Re: [Qemu-devel] [PATCH v3 04/19] block: move aio initialization into a helper function

[Kevin Wolf <kwolf@redhat.com>]

Am 18.09.2012 20:53, schrieb Jeff Cody:
> Move AIO initialization for raw-posix block driver into a helper function.
> 
> In addition to just code motion, the aio_ctx pointer is checked for NULL,
> prior to calling laio_init(), to make sure laio_init() is only run once.
> 
> Signed-off-by: Jeff Cody <jcody@redhat.com>
> ---
>  block/raw-posix.c | 55 +++++++++++++++++++++++++++++++++++--------------------
>  1 file changed, 35 insertions(+), 20 deletions(-)
> 
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index 6be20b1..ee55f79 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -185,6 +185,40 @@ static int raw_normalize_devicepath(const char **filename)
>  }
>  #endif
>  
> +static int raw_set_aio(void **aio_ctx, int *use_aio, int bdrv_flags)
> +{
> +#ifdef CONFIG_LINUX_AIO
> +    int ret = -1;
> +    assert(aio_ctx != NULL);
> +    assert(use_aio != NULL);
> +    /*
> +     * Currently Linux do AIO only for files opened with O_DIRECT
> +     * specified so check NOCACHE flag too
> +     */
> +    if ((bdrv_flags & (BDRV_O_NOCACHE|BDRV_O_NATIVE_AIO)) ==
> +                      (BDRV_O_NOCACHE|BDRV_O_NATIVE_AIO)) {
> +
> +        /* if non-NULL, laio_init() has already been run */
> +        if (*aio_ctx == NULL) {
> +            *aio_ctx = laio_init();
> +            if (!*aio_ctx) {
> +                goto error;
> +            }
> +        }
> +        *use_aio = 1;
> +    } else {
> +        *use_aio = 0;
> +    }
> +
> +    ret = 0;
> +
> +error:
> +    return ret;
> +#else
> +    return 0;
> +#endif
> +}
> +
>  static int raw_open_common(BlockDriverState *bs, const char *filename,
>                             int bdrv_flags, int open_flags)
>  {
> @@ -239,26 +273,7 @@ static int raw_open_common(BlockDriverState *bs, const char *filename,
>          goto out_free_buf;
>      }
>  
> -#ifdef CONFIG_LINUX_AIO
> -    /*
> -     * Currently Linux do AIO only for files opened with O_DIRECT
> -     * specified so check NOCACHE flag too
> -     */
> -    if ((bdrv_flags & (BDRV_O_NOCACHE|BDRV_O_NATIVE_AIO)) ==
> -                      (BDRV_O_NOCACHE|BDRV_O_NATIVE_AIO)) {
> -
> -        s->aio_ctx = laio_init();
> -        if (!s->aio_ctx) {
> -            goto out_free_buf;
> -        }
> -        s->use_aio = 1;
> -    } else
> -#endif
> -    {
> -#ifdef CONFIG_LINUX_AIO
> -        s->use_aio = 0;
> -#endif
> -    }
> +    raw_set_aio(&s->aio_ctx, &s->use_aio, bdrv_flags);

This should check the return value to handle laio_init() failure properly.

Kevin