summaryrefslogtreecommitdiff
path: root/include/linux/backing-dev.h
diff options
context:
space:
mode:
authorTejun Heo <tj@kernel.org>2015-05-22 17:13:47 -0400
committerJens Axboe <axboe@fb.com>2015-06-02 08:33:36 -0600
commit95a46c65e3c09edb9f17dabf2dc16670cd328739 (patch)
tree2ff8187223f5f5671394dd9ee84719f3ff934a14 /include/linux/backing-dev.h
parent766a9d6e60578f1ef6de71f89f022084f8bffc82 (diff)
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 <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'include/linux/backing-dev.h')
-rw-r--r--include/linux/backing-dev.h10
1 files changed, 9 insertions, 1 deletions
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 3c8403c012ce..0839e44105bd 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -29,7 +29,6 @@ void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
enum wb_reason reason);
void bdi_start_background_writeback(struct backing_dev_info *bdi);
void wb_workfn(struct work_struct *work);
-bool bdi_has_dirty_io(struct backing_dev_info *bdi);
void wb_wakeup_delayed(struct bdi_writeback *wb);
extern spinlock_t bdi_lock;
@@ -42,6 +41,15 @@ static inline bool wb_has_dirty_io(struct bdi_writeback *wb)
return test_bit(WB_has_dirty_io, &wb->state);
}
+static inline bool bdi_has_dirty_io(struct backing_dev_info *bdi)
+{
+ /*
+ * @bdi->tot_write_bandwidth is guaranteed to be > 0 if there are
+ * any dirty wbs. See wb_update_write_bandwidth().
+ */
+ return atomic_long_read(&bdi->tot_write_bandwidth);
+}
+
static inline void __add_wb_stat(struct bdi_writeback *wb,
enum wb_stat_item item, s64 amount)
{