linux-ext4 - Re: [PATCH 47/74] resize2fs: during shrink, don't free in-use bg data clusters

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Date:	Mon, 16 Dec 2013 00:01:47 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	"Darrick J. Wong" <darrick.wong@...cle.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: [PATCH 47/74] resize2fs: during shrink, don't free in-use bg
 data clusters

On Tue, Dec 10, 2013 at 05:23:33PM -0800, Darrick J. Wong wrote:
> When freeing a group's metadata blocks, be careful not to free
> clusters belonging to other groups!
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
> ---
>  resize/resize2fs.c |   78 +++++++++++++++++++++++++++++++++-------------------
>  1 file changed, 49 insertions(+), 29 deletions(-)
> 
> 
> diff --git a/resize/resize2fs.c b/resize/resize2fs.c
> index ff5e6a2..49fe986 100644
> --- a/resize/resize2fs.c
> +++ b/resize/resize2fs.c
> @@ -270,40 +270,60 @@ static void fix_uninit_block_bitmaps(ext2_filsys fs)
>   * release them in the new filesystem data structure, and mark them as
>   * reserved so the old inode table blocks don't get overwritten.
>   */
> -static void free_gdp_blocks(ext2_filsys fs,
> -			    ext2fs_block_bitmap reserve_blocks,
> -			    ext2_filsys old_fs,
> -			    dgrp_t group)
> +static errcode_t free_gdp_blocks(ext2_filsys fs,
> +				 ext2fs_block_bitmap reserve_blocks,
> +				 ext2_filsys old_fs,
> +				 dgrp_t group, dgrp_t count)

This function is only used in one place, and "count" is calculated
using values from fs and old_fs.

	old_fs->group_desc_count - fs->group_desc_count

Wouldn't it be clearer to do this calculation in free_gdp_blocks, i.e:

	dgrp_t count = old_fs->group_desc_count - fs->group_desc_count;

This makes it clearer what's going on, instead of using a generic
parameter name such as "count" which isn't as clear...

	       	       	       	     - Ted
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