Btrfs: delay commits during fsync to allow more writers

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 32 insertions, 12 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index c9d52dc83e48..18abea802794 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -55,7 +55,8 @@ static int join_transaction(struct btrfs_root *root)
                 BUG_ON(!cur_trans);
                 root->fs_info->generation++;
                 root->fs_info->running_transaction = cur_trans;
-                cur_trans->num_writers = 0;
+                cur_trans->num_writers = 1;
+                cur_trans->num_joined = 0;
                 cur_trans->transid = root->fs_info->generation;
                 init_waitqueue_head(&cur_trans->writer_wait);
                 init_waitqueue_head(&cur_trans->commit_wait);
@@ -65,8 +66,11 @@ static int join_transaction(struct btrfs_root *root)
                 cur_trans->start_time = get_seconds();
                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
                 init_bit_radix(&cur_trans->dirty_pages);
+        } else {
+                cur_trans->num_writers++;
+                cur_trans->num_joined++;
         }
-        cur_trans->num_writers++;
+
         return 0;
 }
 
@@ -428,12 +432,14 @@ static int drop_dirty_roots(struct btrfs_root *tree_root,
 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                              struct btrfs_root *root)
 {
-        int ret = 0;
+        unsigned long joined = 0;
+        unsigned long timeout = 1;
         struct btrfs_transaction *cur_trans;
         struct btrfs_transaction *prev_trans = NULL;
         struct list_head dirty_fs_roots;
         struct radix_tree_root pinned_copy;
         DEFINE_WAIT(wait);
+        int ret;
 
         init_bit_radix(&pinned_copy);
         INIT_LIST_HEAD(&dirty_fs_roots);
@@ -448,7 +454,11 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                 mutex_unlock(&root->fs_info->fs_mutex);
                 ret = wait_for_commit(root, cur_trans);
                 BUG_ON(ret);
+
+                mutex_lock(&root->fs_info->trans_mutex);
                 put_transaction(cur_trans);
+                mutex_unlock(&root->fs_info->trans_mutex);
+
                 mutex_lock(&root->fs_info->fs_mutex);
                 return 0;
         }
@@ -463,26 +473,35 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
                         mutex_unlock(&root->fs_info->trans_mutex);
 
                         wait_for_commit(root, prev_trans);
-                        put_transaction(prev_trans);
 
                         mutex_lock(&root->fs_info->fs_mutex);
                         mutex_lock(&root->fs_info->trans_mutex);
+                        put_transaction(prev_trans);
                 }
         }
-        while (trans->transaction->num_writers > 1) {
+
+        do {
+                joined = cur_trans->num_joined;
                 WARN_ON(cur_trans != trans->transaction);
-                prepare_to_wait(&trans->transaction->writer_wait, &wait,
+                prepare_to_wait(&cur_trans->writer_wait, &wait,
                                 TASK_UNINTERRUPTIBLE);
-                if (trans->transaction->num_writers <= 1)
-                        break;
+
+                if (cur_trans->num_writers > 1)
+                        timeout = MAX_SCHEDULE_TIMEOUT;
+                else
+                        timeout = 1;
+
                 mutex_unlock(&root->fs_info->fs_mutex);
                 mutex_unlock(&root->fs_info->trans_mutex);
-                schedule();
+
+                schedule_timeout(timeout);
+
                 mutex_lock(&root->fs_info->fs_mutex);
                 mutex_lock(&root->fs_info->trans_mutex);
-                finish_wait(&trans->transaction->writer_wait, &wait);
-        }
-        finish_wait(&trans->transaction->writer_wait, &wait);
+                finish_wait(&cur_trans->writer_wait, &wait);
+        } while (cur_trans->num_writers > 1 ||
+                 (cur_trans->num_joined != joined));
+
         WARN_ON(cur_trans != trans->transaction);
         ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
                               &dirty_fs_roots);
@@ -511,6 +530,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
         btrfs_finish_extent_commit(trans, root, &pinned_copy);
         mutex_lock(&root->fs_info->trans_mutex);
         cur_trans->commit_done = 1;
+        root->fs_info->last_trans_committed = cur_trans->transid;
         wake_up(&cur_trans->commit_wait);
         put_transaction(cur_trans);
         put_transaction(cur_trans);