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From: "J. R. Okajima" <hooanon05@yahoo.co.jp>
Subject: Re: vfs-scale, general questions
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: npiggin@gmail.com, npiggin@kernel.dk, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
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Date: Fri, 21 Jan 2011 15:38:59 +0900
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Miklos Szeredi:
> No it doesn't.  dentry_unhash() doesn't drop the dentry from the hash
> unless it has no other references, cwd being one such ref.

I see.
When chdir() completets before vfs_rename_dir(), the dir will not be
unhashed. It is OK.

Even if the dir is unhashed temporary before chdir(), then the lookup
fallback to ref-walk and i_mutex protects. It is OK too.

Thank you.
J. R. Okajima