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/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 1e2872b..a082709 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -412,10 +412,10 @@
 	pgoff = offset >> PAGE_SHIFT;
 
 	i_size_write(inode, offset);
-	mutex_lock(&mapping->i_mmap_mutex);
+	i_mmap_lock_write(mapping);
 	if (!RB_EMPTY_ROOT(&mapping->i_mmap))
 		hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
-	mutex_unlock(&mapping->i_mmap_mutex);
+	i_mmap_unlock_write(mapping);
 	truncate_hugepages(inode, offset);
 	return 0;
 }