Introduce writeback_control.more_io to indicate that more I/O is
scheduled for this wakeup of pdflush.

Note that more_io is only updated on the _visited_ superblocks,
which prevents pdflush deamons from interfering with one another.

Cc: Michael Rubin <[EMAIL PROTECTED]>                                           
                                        
Cc: Peter Zijlstra <[EMAIL PROTECTED]>                                          
                                     
Signed-off-by: Fengguang Wu <[EMAIL PROTECTED]>
---
 fs/fs-writeback.c         |    6 +++++-
 include/linux/writeback.h |    1 +
 2 files changed, 6 insertions(+), 1 deletion(-)

--- linux-mm.orig/fs/fs-writeback.c
+++ linux-mm/fs/fs-writeback.c
@@ -472,8 +472,12 @@ int generic_sync_sb_inodes(struct super_
                iput(inode);
                cond_resched();
                spin_lock(&inode_lock);
-               if (wbc->nr_to_write <= 0)
+               if (wbc->nr_to_write <= 0) {
+                       wbc->more_io = 1;
                        break;
+               }
+               if (!list_empty(&sb->s_more_io))
+                       wbc->more_io = 1;
        }
        spin_unlock(&inode_lock);
        return ret;             /* Leave any unwritten inodes on s_io */
--- linux-mm.orig/include/linux/writeback.h
+++ linux-mm/include/linux/writeback.h
@@ -62,6 +62,7 @@ struct writeback_control {
        unsigned for_reclaim:1;         /* Invoked from the page allocator */
        unsigned for_writepages:1;      /* This is a writepages() call */
        unsigned range_cyclic:1;        /* range_start is cyclic */
+       unsigned more_io:1;             /* more io to be dispatched */
 };
 
 /*

-- 
-
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