From 8892cbaf686fb18a5f0558b9fd7773b32c0c7852 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Thu, 26 May 2011 21:06:50 +0200 Subject: [PATCH] brd: export module parameters Export 'rd_nr', 'rd_size' and 'max_part' parameters to sysfs so user can know that how many devices are allowed, how big each device is and how many partitions are supported. If 'max_part' is 0, it means simply the device doesn't support partitioning. Also note that 'max_part' can be adjusted to power of 2 minus 1 form if needed. User should check this value after the module loading if he/she want to use that number correctly (i.e. fdisk, mknod, etc.). Signed-off-by: Namhyung Kim Cc: Laurent Vivier Signed-off-by: Jens Axboe --- drivers/block/brd.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/drivers/block/brd.c b/drivers/block/brd.c index d904d0da2928..dba1c32e1ddf 100644 --- a/drivers/block/brd.c +++ b/drivers/block/brd.c @@ -436,11 +436,11 @@ static int rd_nr; int rd_size = CONFIG_BLK_DEV_RAM_SIZE; static int max_part; static int part_shift; -module_param(rd_nr, int, 0); +module_param(rd_nr, int, S_IRUGO); MODULE_PARM_DESC(rd_nr, "Maximum number of brd devices"); -module_param(rd_size, int, 0); +module_param(rd_size, int, S_IRUGO); MODULE_PARM_DESC(rd_size, "Size of each RAM disk in kbytes."); -module_param(max_part, int, 0); +module_param(max_part, int, S_IRUGO); MODULE_PARM_DESC(max_part, "Maximum number of partitions per RAM disk"); MODULE_LICENSE("GPL"); MODULE_ALIAS_BLOCKDEV_MAJOR(RAMDISK_MAJOR); @@ -578,9 +578,20 @@ static int __init brd_init(void) */ part_shift = 0; - if (max_part > 0) + if (max_part > 0) { part_shift = fls(max_part); + /* + * Adjust max_part according to part_shift as it is exported + * to user space so that user can decide correct minor number + * if [s]he want to create more devices. + * + * Note that -1 is required because partition 0 is reserved + * for the whole disk. + */ + max_part = (1UL << part_shift) - 1; + } + if ((1UL << part_shift) > DISK_MAX_PARTS) return -EINVAL;