btrfs: selftests: dump extent io tree if extent-io-tree test failed

When code modifying extent-io-tree get modified and got that selftest
failed, it can take some time to pin down the cause.

To make it easier to expose the problem, dump the extent io tree if the
selftest failed.

This can save developers debug time, especially since the selftest we
can not use the trace events, thus have to manually add debug trace
points.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/tests/extent-io-tests.c

@@ -56,6 +56,54 @@ static noinline int process_page_range(struct inode *inode, u64 start, u64 end,
 	return count;
 }
 
+#define STATE_FLAG_STR_LEN			256
+
+#define PRINT_ONE_FLAG(state, dest, cur, name)				\
+({									\
+	if (state->state & EXTENT_##name)				\
+		cur += scnprintf(dest + cur, STATE_FLAG_STR_LEN - cur,	\
+				 "%s" #name, cur == 0 ? "" : "|");	\
+})
+
+static void extent_flag_to_str(const struct extent_state *state, char *dest)
+{
+	int cur = 0;
+
+	dest[0] = 0;
+	PRINT_ONE_FLAG(state, dest, cur, DIRTY);
+	PRINT_ONE_FLAG(state, dest, cur, UPTODATE);
+	PRINT_ONE_FLAG(state, dest, cur, LOCKED);
+	PRINT_ONE_FLAG(state, dest, cur, NEW);
+	PRINT_ONE_FLAG(state, dest, cur, DELALLOC);
+	PRINT_ONE_FLAG(state, dest, cur, DEFRAG);
+	PRINT_ONE_FLAG(state, dest, cur, BOUNDARY);
+	PRINT_ONE_FLAG(state, dest, cur, NODATASUM);
+	PRINT_ONE_FLAG(state, dest, cur, CLEAR_META_RESV);
+	PRINT_ONE_FLAG(state, dest, cur, NEED_WAIT);
+	PRINT_ONE_FLAG(state, dest, cur, DAMAGED);
+	PRINT_ONE_FLAG(state, dest, cur, NORESERVE);
+	PRINT_ONE_FLAG(state, dest, cur, QGROUP_RESERVED);
+	PRINT_ONE_FLAG(state, dest, cur, CLEAR_DATA_RESV);
+}
+
+static void dump_extent_io_tree(const struct extent_io_tree *tree)
+{
+	struct rb_node *node;
+	char flags_str[STATE_FLAG_STR_LEN];
+
+	node = rb_first(&tree->state);
+	test_msg("io tree content:");
+	while (node) {
+		struct extent_state *state;
+
+		state = rb_entry(node, struct extent_state, rb_node);
+		extent_flag_to_str(state, flags_str);
+		test_msg("  start=%llu len=%llu flags=%s", state->start,
+			 state->end + 1 - state->start, flags_str);
+		node = rb_next(node);
+	}
+}
+
 static int test_find_delalloc(u32 sectorsize)
 {
 	struct inode *inode;
@@ -258,6 +306,8 @@ static int test_find_delalloc(u32 sectorsize)
 	}
 	ret = 0;
 out_bits:
+	if (ret)
+		dump_extent_io_tree(tmp);
 	clear_extent_bits(tmp, 0, total_dirty - 1, (unsigned)-1);
 out:
 	if (locked_page)
@@ -534,6 +584,8 @@ static int test_find_first_clear_extent_bit(void)
 
 	ret = 0;
 out:
+	if (ret)
+		dump_extent_io_tree(&tree);
 	clear_extent_bits(&tree, 0, (u64)-1, CHUNK_TRIMMED | CHUNK_ALLOCATED);
 
 	return ret;