Re: [PATCH 25/31] e2fsck: Only release clusters when shortening a directory during a rehash

Lukáš Czerner
2013-10-10T16:13:21Z

On Mon, 30 Sep 2013, Darrick J. Wong wrote:

> Date: Mon, 30 Sep 2013 18:29:21 -0700
> From: Darrick J. Wong <darrick.wong@oracle.com>
> To: tytso@mit.edu, darrick.wong@oracle.com
> Cc: linux-ext4@vger.kernel.org
> Subject: [PATCH 25/31] e2fsck: Only release clusters when shortening a
> directory during a rehash
>
> When the rehash process is running on a bigalloc filesystem, it compresses all
> the directory entries and hash structures into the beginning of the directory
> file and then uses block_iterate3() to free the blocks off the end of the file.
> It seems to call ext2fs_block_alloc_stats2() for every block in a cluster,
> which is unfortunate because this function allocates and frees entire clusters
> (and updates the summary counts accordingly). In this case e2fsck writes out
> incorrect summary counts.

Looks good.

Reviewed-by: Lukas Czerner <lczerner@redhat.com>

>
> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
> e2fsck/rehash.c | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
>
>
> diff --git a/e2fsck/rehash.c b/e2fsck/rehash.c
> index 6ef3568..29da9a1 100644
> --- a/e2fsck/rehash.c
> +++ b/e2fsck/rehash.c
> @@ -719,10 +719,18 @@ static int write_dir_block(ext2_filsys fs,
> /* We don't need this block, so release it */
> e2fsck_read_bitmaps(wd->ctx);
> blk = *block_nr;
> - ext2fs_unmark_block_bitmap2(wd->ctx->block_found_map, blk);
> - ext2fs_block_alloc_stats2(fs, blk, -1);
> + /*
> + * In theory, we only release blocks from the end of the
> + * directory file, so it's fine to clobber a whole cluster at
> + * once.
> + */
> + if (blk % EXT2FS_CLUSTER_RATIO(fs) == 0) {
> + ext2fs_unmark_block_bitmap2(wd->ctx->block_found_map,
> + blk);
> + ext2fs_block_alloc_stats2(fs, blk, -1);
> + wd->cleared++;
> + }
> *block_nr = 0;
> - wd->cleared++;
> return BLOCK_CHANGED;
> }
>
>
> --
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