linux-kernel - Re: [PATCH 25/27] nilfs2: block cache for garbage collection

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 18 Sep 2008 04:09:45 +0900 (JST)
From:	Ryusuke Konishi <konishi.ryusuke@....ntt.co.jp>
To:	joern@...fs.org
Cc:	akpm@...ux-foundation.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, kihara.seiji@....ntt.co.jp,
	amagai.yoshiji@....ntt.co.jp
Subject: Re: [PATCH 25/27] nilfs2: block cache for garbage collection

On Wed, 17 Sep 2008 16:41:47 +0200, Jörn Engel wrote:
> On Mon, 15 September 2008 04:08:22 +0900, Ryusuke Konishi wrote:
> > 
> > This adds the cache of on-disk blocks to be moved in garbage
> > collection.  The disk blocks are held with dummy inodes (called
> > gcinodes), and this file provides lookup function of the dummy inodes,
> > and their buffer read function.
> 
> Nice explanation.  Can you add it to the comment header at the top of
> the file?  Unlike the GPL preample, it actually helps non-lawyers. ;)

Well, I see. ;)

> Using dummy inodes is... unusual.  Why can you not use the actual inodes
> those blocks belong to?

Because we have to treat blocks that belong to a same file but have
different checkpoint numbers.  (NILFS2 keeps up multiple
checkpoints/snapshots across GC)

Of course, if the standard inode hash is applicable, I prefer it.
ilookup5 or its variant may be applicable for this.

If so, the remaining problem would be the lock dependencies as you
mentioned before.

> Or alternatively a single inode that simply
> covers the complete physical device?
> 
> Jörn

NILFS2 writes GC blocks per file like other files, so the per file
caches (even separate inodes) are convienient for this end.

Ryusuke
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/