[4.2.y-ckt stable] Patch "sd: Fix excessive capacity printing on devices with blocks bigger than 512 bytes" has been added to the 4.2.y-ckt tree

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    sd: Fix excessive capacity printing on devices with blocks bigger than 512 bytes

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt8.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

>From 5ff28dfb83caa46d653d9aa618c557e2217b7b19 Mon Sep 17 00:00:00 2001
From: "Martin K. Petersen" <martin.petersen at oracle.com>
Date: Mon, 28 Mar 2016 21:18:56 -0400
Subject: sd: Fix excessive capacity printing on devices with blocks bigger
 than 512 bytes

commit f08bb1e0dbdd0297258d0b8cd4dbfcc057e57b2a upstream.

During revalidate we check whether device capacity has changed before we
decide whether to output disk information or not.

The check for old capacity failed to take into account that we scaled
sdkp->capacity based on the reported logical block size. And therefore
the capacity test would always fail for devices with sectors bigger than
512 bytes and we would print several copies of the same discovery
information.

Avoid scaling sdkp->capacity and instead adjust the value on the fly
when setting the block device capacity and generating fake C/H/S
geometry.

Signed-off-by: Martin K. Petersen <martin.petersen at oracle.com>
Reported-by: Hannes Reinecke <hare at suse.de>
Reviewed-by: Hannes Reinicke <hare at suse.de>
Reviewed-by: Ewan Milne <emilne at redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen at oracle.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/scsi/sd.c | 23 ++++++++---------------
 drivers/scsi/sd.h |  7 ++++++-
 2 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index 441ae2b..ac91a62 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1260,18 +1260,19 @@ static int sd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 	struct scsi_disk *sdkp = scsi_disk(bdev->bd_disk);
 	struct scsi_device *sdp = sdkp->device;
 	struct Scsi_Host *host = sdp->host;
+	sector_t capacity = logical_to_sectors(sdp, sdkp->capacity);
 	int diskinfo[4];

 	/* default to most commonly used values */
-        diskinfo[0] = 0x40;	/* 1 << 6 */
-       	diskinfo[1] = 0x20;	/* 1 << 5 */
-       	diskinfo[2] = sdkp->capacity >> 11;
-
+	diskinfo[0] = 0x40;	/* 1 << 6 */
+	diskinfo[1] = 0x20;	/* 1 << 5 */
+	diskinfo[2] = capacity >> 11;
+
 	/* override with calculated, extended default, or driver values */
 	if (host->hostt->bios_param)
-		host->hostt->bios_param(sdp, bdev, sdkp->capacity, diskinfo);
+		host->hostt->bios_param(sdp, bdev, capacity, diskinfo);
 	else
-		scsicam_bios_param(bdev, sdkp->capacity, diskinfo);
+		scsicam_bios_param(bdev, capacity, diskinfo);

 	geo->heads = diskinfo[0];
 	geo->sectors = diskinfo[1];
@@ -2230,14 +2231,6 @@ got_data:
 	} else
 		sdkp->max_xfer_blocks = SD_DEF_XFER_BLOCKS;

-	/* Rescale capacity to 512-byte units */
-	if (sector_size == 4096)
-		sdkp->capacity <<= 3;
-	else if (sector_size == 2048)
-		sdkp->capacity <<= 2;
-	else if (sector_size == 1024)
-		sdkp->capacity <<= 1;
-
 	blk_queue_physical_block_size(sdp->request_queue,
 				      sdkp->physical_block_size);
 	sdkp->device->sector_size = sector_size;
@@ -2773,7 +2766,7 @@ static int sd_revalidate_disk(struct gendisk *disk)
 	sdkp->disk->queue->limits.max_sectors =
 		min_not_zero(queue_max_hw_sectors(sdkp->disk->queue), max_xfer);

-	set_capacity(disk, sdkp->capacity);
+	set_capacity(disk, logical_to_sectors(sdp, sdkp->capacity));
 	sd_config_write_same(sdkp);
 	kfree(buffer);

diff --git a/drivers/scsi/sd.h b/drivers/scsi/sd.h
index 63ba5ca..0264936 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 blocks */
 	u32		max_xfer_blocks;
 	u32		max_ws_blocks;
 	u32		max_unmap_blocks;
@@ -145,6 +145,11 @@ static inline int scsi_medium_access_command(struct scsi_cmnd *scmd)
 	return 0;
 }

+static inline sector_t logical_to_sectors(struct scsi_device *sdev, sector_t blocks)
+{
+	return blocks << (ilog2(sdev->sector_size) - 9);
+}
+
 /*
  * A DIF-capable target device can be formatted with different
  * protection schemes.  Currently 0 through 3 are defined:
--
2.7.4