[AIO] cleanup thread based aio fallback code

Clean up the thread based aio fallback code by making use of ki_opcode 
to switch based on the iocb.  Introduce a cancel method for thread based 
fallback that sends a SIGKILL to the thread performing the io.

Signed-off-by: Benjamin LaHaise <bcrl@linux.intel.com>
diff -purN --exclude=description 88_thread_cleanup/fs/aio.c 89_debug_cleanup/fs/aio.c
--- 88_thread_cleanup/fs/aio.c	2005-08-17 13:54:36.000000000 -0400
+++ 89_debug_cleanup/fs/aio.c	2005-08-17 12:40:36.000000000 -0400
@@ -139,7 +139,7 @@ static int aio_setup_ring(struct kioctx 
 				  0);
 	if (IS_ERR((void *)info->mmap_base)) {
 		up_write(&ctx->mm->mmap_sem);
-		printk("mmap err: %ld\n", -info->mmap_base);
+		dprintk("mmap err: %ld\n", -info->mmap_base);
 		info->mmap_size = 0;
 		aio_free_ring(ctx);
 		return -EAGAIN;
@@ -495,6 +495,7 @@ static int __aio_put_req(struct kioctx *
 		BUG();
 	if (likely(req->ki_users))
 		return 0;
+	BUG_ON(!list_empty(&req->ki_wait.wait.task_list));
 	list_del(&req->ki_list);		/* remove from active_reqs */
 	req->ki_cancel = NULL;
 	req->ki_retry = NULL;
@@ -670,7 +671,7 @@ static ssize_t aio_run_iocb(struct kiocb
 	ssize_t ret;
 
 	if (iocb->ki_retried++ > 1024*1024) {
-		printk("Maximal retry count.  Bytes done %Zd\n",
+		printk(KERN_DEBUG "Maximal retry count.  Bytes done %Zd\n",
 			iocb->ki_nbytes - iocb->ki_left);
 		return -EAGAIN;
 	}
@@ -681,7 +682,7 @@ static ssize_t aio_run_iocb(struct kiocb
 	}
 
 	if (!(retry = iocb->ki_retry)) {
-		printk("aio_run_iocb: iocb->ki_retry = NULL\n");
+		printk(KERN_DEBUG "aio_run_iocb: iocb->ki_retry = NULL\n");
 		return 0;
 	}
 
@@ -1992,6 +1993,9 @@ asmlinkage long sys_io_submit(aio_contex
 	/*
 	 * AKPM: should this return a partial result if some of the IOs were
 	 * successfully submitted?
+	 * bcrl: yes.  By returning either the partial result or an error,
+	 * applications can resubmit the requests that were not completed
+	 * to discover the error code returned by the submit path.
 	 */
 	for (i=0; i<nr; i++) {
 		struct iocb __user *user_iocb;