btrfs-progs: corrupt btrfs items in btrfs-corrup-block

For testing fsck against completely broken btrfs_items.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

btrfs-corrupt-block.c

@@ -108,6 +108,8 @@ static void print_usage(void)
 	fprintf(stderr, "\t-K The key to corrupt in the format "
 		"<num>,<num>,<num> (must also specify -f for the field)\n");
 	fprintf(stderr, "\t-f The field in the item to corrupt\n");
+	fprintf(stderr, "\t-I An item to corrupt (must also specify the field "
+		"to corrupt and a root+key for the item)\n");
 	fprintf(stderr, "\t-D Corrupt a dir item, must specify key and field\n");
 	exit(1);
 }
@@ -313,6 +315,11 @@ enum btrfs_metadata_block_field {
 	BTRFS_METADATA_BLOCK_BAD,
 };
 
+enum btrfs_item_field {
+	BTRFS_ITEM_OFFSET,
+	BTRFS_ITEM_BAD,
+};
+
 enum btrfs_key_field {
 	BTRFS_KEY_OBJECTID,
 	BTRFS_KEY_TYPE,
@@ -353,6 +360,13 @@ static enum btrfs_key_field convert_key_field(char *field)
 	return BTRFS_KEY_BAD;
 }
 
+static enum btrfs_item_field convert_item_field(char *field)
+{
+	if (!strncmp(field, "offset", FIELD_BUF_LEN))
+		return BTRFS_ITEM_OFFSET;
+	return BTRFS_ITEM_BAD;
+}
+
 static enum btrfs_dir_item_field convert_dir_item_field(char *field)
 {
 	if (!strncmp(field, "name", FIELD_BUF_LEN))
@@ -371,6 +385,15 @@ static u64 generate_u64(u64 orig)
 	return ret;
 }
 
+static u32 generate_u32(u32 orig)
+{
+	u32 ret;
+	do {
+		ret = rand();
+	} while (ret == orig);
+	return ret;
+}
+
 static u8 generate_u8(u8 orig)
 {
 	u8 ret;
@@ -709,6 +732,58 @@ out:
 	return ret;
 }
 
+static int corrupt_btrfs_item(struct btrfs_root *root, struct btrfs_key *key,
+			      char *field)
+{
+	struct btrfs_trans_handle *trans;
+	struct btrfs_path *path;
+	enum btrfs_item_field corrupt_field;
+	u32 orig, bogus;
+	int ret;
+
+	corrupt_field = convert_item_field(field);
+	if (corrupt_field == BTRFS_ITEM_BAD) {
+		fprintf(stderr, "Invalid field %s\n", field);
+		return -EINVAL;
+	}
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	trans = btrfs_start_transaction(root, 1);
+	if (IS_ERR(trans)) {
+		btrfs_free_path(path);
+		fprintf(stderr, "Couldn't start transaction %ld\n",
+			PTR_ERR(trans));
+		return PTR_ERR(trans);
+	}
+
+	ret = btrfs_search_slot(trans, root, key, path, 0, 1);
+	if (ret != 0) {
+		fprintf(stderr, "Error searching to node %d\n", ret);
+		goto out;
+	}
+
+	ret = 0;
+	switch (corrupt_field) {
+	case BTRFS_ITEM_OFFSET:
+		orig = btrfs_item_offset_nr(path->nodes[0], path->slots[0]);
+		bogus = generate_u32(orig);
+		btrfs_set_item_offset(path->nodes[0],
+				      btrfs_item_nr(path->slots[0]), bogus);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	btrfs_mark_buffer_dirty(path->nodes[0]);
+out:
+	btrfs_commit_transaction(trans, root);
+	btrfs_free_path(path);
+	return ret;
+}
+
 static struct option long_options[] = {
 	/* { "byte-count", 1, NULL, 'b' }, */
 	{ "logical", 1, NULL, 'l' },
@@ -724,6 +799,7 @@ static struct option long_options[] = {
 	{ "metadata-block", 1, NULL, 'm'},
 	{ "field", 1, NULL, 'f'},
 	{ "key", 1, NULL, 'K'},
+	{ "item", 0, NULL, 'I'},
 	{ "dir-item", 0, NULL, 'D'},
 	{ 0, 0, 0, 0}
 };
@@ -888,6 +964,7 @@ int main(int ac, char **av)
 	int corrupt_block_keys = 0;
 	int chunk_rec = 0;
 	int chunk_tree = 0;
+	int corrupt_item = 0;
 	int corrupt_di = 0;
 	u64 metadata_block = 0;
 	u64 inode = 0;
@@ -900,7 +977,7 @@ int main(int ac, char **av)
 
 	while(1) {
 		int c;
-		c = getopt_long(ac, av, "l:c:b:eEkuUi:f:x:m:K:D", long_options,
+		c = getopt_long(ac, av, "l:c:b:eEkuUi:f:x:m:K:ID", long_options,
 				&option_index);
 		if (c < 0)
 			break;
@@ -954,6 +1031,9 @@ int main(int ac, char **av)
 			case 'D':
 				corrupt_di = 1;
 				break;
+			case 'I':
+				corrupt_item = 1;
+				break;
 			default:
 				print_usage();
 		}
@@ -1056,6 +1136,12 @@ int main(int ac, char **av)
 		ret = corrupt_dir_item(root, &key, field);
 		goto out_close;
 	}
+	if (corrupt_item) {
+		if (!key.objectid)
+			print_usage();
+		ret = corrupt_btrfs_item(root, &key, field);
+		goto out_close;
+	}
 	if (key.objectid || key.offset || key.type) {
 		if (!strlen(field))
 			print_usage();