linux-kernel - Q: NFSD readdir in linux-2.6.28

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Date:	Thu, 19 Mar 2009 23:54:04 +0900
From:	hooanon05@...oo.co.jp
To:	David Woodhouse <David.Woodhouse@...el.com>,
	Al Viro <viro@...iv.linux.org.uk>
cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Q: NFSD readdir in linux-2.6.28

Hello David and Al,
I have a question about NFSD readdir.

By the commit 14f7dd632011bb89c035722edd6ea0d90ca6b078
"[PATCH] Copy XFS readdir hack into nfsd code", nfsd_buffered_filldir()
was introduced and nfs3svc_encode_entry_plus() (the 'func' parameter) is
not called from vfs_readdir().

In 2.6.27, when nfs3svc_encode_entry_plus() calls lookup_one_len(), the
i_mutex lock was acquired by vfs_readdir() and it was not a problem.

After the commit (above), nfsd_readdir/nfsd_buffered_readdir/vfs_readdir
calls nfsd_buffered_filldir(), and nfs3svc_encode_entry_plus() is called
later.
In this sequence, lookup_one_len() is called without i_mutex held.

Isn't it a problem?

J. R. Okajima
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