btrfs-progs: tests: add basic compression coverage

Create a source for --rootdir and then use it for mkfs with compression.
Try a few levels, nothing special.

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

tests/mkfs-tests/037-basic-compression/test.sh

@@ -0,0 +1,56 @@
+#!/bin/bash
+# Basic test for mkfs.btrfs --compress --rootdir. Create a dataset and use it
+# for filesystem creation with various compression levels.
+
+source "$TEST_TOP/common" || exit
+
+check_prereq mkfs.btrfs
+check_prereq btrfs
+check_global_prereq du
+
+setup_root_helper
+prepare_test_dev
+
+tmp=$(_mktemp_dir mkfs-rootdir)
+limit=$((128*1024*1024))
+
+# Create dataset of approximate size 256M so the repeated compression does not take that long
+for file in /usr/bin/[gx]*; do
+	run_check cp -axf --update --no-preserve=ownership,context "$file" "$tmp"
+	size=$(du -sb "$tmp" | awk '{print $1}')
+	if [ "$size" -gt "$limit" ]; then
+		break
+	fi
+done
+
+for file in /usr/lib*/lib[abcdef]*; do
+	run_check cp -axf --update --no-preserve=ownership,context "$file" "$tmp"
+	size=$(du -sb "$tmp" | awk '{print $1}')
+	if [ "$size" -gt "$limit" ]; then
+		break
+	fi
+done
+
+run_check du -sh "$tmp"
+
+run_test()
+{
+	local comp="$1"
+
+	run_check_mkfs_test_dev --rootdir "$tmp" --compress "$comp"
+	run_check $SUDO_HELPER "$TOP/btrfs" check "$TEST_DEV"
+
+	run_check_mount_test_dev
+	run_check du -sh "$TEST_MNT"
+	run_check_umount_test_dev
+}
+
+run_test lzo
+run_test zlib
+run_test zlib:1
+run_test zlib:9
+run_test zstd
+run_test zstd:1
+run_test zstd:15
+
+run_check rm -rf -- "$tmp"