The raw_get_aio_fd() function allows virtio-blk-data-plane to get the
file descriptor of a raw image file with Linux AIO enabled. This
interface is really a layering violation that can be resolved once the
block layer is able to run outside the global mutex - at that point
virtio-blk-data-plane will switch from custom Linux AIO code to using
the block layer.
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
---
block.h | 9 +++++++++
block/raw-posix.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 43 insertions(+)
diff --git a/block.h b/block.h
index 722c620..2dc6aaf 100644
--- a/block.h
+++ b/block.h
@@ -365,6 +365,15 @@ void bdrv_disable_copy_on_read(BlockDriverState *bs);
void bdrv_set_in_use(BlockDriverState *bs, int in_use);
int bdrv_in_use(BlockDriverState *bs);
+#ifdef CONFIG_LINUX_AIO
+int raw_get_aio_fd(BlockDriverState *bs);
+#else
+static inline int raw_get_aio_fd(BlockDriverState *bs)
+{
+ return -ENOTSUP;
+}
+#endif
+
enum BlockAcctType {
BDRV_ACCT_READ,
BDRV_ACCT_WRITE,
diff --git a/block/raw-posix.c b/block/raw-posix.c
index f2f0404..fc04981 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -1768,6 +1768,40 @@ static BlockDriver bdrv_host_cdrom = {
};
#endif /* __FreeBSD__ */
+#ifdef CONFIG_LINUX_AIO
+/**
+ * Return the file descriptor for Linux AIO
+ *
+ * This function is a layering violation and should be removed when it becomes
+ * possible to call the block layer outside the global mutex. It allows the
+ * caller to hijack the file descriptor so I/O can be performed outside the
+ * block layer.
+ */
+int raw_get_aio_fd(BlockDriverState *bs)
+{
+ BDRVRawState *s;
+
+ if (!bs->drv) {
+ return -ENOMEDIUM;
+ }
+
+ if (bs->drv == bdrv_find_format("raw")) {
+ bs = bs->file;
+ }
+
+ /* raw-posix has several protocols so just check for raw_aio_readv */
+ if (bs->drv->bdrv_aio_readv != raw_aio_readv) {
+ return -ENOTSUP;
+ }
+
+ s = bs->opaque;
+ if (!s->use_aio) {
+ return -ENOTSUP;
+ }
+ return s->fd;
+}
+#endif /* CONFIG_LINUX_AIO */
+
static void bdrv_file_init(void)
{
/*
--
1.8.0
