From: Tejun Heo Date: Fri, 22 May 2015 21:13:47 +0000 (-0400) Subject: writeback: make bdi_has_dirty_io() take multiple bdi_writeback's into account X-Git-Tag: omap-for-v4.2/fixes-rc1^2~117^2~52 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=95a46c65e3c09edb9f17dabf2dc16670cd328739;p=pandora-kernel.git writeback: make bdi_has_dirty_io() take multiple bdi_writeback's into account bdi_has_dirty_io() used to only reflect whether the root wb (bdi_writeback) has dirty inodes. For cgroup writeback support, it needs to take all active wb's into account. If any wb on the bdi has dirty inodes, bdi_has_dirty_io() should return true. To achieve that, as inode_wb_list_{move|del}_locked() now keep track of the dirty state transition of each wb, the number of dirty wbs can be counted in the bdi; however, bdi is already aggregating wb->avg_write_bandwidth which can easily be guaranteed to be > 0 when there are any dirty inodes by ensuring wb->avg_write_bandwidth can't dip below 1. bdi_has_dirty_io() can simply test whether bdi->tot_write_bandwidth is zero or not. While this bumps the value of wb->avg_write_bandwidth to one when it used to be zero, this shouldn't cause any meaningful behavior difference. bdi_has_dirty_io() is made an inline function which tests whether ->tot_write_bandwidth is non-zero. Also, WARN_ON_ONCE()'s on its value are added to inode_wb_list_{move|del}_locked(). Signed-off-by: Tejun Heo Cc: Jens Axboe Cc: Jan Kara Signed-off-by: Jens Axboe --- Reading git-diff-tree failed