Re: [Qemu-devel] [PATCH v8 6/9] file-posix: support BDRV_REQ_ALLOCATE

[Anton Nefedov <anton.nefedov@virtuozzo.com>]

On 12/3/2018 1:16 PM, Anton Nefedov wrote:
> Current write_zeroes implementation is good enough to satisfy this flag too
> 
> Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com>
> Reviewed-by: Alberto Garcia <berto@igalia.com>
> Reviewed-by: Max Reitz <mreitz@redhat.com>

strictly speaking this patch differs from v8 as well
(rebase required an extra change, see below)
so perhaps I should have stripped the review tags too

> ---
>   block/file-posix.c | 10 +++++++++-
>   1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/block/file-posix.c b/block/file-posix.c
> index 7f2cc63..2136df9 100644
> --- a/block/file-posix.c
> +++ b/block/file-posix.c
> @@ -560,7 +560,10 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
>       }
>       if (S_ISREG(st.st_mode)) {
>           s->discard_zeroes = true;
> +#ifdef CONFIG_FALLOCATE
>           s->has_fallocate = true;
> +        bs->supported_zero_flags |= BDRV_REQ_ALLOCATE;
> +#endif
>       }
>       if (S_ISBLK(st.st_mode)) {
>   #ifdef BLKDISCARDZEROES
> @@ -595,10 +598,11 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
>   #ifdef CONFIG_XFS
>       if (platform_test_xfs_fd(s->fd)) {
>           s->is_xfs = true;
> +        bs->supported_zero_flags |= BDRV_REQ_ALLOCATE;
>       }
>   #endif
>   
> -    bs->supported_zero_flags = s->discard_zeroes ? BDRV_REQ_MAY_UNMAP : 0;
> +    bs->supported_zero_flags |= s->discard_zeroes ? BDRV_REQ_MAY_UNMAP : 0;
>       ret = 0;

(this change is new in v9)

>   fail:
>       if (filename && (bdrv_flags & BDRV_O_TEMPORARY)) {
> @@ -1416,6 +1420,10 @@ static ssize_t handle_aiocb_write_zeroes(RawPosixAIOData *aiocb)
>           }
>           s->has_fallocate = false;
>       }
> +
> +    if (!s->has_fallocate) {
> +        aiocb->bs->supported_zero_flags &= ~BDRV_REQ_ALLOCATE;
> +    }
>   #endif
>   
>       return -ENOTSUP;
>