[PATCH 2/2] xfs: push stale, pinned buffers on trylock failures

[Christoph Hellwig]

> -	/* Attempt to get the semaphore without sleeping,
> -	 * if this does not work then we need to drop the
> -	 * spinlock and do a hard attempt on the semaphore.
> +	/*
> +	 * Attempt to get the semaphore without sleeping first. if we fail then
> +	 * do a blocking lock if requested.
>  	 */

You might as well remove the comment entirely, as it's utterly
pointless.

> -	if (down_trylock(&bp->b_sema)) {
> +	if (xfs_buf_cond_lock(bp)) {
>  		if (!(flags & XBF_TRYLOCK)) {
>  			/* wait for buffer ownership */
>  			xfs_buf_lock(bp);
>  			XFS_STATS_INC(xb_get_locked_waited);
>  		} else {
> -			/* We asked for a trylock and failed, no need
> -			 * to look at file offset and length here, we
> -			 * know that this buffer at least overlaps our
> -			 * buffer and is locked, therefore our buffer
> -			 * either does not exist, or is this buffer.
> -			 */
> +			/* We asked for a trylock and failed.  */
>  			xfs_buf_rele(bp);
>  			XFS_STATS_INC(xb_busy_locked);
>  			return NULL;
>  		}

In case we wait for the lock we now do the log force twice, but that
should be fine.