laptop mode, #2

diff -Nru a/fs/buffer.c b/fs/buffer.c
@@ -88,6 +88,13 @@
 static int osync_buffers_list(struct list_head *);
 static void __refile_buffer(struct buffer_head *);
 
+/*
+ * A global sysctl-controlled flag which puts the machine into "laptop mode"
+ */
+int laptop_mode;
+
+static DECLARE_WAIT_QUEUE_HEAD(kupdate_wait);
+
 /* This is used by some architectures to estimate available memory. */
 atomic_t buffermem_pages = ATOMIC_INIT(0);
 

@@ -995,7 +1002,7 @@
 	dirty *= 100;
 	dirty_limit = tot * bdf_prm.b_un.nfract_stop_bdflush;
 
-	if (dirty > dirty_limit)
+	if (!laptop_mode && dirty > dirty_limit)
 		return 0;
 	return 1;
 }

@@ -1044,6 +1051,8 @@
 void mark_buffer_dirty(struct buffer_head *bh)
 {
 	if (!atomic_set_buffer_dirty(bh)) {
+		if (block_dump)
+			printk("%s: dirtied buffer\n", current->comm);
 		__mark_dirty(bh);
 		balance_dirty();
 	}

@@ -1055,6 +1064,13 @@
 }
 EXPORT_SYMBOL(set_buffer_flushtime);
 
+unsigned long get_buffer_flushtime(void)
+{
+	return bdf_prm.b_un.age_buffer;
+}
+EXPORT_SYMBOL(get_buffer_flushtime);
+
+
 /*
  * A buffer may need to be moved from one buffer list to another
  * (e.g. in case it is not shared any more). Handle this.

@@ -2815,6 +2831,12 @@
 	wake_up_interruptible(&bdflush_wait);
 }
 
+void wakeup_kupdate(void)
+{
+	if (waitqueue_active(&kupdate_wait))
+		wake_up(&kupdate_wait);
+}
+
 /* 
  * Here we attempt to write back old buffers.  We also try to flush inodes 
  * and supers as well, since this function is essentially "update", and 

@@ -2835,7 +2857,9 @@
 
 		spin_lock(&lru_list_lock);
 		bh = lru_list[BUF_DIRTY];
-		if (!bh || time_before(jiffies, bh->b_flushtime))
+		if (!bh)
+			break;
+		if (time_before(jiffies, bh->b_flushtime) && !laptop_mode)
 			break;
 		if (write_some_buffers(NODEV))
 			continue;

@@ -2983,6 +3007,10 @@
 	complete((struct completion *)startup);
 
 	for (;;) {
+		DECLARE_WAITQUEUE(wait, tsk);
+
+		add_wait_queue(&kupdate_wait, &wait);
+
 		/* update interval */
 		interval = bdf_prm.b_un.interval;
 		if (interval) {

@@ -2993,6 +3021,7 @@
 			tsk->state = TASK_STOPPED;
 			schedule(); /* wait for SIGCONT */
 		}
+		remove_wait_queue(&kupdate_wait, &wait);
 		/* check for sigstop */
 		if (signal_pending(tsk)) {
 			int stopped = 0;

@@ -3010,6 +3039,8 @@
 		printk(KERN_DEBUG "kupdate() activated...\n");
 #endif
 		sync_old_buffers();
+		if (laptop_mode)
+			fsync_dev(NODEV);
 		run_task_queue(&tq_disk);
 	}
 }

diff -Nru a/fs/jbd/transaction.c b/fs/jbd/transaction.c
@@ -56,7 +56,11 @@
 	transaction->t_journal = journal;
 	transaction->t_state = T_RUNNING;
 	transaction->t_tid = journal->j_transaction_sequence++;
-	transaction->t_expires = jiffies + journal->j_commit_interval;
+	/*
+	 * have to do it here, otherwise changed age_buffers since boot
+	 * wont have any effect
+	 */
+	transaction->t_expires = jiffies + get_buffer_flushtime();
 	INIT_LIST_HEAD(&transaction->t_jcb);
 
 	/* Set up the commit timer for the new transaction. */

diff -Nru a/include/linux/fs.h b/include/linux/fs.h
@@ -1238,6 +1238,7 @@
 }
 
 extern void set_buffer_flushtime(struct buffer_head *);
+extern unsigned long get_buffer_flushtime(void);
 extern void balance_dirty(void);
 extern int check_disk_change(kdev_t);
 extern int invalidate_inodes(struct super_block *);

@@ -1427,8 +1428,10 @@
 	return get_hash_table(sb->s_dev, block, sb->s_blocksize);
 }
 extern void wakeup_bdflush(void);
+extern void wakeup_kupdate(void);
 extern void put_unused_buffer_head(struct buffer_head * bh);
 extern struct buffer_head * get_unused_buffer_head(int async);
+extern int block_dump;
 
 extern int brw_page(int, struct page *, kdev_t, int [], int);
 

diff -Nru a/include/linux/sysctl.h b/include/linux/sysctl.h
@@ -144,6 +144,8 @@
 	VM_MAX_MAP_COUNT=11,	/* int: Maximum number of active map areas */
 	VM_MIN_READAHEAD=12,    /* Min file readahead */
 	VM_MAX_READAHEAD=13,    /* Max file readahead */
+	VM_LAPTOP_MODE=14,	/* vm laptop mode */
+	VM_BLOCK_DUMP=15,	/* dump data read/write and dirtying */
 };
 
 

diff -Nru a/kernel/sysctl.c b/kernel/sysctl.c
@@ -51,6 +51,8 @@
 extern int core_uses_pid;
 extern char core_pattern[];
 extern int cad_pid;
+extern int laptop_mode;
+extern int block_dump;
 
 /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
 static int maxolduid = 65535;

@@ -280,6 +282,10 @@
 	&vm_max_readahead,sizeof(int), 0644, NULL, &proc_dointvec},
 	{VM_MAX_MAP_COUNT, "max_map_count",
 	 &max_map_count, sizeof(int), 0644, NULL, &proc_dointvec},
+	{VM_LAPTOP_MODE, "laptop_mode",
+	 &laptop_mode, sizeof(int), 0644, NULL, &proc_dointvec},
+	{VM_BLOCK_DUMP, "block_dump",
+	 &block_dump, sizeof(int), 0644, NULL, &proc_dointvec},
 	{0}
 };
 

diff -Nru a/mm/filemap.c b/mm/filemap.c
@@ -166,6 +166,8 @@
 
 			if (mapping && mapping->host)
 				mark_inode_dirty_pages(mapping->host);
+			if (block_dump)
+				printk("%s: dirtied page\n", current->comm);
 		}
 	}
 }