From: Matthew Wilcox <willy@infradead.org>
To: Gao Xiang <gaoxiang25@huawei.com>,
Dave Chinner <david@fromorbit.com>,
Goldwyn Rodrigues <RGoldwyn@suse.com>, "hch@lst.de" <hch@lst.de>,
"darrick.wong@oracle.com" <darrick.wong@oracle.com>,
"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>,
"ruansy.fnst@cn.fujitsu.com" <ruansy.fnst@cn.fujitsu.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
linux-erofs@lists.ozlabs.org, miaoxie@huawei.com
Subject: Re: [PATCH 10/13] iomap: use a function pointer for dio submits
Date: Fri, 9 Aug 2019 13:45:17 -0700 [thread overview]
Message-ID: <20190809204517.GR5482@bombadil.infradead.org> (raw)
In-Reply-To: <20190808054936.GA5319@sol.localdomain>
On Wed, Aug 07, 2019 at 10:49:36PM -0700, Eric Biggers wrote:
> On Thu, Aug 08, 2019 at 12:26:42PM +0800, Gao Xiang wrote:
> > 1. decrypt->verity->decompress
> >
> > 2. verity->decompress->decrypt
> >
> > 3. decompress->decrypt->verity
> >
> > 1. and 2. could cause less computation since it processes
> > compressed data, and the security is good enough since
> > the behavior of decompression algorithm is deterministic.
> > 3 could cause more computation.
> >
> > All I want to say is the post process is so complicated since we have
> > many selection if encryption, decompression, verification are all involved.
> >
> > Maybe introduce a core subset to IOMAP is better for long-term
> > maintainment and better performance. And we should consider it
> > more carefully.
> >
>
> FWIW, the only order that actually makes sense is decrypt->decompress->verity.
That used to be true, but a paper in 2004 suggested it's not true.
Further work in this space in 2009 based on block ciphers:
https://arxiv.org/pdf/1009.1759
It looks like it'd be computationally expensive to do, but feasible.
> Decrypt before decompress, i.e. encrypt after compress, because only the
> plaintext can be compressible; the ciphertext isn't.
next prev parent reply other threads:[~2019-08-09 20:45 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-02 22:00 [PATCH v2 0/13] Btrfs iomap Goldwyn Rodrigues
2019-08-02 22:00 ` [PATCH 01/13] iomap: Use a IOMAP_COW/srcmap for a read-modify-write I/O Goldwyn Rodrigues
2019-08-03 0:39 ` Darrick J. Wong
2019-08-05 0:06 ` Dave Chinner
2019-08-02 22:00 ` [PATCH 02/13] iomap: Read page from srcmap for IOMAP_COW Goldwyn Rodrigues
2019-08-03 0:23 ` Darrick J. Wong
2019-08-04 23:52 ` Dave Chinner
2019-08-02 22:00 ` [PATCH 03/13] btrfs: Eliminate PagePrivate for btrfs data pages Goldwyn Rodrigues
2019-08-02 22:00 ` [PATCH 04/13] btrfs: Add a simple buffered iomap write Goldwyn Rodrigues
2019-08-05 0:11 ` Dave Chinner
2019-08-22 15:05 ` Goldwyn Rodrigues
2019-08-02 22:00 ` [PATCH 05/13] btrfs: Add CoW in iomap based writes Goldwyn Rodrigues
2019-08-05 0:13 ` Dave Chinner
2019-08-22 15:01 ` Goldwyn Rodrigues
2019-08-02 22:00 ` [PATCH 06/13] btrfs: remove buffered write code made unnecessary Goldwyn Rodrigues
2019-08-02 22:00 ` [PATCH 07/13] btrfs: basic direct read operation Goldwyn Rodrigues
2019-08-12 12:32 ` RITESH HARJANI
2019-08-22 15:00 ` Goldwyn Rodrigues
2019-08-02 22:00 ` [PATCH 08/13] btrfs: Carve out btrfs_get_extent_map_write() out of btrfs_get_blocks_write() Goldwyn Rodrigues
2019-08-02 22:00 ` [PATCH 09/13] btrfs: Rename __endio_write_update_ordered() to btrfs_update_ordered_extent() Goldwyn Rodrigues
2019-08-02 22:00 ` [PATCH 10/13] iomap: use a function pointer for dio submits Goldwyn Rodrigues
2019-08-03 0:21 ` Darrick J. Wong
2019-08-05 16:08 ` Goldwyn Rodrigues
2019-08-04 23:43 ` Dave Chinner
2019-08-05 16:08 ` Goldwyn Rodrigues
2019-08-05 21:54 ` Dave Chinner
2019-08-08 4:26 ` Gao Xiang
2019-08-08 4:52 ` Gao Xiang
2019-08-08 5:49 ` Eric Biggers
2019-08-08 6:28 ` Gao Xiang
2019-08-08 8:16 ` Dave Chinner
2019-08-08 8:57 ` Gao Xiang
2019-08-08 9:29 ` Gao Xiang
2019-08-08 11:21 ` Gao Xiang
2019-08-08 13:11 ` Gao Xiang
2019-08-09 20:45 ` Matthew Wilcox [this message]
2019-08-09 23:45 ` Gao Xiang
2019-08-10 0:31 ` Eric Biggers
2019-08-10 0:50 ` Eric Biggers
2019-08-10 1:34 ` Gao Xiang
2019-08-10 1:13 ` Gao Xiang
2019-08-10 0:17 ` Eric Biggers
2019-08-02 22:00 ` [PATCH 11/13] btrfs: Use iomap_dio_rw for performing direct I/O writes Goldwyn Rodrigues
2019-08-02 22:00 ` [PATCH 12/13] btrfs: Remove btrfs_dio_data and __btrfs_direct_write Goldwyn Rodrigues
2019-08-02 22:00 ` [PATCH 13/13] btrfs: update inode size during bio completion Goldwyn Rodrigues
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190809204517.GR5482@bombadil.infradead.org \
--to=willy@infradead.org \
--cc=RGoldwyn@suse.com \
--cc=darrick.wong@oracle.com \
--cc=david@fromorbit.com \
--cc=gaoxiang25@huawei.com \
--cc=hch@lst.de \
--cc=linux-btrfs@vger.kernel.org \
--cc=linux-erofs@lists.ozlabs.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=miaoxie@huawei.com \
--cc=ruansy.fnst@cn.fujitsu.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).