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| author | Namhyung Kim <namhyung@gmail.com> | 2011-05-27 07:59:25 +0200 |
|---|---|---|
| committer | Jens Axboe <jaxboe@fusionio.com> | 2011-05-27 07:59:25 +0200 |
| commit | ac04fee0b5c55bbac0858727a4154110b55d3f5a (patch) | |
| tree | 5277380fe275b447ebe5f8d26762c34dea503cf5 /drivers/block | |
| parent | d86e0e83b32bc84600adb0b6ea1fce389b266682 (diff) | |
| download | lwn-ac04fee0b5c55bbac0858727a4154110b55d3f5a.tar.gz lwn-ac04fee0b5c55bbac0858727a4154110b55d3f5a.zip | |
loop: export module parameters
Export 'max_loop' and 'max_part' parameters to sysfs so user can know
that how many devices are allowed and how many partitions are supported.
If 'max_loop' is 0, there is no restriction on the number of loop devices.
User can create/use the devices as many as minor numbers available. 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 <namhyung@gmail.com>
Cc: Laurent Vivier <Laurent.Vivier@bull.net>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
Diffstat (limited to 'drivers/block')
| -rw-r--r-- | drivers/block/loop.c | 17 |
1 files changed, 14 insertions, 3 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index c59a672a3de0..76c8da78212b 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1540,9 +1540,9 @@ static const struct block_device_operations lo_fops = { * And now the modules code and kernel interface. */ static int max_loop; -module_param(max_loop, int, 0); +module_param(max_loop, int, S_IRUGO); MODULE_PARM_DESC(max_loop, "Maximum number of loop devices"); -module_param(max_part, int, 0); +module_param(max_part, int, S_IRUGO); MODULE_PARM_DESC(max_part, "Maximum number of partitions per loop device"); MODULE_LICENSE("GPL"); MODULE_ALIAS_BLOCKDEV_MAJOR(LOOP_MAJOR); @@ -1688,9 +1688,20 @@ static int __init loop_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; |