btrfs-progs: misc-tests: Superblock corruption and recovery using backup

Signed-off-by: Lakshmipathi.G <Lakshmipathi.G@giis.co.in>
Signed-off-by: David Sterba <dsterba@suse.com>

tests/misc-tests/020-fix-superblock-corruption/test.sh

@@ -0,0 +1,34 @@
+#!/bin/bash
+#
+# Corrupt primary superblock and restore it using backup superblock.
+
+source "$TOP/tests/common"
+
+check_prereq btrfs-select-super
+check_prereq btrfs
+
+setup_root_helper
+prepare_test_dev
+
+FIRST_SUPERBLOCK_OFFSET=65536
+
+test_superblock_restore()
+{
+	run_check $SUDO_HELPER "$TOP/mkfs.btrfs" -f "$TEST_DEV"
+
+	# Corrupt superblock checksum
+	run_check $SUDO_HELPER dd if=/dev/zero of="$TEST_DEV" \
+	seek="$FIRST_SUPERBLOCK_OFFSET" bs=1 count=4 conv=notrunc
+
+	# Run btrfs check to detect corruption
+	run_mayfail "$TOP/btrfs" check "$TEST_DEV" && \
+		_fail "btrfs check should detect corruption"
+
+	# Copy backup superblock to primary
+	run_check "$TOP/btrfs-select-super" -s 1 "$TEST_DEV"
+
+	# Perform btrfs check
+	run_check "$TOP/btrfs" check "$TEST_DEV"
+}
+
+test_superblock_restore