[PATCH 02/11] writeback: requeue_io_wait() on blocked kupdate

[Fengguang Wu <wfg@mail.ustc.edu.cn>]

Convert to requeue_io_wait() for case:

	kupdate cannot write all pages because of uncontrollable bad conditions.

Cc: Michael Rubin <mrubin@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
---
 fs/fs-writeback.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- linux-2.6.24-rc6-mm1.orig/fs/fs-writeback.c
+++ linux-2.6.24-rc6-mm1/fs/fs-writeback.c
@@ -292,11 +292,16 @@ __sync_single_inode(struct inode *inode,
 				 * For the kupdate function we move the inode
 				 * to s_more_io so it will get more writeout as
 				 * soon as the queue becomes uncongested.
 				 */
 				inode->i_state |= I_DIRTY_PAGES;
-				requeue_io(inode);
+				if (wbc->nr_to_write > 0)
+					/* somehow blocked: wait and retry */
+					requeue_io_wait(inode);
+				else
+					/* slice used up: queue for next turn */
+					requeue_io(inode);
 			} else {
 				/*
 				 * Otherwise fully redirty the inode so that
 				 * other inodes on this superblock will get some
 				 * writeout.  Otherwise heavy writing to one

-- 
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