Btrfs: early fsync support

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

1 files changed, 22 insertions, 3 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 8740752f3845..078cb9cbf9dd 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -19,6 +19,7 @@ static void put_transaction(struct btrfs_transaction *transaction)
         if (transaction->use_count == 0) {
                 WARN_ON(total_trans == 0);
                 total_trans--;
+                list_del_init(&transaction->list);
                 memset(transaction, 0, sizeof(*transaction));
                 kmem_cache_free(btrfs_transaction_cachep, transaction);
         }
@@ -43,6 +44,7 @@ static int join_transaction(struct btrfs_root *root)
                 cur_trans->in_commit = 0;
                 cur_trans->use_count = 1;
                 cur_trans->commit_done = 0;
+                list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
         }
         cur_trans->num_writers++;
         return 0;
@@ -236,6 +238,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 {
         int ret = 0;
         struct btrfs_transaction *cur_trans;
+        struct btrfs_transaction *prev_trans = NULL;
         struct list_head dirty_fs_roots;
         DEFINE_WAIT(wait);
 
@@ -272,13 +275,29 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
         BUG_ON(ret);
         cur_trans = root->fs_info->running_transaction;
         root->fs_info->running_transaction = NULL;
-        btrfs_set_super_generation(root->fs_info->disk_super,
-                                   root->fs_info->generation + 1);
+        if (cur_trans->list.prev != &root->fs_info->trans_list) {
+                prev_trans = list_entry(cur_trans->list.prev,
+                                        struct btrfs_transaction, list);
+                if (prev_trans->commit_done)
+                        prev_trans = NULL;
+                else
+                        prev_trans->use_count++;
+        }
         mutex_unlock(&root->fs_info->trans_mutex);
+        mutex_unlock(&root->fs_info->fs_mutex);
         ret = btrfs_write_and_wait_transaction(trans, root);
+        if (prev_trans) {
+                mutex_lock(&root->fs_info->trans_mutex);
+                wait_for_commit(root, prev_trans);
+                put_transaction(prev_trans);
+                mutex_unlock(&root->fs_info->trans_mutex);
+        }
+        btrfs_set_super_generation(root->fs_info->disk_super,
+                                   cur_trans->transid);
         BUG_ON(ret);
-
         write_ctree_super(trans, root);
+
+        mutex_lock(&root->fs_info->fs_mutex);
         btrfs_finish_extent_commit(trans, root);
         mutex_lock(&root->fs_info->trans_mutex);
         cur_trans->commit_done = 1;