afr: thin-arbiter 2 domain locking and in-memory state

2 domain locking + xattrop for write-txn failures:
--------------------------------------------------
- A post-op wound on TA takes AFR_TA_DOM_NOTIFY range lock and
AFR_TA_DOM_MODIFY full lock, does xattrop on TA and releases
AFR_TA_DOM_MODIFY lock and stores in-memory which brick is bad.

- All further write txn failures are handled based on this in-memory
value without querying the TA.

- When shd heals the files, it does so by requesting full lock on
AFR_TA_DOM_NOTIFY domain. Client uses this as a cue (via upcall),
releases AFR_TA_DOM_NOTIFY range lock and invalidates its in-memory
notion of which brick is bad. The next write txn failure is wound on TA
to again update the in-memory state.

- Any incomplete write txns before the AFR_TA_DOM_NOTIFY upcall release
request is got is completed before the lock is released.

- Any write txns got after the release request are maintained in a ta_waitq.

- After the release is complete, the ta_waitq elements are spliced to a
separate queue which is then processed one by one.

- For fops that come in parallel when the in-memory bad brick is still
unknown, only one is wound to TA on wire. The other ones are maintained
in a ta_onwireq which is then processed after we get the response from
TA.

Change-Id: I32c7b61a61776663601ab0040e2f0767eca1fd64
updates: bz#1579788
Signed-off-by: Ravishankar N <ravishankar@redhat.com>
Signed-off-by: Ashish Pandey <aspandey@redhat.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/xlators/cluster/afr/src/afr-transaction.h b/xlators/cluster/afr/src/afr-transaction.h
index fff8c65e976..35a922544bc 100644
--- a/xlators/cluster/afr/src/afr-transaction.h
+++ b/xlators/cluster/afr/src/afr-transaction.h
@@ -67,4 +67,9 @@ afr_lock(call_frame_t *frame, xlator_t *this);
 void
 afr_delayed_changelog_wake_up_cbk(void *data);
 
+int
+afr_release_notify_lock_for_ta(void *opaque);
+
+int
+afr_ta_lock_release_done(int ret, call_frame_t *ta_frame, void *opaque);
 #endif /* __TRANSACTION_H__ */