Commit 3ed38112 authored by Thomas Zimmermann's avatar Thomas Zimmermann
Browse files

fbdev: Refactor implementation of page_mkwrite 



Refactor the page-write handler for deferred I/O. Drivers use the
function to let fbdev track written pages of mmap'ed framebuffer
memory.

v3:
	* keep locking within track-pages function for readability (Sam)
v2:
	* don't export the helper until we have an external caller

Signed-off-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: default avatarJavier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220429100834.18898-4-tzimmermann@suse.de
parent 56c134f7

drivers/video/fbdev/core/fb_defio.c

+38 −15
Original line number Diff line number Diff line
@@ -143,26 +143,17 @@ int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasy 
}

EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);



/* vm_ops->page_mkwrite handler */

static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf)

/*

 * Adds a page to the dirty list. Call this from struct

 * vm_operations_struct.page_mkwrite.

 */

static vm_fault_t fb_deferred_io_track_page(struct fb_info *info, unsigned long offset,

					    struct page *page)

{

	struct page *page = vmf->page;

	struct fb_info *info = vmf->vma->vm_private_data;

	struct fb_deferred_io *fbdefio = info->fbdefio;

	struct fb_deferred_io_pageref *pageref;

	unsigned long offset;

	vm_fault_t ret;



	offset = (vmf->address - vmf->vma->vm_start);



	/* this is a callback we get when userspace first tries to

	write to the page. we schedule a workqueue. that workqueue

	will eventually mkclean the touched pages and execute the

	deferred framebuffer IO. then if userspace touches a page

	again, we repeat the same scheme */



	file_update_time(vmf->vma->vm_file);



	/* protect against the workqueue changing the page list */

	mutex_lock(&fbdefio->lock);
@@ -197,6 +188,38 @@ static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf) 
	return ret;

}



/*

 * fb_deferred_io_page_mkwrite - Mark a page as written for deferred I/O

 * @fb_info: The fbdev info structure

 * @vmf: The VM fault

 *

 * This is a callback we get when userspace first tries to

 * write to the page. We schedule a workqueue. That workqueue

 * will eventually mkclean the touched pages and execute the

 * deferred framebuffer IO. Then if userspace touches a page

 * again, we repeat the same scheme.

 *

 * Returns:

 * VM_FAULT_LOCKED on success, or a VM_FAULT error otherwise.

 */

static vm_fault_t fb_deferred_io_page_mkwrite(struct fb_info *info, struct vm_fault *vmf)

{

	unsigned long offset = vmf->address - vmf->vma->vm_start;

	struct page *page = vmf->page;



	file_update_time(vmf->vma->vm_file);



	return fb_deferred_io_track_page(info, offset, page);

}



/* vm_ops->page_mkwrite handler */

static vm_fault_t fb_deferred_io_mkwrite(struct vm_fault *vmf)

{

	struct fb_info *info = vmf->vma->vm_private_data;



	return fb_deferred_io_page_mkwrite(info, vmf);

}



static const struct vm_operations_struct fb_deferred_io_vm_ops = {

	.fault		= fb_deferred_io_fault,

	.page_mkwrite	= fb_deferred_io_mkwrite,