Btrfs: use atomic for fs_info->last_trans_committed

index c3edb22..34a60a8 100644
@@ -1279,7 +1279,7 @@ struct btrfs_fs_info {
 	struct btrfs_block_rsv empty_block_rsv;
 
 	atomic64_t generation;
-	u64 last_trans_committed;
+	atomic64_t last_trans_committed;
 
 	/*
 	 * this is updated to the current trans every time a full commit

index 2d69541..9263c6e 100644
@@ -2502,7 +2502,7 @@ retry_root_backup:
 	}
 
 	atomic64_set(&fs_info->generation, generation);
-	fs_info->last_trans_committed = generation;
+	atomic64_set(&fs_info->last_trans_committed, generation);
 
 	ret = btrfs_recover_balance(fs_info);
 	if (ret) {

index 024246b..3e9fa0e 100644
@@ -1683,7 +1683,7 @@ int btrfs_sync_file(struct file *file, loff_t start, loff_t end, int datasync)
 	if (btrfs_inode_in_log(inode,
 	    atomic64_read(&root->fs_info->generation)) ||
 	    BTRFS_I(inode)->last_trans <=
-	    root->fs_info->last_trans_committed) {
+	    atomic64_read(&root->fs_info->last_trans_committed)) {
 		BTRFS_I(inode)->last_trans = 0;
 
 		/*

index 7624212..804c57f 100644
@@ -3110,7 +3110,7 @@ static noinline long btrfs_ioctl_start_sync(struct btrfs_root *root,
 			return PTR_ERR(trans);
 
 		/* No running transaction, don't bother */
-		transid = root->fs_info->last_trans_committed;
+		transid = atomic64_read(&root->fs_info->last_trans_committed);
 		goto out;
 	}
 	transid = trans->transid;

index f107312..f376621 100644
@@ -975,7 +975,7 @@ void btrfs_add_ordered_operation(struct btrfs_trans_handle *trans,
 	 * if this file hasn't been changed since the last transaction
 	 * commit, we can safely return without doing anything
 	 */
-	if (last_mod < root->fs_info->last_trans_committed)
+	if (last_mod < atomic64_read(&root->fs_info->last_trans_committed))
 		return;
 
 	spin_lock(&root->fs_info->ordered_extent_lock);

index bdbb94f..af0b566 100644
@@ -2703,7 +2703,7 @@ static noinline_for_stack int scrub_supers(struct scrub_ctx *sctx,
 	if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 		return -EIO;
 
-	gen = root->fs_info->last_trans_committed;
+	gen = atomic64_read(&root->fs_info->last_trans_committed);
 
 	for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
 		bytenr = btrfs_sb_offset(i);

index e7992ca..7999bf8 100644
@@ -459,7 +459,8 @@ int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 	int ret = 0;
 
 	if (transid) {
-		if (transid <= root->fs_info->last_trans_committed)
+		if (transid <=
+		    atomic64_read(&root->fs_info->last_trans_committed))
 			goto out;
 
 		ret = -EINVAL;

@@ -1713,7 +1714,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 
 	cur_trans->commit_done = 1;
 
-	root->fs_info->last_trans_committed = cur_trans->transid;
+	atomic64_set(&root->fs_info->last_trans_committed, cur_trans->transid);
 
 	wake_up(&cur_trans->commit_wait);
 

index 83186c7..e6c8eb2 100644
@@ -3392,7 +3392,7 @@ static int btrfs_log_changed_extents(struct btrfs_trans_handle *trans,
 	INIT_LIST_HEAD(&extents);
 
 	write_lock(&tree->lock);
-	test_gen = root->fs_info->last_trans_committed;
+	test_gen = atomic64_read(&root->fs_info->last_trans_committed);
 
 	list_for_each_entry_safe(em, n, &tree->modified_extents, list) {
 		list_del_init(&em->list);

@@ -3496,7 +3496,8 @@ static int btrfs_log_inode(struct btrfs_trans_handle *trans,
 
 	/* Only run delayed items if we are a dir or a new file */
 	if (S_ISDIR(inode->i_mode) ||
-	    BTRFS_I(inode)->generation > root->fs_info->last_trans_committed) {
+	    BTRFS_I(inode)->generation >
+	    atomic64_read(&root->fs_info->last_trans_committed)) {
 		ret = btrfs_commit_inode_delayed_items(trans, inode);
 		if (ret) {
 			btrfs_free_path(path);

@@ -3738,7 +3739,8 @@ int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
 	struct super_block *sb;
 	struct dentry *old_parent = NULL;
 	int ret = 0;
-	u64 last_committed = root->fs_info->last_trans_committed;
+	u64 last_committed = atomic64_read(
+			     &root->fs_info->last_trans_committed);
 
 	sb = inode->i_sb;
 

@@ -3748,7 +3750,7 @@ int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
 	}
 
 	if (root->fs_info->last_trans_log_full_commit >
-	    root->fs_info->last_trans_committed) {
+	    atomic64_read(&root->fs_info->last_trans_committed)) {
 		ret = 1;
 		goto end_no_trans;
 	}

@@ -3800,7 +3802,7 @@ int btrfs_log_inode_parent(struct btrfs_trans_handle *trans,
 			break;
 
 		if (BTRFS_I(inode)->generation >
-		    root->fs_info->last_trans_committed) {
+		    atomic64_read(&root->fs_info->last_trans_committed)) {
 			ret = btrfs_log_inode(trans, root, inode, inode_only);
 			if (ret)
 				goto end_trans;

@@ -4063,9 +4065,9 @@ int btrfs_log_new_name(struct btrfs_trans_handle *trans,
 	 * from hasn't been logged, we don't need to log it
 	 */
 	if (BTRFS_I(inode)->logged_trans <=
-	    root->fs_info->last_trans_committed &&
+	    atomic64_read(&root->fs_info->last_trans_committed) &&
 	    (!old_dir || BTRFS_I(old_dir)->logged_trans <=
-		    root->fs_info->last_trans_committed))
+		    atomic64_read(&root->fs_info->last_trans_committed)))
 		return 0;
 
 	return btrfs_log_inode_parent(trans, root, inode, parent, 1);