fb_defio: Remove custom address_space_operations

There's no need to give the page an address_space.  Leaving the
page->mapping as NULL will cause the VM to handle set_page_dirty()
the same way that it's set now, and that was the only reason to
set the address_space in the first place.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 drivers/video/fbdev/core/fb_defio.c | 33 -----------------------------
 drivers/video/fbdev/core/fbmem.c    |  4 ----
 include/linux/fb.h                  |  3 ---
 3 files changed, 40 deletions(-)

Looks good, just one super minor nit inline.

Reviewed-by: William Kucharski <william.kucharski@oracle.com>

> On Mar 10, 2021, at 6:51 AM, Matthew Wilcox (Oracle) <willy@infradead.org> wrote:
> 
> There's no need to give the page an address_space.  Leaving the
> page->mapping as NULL will cause the VM to handle set_page_dirty()
> the same way that it's set now, and that was the only reason to
> set the address_space in the first place.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
> drivers/video/fbdev/core/fb_defio.c | 33 -----------------------------
> drivers/video/fbdev/core/fbmem.c    |  4 ----
> include/linux/fb.h                  |  3 ---
> 3 files changed, 40 deletions(-)
> 
> diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c
> index a591d291b231..1bb208b3c4bb 100644
> --- a/drivers/video/fbdev/core/fb_defio.c
> +++ b/drivers/video/fbdev/core/fb_defio.c
> @@ -52,13 +52,6 @@ static vm_fault_t fb_deferred_io_fault(struct vm_fault *vmf)
> 		return VM_FAULT_SIGBUS;
> 
> 	get_page(page);
> -
> -	if (vmf->vma->vm_file)
> -		page->mapping = vmf->vma->vm_file->f_mapping;
> -	else
> -		printk(KERN_ERR "no mapping available\n");
> -
> -	BUG_ON(!page->mapping);
> 	page->index = vmf->pgoff;
> 
> 	vmf->page = page;
> @@ -151,17 +144,6 @@ static const struct vm_operations_struct fb_deferred_io_vm_ops = {
> 	.page_mkwrite	= fb_deferred_io_mkwrite,
> };
> 
> -static int fb_deferred_io_set_page_dirty(struct page *page)
> -{
> -	if (!PageDirty(page))
> -		SetPageDirty(page);
> -	return 0;
> -}
> -
> -static const struct address_space_operations fb_deferred_io_aops = {
> -	.set_page_dirty = fb_deferred_io_set_page_dirty,
> -};
> -
> int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
> {
> 	vma->vm_ops = &fb_deferred_io_vm_ops;
> @@ -212,14 +194,6 @@ void fb_deferred_io_init(struct fb_info *info)
> }
> EXPORT_SYMBOL_GPL(fb_deferred_io_init);
> 
> -void fb_deferred_io_open(struct fb_info *info,
> -			 struct inode *inode,
> -			 struct file *file)
> -{
> -	file->f_mapping->a_ops = &fb_deferred_io_aops;
> -}
> -EXPORT_SYMBOL_GPL(fb_deferred_io_open);
> -
> void fb_deferred_io_cleanup(struct fb_info *info)
> {
> 	struct fb_deferred_io *fbdefio = info->fbdefio;
> @@ -228,13 +202,6 @@ void fb_deferred_io_cleanup(struct fb_info *info)
> 
> 	BUG_ON(!fbdefio);
> 	cancel_delayed_work_sync(&info->deferred_work);
> -
> -	/* clear out the mapping that we setup */
> -	for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
> -		page = fb_deferred_io_page(info, i);
> -		page->mapping = NULL;
> -	}
> -
> 	mutex_destroy(&fbdefio->lock);
> }

We no longer need the definition of "int i" right before the BUG_ON().

> EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
> diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
> index 06f5805de2de..372b52a2befa 100644
> --- a/drivers/video/fbdev/core/fbmem.c
> +++ b/drivers/video/fbdev/core/fbmem.c
> @@ -1415,10 +1415,6 @@ __releases(&info->lock)
> 		if (res)
> 			module_put(info->fbops->owner);
> 	}
> -#ifdef CONFIG_FB_DEFERRED_IO
> -	if (info->fbdefio)
> -		fb_deferred_io_open(info, inode, file);
> -#endif
> out:
> 	unlock_fb_info(info);
> 	if (res)
> diff --git a/include/linux/fb.h b/include/linux/fb.h
> index ecfbcc0553a5..a8dccd23c249 100644
> --- a/include/linux/fb.h
> +++ b/include/linux/fb.h
> @@ -659,9 +659,6 @@ static inline void __fb_pad_aligned_buffer(u8 *dst, u32 d_pitch,
> /* drivers/video/fb_defio.c */
> int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma);
> extern void fb_deferred_io_init(struct fb_info *info);
> -extern void fb_deferred_io_open(struct fb_info *info,
> -				struct inode *inode,
> -				struct file *file);
> extern void fb_deferred_io_cleanup(struct fb_info *info);
> extern int fb_deferred_io_fsync(struct file *file, loff_t start,
> 				loff_t end, int datasync);
> -- 
> 2.30.0
> 
>