At Fri, 8 Aug 2014 13:31:39 +0800,
Liu Yuan wrote:
>
> On Thu, Aug 07, 2014 at 04:28:40PM +0900, Hitoshi Mitake wrote:
> > Recently, sheepdog revived its VDI locking functionality. This patch
> > updates sheepdog driver of QEMU for this feature:
> >
> > 1. Improve error message when QEMU fails to acquire lock of
> > VDI. Current sheepdog driver prints an error message "VDI isn't
> > locked" when it fails to acquire lock. It is a little bit confusing
> > because the mesage says VDI isn't locked but it is actually locked by
> > other VM. This patch modifies this confusing message.
> >
> > 2. Change error code for a case of failed locking. -EBUSY is a
> > suitable one.
> >
> > Reported-by: Valerio Pachera <[email protected]>
> > Cc: Kevin Wolf <[email protected]>
> > Cc: Stefan Hajnoczi <[email protected]>
> > Cc: Liu Yuan <[email protected]>
> > Cc: MORITA Kazutaka <[email protected]>
> > Signed-off-by: Hitoshi Mitake <[email protected]>
> > ---
> > block/sheepdog.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/block/sheepdog.c b/block/sheepdog.c
> > index 36f76f0..0b3f86d 100644
> > --- a/block/sheepdog.c
> > +++ b/block/sheepdog.c
> > @@ -1112,9 +1112,13 @@ static int find_vdi_name(BDRVSheepdogState *s, const
> > char *filename,
> >
> > if (rsp->result != SD_RES_SUCCESS) {
> > error_setg(errp, "cannot get vdi info, %s, %s %" PRIu32 " %s",
> > + rsp->result == SD_RES_VDI_NOT_LOCKED ?
>
> I'm puzzled by this check.
>
> we use SD_RES_VDI_LOCKED to indicate vid is already locked, no?
We use SD_RES_VDI_NOT_LOCKED for indicating locking by this VM fails.
>
> > + "VDI is already locked by other VM" :
> > sd_strerror(rsp->result), filename, snapid, tag);
> > if (rsp->result == SD_RES_NO_VDI) {
> > ret = -ENOENT;
> > + } else if (rsp->result == SD_RES_VDI_NOT_LOCKED) {
> > + ret = -EBUSY;
> > } else {
> > ret = -EIO;
> > }
>
> It is better to use switch case to handle the result.
using switch statement in this case only increases a number of lines
of code:
Current change:
if (rsp->result == SD_RES_NO_VDI) {
ret = -ENOENT;
} else if (rsp->result == SD_RES_VDI_NOT_LOCKED) {
...
Change with switch:
switch (rsp->result) {
case SD_RES_NO_VDI:
ret = -ENOENT;
break;
case SD_RES_VDI_NOT_LOCKED:
...
The change with switch statement requires one more line for break;. I
think if statement is suitable for this case.
Thanks,
Hitoshi
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