README

  updates.

diff --git a/README b/README
index 94f1afe4b7752a31f8474fd70fa2d2dca9ed2bfc..74461efb7ce3d461c24263dd7f9648734f6c9127 100644 (file)
--- a/README
+++ b/README
@@ -1822,4 +1822,49 @@ FIXME when I "rm [b-z]*" it waits for writeback on something???
   bothers to remove them.  I guess it should...
   OK, lots of InoIdx block have gone now with their DATA blocks.
 
+  So, remaining blocks are pinned to their phase with lots of Credits,
+    have not pincnt, mostly have physaddr==0.
+   It is just the stray refcnt that keeps them there..
+   inums are 40, 56, 62-73, 275-278, 280
+    40 is f22
+    56 is first adir
+    63-69 are directories 2/3/4/5/6/7/8/9
+    70-73 are looooong symlinks
+    275 is cfile
+    276 is dfile - same as cfile but truncated.
+      Then some nbfile-X that were big enough.
+
+   So: what do they have in common:
+     Several only use the in-inode data block, but
+       probably not all
+
+    Can it be that it is refcounted on the Leaf list, and so
+    cannot get off??  Yes, I think so!
+    We only unpin things that have a zero refcount.
+
+    So: what to do?
+      checkpoint takes it off the list, then flips the phase and puts it
+      on the other list with refile.  During that time it has a refcount
+      it doesn't lose the pinning.
+      Do we want to:
+        1/ Not have it on the list despite being pinned.
+       2/ Drop the PIN despite the refcnt.
+        3/ have refile do the phase_flip so it has a chance to
+           notice the refcount has hit zero.
+
+      2 isn't really an option.  We need PIN to persist whenver we have
+       a reference.  We could possibly use PinPending for index blocks too,
+       but that would require a lot of thinking.
+      1 requires another criterea for being on the list.  I suspect that would
+       get messy fast.
+      3 we used to do I think... But refile is in a big lock, and we
+        cannot really do a phase_flip under that.. and phase flip calls
+         refile anyway so we would get recursion.
+      So:4 - get lafs_phase_flip to notice and de-pin rather than flip.
+
+      FIXME use kzalloc where appropriate.
+
+      FIXME Maybe test refcnt-!listempty in refile and de-pin if that is zero.
+
+