;
 	u64			nr_direct_reclaim;
 	u64			nr_background_reclaim;