IB/core: Add support for on demand paging regions

* Extend the umem struct to keep the ODP related data.
* Allocate and initialize the ODP related information in the umem
  (page_list, dma_list) and freeing as needed in the end of the run.
* Store a reference to the process PID struct in the ucontext.  Used to
  safely obtain the task_struct and the mm during fault handling,
  without preventing the task destruction if needed.
* Add 2 helper functions: ib_umem_odp_map_dma_pages and
  ib_umem_odp_unmap_dma_pages. These functions get the DMA addresses
  of specific pages of the umem (and, currently, pin them).
* Support for page faults only - IB core will keep the reference on
  the pages used and call put_page when freeing an ODP umem
  area. Invalidations support will be added in a later patch.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Shachar Raindel <raindel@mellanox.com>
Signed-off-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Majd Dibbiny <majd@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index a51f4091489a..2d83cfd7e6ce 100644
--- a/include/rdma/ib_umem.h
+++ b/include/rdma/ib_umem.h
@@ -38,6 +38,7 @@
 #include <linux/workqueue.h>
 
 struct ib_ucontext;
+struct ib_umem_odp;
 
 struct ib_umem {
         struct ib_ucontext     *context;
@@ -50,6 +51,7 @@ struct ib_umem {
         struct pid             *pid;
         struct mm_struct       *mm;
         unsigned long           diff;
+        struct ib_umem_odp     *odp_data;
         struct sg_table sg_head;
         int             nmap;
         int             npages;