> @@ -886,8 +880,13 @@
>  				has_deps = (*bioops.io_countdeps)(bp, 0);
>  			else
>  				has_deps = 0;
> -			bufq = has_deps ? &bufqueues[BQ_LRU] :
> -			    &bufqueues[BQ_AGE];
> +
> +			if(has_deps) {

Put a space after the `if'.

> +				bufq = &bufqueues[BQ_LRU];
> +			} else {
> +				buf_age(bp);

With comparing the code to reuse a buffer in the queue or the code in
the (outer) `then-clause' above, I guess calling buf_age() is not
enough.

> @@ -1186,6 +1184,22 @@
>  }
>  
>  /*
> + * Deal with an invalid buffer (called instead of moving it to BQ_AGE).
> + * Sets its size and count to 0; releases its memory to the pool.
> + * The caller must release the actual buffer header -- currently, this
> + * is called from buf_trim, which brelse()s the buffer, and brelse()
> + * itself, which releases the header at the end of the function.
> + */
> +void buf_age(struct buf *bp)

void
buf_age(...

> +{
> +	bufmem -= bp->b_bufsize;
> +        if (bp->b_bufsize > 0) {
> +                buf_mrelease(bp->b_data, bp->b_bufsize);
> +                bp->b_bcount = bp->b_bufsize = 0;
> +        }

I guess these spaces are cut&paste error.

> @@ -1210,14 +1224,8 @@
>  		simple_unlock(&bqueue_slock);
>  		goto out;
>  	}
> -	size = bp->b_bufsize;
> -	bufmem -= size;
>  	simple_unlock(&bqueue_slock);
> -	if (size > 0) {
> -		buf_mrelease(bp->b_data, size);
> -		bp->b_bcount = bp->b_bufsize = 0;
> -	}
> -
> +	buf_age(bp);

Is it safe to update `bufmem' here?

enami.