IB/hfi1: use the new FOLL_LONGTERM flag to get_user_pages_fast()

Use the new FOLL_LONGTERM to get_user_pages_fast() to protect against FS
DAX pages being mapped.

[ira.weiny@intel.com: v3]
  Link: http://lkml.kernel.org/r/20190328084422.29911-6-ira.weiny@intel.com
Link: http://lkml.kernel.org/r/20190328084422.29911-6-ira.weiny@intel.com
Link: http://lkml.kernel.org/r/20190317183438.2057-6-ira.weiny@intel.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Mike Marshall <hubcap@omnibond.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/infiniband/hw/hfi1/user_pages.c

@@ -104,9 +104,9 @@ int hfi1_acquire_user_pages(struct mm_struct *mm, unsigned long vaddr, size_t np
 			    bool writable, struct page **pages)
 {
 	int ret;
+	unsigned int gup_flags = FOLL_LONGTERM | (writable ? FOLL_WRITE : 0);
 
-	ret = get_user_pages_fast(vaddr, npages, writable ? FOLL_WRITE : 0,
-				  pages);
+	ret = get_user_pages_fast(vaddr, npages, gup_flags, pages);
 	if (ret < 0)
 		return ret;