tmpfs: enable NOSEC optimization

Let tmpfs into the NOSEC optimization (avoiding file_remove_suid()
overhead on most common writes): set MS_NOSEC on its superblocks.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/shmem.c b/mm/shmem.c
index db72d8e44ec62d3d7871deb22c5bef24b5a86866..fe5ae6962ab347a9d0f79482fae89b25f78659e1 100644 (file)
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2373,6 +2373,7 @@ int shmem_fill_super(struct super_block *sb, void *data, int silent)
                }
        }
        sb->s_export_op = &shmem_export_ops;
+       sb->s_flags |= MS_NOSEC;
 #else
        sb->s_flags |= MS_NOUSER;
 #endif