From: Gao Xiang <hsiangkao@linux.alibaba.com>
To: Matthew Wilcox <willy@infradead.org>,
"Darrick J . Wong" <djwong@kernel.org>
Cc: Andreas Gruenbacher <agruenba@redhat.com>,
linux-kernel@vger.kernel.org,
Andreas Gruenbacher <andreas.gruenbacher@gmail.com>,
dsterba@suse.cz, linux-fsdevel@vger.kernel.org,
linux-erofs@lists.ozlabs.org, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v7] iomap: make inline data support more flexible
Date: Tue, 27 Jul 2021 23:04:36 +0800 [thread overview]
Message-ID: <YQAghPSTWdTGYAm5@B-P7TQMD6M-0146.local> (raw)
In-Reply-To: <YQALsvt0UWGW+iMw@casper.infradead.org>
On Tue, Jul 27, 2021 at 02:35:46PM +0100, Matthew Wilcox wrote:
> On Tue, Jul 27, 2021 at 10:20:42AM +0200, David Sterba wrote:
> > On Mon, Jul 26, 2021 at 02:17:02PM +0200, Christoph Hellwig wrote:
> > > > Subject: iomap: Support tail packing
> > >
> > > I can't say I like this "tail packing" language here when we have the
> > > perfectly fine inline wording. Same for various comments in the actual
> > > code.
> >
> > Yes please, don't call it tail-packing when it's an inline extent, we'll
> > use that for btrfs eventually and conflating the two terms has been
> > cofusing users. Except reiserfs, no linux filesystem does tail-packing.
>
> Hmm ... I see what reiserfs does as packing tails of multiple files into
> one block. What gfs2 (and ext4) do is inline data. Erofs packs the
> tail of a single file into the same block as the inode. If I understand
Plus each erofs block can have multiple inodes (thus multi-tail blocks)
oo as long as the meta block itself can fit.
No matter what it's called, it's a kind of inline data (I think inline
means that data mixes with metadata according to [1]). I was called it
tail-block inline initially... whatever.
Hopefully, Darrick could update the v8 title if some concern here.
[1] https://www.kernel.org/doc/Documentation/filesystems/fiemap.txt
Thanks,
Gao Xiang
> what btrfs does correctly, it stores data in the btree. But (like
> gfs2/ext4), it's only for the entire-file-is-small case, not for
> its-just-ten-bytes-into-the-last-block case.
>
> So what would you call what erofs is doing if not tail-packing?
> Wikipedia calls it https://en.wikipedia.org/wiki/Block_suballocation
> which doesn't quite fit. We need a phrase which means "this isn't
> just for small files but for small tails of large files".
next prev parent reply other threads:[~2021-07-27 15:04 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-23 17:41 [PATCH v7] iomap: make inline data support more flexible Gao Xiang
2021-07-23 19:40 ` Matthew Wilcox
2021-07-24 0:54 ` Gao Xiang
2021-07-25 21:39 ` Andreas Grünbacher
2021-07-25 22:16 ` Andreas Gruenbacher
2021-07-26 2:36 ` Gao Xiang
2021-07-26 7:22 ` Andreas Gruenbacher
2021-07-26 7:38 ` Gao Xiang
2021-07-26 21:36 ` Darrick J. Wong
2021-07-26 22:20 ` Andreas Grünbacher
2021-07-26 3:06 ` Matthew Wilcox
2021-07-26 6:56 ` Andreas Gruenbacher
2021-07-26 4:00 ` Gao Xiang
2021-07-26 8:08 ` Andreas Grünbacher
2021-07-26 8:17 ` Gao Xiang
2021-07-26 11:06 ` Andreas Gruenbacher
2021-07-26 12:17 ` Christoph Hellwig
2021-07-26 12:27 ` Andreas Grünbacher
2021-07-26 12:50 ` Gao Xiang
2021-07-26 13:10 ` Andreas Gruenbacher
2021-07-26 13:27 ` Christoph Hellwig
2021-07-27 8:20 ` David Sterba
2021-07-27 13:35 ` Matthew Wilcox
2021-07-27 15:04 ` Gao Xiang [this message]
2021-07-27 16:53 ` David Sterba
2021-07-26 12:32 ` Matthew Wilcox
2021-07-26 13:03 ` Andreas Gruenbacher
2021-07-26 13:12 ` Gao Xiang
2021-07-26 13:30 ` Christoph Hellwig
2021-07-26 8:08 ` Joseph Qi
2021-08-01 10:29 Andreas Gruenbacher
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