make aio_read()/aio_write() return int

that ssize_t is a rudiment of earlier calling conventions; it's been
used only to pass 0 and -E... since last autumn.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/aio.c

@@ -1513,13 +1513,13 @@ static inline void aio_rw_done(struct kiocb *req, ssize_t ret)
 	}
 }
 
-static ssize_t aio_read(struct kiocb *req, const struct iocb *iocb,
+static int aio_read(struct kiocb *req, const struct iocb *iocb,
 			bool vectored, bool compat)
 {
 	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
 	struct iov_iter iter;
 	struct file *file;
-	ssize_t ret;
+	int ret;
 
 	ret = aio_prep_rw(req, iocb);
 	if (ret)
@@ -1541,13 +1541,13 @@ static ssize_t aio_read(struct kiocb *req, const struct iocb *iocb,
 	return ret;
 }
 
-static ssize_t aio_write(struct kiocb *req, const struct iocb *iocb,
+static int aio_write(struct kiocb *req, const struct iocb *iocb,
 			 bool vectored, bool compat)
 {
 	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
 	struct iov_iter iter;
 	struct file *file;
-	ssize_t ret;
+	int ret;
 
 	ret = aio_prep_rw(req, iocb);
 	if (ret)
@@ -1710,7 +1710,7 @@ aio_poll_queue_proc(struct file *file, struct wait_queue_head *head,
 	add_wait_queue(head, &pt->iocb->poll.wait);
 }
 
-static ssize_t aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
+static int aio_poll(struct aio_kiocb *aiocb, const struct iocb *iocb)
 {
 	struct kioctx *ctx = aiocb->ki_ctx;
 	struct poll_iocb *req = &aiocb->poll;
@@ -1775,7 +1775,7 @@ static int __io_submit_one(struct kioctx *ctx, const struct iocb *iocb,
 			   struct iocb __user *user_iocb, bool compat)
 {
 	struct aio_kiocb *req;
-	ssize_t ret;
+	int ret;
 
 	/* enforce forwards compatibility on users */
 	if (unlikely(iocb->aio_reserved2)) {