loop: add BLK_DEV_LOOP_MIN_COUNT=%i to allow distros 0 pre-allocated loop devices

Instead of unconditionally creating a fixed number of dead loop
devices which need to be investigated by storage handling services,
even when they are never used, we allow distros start with 0
loop devices and have losetup(8) and similar switch to the dynamic
/dev/loop-control interface instead of searching /dev/loop%i for free
devices.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index 717d6e4e18d3..57212c5235e2 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -256,6 +256,21 @@ config BLK_DEV_LOOP
 
           Most users will answer N here.
 
+config BLK_DEV_LOOP_MIN_COUNT
+        int "Number of loop devices to pre-create at init time"
+        depends on BLK_DEV_LOOP
+        default 8
+        help
+          Static number of loop devices to be unconditionally pre-created
+          at init time.
+
+          This default value can be overwritten on the kernel command
+          line or with module-parameter loop.max_loop.
+
+          The historic default is 8. If a late 2011 version of losetup(8)
+          is used, it can be set to 0, since needed loop devices can be
+          dynamically allocated with the /dev/loop-control interface.
+
 config BLK_DEV_CRYPTOLOOP
         tristate "Cryptoloop Support"
         select CRYPTO