mount,losetup: use /dev/loop-control is it exists

function                                             old     new   delta
get_free_loop                                          -      58     +58
set_loop                                             597     649     +52
losetup_main                                         482     476      -6
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/1 up/down: 110/-6)            Total: 104 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/util-linux/losetup.c b/util-linux/losetup.c
index b52d693ec..5dc757074 100644
--- a/util-linux/losetup.c
+++ b/util-linux/losetup.c
@@ -114,8 +114,14 @@ int losetup_main(int argc UNUSED_PARAM, char **argv)
         /* contains -f */
         if (opt & OPT_f) {
                 char *s;
-                int n = 0;
+                int n;
 
+                n = get_free_loop();
+                if (n == -1)
+                        bb_error_msg_and_die("no free loop devices");
+                if (n < 0) /* n == -2: no /dev/loop-control, use legacy method */
+                        n = 0;
+                /* or: n >= 0: the number of next free loopdev, just verify it */
                 do {
                         if (n > MAX_LOOP_NUM)
                                 bb_error_msg_and_die("no free loop devices");