Merge branch 'writeback' of git://git.kernel.dk/linux-2.6-block

* 'writeback' of git://git.kernel.dk/linux-2.6-block:
  writeback: writeback_inodes_sb() should use bdi_start_writeback()
  writeback: don't delay inodes redirtied by a fast dirtier
  writeback: make the super_block pinning more efficient
  writeback: don't resort for a single super_block in move_expired_inodes()
  writeback: move inodes from one super_block together
  writeback: get rid to incorrect references to pdflush in comments
  writeback: improve readability of the wb_writeback() continue/break logic
  writeback: cleanup writeback_single_inode()
  writeback: kupdate writeback shall not stop when more io is possible
  writeback: stop background writeback when below background threshold
  writeback: balance_dirty_pages() shall write more than dirtied pages
  fs: Fix busyloop in wb_writeback()

3 files changed, 24 insertions, 19 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index d99664e8607e..69b5fbabc8bd 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -44,18 +44,21 @@ static long ratelimit_pages = 32;
 /*
  * When balance_dirty_pages decides that the caller needs to perform some
  * non-background writeback, this is how many pages it will attempt to write.
- * It should be somewhat larger than RATELIMIT_PAGES to ensure that reasonably
+ * It should be somewhat larger than dirtied pages to ensure that reasonably
  * large amounts of I/O are submitted.
  */
-static inline long sync_writeback_pages(void)
+static inline long sync_writeback_pages(unsigned long dirtied)
 {
-        return ratelimit_pages + ratelimit_pages / 2;
+        if (dirtied < ratelimit_pages)
+                dirtied = ratelimit_pages;
+
+        return dirtied + dirtied / 2;
 }
 
 /* The following parameters are exported via /proc/sys/vm */
 
 /*
- * Start background writeback (via pdflush) at this percentage
+ * Start background writeback (via writeback threads) at this percentage
  */
 int dirty_background_ratio = 10;
 
@@ -474,10 +477,11 @@ get_dirty_limits(unsigned long *pbackground, unsigned long *pdirty,
  * balance_dirty_pages() must be called by processes which are generating dirty
  * data.  It looks at the number of dirty pages in the machine and will force
  * the caller to perform writeback if the system is over `vm_dirty_ratio'.
- * If we're over `background_thresh' then pdflush is woken to perform some
- * writeout.
+ * If we're over `background_thresh' then the writeback threads are woken to
+ * perform some writeout.
  */
-static void balance_dirty_pages(struct address_space *mapping)
+static void balance_dirty_pages(struct address_space *mapping,
+                                unsigned long write_chunk)
 {
         long nr_reclaimable, bdi_nr_reclaimable;
         long nr_writeback, bdi_nr_writeback;
@@ -485,7 +489,6 @@ static void balance_dirty_pages(struct address_space *mapping)
         unsigned long dirty_thresh;
         unsigned long bdi_thresh;
         unsigned long pages_written = 0;
-        unsigned long write_chunk = sync_writeback_pages();
         unsigned long pause = 1;
 
         struct backing_dev_info *bdi = mapping->backing_dev_info;
@@ -579,7 +582,7 @@ static void balance_dirty_pages(struct address_space *mapping)
                 bdi->dirty_exceeded = 0;
 
         if (writeback_in_progress(bdi))
-                return;         /* pdflush is already working this queue */
+                return;
 
         /*
          * In laptop mode, we wait until hitting the higher threshold before
@@ -590,10 +593,10 @@ static void balance_dirty_pages(struct address_space *mapping)
          * background_thresh, to keep the amount of dirty memory low.
          */
         if ((laptop_mode && pages_written) ||
-            (!laptop_mode && ((nr_writeback = global_page_state(NR_FILE_DIRTY)
-                                          + global_page_state(NR_UNSTABLE_NFS))
+            (!laptop_mode && ((global_page_state(NR_FILE_DIRTY)
+                               + global_page_state(NR_UNSTABLE_NFS))
                                           > background_thresh)))
-                bdi_start_writeback(bdi, nr_writeback);
+                bdi_start_writeback(bdi, 0);
 }
 
 void set_page_dirty_balance(struct page *page, int page_mkwrite)
@@ -640,9 +643,10 @@ void balance_dirty_pages_ratelimited_nr(struct address_space *mapping,
         p =  &__get_cpu_var(bdp_ratelimits);
         *p += nr_pages_dirtied;
         if (unlikely(*p >= ratelimit)) {
+                ratelimit = sync_writeback_pages(*p);
                 *p = 0;
                 preempt_enable();
-                balance_dirty_pages(mapping);
+                balance_dirty_pages(mapping, ratelimit);
                 return;
         }
         preempt_enable();
diff --git a/mm/shmem.c b/mm/shmem.c
index 98631c26c200..ccf446a9faa1 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1046,8 +1046,9 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
          * sync from ever calling shmem_writepage; but a stacking filesystem
          * may use the ->writepage of its underlying filesystem, in which case
          * tmpfs should write out to swap only in response to memory pressure,
-         * and not for pdflush or sync.  However, in those cases, we do still
-         * want to check if there's a redundant swappage to be discarded.
+         * and not for the writeback threads or sync.  However, in those cases,
+         * we do still want to check if there's a redundant swappage to be
+         * discarded.
          */
         if (wbc->for_reclaim)
                 swap = get_swap_page();
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1219ceb8a9b2..64e438898832 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1709,10 +1709,10 @@ static void shrink_zones(int priority, struct zonelist *zonelist,
  *
  * If the caller is !__GFP_FS then the probability of a failure is reasonably
  * high - the zone may be full of dirty or under-writeback pages, which this
- * caller can't do much about.  We kick pdflush and take explicit naps in the
- * hope that some of these pages can be written.  But if the allocating task
- * holds filesystem locks which prevent writeout this might not work, and the
- * allocation attempt will fail.
+ * caller can't do much about.  We kick the writeback threads and take explicit
+ * naps in the hope that some of these pages can be written.  But if the
+ * allocating task holds filesystem locks which prevent writeout this might not
+ * work, and the allocation attempt will fail.
  *
  * returns:     0, if no pages reclaimed
  *              else, the number of pages reclaimed