aio: lift iov_iter_init() into aio_setup_..._rw()

the only non-trivial detail is that we do it before rw_verify_area(),
so we'd better cap the length ourselves in aio_setup_single_rw()
case (for vectored case rw_copy_check_uvector() will do that for us).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/aio.c b/fs/aio.c
index 435ca29..7816e8e 100644 (file)
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1357,7 +1357,8 @@ static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb,
                                     unsigned long *nr_segs,
                                     size_t *len,
                                     struct iovec **iovec,
-                                    bool compat)
+                                    bool compat,
+                                    struct iov_iter *iter)
 {
        ssize_t ret;
 
@@ -1378,6 +1379,7 @@ static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb,
 
        /* len now reflect bytes instead of segs */
        *len = ret;
+       iov_iter_init(iter, rw, *iovec, *nr_segs, *len);
        return 0;
 }
 
@@ -1385,14 +1387,18 @@ static ssize_t aio_setup_single_vector(struct kiocb *kiocb,
                                       int rw, char __user *buf,
                                       unsigned long *nr_segs,
                                       size_t len,
-                                      struct iovec *iovec)
+                                      struct iovec *iovec,
+                                      struct iov_iter *iter)
 {
+       if (len > MAX_RW_COUNT)
+               len = MAX_RW_COUNT;
        if (unlikely(!access_ok(!rw, buf, len)))
                return -EFAULT;
 
        iovec->iov_base = buf;
        iovec->iov_len = len;
        *nr_segs = 1;
+       iov_iter_init(iter, rw, iovec, *nr_segs, len);
        return 0;
 }
 
@@ -1438,10 +1444,10 @@ rw_common:
 
                if (opcode == IOCB_CMD_PREADV || opcode == IOCB_CMD_PWRITEV)
                        ret = aio_setup_vectored_rw(req, rw, buf, &nr_segs,
-                                               &len, &iovec, compat);
+                                               &len, &iovec, compat, &iter);
                else
                        ret = aio_setup_single_vector(req, rw, buf, &nr_segs,
-                                                 len, iovec);
+                                                 len, iovec, &iter);
                if (!ret)
                        ret = rw_verify_area(rw, file, &req->ki_pos, len);
                if (ret < 0) {
@@ -1463,10 +1469,9 @@ rw_common:
                        file_start_write(file);
 
                if (iter_op) {
-                       iov_iter_init(&iter, rw, iovec, nr_segs, len);
                        ret = iter_op(req, &iter);
                } else {
-                       ret = rw_op(req, iovec, nr_segs, req->ki_pos);
+                       ret = rw_op(req, iter.iov, iter.nr_segs, req->ki_pos);
                }
 
                if (rw == WRITE)