Commit c80a4209 authored by Stefano Stabellini's avatar Stefano Stabellini
Browse files

xen-blkfront: handle Xen major numbers other than XENVBD 



This patch makes sure blkfront handles correctly virtual device numbers
corresponding to Xen emulated IDE and SCSI disks: in those cases
blkfront translates the major number to XENVBD and the minor number to a
low xvd minor.

Note: this behaviour is different from what old xenlinux PV guests used
to do: they used to steal an IDE or SCSI major number and use it
instead.

Signed-off-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: default avatarJeremy Fitzhardinge <jeremy@goop.org>
parent cff520b9

drivers/block/xen-blkfront.c

+74 −5
Original line number Diff line number Diff line
@@ -120,6 +120,10 @@ static DEFINE_SPINLOCK(minor_lock); 
#define EXTENDED (1<<EXT_SHIFT)

#define VDEV_IS_EXTENDED(dev) ((dev)&(EXTENDED))

#define BLKIF_MINOR_EXT(dev) ((dev)&(~EXTENDED))

#define EMULATED_HD_DISK_MINOR_OFFSET (0)

#define EMULATED_HD_DISK_NAME_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET / 256)

#define EMULATED_SD_DISK_MINOR_OFFSET (EMULATED_HD_DISK_MINOR_OFFSET + (4 * 16))

#define EMULATED_SD_DISK_NAME_OFFSET (EMULATED_HD_DISK_NAME_OFFSET + 4)



#define DEV_NAME	"xvd"	/* name in /dev */
@@ -434,6 +438,65 @@ static void xlvbd_flush(struct blkfront_info *info) 
	       info->feature_flush ? "enabled" : "disabled");

}



static int xen_translate_vdev(int vdevice, int *minor, unsigned int *offset)

{

	int major;

	major = BLKIF_MAJOR(vdevice);

	*minor = BLKIF_MINOR(vdevice);

	switch (major) {

		case XEN_IDE0_MAJOR:

			*offset = (*minor / 64) + EMULATED_HD_DISK_NAME_OFFSET;

			*minor = ((*minor / 64) * PARTS_PER_DISK) +

				EMULATED_HD_DISK_MINOR_OFFSET;

			break;

		case XEN_IDE1_MAJOR:

			*offset = (*minor / 64) + 2 + EMULATED_HD_DISK_NAME_OFFSET;

			*minor = (((*minor / 64) + 2) * PARTS_PER_DISK) +

				EMULATED_HD_DISK_MINOR_OFFSET;

			break;

		case XEN_SCSI_DISK0_MAJOR:

			*offset = (*minor / PARTS_PER_DISK) + EMULATED_SD_DISK_NAME_OFFSET;

			*minor = *minor + EMULATED_SD_DISK_MINOR_OFFSET;

			break;

		case XEN_SCSI_DISK1_MAJOR:

		case XEN_SCSI_DISK2_MAJOR:

		case XEN_SCSI_DISK3_MAJOR:

		case XEN_SCSI_DISK4_MAJOR:

		case XEN_SCSI_DISK5_MAJOR:

		case XEN_SCSI_DISK6_MAJOR:

		case XEN_SCSI_DISK7_MAJOR:

			*offset = (*minor / PARTS_PER_DISK) + 

				((major - XEN_SCSI_DISK1_MAJOR + 1) * 16) +

				EMULATED_SD_DISK_NAME_OFFSET;

			*minor = *minor +

				((major - XEN_SCSI_DISK1_MAJOR + 1) * 16 * PARTS_PER_DISK) +

				EMULATED_SD_DISK_MINOR_OFFSET;

			break;

		case XEN_SCSI_DISK8_MAJOR:

		case XEN_SCSI_DISK9_MAJOR:

		case XEN_SCSI_DISK10_MAJOR:

		case XEN_SCSI_DISK11_MAJOR:

		case XEN_SCSI_DISK12_MAJOR:

		case XEN_SCSI_DISK13_MAJOR:

		case XEN_SCSI_DISK14_MAJOR:

		case XEN_SCSI_DISK15_MAJOR:

			*offset = (*minor / PARTS_PER_DISK) + 

				((major - XEN_SCSI_DISK8_MAJOR + 8) * 16) +

				EMULATED_SD_DISK_NAME_OFFSET;

			*minor = *minor +

				((major - XEN_SCSI_DISK8_MAJOR + 8) * 16 * PARTS_PER_DISK) +

				EMULATED_SD_DISK_MINOR_OFFSET;

			break;

		case XENVBD_MAJOR:

			*offset = *minor / PARTS_PER_DISK;

			break;

		default:

			printk(KERN_WARNING "blkfront: your disk configuration is "

					"incorrect, please use an xvd device instead\n");

			return -ENODEV;

	}

	return 0;

}



static int xlvbd_alloc_gendisk(blkif_sector_t capacity,

			       struct blkfront_info *info,
@@ -441,7 +504,7 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 
{

	struct gendisk *gd;

	int nr_minors = 1;

	int err = -ENODEV;

	int err;

	unsigned int offset;

	int minor;

	int nr_parts;
@@ -456,12 +519,20 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 
	}



	if (!VDEV_IS_EXTENDED(info->vdevice)) {

		minor = BLKIF_MINOR(info->vdevice);

		err = xen_translate_vdev(info->vdevice, &minor, &offset);

		if (err)

			return err;		

 		nr_parts = PARTS_PER_DISK;

	} else {

		minor = BLKIF_MINOR_EXT(info->vdevice);

		nr_parts = PARTS_PER_EXT_DISK;

		offset = minor / nr_parts;

		if (xen_hvm_domain() && offset <= EMULATED_HD_DISK_NAME_OFFSET + 4)

			printk(KERN_WARNING "blkfront: vdevice 0x%x might conflict with "

					"emulated IDE disks,\n\t choose an xvd device name"

					"from xvde on\n", info->vdevice);

	}

	err = -ENODEV;



	if ((minor % nr_parts) == 0)

		nr_minors = nr_parts;
@@ -475,8 +546,6 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity, 
	if (gd == NULL)

		goto release;



	offset = minor / nr_parts;



	if (nr_minors > 1) {

		if (offset < 26)

			sprintf(gd->disk_name, "%s%c", DEV_NAME, 'a' + offset);

include/xen/interface/io/blkif.h

+21 −0
Original line number Diff line number Diff line
@@ -91,4 +91,25 @@ DEFINE_RING_TYPES(blkif, struct blkif_request, struct blkif_response); 
#define VDISK_REMOVABLE    0x2

#define VDISK_READONLY     0x4



/* Xen-defined major numbers for virtual disks, they look strangely

 * familiar */

#define XEN_IDE0_MAJOR	3

#define XEN_IDE1_MAJOR	22

#define XEN_SCSI_DISK0_MAJOR	8

#define XEN_SCSI_DISK1_MAJOR	65

#define XEN_SCSI_DISK2_MAJOR	66

#define XEN_SCSI_DISK3_MAJOR	67

#define XEN_SCSI_DISK4_MAJOR	68

#define XEN_SCSI_DISK5_MAJOR	69

#define XEN_SCSI_DISK6_MAJOR	70

#define XEN_SCSI_DISK7_MAJOR	71

#define XEN_SCSI_DISK8_MAJOR	128

#define XEN_SCSI_DISK9_MAJOR	129

#define XEN_SCSI_DISK10_MAJOR	130

#define XEN_SCSI_DISK11_MAJOR	131

#define XEN_SCSI_DISK12_MAJOR	132

#define XEN_SCSI_DISK13_MAJOR	133

#define XEN_SCSI_DISK14_MAJOR	134

#define XEN_SCSI_DISK15_MAJOR	135



#endif /* __XEN_PUBLIC_IO_BLKIF_H__ */

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