Re: [PATCH] fix task dirty balancing

[yamamoto@valinux.co.jp (YAMAMOTO Takashi)]

hi,

> Please beat me to cleaning up this stuff - otherwise I'll have to look
> at it when I get back from holidays.

how about the following?

YAMAMOTO Takashi


Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
---

diff --git a/fs/buffer.c b/fs/buffer.c
index 4ffb5bb..1bc833d 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -699,41 +699,6 @@ void mark_buffer_dirty_inode(struct buffer_head *bh, struct inode *inode)
 EXPORT_SYMBOL(mark_buffer_dirty_inode);
 
 /*
- * Mark the page dirty, and set it dirty in the radix tree, and mark the inode
- * dirty.
- *
- * If warn is true, then emit a warning if the page is not uptodate and has
- * not been truncated.
- */
-static int __set_page_dirty(struct page *page,
-		struct address_space *mapping, int warn)
-{
-	if (unlikely(!mapping))
-		return !TestSetPageDirty(page);
-
-	if (TestSetPageDirty(page))
-		return 0;
-
-	spin_lock_irq(&mapping->tree_lock);
-	if (page->mapping) {	/* Race with truncate? */
-		WARN_ON_ONCE(warn && !PageUptodate(page));
-
-		if (mapping_cap_account_dirty(mapping)) {
-			__inc_zone_page_state(page, NR_FILE_DIRTY);
-			__inc_bdi_stat(mapping->backing_dev_info,
-					BDI_RECLAIMABLE);
-			task_io_account_write(PAGE_CACHE_SIZE);
-		}
-		radix_tree_tag_set(&mapping->page_tree,
-				page_index(page), PAGECACHE_TAG_DIRTY);
-	}
-	spin_unlock_irq(&mapping->tree_lock);
-	__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
-
-	return 1;
-}
-
-/*
  * Add a page to the dirty page list.
  *
  * It is a sad fact of life that this function is called from several places
@@ -762,22 +727,21 @@ int __set_page_dirty_buffers(struct page *page)
 {
 	struct address_space *mapping = page_mapping(page);
 
-	if (unlikely(!mapping))
-		return !TestSetPageDirty(page);
-
-	spin_lock(&mapping->private_lock);
-	if (page_has_buffers(page)) {
-		struct buffer_head *head = page_buffers(page);
-		struct buffer_head *bh = head;
+	if (likely(mapping)) {
+		spin_lock(&mapping->private_lock);
+		if (page_has_buffers(page)) {
+			struct buffer_head *head = page_buffers(page);
+			struct buffer_head *bh = head;
 
-		do {
-			set_buffer_dirty(bh);
-			bh = bh->b_this_page;
-		} while (bh != head);
+			do {
+				set_buffer_dirty(bh);
+				bh = bh->b_this_page;
+			} while (bh != head);
+		}
+		spin_unlock(&mapping->private_lock);
 	}
-	spin_unlock(&mapping->private_lock);
 
-	return __set_page_dirty(page, mapping, 1);
+	return __set_page_dirty_nobuffers(page);
 }
 EXPORT_SYMBOL(__set_page_dirty_buffers);
 
@@ -1220,7 +1184,7 @@ void mark_buffer_dirty(struct buffer_head *bh)
 	}
 
 	if (!test_set_buffer_dirty(bh))
-		__set_page_dirty(bh->b_page, page_mapping(bh->b_page), 0);
+		__set_page_dirty_nobuffers(bh->b_page);
 }
 
 /*
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 29b1d1e..e6fa69e 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -176,7 +176,7 @@ void bdi_writeout_inc(struct backing_dev_info *bdi)
 }
 EXPORT_SYMBOL_GPL(bdi_writeout_inc);
 
-static inline void task_dirty_inc(struct task_struct *tsk)
+static void task_dirty_inc(struct task_struct *tsk)
 {
 	prop_inc_single(&vm_dirties, &tsk->dirties);
 }
@@ -1074,12 +1074,14 @@ int __set_page_dirty_no_writeback(struct page *page)
  */
 int __set_page_dirty_nobuffers(struct page *page)
 {
-	if (!TestSetPageDirty(page)) {
-		struct address_space *mapping = page_mapping(page);
-		struct address_space *mapping2;
+	struct address_space *mapping;
 
-		if (!mapping)
-			return 1;
+	if (TestSetPageDirty(page))
+		return 0;
+
+	mapping = page_mapping(page);
+	if (likely(mapping)) {
+		struct address_space *mapping2;
 
 		spin_lock_irq(&mapping->tree_lock);
 		mapping2 = page_mapping(page);
@@ -1100,9 +1102,11 @@ int __set_page_dirty_nobuffers(struct page *page)
 			/* !PageAnon && !swapper_space */
 			__mark_inode_dirty(mapping->host, I_DIRTY_PAGES);
 		}
-		return 1;
 	}
-	return 0;
+
+	task_dirty_inc(current);
+
+	return 1;
 }
 EXPORT_SYMBOL(__set_page_dirty_nobuffers);
 
@@ -1122,7 +1126,7 @@ EXPORT_SYMBOL(redirty_page_for_writepage);
  * If the mapping doesn't provide a set_page_dirty a_op, then
  * just fall through and assume that it wants buffer_heads.
  */
-static int __set_page_dirty(struct page *page)
+int set_page_dirty(struct page *page)
 {
 	struct address_space *mapping = page_mapping(page);
 
@@ -1140,14 +1144,6 @@ static int __set_page_dirty(struct page *page)
 	}
 	return 0;
 }
-
-int set_page_dirty(struct page *page)
-{
-	int ret = __set_page_dirty(page);
-	if (ret)
-		task_dirty_inc(current);
-	return ret;
-}
 EXPORT_SYMBOL(set_page_dirty);
 
 /*