From 488bc2a2d21e5faf14f9f695bb592ae9dd0e7465 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Fri, 18 Dec 2020 14:24:26 -0500 Subject: [PATCH] btrfs: run delayed refs less often in commit_cowonly_roots We love running delayed refs in commit_cowonly_roots, but it is a bit excessive. I was seeing cases of running 3 or 4 refs a few times in a row during this time. Instead simply: - update all of the roots first - then run delayed refs - then handle the empty block groups case - and then if we have any more dirty roots do the whole thing again This allows us to be much more efficient with our delayed ref running, as we can batch a few more operations at once. Reviewed-by: Nikolay Borisov Signed-off-by: Josef Bacik Signed-off-by: David Sterba --- fs/btrfs/transaction.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c index 02592c6ce755..b83e8ae38cfc 100644 --- a/fs/btrfs/transaction.c +++ b/fs/btrfs/transaction.c @@ -1226,10 +1226,6 @@ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans) btrfs_tree_unlock(eb); free_extent_buffer(eb); - if (ret) - return ret; - - ret = btrfs_run_delayed_refs(trans, (unsigned long)-1); if (ret) return ret; @@ -1247,10 +1243,6 @@ static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans) if (ret) return ret; - /* run_qgroups might have added some more refs */ - ret = btrfs_run_delayed_refs(trans, (unsigned long)-1); - if (ret) - return ret; again: while (!list_empty(&fs_info->dirty_cowonly_roots)) { struct btrfs_root *root; @@ -1265,15 +1257,24 @@ again: ret = update_cowonly_root(trans, root); if (ret) return ret; - ret = btrfs_run_delayed_refs(trans, (unsigned long)-1); - if (ret) - return ret; } + /* Now flush any delayed refs generated by updating all of the roots */ + ret = btrfs_run_delayed_refs(trans, (unsigned long)-1); + if (ret) + return ret; + while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) { ret = btrfs_write_dirty_block_groups(trans); if (ret) return ret; + + /* + * We're writing the dirty block groups, which could generate + * delayed refs, which could generate more dirty block groups, + * so we want to keep this flushing in this loop to make sure + * everything gets run. + */ ret = btrfs_run_delayed_refs(trans, (unsigned long)-1); if (ret) return ret; -- 2.34.1