Re: [PATCH 1/1] cr: ext4: use filemap_checkpoint for ext4 file backed mmaps

[Oren Laadan <orenl-RdfvBDnrOixBDgjK7y7TUQ@public.gmane.org>]

queued for ckpt-v18.

Serge E. Hallyn wrote:
> I don't know if this is "the right thing" to do, or if
> there will be special ext4 cases which this doesn't handle,
> but all of my cr_tests pass with this patch applied on F11
> with an ext4 rootfs (and fail without on trying to checkpoint
> a library on ext4fs bc it has its own vm_ops but no
> vm_ops->checkpoint()).
> 
> Signed-off-by: Serge Hallyn <serue-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> ---
>  fs/ext4/file.c     |    3 +++
>  include/linux/mm.h |    1 +
>  mm/filemap.c       |    2 +-
>  3 files changed, 5 insertions(+), 1 deletions(-)
> 
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index a99bcc3..cdac137 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -133,6 +133,9 @@ force_commit:
>  static struct vm_operations_struct ext4_file_vm_ops = {
>  	.fault		= filemap_fault,
>  	.page_mkwrite   = ext4_page_mkwrite,
> +#ifdef CONFIG_CHECKPOINT
> +	.checkpoint	= filemap_checkpoint,
> +#endif
>  };
>  
>  static int ext4_file_mmap(struct file *file, struct vm_area_struct *vma)
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 5f341ac..5b9b217 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1185,6 +1185,7 @@ extern void truncate_inode_pages_range(struct address_space *,
>  
>  /* generic vm_area_ops exported for stackable file systems */
>  extern int filemap_fault(struct vm_area_struct *, struct vm_fault *);
> +extern int filemap_checkpoint(struct ckpt_ctx *ctx, struct vm_area_struct *vma);
>  
>  /* mm/page-writeback.c */
>  int write_one_page(struct page *page, int wait);
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 0c4906f..eb7653d 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1650,7 +1650,7 @@ page_not_uptodate:
>  EXPORT_SYMBOL(filemap_fault);
>  
>  #ifdef CONFIG_CHECKPOINT
> -static int filemap_checkpoint(struct ckpt_ctx *ctx, struct vm_area_struct *vma)
> +int filemap_checkpoint(struct ckpt_ctx *ctx, struct vm_area_struct *vma)
>  {
>  	struct file *file = vma->vm_file;
>  	int vma_objref;