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[Xen-devel] [PATCH 3/7] xen-blkfront: handle Xen major numbers other than XENVBD



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)
+#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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