Btrfs-progs: fsck: add tests for extent tree rebuilding

We need test to verify extent tree rebuilding work, this test
create a strange filesystem with some snapshots, destroy
extent root node, and run fsck with "--init-extent-tree".

Since this tests need btrfs internal tool(btrfs-corrupt-block),so
i add this test into btrfs-progs.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

tests/fsck-tests.sh

@@ -6,27 +6,74 @@
 #
 
 here=`pwd`
+TEST_DEV=
+TEST_MNT=
+RESULT="fsck-tests-results.txt"
 
 _fail()
 {
-	echo "$*" | tee -a fsck-tests-results.txt
+	echo "$*" | tee -a $RESULT
 	exit 1
 }
 
-rm -f fsck-tests-results.txt
+run_check()
+{
+	echo "############### $@" >> $RESULT 2>&1
+	"$@" >> $RESULT 2>&1 || _fail "failed: $@"
+}
+
+rm -f $RESULT
+
+if [ -z $TEST_DEV ] || [ -z $TEST_MNT ];then
+	_fail "please set TEST_DEV and TEST_MNT"
+fi
+
+# test rely on corrupting blocks tool
+run_check make btrfs-corrupt-block
 
 for i in $(find $here/tests/fsck-tests -name '*.img')
 do
 	echo "     [TEST]    $(basename $i)"
-	echo "testing image $i" >> fsck-tests-results.txt
-	$here/btrfs-image -r $i test.img >> fsck-tests-results.txt 2>&1 \
-		|| _fail "restore failed"
-	$here/btrfsck test.img >> fsck-test-results.txt 2>&1
+	echo "testing image $i" >> $RESULT
+
+	run_check $here/btrfs-image -r $i test.img
+
+	$here/btrfsck test.img >> $RESULT 2>&1
 	[ $? -eq 0 ] && _fail "btrfsck should have detected corruption"
 
-	$here/btrfsck --repair test.img >> fsck-test-results.txt 2>&1 || \
-		_fail "btrfsck should have repaired the image"
-
-	$here/btrfsck test.img >> fsck-test-results.txt 2>&1 || \
-		_fail "btrfsck did not correct corruption"
+	run_check $here/btrfsck --repair test.img
+	run_check $here/btrfsck test.img
 done
+
+# test whether fsck can rebuild a corrupted extent tree
+test_extent_tree_rebuild()
+{
+	echo "     [TEST]    extent tree rebuild"
+	$here/mkfs.btrfs -f $TEST_DEV >> /dev/null 2>&1 || _fail "fail to mkfs"
+
+	run_check mount $TEST_DEV $TEST_MNT
+	cp -aR /lib/modules/`uname -r`/ $TEST_MNT 2>&1
+
+	for i in `seq 1 100`;do
+		$here/btrfs sub snapshot $TEST_MNT \
+			$TEST_MNT/snapaaaaaaa_$i >& /dev/null
+	done
+	run_check umount $TEST_DEV
+
+	# get extent root bytenr
+	extent_root_bytenr=`$here/btrfs-debug-tree -r $TEST_DEV | grep extent | awk '{print $7}'`
+	if [ -z $extent_root_bytenr ];then
+		_fail "fail to get extent root bytenr"
+	fi
+
+	# corrupt extent root node block
+	run_check $here/btrfs-corrupt-block -l $extent_root_bytenr \
+		-b 4096 $TEST_DEV
+
+	$here/btrfs check $TEST_DEV >& /dev/null && \
+			_fail "fsck should detect failure"
+	run_check $here/btrfs check --init-extent-tree $TEST_DEV
+	run_check $here/btrfs check $TEST_DEV
+}
+
+test_extent_tree_rebuild