+ mmc-add-config-and-runtime-option-for-number-of-mmcblk-minors.patch added to -mm tree

Commit Message

Andrew Morton Aug. 20, 2010, 1:15 a.m. UTC

None

Patch

diff -puN drivers/mmc/card/Kconfig~mmc-add-config-and-runtime-option-for-number-of-mmcblk-minors drivers/mmc/card/Kconfig
--- a/drivers/mmc/card/Kconfig~mmc-add-config-and-runtime-option-for-number-of-mmcblk-minors
+++ a/drivers/mmc/card/Kconfig
@@ -14,6 +14,23 @@  config MMC_BLOCK
 	  mount the filesystem. Almost everyone wishing MMC support
 	  should say Y or M here.
 
+config MMC_BLOCK_MINORS
+	int "Number of minors per block device"
+	range 4 256
+	default 8
+	help
+	  Number of minors per block device. One is needed for every
+	  partition on the disk (plus one for the whole disk).
+
+	  Number of total MMC minors available is 256, so your number
+	  of supported block devices will be limited to 256 divided
+	  by this number.
+
+	  Default is 8 to be backwards compatible with previous
+	  hardwired device numbering.
+
+	  If unsure, say 8 here.
+
 config MMC_BLOCK_BOUNCE
 	bool "Use bounce buffer for simple hosts"
 	depends on MMC_BLOCK
diff -puN drivers/mmc/card/block.c~mmc-add-config-and-runtime-option-for-number-of-mmcblk-minors drivers/mmc/card/block.c
--- a/drivers/mmc/card/block.c~mmc-add-config-and-runtime-option-for-number-of-mmcblk-minors
+++ a/drivers/mmc/card/block.c
@@ -44,14 +44,26 @@ 
 #include "queue.h"
 
 MODULE_ALIAS("mmc:block");
+#ifdef MODULE_PARAM_PREFIX
+#undef MODULE_PARAM_PREFIX
+#endif
+#define MODULE_PARAM_PREFIX "mmcblk."
+
+
+/*
+ * The defaults come from config options but can be overriden by module
+ * or bootarg options.
+ */
+static int perdev_minors = CONFIG_MMC_BLOCK_MINORS;
 
 /*
- * max 8 partitions per card
+ * We've only got one major, so number of mmcblk devices is
+ * limited to 256 / number of minors per device.
  */
-#define MMC_SHIFT	3
-#define MMC_NUM_MINORS	(256 >> MMC_SHIFT)
+static int max_devices = DIV_ROUND_UP(256, CONFIG_MMC_BLOCK_MINORS);
 
-static DECLARE_BITMAP(dev_use, MMC_NUM_MINORS);
+/* 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 @@  struct mmc_blk_data {
 
 static DEFINE_MUTEX(open_lock);
 
+module_param(perdev_minors, int, 0644);
+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 @@  static void mmc_blk_put(struct mmc_blk_d
 	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);
 
@@ -567,8 +582,8 @@  static struct mmc_blk_data *mmc_blk_allo
 	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);
 
@@ -585,7 +600,7 @@  static struct mmc_blk_data *mmc_blk_allo
 	 */
 	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;
@@ -602,7 +617,7 @@  static struct mmc_blk_data *mmc_blk_allo
 	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;
@@ -678,7 +693,6 @@  static int mmc_blk_probe(struct mmc_card
 {
 	struct mmc_blk_data *md;
 	int err;
-
 	char cap_str[10];
 
 	/*
@@ -768,6 +782,11 @@  static int __init mmc_blk_init(void)
 {
 	int res;
 
+	if (perdev_minors != CONFIG_MMC_BLOCK_MINORS) {
+		pr_info("mmcblk: using %d minors per device\n", perdev_minors);
+		max_devices = DIV_ROUND_UP(256, perdev_minors);
+	}
+
 	res = register_blkdev(MMC_BLOCK_MAJOR, "mmc");
 	if (res)
 		goto out;