mm: use new helper functions around the i_mmap_mutex

Convert all open coded mutex_lock/unlock calls to the
i_mmap_[lock/unlock]_write() helpers.

Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: "Kirill A. Shutemov" <kirill@shutemov.name>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/filemap_xip.c b/mm/filemap_xip.c
index d8d9fe3..bad746b 100644
--- a/mm/filemap_xip.c
+++ b/mm/filemap_xip.c
@@ -182,7 +182,7 @@
 		return;
 
 retry:
-	mutex_lock(&mapping->i_mmap_mutex);
+	i_mmap_lock_write(mapping);
 	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
 		mm = vma->vm_mm;
 		address = vma->vm_start +
@@ -202,7 +202,7 @@
 			page_cache_release(page);
 		}
 	}
-	mutex_unlock(&mapping->i_mmap_mutex);
+	i_mmap_unlock_write(mapping);
 
 	if (locked) {
 		mutex_unlock(&xip_sparse_mutex);