NFS: Fix an Oops in NFS unmount
Ensure that the dummy 'root dentry' is invisible to d_find_alias(). If not, then it may be spliced into the tree if a parent directory from the same filesystem gets mounted at a later time. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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@ -57,6 +57,17 @@ static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *i
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/* Circumvent igrab(): we know the inode is not being freed */
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atomic_inc(&inode->i_count);
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/*
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* Ensure that this dentry is invisible to d_find_alias().
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* Otherwise, it may be spliced into the tree by
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* d_materialise_unique if a parent directory from the same
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* filesystem gets mounted at a later time.
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* This again causes shrink_dcache_for_umount_subtree() to
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* Oops, since the test for IS_ROOT() will fail.
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*/
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spin_lock(&dcache_lock);
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list_del_init(&sb->s_root->d_alias);
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spin_unlock(&dcache_lock);
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}
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return 0;
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}
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