From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Dongyang Li <dongyangli@ddn.com>
Cc: "linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>,
"adilger@dilger.ca" <adilger@dilger.ca>
Subject: Re: [PATCH 2/2] mke2fs: set overhead in super block for bigalloc
Date: Mon, 19 Aug 2019 01:09:17 -0400 [thread overview]
Message-ID: <20190819050917.GD10349@mit.edu> (raw)
In-Reply-To: <20190816034834.29439-2-dongyangli@ddn.com>
On Fri, Aug 16, 2019 at 03:49:14AM +0000, Dongyang Li wrote:
> Fix a bug in handle_bad_blocks(), don't covert the bad block to
> cluster when marking it as used, the bitmap is still a block bitmap,
> will be coverted to cluster bitmap later.
Please separate the bug fix into a separate commit.
> Note: in kernel the overhead is the s_overhead_clusters field from
> struct ext4_super_block, it's named s_overhead_blocks in e2fsprogs
Please fix up the field name in e2fsprogs, again in a separate commit.
> +errcode_t ext2fs_convert_subcluster_bitmap_overhead(ext2_filsys fs,
> + ext2fs_block_bitmap *bitmap,
> + badblocks_list bb_list,
> + unsigned int *count);
So I really hate this abstraction which you've proposed. It's very
mke2fs specific, and mixing the bb_list abstraction into bitmap is
just really ugly.
Instead let me suggest the following:
1) Have mke2fs unset the blocks in bb_list from the block bitmap.
2) Then have mke2fs call ext2fs_convert_subcluster_bitmap()
3) Create an abstraction which counts the number of clusters in the
bitmap, by using find_first_set() and first_first_zero().
4) Let mke2fs call that function defined in (3) above on the
converted cluster bitmap() to get the overhead in clusters
5) Iterate over the bb_list to set the clusters in the converted
cluster-granularity allocation map.
The abstraction in (3) is much less mke2fs specific, and if you make
the abstraction take a starting and ending block count, there are
potentially other use cases (for example, counting the number of
clusters in use in a block group).
Cheers,
- Ted
next prev parent reply other threads:[~2019-08-19 5:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-16 3:49 [PATCH 1/2] libext2fs: optimize ext2fs_convert_subcluster_bitmap() Dongyang Li
2019-08-16 3:49 ` [PATCH 2/2] mke2fs: set overhead in super block for bigalloc Dongyang Li
2019-08-16 7:01 ` Andreas Dilger
2019-08-19 5:09 ` Theodore Y. Ts'o [this message]
2019-08-16 5:58 ` [PATCH 1/2] libext2fs: optimize ext2fs_convert_subcluster_bitmap() Andreas Dilger
2019-08-19 4:39 ` Theodore Y. Ts'o
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