Re: [PATCH 1/2] lib: add generic helper to print sizes rounded to the correct SI range

James Bottomley
2008-08-31T15:42:07Z

On Sun, 2008-08-31 at 16:20 +0100, Simon Arlott wrote:
> On 31/08/08 16:13, James Bottomley wrote:
> > This patch adds the ability to print sizes in either units of 10^3 (SI)
> > or 2^10 (Binary) units. It rounds up to three significant figures and
> > can be used for either memory or storage capacities.
>
> > + const char *units_2[] = {"B", "Kib", "MiB", "GiB", "TiB", "PiB",
>
> I think this should have been "KiB".

Yes, shift slip.

> I'd prefer an option to display these without the "i"...

If anyone ever finds a use for that, possibly ... but with the i is the
NIST way now, so we follow the standards.

> Oh and you need to store the original capacity before it's re-scaled to
> 512 bytes. Outputting sdkp->capacity at that stage it'll be a count of
> 512-byte sectors.

Yes, just trying to avoid a multiplication. I should have just used ffz
instead.

James

---

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index e5e7d78..ef1c06c 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -47,6 +47,7 @@
#include <linux/blkpg.h>
#include <linux/delay.h>
#include <linux/mutex.h>
+#include <linux/string_helpers.h>
#include <asm/uaccess.h>

#include <scsi/scsi.h>
@@ -1429,27 +1430,21 @@ got_data:
*/
sector_size = 512;
}
+ blk_queue_hardsect_size(sdp->request_queue, sector_size);
+
{
- /*
- * The msdos fs needs to know the hardware sector size
- * So I have created this table. See ll_rw_blk.c
- * Jacques Gelinas (Jacques@solucorp.qc.ca)
- */
- int hard_sector = sector_size;
- sector_t sz = (sdkp->capacity/2) * (hard_sector/256);
- struct request_queue *queue = sdp->request_queue;
- sector_t mb = sz;
+ char cap_str_2[10], cap_str_10[10];
+ u64 sz = sdkp->capacity << ffz(~sector_size);

- blk_queue_hardsect_size(queue, hard_sector);
- /* avoid 64-bit division on 32-bit platforms */
- sector_div(sz, 625);
- mb -= sz - 974;
- sector_div(mb, 1950);
+ string_get_size(sz, STRING_UNITS_2, cap_str_2,
+ sizeof(cap_str_2));
+ string_get_size(sz, STRING_UNITS_10, cap_str_10,
+ sizeof(cap_str_10));

sd_printk(KERN_NOTICE, sdkp,
- "%llu %d-byte hardware sectors (%llu MB)\n",
+ "%llu %d-byte hardware sectors: (%s/%s)\n",
(unsigned long long)sdkp->capacity,
- hard_sector, (unsigned long long)mb);
+ sector_size, cap_str_10, cap_str_2);
}

/* Rescale capacity to 512-byte units */