Re: [Qemu-block] [PATCH v2 1/1] block: improve error handling in raw_open

[John Snow]

On 07/26/2016 07:34 AM, Halil Pasic wrote:
> Make raw_open for POSIX more consistent in handling errors by setting
> the error object also when qemu_open fails. The error object was set
> generally set in case of errors, but I guess this case was overlooked.
> Do the same for win32.
> 
> Signed-off-by: Halil Pasic <address@hidden>
> Reviewed-by: Sascha Silbe <address@hidden>
> Tested-by: Marc Hartmayer <address@hidden> (POSIX only)
> 

In the future, please configure your patch sending utility to send V2
patches as a new top-level thread, and not as a reply-to your V1.
Patches are easier to miss for maintainers when they show up as replies
to previously-nacked patchsets.

Thanks, and sorry for the pedanticism.
--js

> ---
> 
> Stumbled upon this (POSIX) while testing VMs with too many SCSI disks in
> respect to my nofile limit. When open hits the nofile limit while trying
> to hotplug yet another SCSI disk via libvirt we end up with no adequate
> error message (one stating too many files). Sadly this patch in not
> sufficient to fix this problem because drive_new (/qemu/blockdev.c)
> handles errors using error_report_err which is documented as not to be
> used in QMP context. Do not have a patch for that, because I'm unsure
> whats the best way to deal with it. My guess right now is to make sure
> we propagate errors at least until reaching code which is called  only
> QMP in context and handle communicating the error to the requester of
> the operation there. Any suggestions or ideas?
> 
> The win32 part was not tested, and the sole reason I touched it is
> to not introduce unnecessary divergence.
> 
> v1 -> v2:
> * fixed win32 by the correct error_setg_*
> * use the original errno consequently
> 
> ---
>  block/raw-posix.c | 1 +
>  block/raw-win32.c | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/block/raw-posix.c b/block/raw-posix.c
> index c979ac3..786f068 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -485,6 +485,7 @@ static int raw_open_common(BlockDriverState *bs, QDict 
> *options,
>      s->fd = -1;
>      fd = qemu_open(filename, s->open_flags, 0644);
>      if (fd < 0) {
> +        error_setg_errno(errp, errno, "Could not open file");
>          ret = -errno;
>          if (ret == -EROFS) {
>              ret = -EACCES;
> diff --git a/block/raw-win32.c b/block/raw-win32.c
> index 62edb1a..6f074f4 100644
> --- a/block/raw-win32.c
> +++ b/block/raw-win32.c
> @@ -337,6 +337,7 @@ static int raw_open(BlockDriverState *bs, QDict *options, 
> int flags,
>      if (s->hfile == INVALID_HANDLE_VALUE) {
>          int err = GetLastError();
>  
> +        error_setg_win32(errp, err, "Could not open file");
>          if (err == ERROR_ACCESS_DENIED) {
>              ret = -EACCES;
>          } else {
>