aio: use cancellation list lazily

Cancelling kiocbs requires adding them to a per kioctx linked list,
which is one of the few things we need to take the kioctx lock for in
the fast path.  But most kiocbs can't be cancelled - so if we just do
this lazily, we can avoid quite a bit of locking overhead.

While we're at it, instead of using a flag bit switch to using ki_cancel
itself to indicate that a kiocb has been cancelled/completed.  This lets
us get rid of ki_flags entirely.

[akpm@linux-foundation.org: remove buggy BUG()]
Signed-off-by: Kent Overstreet <koverstreet@google.com>
Cc: Zach Brown <zab@redhat.com>
Cc: Felipe Balbi <balbi@ti.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Asai Thambi S P <asamymuthupa@micron.com>
Cc: Selvan Mani <smani@micron.com>
Cc: Sam Bradshaw <sbradshaw@micron.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Reviewed-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/usb/gadget/inode.c b/drivers/usb/gadget/inode.c
index 994e7433e87a..570c005062ab 100644
--- a/drivers/usb/gadget/inode.c
+++ b/drivers/usb/gadget/inode.c
@@ -533,7 +533,6 @@ static int ep_aio_cancel(struct kiocb *iocb, struct io_event *e)
         local_irq_disable();
         epdata = priv->epdata;
         // spin_lock(&epdata->dev->lock);
-        kiocbSetCancelled(iocb);
         if (likely(epdata && epdata->ep && priv->req))
                 value = usb_ep_dequeue (epdata->ep, priv->req);
         else
@@ -663,7 +662,7 @@ fail:
                 goto fail;
         }
 
-        iocb->ki_cancel = ep_aio_cancel;
+        kiocb_set_cancel_fn(iocb, ep_aio_cancel);
         get_ep(epdata);
         priv->epdata = epdata;
         priv->actual = 0;