Ceph » CephFS

inode auth                 dirfrag auth
auth                       (inode replica)

v1 0                       (v1 10)/(v1 0) (dirty)  MIX

...gather...               SYNC or LOCK
  sum
v2 10 
...scatter...

                           if !frozen, journal dirfrag, set accounted_fragstat = fragstat, and version
                           (v2 10)/(v2 10)   
                           MIX

                           MIX_STALE
                           (v1 10)/(v1 10)

...gather...

crash...replay

 rejoin needs to put us in MIX_STALE if our fragstat versions are older than the inode's

...gather...
  sum

r -> a REQNUDGE
a -> *
* -> a
a -> j
j -> a
a -> * SYNC
r -> j (async)
r -> a REQSCATTER
a -> * AC_MIX   stop reading
* -> a MIX_ACK
a -> * AC_MIX2  ok now you can write

r -> a REQTEMPSYNC
a -> *
* -> a
a -> j
j -> a  auth now TSYN
a -> * AC_MIX  ok now you can write
r -> j (async)

r drain all requests and locks
r unwind

a r1 r2

a -> r1,r2 SYNC
r1 is pinned,doesn't reply
r2 -> a SYNC_ACK without tree (not auth yet)
r1 sends frozen subtree to r2
unfreeze
unscatter_pin
r1 -> a (not including tree, not auth anymore)
a finishes gather, updates inode.