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Subject[PATCH][BUG] fix the calculation of the oldest_jif in wb_kupdate()
From: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>

wb_kupdate() function has a bug on linux-2.6.30-rc5.
This bug causes generic_sync_sb_inodes() to start to write inodes back
much earlier than our expectations because it miscalculates oldest_jif
in wb_kupdate().

Signed-off-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
---
page-writeback.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff -Nurp linux-2.6.30-rc5.orig/mm/page-writeback.c linux-2.6.30-rc5/mm/page-writeback.c
--- linux-2.6.30-rc5.orig/mm/page-writeback.c 2009-05-09 09:14:14.000000000 +0900
+++ linux-2.6.30-rc5/mm/page-writeback.c 2009-05-15 20:19:03.000000000 +0900
@@ -94,12 +94,12 @@ unsigned long vm_dirty_bytes;
/*
* The interval between `kupdate'-style writebacks
*/
-unsigned int dirty_writeback_interval = 5 * 100; /* sentiseconds */
+unsigned int dirty_writeback_interval = 5 * 100; /* centiseconds */

/*
* The longest time for which data is allowed to remain dirty
*/
-unsigned int dirty_expire_interval = 30 * 100; /* sentiseconds */
+unsigned int dirty_expire_interval = 30 * 100; /* centiseconds */

/*
* Flag that makes the machine dump writes/reads and block dirtyings.
@@ -770,7 +770,7 @@ static void wb_kupdate(unsigned long arg

sync_supers();

- oldest_jif = jiffies - msecs_to_jiffies(dirty_expire_interval);
+ oldest_jif = jiffies - msecs_to_jiffies(dirty_expire_interval * 10);
start_jif = jiffies;
next_jif = start_jif + msecs_to_jiffies(dirty_writeback_interval * 10);
nr_to_write = global_page_state(NR_FILE_DIRTY) +

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