Re: [Patch v2 02/15] CIFS: Add support for direct pages in rdata

[Tom Talpey]

On 6/25/2018 5:01 PM, Jason Gunthorpe wrote:
> On Sat, Jun 23, 2018 at 09:50:20PM -0400, Tom Talpey wrote:
> > On 5/30/2018 3:47 PM, Long Li wrote:
> > > From: Long Li <longli@xxxxxxxxxxxxx>
> > >
> > > Add a function to allocate rdata without allocating pages for data
> > > transfer. This gives the caller an option to pass a number of pages
> > > that point to the data buffer.
> > >
> > > rdata is still reponsible for free those pages after it's done.
> >
> > "Caller" is still responsible? Or is the rdata somehow freeing itself
> > via another mechanism?
> >
> > > Signed-off-by: Long Li <longli@xxxxxxxxxxxxx>
> > >   fs/cifs/cifsglob.h |  2 +-
> > >   fs/cifs/file.c     | 23 ++++++++++++++++++++---
> > >   2 files changed, 21 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
> > > index 8d16c3e..56864a87 100644
> > > +++ b/fs/cifs/cifsglob.h
> > > @@ -1179,7 +1179,7 @@ struct cifs_readdata {
> > >   	unsigned int			tailsz;
> > >   	unsigned int			credits;
> > >   	unsigned int			nr_pages;
> > > -	struct page			*pages[];
> > > +	struct page			**pages;
> >
> > Technically speaking, these are syntactically equivalent. It may not
> > be worth changing this historic definition.
>
> [] is a C99 'flex array', it has a different allocation behavior than
> ** and is not interchangeable..

In that case, it's an even better reason to not change the declaration.

Tom.