The translation from LBA to index of provisioning map (map_storep) is used
in various places (map_state(), map_region(), and unmap_region()).  But it
is not correctly calculated if scsi_debug_unmap_alignment is zero.

This introduces correct translation functions between LBA and index
of  provisioning map:

        static unsigned long lba_to_map_index(sector_t lba);
        static sector_t map_index_to_lba(unsigned long index);

Actual bug fixes with using these functions will be done by forthcoming
patches.

Signed-off-by: Akinobu Mita <akinobu.m...@gmail.com>
Cc: "James E.J. Bottomley" <jbottom...@parallels.com>
Cc: Douglas Gilbert <dgilb...@interlog.com>
Cc: "Martin K. Petersen" <martin.peter...@oracle.com>
Cc: linux-scsi@vger.kernel.org
---
 drivers/scsi/scsi_debug.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 4b5d388..c6de36c 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -1997,6 +1997,23 @@ out:
        return ret;
 }
 
+static unsigned long lba_to_map_index(sector_t lba)
+{
+       if (scsi_debug_unmap_alignment) {
+               lba += scsi_debug_unmap_granularity -
+                       scsi_debug_unmap_alignment;
+       }
+       do_div(lba, scsi_debug_unmap_granularity);
+
+       return lba;
+}
+
+static sector_t map_index_to_lba(unsigned long index)
+{
+       return index * scsi_debug_unmap_granularity -
+               scsi_debug_unmap_alignment;
+}
+
 static unsigned int map_state(sector_t lba, unsigned int *num)
 {
        unsigned int granularity, alignment, mapped;
-- 
1.8.1.4

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