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

[Halil Pasic <pasic@linux.vnet.ibm.com>]

On 07/27/2016 05:28 PM, 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 <pasic@linux.vnet.ibm.com>
> Reviewed-by: Sascha Silbe <silbe@linux.vnet.ibm.com>
> Tested-by: Marc Hartmayer <mhartmay@linux.vnet.ibm.com> (POSIX only)
> 
> ---
> 
> 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.
> 
> v2 -> v3:
> * first save errno then error_setg_errno
> 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 6ed7547..51e4ddb 100644
> --- a/block/raw-posix.c
> +++ b/block/raw-posix.c
> @@ -436,6 +436,7 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
>      fd = qemu_open(filename, s->open_flags, 0644);
>      if (fd < 0) {
>          ret = -errno;
> +        error_setg_errno(errp, errno, "Could not open file");
>          if (ret == -EROFS) {
>              ret = -EACCES;
>          }
> diff --git a/block/raw-win32.c b/block/raw-win32.c
> index 56f45fe..185dd9b 100644
> --- a/block/raw-win32.c
> +++ b/block/raw-win32.c
> @@ -338,6 +338,7 @@ 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 {
> 

Sorry its v3.