diff mbox series

[v2,1/2] scsi: scsi_debug: adjust num_parts to create equally sized partitions

Message ID 20200902211434.9979-2-jpittman@redhat.com
State New
Headers show
Series scsi_debug: improve num_parts usage | expand

Commit Message

John Pittman Sept. 2, 2020, 9:14 p.m. UTC 
Currently when using the num_parts parameter, partitions are aligned
and the end sector is one prior to the next start.  This creates
different sized partitions. Create instead equally sized partitions by
trimming the end of each partition to the size of the smallest
partition.  This aligns better with what one would expect from
automatically created partitions and can be helpful with testing
things such as raid which often expect legs of the same size.
Minimal space is lost as the initial partition starting size is
calculated by dividing num_sectors by sdebug_num_parts.

Signed-off-by: John Pittman <jpittman@redhat.com>
---
 drivers/scsi/scsi_debug.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index 1ad7260d4758..ada0361eac83 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -5257,7 +5257,7 @@  static int scsi_debug_host_reset(struct scsi_cmnd *SCpnt)
 static void sdebug_build_parts(unsigned char *ramp, unsigned long store_size)
 {
 	struct msdos_partition *pp;
-	int starts[SDEBUG_MAX_PARTS + 2];
+	int starts[SDEBUG_MAX_PARTS + 2], max_part_secs;
 	int sectors_per_part, num_sectors, k;
 	int heads_by_sects, start_sec, end_sec;
 
@@ -5273,9 +5273,13 @@  static void sdebug_build_parts(unsigned char *ramp, unsigned long store_size)
 			   / sdebug_num_parts;
 	heads_by_sects = sdebug_heads * sdebug_sectors_per;
 	starts[0] = sdebug_sectors_per;
-	for (k = 1; k < sdebug_num_parts; ++k)
+	max_part_secs = sectors_per_part;
+	for (k = 1; k < sdebug_num_parts; ++k) {
 		starts[k] = ((k * sectors_per_part) / heads_by_sects)
 			    * heads_by_sects;
+		if (starts[k] - starts[k - 1] < max_part_secs)
+			max_part_secs = starts[k] - starts[k - 1];
+	}
 	starts[sdebug_num_parts] = num_sectors;
 	starts[sdebug_num_parts + 1] = 0;
 
@@ -5284,7 +5288,7 @@  static void sdebug_build_parts(unsigned char *ramp, unsigned long store_size)
 	pp = (struct msdos_partition *)(ramp + 0x1be);
 	for (k = 0; starts[k + 1]; ++k, ++pp) {
 		start_sec = starts[k];
-		end_sec = starts[k + 1] - 1;
+		end_sec = starts[k] + max_part_secs - 1;
 		pp->boot_ind = 0;
 
 		pp->cyl = start_sec / heads_by_sects;