From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tahsin Erdogan <tahsin@google.com>
Subject: Re: First stab at ea inode disk format doc updates
Date: Thu, 22 Jun 2017 11:52:41 -0700
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Cc: Andreas Dilger <adilger@dilger.ca>,
        "Theodore Ts'o" <tytso@mit.edu>, linux-ext4@vger.kernel.org
To: "Darrick J. Wong" <darrick.wong@oracle.com>
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hi Darrick,

> Also -- what is the value of i_mtime (ea inode parent pointer) when the
> refcount > 1?

In the current implementation, xattr inode format is assumed to be in
the new format (refcount in i_ctime and l_i_version, hash in i_atime).
parent xattr e_hash field incorporates xattr inode hash to achieve
strong binding. If hash validation fails, we fallback to old binding
validation (xattr inode i_mtime == parent ino && xattr inode
i_generation == parent i_generation). The idea is to allow migration
from old lustre disks. So, if refcount is valid then value in i_mtime
is not defined.