[patch 08/16] fbdefio: add set_page_dirty handler to deferred IO FB

[Greg KH]

2.6.25-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Ian Campbell <ijc@xxxxxxxxxxxxxx>

commit d847471d063663b9f36927d265c66a270c0cfaab upstream

Fixes kernel BUG at lib/radix-tree.c:473.

Previously the handler was incidentally provided by tmpfs but this was
removed with:

  commit 14fcc23fdc78e9d32372553ccf21758a9bd56fa1
  Author: Hugh Dickins <hugh@xxxxxxxxxxx>
  Date:   Mon Jul 28 15:46:19 2008 -0700

    tmpfs: fix kernel BUG in shmem_delete_inode

relying on this behaviour was incorrect in any case and the BUG also
appeared when the device node was on an ext3 filesystem.

v2: override a_ops at open() time rather than mmap() time to minimise
races per AKPM's concerns.

Signed-off-by: Ian Campbell <ijc@xxxxxxxxxxxxxx>
Cc: Jaya Kumar <jayakumar.lkml@xxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Hugh Dickins <hugh@xxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxxx>
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Cc: Kel Modderman <kel@xxxxxxxxxx>
Cc: Markus Armbruster <armbru@xxxxxxxxxx>
Cc: Krzysztof Helt <krzysztof.h1@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/video/fb_defio.c |   19 +++++++++++++++++++
 drivers/video/fbmem.c    |    4 ++++
 include/linux/fb.h       |    3 +++
 3 files changed, 26 insertions(+)

--- a/drivers/video/fb_defio.c
+++ b/drivers/video/fb_defio.c
@@ -114,6 +114,17 @@ static struct vm_operations_struct fb_de
 	.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,
+};
+
 static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
 {
 	vma->vm_ops = &fb_deferred_io_vm_ops;
@@ -163,6 +174,14 @@ void fb_deferred_io_init(struct fb_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)
 {
 	void *screen_base = (void __force *) info->screen_base;
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1315,6 +1315,10 @@ fb_open(struct inode *inode, struct file
 		if (res)
 			module_put(info->fbops->owner);
 	}
+#ifdef CONFIG_FB_DEFERRED_IO
+	if (info->fbdefio)
+		fb_deferred_io_open(info, inode, file);
+#endif
 	return res;
 }
 
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -966,6 +966,9 @@ static inline void __fb_pad_aligned_buff
 
 /* drivers/video/fb_defio.c */
 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, struct dentry *dentry,
 				int datasync);

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