From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: Greg Freemyer <greg.freemyer@gmail.com>
Cc: Andreas Dilger <adilger@sun.com>,
Akira Fujita <a-fujita@rs.jp.nec.com>,
linux-ext4@vger.kernel.org, "Theodore Ts'o" <tytso@mit.edu>,
linux-fsdevel@vger.kernel.org,
Aneesh Kumar <aneesh.kumar@gmail.com>
Subject: Re: [RFC][PATCH 1/7]ext4: Add EXT4_IOC_ADD_GLOBAL_ALLOC_RULE restricts block allocation
Date: Sat, 27 Jun 2009 22:24:00 +0530 [thread overview]
Message-ID: <20090627165400.GA9414@skywalker> (raw)
In-Reply-To: <87f94c370906250547l338fd357s2e51291185bc3b2c@mail.gmail.com>
On Thu, Jun 25, 2009 at 08:47:59AM -0400, Greg Freemyer wrote:
> Aneesh,
>
> Can you provide the below requested info?
>
> Thanks
> Greg
>
> On Tue, Jun 23, 2009 at 8:11 PM, Andreas Dilger<adilger@sun.com> wrote:
> > 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.
> >
Mostly the source. Some of mballoc details are documented in the ols
2008 paper. Regarding some of the functions
ext4_mb_use_preallocated -> allocate from PA
ext4_mb_new_preallocation -> Create new PA.
Source code also have some documentation that explains how mballoc use
PA.
-aneesh
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prev parent reply other threads:[~2009-06-27 16:54 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
2009-06-25 12:47 ` Greg Freemyer
2009-06-27 16:54 ` Aneesh Kumar K.V [this message]
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