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, 6 insertions, 3 deletions

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 4ca93898fbd3..c32851131646 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1340,9 +1340,12 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
                         it is equivalent to "nosmp", which also disables
                         the IO APIC.
 
-        max_loop=       [LOOP] Maximum number of loopback devices that can
-                        be mounted
-                        Format: <1-256>
+        max_loop=       [LOOP] The number of loop block devices that get
+        (loop.max_loop) unconditionally pre-created at init time. The default
+                        number is configured by BLK_DEV_LOOP_MIN_COUNT. Instead
+                        of statically allocating a predefined number, loop
+                        devices can be requested on-demand with the
+                        /dev/loop-control interface.
 
         mcatest=        [IA-64]