libibverbs: Add dmabuf fd field to struct ibv_buf

Add an int dmabuf_fd field to struct ibv_buf so that providers can
store the DMA-buf file descriptor directly in the common buffer
abstraction.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>

libibverbs/driver.h

diff --git a/libibverbs/driver.h b/libibverbs/driver.h
index 45a0b1d..4d73194 100644
--- a/libibverbs/driver.h
+++ b/libibverbs/driver.h
@@ -54,6 +54,7 @@
 	void *addr;
 	size_t size;
 	struct ibv_pd *pd;
+	int dmabuf_fd;
 };
 
 static inline void ibv_buf_init(struct ibv_buf *buf, struct ibv_pd *pd,
@@ -62,6 +63,14 @@
 	buf->pd = pd;
 	buf->addr = addr;
 	buf->size = size;
+	buf->dmabuf_fd = -1;
+}
+
+static inline void ibv_buf_init_dmabuf(struct ibv_buf *buf, struct ibv_pd *pd,
+				       void *addr, size_t size, int fd)
+{
+	ibv_buf_init(buf, pd, addr, size);
+	buf->dmabuf_fd = fd;
 }
 
 enum {