3 files changed, 33 insertions, 20 deletions

diff --git a/fs/btrfs/async-thread.c b/fs/btrfs/async-thread.c
index 5f2f5a8c2289..958cd8b5f0d7 100644
--- a/fs/btrfs/async-thread.c
+++ b/fs/btrfs/async-thread.c
@@ -48,6 +48,7 @@ struct btrfs_worker_thread {
 
         /* number of things on the pending list */
         atomic_t num_pending;
+        unsigned long sequence;
 
         /* protects the pending list. */
         spinlock_t lock;
@@ -197,6 +198,7 @@ int btrfs_start_workers(struct btrfs_workers *workers, int num_workers)
 
                 spin_lock_irq(&workers->lock);
                 list_add_tail(&worker->worker_list, &workers->idle_list);
+                worker->idle = 1;
                 workers->num_workers++;
                 spin_unlock_irq(&workers->lock);
         }
@@ -238,7 +240,10 @@ static struct btrfs_worker_thread *next_worker(struct btrfs_workers *workers)
          */
         next = workers->worker_list.next;
         worker = list_entry(next, struct btrfs_worker_thread, worker_list);
-        list_move_tail(next, &workers->worker_list);
+        atomic_inc(&worker->num_pending);
+        worker->sequence++;
+        if (worker->sequence % 4 == 0)
+                list_move_tail(next, &workers->worker_list);
         return worker;
 }
 
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index bb4a8d2200d0..040213359393 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -526,6 +526,7 @@ struct btrfs_fs_info {
         struct btrfs_transaction *running_transaction;
         wait_queue_head_t transaction_throttle;
         wait_queue_head_t transaction_wait;
+        wait_queue_head_t async_submit_wait;
         struct btrfs_super_block super_copy;
         struct btrfs_super_block super_for_commit;
         struct block_device *__bdev;
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 1bf210dadef6..1aed1f4616b6 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -429,31 +429,36 @@ int btrfs_bio_wq_end_io(struct btrfs_fs_info *info, struct bio *bio,
         return 0;
 }
 
-int btrfs_congested_async(struct btrfs_fs_info *info, int iodone)
+static unsigned long async_submit_limit(struct btrfs_fs_info *info)
 {
-        int limit = 256 * info->fs_devices->open_devices;
-
-        if (iodone)
-                limit = (limit * 3) / 2;
-        if (atomic_read(&info->nr_async_submits) > limit)
-                return 1;
+        unsigned long limit = min_t(unsigned long,
+                                    info->workers.max_workers,
+                                    info->fs_devices->open_devices);
+        return 256 * limit;
+}
 
-        return atomic_read(&info->nr_async_bios) > limit;
+int btrfs_congested_async(struct btrfs_fs_info *info, int iodone)
+{
+        return atomic_read(&info->nr_async_bios) > async_submit_limit(info);
 }
 
 static void run_one_async_submit(struct btrfs_work *work)
 {
         struct btrfs_fs_info *fs_info;
         struct async_submit_bio *async;
+        int limit;
 
         async = container_of(work, struct  async_submit_bio, work);
         fs_info = BTRFS_I(async->inode)->root->fs_info;
+
+        limit = async_submit_limit(fs_info);
+        limit = limit * 2 / 3;
+
         atomic_dec(&fs_info->nr_async_submits);
 
-        if ((async->bio->bi_rw & (1 << BIO_RW)) &&
-            !btrfs_congested_async(fs_info, 1)) {
-                clear_bdi_congested(&fs_info->bdi, WRITE);
-        }
+        if (atomic_read(&fs_info->nr_async_submits) < limit)
+                wake_up(&fs_info->async_submit_wait);
+
         async->submit_bio_hook(async->inode, async->rw, async->bio,
                                async->mirror_num);
         kfree(async);
@@ -464,6 +469,7 @@ int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode,
                         extent_submit_bio_hook_t *submit_bio_hook)
 {
         struct async_submit_bio *async;
+        int limit = async_submit_limit(fs_info);
 
         async = kmalloc(sizeof(*async), GFP_NOFS);
         if (!async)
@@ -478,6 +484,10 @@ int btrfs_wq_submit_bio(struct btrfs_fs_info *fs_info, struct inode *inode,
         async->work.flags = 0;
         atomic_inc(&fs_info->nr_async_submits);
         btrfs_queue_worker(&fs_info->workers, &async->work);
+
+        wait_event_timeout(fs_info->async_submit_wait,
+                           (atomic_read(&fs_info->nr_async_submits) < limit),
+                           HZ/10);
         return 0;
 }
 
@@ -545,16 +555,11 @@ static int btree_writepages(struct address_space *mapping,
         if (wbc->sync_mode == WB_SYNC_NONE) {
                 u64 num_dirty;
                 u64 start = 0;
-                unsigned long thresh = 96 * 1024 * 1024;
+                unsigned long thresh = 8 * 1024 * 1024;
 
                 if (wbc->for_kupdate)
                         return 0;
 
-                if (current_is_pdflush()) {
-                        thresh = 96 * 1024 * 1024;
-                } else {
-                        thresh = 8 * 1024 * 1024;
-                }
                 num_dirty = count_range_bits(tree, &start, (u64)-1,
                                              thresh, EXTENT_DIRTY);
                 if (num_dirty < thresh) {
@@ -1333,6 +1338,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
         mutex_init(&fs_info->volume_mutex);
         init_waitqueue_head(&fs_info->transaction_throttle);
         init_waitqueue_head(&fs_info->transaction_wait);
+        init_waitqueue_head(&fs_info->async_submit_wait);
 
 #if 0
         ret = add_hasher(fs_info, "crc32c");
@@ -1380,6 +1386,7 @@ struct btrfs_root *open_ctree(struct super_block *sb,
          * devices
          */
         fs_info->submit_workers.idle_thresh = 64;
+        fs_info->workers.idle_thresh = 32;
 
         btrfs_init_workers(&fs_info->fixup_workers, "fixup", 1);
         btrfs_init_workers(&fs_info->endio_workers, "endio",
@@ -1849,7 +1856,7 @@ void btrfs_btree_balance_dirty(struct btrfs_root *root, unsigned long nr)
         struct extent_io_tree *tree;
         u64 num_dirty;
         u64 start = 0;
-        unsigned long thresh = 2 * 1024 * 1024;
+        unsigned long thresh = 12 * 1024 * 1024;
         tree = &BTRFS_I(root->fs_info->btree_inode)->io_tree;
 
         if (current_is_pdflush())