fbdefio: add set_page_dirty handler to deferred IO FB

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@veritas.com>
  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@hellion.org.uk>
Cc: Jaya Kumar <jayakumar.lkml@gmail.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Johannes Weiner <hannes@saeurebad.de>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Kel Modderman <kel@otaku42.de>
Cc: Markus Armbruster <armbru@redhat.com>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/video/fb_defio.c b/drivers/video/fb_defio.c
index 59df132cc3756deda96bfcce5d453a309e803a15..4835bdc4e9f1819615ab2454549f9a637d01a0e1 100644 (file)
--- a/drivers/video/fb_defio.c
+++ b/drivers/video/fb_defio.c
@@ -114,6 +114,17 @@ static 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,
+};
+
 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 *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;

diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index 776f7fcd2fbf4f508a0bb72398391aeb8f5a32d0..ce6b5da41c7cf1fc1bb65571d9e4425cf6aecc24 100644 (file)
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1340,6 +1340,10 @@ fb_open(struct inode *inode, struct file *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;
 }
 

diff --git a/include/linux/fb.h b/include/linux/fb.h
index 72295b099228637fe7a6291eca43790b91260334..dd82c76ea9c34359558c5f866861fbd13ea2a59b 100644 (file)
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -973,6 +973,9 @@ static inline void __fb_pad_aligned_buffer(u8 *dst, u32 d_pitch,
 
 /* 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);