btrfs/081: declare local variables as local

Some variables inside the test's functions were used as local but
were not being declared as such. Add the local declaration for them.

Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>

tests/btrfs/081

@@ -45,7 +45,7 @@ extent_size=8192
 
 create_source_file()
 {
-	name=$1
+	local name=$1
 
 	# Create a file with $num_extents extents, each with a size of
 	# $extent_size bytes.
@@ -60,8 +60,8 @@ create_source_file()
 
 create_target_file()
 {
-	name=$1
-	file_size=$(($num_extents * $extent_size))
+	local name=$1
+	local file_size=$(($num_extents * $extent_size))
 
 	$XFS_IO_PROG -f -c "pwrite -S 0xff 0 $file_size" \
 		-c "fsync" $SCRATCH_MNT/$name | _filter_xfs_io
@@ -69,7 +69,7 @@ create_target_file()
 
 reader_loop()
 {
-	name=$1
+	local name=$1
 
 	while true; do
 		cat $SCRATCH_MNT/$name > /dev/null