cleanup AOP_WRITEPAGE_ACTIVATE use in f2fs

[Christoph Hellwig]

Hi all,

this almost entirely cleans up usage of AOP_WRITEPAGE_ACTIVATE in f2fs.

f2fs_sync_node_pages can still return it in a way that is not handled
by any caller and eventually is propagated to userspace.  This does look
like a bug and needs attention by someone who actually knows the code.

Diffstat:
 checkpoint.c |   22 +++++++++++-----------
 compress.c   |    5 +----
 data.c       |   13 ++++---------
 node.c       |   43 ++++++++++++++++++++-----------------------
 4 files changed, 36 insertions(+), 47 deletions(-)