btrfs-progs: tests: truncate test image to 0 first

We use the prepare_test_dev helper to make sure the image has at least
this size. The "at least" part is not desired by some tests as the
device might be larger than the test expects.

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/tests/common b/tests/common
index a2e2f50..2fac202 100644 (file)
--- a/tests/common
+++ b/tests/common
@@ -444,6 +444,7 @@ prepare_test_dev()
        [[ "$size" ]] || size='2G'
        # Still truncate it to new size
        if [ -n "$TEST_DEV" ]; then
+               truncate -s 0 "$TEST_DEV"
                truncate -s "$size" "$TEST_DEV"
                return;
        fi
@@ -452,6 +453,7 @@ prepare_test_dev()
                "$RESULTS"
        TEST_DEV="$TOP/tests/test.img"
 
+       truncate -s 0 "$TEST_DEV"
        truncate -s "$size" "$TEST_DEV" || _not_run "create file for loop device failed"
 }