A while ago David reported a bug in zoned btrfs' relocation code. The bug is
triggered because relocation on a zoned filesystem does not preallocate the
extents it copies and a writeback process running in parallel can cause a
split of the written extent. But splitting extents is currently not allowed on
relocation as it assumes a one to one copy of the relocated extents.

This causes transaction aborts and the fielssytem switching to read-only in
order to prevent further damage.

The first patch in this series is just a preparation to avoid overly long
lines in follow up patches. Patch number two adds a dedicated block group for
relocation on a zoned filesystem. Patch three switches relocation from
REQ_OP_ZONE_APPEND to regular REQ_OP_WRITE, four prepares an ASSERT()ion that
we can enter the nocow path on a  zoned filesystem under very special
circumstances and the fifth patch then switches the relocation code for a
zoned filesystem to using the same code path as we use on a non zoned
filesystem. As the changes before have made the prerequisites to do so. The
last patch in this series is jsut a simple rename of a function whose name we
have twice in the btrfs codebase but with a different purpose in different
files.

Johannes Thumshirn (6):
  btrfs: introduce btrfs_is_data_reloc_root
  btrfs: zoned: add a dedicated data relocation block group
  btrfs: zoned: use regular writes for relocation
  btrfs: check for relocation inodes on zoned btrfs in should_nocow
  btrfs: zoned: allow preallocation for relocation inodes
  btrfs: rename setup_extent_mapping in relocation code

 fs/btrfs/block-group.c |  1 +
 fs/btrfs/ctree.h       |  7 ++++++
 fs/btrfs/disk-io.c     |  3 ++-
 fs/btrfs/extent-tree.c | 52 +++++++++++++++++++++++++++++++++++++++---
 fs/btrfs/inode.c       | 22 ++++++++----------
 fs/btrfs/relocation.c  | 43 +++++-----------------------------
 fs/btrfs/zoned.c       |  3 +++
 fs/btrfs/zoned.h       |  9 ++++++++
 8 files changed, 87 insertions(+), 53 deletions(-)

-- 
2.32.0