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author | Tejun Heo <tj@kernel.org> | 2015-05-23 00:13:47 +0300 |
---|---|---|
committer | Jens Axboe <axboe@fb.com> | 2015-06-02 17:33:36 +0300 |
commit | 95a46c65e3c09edb9f17dabf2dc16670cd328739 (patch) | |
tree | 2ff8187223f5f5671394dd9ee84719f3ff934a14 /include/linux/backing-dev-defs.h | |
parent | 766a9d6e60578f1ef6de71f89f022084f8bffc82 (diff) | |
download | linux-95a46c65e3c09edb9f17dabf2dc16670cd328739.tar.xz |
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-defs.h')
-rw-r--r-- | include/linux/backing-dev-defs.h | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h index d631a61f4023..8c857d723023 100644 --- a/include/linux/backing-dev-defs.h +++ b/include/linux/backing-dev-defs.h @@ -98,7 +98,7 @@ struct bdi_writeback { unsigned long dirtied_stamp; unsigned long written_stamp; /* pages written at bw_time_stamp */ unsigned long write_bandwidth; /* the estimated write bandwidth */ - unsigned long avg_write_bandwidth; /* further smoothed write bw */ + unsigned long avg_write_bandwidth; /* further smoothed write bw, > 0 */ /* * The base dirty throttle rate, re-calculated on every 200ms. @@ -142,7 +142,11 @@ struct backing_dev_info { unsigned int min_ratio; unsigned int max_ratio, max_prop_frac; - atomic_long_t tot_write_bandwidth; /* sum of active avg_write_bw */ + /* + * Sum of avg_write_bw of wbs with dirty inodes. > 0 if there are + * any dirty wbs, which is depended upon by bdi_has_dirty(). + */ + atomic_long_t tot_write_bandwidth; struct bdi_writeback wb; /* the root writeback info for this bdi */ struct bdi_writeback_congested wb_congested; /* its congested state */ |