btrfs-progs: tests: Test for FST corruption detection/repair

Simple test case which preps a filesystem, then corrupts the FST and
finally repairs it. Tests both extent based and bitmap based FSTs.

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

tests/fsck-tests/037-freespacetree-repair/test.sh

@@ -0,0 +1,76 @@
+#!/bin/bash
+# Corrupt a filesystem that is using freespace tree and then ensure that
+# btrfs check is able to repair it. This tests correct detection/repair of
+# both a FREE_SPACE_EXTENT based FST and a FREE_SPACE_BITMAP based FST.
+
+source "$TEST_TOP/common"
+
+setup_root_helper
+prepare_test_dev 256M
+
+check_prereq btrfs
+check_prereq mkfs.btrfs
+check_global_prereq grep
+check_global_prereq tail
+check_global_prereq head
+check_global_prereq cut
+
+# wrapper for btrfs-corrupt-item
+# $1: Type of item we want to corrupt - extent or bitmap
+corrupt_fst_item()
+{
+	local type
+	local objectid
+	local offset
+	type="$1"
+
+	if [[ $type == "bitmap" ]]; then
+		type=200
+		objectid=$("$TOP/btrfs" inspect-internal dump-tree -t 10 "$TEST_DEV" | \
+			grep -o "[[:digit:]]* FREE_SPACE_BITMAP [[:digit:]]*" | \
+			cut -d' ' -f1 | tail -2 | head -1)
+		offset=$("$TOP/btrfs" inspect-internal dump-tree -t 10 "$TEST_DEV" | \
+			grep -o "[[:digit:]]* FREE_SPACE_BITMAP [[:digit:]]*" | \
+			cut -d' ' -f3 | tail -2 | head -1)
+		echo "Corrupting $objectid,FREE_SPACE_BITMAP,$offset" >> "$RESULTS"
+	elif [[ $type == "extent" ]]; then
+		type=199
+		objectid=$("$TOP/btrfs" inspect-internal dump-tree -t 10 "$TEST_DEV" | \
+			grep -o "[[:digit:]]* FREE_SPACE_EXTENT [[:digit:]]*" | \
+			cut -d' ' -f1 | tail -2 | head -1)
+		offset=$("$TOP/btrfs" inspect-internal dump-tree -t 10 "$TEST_DEV" | \
+			grep -o "[[:digit:]]* FREE_SPACE_EXTENT [[:digit:]]*" | \
+			cut -d' ' -f3 | tail -2 | head -1)
+		echo "Corrupting $objectid,FREE_SPACE_EXTENT,$offset" >> "$RESULTS"
+	else
+		_fail "Unknown item type for corruption"
+	fi
+
+	run_check "$TOP/btrfs-corrupt-block" -r 10 -K "$objectid,$type,$offset" \
+		-f offset "$TEST_DEV"
+}
+
+run_check "$TOP/mkfs.btrfs" -n 4k -f "$TEST_DEV"
+run_check_mount_test_dev -oclear_cache,space_cache=v2
+
+# create files which will populate the FST
+for i in {1..3000}; do
+	run_check $SUDO_HELPER fallocate -l 4k "$TEST_MNT/file.$i"
+done
+
+run_check_umount_test_dev
+
+# now corrupt one of the bitmap items
+corrupt_fst_item "bitmap"
+check_image "$TEST_DEV"
+
+# change the freespace such that we now have at least one free_space_extent
+# object
+run_check_mount_test_dev
+rm -rf "$TEST_MNT/file.*"
+run_check $SUDO_HELPER fallocate -l 50m "$TEST_MNT/file"
+run_check_umount_test_dev
+
+# now corrupt an extent
+corrupt_fst_item "extent"
+check_image "$TEST_DEV"