Btrfs: fix misuse of trans block rsv

At the beginning of create_pending_snapshot, trans->block_rsv is set
to pending->block_rsv and is used for snapshot things, however, when
it is done, we do not recover it as will.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 7dc36fab4afc5b9df1c4655e455c8df8bd3ee39b..e24b7964a15502b2ff0f6325f4a2b98c226b6688 100644 (file)
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -884,6 +884,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
        struct btrfs_root *tree_root = fs_info->tree_root;
        struct btrfs_root *root = pending->root;
        struct btrfs_root *parent_root;
+       struct btrfs_block_rsv *rsv;
        struct inode *parent_inode;
        struct dentry *parent;
        struct dentry *dentry;
@@ -895,6 +896,8 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
        u64 objectid;
        u64 root_flags;
 
+       rsv = trans->block_rsv;
+
        new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
        if (!new_root_item) {
                pending->error = -ENOMEM;
@@ -1002,6 +1005,7 @@ static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
        btrfs_orphan_post_snapshot(trans, pending);
 fail:
        kfree(new_root_item);
+       trans->block_rsv = rsv;
        btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
        return 0;
 }