From: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
Some programs like fdisk, require HDIO_GETGEO to work, which requires we
implement getgeo.
We set all hd_geometry members to 1, because this way fdisk
math will not try its crazy geometry math and get stuff totally wrong.
I was trying to get some values that will make fdisk Want to align
first sector on 4K (like 8, 16, 20, ... sectors) but nothing worked,
I searched the net the math is not your regular simple multiplication
at all.
If you managed to get these magic values please tell me. I would love to
solve this.
But for now we use 4k physical_sector for fixing fdisk alignment
issues, and setting these here to something that will not make
fdisk serve us with crazy numbers.
Signed-off-by: Boaz Harrosh <boaz@xxxxxxxxxxxxx>
---
drivers/block/brd.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/drivers/block/brd.c b/drivers/block/brd.c
index a10a0a9..8be3747 100644
--- a/drivers/block/brd.c
+++ b/drivers/block/brd.c
@@ -19,6 +19,7 @@
#include <linux/radix-tree.h>
#include <linux/fs.h>
#include <linux/slab.h>
+#include <linux/hdreg.h>
#include <asm/uaccess.h>
@@ -424,6 +425,23 @@ static int brd_ioctl(struct block_device *bdev, fmode_t mode,
return error;
}
+static int brd_getgeo(struct block_device *bd, struct hd_geometry *geo)
+{
+ /* Just tell fdisk to get out of the way. The math here is so
+ * convoluted and does not make any sense at all. With all 1s
+ * The math just gets out of the way.
+ * NOTE: I was trying to get some values that will make fdisk
+ * Want to align first sector on 4K (like 8, 16, 20, ... sectors) but
+ * nothing worked, I searched the net the math is not your regular
+ * simple multiplication at all. If you managed to get these please
+ * fix here. For now we use 4k physical sectors for this
+ */
+ geo->heads = 1;
+ geo->sectors = 1;
+ geo->cylinders = 1;
+ return 0;
+}
+
static const struct block_device_operations brd_fops = {
.owner = THIS_MODULE,
.rw_page = brd_rw_page,
@@ -431,6 +449,7 @@ static const struct block_device_operations brd_fops = {
#ifdef CONFIG_BLK_DEV_XIP
.direct_access = brd_direct_access,
#endif
+ .getgeo = brd_getgeo,
};
/*
--
1.9.3
--
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