9p: read only once on O_NONBLOCK

A proper way to handle O_NONBLOCK would be making the requests and
responses happen asynchronously, but this would require serious code
refactoring.

Link: http://lkml.kernel.org/r/20200205003457.24340-2-l29ah@cock.li
Signed-off-by: Sergey Alirzaev <l29ah@cock.li>
Signed-off-by: Dominique Martinet <dominique.martinet@cea.fr>

diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index fe7f0bd..92cd1d8 100644 (file)
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -388,7 +388,10 @@ v9fs_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
        p9_debug(P9_DEBUG_VFS, "count %zu offset %lld\n",
                 iov_iter_count(to), iocb->ki_pos);
 
-       ret = p9_client_read(fid, iocb->ki_pos, to, &err);
+       if (iocb->ki_filp->f_flags & O_NONBLOCK)
+               ret = p9_client_read_once(fid, iocb->ki_pos, to, &err);
+       else
+               ret = p9_client_read(fid, iocb->ki_pos, to, &err);
        if (!ret)
                return err;