Revert "fb_defio: Remove custom address_space_operations"

Commit ccf953d8f3d6 makes framebuffers which use deferred I/O stop
displaying updates after the first one.  This is because the pages
handled by fb_defio no longer have a page_mapping().  That prevents
page_mkclean() from marking the PTEs as clean, and so writes are only
noticed the first time.

Reported-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/YLZEhv0cpZp8uVE3@casper.infradead.org

diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c
index b292887..a591d29 100644 (file)
--- a/drivers/video/fbdev/core/fb_defio.c
+++ b/drivers/video/fbdev/core/fb_defio.c
@@ -52,6 +52,13 @@ 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;
@@ -144,6 +151,17 @@ 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;
@@ -194,12 +212,29 @@ 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;
+       struct page *page;
+       int i;
 
        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);
 }
 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);

diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 072780b..98f1930 100644 (file)
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -1415,6 +1415,10 @@ __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 a8dccd2..ecfbcc0 100644 (file)
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -659,6 +659,9 @@ 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);