[ 68/95] tuntap: set SOCK_ZEROCOPY flag during open

[Greg Kroah-Hartman]

3.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jason Wang <jasowang@xxxxxxxxxx>

[ Upstream commit 19a6afb23e5d323e1245baa4e62755492b2f1200 ]

Commit 54f968d6efdbf7dec36faa44fc11f01b0e4d1990
(tuntap: move socket to tun_file) forgets to set SOCK_ZEROCOPY flag, which will
prevent vhost_net from doing zercopy w/ tap. This patch fixes this by setting
it during file open.

Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/net/tun.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2154,6 +2154,8 @@ static int tun_chr_open(struct inode *in
 	set_bit(SOCK_EXTERNALLY_ALLOCATED, &tfile->socket.flags);
 	INIT_LIST_HEAD(&tfile->next);
 
+	sock_set_flag(&tfile->sk, SOCK_ZEROCOPY);
+
 	return 0;
 }
 


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