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

[Souptick Joarder]

On Mon, May 21, 2018 at 11:39 PM, Souptick Joarder <jrdr.linux at 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 at 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.