From: Sage Weil <sage@newdream.net>
Date: Tue, 30 Mar 2010 20:54:41 +0000 (-0700)
Subject: ceph: fix dentry rehashing on virtual .snap dir
X-Git-Tag: v2.6.34-rc5~17^2~9
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9358c6d4c0264b1572554c49c4b92673ea9a5c72;p=pandora-kernel.git

ceph: fix dentry rehashing on virtual .snap dir

If a lookup fails on the magic .snap directory, we bind it to a magic
snap directory inode in ceph_lookup_finish().  That code assumes the dentry
is unhashed, but a recent server-side change started returning NULL leases
on lookup failure, causing the .snap dentry to be hashed and NULL by
ceph_fill_trace().

This causes dentry hash chain corruption, or a dies when d_rehash()
includes
	BUG_ON(!d_unhashed(entry));

So, avoid processing the NULL dentry lease if it the dentry matches the
snapdir name in ceph_fill_trace().  That allows the lookup completion to
properly bind it to the snapdir inode.  BUG there if dentry is hashed to
be sure.

Signed-off-by: Sage Weil <sage@newdream.net>
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