Re: [PATCH 3/7] xen-blkfront: handle Xen major numbers other thanXENVBD

From: Konrad Rzeszutek Wilk
Date: Tue Feb 22 2011 - 14:21:21 EST

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In reply to: stefano . stabellini: "[PATCH 3/7] xen-blkfront: handle Xen major numbers other than XENVBD"
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On Wed, Feb 16, 2011 at 05:53:03PM +0000, stefano.stabellini@xxxxxxxxxxxxx wrote:
> From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>
> 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@xxxxxxxxxxxxx>
> Acked-by: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
> ---
> drivers/block/xen-blkfront.c | 79 +++++++++++++++++++++++++++++++++++--
> include/xen/interface/io/blkif.h | 21 ++++++++++
> 2 files changed, 95 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
> index d7aa39e..64d9c6d 100644
> --- a/drivers/block/xen-blkfront.c
> +++ b/drivers/block/xen-blkfront.c
> @@ -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)

0 / 256 ? Why not just 0?

> +#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);
> - 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;
> @@ -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);
> diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h
> index c2d1fa4..68dd2b4 100644
> --- a/include/xen/interface/io/blkif.h
> +++ b/include/xen/interface/io/blkif.h
> @@ -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__ */
> --
> 1.5.6.5
--
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Next message: Kees Cook: "Re: [PATCH 2/2] debugfs: only allow root access to debugginginterfaces"
Previous message: Sergei Shtylyov: "Re: [PATCH] USB 10/100 RJ45 Ethernet Network Adapter"
In reply to: stefano . stabellini: "[PATCH 3/7] xen-blkfront: handle Xen major numbers other than XENVBD"
Next in thread: stefano . stabellini: "[PATCH 4/7] xen: make the ballon driver work for hvm domains"
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