fs: split generic and aio kiocb

Most callers in the kernel want to perform synchronous file I/O, but
still have to bloat the stack with a full struct kiocb.  Split out
the parts needed in filesystem code from those in the aio code, and
only allocate those needed to pass down argument on the stack.  The
aio code embedds the generic iocb in the one it allocates and can
easily get back to it by using container_of.

Also add a ->ki_complete method to struct kiocb, this is used to call
into the aio code and thus removes the dependency on aio for filesystems
impementing asynchronous operations.  It will also allow other callers
to substitute their own completion callback.

We also add a new ->ki_flags field to work around the nasty layering
violation recently introduced in commit 5e33f6 ("usb: gadget: ffs: add
eventfd notification about ffs events").

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 6 insertions, 4 deletions

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
index 175c9956cbe3..b64538b498dc 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -655,9 +655,10 @@ static void ffs_user_copy_worker(struct work_struct *work)
                 unuse_mm(io_data->mm);
         }
 
-        aio_complete(io_data->kiocb, ret, ret);
+        io_data->kiocb->ki_complete(io_data->kiocb, ret, ret);
 
-        if (io_data->ffs->ffs_eventfd && !io_data->kiocb->ki_eventfd)
+        if (io_data->ffs->ffs_eventfd &&
+            !(io_data->kiocb->ki_flags & IOCB_EVENTFD))
                 eventfd_signal(io_data->ffs->ffs_eventfd, 1);
 
         usb_ep_free_request(io_data->ep, io_data->req);
diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c
index 200f9a584064..a4a80694f607 100644
--- a/drivers/usb/gadget/legacy/inode.c
+++ b/drivers/usb/gadget/legacy/inode.c
@@ -469,7 +469,7 @@ static void ep_user_copy_worker(struct work_struct *work)
                 ret = -EFAULT;
 
         /* completing the iocb can drop the ctx and mm, don't touch mm after */
-        aio_complete(iocb, ret, ret);
+        iocb->ki_complete(iocb, ret, ret);
 
         kfree(priv->buf);
         kfree(priv->to_free);
@@ -497,7 +497,8 @@ static void ep_aio_complete(struct usb_ep *ep, struct usb_request *req)
                 kfree(priv);
                 iocb->private = NULL;
                 /* aio_complete() reports bytes-transferred _and_ faults */
-                aio_complete(iocb, req->actual ? req->actual : req->status,
+
+                iocb->ki_complete(iocb, req->actual ? req->actual : req->status,
                                 req->status);
         } else {
                 /* ep_copy_to_user() won't report both; we hide some faults */