[PATCH v2 0/2] btrfs: add sysfs interface for qgroup

[Qu Wenruo <wqu@suse.com>]

This patchset will add the following sysfs interfaces for qgroup:

  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/reference
  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/exclusive
  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/max_reference
  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/max_exclusive
  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/limit_flags
   ^^^ Above are already in "btrfs qgroup show" command output ^^^
  
  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/rsv_data
  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/rsv_meta_pertrans
  /sys/fs/btrfs/<UUID>/qgroups/<qgroup_id>/rsv_meta_prealloc

These interfaces are mostly for debug purpose, to give us a clear view
of which part is leaking.

Changelog:
v2:
- Add a new patch to change the return value type of
  btrfs_qgroup_level()

- Fix the wrong btrfs_sysfs_add_one_qgroup() call timming
  That function needs to allocate memory, thus can't be called in
  add_qgroup_rb() where some call sites are holding a spin lock.
  Delay btrfs_sysfs_add_one_qgroup() after add_qgroup_rb() until the
  spin lock is released.

- Skip qgroup sysfs interface for qgroup selftest
  This makes no sense for selftest to initialize the sysfs interface
  and since we don't initialize fs_devices->kobj either, it's not
  possible to utilize the sysfs interface in selftest.

- Use proper helpers for qgroup BTRFS_ATTRs

- Use more human-readable names in qgroup sysfs entries

- Remove the unneeded completion for qgroup


Qu Wenruo (2):
  btrfs: use __u16 for the return value of btrfs_qgroup_level()
  btrfs: qgroup: add sysfs interface for debug

 fs/btrfs/ctree.h                |   1 +
 fs/btrfs/qgroup.c               |  46 +++++++---
 fs/btrfs/qgroup.h               |  11 +++
 fs/btrfs/sysfs.c                | 151 ++++++++++++++++++++++++++++++++
 fs/btrfs/sysfs.h                |   6 ++
 include/uapi/linux/btrfs_tree.h |   4 +-
 6 files changed, 207 insertions(+), 12 deletions(-)

-- 
2.27.0