We don't want to introduce pointless delays in throttle_vm_writeout()
when the writeback limits are not yet exceeded, do we?

Cc: Nick Piggin <[EMAIL PROTECTED]>
Cc: OGAWA Hirofumi <[EMAIL PROTECTED]>
Cc: Kumar Gala <[EMAIL PROTECTED]>
Cc: Pete Zaitcev <[EMAIL PROTECTED]>
Cc: Greg KH <[EMAIL PROTECTED]>
Signed-off-by: Fengguang Wu <[EMAIL PROTECTED]>
---
 mm/page-writeback.c |   18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

--- linux-2.6.23-rc8-mm1.orig/mm/page-writeback.c
+++ linux-2.6.23-rc8-mm1/mm/page-writeback.c
@@ -507,16 +507,6 @@ void throttle_vm_writeout(gfp_t gfp_mask
        long background_thresh;
        long dirty_thresh;
 
-       if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO)) {
-               /*
-                * The caller might hold locks which can prevent IO completion
-                * or progress in the filesystem.  So we cannot just sit here
-                * waiting for IO to complete.
-                */
-               congestion_wait(WRITE, HZ/10);
-               return;
-       }
-
         for ( ; ; ) {
                get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL);
 
@@ -530,6 +520,14 @@ void throttle_vm_writeout(gfp_t gfp_mask
                        global_page_state(NR_WRITEBACK) <= dirty_thresh)
                                break;
                 congestion_wait(WRITE, HZ/10);
+
+               /*
+                * The caller might hold locks which can prevent IO completion
+                * or progress in the filesystem.  So we cannot just sit here
+                * waiting for IO to complete.
+                */
+               if ((gfp_mask & (__GFP_FS|__GFP_IO)) != (__GFP_FS|__GFP_IO))
+                       break;
         }
 }
 

-
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