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From: Andreas Dilger <adilger@sun.com>
To: Greg Freemyer <greg.freemyer@gmail.com>
Cc: Akira Fujita <a-fujita@rs.jp.nec.com>,
	linux-ext4@vger.kernel.org, "Theodore Ts'o" <tytso@mit.edu>,
	linux-fsdevel@vger.kernel.org
Subject: Re: [RFC][PATCH 1/7]ext4: Add EXT4_IOC_ADD_GLOBAL_ALLOC_RULE	restricts block allocation
Date: Wed, 24 Jun 2009 02:11:58 +0200	[thread overview]
Message-ID: <20090624001158.GQ31668@webber.adilger.int> (raw)
In-Reply-To: <87f94c370906231702m6dde1402o9d2738f97f4b7df9@mail.gmail.com>

On Jun 23, 2009  20:02 -0400, Greg Freemyer wrote:
> On Tue, Jun 23, 2009 at 7:19 PM, Andreas Dilger<adilger@sun.com> wrote:
> > On Jun 23, 2009  17:25 +0900, Akira Fujita wrote:
> >> alloc_flag of ext4_alloc_rule structure is set as "mandatory" or "advisory".
> >> Restricted blocks with "mandatory" are never used by block allocator.
> >> But in "advisory" case, block allocator is allowed to use restricted blocks
> >> when there are no free blocks on FS.
> >
> > Would it make more sense to implement the range protections via the
> > existing preallocation ranges (PA)?  An inode can have multiple
> > PAs attached to it to have it prefer allocations from that range.
> >
> > We could also attach PAs to the superblock to prevent other files from
> > allocating out of those ranges.  This would work better with the existing
> > allocation code instead of creating a second similar mechanism.
> 
> Where can I find documentation about how PA works?  Or is it just in
> the source?  If so, what are one or two calls that cause the PA ranges
> to be set, etc.

Aneesh is the expert on the preallocation code.

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.

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  reply	other threads:[~2009-06-24  0:12 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-06-23  8:25 [RFC][PATCH 1/7]ext4: Add EXT4_IOC_ADD_GLOBAL_ALLOC_RULE restricts block allocation Akira Fujita
2009-06-23 23:19 ` Andreas Dilger
2009-06-24  0:02   ` Greg Freemyer
2009-06-24  0:11     ` Andreas Dilger [this message]
2009-06-25 12:47       ` Greg Freemyer
2009-06-27 16:54         ` Aneesh Kumar K.V

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