linux-ext4 - Re: [PATCH 1/2] fs: Do not dispatch FITRIM through separate super

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]

Message-ID: <20101119145423.GA27919@infradead.org>
Date:	Fri, 19 Nov 2010 09:54:24 -0500
From:	Christoph Hellwig <hch@...radead.org>
To:	Mark Lord <kernel@...savvy.com>
Cc:	Christoph Hellwig <hch@...radead.org>,
	Greg Freemyer <greg.freemyer@...il.com>,
	"Martin K. Petersen" <martin.petersen@...cle.com>,
	James Bottomley <James.Bottomley@...e.de>,
	Jeff Moyer <jmoyer@...hat.com>,
	Matthew Wilcox <matthew@....cx>,
	Josef Bacik <josef@...hat.com>,
	Lukas Czerner <lczerner@...hat.com>, tytso@....edu,
	linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, sandeen@...hat.com
Subject: Re: [PATCH 1/2] fs: Do not dispatch FITRIM through separate
 super_operation

On Fri, Nov 19, 2010 at 09:48:12AM -0500, Mark Lord wrote:
> I'm not sure about the issues on "adapting the block layer" ?
> For FITRIM, the blocks being trimmed would be reserved at the fs level,
> before issuing the discard for them.  So ordering through the block layer
> shouldn't matter much for it.  Does that simplify things?
> 
> I see FITRIM just allocating a page to hold the ranges (for the >1 case)
> and passing that page down through the layers to libata (or any other
> LLD that supports >1 ranges).

Ordering should not be an issue.  What were problems when I tried this
before is that we currently assume in the block layer that discard
bios have a valid bi_sector/bi_size, which is already needed e.g. for
the trivial remapping use for partitions and that they don't have
a payload.  You'd need to teach various places that discard payloads
may have a payload, which contains multiple ranges that have a
sector/len tuple that needs to be remapped and checked in various
places.

--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html