[lustre-devel] [PATCH v3] staging: lustre: Change return type to vm_fault_t

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Jun 12, 2018 at 02:00:47AM +0530, Souptick Joarder wrote:
> On Mon, May 21, 2018 at 11:39 PM, Souptick Joarder <jrdr.linux@gmail.com> wrote:
> > Use new return type vm_fault_t for fault handler. For
> > now, this is just documenting that the function returns
> > a VM_FAULT value rather than an errno. Once all instances
> > are converted, vm_fault_t will become a distinct type.
> >
> > Ref-> commit 1c8f422059ae ("mm: change return type to
> > vm_fault_t") was added in 4.17-rc1 to introduce the new
> > typedef vm_fault_t. Currently we are making change to all
> > drivers to return vm_fault_t for page fault handlers. As
> > part of that lustre driver is also getting changed to
> > return vm_fault_t type.
> >
> > Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
> > ---
> > v2: updated the change log
> >
> > v3: updated the change log
> >
> >  drivers/staging/lustre/lustre/llite/llite_mmap.c | 35 ++++++++++++------------
> >  1 file changed, 18 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/staging/lustre/lustre/llite/llite_mmap.c b/drivers/staging/lustre/lustre/llite/llite_mmap.c
> > index c0533bd..5b8fd10 100644
> > --- a/drivers/staging/lustre/lustre/llite/llite_mmap.c
> > +++ b/drivers/staging/lustre/lustre/llite/llite_mmap.c
> > @@ -231,7 +231,7 @@ static int ll_page_mkwrite0(struct vm_area_struct *vma, struct page *vmpage,
> >         return result;
> >  }
> >
> > -static inline int to_fault_error(int result)
> > +static inline vm_fault_t to_fault_error(int result)
> >  {
> >         switch (result) {
> >         case 0:
> > @@ -261,7 +261,7 @@ static inline int to_fault_error(int result)
> >   * \retval VM_FAULT_ERROR on general error
> >   * \retval NOPAGE_OOM not have memory for allocate new page
> >   */
> > -static int ll_fault0(struct vm_area_struct *vma, struct vm_fault *vmf)
> > +static vm_fault_t ll_fault0(struct vm_area_struct *vma, struct vm_fault *vmf)
> >  {
> >         struct lu_env      *env;
> >         struct cl_io        *io;
> > @@ -269,16 +269,16 @@ static int ll_fault0(struct vm_area_struct *vma, struct vm_fault *vmf)
> >         struct page          *vmpage;
> >         unsigned long       ra_flags;
> >         int                   result = 0;
> > -       int                   fault_ret = 0;
> > +       vm_fault_t              fault_ret = 0;
> >         u16 refcheck;
> >
> >         env = cl_env_get(&refcheck);
> >         if (IS_ERR(env))
> > -               return PTR_ERR(env);
> > +               return VM_FAULT_ERROR;
> >
> >         io = ll_fault_io_init(env, vma, vmf->pgoff, &ra_flags);
> >         if (IS_ERR(io)) {
> > -               result = to_fault_error(PTR_ERR(io));
> > +               fault_ret = to_fault_error(PTR_ERR(io));
> >                 goto out;
> >         }
> >
> > @@ -319,15 +319,15 @@ static int ll_fault0(struct vm_area_struct *vma, struct vm_fault *vmf)
> >         if (result != 0 && !(fault_ret & VM_FAULT_RETRY))
> >                 fault_ret |= to_fault_error(result);
> >
> > -       CDEBUG(D_MMAP, "%s fault %d/%d\n", current->comm, fault_ret, result);
> > +       CDEBUG(D_MMAP, "%s fault %x/%d\n", current->comm, fault_ret, result);
> >         return fault_ret;
> >  }
> >
> > -static int ll_fault(struct vm_fault *vmf)
> > +static vm_fault_t ll_fault(struct vm_fault *vmf)
> >  {
> >         int count = 0;
> >         bool printed = false;
> > -       int result;
> > +       vm_fault_t result;
> >         sigset_t set;
> >
> >         /* Only SIGKILL and SIGTERM are allowed for fault/nopage/mkwrite
> > @@ -364,18 +364,19 @@ static int ll_fault(struct vm_fault *vmf)
> >         return result;
> >  }
> >
> > -static int ll_page_mkwrite(struct vm_fault *vmf)
> > +static vm_fault_t ll_page_mkwrite(struct vm_fault *vmf)
> >  {
> >         struct vm_area_struct *vma = vmf->vma;
> >         int count = 0;
> >         bool printed = false;
> >         bool retry;
> > -       int result;
> > +       int err;
> > +       vm_fault_t ret;
> >
> >         file_update_time(vma->vm_file);
> >         do {
> >                 retry = false;
> > -               result = ll_page_mkwrite0(vma, vmf->page, &retry);
> > +               err = ll_page_mkwrite0(vma, vmf->page, &retry);
> >
> >                 if (!printed && ++count > 16) {
> >                         const struct dentry *de = vma->vm_file->f_path.dentry;
> > @@ -387,25 +388,25 @@ static int ll_page_mkwrite(struct vm_fault *vmf)
> >                 }
> >         } while (retry);
> >
> > -       switch (result) {
> > +       switch (err) {
> >         case 0:
> >                 LASSERT(PageLocked(vmf->page));
> > -               result = VM_FAULT_LOCKED;
> > +               ret = VM_FAULT_LOCKED;
> >                 break;
> >         case -ENODATA:
> >         case -EAGAIN:
> >         case -EFAULT:
> > -               result = VM_FAULT_NOPAGE;
> > +               ret = VM_FAULT_NOPAGE;
> >                 break;
> >         case -ENOMEM:
> > -               result = VM_FAULT_OOM;
> > +               ret = VM_FAULT_OOM;
> >                 break;
> >         default:
> > -               result = VM_FAULT_SIGBUS;
> > +               ret = VM_FAULT_SIGBUS;
> >                 break;
> >         }
> >
> > -       return result;
> > +       return ret;
> >  }
> >
> >  /**
> > --
> > 1.9.1
> >
> 
> If no further comment, we would like to get this patch in 4.18-rc-X.

Why?  Is it a regression fix?  That's all that is allowed after -rc1.

And have you tried applying it to Linus's current tree?  :)

thanks,

greg k-h