[PATCH] io-accounting: write-cancel accounting

Account for the number of byte writes which this process caused to not happen
after all.

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>

2 files changed, 9 insertions, 2 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index 904d59d1eb8e..d1f1b54d3108 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2853,8 +2853,13 @@ int try_to_free_buffers(struct page *page)
                  * could encounter a non-uptodate page, which is unresolvable.
                  * This only applies in the rare case where try_to_free_buffers
                  * succeeds but the page is not freed.
+                 *
+                 * Also, during truncate, discard_buffer will have marked all
+                 * the page's buffers clean.  We discover that here and clean
+                 * the page also.
                  */
-                clear_page_dirty(page);
+                if (test_clear_page_dirty(page))
+                        task_io_account_cancelled_write(PAGE_CACHE_SIZE);
         }
 out:
         if (buffers_to_free) {
diff --git a/mm/truncate.c b/mm/truncate.c
index e07b1e682c38..9bfb8e853860 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -13,6 +13,7 @@
 #include <linux/module.h>
 #include <linux/pagemap.h>
 #include <linux/pagevec.h>
+#include <linux/task_io_accounting_ops.h>
 #include <linux/buffer_head.h>  /* grr. try_to_release_page,
                                    do_invalidatepage */
 
@@ -69,7 +70,8 @@ truncate_complete_page(struct address_space *mapping, struct page *page)
         if (PagePrivate(page))
                 do_invalidatepage(page, 0);
 
-        clear_page_dirty(page);
+        if (test_clear_page_dirty(page))
+                task_io_account_cancelled_write(PAGE_CACHE_SIZE);
         ClearPageUptodate(page);
         ClearPageMappedToDisk(page);
         remove_from_page_cache(page);