IB/umem: use get_user_pages_fast() to pin DMA pages

And get rid of the mmap_sem calls, as part of that.  Note that
get_user_pages_fast() will, if necessary, fall back to
__gup_longterm_unlocked(), which takes the mmap_sem as needed.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: John Hubbard <[email protected]>
Reviewed-by: Leon Romanovsky <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Reviewed-by: Ira Weiny <[email protected]>
Cc: Alex Williamson <[email protected]>
Cc: Aneesh Kumar K.V <[email protected]>
Cc: Björn Töpel <[email protected]>
Cc: Daniel Vetter <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Hans Verkuil <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Mauro Carvalho Chehab <[email protected]>
Cc: Mike Rapoport <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 6 insertions, 11 deletions

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 146f98fbf22b..f995b50ee1cc 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -257,16 +257,13 @@ struct ib_umem *ib_umem_get(struct ib_device *device, unsigned long addr,
 	sg = umem->sg_head.sgl;
 
 	while (npages) {
-		down_read(&mm->mmap_sem);
-		ret = get_user_pages(cur_base,
-				     min_t(unsigned long, npages,
-					   PAGE_SIZE / sizeof (struct page *)),
-				     gup_flags | FOLL_LONGTERM,
-				     page_list, NULL);
-		if (ret < 0) {
-			up_read(&mm->mmap_sem);
+		ret = get_user_pages_fast(cur_base,
+					  min_t(unsigned long, npages,
+						PAGE_SIZE /
+						sizeof(struct page *)),
+					  gup_flags | FOLL_LONGTERM, page_list);
+		if (ret < 0)
 			goto umem_release;
-		}
 
 		cur_base += ret * PAGE_SIZE;
 		npages   -= ret;
@@ -274,8 +271,6 @@ struct ib_umem *ib_umem_get(struct ib_device *device, unsigned long addr,
 		sg = ib_umem_add_sg_table(sg, page_list, ret,
 			dma_get_max_seg_size(device->dma_device),
 			&umem->sg_nents);
-
-		up_read(&mm->mmap_sem);
 	}
 
 	sg_mark_end(sg);