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Commit a10db50a authored by Trond Myklebust's avatar Trond Myklebust
Browse files

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: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent a5576cfa

fs/nfs/getroot.c

+11 −0
Original line number Diff line number Diff line
@@ -57,6 +57,17 @@ static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *i 
		}

		/* Circumvent igrab(): we know the inode is not being freed */

		atomic_inc(&inode->i_count);

		/*

		 * Ensure that this dentry is invisible to d_find_alias().

		 * Otherwise, it may be spliced into the tree by

		 * d_materialise_unique if a parent directory from the same

		 * filesystem gets mounted at a later time.

		 * This again causes shrink_dcache_for_umount_subtree() to

		 * Oops, since the test for IS_ROOT() will fail.

		 */

		spin_lock(&dcache_lock);

		list_del_init(&sb->s_root->d_alias);

		spin_unlock(&dcache_lock);

	}

	return 0;

}