mm: export follow_pte()

DAX will need to implement its own version of page_check_address().  To
avoid duplicating page table walking code, export follow_pte() which
does what we need.

Link: http://lkml.kernel.org/r/1479460644-25076-18-git-send-email-jack@suse.cz
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 4 insertions, 2 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index cec967e93f95..63926492c06a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1210,6 +1210,8 @@ int copy_page_range(struct mm_struct *dst, struct mm_struct *src,
                         struct vm_area_struct *vma);
 void unmap_mapping_range(struct address_space *mapping,
                 loff_t const holebegin, loff_t const holelen, int even_cows);
+int follow_pte(struct mm_struct *mm, unsigned long address, pte_t **ptepp,
+               spinlock_t **ptlp);
 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
         unsigned long *pfn);
 int follow_phys(struct vm_area_struct *vma, unsigned long address,
diff --git a/mm/memory.c b/mm/memory.c
index 8b7f0656a921..edd899d0decb 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3817,8 +3817,8 @@ out:
         return -EINVAL;
 }
 
-static inline int follow_pte(struct mm_struct *mm, unsigned long address,
-                             pte_t **ptepp, spinlock_t **ptlp)
+int follow_pte(struct mm_struct *mm, unsigned long address, pte_t **ptepp,
+               spinlock_t **ptlp)
 {
         int res;