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 incrementing dev_stats_ccnt in
btrfs_dev_replace_finishing() when replace is succeeded and this will
update the values.

Signed-off-by: Misono Tomohiro <misono.tomohiro@jp.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index 5a72f9933e58..dec01970d8c5 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -672,6 +672,12 @@ 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
          * source device is not part of the filesystem anymore and its 1st