[PATCH 0/2] btrfs: qgroup: mark qgroup inconsistent for more

[Qu Wenruo <wqu@suse.com>]

Commit 011b46c30476 ("btrfs: skip subtree scan if it's too high to avoid
low stall in btrfs_commit_transaction()") covers the most common case
that can cause a long qgroup stall, where a large subtree is rescanned
when dropping a snapshot.

But there are more corner cases for the same long qgroup stall:

- A qgroup rescan is queued immediately after marking inconsistent
  The new rescan will immediately revert the NO_ACCOUNTING flag, thus
  still results long qgroup stalls.

- A subvolume with no shared subtree
  This can still queue a lot of workload into the current transaction.

This series covers both less-common cases.

Qu Wenruo (2):
  btrfs: reject new qgroup rescan during subvolume dropping
  btrfs: avoid long stall when dropping a non-shared large subvolume

 fs/btrfs/disk-io.c     |  4 ++++
 fs/btrfs/extent-tree.c | 11 +++++++++++
 fs/btrfs/qgroup.c      | 29 ++++++++++++++++++++++++++++-
 fs/btrfs/qgroup.h      | 15 +++++++++++++++
 4 files changed, 58 insertions(+), 1 deletion(-)

-- 
2.55.0