1 files changed, 37 insertions, 18 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 82b03afcbd92..1791c6e3d834 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -56,48 +56,49 @@ static noinline void switch_commit_root(struct btrfs_root *root)
 static noinline int join_transaction(struct btrfs_root *root, int nofail)
 {
         struct btrfs_transaction *cur_trans;
+        struct btrfs_fs_info *fs_info = root->fs_info;
 
-        spin_lock(&root->fs_info->trans_lock);
+        spin_lock(&fs_info->trans_lock);
 loop:
         /* The file system has been taken offline. No new transactions. */
-        if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
-                spin_unlock(&root->fs_info->trans_lock);
+        if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
+                spin_unlock(&fs_info->trans_lock);
                 return -EROFS;
         }
 
-        if (root->fs_info->trans_no_join) {
+        if (fs_info->trans_no_join) {
                 if (!nofail) {
-                        spin_unlock(&root->fs_info->trans_lock);
+                        spin_unlock(&fs_info->trans_lock);
                         return -EBUSY;
                 }
         }
 
-        cur_trans = root->fs_info->running_transaction;
+        cur_trans = fs_info->running_transaction;
         if (cur_trans) {
                 if (cur_trans->aborted) {
-                        spin_unlock(&root->fs_info->trans_lock);
+                        spin_unlock(&fs_info->trans_lock);
                         return cur_trans->aborted;
                 }
                 atomic_inc(&cur_trans->use_count);
                 atomic_inc(&cur_trans->num_writers);
                 cur_trans->num_joined++;
-                spin_unlock(&root->fs_info->trans_lock);
+                spin_unlock(&fs_info->trans_lock);
                 return 0;
         }
-        spin_unlock(&root->fs_info->trans_lock);
+        spin_unlock(&fs_info->trans_lock);
 
         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
         if (!cur_trans)
                 return -ENOMEM;
 
-        spin_lock(&root->fs_info->trans_lock);
-        if (root->fs_info->running_transaction) {
+        spin_lock(&fs_info->trans_lock);
+        if (fs_info->running_transaction) {
                 /*
                  * someone started a transaction after we unlocked.  Make sure
                  * to redo the trans_no_join checks above
                  */
                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
-                cur_trans = root->fs_info->running_transaction;
+                cur_trans = fs_info->running_transaction;
                 goto loop;
         }
 
@@ -122,20 +123,38 @@ loop:
         cur_trans->delayed_refs.flushing = 0;
         cur_trans->delayed_refs.run_delayed_start = 0;
         cur_trans->delayed_refs.seq = 1;
+
+        /*
+         * although the tree mod log is per file system and not per transaction,
+         * the log must never go across transaction boundaries.
+         */
+        smp_mb();
+        if (!list_empty(&fs_info->tree_mod_seq_list)) {
+                printk(KERN_ERR "btrfs: tree_mod_seq_list not empty when "
+                        "creating a fresh transaction\n");
+                WARN_ON(1);
+        }
+        if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log)) {
+                printk(KERN_ERR "btrfs: tree_mod_log rb tree not empty when "
+                        "creating a fresh transaction\n");
+                WARN_ON(1);
+        }
+        atomic_set(&fs_info->tree_mod_seq, 0);
+
         init_waitqueue_head(&cur_trans->delayed_refs.seq_wait);
         spin_lock_init(&cur_trans->commit_lock);
         spin_lock_init(&cur_trans->delayed_refs.lock);
         INIT_LIST_HEAD(&cur_trans->delayed_refs.seq_head);
 
         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
-        list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
+        list_add_tail(&cur_trans->list, &fs_info->trans_list);
         extent_io_tree_init(&cur_trans->dirty_pages,
-                             root->fs_info->btree_inode->i_mapping);
-        root->fs_info->generation++;
-        cur_trans->transid = root->fs_info->generation;
-        root->fs_info->running_transaction = cur_trans;
+                             fs_info->btree_inode->i_mapping);
+        fs_info->generation++;
+        cur_trans->transid = fs_info->generation;
+        fs_info->running_transaction = cur_trans;
         cur_trans->aborted = 0;
-        spin_unlock(&root->fs_info->trans_lock);
+        spin_unlock(&fs_info->trans_lock);
 
         return 0;
 }