Re: [PATCH v3 4/4] block: switch to use qemu_open/qemu_create for improved errors

[Philippe Mathieu-Daudé]

On 7/24/20 3:25 PM, Daniel P. Berrangé wrote:
> Currently at startup if using cache=none on a filesystem lacking
> O_DIRECT such as tmpfs, at startup QEMU prints
> 
> qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: file system may not 
> support O_DIRECT
> qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: Could not open 
> '/tmp/foo.img': Invalid argument
> 
> while at QMP level the hint is missing, so QEMU reports just
> 
>   "error": {
>       "class": "GenericError",
>       "desc": "Could not open '/tmp/foo.img': Invalid argument"
>   }
> 
> which is close to useless for the end user trying to figure out what
> they did wrong.
> 
> With this change at startup QEMU prints
> 
> qemu-system-x86_64: -drive file=/tmp/foo.img,cache=none: Unable to open 
> '/tmp/foo.img' flags 0x4000: filesystem does not support O_DIRECT
> 
> while at the QMP level QEMU reports a massively more informative
> 
>   "error": {
>      "class": "GenericError",
>      "desc": "Unable to open '/tmp/foo.img' flags 0x4002: filesystem does not 
> support O_DIRECT"
>   }
> 
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> ---
>  block/file-posix.c            | 18 +++++++-----------
>  block/file-win32.c            |  6 ++----
>  tests/qemu-iotests/051.out    |  4 ++--
>  tests/qemu-iotests/051.pc.out |  4 ++--
>  tests/qemu-iotests/061.out    |  2 +-
>  tests/qemu-iotests/069.out    |  2 +-
>  tests/qemu-iotests/082.out    |  4 ++--
>  tests/qemu-iotests/111.out    |  2 +-
>  tests/qemu-iotests/226.out    |  6 +++---
>  tests/qemu-iotests/232.out    | 12 ++++++------
>  tests/qemu-iotests/244.out    |  6 +++---
>  11 files changed, 30 insertions(+), 36 deletions(-)
> 
> diff --git a/block/file-posix.c b/block/file-posix.c
> index bac2566f10..c63926d592 100644
> --- a/block/file-posix.c
> +++ b/block/file-posix.c
> @@ -630,11 +630,10 @@ static int raw_open_common(BlockDriverState *bs, QDict 
> *options,
>      raw_parse_flags(bdrv_flags, &s->open_flags, false);
>  
>      s->fd = -1;
> -    fd = qemu_open_old(filename, s->open_flags, 0644);
> +    fd = qemu_open(filename, s->open_flags, errp);
>      ret = fd < 0 ? -errno : 0;
>  
>      if (ret < 0) {
> -        error_setg_file_open(errp, -ret, filename);
>          if (ret == -EROFS) {
>              ret = -EACCES;
>          }
> @@ -1032,15 +1031,13 @@ static int raw_reconfigure_getfd(BlockDriverState 
> *bs, int flags,
>          }
>      }
>  
> -    /* If we cannot use fcntl, or fcntl failed, fall back to qemu_open_old() 
> */
> +    /* If we cannot use fcntl, or fcntl failed, fall back to qemu_open() */
>      if (fd == -1) {
>          const char *normalized_filename = bs->filename;
>          ret = raw_normalize_devicepath(&normalized_filename, errp);
>          if (ret >= 0) {
> -            assert(!(*open_flags & O_CREAT));
> -            fd = qemu_open_old(normalized_filename, *open_flags);
> +            fd = qemu_open(normalized_filename, *open_flags, errp);
>              if (fd == -1) {
> -                error_setg_errno(errp, errno, "Could not reopen file");
>                  return -1;
>              }
>          }
> @@ -2411,10 +2408,9 @@ raw_co_create(BlockdevCreateOptions *options, Error 
> **errp)
>      }
>  
>      /* Create file */
> -    fd = qemu_open_old(file_opts->filename, O_RDWR | O_CREAT | O_BINARY, 
> 0644);
> +    fd = qemu_create(file_opts->filename, O_RDWR | O_BINARY, 0644, errp);
>      if (fd < 0) {
>          result = -errno;
> -        error_setg_errno(errp, -result, "Could not create file");
>          goto out;
>      }
[...]

Nice :)

I haven't checked the iotest errors; assuming a CI will take care of it:
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>