From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Dongjun Shin" <djshin90@gmail.com>
Subject: Re: Proposal to improve filesystem/block snapshot interaction
Date: Tue, 30 Oct 2007 18:35:08 +0900
Message-ID: <7fe698080710300235v3ce49613nfe3c5e733f1b6f5b@mail.gmail.com>
References: <20070927063113.GD2989@sgi.com> <20071030010453.GF27385@sgi.com>
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Cc: "Linux Filesystem Mailing List" <linux-fsdevel@vger.kernel.org>,
	"David Chinner" <dgc@melbourne.sgi.com>,
	"Donald Douwsma" <donaldd@melbourne.sgi.com>,
	"Christoph Hellwig" <hch@infradead.org>,
	"Roger Strassburg" <rls@sgi.com>, "Mark Goodwin" <markgw@sgi.com>,
	"Brett Jon Grandbois" <brettg@melbourne.sgi.com>,
	"Arnd Bergmann" <arnd@arndb.de>
To: "Greg Banks" <gnb@sgi.com>
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On 10/30/07, Greg Banks <gnb@sgi.com> wrote:
>
> BIO_HINT_RELEASE
>     The bio's block extent is no longer in use by the filesystem
>     and will not be read in the future.  Any storage used to back
>     the extent may be released without any threat to filesystem
>     or data integrity.
>

I'd like to second the proposal, but it would be more useful to bring the hint
down to the physical devices.

There is an ongoing discussion about adding 'Trim' ATA command for notifying
the drive about the deleted blocks.

http://www.t13.org/Documents/UploadedDocuments/docs2007/e07154r3-Data_Set_Management_Proposal_for_ATA-ACS2.pdf

This is especially useful for the storage device like Solid State Drive (SSD).

Dongjun