commit c35fc7a5abae9c154dd6f8c0b288462342facd45
author Christoph Hellwig <hch@lst.de> Tue Aug 29 16:13:21 2017 +0200
committer Al Viro <viro@zeniv.linux.org.uk> Mon Sep 04 19:04:23 2017 -0400
tree 4531ee1324e372e1382f55f09f2c710564af8838
parent 91f9943e1c7b6638f27312d03fe71fcc67b23571

block_dev: support RFW_NOWAIT on block device nodes

All support is already there in the generic code, we just need to wire
it up.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/block_dev.c

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 9941dc8..ea21d18 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1739,6 +1739,8 @@
 	 */
 	filp->f_flags |= O_LARGEFILE;
 
+	filp->f_mode |= FMODE_NOWAIT;
+
 	if (filp->f_flags & O_NDELAY)
 		filp->f_mode |= FMODE_NDELAY;
 	if (filp->f_flags & O_EXCL)
@@ -1891,6 +1893,9 @@
 	if (iocb->ki_pos >= size)
 		return -ENOSPC;
 
+	if ((iocb->ki_flags & (IOCB_NOWAIT | IOCB_DIRECT)) == IOCB_NOWAIT)
+		return -EOPNOTSUPP;
+
 	iov_iter_truncate(from, size - iocb->ki_pos);
 
 	blk_start_plug(&plug);