block/blkio.c | 108 ++++++++++++++++++++++++++------------------------ 1 file changed, 56 insertions(+), 52 deletions(-)
When QEMU is built with --enable-modules, the module_block.py script
parses block/*.c to find block drivers that are built as modules. The
script generates a table of block drivers called block_driver_modules[].
This table is used for block driver module loading.
The blkio.c driver uses macros to define its BlockDriver structs. This
was done to avoid code duplication but the module_block.py script is
unable to parse the macro. The result is that libblkio-based block
drivers can be built as modules but will not be found at runtime.
One fix is to make the module_block.py script or build system fancier so
it can parse C macros (e.g. by parsing the preprocessed source code). I
chose not to do this because it raises the complexity of the build,
making future issues harder to debug.
Keep things simple: use the macro to avoid duplicating BlockDriver
function pointers but define .format_name and .protocol_name manually
for each BlockDriver. This way the module_block.py is able to parse the
code.
Also get rid of the block driver name macros (e.g. DRIVER_IO_URING)
because module_block.py cannot parse them either.
Fixes: fd66dbd424f5 ("blkio: add libblkio block driver")
Reported-by: Qing Wang <qinwang@redhat.com>
Cc: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
v2:
- Drop unnecessary backslashes [Stefano]
---
block/blkio.c | 108 ++++++++++++++++++++++++++------------------------
1 file changed, 56 insertions(+), 52 deletions(-)
diff --git a/block/blkio.c b/block/blkio.c
index 527323d625..1798648134 100644
--- a/block/blkio.c
+++ b/block/blkio.c
@@ -22,16 +22,6 @@
#include "block/block-io.h"
-/*
- * Keep the QEMU BlockDriver names identical to the libblkio driver names.
- * Using macros instead of typing out the string literals avoids typos.
- */
-#define DRIVER_IO_URING "io_uring"
-#define DRIVER_NVME_IO_URING "nvme-io_uring"
-#define DRIVER_VIRTIO_BLK_VFIO_PCI "virtio-blk-vfio-pci"
-#define DRIVER_VIRTIO_BLK_VHOST_USER "virtio-blk-vhost-user"
-#define DRIVER_VIRTIO_BLK_VHOST_VDPA "virtio-blk-vhost-vdpa"
-
/*
* Allocated bounce buffers are kept in a list sorted by buffer address.
*/
@@ -744,15 +734,15 @@ static int blkio_file_open(BlockDriverState *bs, QDict *options, int flags,
return ret;
}
- if (strcmp(blkio_driver, DRIVER_IO_URING) == 0) {
+ if (strcmp(blkio_driver, "io_uring") == 0) {
ret = blkio_io_uring_open(bs, options, flags, errp);
- } else if (strcmp(blkio_driver, DRIVER_NVME_IO_URING) == 0) {
+ } else if (strcmp(blkio_driver, "nvme-io_uring") == 0) {
ret = blkio_nvme_io_uring(bs, options, flags, errp);
- } else if (strcmp(blkio_driver, DRIVER_VIRTIO_BLK_VFIO_PCI) == 0) {
+ } else if (strcmp(blkio_driver, "virtio-blk-vfio-pci") == 0) {
ret = blkio_virtio_blk_common_open(bs, options, flags, errp);
- } else if (strcmp(blkio_driver, DRIVER_VIRTIO_BLK_VHOST_USER) == 0) {
+ } else if (strcmp(blkio_driver, "virtio-blk-vhost-user") == 0) {
ret = blkio_virtio_blk_common_open(bs, options, flags, errp);
- } else if (strcmp(blkio_driver, DRIVER_VIRTIO_BLK_VHOST_VDPA) == 0) {
+ } else if (strcmp(blkio_driver, "virtio-blk-vhost-vdpa") == 0) {
ret = blkio_virtio_blk_common_open(bs, options, flags, errp);
} else {
g_assert_not_reached();
@@ -1028,49 +1018,63 @@ static void blkio_refresh_limits(BlockDriverState *bs, Error **errp)
* - truncate
*/
-#define BLKIO_DRIVER(name, ...) \
- { \
- .format_name = name, \
- .protocol_name = name, \
- .instance_size = sizeof(BDRVBlkioState), \
- .bdrv_file_open = blkio_file_open, \
- .bdrv_close = blkio_close, \
- .bdrv_co_getlength = blkio_co_getlength, \
- .bdrv_co_truncate = blkio_truncate, \
- .bdrv_co_get_info = blkio_co_get_info, \
- .bdrv_attach_aio_context = blkio_attach_aio_context, \
- .bdrv_detach_aio_context = blkio_detach_aio_context, \
- .bdrv_co_pdiscard = blkio_co_pdiscard, \
- .bdrv_co_preadv = blkio_co_preadv, \
- .bdrv_co_pwritev = blkio_co_pwritev, \
- .bdrv_co_flush_to_disk = blkio_co_flush, \
- .bdrv_co_pwrite_zeroes = blkio_co_pwrite_zeroes, \
- .bdrv_refresh_limits = blkio_refresh_limits, \
- .bdrv_register_buf = blkio_register_buf, \
- .bdrv_unregister_buf = blkio_unregister_buf, \
- __VA_ARGS__ \
- }
+/*
+ * Do not include .format_name and .protocol_name because module_block.py
+ * does not parse macros in the source code.
+ */
+#define BLKIO_DRIVER_COMMON \
+ .instance_size = sizeof(BDRVBlkioState), \
+ .bdrv_file_open = blkio_file_open, \
+ .bdrv_close = blkio_close, \
+ .bdrv_co_getlength = blkio_co_getlength, \
+ .bdrv_co_truncate = blkio_truncate, \
+ .bdrv_co_get_info = blkio_co_get_info, \
+ .bdrv_attach_aio_context = blkio_attach_aio_context, \
+ .bdrv_detach_aio_context = blkio_detach_aio_context, \
+ .bdrv_co_pdiscard = blkio_co_pdiscard, \
+ .bdrv_co_preadv = blkio_co_preadv, \
+ .bdrv_co_pwritev = blkio_co_pwritev, \
+ .bdrv_co_flush_to_disk = blkio_co_flush, \
+ .bdrv_co_pwrite_zeroes = blkio_co_pwrite_zeroes, \
+ .bdrv_refresh_limits = blkio_refresh_limits, \
+ .bdrv_register_buf = blkio_register_buf, \
+ .bdrv_unregister_buf = blkio_unregister_buf,
-static BlockDriver bdrv_io_uring = BLKIO_DRIVER(
- DRIVER_IO_URING,
+/*
+ * Use the same .format_name and .protocol_name as the libblkio driver name for
+ * consistency.
+ */
+
+static BlockDriver bdrv_io_uring = {
+ .format_name = "io_uring",
+ .protocol_name = "io_uring",
.bdrv_needs_filename = true,
-);
+ BLKIO_DRIVER_COMMON
+};
-static BlockDriver bdrv_nvme_io_uring = BLKIO_DRIVER(
- DRIVER_NVME_IO_URING,
-);
+static BlockDriver bdrv_nvme_io_uring = {
+ .format_name = "nvme-io_uring",
+ .protocol_name = "nvme-io_uring",
+ BLKIO_DRIVER_COMMON
+};
-static BlockDriver bdrv_virtio_blk_vfio_pci = BLKIO_DRIVER(
- DRIVER_VIRTIO_BLK_VFIO_PCI
-);
+static BlockDriver bdrv_virtio_blk_vfio_pci = {
+ .format_name = "virtio-blk-vfio-pci",
+ .protocol_name = "virtio-blk-vfio-pci",
+ BLKIO_DRIVER_COMMON
+};
-static BlockDriver bdrv_virtio_blk_vhost_user = BLKIO_DRIVER(
- DRIVER_VIRTIO_BLK_VHOST_USER
-);
+static BlockDriver bdrv_virtio_blk_vhost_user = {
+ .format_name = "virtio-blk-vhost-user",
+ .protocol_name = "virtio-blk-vhost-user",
+ BLKIO_DRIVER_COMMON
+};
-static BlockDriver bdrv_virtio_blk_vhost_vdpa = BLKIO_DRIVER(
- DRIVER_VIRTIO_BLK_VHOST_VDPA
-);
+static BlockDriver bdrv_virtio_blk_vhost_vdpa = {
+ .format_name = "virtio-blk-vhost-vdpa",
+ .protocol_name = "virtio-blk-vhost-vdpa",
+ BLKIO_DRIVER_COMMON
+};
static void bdrv_blkio_init(void)
{
--
2.40.1On Tue, Jul 04, 2023 at 02:34:36PM +0200, Stefan Hajnoczi wrote:
>When QEMU is built with --enable-modules, the module_block.py script
>parses block/*.c to find block drivers that are built as modules. The
>script generates a table of block drivers called block_driver_modules[].
>This table is used for block driver module loading.
>
>The blkio.c driver uses macros to define its BlockDriver structs. This
>was done to avoid code duplication but the module_block.py script is
>unable to parse the macro. The result is that libblkio-based block
>drivers can be built as modules but will not be found at runtime.
>
>One fix is to make the module_block.py script or build system fancier so
>it can parse C macros (e.g. by parsing the preprocessed source code). I
>chose not to do this because it raises the complexity of the build,
>making future issues harder to debug.
>
>Keep things simple: use the macro to avoid duplicating BlockDriver
>function pointers but define .format_name and .protocol_name manually
>for each BlockDriver. This way the module_block.py is able to parse the
>code.
>
>Also get rid of the block driver name macros (e.g. DRIVER_IO_URING)
>because module_block.py cannot parse them either.
>
>Fixes: fd66dbd424f5 ("blkio: add libblkio block driver")
>Reported-by: Qing Wang <qinwang@redhat.com>
>Cc: Stefano Garzarella <sgarzare@redhat.com>
>Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
>---
>v2:
>- Drop unnecessary backslashes [Stefano]
>---
> block/blkio.c | 108 ++++++++++++++++++++++++++------------------------
> 1 file changed, 56 insertions(+), 52 deletions(-)
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
© 2016 - 2024 Red Hat, Inc.