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>

1 files changed, 11 insertions, 6 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 435ca29eca31..7816e8ec3c0e 100644
--- 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)