diff --git a/src/director/director-test.c b/src/director/director-test.c
index 7bc44e2465..ddcc4d024a 100644
--- a/src/director/director-test.c
+++ b/src/director/director-test.c
@@ -293,7 +293,7 @@ director_connection_input(struct director_connection *conn,
 	const unsigned char *data;
 	size_t size;
 
-	if (i_stream_read_data(input, &data, &size, 0) == -1) {
+	if (i_stream_read_more(input, &data, &size) == -1) {
 		director_connection_destroy(&conn);
 		return;
 	}
diff --git a/src/doveadm/doveadm-fs.c b/src/doveadm/doveadm-fs.c
index fec6da9077..51f9f99fa8 100644
--- a/src/doveadm/doveadm-fs.c
+++ b/src/doveadm/doveadm-fs.c
@@ -70,7 +70,7 @@ static void cmd_fs_get(int argc, char *argv[])
 
 	file = fs_file_init(fs, argv[0], FS_OPEN_MODE_READONLY);
 	input = fs_read_stream(file, IO_BLOCK_SIZE);
-	while ((ret = i_stream_read_data(input, &data, &size, 0)) > 0) {
+	while ((ret = i_stream_read_more(input, &data, &size)) > 0) {
 		doveadm_print_stream(data, size);
 		i_stream_skip(input, size);
 	}
diff --git a/src/doveadm/doveadm-print.c b/src/doveadm/doveadm-print.c
index 5f239148e6..08e1f8f90b 100644
--- a/src/doveadm/doveadm-print.c
+++ b/src/doveadm/doveadm-print.c
@@ -110,7 +110,7 @@ int doveadm_print_istream(struct istream *input)
 	size_t size;
 	ssize_t ret;
 
-	while ((ret = i_stream_read_data(input, &data, &size, 0)) > 0) {
+	while ((ret = i_stream_read_more(input, &data, &size)) > 0) {
 		doveadm_print_stream(data, size);
 		i_stream_skip(input, size);
 	}
diff --git a/src/doveadm/doveadm-zlib.c b/src/doveadm/doveadm-zlib.c
index a459a46058..957d4dd42d 100644
--- a/src/doveadm/doveadm-zlib.c
+++ b/src/doveadm/doveadm-zlib.c
@@ -69,7 +69,7 @@ static void cmd_dump_imapzlib(int argc ATTR_UNUSED, char *argv[])
 	input2 = i_stream_create_deflate(input, TRUE);
 	i_stream_unref(&input);
 
-	while (i_stream_read_data(input2, &data, &size, 0) != -1) {
+	while (i_stream_read_more(input2, &data, &size) != -1) {
 		fwrite(data, 1, size, stdout);
 		i_stream_skip(input2, size);
 	}
diff --git a/src/doveadm/dsync/dsync-mail.c b/src/doveadm/dsync/dsync-mail.c
index 0d5ce53dbf..f9fcb60384 100644
--- a/src/doveadm/dsync/dsync-mail.c
+++ b/src/doveadm/dsync/dsync-mail.c
@@ -46,7 +46,7 @@ int dsync_mail_get_hdr_hash(struct mail *mail, unsigned int version,
 
 	md5_init(&md5_ctx);
 	while (!i_stream_is_eof(input)) {
-		if (i_stream_read_data(input, &data, &size, 0) == -1)
+		if (i_stream_read_more(input, &data, &size) == -1)
 			break;
 		if (size == 0)
 			break;
diff --git a/src/doveadm/dsync/dsync-mailbox-import.c b/src/doveadm/dsync/dsync-mailbox-import.c
index 21e6acdaad..c82da81f23 100644
--- a/src/doveadm/dsync/dsync-mailbox-import.c
+++ b/src/doveadm/dsync/dsync-mailbox-import.c
@@ -359,8 +359,8 @@ dsync_istreams_cmp(struct istream *input1, struct istream *input2, int *cmp_r)
 	*cmp_r = -1; /* quiet gcc */
 
 	for (;;) {
-		(void)i_stream_read_data(input1, &data1, &size1, 0);
-		(void)i_stream_read_data(input2, &data2, &size2, 0);
+		(void)i_stream_read_more(input1, &data1, &size1);
+		(void)i_stream_read_more(input2, &data2, &size2);
 
 		if (size1 == 0 || size2 == 0)
 			break;
diff --git a/src/imap-urlauth/imap-urlauth-worker.c b/src/imap-urlauth/imap-urlauth-worker.c
index 84f80d33c6..b61da90722 100644
--- a/src/imap-urlauth/imap-urlauth-worker.c
+++ b/src/imap-urlauth/imap-urlauth-worker.c
@@ -280,7 +280,7 @@ static int client_run_url(struct client *client)
 	size_t size;
 	ssize_t ret = 0;
 
-	while (i_stream_read_data(client->msg_part_input, &data, &size, 0) > 0) {
+	while (i_stream_read_more(client->msg_part_input, &data, &size) > 0) {
 		if ((ret = o_stream_send(client->output, data, size)) < 0)
 			break;
 		i_stream_skip(client->msg_part_input, ret);
diff --git a/src/imap/cmd-setmetadata.c b/src/imap/cmd-setmetadata.c
index b8a6aaf1f3..bd18498e86 100644
--- a/src/imap/cmd-setmetadata.c
+++ b/src/imap/cmd-setmetadata.c
@@ -121,7 +121,7 @@ cmd_setmetadata_entry_read_stream(struct imap_setmetadata_context *ctx)
 	struct mail_attribute_value value;
 	int ret;
 
-	while ((ret = i_stream_read_data(ctx->input, &data, &size, 0)) > 0)
+	while ((ret = i_stream_read_more(ctx->input, &data, &size)) > 0)
 		i_stream_skip(ctx->input, size);
 	if (ctx->input->v_offset == ctx->entry_value_len) {
 		/* finished reading the value */
diff --git a/src/lda/main.c b/src/lda/main.c
index 8351860e34..55f963f5b8 100644
--- a/src/lda/main.c
+++ b/src/lda/main.c
@@ -127,7 +127,7 @@ create_raw_stream(struct mail_deliver_context *ctx,
 	if (ret > 0 && size >= 5 && memcmp(data, "From ", 5) == 0) {
 		/* skip until the first LF */
 		i_stream_skip(input, 5);
-		while (i_stream_read_data(input, &data, &size, 0) > 0) {
+		while (i_stream_read_more(input, &data, &size) > 0) {
 			for (i = 0; i < size; i++) {
 				if (data[i] == '\n')
 					break;
diff --git a/src/lib-compression/istream-bzlib.c b/src/lib-compression/istream-bzlib.c
index b8d0dff86c..5d1aabfb04 100644
--- a/src/lib-compression/istream-bzlib.c
+++ b/src/lib-compression/istream-bzlib.c
@@ -101,7 +101,7 @@ static ssize_t i_stream_bzlib_read(struct istream_private *stream)
 		}
 	}
 
-	if (i_stream_read_data(stream->parent, &data, &size, 0) < 0) {
+	if (i_stream_read_more(stream->parent, &data, &size) < 0) {
 		if (stream->parent->stream_errno != 0) {
 			stream->istream.stream_errno =
 				stream->parent->stream_errno;
diff --git a/src/lib-compression/istream-lzma.c b/src/lib-compression/istream-lzma.c
index 865a7819d5..bf6d5b344e 100644
--- a/src/lib-compression/istream-lzma.c
+++ b/src/lib-compression/istream-lzma.c
@@ -110,7 +110,7 @@ static ssize_t i_stream_lzma_read(struct istream_private *stream)
 		}
 	}
 
-	if (i_stream_read_data(stream->parent, &data, &size, 0) < 0) {
+	if (i_stream_read_more(stream->parent, &data, &size) < 0) {
 		if (stream->parent->stream_errno != 0) {
 			stream->istream.stream_errno =
 				stream->parent->stream_errno;
diff --git a/src/lib-compression/istream-zlib.c b/src/lib-compression/istream-zlib.c
index d212a20ce2..f90e195517 100644
--- a/src/lib-compression/istream-zlib.c
+++ b/src/lib-compression/istream-zlib.c
@@ -245,7 +245,7 @@ static ssize_t i_stream_zlib_read(struct istream_private *stream)
 		}
 	}
 
-	if (i_stream_read_data(stream->parent, &data, &size, 0) < 0) {
+	if (i_stream_read_more(stream->parent, &data, &size) < 0) {
 		if (stream->parent->stream_errno != 0) {
 			stream->istream.stream_errno =
 				stream->parent->stream_errno;
diff --git a/src/lib-compression/test-compression.c b/src/lib-compression/test-compression.c
index b84a06dea0..320d6b83ba 100644
--- a/src/lib-compression/test-compression.c
+++ b/src/lib-compression/test-compression.c
@@ -69,7 +69,7 @@ static void test_compression_handler(const struct compression_handler *handler)
 	sha1_init(&sha1);
 	file_input = i_stream_create_fd(fd, IO_BLOCK_SIZE, FALSE);
 	input = handler->create_istream(file_input, FALSE);
-	while ((ret = i_stream_read_data(input, &data, &size, 0)) > 0) {
+	while ((ret = i_stream_read_more(input, &data, &size)) > 0) {
 		sha1_loop(&sha1, data, size);
 		i_stream_skip(input, size);
 	}
@@ -124,7 +124,7 @@ static void test_compress_file(const char *in_path, const char *out_path)
 	file_output = o_stream_create_fd_file(fd_out, 0, FALSE);
 	output = handler->create_ostream(file_output, 1);
 	input = i_stream_create_fd_autoclose(&fd_in, IO_BLOCK_SIZE);
-	while (i_stream_read_data(input, &data, &size, 0) > 0) {
+	while (i_stream_read_more(input, &data, &size) > 0) {
 		sha1_loop(&sha1, data, size);
 		o_stream_nsend(output, data, size);
 		i_stream_skip(input, size);
@@ -142,7 +142,7 @@ static void test_compress_file(const char *in_path, const char *out_path)
 	sha1_init(&sha1);
 	file_input = i_stream_create_fd(fd_out, IO_BLOCK_SIZE, FALSE);
 	input = handler->create_istream(file_input, FALSE);
-	while ((ret = i_stream_read_data(input, &data, &size, 0)) > 0) {
+	while ((ret = i_stream_read_more(input, &data, &size)) > 0) {
 		sha1_loop(&sha1, data, size);
 		i_stream_skip(input, size);
 	}
diff --git a/src/lib-dict-extra/dict-fs.c b/src/lib-dict-extra/dict-fs.c
index 7b5ff9ca92..bc27e9f957 100644
--- a/src/lib-dict-extra/dict-fs.c
+++ b/src/lib-dict-extra/dict-fs.c
@@ -97,7 +97,7 @@ static int fs_dict_lookup(struct dict *_dict, pool_t pool, const char *key,
 	i_stream_read(input);
 
 	str = str_new(pool, i_stream_get_data_size(input)+1);
-	while ((ret = i_stream_read_data(input, &data, &size, 0)) > 0) {
+	while ((ret = i_stream_read_more(input, &data, &size)) > 0) {
 		str_append_n(str, data, size);
 		i_stream_skip(input, size);
 	}
diff --git a/src/lib-fs/fs-api.c b/src/lib-fs/fs-api.c
index af3657beca..1966ddd729 100644
--- a/src/lib-fs/fs-api.c
+++ b/src/lib-fs/fs-api.c
@@ -564,7 +564,7 @@ struct istream *fs_read_stream(struct fs_file *file, size_t max_buffer_size)
 
 	if ((file->flags & FS_OPEN_FLAG_ASYNC) == 0 && !input->blocking) {
 		/* read the whole input stream before returning */
-		while ((ret = i_stream_read_data(input, &data, &size, 0)) >= 0) {
+		while ((ret = i_stream_read_more(input, &data, &size)) >= 0) {
 			i_stream_skip(input, size);
 			if (ret == 0) {
 				if (fs_wait_async(file->fs) < 0) {
diff --git a/src/lib-http/http-message-parser.c b/src/lib-http/http-message-parser.c
index b0e1724075..272e72e2d8 100644
--- a/src/lib-http/http-message-parser.c
+++ b/src/lib-http/http-message-parser.c
@@ -104,7 +104,7 @@ int http_message_parse_finish_payload(struct http_message_parser *parser)
 	if (parser->payload == NULL)
 		return 1;
 
-	while ((ret = i_stream_read_data(parser->payload, &data, &size, 0)) > 0)
+	while ((ret = i_stream_read_more(parser->payload, &data, &size)) > 0)
 		i_stream_skip(parser->payload, size);
 	if (ret == 0 || parser->payload->stream_errno != 0) {
 		if (ret < 0) {
diff --git a/src/lib-http/test-http-client.c b/src/lib-http/test-http-client.c
index 4899f1cbbb..63c337c094 100644
--- a/src/lib-http/test-http-client.c
+++ b/src/lib-http/test-http-client.c
@@ -23,7 +23,7 @@ static void payload_input(struct http_test_request *req)
 	int ret;
 
 	/* read payload */
-	while ((ret=i_stream_read_data(req->payload, &data, &size, 0)) > 0) {
+	while ((ret=i_stream_read_more(req->payload, &data, &size)) > 0) {
 		i_info("DEBUG: got data (size=%d)", (int)size); 
 		if (req->write_output)
 			write_full(1, data, size);
diff --git a/src/lib-http/test-http-transfer.c b/src/lib-http/test-http-transfer.c
index 00d0df666e..95b2e4cc46 100644
--- a/src/lib-http/test-http-transfer.c
+++ b/src/lib-http/test-http-transfer.c
@@ -278,7 +278,7 @@ static void test_http_transfer_chunked_output_valid(void)
 
 		/* send input through chunked stream; chunk size is limited */
 		for (;;) {
-			ret = i_stream_read_data(input, &rdata, &rsize, 0);
+			ret = i_stream_read_more(input, &rdata, &rsize);
 			if (ret < 0) {
 				if (input->eof)
 					ret = 1;
diff --git a/src/lib-mail/istream-attachment-extractor.c b/src/lib-mail/istream-attachment-extractor.c
index 0810181255..1b7831bba8 100644
--- a/src/lib-mail/istream-attachment-extractor.c
+++ b/src/lib-mail/istream-attachment-extractor.c
@@ -410,7 +410,7 @@ static int astream_decode_base64(struct attachment_istream *astream)
 	if (input->v_offset != part->temp_output->offset && !failed) {
 		/* write the rest of the data to the message stream */
 		extra_buf = buffer_create_dynamic(default_pool, 1024);
-		while ((ret = i_stream_read_data(input, &data, &size, 0)) > 0) {
+		while ((ret = i_stream_read_more(input, &data, &size)) > 0) {
 			buffer_append(extra_buf, data, size);
 			i_stream_skip(input, size);
 		}
@@ -510,7 +510,7 @@ astream_part_finish(struct attachment_istream *astream, const char **error_r)
 
 	/* copy data to attachment from temp file */
 	input = i_stream_create_fd(part->temp_fd, IO_BLOCK_SIZE, FALSE);
-	while (i_stream_read_data(input, &data, &size, 0) > 0) {
+	while (i_stream_read_more(input, &data, &size) > 0) {
 		o_stream_nsend(output, data, size);
 		i_stream_skip(input, size);
 	}
diff --git a/src/lib-mail/istream-qp-decoder.c b/src/lib-mail/istream-qp-decoder.c
index f41c12fb2c..4583f9b938 100644
--- a/src/lib-mail/istream-qp-decoder.c
+++ b/src/lib-mail/istream-qp-decoder.c
@@ -69,7 +69,7 @@ static ssize_t i_stream_qp_decoder_read(struct istream_private *stream)
 		}
 
 		/* need to read more input */
-		ret = i_stream_read_data(stream->parent, &data, &size, 0);
+		ret = i_stream_read_more(stream->parent, &data, &size);
 		if (ret <= 0) {
 			stream->istream.stream_errno = stream->parent->stream_errno;
 			stream->istream.eof = stream->parent->eof;
diff --git a/src/lib-mail/message-size.c b/src/lib-mail/message-size.c
index 43bbc12dad..7c430f0eb2 100644
--- a/src/lib-mail/message-size.c
+++ b/src/lib-mail/message-size.c
@@ -74,7 +74,7 @@ int message_get_body_size(struct istream *input, struct message_size *body,
 	*has_nuls_r = FALSE;
 
 	missing_cr_count = 0;
-	if ((ret = i_stream_read_data(input, &msg, &size, 0)) <= 0)
+	if ((ret = i_stream_read_more(input, &msg, &size)) <= 0)
 		return ret < 0 && input->stream_errno != 0 ? -1 : 0;
 
 	if (msg[0] == '\n')
@@ -134,7 +134,7 @@ int message_skip_virtual(struct istream *input, uoff_t virtual_skip,
 	if (virtual_skip == 0)
 		return 0;
 
-	while ((ret = i_stream_read_data(input, &msg, &size, 0)) > 0) {
+	while ((ret = i_stream_read_more(input, &msg, &size)) > 0) {
 		for (i = 0; i < size && virtual_skip > 0; i++) {
 			virtual_skip--;
 
diff --git a/src/lib-mail/test-istream-attachment.c b/src/lib-mail/test-istream-attachment.c
index 7c1fc6d173..7b6403fa0a 100644
--- a/src/lib-mail/test-istream-attachment.c
+++ b/src/lib-mail/test-istream-attachment.c
@@ -234,7 +234,7 @@ static int test_input_stream(struct istream *file_input)
 	/* get hash when directly reading input */
 	input = i_stream_create_crlf(file_input);
 	sha1_init(&hash);
-	while (i_stream_read_data(input, &data, &size, 0) > 0) {
+	while (i_stream_read_more(input, &data, &size) > 0) {
 		sha1_loop(&hash, data, size);
 		i_stream_skip(input, size);
 	}
@@ -250,7 +250,7 @@ static int test_input_stream(struct istream *file_input)
 	input2 = i_stream_create_attachment_extractor(input, &set, NULL);
 	i_stream_unref(&input);
 	base_buf = buffer_create_dynamic(default_pool, 1024);
-	while (i_stream_read_data(input2, &data, &size, 0) > 0) {
+	while (i_stream_read_more(input2, &data, &size) > 0) {
 		buffer_append(base_buf, data, size);
 		i_stream_skip(input2, size);
 	}
@@ -262,7 +262,7 @@ static int test_input_stream(struct istream *file_input)
 	i_stream_unref(&input2);
 
 	sha1_init(&hash);
-	while (i_stream_read_data(input, &data, &size, 0) > 0) {
+	while (i_stream_read_more(input, &data, &size) > 0) {
 		sha1_loop(&hash, data, size);
 		i_stream_skip(input, size);
 	}
diff --git a/src/lib-mail/test-istream-binary-converter.c b/src/lib-mail/test-istream-binary-converter.c
index 0da002f3e6..5b64b7d217 100644
--- a/src/lib-mail/test-istream-binary-converter.c
+++ b/src/lib-mail/test-istream-binary-converter.c
@@ -169,7 +169,7 @@ static int test_input_file(const char *path)
 	/* get hash when directly reading input */
 	input = i_stream_create_crlf(file_input);
 	sha1_init(&hash);
-	while (i_stream_read_data(input, &data, &size, 0) > 0) {
+	while (i_stream_read_more(input, &data, &size) > 0) {
 		sha1_loop(&hash, data, size);
 		i_stream_skip(input, size);
 	}
@@ -181,7 +181,7 @@ static int test_input_file(const char *path)
 	input = i_stream_create_crlf(file_input);
 	input2 = i_stream_create_binary_converter(input);
 	sha1_init(&hash);
-	while (i_stream_read_data(input2, &data, &size, 0) > 0) {
+	while (i_stream_read_more(input2, &data, &size) > 0) {
 		sha1_loop(&hash, data, size);
 		i_stream_skip(input2, size);
 	}
diff --git a/src/lib-mail/test-istream-qp-decoder.c b/src/lib-mail/test-istream-qp-decoder.c
index ff79d1ad57..985b9c0a38 100644
--- a/src/lib-mail/test-istream-qp-decoder.c
+++ b/src/lib-mail/test-istream-qp-decoder.c
@@ -39,7 +39,7 @@ decode_test(const char *qp_input, const char *output, bool broken_input,
 
 	for (i = 1; i <= qp_input_len; i++) {
 		test_istream_set_size(input_data, i);
-		while ((ret = i_stream_read_data(input, &data, &size, 0)) > 0) {
+		while ((ret = i_stream_read_more(input, &data, &size)) > 0) {
 			str_append_n(str, data, size);
 			i_stream_skip(input, size);
 		}
@@ -49,7 +49,7 @@ decode_test(const char *qp_input, const char *output, bool broken_input,
 	}
 	if (ret == 0) {
 		test_istream_set_allow_eof(input_data, TRUE);
-		while ((ret = i_stream_read_data(input, &data, &size, 0)) > 0) {
+		while ((ret = i_stream_read_more(input, &data, &size)) > 0) {
 			str_append_n(str, data, size);
 			i_stream_skip(input, size);
 		}
diff --git a/src/lib-ssl-iostream/iostream-openssl.c b/src/lib-ssl-iostream/iostream-openssl.c
index 54b06c0899..0f937b3cc9 100644
--- a/src/lib-ssl-iostream/iostream-openssl.c
+++ b/src/lib-ssl-iostream/iostream-openssl.c
@@ -375,7 +375,7 @@ openssl_iostream_read_more(struct ssl_iostream *ssl_io,
 		return 0;
 	}
 
-	if (i_stream_read_data(ssl_io->plain_input, data_r, size_r, 0) < 0)
+	if (i_stream_read_more(ssl_io->plain_input, data_r, size_r) < 0)
 		return -1;
 	return 0;
 }
diff --git a/src/lib-storage/index/imapc/imapc-mail.c b/src/lib-storage/index/imapc/imapc-mail.c
index 45eb058128..86068222f2 100644
--- a/src/lib-storage/index/imapc/imapc-mail.c
+++ b/src/lib-storage/index/imapc/imapc-mail.c
@@ -262,7 +262,7 @@ imapc_mail_get_headers(struct mail *_mail, const char *field,
 	if (ret < 0)
 		return -1;
 
-	while (i_stream_read_data(input, &data, &size, 0) > 0)
+	while (i_stream_read_more(input, &data, &size) > 0)
 		i_stream_skip(input, size);
 	/* the header should cached now. */
 	return index_mail_get_headers(_mail, field, decode_to_utf8, value_r);
@@ -462,7 +462,7 @@ static int imapc_mail_get_hdr_hash(struct index_mail *imail)
 		imail->data.stream->v_offset;
 	if (mail_get_hdr_stream(&imail->mail.mail, NULL, &input) < 0)
 		return -1;
-	while (i_stream_read_data(input, &data, &size, 0) > 0) {
+	while (i_stream_read_more(input, &data, &size) > 0) {
 		sha1_loop(&sha1_ctx, data, size);
 		i_stream_skip(input, size);
 	}
diff --git a/src/lib-storage/index/index-mail-binary.c b/src/lib-storage/index/index-mail-binary.c
index a9ac1feb73..e378185733 100644
--- a/src/lib-storage/index/index-mail-binary.c
+++ b/src/lib-storage/index/index-mail-binary.c
@@ -320,7 +320,7 @@ blocks_count_lines(struct binary_ctx *ctx, struct istream *full_input)
 	block_idx = 0;
 
 	/* count the number of lines each block contains */
-	while ((ret = i_stream_read_data(full_input, &data, &size, 0)) > 0) {
+	while ((ret = i_stream_read_more(full_input, &data, &size)) > 0) {
 		i_assert(cur_block_offset <= cur_block->input->v_offset);
 		if (cur_block->input->eof) {
 			/* this is the last input for this block. the input
diff --git a/src/lib-storage/index/mbox/istream-raw-mbox.c b/src/lib-storage/index/mbox/istream-raw-mbox.c
index 32f381a994..6035df32d2 100644
--- a/src/lib-storage/index/mbox/istream-raw-mbox.c
+++ b/src/lib-storage/index/mbox/istream-raw-mbox.c
@@ -624,7 +624,7 @@ int istream_raw_mbox_get_body_size(struct istream *stream,
 	}
 
 	/* have to read through the message body */
-	while (i_stream_read_data(stream, &data, &size, 0) > 0)
+	while (i_stream_read_more(stream, &data, &size) > 0)
 		i_stream_skip(stream, size);
 	i_stream_seek(stream, old_offset);
 	if (stream->stream_errno != 0)
diff --git a/src/lib-storage/mailbox-attribute.c b/src/lib-storage/mailbox-attribute.c
index 78e29131c4..be69634e48 100644
--- a/src/lib-storage/mailbox-attribute.c
+++ b/src/lib-storage/mailbox-attribute.c
@@ -230,7 +230,7 @@ int mailbox_attribute_value_to_string(struct mail_storage *storage,
 	}
 	str = t_str_new(128);
 	i_stream_seek(value->value_stream, 0);
-	while (i_stream_read_data(value->value_stream, &data, &size, 0) > 0) {
+	while (i_stream_read_more(value->value_stream, &data, &size) > 0) {
 		if (memchr(data, '\0', size) != NULL) {
 			mail_storage_set_error(storage, MAIL_ERROR_PARAMS,
 				"Attribute string value has NULs");
diff --git a/src/lib/ostream.c b/src/lib/ostream.c
index afa9777564..ac34338ded 100644
--- a/src/lib/ostream.c
+++ b/src/lib/ostream.c
@@ -381,7 +381,7 @@ off_t io_stream_copy(struct ostream *outstream, struct istream *instream)
 
 	start_offset = instream->v_offset;
 	do {
-		(void)i_stream_read_data(instream, &data, &iov.iov_len, 0);
+		(void)i_stream_read_more(instream, &data, &iov.iov_len);
 		if (iov.iov_len == 0) {
 			/* all sent */
 			if (instream->stream_errno != 0)
diff --git a/src/lib/test-istream-unix.c b/src/lib/test-istream-unix.c
index d2d9c8f031..a0890bf50d 100644
--- a/src/lib/test-istream-unix.c
+++ b/src/lib/test-istream-unix.c
@@ -33,7 +33,7 @@ test_server_read_nofd(struct istream *input, unsigned int idx)
 	const unsigned char *data;
 	size_t size;
 
-	test_assert_idx(i_stream_read_data(input, &data, &size, 0) == 1, idx);
+	test_assert_idx(i_stream_read_more(input, &data, &size) == 1, idx);
 	i_stream_skip(input, 1);
 	test_assert_idx(i_stream_unix_get_read_fd(input) == -1, idx);
 }
@@ -46,7 +46,7 @@ test_server_read_fd(struct istream *input, int wanted_fd, unsigned int idx)
 	size_t size;
 	int recv_fd;
 
-	test_assert_idx(i_stream_read_data(input, &data, &size, 0) == 1, idx);
+	test_assert_idx(i_stream_read_more(input, &data, &size) == 1, idx);
 	i_stream_skip(input, 1);
 	test_assert_idx((recv_fd = i_stream_unix_get_read_fd(input)) != -1, idx);
 	if (recv_fd != -1) {
@@ -73,7 +73,7 @@ static void test_istream_unix_server(int fd)
 	/* we still shouldn't have the fd */
 	fd_set_nonblock(fd, TRUE);
 	i_stream_unix_set_read_fd(input);
-	test_assert(i_stream_read_data(input, &data, &size, 0) == 0);
+	test_assert(i_stream_read_more(input, &data, &size) == 0);
 	test_assert(i_stream_unix_get_read_fd(input) == -1);
 	fd_set_nonblock(fd, FALSE);
 	write_one(fd);
diff --git a/src/login-common/client-common-auth.c b/src/login-common/client-common-auth.c
index 3dee6994a3..298be299e0 100644
--- a/src/login-common/client-common-auth.c
+++ b/src/login-common/client-common-auth.c
@@ -486,7 +486,7 @@ int client_auth_read_line(struct client *client)
 	size_t i, size;
 	unsigned int len;
 
-	if (i_stream_read_data(client->input, &data, &size, 0) == -1) {
+	if (i_stream_read_more(client->input, &data, &size) == -1) {
 		client_destroy(client, "Disconnected");
 		return -1;
 	}
diff --git a/src/plugins/fts-solr/solr-connection.c b/src/plugins/fts-solr/solr-connection.c
index 1ae5b16858..3449a8f938 100644
--- a/src/plugins/fts-solr/solr-connection.c
+++ b/src/plugins/fts-solr/solr-connection.c
@@ -376,7 +376,7 @@ static void solr_connection_payload_input(struct solr_connection *conn)
 	int ret;
 
 	/* read payload */
-	while ((ret = i_stream_read_data(conn->payload, &data, &size, 0)) > 0) {
+	while ((ret = i_stream_read_more(conn->payload, &data, &size)) > 0) {
 		(void)solr_xml_parse(conn, data, size, FALSE);
 		i_stream_skip(conn->payload, size);
 	}
diff --git a/src/plugins/fts/fts-parser-tika.c b/src/plugins/fts/fts-parser-tika.c
index 4a86fe20bf..075a46e11c 100644
--- a/src/plugins/fts/fts-parser-tika.c
+++ b/src/plugins/fts/fts-parser-tika.c
@@ -194,7 +194,7 @@ static void fts_parser_tika_more(struct fts_parser *_parser,
 	}
 	/* continue returning data from Tika. we'll create a new ioloop just
 	   for reading this one payload. */
-	while ((ret = i_stream_read_data(parser->payload, &data, &size, 0)) == 0) {
+	while ((ret = i_stream_read_more(parser->payload, &data, &size)) == 0) {
 		if (parser->failed)
 			break;
 		/* wait for more input from Tika */
diff --git a/src/plugins/mail-filter/ostream-ext-filter.c b/src/plugins/mail-filter/ostream-ext-filter.c
index a297d6dc8d..d4421460e6 100644
--- a/src/plugins/mail-filter/ostream-ext-filter.c
+++ b/src/plugins/mail-filter/ostream-ext-filter.c
@@ -82,7 +82,7 @@ static int o_stream_mail_filter_flush(struct ostream_private *stream)
 	if (shutdown(mstream->fd, SHUT_WR) < 0)
 		i_error("ext-filter: shutdown() failed: %m");
 
-	while ((ret = i_stream_read_data(mstream->ext_in, &data, &size, 0)) > 0) {
+	while ((ret = i_stream_read_more(mstream->ext_in, &data, &size)) > 0) {
 		ret = o_stream_send(stream->parent, data, size);
 		if (ret != (ssize_t)size) {
 			i_assert(ret < 0);
diff --git a/src/plugins/pop3-migration/pop3-migration-plugin.c b/src/plugins/pop3-migration/pop3-migration-plugin.c
index ef996abf9c..9a45814afd 100644
--- a/src/plugins/pop3-migration/pop3-migration-plugin.c
+++ b/src/plugins/pop3-migration/pop3-migration-plugin.c
@@ -197,7 +197,7 @@ int pop3_migration_get_hdr_sha1(uint32_t mail_seq, struct istream *input,
 	i_stream_unref(&input2);
 
 	sha1_init(&sha1_ctx);
-	while (i_stream_read_data(input, &data, &size, 0) > 0) {
+	while (i_stream_read_more(input, &data, &size) > 0) {
 		message_header_hash_more(&hash_method_sha1, &sha1_ctx, 2,
 					 data, size);
 		i_stream_skip(input, size);
diff --git a/src/pop3/pop3-commands.c b/src/pop3/pop3-commands.c
index adfc8fec86..2fe8a96483 100644
--- a/src/pop3/pop3-commands.c
+++ b/src/pop3/pop3-commands.c
@@ -336,7 +336,7 @@ static void fetch_callback(struct client *client)
 	int ret;
 
 	while ((ctx->body_lines > 0 || !ctx->in_body) &&
-	       i_stream_read_data(ctx->stream, &data, &size, 0) > 0) {
+	       i_stream_read_more(ctx->stream, &data, &size) > 0) {
 		if (size > 4096)
 			size = 4096;