Re: [PATCH] sd: fixup capacity calculation for 4k drives

[Hannes Reinecke <hare@suse.de>]

On 03/22/2016 02:16 AM, Martin K. Petersen wrote:
>>>>>> "Hannes" == Hannes Reinecke <hare@suse.de> writes:
> 
> Hannes> in sd_read_capacity() the sdkp->capacity field changes its
> Hannes> meaning: after the call to read_capacity_XX() it carries the
> Hannes> _unscaled_ values, making the comparison between the original
> Hannes> value and the new value always false for drives with a sector
> Hannes> size != 512.  So introduce a 'new_capacity' carrying the new,
> Hannes> scaled, capacity.
> 
> I agree with Christoph.
> 
> How about something like this instead?
> 
I've coded it somewhat different, but this one works as well.
But please modify the description in sd.h, as with this patch
'sdkp->capacity' is the _unscaled_ value.
Might lead to confusion otherwise.

diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 5f2a84a..5ed7434 100644
--- a/drivers/scsi/sd.h
+++ b/drivers/scsi/sd.h
@@ -65,7 +65,7 @@ struct scsi_disk {
        struct device   dev;
        struct gendisk  *disk;
        atomic_t        openers;
-       sector_t        capacity;       /* size in 512-byte sectors */
+       sector_t        capacity;       /* size in logical sectors */
        u32             max_xfer_blocks;
        u32             opt_xfer_blocks;
        u32             max_ws_blocks;

(Apologies for the mangled patch)

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@suse.de			               +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html