Re: [Qemu-devel] [PATCH for-2.10 07/16] block/file-posix: Generalize raw_regular_truncate

[Stefan Hajnoczi]

On Mon, Mar 20, 2017 at 04:11:24PM +0100, Max Reitz wrote:
> On 20.03.2017 12:00, Stefan Hajnoczi wrote:
> > On Mon, Mar 13, 2017 at 10:40:36PM +0100, Max Reitz wrote:
> >> +static int raw_regular_truncate(int fd, BlockDriverState *bs, int64_t 
> >> offset,
> > 
> > The presence of both a file descriptor and a BlockDriverState (actually
> > it must be a BDRVRawState) arguments is unusual.  It seems bs is needed
> > for bdrv_getlength().
> > 
> > How about using fstat(fd, &st) and then dropping bs and create?
> 
> Well, I could do that, but bdrv_getlength() is a bit simpler and I don't
> see much of an issue with specifying both an fd and a bs.

Arguments that provide overlapping information make the function harder
to understand and use correctly (there are combinations of these
arguments that are invalid or don't make sense).  Saving a few lines of
code in the function implementation is a poor trade-off IMO.

Stefan

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