aio: partial write should not return error code

When an AIO write gets an error after writing some data (eg.  ENOSPC), it
should return the amount written already, not the error.  Just like write()
is supposed to.

This was found by the libaio test suite.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-By: Zach Brown <zach.brown@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 8a48ab0c278d..26c1930889fa 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1347,6 +1347,13 @@ static ssize_t aio_rw_vect_retry(struct kiocb *iocb)
         if ((ret == 0) || (iocb->ki_left == 0))
                 ret = iocb->ki_nbytes - iocb->ki_left;
 
+        /* If we managed to write some out we return that, rather than
+         * the eventual error. */
+        if (opcode == IOCB_CMD_PWRITEV
+            && ret < 0 && ret != -EIOCBQUEUED && ret != -EIOCBRETRY
+            && iocb->ki_nbytes - iocb->ki_left)
+                ret = iocb->ki_nbytes - iocb->ki_left;
+
         return ret;
 }