fs: simplify the generic_write_sync prototype

The kiocb already has the new position, so use that.  The only interesting
case is AIO, where we currently don't bother updating ki_pos.  We're about
to free the kiocb after we're done, so we might as well update it to make
everyone's life simpler.

While we're at it also return the bytes written argument passed in if
we were successful so that the boilerplate error switch code in the
callers can go away.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 9 insertions, 8 deletions

diff --git a/fs/direct-io.c b/fs/direct-io.c
index f7bcc0193dee..3bf3f20f8ecc 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -256,6 +256,7 @@ static ssize_t dio_complete(struct dio *dio, ssize_t ret, bool is_async)
         if (dio->end_io) {
                 int err;
 
+                // XXX: ki_pos??
                 err = dio->end_io(dio->iocb, offset, ret, dio->private);
                 if (err)
                         ret = err;
@@ -265,15 +266,15 @@ static ssize_t dio_complete(struct dio *dio, ssize_t ret, bool is_async)
                 inode_dio_end(dio->inode);
 
         if (is_async) {
-                if (dio->rw & WRITE) {
-                        int err;
-
-                        err = generic_write_sync(dio->iocb, offset,
-                                                 transferred);
-                        if (err < 0 && ret > 0)
-                                ret = err;
-                }
+                /*
+                 * generic_write_sync expects ki_pos to have been updated
+                 * already, but the submission path only does this for
+                 * synchronous I/O.
+                 */
+                dio->iocb->ki_pos += transferred;
 
+                if (dio->rw & WRITE)
+                        ret = generic_write_sync(dio->iocb,  transferred);
                 dio->iocb->ki_complete(dio->iocb, ret, 0);
         }