It seems that with the recent usage of ->page_mkwrite() a little detail

was overlooked.
.22-rc1 merged OCFS2 usage of this hook

.23-rc1 merged XFS usage

.24-rc1 will most likely merge NFS usage
Please consider this for .23 final and maybe even .22.x
---

Subject: mm: set_page_dirty_balance() vs ->page_mkwrite()
All the current page_mkwrite() implementations also set the page dirty. Which

results in the set_page_dirty_balance() call to _not_ call balance, because the

page is already found dirty.
This allows us to dirty a _lot_ of pages without ever hitting

balance_dirty_pages().  Not good (tm).
Force a balance call if ->page_mkwrite() was successful.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

---

 include/linux/writeback.h |    2 +-

 mm/memory.c               |    9 +++++++--

 mm/page-writeback.c       |    4 ++--

 3 files changed, 10 insertions(+), 5 deletions(-)
Index: linux-2.6/include/linux/writeback.h

===================================================================

--- linux-2.6.orig/include/linux/writeback.h

+++ linux-2.6/include/linux/writeback.h

@@ -137,7 +137,7 @@ int sync_page_range(struct inode *inode,

 			loff_t pos, loff_t count);

 int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,

 			   loff_t pos, loff_t count);

-void set_page_dirty_balance(struct page *page);

+void set_page_dirty_balance(struct page *page, int page_mkwrite);

 void writeback_set_ratelimit(void);
 /* pdflush.c */

Index: linux-2.6/mm/memory.c

===================================================================

--- linux-2.6.orig/mm/memory.c

+++ linux-2.6/mm/memory.c

@@ -1559,6 +1559,7 @@ static int do_wp_page(struct mm_struct *

 	struct page *old_page, *new_page;

 	pte_t entry;

 	int reuse = 0, ret = 0;

+	int page_mkwrite = 0;

 	struct page *dirty_page = NULL;
 	old_page = vm_normal_page(vma, address, orig_pte);

@@ -1607,6 +1608,8 @@ static int do_wp_page(struct mm_struct *

 			page_cache_release(old_page);

 			i...
[ message continues ]

-

block_page_mkwrite() is just using generic interfaces to do this,

same as pretty much any write() system call. The idea was to make it

as similar to the write() call path as possible...
However, unlike generic_file_buffered_write(), we are not calling

balance_dirty_pages_ratelimited(mapping) between

->prepare/commit_write call pairs.  Perhaps this should be added to

block_page_mkwrite() after the page is unlocked....
Cheers,
Dave.

--

Dave Chinner

Principal Engineer

SGI Australian Software Group

-

That sounds pretty sane, in terms of matching with

generic_file_buffered_write.

-

I agree. We could also insert a call to balance_dirty_pages_ratelimited() in

__ocfs2_page_mkwrite.

	--Mark
--

Mark Fasheh

Senior Software Developer, Oracle

mark.fasheh@oracle.com

-

Hmm, Peter's patch got merged -- I suppose that's fine for 2.6.23 though...
-