[PATCH v6 0/2] ocfs2: give ocfs2 the ability to reclaim suballocator free bg

[Heming Zhao <heming.zhao@suse.com>]

v6:

patch [2/2]:
- based on Joseph's review comments, restored code indent & removed useless parentheses.

v5:

patch [2/2]: change -EINVAL to -ESTALE and adjust the callers error handling.

pass xfstest case: ./check -T -b -s ocfs2 generic/426

v4:

Most of the changes involve revising comments. For the code itself, there are
function renames and parameter usage adjustments, but no changes to the code
logic.

For patch [1/2]:
- Based on Joseph's v3 review comments:
  1. Modify the caller to initialize the ocfs2_read_hint_group_descriptor()
     input parameter '*released'.
  2. Rename the _reclaim_to_main_bm() to _ocfs2_reclaim_suballoc_to_main()
  3. Change the text "not empty rec" to "non empty rec"

- Revise the comments preceding the function _ocfs2_reclaim_suballoc_to_main().

- For the question: "How to distinguish the release case or a bug?"
  I write a comment before ocfs2_read_hint_group_descriptor().

- Revise the commit log to make it clearer.

For patch [2/2]:
- Revise the commit log to make it clearer.

Remove the v3 patch: "ocfs2: adjust spinlock_t ip_lock protection scope"
- Reason: This patch belongs to a different topic/job and should be
          handled separately.

Run test caese:

xfstest: ./check -g quick -T -b -s ocfs2 -e generic/032 -e generic/076 \
-e generic/081 -e generic/266 -e generic/272 -e generic/281 \
-e generic/331 -e generic/338 -e generic/347 -e generic/361 \
-e generic/479 -e generic/480 -e generic/628 -e generic/629 \
-e generic/648 -e generic/650

with/without the patch set, *Failures* are same:
generic/003 generic/007 generic/228 generic/322 generic/329 generic/376
generic/383 generic/384 generic/385 generic/386 generic/420 generic/424
generic/448 generic/449 generic/510 generic/513 generic/537 generic/552
generic/563 generic/578 generic/594 generic/607 generic/620 generic/630
generic/741 generic/755

For the ocfs2-test, it seems that open-mpi4 does not work correctly in my test
environment (OpenSUSE TumbleWeed). Therefore, I only ran the tests in single-node
mode. The results were the same between the patched code and the unpatched code.

ocfs2-test cases:
```
$ single_run-WIP.sh -f 1 -k /usr/local/ocfs2-test/tmp/linux-2.6.39.tar.gz -l \
/usr/local/ocfs2-test/log -m /mnt/ocfs2 -d /dev/vde -b 4096 -c 32768 -s pcmk \
-n hacluster -t create_and_open,directaio,fillverifyholes,renamewriterace,\
aiostress,filesizelimits,mmaptruncate,buildkernel,splice,sendfile,reserve_space,\
mmap,inline,xattr,reflink,mkfs,tunefs,backup_super

$ discontig_runner.sh -f 1 -d /dev/vde -b 4096 -c 32768 -s pcmk -n hacluster /mnt/ocfs2
```

v3:

For patch [1/3]:
- Factor out the reclaim code into a new function '_reclaim_to_main_bm'.
- The function ocfs2_read_hint_group_descriptor doesn't return -EIDRM
  when the group descriptor is invalid. The new code logic returns 0,
  and the input parameter '*released' is set to 1.

For patch [2/3]:
- Modify the code to follow the new logic of ocfs2_read_hint_group_descriptor
  as introduced in patch [1/3].

For patch [3/3]:
- No new changes.

v3 patch has passed the xfstests:
./check -g quick -T -b -s ocfs2 -e generic/032 -e generic/076 \
-e generic/081 -e generic/266 -e generic/272 -e generic/281 \
-e generic/331 -e generic/338 -e generic/347 -e generic/361 \
-e generic/479 -e generic/480 -e generic/628 -e generic/629 \
-e generic/648 -e generic/650

v2:

Create 2 new patches:
- ocfs2: detect released suballocator bg for fh_to_[dentry|parent]
- ocfs2: adjust spinlock_t ip_lock protection scope

In ocfs2_read_hint_group_descriptor()
- bypass the validation of GD when the BH is already managed by jbd2.

In _ocfs2_free_suballoc_bits()
- Move up the position of the vars 'idx' & 'rec'.
- Move up the position of the ocfs2_journal_dirty.
- Use le[16|32]_to_cpu() to access cl/fe/rec vars.
- Add error handling for calling ocfs2_extend_trans().
- adjust spin_lock ->ip_lock protection scope.
- Follow Glass's review comments, add 'comment' & 'else-break' for the
  'for-loop'.

v1:

Only create patch:
- ocfs2: give ocfs2 the ability to reclaim suballoc free bg

Heming Zhao (2):
  ocfs2: give ocfs2 the ability to reclaim suballocator free bg
  ocfs2: detect released suballocator BG for fh_to_[dentry|parent]

 fs/ocfs2/export.c   |   6 +-
 fs/ocfs2/suballoc.c | 334 +++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 320 insertions(+), 20 deletions(-)

-- 
2.43.0