direct-io: fix AIO regression

The direct-io.c rewrite to use the iov_iter infrastructure stopped updating
the size field in struct dio_submit, and thus rendered the check for
allowing asynchronous completions to always return false.  Fix this by
comparing it to the count of bytes in the iov_iter instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: Tim Chen <tim.c.chen@linux.intel.com>
Tested-by: Tim Chen <tim.c.chen@linux.intel.com>

1 files changed, 4 insertions, 5 deletions

diff --git a/fs/direct-io.c b/fs/direct-io.c
index 194d0d122cae..17e39b047de5 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -71,7 +71,6 @@ struct dio_submit {
                                            been performed at the start of a
                                            write */
         int pages_in_io;                /* approximate total IO pages */
-        size_t  size;                   /* total request size (doesn't change)*/
         sector_t block_in_file;         /* Current offset into the underlying
                                            file in dio_block units. */
         unsigned blocks_available;      /* At block_in_file.  changes */
@@ -1104,7 +1103,8 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
         unsigned blkbits = i_blkbits;
         unsigned blocksize_mask = (1 << blkbits) - 1;
         ssize_t retval = -EINVAL;
-        loff_t end = offset + iov_iter_count(iter);
+        size_t count = iov_iter_count(iter);
+        loff_t end = offset + count;
         struct dio *dio;
         struct dio_submit sdio = { 0, };
         struct buffer_head map_bh = { 0, };
@@ -1287,10 +1287,9 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb, struct inode *inode,
          */
         BUG_ON(retval == -EIOCBQUEUED);
         if (dio->is_async && retval == 0 && dio->result &&
-            ((rw == READ) || (dio->result == sdio.size)))
+            (rw == READ || dio->result == count))
                 retval = -EIOCBQUEUED;
-
-        if (retval != -EIOCBQUEUED)
+        else
                 dio_await_completion(dio);
 
         if (drop_refcount(dio) == 0) {