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Message-ID: <20190820062213.GA202784@architecture4>
Date: Tue, 20 Aug 2019 14:22:13 +0800
From: Gao Xiang <gaoxiang25@...wei.com>
To: Qu Wenruo <quwenruo.btrfs@....com>
CC: <miaoxie@...wei.com>, Gao Xiang <hsiangkao@....com>,
"Darrick J. Wong" <darrick.wong@...cle.com>,
Jan Kara <jack@...e.cz>, Christoph Hellwig <hch@...radead.org>,
Amir Goldstein <amir73il@...il.com>,
Dave Chinner <david@...morbit.com>,
linux-kernel <linux-kernel@...r.kernel.org>,
devel <devel@...verdev.osuosl.org>,
Stephen Rothwell <sfr@...b.auug.org.au>,
Richard Weinberger <richard@....at>,
Eric Biggers <ebiggers@...nel.org>,
"Chao Yu" <yuchao0@...wei.com>,
linux-erofs <linux-erofs@...ts.ozlabs.org>,
Al Viro <viro@...iv.linux.org.uk>,
Jaegeuk Kim <jaegeuk@...nel.org>,
"Theodore Y. Ts'o" <tytso@....edu>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"David Sterba" <dsterba@...e.cz>,
Li Guifu <bluce.liguifu@...wei.com>,
Fang Wei <fangwei1@...wei.com>, Pavel Machek <pavel@...x.de>,
linux-fsdevel <linux-fsdevel@...r.kernel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] erofs: move erofs out of staging
Hi Qu,
On Tue, Aug 20, 2019 at 02:04:46PM +0800, Qu Wenruo wrote:
> [...]
>
> And performance is another point.
> That tree-checker in btrfs is as fast/slow as CRC32.
> Not sure how it would be for dm-verity, but I guess it's slower than
> CRC32 if using any strong hash.
Just a word, dm-verity can do simple CRC32 without hash
tree in priciple as well. It is only a time problem.
>
> Anyway, for a RO fs, if it's relying on dm-verify then that's OK for
> real-world usage.
> But as a standalone fs, even it's RO, a verification layer would be a
> great plus.
Yes, again, it's on my schedule at least.
>
> At least when new student developers try fuzzed images on the fs, it
> would be a good surprise other than tons of new bug reports.
>
> >
> >
> >>>
> [...]
> >>>
> >>> Yes, we will do such a debugging tool of course. Actually Li Guifu is now
> >>> developping a erofs-fuse to support old linux versions or other OSes for
> >>> archiveing only use, we will base on that code to develop a better fuzzer
> >>> tool as well.
> >>
> >> Personally speaking, debugging tool is way more important than a running
> >> kernel module/fuse.
> >> It's human trying to write the code, most of time is spent educating
> >> code readers, thus debugging tool is way more important than dead cold code.
> >
> > Agree, Xiang and I have no time to developing this feature now, we are glad very much if you could help
> > us to do it ;)
>
> In fact, since the fs is a RO fs, it could be pretty good educational
> example for any fs newbies. Thus a debug tool which can show the full
> metadata of the fs can really be helpful.
Yes, I think EROFS will be helpful for all fs newbies to understand
the basic fs concepts, and I have received contributions from some
new kernel developers. And again, I will do in my spare time.
I'm dedicated to playing with EROFS in my spare time (rather than
only at work to maintain for our products), so I will do and don't
worry about that.
And I agree with Miao Xie on one word, you can join us as well for
educational reason or whatever if you have some extra time... :)
Thanks,
Gao Xiang
>
> In fact, btrfs-debug-tree (now "btrfs ins dump-tree") leads my way to
> btrfs, and still one of my favourite tool to debug.
>
> Thanks,
> Qu
>
>
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