Re: [PATH]Fix cow semantic in run_delalloc_nocow()

["Yan Zheng" <yanzheng@21cn.com>]

2008/11/20 Liu Hui <onlyflyer@gmail.com>:
> Hi,
> I found cow doesn't behave as expected in run_delalloc_nocow(). Now in
> run_delalloc_now(), if it found a regular extent and the NODATACOW is
> set, run_dealloc_now will cow the file range which is not as expected.
> Also, if it find a regular extent and NODATACOW is not set(with
> PREALLOC set), it will not take cow operation. So, the cow semantic is
> opposite to the btrfs design.
>
> I found the problem was introduced by fallocate(), so could Yan please
> verify the fix? Much appreciated!
>
> --
> Thanks & Best Regards
> Liu Hui
> --
>
> diff --git a/inode.c b/inode.c
> index 2c77e09..5525594 100644
> --- a/inode.c
> +++ b/inode.c
> @@ -1003,7 +1003,7 @@ next_slot:
>                                goto out_check;
>                        if (disk_bytenr == 0)
>                                goto out_check;
> -                       if (extent_type == BTRFS_FILE_EXTENT_REG && !force)
> +                       if (extent_type == BTRFS_FILE_EXTENT_REG && force)
>                                goto out_check;
>                        if (btrfs_cross_ref_exist(trans, root, disk_bytenr))
>                                goto out_check;
> --

You are right, thanks. I suggest modifying run_delalloc_range instead of here,
could you please send a new patch.

Yan Zheng