aio: Kill unneeded kiocb members

The old aio retry infrastucture needed to save the various arguments to
to aio operations. But with the retry infrastructure gone, we can trim
struct kiocb quite a bit.

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>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>

fs/aio.c

@@ -723,8 +723,6 @@ static void kiocb_free(struct kiocb *req)
 		eventfd_ctx_put(req->ki_eventfd);
 	if (req->ki_dtor)
 		req->ki_dtor(req);
-	if (req->ki_iovec != &req->ki_inline_vec)
-		kfree(req->ki_iovec);
 	kmem_cache_free(kiocb_cachep, req);
 }
 
@@ -1054,24 +1052,26 @@ SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
 typedef ssize_t (aio_rw_op)(struct kiocb *, const struct iovec *,
 			    unsigned long, loff_t);
 
-static ssize_t aio_setup_vectored_rw(int rw, struct kiocb *kiocb, bool compat)
+static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb,
+				     int rw, char __user *buf,
+				     unsigned long *nr_segs,
+				     struct iovec **iovec,
+				     bool compat)
 {
 	ssize_t ret;
 
-	kiocb->ki_nr_segs = kiocb->ki_nbytes;
+	*nr_segs = kiocb->ki_nbytes;
 
 #ifdef CONFIG_COMPAT
 	if (compat)
 		ret = compat_rw_copy_check_uvector(rw,
-				(struct compat_iovec __user *)kiocb->ki_buf,
-				kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec,
-				&kiocb->ki_iovec);
+				(struct compat_iovec __user *)buf,
+				*nr_segs, 1, *iovec, iovec);
 	else
 #endif
 		ret = rw_copy_check_uvector(rw,
-				(struct iovec __user *)kiocb->ki_buf,
-				kiocb->ki_nr_segs, 1, &kiocb->ki_inline_vec,
-				&kiocb->ki_iovec);
+				(struct iovec __user *)buf,
+				*nr_segs, 1, *iovec, iovec);
 	if (ret < 0)
 		return ret;
 
@@ -1080,15 +1080,17 @@ static ssize_t aio_setup_vectored_rw(int rw, struct kiocb *kiocb, bool compat)
 	return 0;
 }
 
-static ssize_t aio_setup_single_vector(int rw, struct kiocb *kiocb)
+static ssize_t aio_setup_single_vector(struct kiocb *kiocb,
+				       int rw, char __user *buf,
+				       unsigned long *nr_segs,
+				       struct iovec *iovec)
 {
-	if (unlikely(!access_ok(!rw, kiocb->ki_buf, kiocb->ki_nbytes)))
+	if (unlikely(!access_ok(!rw, buf, kiocb->ki_nbytes)))
 		return -EFAULT;
 
-	kiocb->ki_iovec = &kiocb->ki_inline_vec;
-	kiocb->ki_iovec->iov_base = kiocb->ki_buf;
-	kiocb->ki_iovec->iov_len = kiocb->ki_nbytes;
-	kiocb->ki_nr_segs = 1;
+	iovec->iov_base = buf;
+	iovec->iov_len = kiocb->ki_nbytes;
+	*nr_segs = 1;
 	return 0;
 }
 
@@ -1097,15 +1099,18 @@ static ssize_t aio_setup_single_vector(int rw, struct kiocb *kiocb)
  *	Performs the initial checks and aio retry method
  *	setup for the kiocb at the time of io submission.
  */
-static ssize_t aio_run_iocb(struct kiocb *req, bool compat)
+static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode,
+			    char __user *buf, bool compat)
 {
 	struct file *file = req->ki_filp;
 	ssize_t ret;
+	unsigned long nr_segs;
 	int rw;
 	fmode_t mode;
 	aio_rw_op *rw_op;
+	struct iovec inline_vec, *iovec = &inline_vec;
 
-	switch (req->ki_opcode) {
+	switch (opcode) {
 	case IOCB_CMD_PREAD:
 	case IOCB_CMD_PREADV:
 		mode	= FMODE_READ;
@@ -1126,16 +1131,21 @@ rw_common:
 		if (!rw_op)
 			return -EINVAL;
 
-		ret = (req->ki_opcode == IOCB_CMD_PREADV ||
-		       req->ki_opcode == IOCB_CMD_PWRITEV)
-			? aio_setup_vectored_rw(rw, req, compat)
-			: aio_setup_single_vector(rw, req);
+		ret = (opcode == IOCB_CMD_PREADV ||
+		       opcode == IOCB_CMD_PWRITEV)
+			? aio_setup_vectored_rw(req, rw, buf, &nr_segs,
+						&iovec, compat)
+			: aio_setup_single_vector(req, rw, buf, &nr_segs,
+						  iovec);
 		if (ret)
 			return ret;
 
 		ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes);
-		if (ret < 0)
+		if (ret < 0) {
+			if (iovec != &inline_vec)
+				kfree(iovec);
 			return ret;
+		}
 
 		req->ki_nbytes = ret;
 
@@ -1149,8 +1159,7 @@ rw_common:
 		if (rw == WRITE)
 			file_start_write(file);
 
-		ret = rw_op(req, req->ki_iovec,
-			    req->ki_nr_segs, req->ki_pos);
+		ret = rw_op(req, iovec, nr_segs, req->ki_pos);
 
 		if (rw == WRITE)
 			file_end_write(file);
@@ -1175,6 +1184,9 @@ rw_common:
 		return -EINVAL;
 	}
 
+	if (iovec != &inline_vec)
+		kfree(iovec);
+
 	if (ret != -EIOCBQUEUED) {
 		/*
 		 * There's no easy way to restart the syscall since other AIO's
@@ -1246,12 +1258,11 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 	req->ki_obj.user = user_iocb;
 	req->ki_user_data = iocb->aio_data;
 	req->ki_pos = iocb->aio_offset;
-
-	req->ki_buf = (char __user *)(unsigned long)iocb->aio_buf;
 	req->ki_nbytes = iocb->aio_nbytes;
-	req->ki_opcode = iocb->aio_lio_opcode;
 
-	ret = aio_run_iocb(req, compat);
+	ret = aio_run_iocb(req, iocb->aio_lio_opcode,
+			   (char __user *)(unsigned long)iocb->aio_buf,
+			   compat);
 	if (ret)
 		goto out_put_req;
 

include/linux/aio.h

@@ -36,6 +36,7 @@ struct kiocb {
 	struct kioctx		*ki_ctx;	/* NULL for sync ops */
 	kiocb_cancel_fn		*ki_cancel;
 	void			(*ki_dtor)(struct kiocb *);
+	void			*private;
 
 	union {
 		void __user		*user;
@@ -44,15 +45,7 @@ struct kiocb {
 
 	__u64			ki_user_data;	/* user's data for completion */
 	loff_t			ki_pos;
-
-	void			*private;
-	/* State that we remember to be able to restart/retry  */
-	unsigned short		ki_opcode;
-	size_t			ki_nbytes; 	/* copy of iocb->aio_nbytes */
-	char 			__user *ki_buf;	/* remaining iocb->aio_buf */
-	struct iovec		ki_inline_vec;	/* inline vector */
- 	struct iovec		*ki_iovec;
- 	unsigned long		ki_nr_segs;
+	size_t			ki_nbytes;	/* copy of iocb->aio_nbytes */
 
 	struct list_head	ki_list;	/* the aio core uses this
 						 * for cancellation */