virtio: add virtio disk geometry feature

Rather than faking up some geometry, allow the backend to push the disk
geometry via virtio pci config option.  Keep the old geo code around for
compatibility.

Signed-off-by: Ryan Harper <ryanh@us.ibm.com>
Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (modified to single struct)

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 78be6b8c89e0c00d8973fb83238743c538f6b4c0..84e064ffee5229e73d2f9f45af19a3ec581f5315 100644 (file)
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -157,10 +157,25 @@ static int virtblk_ioctl(struct inode *inode, struct file *filp,
 /* We provide getgeo only to please some old bootloader/partitioning tools */
 static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
 {
-       /* some standard values, similar to sd */
-       geo->heads = 1 << 6;
-       geo->sectors = 1 << 5;
-       geo->cylinders = get_capacity(bd->bd_disk) >> 11;
+       struct virtio_blk *vblk = bd->bd_disk->private_data;
+       struct virtio_blk_geometry vgeo;
+       int err;
+
+       /* see if the host passed in geometry config */
+       err = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_GEOMETRY,
+                               offsetof(struct virtio_blk_config, geometry),
+                               &vgeo);
+
+       if (!err) {
+               geo->heads = vgeo.heads;
+               geo->sectors = vgeo.sectors;
+               geo->cylinders = vgeo.cylinders;
+       } else {
+               /* some standard values, similar to sd */
+               geo->heads = 1 << 6;
+               geo->sectors = 1 << 5;
+               geo->cylinders = get_capacity(bd->bd_disk) >> 11;
+       }
        return 0;
 }
 
@@ -310,6 +325,7 @@ static struct virtio_device_id id_table[] = {
 
 static unsigned int features[] = {
        VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX,
+       VIRTIO_BLK_F_GEOMETRY,
 };
 
 static struct virtio_driver virtio_blk = {

diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h
index c75a9e82b924ecfa6b0885a49d37d51f1b3510f2..d4695a3356d018f4198df0d5813070cc4b5cf5ad 100644 (file)
--- a/include/linux/virtio_blk.h
+++ b/include/linux/virtio_blk.h
@@ -9,6 +9,7 @@
 #define VIRTIO_BLK_F_BARRIER   0       /* Does host support barriers? */
 #define VIRTIO_BLK_F_SIZE_MAX  1       /* Indicates maximum segment size */
 #define VIRTIO_BLK_F_SEG_MAX   2       /* Indicates maximum # of segments */
+#define VIRTIO_BLK_F_GEOMETRY  4       /* Legacy geometry available  */
 
 struct virtio_blk_config
 {
@@ -18,6 +19,12 @@ struct virtio_blk_config
        __le32 size_max;
        /* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
        __le32 seg_max;
+       /* geometry the device (if VIRTIO_BLK_F_GEOMETRY) */
+       struct virtio_blk_geometry {
+               __le16 cylinders;
+               __u8 heads;
+               __u8 sectors;
+       } geometry;
 } __attribute__((packed));
 
 /* These two define direction. */