patch-2.3.99-pre1 linux/drivers/block/elevator.c

• Lines: 151
• Date: Sun Mar 12 19:32:57 2000
• Orig file: v2.3.51/linux/drivers/block/elevator.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.3.51/linux/drivers/block/elevator.c linux/drivers/block/elevator.c
@@ -0,0 +1,150 @@
+/*
+ *  linux/drivers/block/elevator.c
+ *
+ *  Block device elevator/IO-scheduler.
+ *
+ *  Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE
+ */
+
+#include <linux/fs.h>
+#include <linux/blkdev.h>
+#include <linux/elevator.h>
+#include <linux/blk.h>
+#include <asm/uaccess.h>
+
+static void elevator_default(struct request * req, elevator_t * elevator,
+			     struct list_head * real_head,
+			     struct list_head * head, int orig_latency)
+{
+	struct list_head * entry = real_head, * point = NULL;
+	struct request * tmp;
+	int sequence = elevator->sequence;
+	int latency = orig_latency -= elevator->nr_segments, pass = 0;
+	int point_latency = 0xbeefbeef;
+
+	while ((entry = entry->prev) != head) {
+		if (!point && latency >= 0) {
+			point = entry;
+			point_latency = latency;
+		}
+		tmp = blkdev_entry_to_request(entry);
+		if (elevator_sequence_before(tmp->elevator_sequence, sequence) || !tmp->q)
+			break;
+		if (latency >= 0) {
+			if (IN_ORDER(tmp, req) ||
+			    (pass && !IN_ORDER(tmp, blkdev_next_request(tmp))))
+				goto link;
+		}
+		latency += tmp->nr_segments;
+		pass = 1;
+	}
+
+	if (point) {
+		entry = point;
+		latency = point_latency;
+	}
+
+ link:
+	list_add(&req->queue, entry);
+	req->elevator_sequence = elevator_sequence(elevator, latency);
+}
+
+#ifdef ELEVATOR_DEBUG
+void elevator_debug(request_queue_t * q, kdev_t dev)
+{
+	int read_pendings = 0, nr_segments = 0;
+	elevator_t * elevator = &q->elevator;
+	struct list_head * entry = &q->queue_head;
+	static int counter;
+
+	if (counter++ % 100)
+		return;
+
+	while ((entry = entry->prev) != &q->queue_head)
+	{
+		struct request * req;
+
+		req = blkdev_entry_to_request(entry);
+		if (req->cmd != READ && req->cmd != WRITE && (req->q || req->nr_segments))
+			printk(KERN_WARNING
+			       "%s: elevator req->cmd %d req->nr_segments %u req->q %p\n",
+			       kdevname(dev), req->cmd, req->nr_segments, req->q);
+		if (!req->q) {
+			if (req->nr_segments)
+				printk(KERN_WARNING
+				       "%s: elevator req->q NULL req->nr_segments %u\n",
+				       kdevname(dev), req->nr_segments);
+			continue;
+		}
+		if (req->cmd == READ)
+			read_pendings++;
+		nr_segments += req->nr_segments;
+	}
+
+	if (read_pendings != elevator->read_pendings)
+	{
+		printk(KERN_WARNING
+		       "%s: elevator read_pendings %d should be %d\n",
+		       kdevname(dev), elevator->read_pendings,
+		       read_pendings);
+		elevator->read_pendings = read_pendings;
+	}
+	if (nr_segments != elevator->nr_segments)
+	{
+		printk(KERN_WARNING
+		       "%s: elevator nr_segments %d should be %d\n",
+		       kdevname(dev), elevator->nr_segments,
+		       nr_segments);
+		elevator->nr_segments = nr_segments;
+	}
+}
+#endif
+
+int blkelvget_ioctl(elevator_t * elevator, blkelv_ioctl_arg_t * arg)
+{
+	int ret;
+	blkelv_ioctl_arg_t output;
+
+	output.queue_ID			= elevator;
+	output.read_latency		= elevator->read_latency;
+	output.write_latency		= elevator->write_latency;
+	output.max_bomb_segments	= elevator->max_bomb_segments;
+
+	ret = -EFAULT;
+	if (copy_to_user(arg, &output, sizeof(blkelv_ioctl_arg_t)))
+		goto out;
+	ret = 0;
+ out:
+	return ret;
+}
+
+int blkelvset_ioctl(elevator_t * elevator, const blkelv_ioctl_arg_t * arg)
+{
+	blkelv_ioctl_arg_t input;
+	int ret;
+
+	ret = -EFAULT;
+	if (copy_from_user(&input, arg, sizeof(blkelv_ioctl_arg_t)))
+		goto out;
+
+	ret = -EINVAL;
+	if (input.read_latency < 0)
+		goto out;
+	if (input.write_latency < 0)
+		goto out;
+	if (input.max_bomb_segments <= 0)
+		goto out;
+
+	elevator->read_latency		= input.read_latency;
+	elevator->write_latency		= input.write_latency;
+	elevator->max_bomb_segments	= input.max_bomb_segments;
+
+	ret = 0;
+ out:
+	return ret;
+}
+
+void elevator_init(elevator_t * elevator)
+{
+	*elevator = ELEVATOR_DEFAULTS;
+}