// IO scheduler tapset
// Copyright (C) 2005, 2006 IBM Corp.
//
// This file is part of systemtap, and is free software.  You can
// redistribute it and/or modify it under the terms of the GNU General
// Public License (GPL); either version 2, or (at your option) any
// later version.
// <tapsetdescription>
// This family of probe points is used to probe IO scheduler activities. 
// </tapsetdescription>
%{
#include <linux/blkdev.h>
#include <linux/elevator.h>
%}

/**
 * probe ioscheduler.elv_next_request - Fires when a request is retrieved from the request queue
 * @elevator_name: The type of I/O elevator currently enabled
 */
probe ioscheduler.elv_next_request
	=  %( kernel_v >= "2.6.31" %? 
		kernel.function("blk_peek_request") 
	   %:
		kernel.function("elv_next_request")
	   %)
{
%( kernel_v >= "2.6.10" %?
	elevator_name = kernel_string($q->elevator->elevator_type->elevator_name)
%:
	elevator_name = kernel_string($q->elevator->elevator_name)
%)
}

/**
 * probe ioscheduler.elv_next_request.return - Fires when a request retrieval issues a return signal
 * @req: Address of the request
 * @req_flags: Request flags
 * @disk_major: Disk major number of the request
 * @disk_minor: Disk minor number of the request
 */
probe ioscheduler.elv_next_request.return
        =  %( kernel_v >= "2.6.31" %?
                kernel.function("blk_peek_request").return
           %:   
                kernel.function("elv_next_request").return
           %)
{
	if($return == 0)  {
		req = 0
		req_flags = 0
		disk_major = -1
		disk_minor = -1
	} else {
		req = $return
%( kernel_v >= "2.6.19" %?
		req_flags = $return->cmd_flags
%:
		req_flags = $return->flags
%)
		if($return->rq_disk == 0)  {
			disk_major = -1
			disk_minor = -1
		} else {
			disk_major = $return->rq_disk->major
			disk_minor = $return->rq_disk->first_minor
		}
	}
}

/**
 * probe ioscheduler.elv_add_request - A request was added to the request queue
 * @elevator_name: The type of I/O elevator currently enabled
 * @req: Address of the request
 * @req_flags: Request flags
 * @disk_major: Disk major number of the request
 * @disk_minor: Disk minor number of the request
 */
// when a request is added to the request queue
probe ioscheduler.elv_add_request
	= kernel.function("__elv_add_request")
{
%( kernel_v >= "2.6.10" %?
	elevator_name = kernel_string($q->elevator->elevator_type->elevator_name)
%:
	elevator_name = kernel_string($q->elevator->elevator_name)
%)
	if($rq == 0)  {
		disk_major = -1
		disk_minor = -1
	} else {
		if($rq->rq_disk == 0)  {
			disk_major = -1
			disk_minor = -1
		} else {
			disk_major = $rq->rq_disk->major
			disk_minor = $rq->rq_disk->first_minor
		}
	}

	req = $rq
%( kernel_v >= "2.6.19" %?
	req_flags = $rq==0? 0:$rq->cmd_flags
%:
	req_flags = $rq==0? 0:$rq->flags
%)
}

/**
 * probe ioscheduler.elv_completed_request - Fires when a request is completed
 * @elevator_name: The type of I/O elevator currently enabled
 * @req: Address of the request
 * @req_flags: Request flags
 * @disk_major: Disk major number of the request
 * @disk_minor: Disk minor number of the request
 */
probe ioscheduler.elv_completed_request
	= kernel.function("elv_completed_request")
{
%( kernel_v >= "2.6.10" %?
	elevator_name = kernel_string($q->elevator->elevator_type->elevator_name)
%:
	elevator_name = kernel_string($q->elevator->elevator_name)
%)
	if($rq == 0)  {
		disk_major = -1
		disk_minor = -1
	} else {
		if($rq->rq_disk == 0)  {
			disk_major = -1
			disk_minor = -1
		} else {
			disk_major = $rq->rq_disk->major
			disk_minor = $rq->rq_disk->first_minor
		}
	}

	req = $rq
%( kernel_v >= "2.6.19" %?
	req_flags = $rq==0? 0:$rq->cmd_flags
%:
	req_flags = $rq==0? 0:$rq->flags
%)
}

function disk_major_from_request:long(var_q:long)
%{ /* pure */
	struct request_queue *q = (struct request_queue *)((long)THIS->var_q);
	struct list_head *queue_head = &(q->queue_head);

	if (list_empty(&(q->queue_head))) /* FIXME: deref hazard! */
		THIS->__retvalue = -1;
	else  {
		struct request *rq = list_entry_rq(q->queue_head.next); /* FIXME: deref hazard! */
		struct gendisk *rq_disk = kread(&(rq->rq_disk));
		THIS->__retvalue = kread(&(rq_disk->major));
	}
	CATCH_DEREF_FAULT();
%}

function disk_minor_from_request:long(var_q:long)
%{ /* pure */
	struct request_queue *q = (struct request_queue *)((long)THIS->var_q);
	struct list_head *queue_head = &(q->queue_head);

	if (list_empty(&(q->queue_head))) /* FIXME: deref hazard! */
		THIS->__retvalue = -1;
	else  {
		struct request *rq = list_entry_rq(q->queue_head.next); /* FIXME: deref hazard! */
		struct gendisk *rq_disk = kread(&(rq->rq_disk));
		THIS->__retvalue = kread(&(rq_disk->first_minor));
	}
	CATCH_DEREF_FAULT();
%}