linux-kernel - [PATCH] Implement getgeo for Xen virtual block device.

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Message-Id: <1197822928.16584.7.camel@localhost.localdomain>
Date:	Sun, 16 Dec 2007 16:35:28 +0000
From:	Ian Campbell <ijc@...lion.org.uk>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	virtualization@...ts.linux-foundation.org
Subject: [PATCH] Implement getgeo for Xen virtual block device.

Hi Jeremy,

The below implements the getgeo hook for Xen block devices. Extracted
from the xen-unstable tree where it has been used for ages.

It is useful to have because it allows things like grub2 (used by the
Debian installer images) to work in a guest domain without having to
sprinkle Xen specific hacks around the place.

Signed-off-by: Ian Campbell <ijc@...lion.org.uk>

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 2bdebcb..b0a2e69 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -37,6 +37,7 @@
 
 #include <linux/interrupt.h>
 #include <linux/blkdev.h>
+#include <linux/hdreg.h>
 #include <linux/module.h>
 
 #include <xen/xenbus.h>
@@ -135,6 +136,22 @@ static void blkif_restart_queue_callback(void *arg)
 	schedule_work(&info->work);
 }
 
+int blkif_getgeo(struct block_device *bd, struct hd_geometry *hg)
+{
+	/* We don't have real geometry info, but let's at least return
+	   values consistent with the size of the device */
+	sector_t nsect = get_capacity(bd->bd_disk);
+	sector_t cylinders = nsect;
+
+	hg->heads = 0xff;
+	hg->sectors = 0x3f;
+	sector_div(cylinders, hg->heads * hg->sectors);
+	hg->cylinders = cylinders;
+	if ((sector_t)(hg->cylinders + 1) * hg->heads * hg->sectors < nsect)
+		hg->cylinders = 0xffff;
+	return 0;
+}
+
 /*
  * blkif_queue_request
  *
@@ -939,6 +956,7 @@ static struct block_device_operations xlvbd_block_fops =
 	.owner = THIS_MODULE,
 	.open = blkif_open,
 	.release = blkif_release,
+	.getgeo = blkif_getgeo,
 };
 



-- 
Ian Campbell

'Martyrdom' is the only way a person can become famous without ability.
		-- George Bernard Shaw

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