linux-ext4 - Re: metadata_csum set but no space in dir leaf for checksum

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Message-ID: <20121014145508.GC6207@thunk.org>
Date:	Sun, 14 Oct 2012 10:55:08 -0400
From:	Theodore Ts'o <tytso@....edu>
To:	Andreas Dilger <adilger@...ger.ca>
Cc:	George Spelvin <linux@...izon.com>, linux-ext4@...r.kernel.org
Subject: Re: metadata_csum set but no space in dir leaf for checksum

On Sun, Oct 14, 2012 at 12:43:47AM -0600, Andreas Dilger wrote:
> 
> This means there was an existing directory block that was completely full and
> could not have the checksum added.  It isn't harmful, the chance of having
> silent corruption in this specific block is very small.

Was this a freshly created ext4 file system with the metadata_csum
checksum, or was this a previously existing ext4 file system where the
metadata_csum feature was added later?

I've pushed an update to the e2fsprogs repository which allows htree
and "ls -c" to actually show us the directory leaf block checksums.
Previously, they were hidden, which means that it's hard to tell
whether a directory had all of its directory blocks properly
checksummed or not.

> The message itself should be quieted though, since there isn't anything to be
> helped by printing it continuously.  I guess there is something missing in
> e2fsck that it doesn't add a checksum to this block, however.

Either that, or somehow there is a case where the directory tail
containing the checksum is getting overwritten, or a directory block
isn't getting a checksum after a htree node split.  The e2fsprogs
changes will hopefully make it easier for us to figure out what is
going on.

					- Ted
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