btrfs: replace: Reset on-disk dev stats value after replace

on-disk devs stats value is updated in btrfs_run_dev_stats(), which is called during commit transaction, if device->dev_stats_ccnt is not zero.

Since current replace operation does not touch dev_stats_ccnt, on-disk dev stats value is not updated. Therefore "btrfs device stats" may return old device's value after umount/mount
(Example: See "btrfs ins dump-t -t DEV $DEV" after btrfs/100 finish).

Fix this by just increment dev_stats_ccnt in btrfs_dev_replace_finishing() when replace is succeeded.

---
 fs/btrfs/dev-replace.c | 6 ++++++
 1 file changed, 6 insertions(+)

index e2ba0419297a..d20b244623f2 100644
@@ -676,6 +676,12 @@ static int btrfs_dev_replace_finishing(struct btrfs_fs_info *fs_info,
 
 	btrfs_rm_dev_replace_unblocked(fs_info);
 
+	/*
+	 * Increment dev_stats_ccnt so that btrfs_run_dev_stats() will
+	 * update on-disk dev stats value during commit transaction
+	 */
+	atomic_inc(&tgt_device->dev_stats_ccnt);
+
 	/*
 	 * this is again a consistent state where no dev_replace procedure
 	 * is running, the target device is part of the filesystem, the

2.14.4

In such cases it's good to have a snippet of the output, so it's possible to match the output and check if we see the same thing.

Otherwise looks ok, thanks.