From: Amir Goldstein <amir73il@gmail.com>
To: "Ted Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger@dilger.ca>, linux-ext4@vger.kernel.org
Subject: Re: Proposed design for big allocation blocks for ext4
Date: Fri, 25 Feb 2011 23:24:33 +0200 [thread overview]
Message-ID: <AANLkTi=j2LCgORZPdusuCEvo55Bed6CVJp0yFwEy7dGa@mail.gmail.com> (raw)
In-Reply-To: <20110225190436.GZ2924@thunk.org>
On Fri, Feb 25, 2011 at 9:04 PM, Ted Ts'o <tytso@mit.edu> wrote:
> On Fri, Feb 25, 2011 at 08:05:43PM +0200, Amir Goldstein wrote:
>>
>> I like your design. very KISS indeed.
>> I am just wondering why should BIGALLOC be INCOMPAT and not RO_COMPAT?
>> After all, ro mount doesn't allocate and RO_COMPAT features are so muc
>> nicer...
>
> I can try to make it be RO_COMPAT, but one thing my design changes is
> that a block group will contain 32768 allocation blocks; so assuming a
> 4k blocks, instead of a block group containing a maximum of 32,768 4k
> blocks comprising 128 MB, a block group would now contain 32,768 1M
> blocks, or 32 GiB, or 8,388,608 4k blocks.
>
> I'm pretty sure that existing kernels have superblock sanity checks
> that will barf if they see this. Still, yeah, I can try allocating
> this as a ROCOMPAT feature, and later on, if people really care, they
> can patch older kernels so they won't freak out when they see a
> BigAlloc file system and can thus successfully mount it read-only.
>
> (Right now existing kernels will complain when s_blocks_per_group is
> greater than blocksize*8.)
>
no problem. just rename s_blocks_per_group to s_bigblocks_per_group
to be compatible with old kernels.
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2011-02-25 21:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-02-25 2:56 Proposed design for big allocation blocks for ext4 Theodore Ts'o
2011-02-25 8:21 ` Andreas Dilger
2011-02-25 9:15 ` Rogier Wolff
2011-02-25 10:01 ` Andreas Dilger
2011-02-25 10:39 ` Rogier Wolff
2011-02-25 12:57 ` Theodore Tso
2011-02-25 18:05 ` Amir Goldstein
2011-02-25 19:04 ` Ted Ts'o
2011-02-25 19:39 ` Andreas Dilger
2011-02-25 21:24 ` Amir Goldstein [this message]
2011-02-25 21:59 ` Joel Becker
2011-02-25 23:40 ` Ted Ts'o
2011-02-26 0:03 ` Joel Becker
2011-02-26 0:31 ` Ted Ts'o
2011-02-26 0:33 ` Joel Becker
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='AANLkTi=j2LCgORZPdusuCEvo55Bed6CVJp0yFwEy7dGa@mail.gmail.com' \
--to=amir73il@gmail.com \
--cc=adilger@dilger.ca \
--cc=linux-ext4@vger.kernel.org \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).