genwqe: convert get_user_pages() --> pin_user_pages()

This code was using get_user_pages*(), in a "Case 2" scenario
(DMA/RDMA), using the categorization from [1]. That means that it's
time to convert the get_user_pages*() + put_page() calls to
pin_user_pages*() + unpin_user_pages() calls.

There is some helpful background in [2]: basically, this is a small
part of fixing a long-standing disconnect between pinning pages, and
file systems' use of those pages.

[1] Documentation/core-api/pin_user_pages.rst

[2] "Explicit pinning of user-space pages":
    https://lwn.net/Articles/807108/

Cc: Frank Haverkamp <haver@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Link: https://lore.kernel.org/r/20200518015237.1568940-1-jhubbard@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/genwqe/card_utils.c b/drivers/misc/genwqe/card_utils.c
index 2e1c4d2..60460a0 100644 (file)
--- a/drivers/misc/genwqe/card_utils.c
+++ b/drivers/misc/genwqe/card_utils.c
@@ -515,30 +515,6 @@ int genwqe_free_sync_sgl(struct genwqe_dev *cd, struct genwqe_sgl *sgl)
 }
 
 /**
- * genwqe_free_user_pages() - Give pinned pages back
- *
- * Documentation of get_user_pages is in mm/gup.c:
- *
- * If the page is written to, set_page_dirty (or set_page_dirty_lock,
- * as appropriate) must be called after the page is finished with, and
- * before put_page is called.
- */
-static int genwqe_free_user_pages(struct page **page_list,
-                       unsigned int nr_pages, int dirty)
-{
-       unsigned int i;
-
-       for (i = 0; i < nr_pages; i++) {
-               if (page_list[i] != NULL) {
-                       if (dirty)
-                               set_page_dirty_lock(page_list[i]);
-                       put_page(page_list[i]);
-               }
-       }
-       return 0;
-}
-
-/**
  * genwqe_user_vmap() - Map user-space memory to virtual kernel memory
  * @cd:         pointer to genwqe device
  * @m:          mapping params
@@ -597,18 +573,18 @@ int genwqe_user_vmap(struct genwqe_dev *cd, struct dma_mapping *m, void *uaddr,
        m->dma_list = (dma_addr_t *)(m->page_list + m->nr_pages);
 
        /* pin user pages in memory */
-       rc = get_user_pages_fast(data & PAGE_MASK, /* page aligned addr */
+       rc = pin_user_pages_fast(data & PAGE_MASK, /* page aligned addr */
                                 m->nr_pages,
                                 m->write ? FOLL_WRITE : 0,     /* readable/writable */
                                 m->page_list); /* ptrs to pages */
        if (rc < 0)
-               goto fail_get_user_pages;
+               goto fail_pin_user_pages;
 
-       /* assumption: get_user_pages can be killed by signals. */
+       /* assumption: pin_user_pages can be killed by signals. */
        if (rc < m->nr_pages) {
-               genwqe_free_user_pages(m->page_list, rc, m->write);
+               unpin_user_pages_dirty_lock(m->page_list, rc, m->write);
                rc = -EFAULT;
-               goto fail_get_user_pages;
+               goto fail_pin_user_pages;
        }
 
        rc = genwqe_map_pages(cd, m->page_list, m->nr_pages, m->dma_list);
@@ -618,9 +594,9 @@ int genwqe_user_vmap(struct genwqe_dev *cd, struct dma_mapping *m, void *uaddr,
        return 0;
 
  fail_free_user_pages:
-       genwqe_free_user_pages(m->page_list, m->nr_pages, m->write);
+       unpin_user_pages_dirty_lock(m->page_list, m->nr_pages, m->write);
 
- fail_get_user_pages:
+ fail_pin_user_pages:
        kfree(m->page_list);
        m->page_list = NULL;
        m->dma_list = NULL;
@@ -650,8 +626,8 @@ int genwqe_user_vunmap(struct genwqe_dev *cd, struct dma_mapping *m)
                genwqe_unmap_pages(cd, m->dma_list, m->nr_pages);
 
        if (m->page_list) {
-               genwqe_free_user_pages(m->page_list, m->nr_pages, m->write);
-
+               unpin_user_pages_dirty_lock(m->page_list, m->nr_pages,
+                                           m->write);
                kfree(m->page_list);
                m->page_list = NULL;
                m->dma_list = NULL;