[PATCH] separate bdi congestion functions from queue congestion functions

Separate out the concept of "queue congestion" from "backing-dev congestion".
Congestion is a backing-dev concept, not a queue concept.

The blk_* congestion functions are retained, as wrappers around the core
backing-dev congestion functions.

This proper layering is needed so that NFS can cleanly use the congestion
functions, and so that CONFIG_BLOCK=n actually links.

Cc: "Thomas Maier" <balagi@justmail.de>
Cc: "Jens Axboe" <jens.axboe@oracle.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: David Howells <dhowells@redhat.com>
Cc: Peter Osterlund <petero2@telia.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 13 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index a0f339057449..8d9b19f239c3 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -222,7 +222,7 @@ static void balance_dirty_pages(struct address_space *mapping)
                         if (pages_written >= write_chunk)
                                 break;          /* We've done our duty */
                 }
-                blk_congestion_wait(WRITE, HZ/10);
+                congestion_wait(WRITE, HZ/10);
         }
 
         if (nr_reclaimable + global_page_state(NR_WRITEBACK)
@@ -314,7 +314,7 @@ void throttle_vm_writeout(void)
                 if (global_page_state(NR_UNSTABLE_NFS) +
                         global_page_state(NR_WRITEBACK) <= dirty_thresh)
                                 break;
-                blk_congestion_wait(WRITE, HZ/10);
+                congestion_wait(WRITE, HZ/10);
         }
 }
 
@@ -351,7 +351,7 @@ static void background_writeout(unsigned long _min_pages)
                 min_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
                 if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
                         /* Wrote less than expected */
-                        blk_congestion_wait(WRITE, HZ/10);
+                        congestion_wait(WRITE, HZ/10);
                         if (!wbc.encountered_congestion)
                                 break;
                 }
@@ -422,7 +422,7 @@ static void wb_kupdate(unsigned long arg)
                 writeback_inodes(&wbc);
                 if (wbc.nr_to_write > 0) {
                         if (wbc.encountered_congestion)
-                                blk_congestion_wait(WRITE, HZ/10);
+                                congestion_wait(WRITE, HZ/10);
                         else
                                 break;  /* All the old data is written */
                 }
@@ -956,15 +956,6 @@ int test_set_page_writeback(struct page *page)
 EXPORT_SYMBOL(test_set_page_writeback);
 
 /*
- * Wakes up tasks that are being throttled due to writeback congestion
- */
-void writeback_congestion_end(void)
-{
-        blk_congestion_end(WRITE);
-}
-EXPORT_SYMBOL(writeback_congestion_end);
-
-/*
  * Return true if any of the pages in the mapping are marged with the
  * passed tag.
  */