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raw-posix: add raw_get_aio_fd() for virtio-blk-data-plane

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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 <stefanha@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2012-11-14 11:43:23 +01:00
parent 5928023cef
commit 4065742ac0
2 changed files with 43 additions and 0 deletions
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34
block/raw-posix.c
View File

@ -1776,6 +1776,40 @@ 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)
{
/*

9
include/block/block.h
View File

@ -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,