[Patch] hfsplus oops on image without extends

[Eric Sesterhenn <snakebyte@gmx.de>]

hi,

the following patch fixes an oops with a corrupted hfs+ image.
see http://bugzilla.kernel.org/show_bug.cgi?id=10548 for details.

Problem is that we call hfs_btree_open() from hfsplus_fill_super() to set
HFSPLUS_SB(sb).[ext_tree|cat_tree]
Both trees are still NULL at this moment. If hfs_btree_open() fails for
any reason it calls iput() on the page, which
gets to hfsplus_releasepage() which tries to access HFSPLUS_SB(sb).*
which is still NULL and oopses while dereferencing it.


Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de>

--- linux-2.6/fs/hfsplus/inode.c.orig	2008-05-07 14:37:31.000000000 +0200
+++ linux-2.6/fs/hfsplus/inode.c	2008-05-07 14:38:05.000000000 +0200
@@ -65,6 +65,8 @@ static int hfsplus_releasepage(struct pa
 		BUG();
 		return 0;
 	}
+	it (!tree)
+		return 0;
 	if (tree->node_size >= PAGE_CACHE_SIZE) {
 		nidx = page->index >> (tree->node_size_shift - PAGE_CACHE_SHIFT);
 		spin_lock(&tree->hash_lock);