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-rw-r--r--block/genhd.c38
-rw-r--r--drivers/ide/ide-disk.c6
-rw-r--r--drivers/scsi/sd.c6
-rw-r--r--lib/Kconfig.debug16
4 files changed, 63 insertions, 3 deletions
diff --git a/block/genhd.c b/block/genhd.c
index ee4b13520e59..67e5a59ced2a 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -299,6 +299,38 @@ EXPORT_SYMBOL(unregister_blkdev);
static struct kobj_map *bdev_map;
/**
+ * blk_mangle_minor - scatter minor numbers apart
+ * @minor: minor number to mangle
+ *
+ * Scatter consecutively allocated @minor number apart if MANGLE_DEVT
+ * is enabled. Mangling twice gives the original value.
+ *
+ * RETURNS:
+ * Mangled value.
+ *
+ * CONTEXT:
+ * Don't care.
+ */
+static int blk_mangle_minor(int minor)
+{
+#ifdef CONFIG_DEBUG_BLOCK_EXT_DEVT
+ int i;
+
+ for (i = 0; i < MINORBITS / 2; i++) {
+ int low = minor & (1 << i);
+ int high = minor & (1 << (MINORBITS - 1 - i));
+ int distance = MINORBITS - 1 - 2 * i;
+
+ minor ^= low | high; /* clear both bits */
+ low <<= distance; /* swap the positions */
+ high >>= distance;
+ minor |= low | high; /* and set */
+ }
+#endif
+ return minor;
+}
+
+/**
* blk_alloc_devt - allocate a dev_t for a partition
* @part: partition to allocate dev_t for
* @gfp_mask: memory allocation flag
@@ -339,7 +371,7 @@ int blk_alloc_devt(struct hd_struct *part, dev_t *devt)
return -EBUSY;
}
- *devt = MKDEV(BLOCK_EXT_MAJOR, idx);
+ *devt = MKDEV(BLOCK_EXT_MAJOR, blk_mangle_minor(idx));
return 0;
}
@@ -361,7 +393,7 @@ void blk_free_devt(dev_t devt)
if (MAJOR(devt) == BLOCK_EXT_MAJOR) {
mutex_lock(&ext_devt_mutex);
- idr_remove(&ext_devt_idr, MINOR(devt));
+ idr_remove(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
mutex_unlock(&ext_devt_mutex);
}
}
@@ -473,7 +505,7 @@ struct gendisk *get_gendisk(dev_t devt, int *partno)
struct hd_struct *part;
mutex_lock(&ext_devt_mutex);
- part = idr_find(&ext_devt_idr, MINOR(devt));
+ part = idr_find(&ext_devt_idr, blk_mangle_minor(MINOR(devt)));
if (part && get_disk(part_to_disk(part))) {
*partno = part->partno;
disk = part_to_disk(part);
diff --git a/drivers/ide/ide-disk.c b/drivers/ide/ide-disk.c
index 7a88de9ada29..a072df5053ae 100644
--- a/drivers/ide/ide-disk.c
+++ b/drivers/ide/ide-disk.c
@@ -42,7 +42,13 @@
#include <asm/div64.h>
#define IDE_DISK_PARTS (1 << PARTN_BITS)
+
+#if !defined(CONFIG_DEBUG_BLOCK_EXT_DEVT)
#define IDE_DISK_MINORS IDE_DISK_PARTS
+#else
+#define IDE_DISK_MINORS 1
+#endif
+
#define IDE_DISK_EXT_MINORS (IDE_DISK_PARTS - IDE_DISK_MINORS)
struct ide_disk_obj {
diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index d1bb0e1d2d28..280d231a86ed 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -87,7 +87,13 @@ MODULE_ALIAS_SCSI_DEVICE(TYPE_MOD);
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 *);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 0b504814e378..5a536f703a83 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -624,6 +624,22 @@ config BACKTRACE_SELF_TEST
Say N if you are unsure.
+config DEBUG_BLOCK_EXT_DEVT
+ bool "Force extended block device numbers and spread them"
+ depends on DEBUG_KERNEL
+ depends on BLOCK
+ default y
+ help
+ Conventionally, block device numbers are allocated from
+ predetermined contiguous area. However, extended block area
+ may introduce non-contiguous block device numbers. This
+ option forces most block device numbers to be allocated from
+ the extended space and spreads them to discover kernel or
+ userland code paths which assume predetermined contiguous
+ device number allocation.
+
+ Say N if you are unsure.
+
config LKDTM
tristate "Linux Kernel Dump Test Tool Module"
depends on DEBUG_KERNEL