[PATCH v2] fcntl: allow to set O_DIRECT flag on pipe

[Stanislav Kinsburskiy <skinsbursky@virtuozzo.com>]

With packetized mode for pipes, it's not possible to set O_DIRECT on pipe file
via sys_fcntl, because of unsupported sanity checks.
Ability to set this flag will be used by CRIU to migrate packetized pipes.

v2:
Fixed typos and mode variable to check.

Signed-off-by: Stanislav Kinsburskiy <skinsbursky@virtuozzo.com>
---
 fs/fcntl.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/fcntl.c b/fs/fcntl.c
index ee85cd4..350a2c8 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -51,7 +51,8 @@ static int setfl(int fd, struct file * filp, unsigned long arg)
 	       if (arg & O_NDELAY)
 		   arg |= O_NONBLOCK;
 
-	if (arg & O_DIRECT) {
+	/* Pipe packetized mode is controlled by O_DIRECT flag */
+	if (!S_ISFIFO(filp->f_inode->i_mode) && (arg & O_DIRECT)) {
 		if (!filp->f_mapping || !filp->f_mapping->a_ops ||
 			!filp->f_mapping->a_ops->direct_IO)
 				return -EINVAL;