From 9561a7ade0c205bc2ee035a2ac880478dcc1a024 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Tue, 22 Nov 2016 14:04:40 -0500 Subject: nbd: add multi-connection support NBD can become contended on its single connection. We have to serialize all writes and we can only process one read response at a time. Fix this by allowing userspace to provide multiple connections to a single nbd device. This coupled with block-mq drastically increases performance in multi-process cases. Thanks, Signed-off-by: Josef Bacik Signed-off-by: Jens Axboe --- include/uapi/linux/nbd.h | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/nbd.h b/include/uapi/linux/nbd.h index e08e413d5f71..f063cff178c5 100644 --- a/include/uapi/linux/nbd.h +++ b/include/uapi/linux/nbd.h @@ -38,11 +38,12 @@ enum { }; /* values for flags field */ -#define NBD_FLAG_HAS_FLAGS (1 << 0) /* nbd-server supports flags */ -#define NBD_FLAG_READ_ONLY (1 << 1) /* device is read-only */ -#define NBD_FLAG_SEND_FLUSH (1 << 2) /* can flush writeback cache */ +#define NBD_FLAG_HAS_FLAGS (1 << 0) /* nbd-server supports flags */ +#define NBD_FLAG_READ_ONLY (1 << 1) /* device is read-only */ +#define NBD_FLAG_SEND_FLUSH (1 << 2) /* can flush writeback cache */ /* there is a gap here to match userspace */ -#define NBD_FLAG_SEND_TRIM (1 << 5) /* send trim/discard */ +#define NBD_FLAG_SEND_TRIM (1 << 5) /* send trim/discard */ +#define NBD_FLAG_CAN_MULTI_CONN (1 << 7) /* Server supports multiple connections per export. */ /* userspace doesn't need the nbd_device structure */ -- cgit v1.2.3