From 55e829af06681e5d731c03ba04febbd1c76ca293 Mon Sep 17 00:00:00 2001
From: Andrew Morton <akpm@osdl.org>
Date: Sun, 10 Dec 2006 02:19:27 -0800
Subject: [PATCH] io-accounting: write accounting

Accounting writes is fairly simple: whenever a process flips a page from clean
to dirty, we accuse it of having caused a write to underlying storage of
PAGE_CACHE_SIZE bytes.

This may overestimate the amount of writing: the page-dirtying may cause only
one buffer_head's worth of writeout.  Fixing that is possible, but probably a
bit messy and isn't obviously important.

Cc: Jay Lan <jlan@sgi.com>
Cc: Shailabh Nagar <nagar@watson.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Chris Sturtivant <csturtiv@sgi.com>
Cc: Tony Ernst <tee@sgi.com>
Cc: Guillaume Thouvenin <guillaume.thouvenin@bull.net>
Cc: David Wright <daw@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
 fs/buffer.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

(limited to 'fs')

diff --git a/fs/buffer.c b/fs/buffer.c
index 865570fe0d39..904d59d1eb8e 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -35,6 +35,7 @@
 #include <linux/hash.h>
 #include <linux/suspend.h>
 #include <linux/buffer_head.h>
+#include <linux/task_io_accounting_ops.h>
 #include <linux/bio.h>
 #include <linux/notifier.h>
 #include <linux/cpu.h>
@@ -729,8 +730,10 @@ int __set_page_dirty_buffers(struct page *page)
 
 	write_lock_irq(&mapping->tree_lock);
 	if (page->mapping) {	/* Race with truncate? */
-		if (mapping_cap_account_dirty(mapping))
+		if (mapping_cap_account_dirty(mapping)) {
 			__inc_zone_page_state(page, NR_FILE_DIRTY);
+			task_io_account_write(PAGE_CACHE_SIZE);
+		}
 		radix_tree_tag_set(&mapping->page_tree,
 				page_index(page), PAGECACHE_TAG_DIRTY);
 	}
-- 
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