From: Rolf Eike Beer <eike-kernel@sf-tec.de>
To: linux-kernel@vger.kernel.org
Subject: [2.4.23-pre3] Possible bug in fs/buffer.c
Date: Mon, 8 Sep 2003 17:15:09 +0200
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This is __put_unused_buffer_head from fs/buffer.c, lines 1156 to 1171:


static void __put_unused_buffer_head(struct buffer_head * bh)
{
	if (unlikely(buffer_attached(bh)))
		BUG();
	if (nr_unused_buffer_heads >= MAX_UNUSED_BUFFERS) {
		kmem_cache_free(bh_cachep, bh);
	} else {
		bh->b_dev = B_FREE;
===>		bh->b_blocknr = -1;		<===
		bh->b_this_page = NULL;

		nr_unused_buffer_heads++;
		bh->b_next_free = unused_list;
		unused_list = bh;
	}
}

In include/linux/fs.h "struct buffer_head" is defined this way:

struct buffer_head {
        /* First cache line: */
        struct buffer_head *b_next;     /* Hash queue list */
        unsigned long b_blocknr;        /* block number */
...

So this line (and line 1205, which is the same) is either ugly (and someone
meant ~0UL or something similar) or completely bogus. Same way in 
2.6.0-test4-bk10/fs/buffer.c, line 1031 (b_blocknr is a sector_t, which is an
unsigned long).

Comments?

Eike
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