Avoid block device autoloading warning.

It's possible to trigger the block device autoloading mechanism
with a mknod()/stat(), and this mechanism has long been declared
obsolete, thus triggering a dmesg warning since el9_7, which then
fails the test. You may need to `rmmod loop` to reproduce.

Avoid this by avoiding to trigger a loop autoload - we just make a
different blockdev. Chosing `42` here should avoid any autoload
mechanism as this number is explicitly for demo drivers and should
never trigger an autoload.

We also just ignore the warning line in dmesg. Other tests can and
might perhaps still trigger this, as well as background noise running
during the test.

Signed-off-by: Auke Kok <auke.kok@versity.com>

tests/funcs/filter.sh

@@ -170,6 +170,9 @@ t_filter_dmesg()
 	# some ci test guests are unresponsive
 	re="$re|longest quorum heartbeat .* delay"
 
+	# creating block devices may trigger this
+	re="$re|block device autoloading is deprecated and will be removed."
+
 	egrep -v "($re)" | \
 		ignore_harmless_unwind_kasan_stack_oob
 }

tests/tests/get-referring-entries.sh

@@ -72,7 +72,7 @@ touch $T_D0/dir/file
 mkdir $T_D0/dir/dir
 ln -s $T_D0/dir/file $T_D0/dir/symlink
 mknod $T_D0/dir/char c 1 3 # null
-mknod $T_D0/dir/block b 7 0 # loop0
+mknod $T_D0/dir/block b 42 0 # SAMPLE block dev - nonexistant/demo use only number
 for name in $(ls -UA $T_D0/dir | sort); do
 	ino=$(stat -c '%i' $T_D0/dir/$name)
 	$GRE $ino | filter_types