On Thu, 22 Apr 1999, Andrea Arcangeli wrote:

> I think there's another subtle bug in set_blocksize() and
> invalidate_buffers(). The problem is that buffers can be moved across
> lists and can be moved across the same list while we are sleeping on a
> locked buffer. This patch address the problem. I never run it on a clean
> 2.2.6, but I am doing these things in my sligthly rewritten buffer.c. It
> address also the problem described by Alexander in a safer way because
> performances after set_blocksize run, are really not an issue, so we can
					^^^^^^^^^^^^^^^^^^^^^^^
					Excuse me, why? Lots of
filesystems do it in read_super(). AFAICS you've just added an overhead to
mount().

> be lazy.

> My patch looks at least safe to me, but probably is better that somebody
> will try out it before inclusion (maybe a simple pre-patch will be ok).
> 
> Ah, and it fix also the buffer-dirty-in-freelist leakage.

[snip]
> @@ -653,10 +629,13 @@
>  	 * around on the free list, and we can get in a loop if we are not careful.
>  	 */
>  	for(nlist = 0; nlist < NR_LIST; nlist++) {
> +	refiled:
>  		bh = lru_list[nlist];
>  		for (i = nr_buffers_type[nlist]*2 ; --i > 0 ; bh = bhnext) {
>  			if(!bh)
>  				break;
> +			if (bh->b_list != nlist)
> +				goto refiled;

	Ahem... Busy-waiting is fun, ain't it? What did you really mean
in the chunk above?
							Al


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