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xen-blkfront: handle Xen major numbers other than XENVBD
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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: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Jeremy Fitzhardinge <jeremy@goop.org>
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Stefano Stabellini committed Feb 25, 2011
1 parent cff520b commit c80a420
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Showing 2 changed files with 95 additions and 5 deletions.
79 changes: 74 additions & 5 deletions drivers/block/xen-blkfront.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 */

Expand Down Expand Up @@ -434,14 +438,73 @@ 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,
u16 vdisk_info, u16 sector_size)
{
struct gendisk *gd;
int nr_minors = 1;
int err = -ENODEV;
int err;
unsigned int offset;
int minor;
int nr_parts;
Expand All @@ -456,12 +519,20 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
}

if (!VDEV_IS_EXTENDED(info->vdevice)) {
minor = BLKIF_MINOR(info->vdevice);
nr_parts = PARTS_PER_DISK;
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;
Expand All @@ -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);
Expand Down
21 changes: 21 additions & 0 deletions include/xen/interface/io/blkif.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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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