mmc: make number of mmcblk minors configurable
The old limit of number of minor numbers per mmcblk device was hardcoded
at 8. This isn't enough for some of the more elaborate partitioning
schemes, for example those used by Chrome OS.
Since there might be a bunch of systems out there with static /dev
contents that relies on the old numbering scheme, let's make it a
build-time option with the default set to the previous 8.
Also provide a boot/modprobe-time parameter to override the config
default: mmcblk.perdev_minors.
Signed-off-by: Olof Johansson <olof@lixom.net>
Cc: Mandeep Baines <msb@chromium.org>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Chris Ball <cjb@laptop.org>
diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index a997050..217f820 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -43,15 +43,27 @@
#include "queue.h"
MODULE_ALIAS("mmc:block");
-
-/*
- * max 8 partitions per card
- */
-#define MMC_SHIFT 3
-#define MMC_NUM_MINORS (256 >> MMC_SHIFT)
+#ifdef MODULE_PARAM_PREFIX
+#undef MODULE_PARAM_PREFIX
+#endif
+#define MODULE_PARAM_PREFIX "mmcblk."
static DEFINE_MUTEX(block_mutex);
-static DECLARE_BITMAP(dev_use, MMC_NUM_MINORS);
+
+/*
+ * The defaults come from config options but can be overriden by module
+ * or bootarg options.
+ */
+static int perdev_minors = CONFIG_MMC_BLOCK_MINORS;
+
+/*
+ * We've only got one major, so number of mmcblk devices is
+ * limited to 256 / number of minors per device.
+ */
+static int max_devices;
+
+/* 256 minors, so at most 256 separate devices */
+static DECLARE_BITMAP(dev_use, 256);
/*
* There is one mmc_blk_data per slot.
@@ -67,6 +79,9 @@
static DEFINE_MUTEX(open_lock);
+module_param(perdev_minors, int, 0444);
+MODULE_PARM_DESC(perdev_minors, "Minors numbers to allocate per device");
+
static struct mmc_blk_data *mmc_blk_get(struct gendisk *disk)
{
struct mmc_blk_data *md;
@@ -88,10 +103,10 @@
md->usage--;
if (md->usage == 0) {
int devmaj = MAJOR(disk_devt(md->disk));
- int devidx = MINOR(disk_devt(md->disk)) >> MMC_SHIFT;
+ int devidx = MINOR(disk_devt(md->disk)) / perdev_minors;
if (!devmaj)
- devidx = md->disk->first_minor >> MMC_SHIFT;
+ devidx = md->disk->first_minor / perdev_minors;
blk_cleanup_queue(md->queue.queue);
@@ -566,8 +581,8 @@
struct mmc_blk_data *md;
int devidx, ret;
- devidx = find_first_zero_bit(dev_use, MMC_NUM_MINORS);
- if (devidx >= MMC_NUM_MINORS)
+ devidx = find_first_zero_bit(dev_use, max_devices);
+ if (devidx >= max_devices)
return ERR_PTR(-ENOSPC);
__set_bit(devidx, dev_use);
@@ -584,7 +599,7 @@
*/
md->read_only = mmc_blk_readonly(card);
- md->disk = alloc_disk(1 << MMC_SHIFT);
+ md->disk = alloc_disk(perdev_minors);
if (md->disk == NULL) {
ret = -ENOMEM;
goto err_kfree;
@@ -601,7 +616,7 @@
md->queue.data = md;
md->disk->major = MMC_BLOCK_MAJOR;
- md->disk->first_minor = devidx << MMC_SHIFT;
+ md->disk->first_minor = devidx * perdev_minors;
md->disk->fops = &mmc_bdops;
md->disk->private_data = md;
md->disk->queue = md->queue.queue;
@@ -670,7 +685,6 @@
{
struct mmc_blk_data *md;
int err;
-
char cap_str[10];
/*
@@ -760,6 +774,11 @@
{
int res;
+ if (perdev_minors != CONFIG_MMC_BLOCK_MINORS)
+ pr_info("mmcblk: using %d minors per device\n", perdev_minors);
+
+ max_devices = 256 / perdev_minors;
+
res = register_blkdev(MMC_BLOCK_MAJOR, "mmc");
if (res)
goto out;