nilfs2: add bdev freeze/thaw support

Nilfs hasn't supported the freeze/thaw feature because it didn't work
due to the peculiar design that multiple super block instances could
be allocated for a device.  This limitation was removed by the patch
"nilfs2: do not allocate multiple super block instances for a device".

So now this adds the freeze/thaw support to nilfs.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

1 files changed, 2 insertions, 0 deletions

diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index 56350bf1f79f..172ad4257494 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -191,6 +191,8 @@ int nilfs_transaction_begin(struct super_block *sb,
         if (ret > 0)
                 return 0;
 
+        vfs_check_frozen(sb, SB_FREEZE_WRITE);
+
         sbi = NILFS_SB(sb);
         nilfs = sbi->s_nilfs;
         down_read(&nilfs->ns_segctor_sem);