Re: [Qemu-devel] [PATCH v4 14/15] block: Remove assertions from update_flags_from_options()

[Max Reitz <mreitz@redhat.com>]

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On 07.11.18 13:59, Alberto Garcia wrote:
> This function takes three options (cache.direct, cache.no-flush and
> read-only) from a QemuOpts object and updates the flags accordingly.

and auto-read-only now

> 
> If any of those options is not set (because it was missing from the
> original QDict or because it had an invalid value) then the function
> aborts with a failed assertion:
> 
>    $ qemu-io -c 'reopen -o read-only=foo' hd.qcow2
>    block.c:1126: update_flags_from_options: Assertion `qemu_opt_find(opts, BDRV_OPT_CACHE_DIRECT)' failed.
>    Aborted
> 
> This assertion is unnecessary, and it forces any caller of
> bdrv_reopen() to pass all the aforementioned three options. This may

*four

> have made sense in order to remove ambiguity when bdrv_reopen() was
> taking both flags and options, but that's not the case anymore.
> 
> It's also unnecessary if we want to validate the option values,
> because bdrv_reopen_prepare() already takes care of that, as we can
> see if we remove the assertions:
> 
>    $ qemu-io -c 'reopen -o read-only=foo' hd.qcow2
>    Parameter 'read-only' expects 'on' or 'off'
> 
> Signed-off-by: Alberto Garcia <berto@igalia.com>
> ---
>  block.c                    | 4 ----
>  tests/qemu-iotests/133     | 8 ++++++++
>  tests/qemu-iotests/133.out | 6 ++++++
>  3 files changed, 14 insertions(+), 4 deletions(-)

Hm, seems like one way to solve it and I can't really find issue with
it.  So, let's first give a

Reviewed-by: Max Reitz <mreitz@redhat.com>

However, I wonder why you dropped your patch from v1 for this.  It
seemed more reasonable to me.  You're basically trading half-updating
the flags for just not touching them at all (and the latter seems
better, even though it's all an error in the end anyway).

> diff --git a/block.c b/block.c
> index 8bc808d6f3..68f1e3b45e 100644
> --- a/block.c
> +++ b/block.c
> @@ -1139,24 +1139,20 @@ static void update_flags_from_options(int *flags, QemuOpts *opts)
>  {
>      *flags &= ~BDRV_O_CACHE_MASK;
>  
> -    assert(qemu_opt_find(opts, BDRV_OPT_CACHE_NO_FLUSH));
>      if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_NO_FLUSH, false)) {
>          *flags |= BDRV_O_NO_FLUSH;
>      }
>  
> -    assert(qemu_opt_find(opts, BDRV_OPT_CACHE_DIRECT));
>      if (qemu_opt_get_bool_del(opts, BDRV_OPT_CACHE_DIRECT, false)) {
>          *flags |= BDRV_O_NOCACHE;
>      }
>  
>      *flags &= ~BDRV_O_RDWR;

Unrelated to this patch, but isn't BDRV_O_AUTO_RDONLY missing here?

Max

>  
> -    assert(qemu_opt_find(opts, BDRV_OPT_READ_ONLY));
>      if (!qemu_opt_get_bool_del(opts, BDRV_OPT_READ_ONLY, false)) {
>          *flags |= BDRV_O_RDWR;
>      }
>  
> -    assert(qemu_opt_find(opts, BDRV_OPT_AUTO_READ_ONLY));
>      if (qemu_opt_get_bool_del(opts, BDRV_OPT_AUTO_READ_ONLY, false)) {
>          *flags |= BDRV_O_AUTO_RDONLY;
>      }
> diff --git a/tests/qemu-iotests/133 b/tests/qemu-iotests/133
> index 14e6b3b972..59d5e2ea25 100755
> --- a/tests/qemu-iotests/133
> +++ b/tests/qemu-iotests/133
> @@ -101,6 +101,14 @@ $QEMU_IO -c 'reopen -w -o read-only=on' $TEST_IMG
>  $QEMU_IO -c 'reopen -c none -o cache.direct=on' $TEST_IMG
>  $QEMU_IO -c 'reopen -c writeback -o cache.direct=on' $TEST_IMG
>  $QEMU_IO -c 'reopen -c directsync -o cache.no-flush=on' $TEST_IMG
> +
> +echo
> +echo "=== Check that invalid options are handled correctly ==="
> +echo
> +
> +$QEMU_IO -c 'reopen -o read-only=foo' $TEST_IMG
> +$QEMU_IO -c 'reopen -o cache.no-flush=bar' $TEST_IMG
> +$QEMU_IO -c 'reopen -o cache.direct=baz' $TEST_IMG
>  # success, all done
>  echo "*** done"
>  rm -f $seq.full
> diff --git a/tests/qemu-iotests/133.out b/tests/qemu-iotests/133.out
> index 48a9d087f0..551096a9c4 100644
> --- a/tests/qemu-iotests/133.out
> +++ b/tests/qemu-iotests/133.out
> @@ -32,4 +32,10 @@ Cannot set both -r/-w and 'read-only'
>  Cannot set both -c and the cache options
>  Cannot set both -c and the cache options
>  Cannot set both -c and the cache options
> +
> +=== Check that invalid options are handled correctly ===
> +
> +Parameter 'read-only' expects 'on' or 'off'
> +Parameter 'cache.no-flush' expects 'on' or 'off'
> +Parameter 'cache.direct' expects 'on' or 'off'
>  *** done
> 



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