Kevin Wolf <[email protected]> writes:
> Currently, if the user requests aio=native, but forgets to choose a
> cache mode that sets O_DIRECT, that request is silently ignored and raw
> falls back to aio=threads.
>
> Deprecate that behaviour so we can make it an error in future qemu
> versions.
>
> Signed-off-by: Kevin Wolf <[email protected]>
> ---
> block/raw-posix.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index f0b4488..929b6ae 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -503,6 +503,14 @@ static int raw_open_common(BlockDriverState *bs, QDict
> *options,
> error_setg_errno(errp, -ret, "Could not set AIO state");
> goto fail;
> }
> + if (!s->use_aio && (bdrv_flags & BDRV_O_NATIVE_AIO)) {
> + fprintf(stderr, "WARNING: aio=native was specified for '%s', but "
> + "it requires cache.direct=on, which was not "
> + "specified. Falling back to aio=threads.\n"
> + " This will become an error condition in "
> + "future QEMU versions.\n",
> + bs->filename);
> + }
> #endif
>
> s->has_discard = true;
error_report(), please, because:
* No warning in a monitor that isn't on the tty:
$ socat UNIX:test-hmp STDIO
QEMU 2.2.50 monitor - type 'help' for more information
(qemu) drive_add "" if=none,aio=native,file=tmp.qcow2
drive_add "" if=none,aio=native,file=tmp.qcow2
OK
* The warning gives no clue on location. Not nice when the culprit is
actually deep in some -readconfig file.
A quick grep counts 42 instances of "warning:', 53 '"Warning:', and 20
'"WARNING:'. We suck at consistency :)
For a COW image, I get the warning twice, and once for image, and once
for the backing image:
$ qemu-system-x86_64 -nodefaults -drive if=none,aio=native,file=tmp.qcow2
WARNING: aio=native was specified for 'tmp.qcow2', but it requires
cache.direct=on, which was not specified. Falling back to aio=threads.
This will become an error condition in future QEMU versions.
WARNING: aio=native was specified for 'tmp.img', but it requires
cache.direct=on, which was not specified. Falling back to aio=threads.
This will become an error condition in future QEMU versions.
Not sure whether this can or should be avoided.
With error_report() instead of fprintf():
Reviewed-by: Markus Armbruster <[email protected]>
