sunvdc: compute vdisk geometry from capacity

[ Upstream commit de5b73f08468b4fc5e2f6d1505f650262622f78b ]

The LDom diskserver doesn't return reliable geometry data. In addition,
the types for all fields in the vio_disk_geom are u16, which were being
truncated in the cast into the u8's of the Linux struct hd_geometry.

Modify vdc_getgeo() to compute the geometry from the disk's capacity in a
manner consistent with xen-blkfront::blkif_getgeo().

Signed-off-by: Dwight Engen <dwight.engen@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/block/sunvdc.c b/drivers/block/sunvdc.c
index 66ddf704ad7f695235b0ab1295bc0f24151eda77..1616ad091a5ed513316e7e348167194bc792806a 100644 (file)
--- a/drivers/block/sunvdc.c
+++ b/drivers/block/sunvdc.c
@@ -70,7 +70,6 @@ struct vdc_port {
 
        char                    disk_name[32];
 
-       struct vio_disk_geom    geom;
        struct vio_disk_vtoc    label;
 };
 
@@ -103,11 +102,15 @@ static inline u32 vdc_tx_dring_avail(struct vio_dring_state *dr)
 static int vdc_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 {
        struct gendisk *disk = bdev->bd_disk;
-       struct vdc_port *port = disk->private_data;
+       sector_t nsect = get_capacity(disk);
+       sector_t cylinders = nsect;
 
-       geo->heads = (u8) port->geom.num_hd;
-       geo->sectors = (u8) port->geom.num_sec;
-       geo->cylinders = port->geom.num_cyl;
+       geo->heads = 0xff;
+       geo->sectors = 0x3f;
+       sector_div(cylinders, geo->heads * geo->sectors);
+       geo->cylinders = cylinders;
+       if ((sector_t)(geo->cylinders + 1) * geo->heads * geo->sectors < nsect)
+               geo->cylinders = 0xffff;
 
        return 0;
 }
@@ -714,16 +717,18 @@ static int probe_disk(struct vdc_port *port)
                if (port->vdisk_size == -1)
                        return -ENODEV;
        } else {
+               struct vio_disk_geom geom;
+
                err = generic_request(port, VD_OP_GET_DISKGEOM,
-                                     &port->geom, sizeof(port->geom));
+                                     &geom, sizeof(geom));
                if (err < 0) {
                        printk(KERN_ERR PFX "VD_OP_GET_DISKGEOM returns "
                               "error %d\n", err);
                        return err;
                }
-               port->vdisk_size = ((u64)port->geom.num_cyl *
-                                   (u64)port->geom.num_hd *
-                                   (u64)port->geom.num_sec);
+               port->vdisk_size = ((u64)geom.num_cyl *
+                                   (u64)geom.num_hd *
+                                   (u64)geom.num_sec);
        }
 
        q = blk_init_queue(do_vdc_request, &port->vio.lock);