drivers/block/lguest_blk.c - linux - Git at Google

 /* A simple block driver for lguest.
  *
  * Copyright 2006 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 //#define DEBUG
 #include <linux/init.h>
 #include <linux/types.h>
 #include <linux/blkdev.h>
 #include <linux/interrupt.h>
 #include <linux/lguest_bus.h>

 static char next_block_index = 'a';

 struct blockdev
 {
 	spinlock_t lock;

 	/* The disk structure for the kernel. */
 	struct gendisk *disk;

 	/* The major number for this disk. */
 	int major;
 	int irq;

 	unsigned long phys_addr;
 	/* The mapped block page. */
 	struct lguest_block_page *lb_page;

 	/* We only have a single request outstanding at a time. */
 	struct lguest_dma dma;
 	struct request *req;
 };

 /* Jens gave me this nice helper to end all chunks of a request. */
 static void end_entire_request(struct request *req, int uptodate)
 {
 	if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
 		BUG();
 	add_disk_randomness(req->rq_disk);
 	blkdev_dequeue_request(req);
 	end_that_request_last(req, uptodate);
 }

 static irqreturn_t lgb_irq(int irq, void *_bd)
 {
 	struct blockdev *bd = _bd;
 	unsigned long flags;

 	if (!bd->req) {
 		pr_debug("No work!\n");
 		return IRQ_NONE;
 	}

 	if (!bd->lb_page->result) {
 		pr_debug("No result!\n");
 		return IRQ_NONE;
 	}

 	spin_lock_irqsave(&bd->lock, flags);
 	end_entire_request(bd->req, bd->lb_page->result == 1);
 	bd->req = NULL;
 	bd->dma.used_len = 0;
 	blk_start_queue(bd->disk->queue);
 	spin_unlock_irqrestore(&bd->lock, flags);
 	return IRQ_HANDLED;
 }

 static unsigned int req_to_dma(struct request *req, struct lguest_dma *dma)
 {
 	unsigned int i = 0, idx, len = 0;
 	struct bio *bio;

 	rq_for_each_bio(bio, req) {
 		struct bio_vec *bvec;
 		bio_for_each_segment(bvec, bio, idx) {
 			BUG_ON(i == LGUEST_MAX_DMA_SECTIONS);
 			BUG_ON(!bvec->bv_len);
 			dma->addr[i] = page_to_phys(bvec->bv_page)
 				+ bvec->bv_offset;
 			dma->len[i] = bvec->bv_len;
 			len += bvec->bv_len;
 			i++;
 		}
 	}
 	if (i < LGUEST_MAX_DMA_SECTIONS)
 		dma->len[i] = 0;
 	return len;
 }

 static void empty_dma(struct lguest_dma *dma)
 {
 	dma->len[0] = 0;
 }

 static void setup_req(struct blockdev *bd,
 		      int type, struct request *req, struct lguest_dma *dma)
 {
 	bd->lb_page->type = type;
 	bd->lb_page->sector = req->sector;
 	bd->lb_page->result = 0;
 	bd->req = req;
 	bd->lb_page->bytes = req_to_dma(req, dma);
 }

 static void do_write(struct blockdev *bd, struct request *req)
 {
 	struct lguest_dma send;

 	pr_debug("lgb: WRITE sector %li\n", (long)req->sector);
 	setup_req(bd, 1, req, &send);

 	lguest_send_dma(bd->phys_addr, &send);
 }

 static void do_read(struct blockdev *bd, struct request *req)
 {
 	struct lguest_dma ping;

 	pr_debug("lgb: READ sector %li\n", (long)req->sector);
 	setup_req(bd, 0, req, &bd->dma);

 	empty_dma(&ping);
 	lguest_send_dma(bd->phys_addr, &ping);
 }

 static void do_lgb_request(struct request_queue *q)
 {
 	struct blockdev *bd;
 	struct request *req;

 again:
 	req = elv_next_request(q);
 	if (!req)
 		return;

 	bd = req->rq_disk->private_data;
 	/* Sometimes we get repeated requests after blk_stop_queue. */
 	if (bd->req)
 		return;

 	if (!blk_fs_request(req)) {
 		pr_debug("Got non-command 0x%08x\n", req->cmd_type);
 		req->errors++;
 		end_entire_request(req, 0);
 		goto again;
 	}

 	if (rq_data_dir(req) == WRITE)
 		do_write(bd, req);
 	else
 		do_read(bd, req);

 	/* Wait for interrupt to tell us it's done. */
 	blk_stop_queue(q);
 }

 static struct block_device_operations lguestblk_fops = {
 	.owner = THIS_MODULE,
 };

 static int lguestblk_probe(struct lguest_device *lgdev)
 {
 	struct blockdev *bd;
 	int err;
 	int irqflags = IRQF_SHARED;

 	bd = kmalloc(sizeof(*bd), GFP_KERNEL);
 	if (!bd)
 		return -ENOMEM;

 	spin_lock_init(&bd->lock);
 	bd->irq = lgdev_irq(lgdev);
 	bd->req = NULL;
 	bd->dma.used_len = 0;
 	bd->dma.len[0] = 0;
 	bd->phys_addr = (lguest_devices[lgdev->index].pfn << PAGE_SHIFT);

 	bd->lb_page = lguest_map(bd->phys_addr, 1);
 	if (!bd->lb_page) {
 		err = -ENOMEM;
 		goto out_free_bd;
 	}

 	bd->major = register_blkdev(0, "lguestblk");
 	if (bd->major < 0) {
 		err = bd->major;
 		goto out_unmap;
 	}

 	bd->disk = alloc_disk(1);
 	if (!bd->disk) {
 		err = -ENOMEM;
 		goto out_unregister_blkdev;
 	}

 	bd->disk->queue = blk_init_queue(do_lgb_request, &bd->lock);
 	if (!bd->disk->queue) {
 		err = -ENOMEM;
 		goto out_put_disk;
 	}

 	/* We can only handle a certain number of sg entries */
 	blk_queue_max_hw_segments(bd->disk->queue, LGUEST_MAX_DMA_SECTIONS);
 	/* Buffers must not cross page boundaries */
 	blk_queue_segment_boundary(bd->disk->queue, PAGE_SIZE-1);

 	sprintf(bd->disk->disk_name, "lgb%c", next_block_index++);
 	if (lguest_devices[lgdev->index].features & LGUEST_DEVICE_F_RANDOMNESS)
 		irqflags |= IRQF_SAMPLE_RANDOM;
 	err = request_irq(bd->irq, lgb_irq, irqflags, bd->disk->disk_name, bd);
 	if (err)
 		goto out_cleanup_queue;

 	err = lguest_bind_dma(bd->phys_addr, &bd->dma, 1, bd->irq);
 	if (err)
 		goto out_free_irq;

 	bd->disk->major = bd->major;
 	bd->disk->first_minor = 0;
 	bd->disk->private_data = bd;
 	bd->disk->fops = &lguestblk_fops;
 	/* This is initialized to the disk size by the other end. */
 	set_capacity(bd->disk, bd->lb_page->num_sectors);
 	add_disk(bd->disk);

 	printk(KERN_INFO "%s: device %i at major %d\n",
 	       bd->disk->disk_name, lgdev->index, bd->major);

 	lgdev->private = bd;
 	return 0;

 out_free_irq:
 	free_irq(bd->irq, bd);
 out_cleanup_queue:
 	blk_cleanup_queue(bd->disk->queue);
 out_put_disk:
 	put_disk(bd->disk);
 out_unregister_blkdev:
 	unregister_blkdev(bd->major, "lguestblk");
 out_unmap:
 	lguest_unmap(bd->lb_page);
 out_free_bd:
 	kfree(bd);
 	return err;
 }

 static struct lguest_driver lguestblk_drv = {
 	.name = "lguestblk",
 	.owner = THIS_MODULE,
 	.device_type = LGUEST_DEVICE_T_BLOCK,
 	.probe = lguestblk_probe,
 };

 static __init int lguestblk_init(void)
 {
 	return register_lguest_driver(&lguestblk_drv);
 }
 module_init(lguestblk_init);

 MODULE_DESCRIPTION("Lguest block driver");
 MODULE_LICENSE("GPL");
	/* A simple block driver for lguest.
	*
	* Copyright 2006 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	*/
	//#define DEBUG
	#include <linux/init.h>
	#include <linux/types.h>
	#include <linux/blkdev.h>
	#include <linux/interrupt.h>
	#include <linux/lguest_bus.h>

	static char next_block_index = 'a';

	struct blockdev
	{
	spinlock_t lock;

	/* The disk structure for the kernel. */
	struct gendisk *disk;

	/* The major number for this disk. */
	int major;
	int irq;

	unsigned long phys_addr;
	/* The mapped block page. */
	struct lguest_block_page *lb_page;

	/* We only have a single request outstanding at a time. */
	struct lguest_dma dma;
	struct request *req;
	};

	/* Jens gave me this nice helper to end all chunks of a request. */
	static void end_entire_request(struct request *req, int uptodate)
	{
	if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
	BUG();
	add_disk_randomness(req->rq_disk);
	blkdev_dequeue_request(req);
	end_that_request_last(req, uptodate);
	}

	static irqreturn_t lgb_irq(int irq, void *_bd)
	{
	struct blockdev *bd = _bd;
	unsigned long flags;

	if (!bd->req) {
	pr_debug("No work!\n");
	return IRQ_NONE;
	}

	if (!bd->lb_page->result) {
	pr_debug("No result!\n");
	return IRQ_NONE;
	}

	spin_lock_irqsave(&bd->lock, flags);
	end_entire_request(bd->req, bd->lb_page->result == 1);
	bd->req = NULL;
	bd->dma.used_len = 0;
	blk_start_queue(bd->disk->queue);
	spin_unlock_irqrestore(&bd->lock, flags);
	return IRQ_HANDLED;
	}

	static unsigned int req_to_dma(struct request req, struct lguest_dma dma)
	{
	unsigned int i = 0, idx, len = 0;
	struct bio *bio;

	rq_for_each_bio(bio, req) {
	struct bio_vec *bvec;
	bio_for_each_segment(bvec, bio, idx) {
	BUG_ON(i == LGUEST_MAX_DMA_SECTIONS);
	BUG_ON(!bvec->bv_len);
	dma->addr[i] = page_to_phys(bvec->bv_page)
	+ bvec->bv_offset;
	dma->len[i] = bvec->bv_len;
	len += bvec->bv_len;
	i++;
	}
	}
	if (i < LGUEST_MAX_DMA_SECTIONS)
	dma->len[i] = 0;
	return len;
	}

	static void empty_dma(struct lguest_dma *dma)
	{
	dma->len[0] = 0;
	}

	static void setup_req(struct blockdev *bd,
	int type, struct request req, struct lguest_dma dma)
	{
	bd->lb_page->type = type;
	bd->lb_page->sector = req->sector;
	bd->lb_page->result = 0;
	bd->req = req;
	bd->lb_page->bytes = req_to_dma(req, dma);
	}

	static void do_write(struct blockdev bd, struct request req)
	{
	struct lguest_dma send;

	pr_debug("lgb: WRITE sector %li\n", (long)req->sector);
	setup_req(bd, 1, req, &send);

	lguest_send_dma(bd->phys_addr, &send);
	}

	static void do_read(struct blockdev bd, struct request req)
	{
	struct lguest_dma ping;

	pr_debug("lgb: READ sector %li\n", (long)req->sector);
	setup_req(bd, 0, req, &bd->dma);

	empty_dma(&ping);
	lguest_send_dma(bd->phys_addr, &ping);
	}

	static void do_lgb_request(struct request_queue *q)
	{
	struct blockdev *bd;
	struct request *req;

	again:
	req = elv_next_request(q);
	if (!req)
	return;

	bd = req->rq_disk->private_data;
	/* Sometimes we get repeated requests after blk_stop_queue. */
	if (bd->req)
	return;

	if (!blk_fs_request(req)) {
	pr_debug("Got non-command 0x%08x\n", req->cmd_type);
	req->errors++;
	end_entire_request(req, 0);
	goto again;
	}

	if (rq_data_dir(req) == WRITE)
	do_write(bd, req);
	else
	do_read(bd, req);

	/* Wait for interrupt to tell us it's done. */
	blk_stop_queue(q);
	}

	static struct block_device_operations lguestblk_fops = {
	.owner = THIS_MODULE,
	};

	static int lguestblk_probe(struct lguest_device *lgdev)
	{
	struct blockdev *bd;
	int err;
	int irqflags = IRQF_SHARED;

	bd = kmalloc(sizeof(*bd), GFP_KERNEL);
	if (!bd)
	return -ENOMEM;

	spin_lock_init(&bd->lock);
	bd->irq = lgdev_irq(lgdev);
	bd->req = NULL;
	bd->dma.used_len = 0;
	bd->dma.len[0] = 0;
	bd->phys_addr = (lguest_devices[lgdev->index].pfn << PAGE_SHIFT);

	bd->lb_page = lguest_map(bd->phys_addr, 1);
	if (!bd->lb_page) {
	err = -ENOMEM;
	goto out_free_bd;
	}

	bd->major = register_blkdev(0, "lguestblk");
	if (bd->major < 0) {
	err = bd->major;
	goto out_unmap;
	}

	bd->disk = alloc_disk(1);
	if (!bd->disk) {
	err = -ENOMEM;
	goto out_unregister_blkdev;
	}

	bd->disk->queue = blk_init_queue(do_lgb_request, &bd->lock);
	if (!bd->disk->queue) {
	err = -ENOMEM;
	goto out_put_disk;
	}

	/* We can only handle a certain number of sg entries */
	blk_queue_max_hw_segments(bd->disk->queue, LGUEST_MAX_DMA_SECTIONS);
	/* Buffers must not cross page boundaries */
	blk_queue_segment_boundary(bd->disk->queue, PAGE_SIZE-1);

	sprintf(bd->disk->disk_name, "lgb%c", next_block_index++);
	if (lguest_devices[lgdev->index].features & LGUEST_DEVICE_F_RANDOMNESS)
	irqflags \|= IRQF_SAMPLE_RANDOM;
	err = request_irq(bd->irq, lgb_irq, irqflags, bd->disk->disk_name, bd);
	if (err)
	goto out_cleanup_queue;

	err = lguest_bind_dma(bd->phys_addr, &bd->dma, 1, bd->irq);
	if (err)
	goto out_free_irq;

	bd->disk->major = bd->major;
	bd->disk->first_minor = 0;
	bd->disk->private_data = bd;
	bd->disk->fops = &lguestblk_fops;
	/* This is initialized to the disk size by the other end. */
	set_capacity(bd->disk, bd->lb_page->num_sectors);
	add_disk(bd->disk);

	printk(KERN_INFO "%s: device %i at major %d\n",
	bd->disk->disk_name, lgdev->index, bd->major);

	lgdev->private = bd;
	return 0;

	out_free_irq:
	free_irq(bd->irq, bd);
	out_cleanup_queue:
	blk_cleanup_queue(bd->disk->queue);
	out_put_disk:
	put_disk(bd->disk);
	out_unregister_blkdev:
	unregister_blkdev(bd->major, "lguestblk");
	out_unmap:
	lguest_unmap(bd->lb_page);
	out_free_bd:
	kfree(bd);
	return err;
	}

	static struct lguest_driver lguestblk_drv = {
	.name = "lguestblk",
	.owner = THIS_MODULE,
	.device_type = LGUEST_DEVICE_T_BLOCK,
	.probe = lguestblk_probe,
	};

	static __init int lguestblk_init(void)
	{
	return register_lguest_driver(&lguestblk_drv);
	}
	module_init(lguestblk_init);

	MODULE_DESCRIPTION("Lguest block driver");
	MODULE_LICENSE("GPL");