Commit 136be99e authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Kevin Wolf
Browse files

virtio-blk: Fix geometry sector calculation 



Currently the sector value for the geometry is masked, even if the
user usesa command line parameter that explicitely gives a number.
This breaks dasd devices on s390. A dasd device can have
a physical block size of 4096 (== same for logical block size)
and a typcial geometry of 15 heads and 12 sectors per cyl.
The ibm partition detection relies on a correct geometry
reported by the device. Unfortunately the current code changes
12 to 8. This would be necessary if the total size is
not a multiple of logical sector size,  but for dasd this
is not the case.

This patch checks the device size and only applies sector
mask if necessary.

Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
CC: Christoph Hellwig <hch@lst.de>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent c2d76497

hw/virtio-blk.c

+16 −1
Original line number Diff line number Diff line
@@ -491,7 +491,22 @@ static void virtio_blk_update_config(VirtIODevice *vdev, uint8_t *config) 
    stw_raw(&blkcfg.min_io_size, s->conf->min_io_size / blk_size);

    stw_raw(&blkcfg.opt_io_size, s->conf->opt_io_size / blk_size);

    blkcfg.heads = heads;

    /*

     * We must ensure that the block device capacity is a multiple of

     * the logical block size. If that is not the case, lets use

     * sector_mask to adopt the geometry to have a correct picture.

     * For those devices where the capacity is ok for the given geometry

     * we dont touch the sector value of the geometry, since some devices

     * (like s390 dasd) need a specific value. Here the capacity is already

     * cyls*heads*secs*blk_size and the sector value is not block size

     * divided by 512 - instead it is the amount of blk_size blocks

     * per track (cylinder).

     */

    if (bdrv_getlength(s->bs) /  heads / secs % blk_size) {

        blkcfg.sectors = secs & ~s->sector_mask;

    } else {

        blkcfg.sectors = secs;

    }

    blkcfg.size_max = 0;

    blkcfg.physical_block_exp = get_physical_block_exp(s->conf);

    blkcfg.alignment_offset = 0;