block: implement CONFIG_DEBUG_BLOCK_EXT_DEVT
Extended devt introduces non-contiguos device numbers. This patch
implements a debug option which forces most devt allocations to be
from the extended area and spreads them out. This is enabled by
default if DEBUG_KERNEL is set and achieves...
1. Detects code paths in kernel or userland which expect predetermined
consecutive device numbers.
2. When something goes wrong, avoid corruption as adding to the minor
of earlier partition won't lead to the wrong but valid device.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index d1bb0e1..280d231 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -87,7 +87,13 @@
MODULE_ALIAS_SCSI_DEVICE(TYPE_RBC);
#define SD_PARTS 64
+
+#if !defined(CONFIG_DEBUG_BLOCK_EXT_DEVT)
#define SD_MINORS 16
+#else
+#define SD_MINORS 1
+#endif
+
#define SD_EXT_MINORS (SD_PARTS - SD_MINORS)
static int sd_revalidate_disk(struct gendisk *);