[PATCH 3/4] fbdev: defio: Move variable state into struct fb_deferred_io_state

[Thomas Zimmermann <tzimmermann@suse.de>]

Move variable fields from struct fb_deferred_io into struct
fb_deferred_io_state. These fields are internal to the defio code
and should not be exposed to drivers. At some later point, struct
fb_defered_io might become const in all defio code.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/video/fbdev/core/fb_defio.c | 37 +++++++++++++++++------------
 include/linux/fb.h                  |  3 ---
 2 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c
index 331b1a9fe485..c6945b4422cc 100644
--- a/drivers/video/fbdev/core/fb_defio.c
+++ b/drivers/video/fbdev/core/fb_defio.c
@@ -25,6 +25,8 @@
 #include <linux/rmap.h>
 #include <linux/pagemap.h>
 
+struct address_space;
+
 /*
  * struct fb_deferred_io_state
  */
@@ -32,9 +34,13 @@
 struct fb_deferred_io_state {
 	struct kref ref;
 
+	int open_count; /* number of opened files; protected by fb_info lock */
+	struct address_space *mapping; /* page cache object for fb device */
+
 	struct mutex lock; /* mutex that protects the pageref list */
 	/* fields protected by lock */
 	struct fb_info *info;
+	struct list_head pagereflist; /* list of pagerefs for touched pages */
 };
 
 static struct fb_deferred_io_state *fb_deferred_io_state_alloc(void)
@@ -48,11 +54,14 @@ static struct fb_deferred_io_state *fb_deferred_io_state_alloc(void)
 	kref_init(&fbdefio_state->ref);
 	mutex_init(&fbdefio_state->lock);
 
+	INIT_LIST_HEAD(&fbdefio_state->pagereflist);
+
 	return fbdefio_state;
 }
 
 static void fb_deferred_io_state_release(struct fb_deferred_io_state *fbdefio_state)
 {
+	WARN_ON(!list_empty(&fbdefio_state->pagereflist));
 	mutex_destroy(&fbdefio_state->lock);
 
 	kfree(fbdefio_state);
@@ -147,7 +156,8 @@ static struct fb_deferred_io_pageref *fb_deferred_io_pageref_get(struct fb_info
 								 struct page *page)
 {
 	struct fb_deferred_io *fbdefio = info->fbdefio;
-	struct list_head *pos = &fbdefio->pagereflist;
+	struct fb_deferred_io_state *fbdefio_state = info->fbdefio_state;
+	struct list_head *pos = &fbdefio_state->pagereflist;
 	struct fb_deferred_io_pageref *pageref, *cur;
 
 	pageref = fb_deferred_io_pageref_lookup(info, offset, page);
@@ -171,7 +181,7 @@ static struct fb_deferred_io_pageref *fb_deferred_io_pageref_get(struct fb_info
 		 * pages. If possible, drivers should try to work with
 		 * unsorted page lists instead.
 		 */
-		list_for_each_entry(cur, &fbdefio->pagereflist, list) {
+		list_for_each_entry(cur, &fbdefio_state->pagereflist, list) {
 			if (cur->offset > pageref->offset)
 				break;
 		}
@@ -222,7 +232,7 @@ static vm_fault_t fb_deferred_io_fault(struct vm_fault *vmf)
 	if (!vmf->vma->vm_file)
 		fb_err(info, "no mapping available\n");
 
-	BUG_ON(!info->fbdefio->mapping);
+	fb_WARN_ON_ONCE(info, !fbdefio_state->mapping);
 
 	mutex_unlock(&fbdefio_state->lock);
 
@@ -364,20 +374,20 @@ static void fb_deferred_io_work(struct work_struct *work)
 	/* here we wrprotect the page's mappings, then do all deferred IO. */
 	mutex_lock(&fbdefio_state->lock);
 #ifdef CONFIG_MMU
-	list_for_each_entry(pageref, &fbdefio->pagereflist, list) {
+	list_for_each_entry(pageref, &fbdefio_state->pagereflist, list) {
 		struct page *page = pageref->page;
 		pgoff_t pgoff = pageref->offset >> PAGE_SHIFT;
 
-		mapping_wrprotect_range(fbdefio->mapping, pgoff,
+		mapping_wrprotect_range(fbdefio_state->mapping, pgoff,
 					page_to_pfn(page), 1);
 	}
 #endif
 
 	/* driver's callback with pagereflist */
-	fbdefio->deferred_io(info, &fbdefio->pagereflist);
+	fbdefio->deferred_io(info, &fbdefio_state->pagereflist);
 
 	/* clear the list */
-	list_for_each_entry_safe(pageref, next, &fbdefio->pagereflist, list)
+	list_for_each_entry_safe(pageref, next, &fbdefio_state->pagereflist, list)
 		fb_deferred_io_pageref_put(pageref, info);
 
 	mutex_unlock(&fbdefio_state->lock);
@@ -402,7 +412,6 @@ int fb_deferred_io_init(struct fb_info *info)
 	fbdefio_state->info = info;
 
 	INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
-	INIT_LIST_HEAD(&fbdefio->pagereflist);
 	if (fbdefio->delay == 0) /* set a default of 1 s */
 		fbdefio->delay = HZ;
 
@@ -431,11 +440,11 @@ void fb_deferred_io_open(struct fb_info *info,
 			 struct inode *inode,
 			 struct file *file)
 {
-	struct fb_deferred_io *fbdefio = info->fbdefio;
+	struct fb_deferred_io_state *fbdefio_state = info->fbdefio_state;
 
-	fbdefio->mapping = file->f_mapping;
+	fbdefio_state->mapping = file->f_mapping;
 	file->f_mapping->a_ops = &fb_deferred_io_aops;
-	fbdefio->open_count++;
+	fbdefio_state->open_count++;
 }
 EXPORT_SYMBOL_GPL(fb_deferred_io_open);
 
@@ -446,16 +455,15 @@ static void fb_deferred_io_lastclose(struct fb_info *info)
 
 void fb_deferred_io_release(struct fb_info *info)
 {
-	struct fb_deferred_io *fbdefio = info->fbdefio;
+	struct fb_deferred_io_state *fbdefio_state = info->fbdefio_state;
 
-	if (!--fbdefio->open_count)
+	if (!--fbdefio_state->open_count)
 		fb_deferred_io_lastclose(info);
 }
 EXPORT_SYMBOL_GPL(fb_deferred_io_release);
 
 void fb_deferred_io_cleanup(struct fb_info *info)
 {
-	struct fb_deferred_io *fbdefio = info->fbdefio;
 	struct fb_deferred_io_state *fbdefio_state = info->fbdefio_state;
 
 	fb_deferred_io_lastclose(info);
@@ -469,6 +477,5 @@ void fb_deferred_io_cleanup(struct fb_info *info)
 	fb_deferred_io_state_put(fbdefio_state);
 
 	kvfree(info->pagerefs);
-	fbdefio->mapping = NULL;
 }
 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
diff --git a/include/linux/fb.h b/include/linux/fb.h
index 0bf3f1a5cf1e..2a9d05e51ff4 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -216,9 +216,6 @@ struct fb_deferred_io {
 	/* delay between mkwrite and deferred handler */
 	unsigned long delay;
 	bool sort_pagereflist; /* sort pagelist by offset */
-	int open_count; /* number of opened files; protected by fb_info lock */
-	struct list_head pagereflist; /* list of pagerefs for touched pages */
-	struct address_space *mapping; /* page cache object for fb device */
 	/* callback */
 	struct page *(*get_page)(struct fb_info *info, unsigned long offset);
 	void (*deferred_io)(struct fb_info *info, struct list_head *pagelist);
-- 
2.52.0