3 files changed, 49 insertions, 286 deletions

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 41733c5dc820..502517492258 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -31,13 +31,14 @@ EXPORT_SYMBOL_GPL(noop_backing_dev_info);
 static struct class *bdi_class;
 
 /*
- * bdi_lock protects updates to bdi_list and bdi_pending_list, as well as
- * reader side protection for bdi_pending_list. bdi_list has RCU reader side
+ * bdi_lock protects updates to bdi_list. bdi_list has RCU reader side
  * locking.
  */
 DEFINE_SPINLOCK(bdi_lock);
 LIST_HEAD(bdi_list);
-LIST_HEAD(bdi_pending_list);
+
+/* bdi_wq serves all asynchronous writeback tasks */
+struct workqueue_struct *bdi_wq;
 
 void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2)
 {
@@ -257,6 +258,11 @@ static int __init default_bdi_init(void)
 {
         int err;
 
+        bdi_wq = alloc_workqueue("writeback", WQ_MEM_RECLAIM | WQ_FREEZABLE |
+                                              WQ_UNBOUND | WQ_SYSFS, 0);
+        if (!bdi_wq)
+                return -ENOMEM;
+
         err = bdi_init(&default_backing_dev_info);
         if (!err)
                 bdi_register(&default_backing_dev_info, NULL, "default");
@@ -271,26 +277,6 @@ int bdi_has_dirty_io(struct backing_dev_info *bdi)
         return wb_has_dirty_io(&bdi->wb);
 }
 
-static void wakeup_timer_fn(unsigned long data)
-{
-        struct backing_dev_info *bdi = (struct backing_dev_info *)data;
-
-        spin_lock_bh(&bdi->wb_lock);
-        if (bdi->wb.task) {
-                trace_writeback_wake_thread(bdi);
-                wake_up_process(bdi->wb.task);
-        } else if (bdi->dev) {
-                /*
-                 * When bdi tasks are inactive for long time, they are killed.
-                 * In this case we have to wake-up the forker thread which
-                 * should create and run the bdi thread.
-                 */
-                trace_writeback_wake_forker_thread(bdi);
-                wake_up_process(default_backing_dev_info.wb.task);
-        }
-        spin_unlock_bh(&bdi->wb_lock);
-}
-
 /*
  * This function is used when the first inode for this bdi is marked dirty. It
  * wakes-up the corresponding bdi thread which should then take care of the
@@ -307,176 +293,7 @@ void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi)
         unsigned long timeout;
 
         timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
-        mod_timer(&bdi->wb.wakeup_timer, jiffies + timeout);
-}
-
-/*
- * Calculate the longest interval (jiffies) bdi threads are allowed to be
- * inactive.
- */
-static unsigned long bdi_longest_inactive(void)
-{
-        unsigned long interval;
-
-        interval = msecs_to_jiffies(dirty_writeback_interval * 10);
-        return max(5UL * 60 * HZ, interval);
-}
-
-/*
- * Clear pending bit and wakeup anybody waiting for flusher thread creation or
- * shutdown
- */
-static void bdi_clear_pending(struct backing_dev_info *bdi)
-{
-        clear_bit(BDI_pending, &bdi->state);
-        smp_mb__after_clear_bit();
-        wake_up_bit(&bdi->state, BDI_pending);
-}
-
-static int bdi_forker_thread(void *ptr)
-{
-        struct bdi_writeback *me = ptr;
-
-        current->flags |= PF_SWAPWRITE;
-        set_freezable();
-
-        /*
-         * Our parent may run at a different priority, just set us to normal
-         */
-        set_user_nice(current, 0);
-
-        for (;;) {
-                struct task_struct *task = NULL;
-                struct backing_dev_info *bdi;
-                enum {
-                        NO_ACTION,   /* Nothing to do */
-                        FORK_THREAD, /* Fork bdi thread */
-                        KILL_THREAD, /* Kill inactive bdi thread */
-                } action = NO_ACTION;
-
-                /*
-                 * 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)) {
-                        del_timer(&me->wakeup_timer);
-                        wb_do_writeback(me, 0);
-                }
-
-                spin_lock_bh(&bdi_lock);
-                /*
-                 * In the following loop we are going to check whether we have
-                 * some work to do without any synchronization with tasks
-                 * waking us up to do work for them. Set the task state here
-                 * so that we don't miss wakeups after verifying conditions.
-                 */
-                set_current_state(TASK_INTERRUPTIBLE);
-
-                list_for_each_entry(bdi, &bdi_list, bdi_list) {
-                        bool have_dirty_io;
-
-                        if (!bdi_cap_writeback_dirty(bdi) ||
-                             bdi_cap_flush_forker(bdi))
-                                continue;
-
-                        WARN(!test_bit(BDI_registered, &bdi->state),
-                             "bdi %p/%s is not registered!\n", bdi, bdi->name);
-
-                        have_dirty_io = !list_empty(&bdi->work_list) ||
-                                        wb_has_dirty_io(&bdi->wb);
-
-                        /*
-                         * If the bdi has work to do, but the thread does not
-                         * exist - create it.
-                         */
-                        if (!bdi->wb.task && have_dirty_io) {
-                                /*
-                                 * Set the pending bit - if someone will try to
-                                 * unregister this bdi - it'll wait on this bit.
-                                 */
-                                set_bit(BDI_pending, &bdi->state);
-                                action = FORK_THREAD;
-                                break;
-                        }
-
-                        spin_lock(&bdi->wb_lock);
-
-                        /*
-                         * If there is no work to do and the bdi thread was
-                         * inactive long enough - kill it. The wb_lock is taken
-                         * to make sure no-one adds more work to this bdi and
-                         * wakes the bdi thread up.
-                         */
-                        if (bdi->wb.task && !have_dirty_io &&
-                            time_after(jiffies, bdi->wb.last_active +
-                                                bdi_longest_inactive())) {
-                                task = bdi->wb.task;
-                                bdi->wb.task = NULL;
-                                spin_unlock(&bdi->wb_lock);
-                                set_bit(BDI_pending, &bdi->state);
-                                action = KILL_THREAD;
-                                break;
-                        }
-                        spin_unlock(&bdi->wb_lock);
-                }
-                spin_unlock_bh(&bdi_lock);
-
-                /* Keep working if default bdi still has things to do */
-                if (!list_empty(&me->bdi->work_list))
-                        __set_current_state(TASK_RUNNING);
-
-                switch (action) {
-                case FORK_THREAD:
-                        __set_current_state(TASK_RUNNING);
-                        task = kthread_create(bdi_writeback_thread, &bdi->wb,
-                                              "flush-%s", dev_name(bdi->dev));
-                        if (IS_ERR(task)) {
-                                /*
-                                 * If thread creation fails, force writeout of
-                                 * the bdi from the thread. Hopefully 1024 is
-                                 * large enough for efficient IO.
-                                 */
-                                writeback_inodes_wb(&bdi->wb, 1024,
-                                                    WB_REASON_FORKER_THREAD);
-                        } else {
-                                /*
-                                 * The spinlock makes sure we do not lose
-                                 * wake-ups when racing with 'bdi_queue_work()'.
-                                 * And as soon as the bdi thread is visible, we
-                                 * can start it.
-                                 */
-                                spin_lock_bh(&bdi->wb_lock);
-                                bdi->wb.task = task;
-                                spin_unlock_bh(&bdi->wb_lock);
-                                wake_up_process(task);
-                        }
-                        bdi_clear_pending(bdi);
-                        break;
-
-                case KILL_THREAD:
-                        __set_current_state(TASK_RUNNING);
-                        kthread_stop(task);
-                        bdi_clear_pending(bdi);
-                        break;
-
-                case NO_ACTION:
-                        if (!wb_has_dirty_io(me) || !dirty_writeback_interval)
-                                /*
-                                 * There are no dirty data. The only thing we
-                                 * should now care about is checking for
-                                 * inactive bdi threads and killing them. Thus,
-                                 * let's sleep for longer time, save energy and
-                                 * be friendly for battery-driven devices.
-                                 */
-                                schedule_timeout(bdi_longest_inactive());
-                        else
-                                schedule_timeout(msecs_to_jiffies(dirty_writeback_interval * 10));
-                        try_to_freeze();
-                        break;
-                }
-        }
-
-        return 0;
+        mod_delayed_work(bdi_wq, &bdi->wb.dwork, timeout);
 }
 
 /*
@@ -489,6 +306,9 @@ static void bdi_remove_from_list(struct backing_dev_info *bdi)
         spin_unlock_bh(&bdi_lock);
 
         synchronize_rcu_expedited();
+
+        /* bdi_list is now unused, clear it to mark @bdi dying */
+        INIT_LIST_HEAD(&bdi->bdi_list);
 }
 
 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
@@ -508,20 +328,6 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent,
 
         bdi->dev = 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_thread, wb, "bdi-%s",
-                                                dev_name(dev));
-                if (IS_ERR(wb->task))
-                        return PTR_ERR(wb->task);
-        }
-
         bdi_debug_register(bdi, dev_name(dev));
         set_bit(BDI_registered, &bdi->state);
 
@@ -545,8 +351,6 @@ EXPORT_SYMBOL(bdi_register_dev);
  */
 static void bdi_wb_shutdown(struct backing_dev_info *bdi)
 {
-        struct task_struct *task;
-
         if (!bdi_cap_writeback_dirty(bdi))
                 return;
 
@@ -556,22 +360,20 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
         bdi_remove_from_list(bdi);
 
         /*
-         * If setup is pending, wait for that to complete first
+         * Drain work list and shutdown the delayed_work.  At this point,
+         * @bdi->bdi_list is empty telling bdi_Writeback_workfn() that @bdi
+         * is dying and its work_list needs to be drained no matter what.
          */
-        wait_on_bit(&bdi->state, BDI_pending, bdi_sched_wait,
-                        TASK_UNINTERRUPTIBLE);
+        mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
+        flush_delayed_work(&bdi->wb.dwork);
+        WARN_ON(!list_empty(&bdi->work_list));
 
         /*
-         * Finally, kill the kernel thread. We don't need to be RCU
-         * safe anymore, since the bdi is gone from visibility.
+         * This shouldn't be necessary unless @bdi for some reason has
+         * unflushed dirty IO after work_list is drained.  Do it anyway
+         * just in case.
          */
-        spin_lock_bh(&bdi->wb_lock);
-        task = bdi->wb.task;
-        bdi->wb.task = NULL;
-        spin_unlock_bh(&bdi->wb_lock);
-
-        if (task)
-                kthread_stop(task);
+        cancel_delayed_work_sync(&bdi->wb.dwork);
 }
 
 /*
@@ -597,10 +399,8 @@ void bdi_unregister(struct backing_dev_info *bdi)
                 bdi_set_min_ratio(bdi, 0);
                 trace_writeback_bdi_unregister(bdi);
                 bdi_prune_sb(bdi);
-                del_timer_sync(&bdi->wb.wakeup_timer);
 
-                if (!bdi_cap_flush_forker(bdi))
-                        bdi_wb_shutdown(bdi);
+                bdi_wb_shutdown(bdi);
                 bdi_debug_unregister(bdi);
 
                 spin_lock_bh(&bdi->wb_lock);
@@ -622,7 +422,7 @@ static void bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
         INIT_LIST_HEAD(&wb->b_io);
         INIT_LIST_HEAD(&wb->b_more_io);
         spin_lock_init(&wb->list_lock);
-        setup_timer(&wb->wakeup_timer, wakeup_timer_fn, (unsigned long)bdi);
+        INIT_DELAYED_WORK(&wb->dwork, bdi_writeback_workfn);
 }
 
 /*
@@ -695,12 +495,11 @@ void bdi_destroy(struct backing_dev_info *bdi)
         bdi_unregister(bdi);
 
         /*
-         * If bdi_unregister() had already been called earlier, the
-         * wakeup_timer could still be armed because bdi_prune_sb()
-         * can race with the bdi_wakeup_thread_delayed() calls from
-         * __mark_inode_dirty().
+         * If bdi_unregister() had already been called earlier, the dwork
+         * could still be pending because bdi_prune_sb() can race with the
+         * bdi_wakeup_thread_delayed() calls from __mark_inode_dirty().
          */
-        del_timer_sync(&bdi->wb.wakeup_timer);
+        cancel_delayed_work_sync(&bdi->wb.dwork);
 
         for (i = 0; i < NR_BDI_STAT_ITEMS; i++)
                 percpu_counter_destroy(&bdi->bdi_stat[i]);
diff --git a/mm/bounce.c b/mm/bounce.c
index a5c2ec3589cb..c9f0a4339a7d 100644
--- a/mm/bounce.c
+++ b/mm/bounce.c
@@ -101,7 +101,7 @@ static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
         struct bio_vec *tovec, *fromvec;
         int i;
 
-        __bio_for_each_segment(tovec, to, i, 0) {
+        bio_for_each_segment(tovec, to, i) {
                 fromvec = from->bi_io_vec + i;
 
                 /*
@@ -134,7 +134,7 @@ static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
         /*
          * free up bounce indirect pages used
          */
-        __bio_for_each_segment(bvec, bio, i, 0) {
+        bio_for_each_segment_all(bvec, bio, i) {
                 org_vec = bio_orig->bi_io_vec + i;
                 if (bvec->bv_page == org_vec->bv_page)
                         continue;
@@ -199,78 +199,43 @@ static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio)
 static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
                                mempool_t *pool, int force)
 {
-        struct page *page;
-        struct bio *bio = NULL;
-        int i, rw = bio_data_dir(*bio_orig);
+        struct bio *bio;
+        int rw = bio_data_dir(*bio_orig);
         struct bio_vec *to, *from;
+        unsigned i;
 
-        bio_for_each_segment(from, *bio_orig, i) {
-                page = from->bv_page;
+        bio_for_each_segment(from, *bio_orig, i)
+                if (page_to_pfn(from->bv_page) > queue_bounce_pfn(q))
+                        goto bounce;
 
-                /*
-                 * is destination page below bounce pfn?
-                 */
-                if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force)
-                        continue;
-
-                /*
-                 * irk, bounce it
-                 */
-                if (!bio) {
-                        unsigned int cnt = (*bio_orig)->bi_vcnt;
+        return;
+bounce:
+        bio = bio_clone_bioset(*bio_orig, GFP_NOIO, fs_bio_set);
 
-                        bio = bio_alloc(GFP_NOIO, cnt);
-                        memset(bio->bi_io_vec, 0, cnt * sizeof(struct bio_vec));
-                }
-                        
+        bio_for_each_segment_all(to, bio, i) {
+                struct page *page = to->bv_page;
 
-                to = bio->bi_io_vec + i;
+                if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force)
+                        continue;
 
-                to->bv_page = mempool_alloc(pool, q->bounce_gfp);
-                to->bv_len = from->bv_len;
-                to->bv_offset = from->bv_offset;
                 inc_zone_page_state(to->bv_page, NR_BOUNCE);
+                to->bv_page = mempool_alloc(pool, q->bounce_gfp);
 
                 if (rw == WRITE) {
                         char *vto, *vfrom;
 
-                        flush_dcache_page(from->bv_page);
+                        flush_dcache_page(page);
+
                         vto = page_address(to->bv_page) + to->bv_offset;
-                        vfrom = kmap(from->bv_page) + from->bv_offset;
+                        vfrom = kmap_atomic(page) + to->bv_offset;
                         memcpy(vto, vfrom, to->bv_len);
-                        kunmap(from->bv_page);
+                        kunmap_atomic(vfrom);
                 }
         }
 
-        /*
-         * no pages bounced
-         */
-        if (!bio)
-                return;
-
         trace_block_bio_bounce(q, *bio_orig);
 
-        /*
-         * at least one page was bounced, fill in possible non-highmem
-         * pages
-         */
-        __bio_for_each_segment(from, *bio_orig, i, 0) {
-                to = bio_iovec_idx(bio, i);
-                if (!to->bv_page) {
-                        to->bv_page = from->bv_page;
-                        to->bv_len = from->bv_len;
-                        to->bv_offset = from->bv_offset;
-                }
-        }
-
-        bio->bi_bdev = (*bio_orig)->bi_bdev;
         bio->bi_flags |= (1 << BIO_BOUNCED);
-        bio->bi_sector = (*bio_orig)->bi_sector;
-        bio->bi_rw = (*bio_orig)->bi_rw;
-
-        bio->bi_vcnt = (*bio_orig)->bi_vcnt;
-        bio->bi_idx = (*bio_orig)->bi_idx;
-        bio->bi_size = (*bio_orig)->bi_size;
 
         if (pool == page_pool) {
                 bio->bi_end_io = bounce_end_io_write;
diff --git a/mm/page_io.c b/mm/page_io.c
index 06a8842a6ec6..a8a3ef45fed7 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -36,7 +36,6 @@ static struct bio *get_swap_bio(gfp_t gfp_flags,
                 bio->bi_io_vec[0].bv_len = PAGE_SIZE;
                 bio->bi_io_vec[0].bv_offset = 0;
                 bio->bi_vcnt = 1;
-                bio->bi_idx = 0;
                 bio->bi_size = PAGE_SIZE;
                 bio->bi_end_io = end_io;
         }