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authorTejun Heo <tj@kernel.org>2015-05-22 17:13:30 -0400
committerJens Axboe <axboe@fb.com>2015-06-02 08:33:34 -0600
commitf0054bb1e1f3be03cc33369df640db97f10f6172 (patch)
treec838fdd0897adc178f93b19e2998e95c978c23fa /mm
parentde1fff37b2781f9caae7bbb7b79fa788a9bb1115 (diff)
writeback: move backing_dev_info->wb_lock and ->worklist into bdi_writeback
Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback) and the role of the separation is unclear. For cgroup support for writeback IOs, a bdi will be updated to host multiple wb's where each wb serves writeback IOs of a different cgroup on the bdi. To achieve that, a wb should carry all states necessary for servicing writeback IOs for a cgroup independently. This patch moves bdi->wb_lock and ->worklist into wb. * The lock protects bdi->worklist and bdi->wb.dwork scheduling. While moving, rename it to wb->work_lock as wb->wb_lock is confusing. Also, move wb->dwork downwards so that it's colocated with the new ->work_lock and ->work_list fields. * bdi_writeback_workfn() -> wb_workfn() bdi_wakeup_thread_delayed(bdi) -> wb_wakeup_delayed(wb) bdi_wakeup_thread(bdi) -> wb_wakeup(wb) bdi_queue_work(bdi, ...) -> wb_queue_work(wb, ...) __bdi_start_writeback(bdi, ...) -> __wb_start_writeback(wb, ...) get_next_work_item(bdi) -> get_next_work_item(wb) * bdi_wb_shutdown() is renamed to wb_shutdown() and now takes @wb. The function contained parts which belong to the containing bdi rather than the wb itself - testing cap_writeback_dirty and bdi_remove_from_list() invocation. Those are moved to bdi_unregister(). * bdi_wb_{init|exit}() are renamed to wb_{init|exit}(). Initializations of the moved bdi->wb_lock and ->work_list are relocated from bdi_init() to wb_init(). * As there's still only one bdi_writeback per backing_dev_info, all uses of bdi->state are mechanically replaced with bdi->wb.state introducing no behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Jens Axboe <axboe@kernel.dk> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'mm')
-rw-r--r--mm/backing-dev.c59
1 files changed, 28 insertions, 31 deletions
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 9a6c472ebd0b..597f0cec8405 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -261,7 +261,7 @@ int bdi_has_dirty_io(struct backing_dev_info *bdi)
}
/*
- * This function is used when the first inode for this bdi is marked dirty. It
+ * This function is used when the first inode for this wb is marked dirty. It
* wakes-up the corresponding bdi thread which should then take care of the
* periodic background write-out of dirty inodes. Since the write-out would
* starts only 'dirty_writeback_interval' centisecs from now anyway, we just
@@ -274,15 +274,15 @@ int bdi_has_dirty_io(struct backing_dev_info *bdi)
* We have to be careful not to postpone flush work if it is scheduled for
* earlier. Thus we use queue_delayed_work().
*/
-void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi)
+void wb_wakeup_delayed(struct bdi_writeback *wb)
{
unsigned long timeout;
timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
- spin_lock_bh(&bdi->wb_lock);
- if (test_bit(WB_registered, &bdi->wb.state))
- queue_delayed_work(bdi_wq, &bdi->wb.dwork, timeout);
- spin_unlock_bh(&bdi->wb_lock);
+ spin_lock_bh(&wb->work_lock);
+ if (test_bit(WB_registered, &wb->state))
+ queue_delayed_work(bdi_wq, &wb->dwork, timeout);
+ spin_unlock_bh(&wb->work_lock);
}
/*
@@ -335,28 +335,24 @@ EXPORT_SYMBOL(bdi_register_dev);
/*
* Remove bdi from the global list and shutdown any threads we have running
*/
-static void bdi_wb_shutdown(struct backing_dev_info *bdi)
+static void wb_shutdown(struct bdi_writeback *wb)
{
/* Make sure nobody queues further work */
- spin_lock_bh(&bdi->wb_lock);
- if (!test_and_clear_bit(WB_registered, &bdi->wb.state)) {
- spin_unlock_bh(&bdi->wb_lock);
+ spin_lock_bh(&wb->work_lock);
+ if (!test_and_clear_bit(WB_registered, &wb->state)) {
+ spin_unlock_bh(&wb->work_lock);
return;
}
- spin_unlock_bh(&bdi->wb_lock);
+ spin_unlock_bh(&wb->work_lock);
/*
- * Make sure nobody finds us on the bdi_list anymore
+ * Drain work list and shutdown the delayed_work. !WB_registered
+ * tells wb_workfn() that @wb is dying and its work_list needs to
+ * be drained no matter what.
*/
- bdi_remove_from_list(bdi);
-
- /*
- * Drain work list and shutdown the delayed_work. At this point,
- * @bdi->bdi_list is empty telling bdi_Writeback_workfn() that @bdi
- * is dying and its work_list needs to be drained no matter what.
- */
- mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
- flush_delayed_work(&bdi->wb.dwork);
+ mod_delayed_work(bdi_wq, &wb->dwork, 0);
+ flush_delayed_work(&wb->dwork);
+ WARN_ON(!list_empty(&wb->work_list));
}
/*
@@ -381,7 +377,7 @@ EXPORT_SYMBOL(bdi_unregister);
*/
#define INIT_BW (100 << (20 - PAGE_SHIFT))
-static int bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
+static int wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
{
int i, err;
@@ -394,7 +390,6 @@ static int bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
INIT_LIST_HEAD(&wb->b_more_io);
INIT_LIST_HEAD(&wb->b_dirty_time);
spin_lock_init(&wb->list_lock);
- INIT_DELAYED_WORK(&wb->dwork, bdi_writeback_workfn);
wb->bw_time_stamp = jiffies;
wb->balanced_dirty_ratelimit = INIT_BW;
@@ -402,6 +397,10 @@ static int bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
wb->write_bandwidth = INIT_BW;
wb->avg_write_bandwidth = INIT_BW;
+ spin_lock_init(&wb->work_lock);
+ INIT_LIST_HEAD(&wb->work_list);
+ INIT_DELAYED_WORK(&wb->dwork, wb_workfn);
+
err = fprop_local_init_percpu(&wb->completions, GFP_KERNEL);
if (err)
return err;
@@ -419,7 +418,7 @@ static int bdi_wb_init(struct bdi_writeback *wb, struct backing_dev_info *bdi)
return 0;
}
-static void bdi_wb_exit(struct bdi_writeback *wb)
+static void wb_exit(struct bdi_writeback *wb)
{
int i;
@@ -440,11 +439,9 @@ int bdi_init(struct backing_dev_info *bdi)
bdi->min_ratio = 0;
bdi->max_ratio = 100;
bdi->max_prop_frac = FPROP_FRAC_BASE;
- spin_lock_init(&bdi->wb_lock);
INIT_LIST_HEAD(&bdi->bdi_list);
- INIT_LIST_HEAD(&bdi->work_list);
- err = bdi_wb_init(&bdi->wb, bdi);
+ err = wb_init(&bdi->wb, bdi);
if (err)
return err;
@@ -454,9 +451,9 @@ EXPORT_SYMBOL(bdi_init);
void bdi_destroy(struct backing_dev_info *bdi)
{
- bdi_wb_shutdown(bdi);
-
- WARN_ON(!list_empty(&bdi->work_list));
+ /* make sure nobody finds us on the bdi_list anymore */
+ bdi_remove_from_list(bdi);
+ wb_shutdown(&bdi->wb);
if (bdi->dev) {
bdi_debug_unregister(bdi);
@@ -464,7 +461,7 @@ void bdi_destroy(struct backing_dev_info *bdi)
bdi->dev = NULL;
}
- bdi_wb_exit(&bdi->wb);
+ wb_exit(&bdi->wb);
}
EXPORT_SYMBOL(bdi_destroy);