From: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
With current values fdisk does the wrong thing. On small disks
it will offer 40 (20K) as first possible sector.
With this patch fdisk will offer 8 (4k) as possible first
sector, which is what we want.
Note that current code had a BUG with anything bigger than
64G because hd_geometry->cylinders is ushort and it would
overflow at this value. Anyway capacity is not calculated
through getgeo so it does not matter what we set for cylinders.
I have tested with cfdisk parted/gparted and they behave the
same after this patch, with fdisk I have better expected behavior
after this patch.
Is there any other test I need to perform that might be affected
by this?
Signed-off-by: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
---
drivers/block/pmem.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/block/pmem.c b/drivers/block/pmem.c
index b415b61..600d225 100644
--- a/drivers/block/pmem.c
+++ b/drivers/block/pmem.c
@@ -40,10 +40,16 @@ struct pmem_device {
static int pmem_getgeo(struct block_device *bd, struct hd_geometry *geo)
{
- /* some standard values */
- geo->heads = 1 << 6;
- geo->sectors = 1 << 5;
- geo->cylinders = get_capacity(bd->bd_disk) >> 11;
+ /* Just tell fdisk to get out of the way. The CHS math here is so
+ * convoluted and does not make any sense at all. With all 1s
+ * The math just gets out of the way.
+ * When doing the usual lying to fdisk with the (64,32,X) common at the
+ * rest of the Kernel, fdisk will offer 34 as first sector, with this
+ * here plus the 4K physical_block_size it will offer 8 (4K)
+ */
+ geo->heads = 1;
+ geo->sectors = 1;
+ geo->cylinders = 1;
return 0;
}
--
1.9.3
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