From: Ted Ts'o <tytso@mit.edu>
To: Andreas Dilger <adilger@dilger.ca>
Cc: djwong@us.ibm.com, Amir Goldstein <amir73il@gmail.com>,
linux-ext4@vger.kernel.org
Subject: Re: On-disk field assignments for metadata checksum and snapshots
Date: Thu, 15 Sep 2011 16:05:12 -0400 [thread overview]
Message-ID: <20110915200512.GF28181@thunk.org> (raw)
In-Reply-To: <7755CB79-FD71-49BE-AF93-0A49CA25CEAC@dilger.ca>
On Thu, Sep 15, 2011 at 01:10:41PM -0600, Andreas Dilger wrote:
>
> This is also a possible alternative, though it makes for more fragments that
> need to be checksummed. I think as a general rule it makes sense to store
> the checksum as the last word in the structure, if possible, so that the
> checksum can be computed in a single call. This is already done for 128-byte
> inodes and for 32-byte group descriptors, but should also be done for the
> s_checksum field in the superblock (i.e. put it after s_reserved instead of
> before).
Or we just zero out the checksum field, checksum the entire data
structure, and then fill in the newly calculated checksum. In fact
that's what I assumed Darrick was going to do.
- Ted
next prev parent reply other threads:[~2011-09-15 20:05 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <E1R4Dby-0005qO-I2@tytso-glaptop.cam.corp.google.com>
2011-09-15 16:01 ` On-disk field assignments for metadata checksum and snapshots Amir Goldstein
2011-09-15 17:57 ` Ted Ts'o
2011-09-16 6:52 ` Amir Goldstein
2011-09-16 11:35 ` Yongqiang Yang
2011-09-16 11:48 ` Amir Goldstein
2011-09-16 12:00 ` Yongqiang Yang
2011-09-16 12:12 ` Amir Goldstein
2011-09-16 14:31 ` Ted Ts'o
2011-09-15 16:55 ` Darrick J. Wong
2011-09-15 17:19 ` Darrick J. Wong
2011-09-15 19:10 ` Andreas Dilger
2011-09-15 20:05 ` Ted Ts'o [this message]
2011-09-15 20:05 ` Darrick J. Wong
2011-09-15 23:26 ` Andreas Dilger
2011-09-15 17:56 ` Ted Ts'o
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