Btrfs: Fix race in running_transaction checks
When a new transaction was started, the code would incorrectly
set the pointer in fs_info before all the data structures were setup.
fsync heavy workloads hit races on the setup of the ordered inode spinlock
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 57746c1..1cb084e 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -56,7 +56,6 @@
total_trans++;
BUG_ON(!cur_trans);
root->fs_info->generation++;
- root->fs_info->running_transaction = cur_trans;
root->fs_info->last_alloc = 0;
root->fs_info->last_data_alloc = 0;
cur_trans->num_writers = 1;
@@ -74,6 +73,9 @@
extent_io_tree_init(&cur_trans->dirty_pages,
root->fs_info->btree_inode->i_mapping,
GFP_NOFS);
+ spin_lock(&root->fs_info->new_trans_lock);
+ root->fs_info->running_transaction = cur_trans;
+ spin_unlock(&root->fs_info->new_trans_lock);
} else {
cur_trans->num_writers++;
cur_trans->num_joined++;
