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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: Christian Borntraeger <borntraeger@de.ibm.com>
CC: Christoph Hellwig <hch@lst.de>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Christian Borntraeger 2012-05-24 13:22:55 +02:00 committed by Kevin Wolf
parent c2d76497b6
commit 136be99e6e
1 changed files with 16 additions and 1 deletions
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17
hw/virtio-blk.c
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@ -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;
blkcfg.sectors = secs & ~s->sector_mask;
/*
* 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;