linux-vybrid_public/drivers/xen/blkback/vbd.c

/******************************************************************************
 * blkback/vbd.c
 *
 * Routines for managing virtual block devices (VBDs).
 *
 * Copyright (c) 2003-2005, Keir Fraser & Steve Hand
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include "common.h"

#define vbd_sz(_v)   ((_v)->bdev->bd_part ?				\
		      (_v)->bdev->bd_part->nr_sects : get_capacity((_v)->bdev->bd_disk))

unsigned long long vbd_size(struct vbd *vbd)
{
	return vbd_sz(vbd);
}

unsigned int vbd_info(struct vbd *vbd)
{
	return vbd->type | (vbd->readonly?VDISK_READONLY:0);
}

unsigned long vbd_secsize(struct vbd *vbd)
{
	return bdev_hardsect_size(vbd->bdev);
}

int vbd_create(blkif_t *blkif, blkif_vdev_t handle, unsigned major,
	       unsigned minor, int readonly, int cdrom)
{
	struct vbd *vbd;
	struct block_device *bdev;

	vbd = &blkif->vbd;
	vbd->handle   = handle;
	vbd->readonly = readonly;
	vbd->type     = 0;

	vbd->pdevice  = MKDEV(major, minor);

	bdev = open_by_devnum(vbd->pdevice,
			      vbd->readonly ? FMODE_READ : FMODE_WRITE);

	if (IS_ERR(bdev)) {
		DPRINTK("vbd_creat: device %08x could not be opened.\n",
			vbd->pdevice);
		return -ENOENT;
	}

	vbd->bdev = bdev;

	if (vbd->bdev->bd_disk == NULL) {
		DPRINTK("vbd_creat: device %08x doesn't exist.\n",
			vbd->pdevice);
		vbd_free(vbd);
		return -ENOENT;
	}

	if (vbd->bdev->bd_disk->flags & GENHD_FL_CD || cdrom)
		vbd->type |= VDISK_CDROM;
	if (vbd->bdev->bd_disk->flags & GENHD_FL_REMOVABLE)
		vbd->type |= VDISK_REMOVABLE;

	DPRINTK("Successful creation of handle=%04x (dom=%u)\n",
		handle, blkif->domid);
	return 0;
}

void vbd_free(struct vbd *vbd)
{
	if (vbd->bdev)
		blkdev_put(vbd->bdev, vbd->readonly ? FMODE_READ : FMODE_WRITE);
	vbd->bdev = NULL;
}

int vbd_translate(struct phys_req *req, blkif_t *blkif, int operation)
{
	struct vbd *vbd = &blkif->vbd;
	int rc = -EACCES;

	if ((operation != READ) && vbd->readonly)
		goto out;

	if (unlikely((req->sector_number + req->nr_sects) > vbd_sz(vbd)))
		goto out;

	req->dev  = vbd->pdevice;
	req->bdev = vbd->bdev;
	rc = 0;

 out:
	return rc;
}