tree 674d81536ade2aa5d50dbfdee93e315c0f7112ea
parent d2d11adecc829fed60e84656b1435f17642628eb
author Tejun Heo <tj@kernel.org> 1420575271 -0500
committer Tejun Heo <tj@kernel.org> 1420575271 -0500

writeback: make cyclic writeback cursor cgroup writeback aware

address_space->writeback_index keeps track of where to write next for
cyclic writebacks.  When cgroup writeback is used, an adress_space can
be written back by multiple wb's (bdi_writeback's) and sharing the
cyclic cursor across them doesn't make sense.

This patch adds inode_cgwb_link->writeback_index and introduces and
uses mapping_writeback_index_wbc() to determine the writeback cursor
to use.  If the writeback_control in effect indicates that non-root
cgroup writeback is in progress, the matching inode_cgwb_link's
writeback_index is used; otherwise, the mapping one is used.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>