From: Chris Mason <mason@suse.com>
Fix for sys_io_cancel to work properly with retries when a cancel
method is specified for an iocb. Needed with pipe AIO support.
There's a bug in my aio cancel patch, aio_complete still makes an event
for cancelled iocbs. If nobody asks for this event, we effectively leak
space in the event ring buffer. I've attached a new aio_cancel patch
that just skips the event creation for canceled iocbs.
aio.c | 10 +++++++++-
1 files changed, 9 insertions(+), 1 deletion(-)
Index: linux.aio/fs/aio.c
diff -upN reference/fs/aio.c current/fs/aio.c
--- reference/fs/aio.c 2004-04-09 13:23:19.000000000 -0700
+++ current/fs/aio.c 2004-04-09 13:23:20.000000000 -0700
@@ -938,6 +938,13 @@ int fastcall aio_complete(struct kiocb *
if (iocb->ki_run_list.prev && !list_empty(&iocb->ki_run_list))
list_del_init(&iocb->ki_run_list);
+ /*
+ * cancelled requests don't get events, userland was given one
+ * when the event got cancelled.
+ */
+ if (kiocbIsCancelled(iocb))
+ goto put_rq;
+
ring = kmap_atomic(info->ring_pages[0], KM_IRQ1);
tail = info->tail;
@@ -970,7 +977,7 @@ int fastcall aio_complete(struct kiocb *
iocb->ki_retried,
iocb->ki_nbytes - iocb->ki_left, iocb->ki_nbytes,
iocb->ki_kicked, iocb->ki_queued, aio_run, aio_wakeups);
-
+put_rq:
/* everything turned out well, dispose of the aiocb. */
ret = __aio_put_req(ctx, iocb);
@@ -1636,6 +1643,7 @@ asmlinkage long sys_io_cancel(aio_contex
if (kiocb && kiocb->ki_cancel) {
cancel = kiocb->ki_cancel;
kiocb->ki_users ++;
+ kiocbSetCancelled(kiocb);
} else
cancel = NULL;
spin_unlock_irq(&ctx->ctx_lock);