[PATCH 05/10] writeback: move lingering dirty IO lists transfer from bdi_destroy() to wb_exit()

From: Tejun Heo
Date: Tue Nov 18 2014 - 03:39:52 EST


If a bdi still has dirty IOs on destruction, bdi_destroy() transfers
them to the default bdi; however, dirty IO lists belong to wb
(bdi_writeback) not bdi (backing_dev_info) and after the recent
changes we now have wb_exit() which handles destruction of a wb. Move
the transfer logic to wb_exit().

This patch is pure reorganization.

Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx>
---
mm/backing-dev.c | 48 ++++++++++++++++++++++++------------------------
1 file changed, 24 insertions(+), 24 deletions(-)

diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 4904456..18a4c32 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -456,6 +456,30 @@ static void wb_exit(struct bdi_writeback *wb)

WARN_ON(delayed_work_pending(&wb->dwork));

+ /*
+ * Splice our entries to the default_backing_dev_info. This
+ * condition shouldn't happen. @wb must be empty at this point and
+ * dirty inodes on it might cause other issues. This workaround is
+ * added by ce5f8e779519 ("writeback: splice dirty inode entries to
+ * default bdi on bdi_destroy()") without root-causing the issue.
+ *
+ * http://lkml.kernel.org/g/1253038617-30204-11-git-send-email-jens.axboe@xxxxxxxxxx
+ * http://thread.gmane.org/gmane.linux.file-systems/35341/focus=35350
+ *
+ * We should probably add WARN_ON() to find out whether it still
+ * happens and track it down if so.
+ */
+ if (wb_has_dirty_io(wb)) {
+ struct bdi_writeback *dst = &default_backing_dev_info.wb;
+
+ bdi_lock_two(wb, dst);
+ list_splice(&wb->b_dirty, &dst->b_dirty);
+ list_splice(&wb->b_io, &dst->b_io);
+ list_splice(&wb->b_more_io, &dst->b_more_io);
+ spin_unlock(&wb->list_lock);
+ spin_unlock(&dst->list_lock);
+ }
+
for (i = 0; i < NR_WB_STAT_ITEMS; i++)
percpu_counter_destroy(&wb->stat[i]);

@@ -483,30 +507,6 @@ EXPORT_SYMBOL(bdi_init);

void bdi_destroy(struct backing_dev_info *bdi)
{
- /*
- * Splice our entries to the default_backing_dev_info. This
- * condition shouldn't happen. @wb must be empty at this point and
- * dirty inodes on it might cause other issues. This workaround is
- * added by ce5f8e779519 ("writeback: splice dirty inode entries to
- * default bdi on bdi_destroy()") without root-causing the issue.
- *
- * http://lkml.kernel.org/g/1253038617-30204-11-git-send-email-jens.axboe@xxxxxxxxxx
- * http://thread.gmane.org/gmane.linux.file-systems/35341/focus=35350
- *
- * We should probably add WARN_ON() to find out whether it still
- * happens and track it down if so.
- */
- if (bdi_has_dirty_io(bdi)) {
- struct bdi_writeback *dst = &default_backing_dev_info.wb;
-
- bdi_lock_two(&bdi->wb, dst);
- list_splice(&bdi->wb.b_dirty, &dst->b_dirty);
- list_splice(&bdi->wb.b_io, &dst->b_io);
- list_splice(&bdi->wb.b_more_io, &dst->b_more_io);
- spin_unlock(&bdi->wb.list_lock);
- spin_unlock(&dst->list_lock);
- }
-
bdi_unregister(bdi);
wb_exit(&bdi->wb);
}
--
1.9.3

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