fs: don't open code lru_to_page()

Multiple filesystems open code lru_to_page().  Rectify this by moving
the macro from mm_inline (which is specific to lru stuff) to the more
generic mm.h header and start using the macro where appropriate.

No functional changes.

Link: http://lkml.kernel.org/r/20181129104810.23361-1-nborisov@suse.com
Link: https://lkml.kernel.org/r/20181129075301.29087-1-nborisov@suse.com
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Pankaj gupta <pagupta@redhat.com>
Acked-by: "Yan, Zheng" <zyan@redhat.com>		[ceph]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index eb1ce30..832c1759 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -30,6 +30,7 @@
 #include <linux/quotaops.h>
 #include <linux/blkdev.h>
 #include <linux/uio.h>
+#include <linux/mm.h>
 
 #include <cluster/masklog.h>
 
@@ -397,7 +398,7 @@ static int ocfs2_readpages(struct file *filp, struct address_space *mapping,
 	 * Check whether a remote node truncated this file - we just
 	 * drop out in that case as it's not worth handling here.
 	 */
-	last = list_entry(pages->prev, struct page, lru);
+	last = lru_to_page(pages);
 	start = (loff_t)last->index << PAGE_SHIFT;
 	if (start >= i_size_read(inode))
 		goto out_unlock;