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

* 'writeback' of git://git.kernel.dk/linux-2.6-block:
  writeback: check for registered bdi in flusher add and inode dirty
  writeback: add name to backing_dev_info
  writeback: add some debug inode list counters to bdi stats
  writeback: get rid of pdflush completely
  writeback: switch to per-bdi threads for flushing data
  writeback: move dirty inodes from super_block to backing_dev_info
  writeback: get rid of generic_sync_sb_inodes() export

6 files changed, 405 insertions, 432 deletions

diff --git a/mm/Makefile b/mm/Makefile
index 5e0bd6426693..147a7a7873c4 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -8,7 +8,7 @@ mmu-$(CONFIG_MMU)	:= fremap.o highmem.o madvise.o memory.o mincore.o \
                            vmalloc.o
 
 obj-y                   := bootmem.o filemap.o mempool.o oom_kill.o fadvise.o \
-                           maccess.o page_alloc.o page-writeback.o pdflush.o \
+                           maccess.o page_alloc.o page-writeback.o \
                            readahead.o swap.o truncate.o vmscan.o shmem.o \
                            prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \
                            page_isolation.o mm_init.o $(mmu-y)
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index c86edd244294..d3ca0dac1111 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -1,8 +1,11 @@
 
 #include <linux/wait.h>
 #include <linux/backing-dev.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
 #include <linux/fs.h>
 #include <linux/pagemap.h>
+#include <linux/mm.h>
 #include <linux/sched.h>
 #include <linux/module.h>
 #include <linux/writeback.h>
@@ -14,6 +17,7 @@ void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
 EXPORT_SYMBOL(default_unplug_io_fn);
 
 struct backing_dev_info default_backing_dev_info = {
+        .name           = "default",
         .ra_pages       = VM_MAX_READAHEAD * 1024 / PAGE_CACHE_SIZE,
         .state          = 0,
         .capabilities   = BDI_CAP_MAP_COPY,
@@ -22,6 +26,18 @@ struct backing_dev_info default_backing_dev_info = {
 EXPORT_SYMBOL_GPL(default_backing_dev_info);
 
 static struct class *bdi_class;
+DEFINE_SPINLOCK(bdi_lock);
+LIST_HEAD(bdi_list);
+LIST_HEAD(bdi_pending_list);
+
+static struct task_struct *sync_supers_tsk;
+static struct timer_list sync_supers_timer;
+
+static int bdi_sync_supers(void *);
+static void sync_supers_timer_fn(unsigned long);
+static void arm_supers_timer(void);
+
+static void bdi_add_default_flusher_task(struct backing_dev_info *bdi);
 
 #ifdef CONFIG_DEBUG_FS
 #include <linux/debugfs.h>
@@ -37,9 +53,29 @@ static void bdi_debug_init(void)
 static int bdi_debug_stats_show(struct seq_file *m, void *v)
 {
         struct backing_dev_info *bdi = m->private;
+        struct bdi_writeback *wb;
         unsigned long background_thresh;
         unsigned long dirty_thresh;
         unsigned long bdi_thresh;
+        unsigned long nr_dirty, nr_io, nr_more_io, nr_wb;
+        struct inode *inode;
+
+        /*
+         * inode lock is enough here, the bdi->wb_list is protected by
+         * RCU on the reader side
+         */
+        nr_wb = nr_dirty = nr_io = nr_more_io = 0;
+        spin_lock(&inode_lock);
+        list_for_each_entry(wb, &bdi->wb_list, list) {
+                nr_wb++;
+                list_for_each_entry(inode, &wb->b_dirty, i_list)
+                        nr_dirty++;
+                list_for_each_entry(inode, &wb->b_io, i_list)
+                        nr_io++;
+                list_for_each_entry(inode, &wb->b_more_io, i_list)
+                        nr_more_io++;
+        }
+        spin_unlock(&inode_lock);
 
         get_dirty_limits(&background_thresh, &dirty_thresh, &bdi_thresh, bdi);
 
@@ -49,12 +85,22 @@ static int bdi_debug_stats_show(struct seq_file *m, void *v)
                    "BdiReclaimable:   %8lu kB\n"
                    "BdiDirtyThresh:   %8lu kB\n"
                    "DirtyThresh:      %8lu kB\n"
-                   "BackgroundThresh: %8lu kB\n",
+                   "BackgroundThresh: %8lu kB\n"
+                   "WriteBack threads:%8lu\n"
+                   "b_dirty:          %8lu\n"
+                   "b_io:             %8lu\n"
+                   "b_more_io:        %8lu\n"
+                   "bdi_list:         %8u\n"
+                   "state:            %8lx\n"
+                   "wb_mask:          %8lx\n"
+                   "wb_list:          %8u\n"
+                   "wb_cnt:           %8u\n",
                    (unsigned long) K(bdi_stat(bdi, BDI_WRITEBACK)),
                    (unsigned long) K(bdi_stat(bdi, BDI_RECLAIMABLE)),
-                   K(bdi_thresh),
-                   K(dirty_thresh),
-                   K(background_thresh));
+                   K(bdi_thresh), K(dirty_thresh),
+                   K(background_thresh), nr_wb, nr_dirty, nr_io, nr_more_io,
+                   !list_empty(&bdi->bdi_list), bdi->state, bdi->wb_mask,
+                   !list_empty(&bdi->wb_list), bdi->wb_cnt);
 #undef K
 
         return 0;
@@ -185,6 +231,13 @@ static int __init default_bdi_init(void)
 {
         int err;
 
+        sync_supers_tsk = kthread_run(bdi_sync_supers, NULL, "sync_supers");
+        BUG_ON(IS_ERR(sync_supers_tsk));
+
+        init_timer(&sync_supers_timer);
+        setup_timer(&sync_supers_timer, sync_supers_timer_fn, 0);
+        arm_supers_timer();
+
         err = bdi_init(&default_backing_dev_info);
         if (!err)
                 bdi_register(&default_backing_dev_info, NULL, "default");
@@ -193,6 +246,248 @@ static int __init default_bdi_init(void)
 }
 subsys_initcall(default_bdi_init);
 
+static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
+{
+        memset(wb, 0, sizeof(*wb));
+
+        wb->bdi = bdi;
+        wb->last_old_flush = jiffies;
+        INIT_LIST_HEAD(&wb->b_dirty);
+        INIT_LIST_HEAD(&wb->b_io);
+        INIT_LIST_HEAD(&wb->b_more_io);
+}
+
+static void bdi_task_init(struct backing_dev_info *bdi,
+                          struct bdi_writeback *wb)
+{
+        struct task_struct *tsk = current;
+
+        spin_lock(&bdi->wb_lock);
+        list_add_tail_rcu(&wb->list, &bdi->wb_list);
+        spin_unlock(&bdi->wb_lock);
+
+        tsk->flags |= PF_FLUSHER | PF_SWAPWRITE;
+        set_freezable();
+
+        /*
+         * Our parent may run at a different priority, just set us to normal
+         */
+        set_user_nice(tsk, 0);
+}
+
+static int bdi_start_fn(void *ptr)
+{
+        struct bdi_writeback *wb = ptr;
+        struct backing_dev_info *bdi = wb->bdi;
+        int ret;
+
+        /*
+         * Add us to the active bdi_list
+         */
+        spin_lock(&bdi_lock);
+        list_add(&bdi->bdi_list, &bdi_list);
+        spin_unlock(&bdi_lock);
+
+        bdi_task_init(bdi, wb);
+
+        /*
+         * Clear pending bit and wakeup anybody waiting to tear us down
+         */
+        clear_bit(BDI_pending, &bdi->state);
+        smp_mb__after_clear_bit();
+        wake_up_bit(&bdi->state, BDI_pending);
+
+        ret = bdi_writeback_task(wb);
+
+        /*
+         * Remove us from the list
+         */
+        spin_lock(&bdi->wb_lock);
+        list_del_rcu(&wb->list);
+        spin_unlock(&bdi->wb_lock);
+
+        /*
+         * Flush any work that raced with us exiting. No new work
+         * will be added, since this bdi isn't discoverable anymore.
+         */
+        if (!list_empty(&bdi->work_list))
+                wb_do_writeback(wb, 1);
+
+        wb->task = NULL;
+        return ret;
+}
+
+int bdi_has_dirty_io(struct backing_dev_info *bdi)
+{
+        return wb_has_dirty_io(&bdi->wb);
+}
+
+static void bdi_flush_io(struct backing_dev_info *bdi)
+{
+        struct writeback_control wbc = {
+                .bdi                    = bdi,
+                .sync_mode              = WB_SYNC_NONE,
+                .older_than_this        = NULL,
+                .range_cyclic           = 1,
+                .nr_to_write            = 1024,
+        };
+
+        writeback_inodes_wbc(&wbc);
+}
+
+/*
+ * kupdated() used to do this. We cannot do it from the bdi_forker_task()
+ * or we risk deadlocking on ->s_umount. The longer term solution would be
+ * to implement sync_supers_bdi() or similar and simply do it from the
+ * bdi writeback tasks individually.
+ */
+static int bdi_sync_supers(void *unused)
+{
+        set_user_nice(current, 0);
+
+        while (!kthread_should_stop()) {
+                set_current_state(TASK_INTERRUPTIBLE);
+                schedule();
+
+                /*
+                 * Do this periodically, like kupdated() did before.
+                 */
+                sync_supers();
+        }
+
+        return 0;
+}
+
+static void arm_supers_timer(void)
+{
+        unsigned long next;
+
+        next = msecs_to_jiffies(dirty_writeback_interval * 10) + jiffies;
+        mod_timer(&sync_supers_timer, round_jiffies_up(next));
+}
+
+static void sync_supers_timer_fn(unsigned long unused)
+{
+        wake_up_process(sync_supers_tsk);
+        arm_supers_timer();
+}
+
+static int bdi_forker_task(void *ptr)
+{
+        struct bdi_writeback *me = ptr;
+
+        bdi_task_init(me->bdi, me);
+
+        for (;;) {
+                struct backing_dev_info *bdi, *tmp;
+                struct bdi_writeback *wb;
+
+                /*
+                 * Temporary measure, we want to make sure we don't see
+                 * dirty data on the default backing_dev_info
+                 */
+                if (wb_has_dirty_io(me) || !list_empty(&me->bdi->work_list))
+                        wb_do_writeback(me, 0);
+
+                spin_lock(&bdi_lock);
+
+                /*
+                 * Check if any existing bdi's have dirty data without
+                 * a thread registered. If so, set that up.
+                 */
+                list_for_each_entry_safe(bdi, tmp, &bdi_list, bdi_list) {
+                        if (bdi->wb.task)
+                                continue;
+                        if (list_empty(&bdi->work_list) &&
+                            !bdi_has_dirty_io(bdi))
+                                continue;
+
+                        bdi_add_default_flusher_task(bdi);
+                }
+
+                set_current_state(TASK_INTERRUPTIBLE);
+
+                if (list_empty(&bdi_pending_list)) {
+                        unsigned long wait;
+
+                        spin_unlock(&bdi_lock);
+                        wait = msecs_to_jiffies(dirty_writeback_interval * 10);
+                        schedule_timeout(wait);
+                        try_to_freeze();
+                        continue;
+                }
+
+                __set_current_state(TASK_RUNNING);
+
+                /*
+                 * This is our real job - check for pending entries in
+                 * bdi_pending_list, and create the tasks that got added
+                 */
+                bdi = list_entry(bdi_pending_list.next, struct backing_dev_info,
+                                 bdi_list);
+                list_del_init(&bdi->bdi_list);
+                spin_unlock(&bdi_lock);
+
+                wb = &bdi->wb;
+                wb->task = kthread_run(bdi_start_fn, wb, "flush-%s",
+                                        dev_name(bdi->dev));
+                /*
+                 * If task creation fails, then readd the bdi to
+                 * the pending list and force writeout of the bdi
+                 * from this forker thread. That will free some memory
+                 * and we can try again.
+                 */
+                if (IS_ERR(wb->task)) {
+                        wb->task = NULL;
+
+                        /*
+                         * Add this 'bdi' to the back, so we get
+                         * a chance to flush other bdi's to free
+                         * memory.
+                         */
+                        spin_lock(&bdi_lock);
+                        list_add_tail(&bdi->bdi_list, &bdi_pending_list);
+                        spin_unlock(&bdi_lock);
+
+                        bdi_flush_io(bdi);
+                }
+        }
+
+        return 0;
+}
+
+/*
+ * Add the default flusher task that gets created for any bdi
+ * that has dirty data pending writeout
+ */
+void static bdi_add_default_flusher_task(struct backing_dev_info *bdi)
+{
+        if (!bdi_cap_writeback_dirty(bdi))
+                return;
+
+        if (WARN_ON(!test_bit(BDI_registered, &bdi->state))) {
+                printk(KERN_ERR "bdi %p/%s is not registered!\n",
+                                                        bdi, bdi->name);
+                return;
+        }
+
+        /*
+         * Check with the helper whether to proceed adding a task. Will only
+         * abort if we two or more simultanous calls to
+         * bdi_add_default_flusher_task() occured, further additions will block
+         * waiting for previous additions to finish.
+         */
+        if (!test_and_set_bit(BDI_pending, &bdi->state)) {
+                list_move_tail(&bdi->bdi_list, &bdi_pending_list);
+
+                /*
+                 * We are now on the pending list, wake up bdi_forker_task()
+                 * to finish the job and add us back to the active bdi_list
+                 */
+                wake_up_process(default_backing_dev_info.wb.task);
+        }
+}
+
 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
                 const char *fmt, ...)
 {
@@ -211,9 +506,35 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
                 goto exit;
         }
 
+        spin_lock(&bdi_lock);
+        list_add_tail(&bdi->bdi_list, &bdi_list);
+        spin_unlock(&bdi_lock);
+
         bdi->dev = dev;
-        bdi_debug_register(bdi, dev_name(dev));
 
+        /*
+         * Just start the forker thread for our default backing_dev_info,
+         * and add other bdi's to the list. They will get a thread created
+         * on-demand when they need it.
+         */
+        if (bdi_cap_flush_forker(bdi)) {
+                struct bdi_writeback *wb = &bdi->wb;
+
+                wb->task = kthread_run(bdi_forker_task, wb, "bdi-%s",
+                                                dev_name(dev));
+                if (IS_ERR(wb->task)) {
+                        wb->task = NULL;
+                        ret = -ENOMEM;
+
+                        spin_lock(&bdi_lock);
+                        list_del(&bdi->bdi_list);
+                        spin_unlock(&bdi_lock);
+                        goto exit;
+                }
+        }
+
+        bdi_debug_register(bdi, dev_name(dev));
+        set_bit(BDI_registered, &bdi->state);
 exit:
         return ret;
 }
@@ -225,9 +546,42 @@ int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev)
 }
 EXPORT_SYMBOL(bdi_register_dev);
 
+/*
+ * Remove bdi from the global list and shutdown any threads we have running
+ */
+static void bdi_wb_shutdown(struct backing_dev_info *bdi)
+{
+        struct bdi_writeback *wb;
+
+        if (!bdi_cap_writeback_dirty(bdi))
+                return;
+
+        /*
+         * If setup is pending, wait for that to complete first
+         */
+        wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait,
+                        TASK_UNINTERRUPTIBLE);
+
+        /*
+         * Make sure nobody finds us on the bdi_list anymore
+         */
+        spin_lock(&bdi_lock);
+        list_del(&bdi->bdi_list);
+        spin_unlock(&bdi_lock);
+
+        /*
+         * Finally, kill the kernel threads. We don't need to be RCU
+         * safe anymore, since the bdi is gone from visibility.
+         */
+        list_for_each_entry(wb, &bdi->wb_list, list)
+                kthread_stop(wb->task);
+}
+
 void bdi_unregister(struct backing_dev_info *bdi)
 {
         if (bdi->dev) {
+                if (!bdi_cap_flush_forker(bdi))
+                        bdi_wb_shutdown(bdi);
                 bdi_debug_unregister(bdi);
                 device_unregister(bdi->dev);
                 bdi->dev = NULL;
@@ -237,14 +591,25 @@ EXPORT_SYMBOL(bdi_unregister);
 
 int bdi_init(struct backing_dev_info *bdi)
 {
-        int i;
-        int err;
+        int i, err;
 
         bdi->dev = NULL;
 
         bdi->min_ratio = 0;
         bdi->max_ratio = 100;
         bdi->max_prop_frac = PROP_FRAC_BASE;
+        spin_lock_init(&bdi->wb_lock);
+        INIT_LIST_HEAD(&bdi->bdi_list);
+        INIT_LIST_HEAD(&bdi->wb_list);
+        INIT_LIST_HEAD(&bdi->work_list);
+
+        bdi_wb_init(&bdi->wb, bdi);
+
+        /*
+         * Just one thread support for now, hard code mask and count
+         */
+        bdi->wb_mask = 1;
+        bdi->wb_cnt = 1;
 
         for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
                 err = percpu_counter_init(&bdi->bdi_stat[i], 0);
@@ -269,6 +634,8 @@ void bdi_destroy(struct backing_dev_info *bdi)
 {
         int i;
 
+        WARN_ON(bdi_has_dirty_io(bdi));
+
         bdi_unregister(bdi);
 
         for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 81627ebcd313..25e7770309b8 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -36,15 +36,6 @@
 #include <linux/pagevec.h>
 
 /*
- * The maximum number of pages to writeout in a single bdflush/kupdate
- * operation.  We do this so we don't hold I_SYNC against an inode for
- * enormous amounts of time, which would block a userspace task which has
- * been forced to throttle against that inode.  Also, the code reevaluates
- * the dirty each time it has written this many pages.
- */
-#define MAX_WRITEBACK_PAGES     1024
-
-/*
  * After a CPU has dirtied this many pages, balance_dirty_pages_ratelimited
  * will look to see if it needs to force writeback or throttling.
  */
@@ -117,8 +108,6 @@ EXPORT_SYMBOL(laptop_mode);
 /* End of sysctl-exported parameters */
 
 
-static void background_writeout(unsigned long _min_pages);
-
 /*
  * Scale the writeback cache size proportional to the relative writeout speeds.
  *
@@ -320,15 +309,13 @@ static void task_dirty_limit(struct task_struct *tsk, unsigned long *pdirty)
 /*
  *
  */
-static DEFINE_SPINLOCK(bdi_lock);
 static unsigned int bdi_min_ratio;
 
 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio)
 {
         int ret = 0;
-        unsigned long flags;
 
-        spin_lock_irqsave(&bdi_lock, flags);
+        spin_lock(&bdi_lock);
         if (min_ratio > bdi->max_ratio) {
                 ret = -EINVAL;
         } else {
@@ -340,27 +327,26 @@ int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio)
                         ret = -EINVAL;
                 }
         }
-        spin_unlock_irqrestore(&bdi_lock, flags);
+        spin_unlock(&bdi_lock);
 
         return ret;
 }
 
 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned max_ratio)
 {
-        unsigned long flags;
         int ret = 0;
 
         if (max_ratio > 100)
                 return -EINVAL;
 
-        spin_lock_irqsave(&bdi_lock, flags);
+        spin_lock(&bdi_lock);
         if (bdi->min_ratio > max_ratio) {
                 ret = -EINVAL;
         } else {
                 bdi->max_ratio = max_ratio;
                 bdi->max_prop_frac = (PROP_FRAC_BASE * max_ratio) / 100;
         }
-        spin_unlock_irqrestore(&bdi_lock, flags);
+        spin_unlock(&bdi_lock);
 
         return ret;
 }
@@ -546,7 +532,7 @@ static void balance_dirty_pages(struct address_space *mapping)
                  * up.
                  */
                 if (bdi_nr_reclaimable > bdi_thresh) {
-                        writeback_inodes(&wbc);
+                        writeback_inodes_wbc(&wbc);
                         pages_written += write_chunk - wbc.nr_to_write;
                         get_dirty_limits(&background_thresh, &dirty_thresh,
                                        &bdi_thresh, bdi);
@@ -575,7 +561,7 @@ static void balance_dirty_pages(struct address_space *mapping)
                 if (pages_written >= write_chunk)
                         break;          /* We've done our duty */
 
-                congestion_wait(BLK_RW_ASYNC, HZ/10);
+                schedule_timeout(1);
         }
 
         if (bdi_nr_reclaimable + bdi_nr_writeback < bdi_thresh &&
@@ -594,10 +580,18 @@ 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 && (global_page_state(NR_FILE_DIRTY)
-                                          + global_page_state(NR_UNSTABLE_NFS)
-                                          > background_thresh)))
-                pdflush_operation(background_writeout, 0);
+            (!laptop_mode && ((nr_writeback = global_page_state(NR_FILE_DIRTY)
+                                          + global_page_state(NR_UNSTABLE_NFS))
+                                          > background_thresh))) {
+                struct writeback_control wbc = {
+                        .bdi            = bdi,
+                        .sync_mode      = WB_SYNC_NONE,
+                        .nr_to_write    = nr_writeback,
+                };
+
+
+                bdi_start_writeback(&wbc);
+        }
 }
 
 void set_page_dirty_balance(struct page *page, int page_mkwrite)
@@ -681,153 +675,35 @@ void throttle_vm_writeout(gfp_t gfp_mask)
         }
 }
 
-/*
- * writeback at least _min_pages, and keep writing until the amount of dirty
- * memory is less than the background threshold, or until we're all clean.
- */
-static void background_writeout(unsigned long _min_pages)
-{
-        long min_pages = _min_pages;
-        struct writeback_control wbc = {
-                .bdi            = NULL,
-                .sync_mode      = WB_SYNC_NONE,
-                .older_than_this = NULL,
-                .nr_to_write    = 0,
-                .nonblocking    = 1,
-                .range_cyclic   = 1,
-        };
-
-        for ( ; ; ) {
-                unsigned long background_thresh;
-                unsigned long dirty_thresh;
-
-                get_dirty_limits(&background_thresh, &dirty_thresh, NULL, NULL);
-                if (global_page_state(NR_FILE_DIRTY) +
-                        global_page_state(NR_UNSTABLE_NFS) < background_thresh
-                                && min_pages <= 0)
-                        break;
-                wbc.more_io = 0;
-                wbc.encountered_congestion = 0;
-                wbc.nr_to_write = MAX_WRITEBACK_PAGES;
-                wbc.pages_skipped = 0;
-                writeback_inodes(&wbc);
-                min_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
-                if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
-                        /* Wrote less than expected */
-                        if (wbc.encountered_congestion || wbc.more_io)
-                                congestion_wait(BLK_RW_ASYNC, HZ/10);
-                        else
-                                break;
-                }
-        }
-}
-
-/*
- * Start writeback of `nr_pages' pages.  If `nr_pages' is zero, write back
- * the whole world.  Returns 0 if a pdflush thread was dispatched.  Returns
- * -1 if all pdflush threads were busy.
- */
-int wakeup_pdflush(long nr_pages)
-{
-        if (nr_pages == 0)
-                nr_pages = global_page_state(NR_FILE_DIRTY) +
-                                global_page_state(NR_UNSTABLE_NFS);
-        return pdflush_operation(background_writeout, nr_pages);
-}
-
-static void wb_timer_fn(unsigned long unused);
 static void laptop_timer_fn(unsigned long unused);
 
-static DEFINE_TIMER(wb_timer, wb_timer_fn, 0, 0);
 static DEFINE_TIMER(laptop_mode_wb_timer, laptop_timer_fn, 0, 0);
 
 /*
- * Periodic writeback of "old" data.
- *
- * Define "old": the first time one of an inode's pages is dirtied, we mark the
- * dirtying-time in the inode's address_space.  So this periodic writeback code
- * just walks the superblock inode list, writing back any inodes which are
- * older than a specific point in time.
- *
- * Try to run once per dirty_writeback_interval.  But if a writeback event
- * takes longer than a dirty_writeback_interval interval, then leave a
- * one-second gap.
- *
- * older_than_this takes precedence over nr_to_write.  So we'll only write back
- * all dirty pages if they are all attached to "old" mappings.
- */
-static void wb_kupdate(unsigned long arg)
-{
-        unsigned long oldest_jif;
-        unsigned long start_jif;
-        unsigned long next_jif;
-        long nr_to_write;
-        struct writeback_control wbc = {
-                .bdi            = NULL,
-                .sync_mode      = WB_SYNC_NONE,
-                .older_than_this = &oldest_jif,
-                .nr_to_write    = 0,
-                .nonblocking    = 1,
-                .for_kupdate    = 1,
-                .range_cyclic   = 1,
-        };
-
-        sync_supers();
-
-        oldest_jif = jiffies - msecs_to_jiffies(dirty_expire_interval * 10);
-        start_jif = jiffies;
-        next_jif = start_jif + msecs_to_jiffies(dirty_writeback_interval * 10);
-        nr_to_write = global_page_state(NR_FILE_DIRTY) +
-                        global_page_state(NR_UNSTABLE_NFS) +
-                        (inodes_stat.nr_inodes - inodes_stat.nr_unused);
-        while (nr_to_write > 0) {
-                wbc.more_io = 0;
-                wbc.encountered_congestion = 0;
-                wbc.nr_to_write = MAX_WRITEBACK_PAGES;
-                writeback_inodes(&wbc);
-                if (wbc.nr_to_write > 0) {
-                        if (wbc.encountered_congestion || wbc.more_io)
-                                congestion_wait(BLK_RW_ASYNC, HZ/10);
-                        else
-                                break;  /* All the old data is written */
-                }
-                nr_to_write -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
-        }
-        if (time_before(next_jif, jiffies + HZ))
-                next_jif = jiffies + HZ;
-        if (dirty_writeback_interval)
-                mod_timer(&wb_timer, next_jif);
-}
-
-/*
  * sysctl handler for /proc/sys/vm/dirty_writeback_centisecs
  */
 int dirty_writeback_centisecs_handler(ctl_table *table, int write,
         struct file *file, void __user *buffer, size_t *length, loff_t *ppos)
 {
         proc_dointvec(table, write, file, buffer, length, ppos);
-        if (dirty_writeback_interval)
-                mod_timer(&wb_timer, jiffies +
-                        msecs_to_jiffies(dirty_writeback_interval * 10));
-        else
-                del_timer(&wb_timer);
         return 0;
 }
 
-static void wb_timer_fn(unsigned long unused)
-{
-        if (pdflush_operation(wb_kupdate, 0) < 0)
-                mod_timer(&wb_timer, jiffies + HZ); /* delay 1 second */
-}
-
-static void laptop_flush(unsigned long unused)
+static void do_laptop_sync(struct work_struct *work)
 {
-        sys_sync();
+        wakeup_flusher_threads(0);
+        kfree(work);
 }
 
 static void laptop_timer_fn(unsigned long unused)
 {
-        pdflush_operation(laptop_flush, 0);
+        struct work_struct *work;
+
+        work = kmalloc(sizeof(*work), GFP_ATOMIC);
+        if (work) {
+                INIT_WORK(work, do_laptop_sync);
+                schedule_work(work);
+        }
 }
 
 /*
@@ -910,8 +786,6 @@ void __init page_writeback_init(void)
 {
         int shift;
 
-        mod_timer(&wb_timer,
-                  jiffies + msecs_to_jiffies(dirty_writeback_interval * 10));
         writeback_set_ratelimit();
         register_cpu_notifier(&ratelimit_nb);
 
diff --git a/mm/pdflush.c b/mm/pdflush.c
deleted file mode 100644
index 235ac440c44e..000000000000
--- a/mm/pdflush.c
+++ /dev/null
@@ -1,269 +0,0 @@
-/*
- * mm/pdflush.c - worker threads for writing back filesystem data
- *
- * Copyright (C) 2002, Linus Torvalds.
- *
- * 09Apr2002    Andrew Morton
- *              Initial version
- * 29Feb2004    kaos@sgi.com
- *              Move worker thread creation to kthread to avoid chewing
- *              up stack space with nested calls to kernel_thread.
- */
-
-#include <linux/sched.h>
-#include <linux/list.h>
-#include <linux/signal.h>
-#include <linux/spinlock.h>
-#include <linux/gfp.h>
-#include <linux/init.h>
-#include <linux/module.h>
-#include <linux/fs.h>           /* Needed by writeback.h          */
-#include <linux/writeback.h>    /* Prototypes pdflush_operation() */
-#include <linux/kthread.h>
-#include <linux/cpuset.h>
-#include <linux/freezer.h>
-
-
-/*
- * Minimum and maximum number of pdflush instances
- */
-#define MIN_PDFLUSH_THREADS     2
-#define MAX_PDFLUSH_THREADS     8
-
-static void start_one_pdflush_thread(void);
-
-
-/*
- * The pdflush threads are worker threads for writing back dirty data.
- * Ideally, we'd like one thread per active disk spindle.  But the disk
- * topology is very hard to divine at this level.   Instead, we take
- * care in various places to prevent more than one pdflush thread from
- * performing writeback against a single filesystem.  pdflush threads
- * have the PF_FLUSHER flag set in current->flags to aid in this.
- */
-
-/*
- * All the pdflush threads.  Protected by pdflush_lock
- */
-static LIST_HEAD(pdflush_list);
-static DEFINE_SPINLOCK(pdflush_lock);
-
-/*
- * The count of currently-running pdflush threads.  Protected
- * by pdflush_lock.
- *
- * Readable by sysctl, but not writable.  Published to userspace at
- * /proc/sys/vm/nr_pdflush_threads.
- */
-int nr_pdflush_threads = 0;
-
-/*
- * The time at which the pdflush thread pool last went empty
- */
-static unsigned long last_empty_jifs;
-
-/*
- * The pdflush thread.
- *
- * Thread pool management algorithm:
- * 
- * - The minimum and maximum number of pdflush instances are bound
- *   by MIN_PDFLUSH_THREADS and MAX_PDFLUSH_THREADS.
- * 
- * - If there have been no idle pdflush instances for 1 second, create
- *   a new one.
- * 
- * - If the least-recently-went-to-sleep pdflush thread has been asleep
- *   for more than one second, terminate a thread.
- */
-
-/*
- * A structure for passing work to a pdflush thread.  Also for passing
- * state information between pdflush threads.  Protected by pdflush_lock.
- */
-struct pdflush_work {
-        struct task_struct *who;        /* The thread */
-        void (*fn)(unsigned long);      /* A callback function */
-        unsigned long arg0;             /* An argument to the callback */
-        struct list_head list;          /* On pdflush_list, when idle */
-        unsigned long when_i_went_to_sleep;
-};
-
-static int __pdflush(struct pdflush_work *my_work)
-{
-        current->flags |= PF_FLUSHER | PF_SWAPWRITE;
-        set_freezable();
-        my_work->fn = NULL;
-        my_work->who = current;
-        INIT_LIST_HEAD(&my_work->list);
-
-        spin_lock_irq(&pdflush_lock);
-        for ( ; ; ) {
-                struct pdflush_work *pdf;
-
-                set_current_state(TASK_INTERRUPTIBLE);
-                list_move(&my_work->list, &pdflush_list);
-                my_work->when_i_went_to_sleep = jiffies;
-                spin_unlock_irq(&pdflush_lock);
-                schedule();
-                try_to_freeze();
-                spin_lock_irq(&pdflush_lock);
-                if (!list_empty(&my_work->list)) {
-                        /*
-                         * Someone woke us up, but without removing our control
-                         * structure from the global list.  swsusp will do this
-                         * in try_to_freeze()->refrigerator().  Handle it.
-                         */
-                        my_work->fn = NULL;
-                        continue;
-                }
-                if (my_work->fn == NULL) {
-                        printk("pdflush: bogus wakeup\n");
-                        continue;
-                }
-                spin_unlock_irq(&pdflush_lock);
-
-                (*my_work->fn)(my_work->arg0);
-
-                spin_lock_irq(&pdflush_lock);
-
-                /*
-                 * Thread creation: For how long have there been zero
-                 * available threads?
-                 *
-                 * To throttle creation, we reset last_empty_jifs.
-                 */
-                if (time_after(jiffies, last_empty_jifs + 1 * HZ)) {
-                        if (list_empty(&pdflush_list)) {
-                                if (nr_pdflush_threads < MAX_PDFLUSH_THREADS) {
-                                        last_empty_jifs = jiffies;
-                                        nr_pdflush_threads++;
-                                        spin_unlock_irq(&pdflush_lock);
-                                        start_one_pdflush_thread();
-                                        spin_lock_irq(&pdflush_lock);
-                                }
-                        }
-                }
-
-                my_work->fn = NULL;
-
-                /*
-                 * Thread destruction: For how long has the sleepiest
-                 * thread slept?
-                 */
-                if (list_empty(&pdflush_list))
-                        continue;
-                if (nr_pdflush_threads <= MIN_PDFLUSH_THREADS)
-                        continue;
-                pdf = list_entry(pdflush_list.prev, struct pdflush_work, list);
-                if (time_after(jiffies, pdf->when_i_went_to_sleep + 1 * HZ)) {
-                        /* Limit exit rate */
-                        pdf->when_i_went_to_sleep = jiffies;
-                        break;                                  /* exeunt */
-                }
-        }
-        nr_pdflush_threads--;
-        spin_unlock_irq(&pdflush_lock);
-        return 0;
-}
-
-/*
- * Of course, my_work wants to be just a local in __pdflush().  It is
- * separated out in this manner to hopefully prevent the compiler from
- * performing unfortunate optimisations against the auto variables.  Because
- * these are visible to other tasks and CPUs.  (No problem has actually
- * been observed.  This is just paranoia).
- */
-static int pdflush(void *dummy)
-{
-        struct pdflush_work my_work;
-        cpumask_var_t cpus_allowed;
-
-        /*
-         * Since the caller doesn't even check kthread_run() worked, let's not
-         * freak out too much if this fails.
-         */
-        if (!alloc_cpumask_var(&cpus_allowed, GFP_KERNEL)) {
-                printk(KERN_WARNING "pdflush failed to allocate cpumask\n");
-                return 0;
-        }
-
-        /*
-         * pdflush can spend a lot of time doing encryption via dm-crypt.  We
-         * don't want to do that at keventd's priority.
-         */
-        set_user_nice(current, 0);
-
-        /*
-         * Some configs put our parent kthread in a limited cpuset,
-         * which kthread() overrides, forcing cpus_allowed == cpu_all_mask.
-         * Our needs are more modest - cut back to our cpusets cpus_allowed.
-         * This is needed as pdflush's are dynamically created and destroyed.
-         * The boottime pdflush's are easily placed w/o these 2 lines.
-         */
-        cpuset_cpus_allowed(current, cpus_allowed);
-        set_cpus_allowed_ptr(current, cpus_allowed);
-        free_cpumask_var(cpus_allowed);
-
-        return __pdflush(&my_work);
-}
-
-/*
- * Attempt to wake up a pdflush thread, and get it to do some work for you.
- * Returns zero if it indeed managed to find a worker thread, and passed your
- * payload to it.
- */
-int pdflush_operation(void (*fn)(unsigned long), unsigned long arg0)
-{
-        unsigned long flags;
-        int ret = 0;
-
-        BUG_ON(fn == NULL);     /* Hard to diagnose if it's deferred */
-
-        spin_lock_irqsave(&pdflush_lock, flags);
-        if (list_empty(&pdflush_list)) {
-                ret = -1;
-        } else {
-                struct pdflush_work *pdf;
-
-                pdf = list_entry(pdflush_list.next, struct pdflush_work, list);
-                list_del_init(&pdf->list);
-                if (list_empty(&pdflush_list))
-                        last_empty_jifs = jiffies;
-                pdf->fn = fn;
-                pdf->arg0 = arg0;
-                wake_up_process(pdf->who);
-        }
-        spin_unlock_irqrestore(&pdflush_lock, flags);
-
-        return ret;
-}
-
-static void start_one_pdflush_thread(void)
-{
-        struct task_struct *k;
-
-        k = kthread_run(pdflush, NULL, "pdflush");
-        if (unlikely(IS_ERR(k))) {
-                spin_lock_irq(&pdflush_lock);
-                nr_pdflush_threads--;
-                spin_unlock_irq(&pdflush_lock);
-        }
-}
-
-static int __init pdflush_init(void)
-{
-        int i;
-
-        /*
-         * Pre-set nr_pdflush_threads...  If we fail to create,
-         * the count will be decremented.
-         */
-        nr_pdflush_threads = MIN_PDFLUSH_THREADS;
-
-        for (i = 0; i < MIN_PDFLUSH_THREADS; i++)
-                start_one_pdflush_thread();
-        return 0;
-}
-
-module_init(pdflush_init);
diff --git a/mm/swap_state.c b/mm/swap_state.c
index 42cd38eba79f..5ae6b8b78c80 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -34,6 +34,7 @@ static const struct address_space_operations swap_aops = {
 };
 
 static struct backing_dev_info swap_backing_dev_info = {
+        .name           = "swap",
         .capabilities   = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
         .unplug_io_fn   = swap_unplug_io_fn,
 };
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 94e86dd6954c..ba8228e0a806 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1720,7 +1720,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
                  */
                 if (total_scanned > sc->swap_cluster_max +
                                         sc->swap_cluster_max / 2) {
-                        wakeup_pdflush(laptop_mode ? 0 : total_scanned);
+                        wakeup_flusher_threads(laptop_mode ? 0 : total_scanned);
                         sc->may_writepage = 1;
                 }