ceph_msg_data_iter_next() gets a page reference from
iov_iter_get_pages2() only to immediately drop it, asserting that the
page is pinned some other way. The assertion is the last caller of
PageWriteback() in the tree, blocking removal of the PG_writeback page
flag accessors.
Remove the assertion, as it is a CONFIG_DEBUG_VM-only check of an
assumption the FIXME comment already documents. Converting to
iov_iter_extract_pages() instead was considered, but the messenger never
releases what it extracts, so it would still rely entirely on the caller
holding the pages. That would be just as much of an abuse of the API, so
leave it as-is for now.
Signed-off-by: Tal Zussman <tz2294@columbia.edu>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
f75987e543