On Mon, 3 Jul 2023 at 12:55, Stefano Garzarella <sgarz...@redhat.com> wrote:
>
> On Mon, Jul 03, 2023 at 12:35:24PM +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 <qinw...@redhat.com>
> >Cc: Stefano Garzarella <sgarz...@redhat.com>
> >Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
> >---
> > block/blkio.c | 110 ++++++++++++++++++++++++++------------------------
> > 1 file changed, 57 insertions(+), 53 deletions(-)
> >
> >diff --git a/block/blkio.c b/block/blkio.c
> >index 527323d625..589f829a83 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,
> >- .bdrv_needs_filename = true,
> >-);
> >+/*
> >+ * Use the same .format_name and .protocol_name as the libblkio driver name
> >for
> >+ * consistency.
> >+ */
> >
> >-static BlockDriver bdrv_nvme_io_uring = BLKIO_DRIVER(
> >- DRIVER_NVME_IO_URING,
> >-);
> >+static BlockDriver bdrv_io_uring = {
> >+ .format_name = "io_uring", \
>
> Thanks for the fast fix :-)
>
> Minor thing: we can remove the backslash here and in the following
> `struct BlockDriver`s fields.
>
> With or without this:
>
> Reviewed-by: Stefano Garzarella <sgarz...@redhat.com>
Oops, the slash is not necessary.
Thanks!
Stefan
