windows-scache-recycle-20060603

windows-scache-recycle-20060603

A deadlock was detected when performing "fs flushall" if the file
server reports VNOVNODE.   The scp->createBufferLock is already
held by the current thread and there is no mechanism to propagate
the knowledge.  Therefore, an alternate mechanism for clearing the
cache must be developed.  A new function cm_RecycleSCache(scp,flags)
has been extracted from cm_GetNewSCache().  This function performs
the task of recycling an cm_scache_t object.  When called from
cm_GetNewSCache() with no flags the expectation is that there are
no associated buffers that are queued to be read or written.  When
called from cm_Analyze() with the CM_SCACHE_RECYCLEFLAG_DESTROY_BUFFERS
flag, any queued buffers will be de-queued and marked as if the operations
were performed so the data can be discarded.

This patch also addresses the following issues:

* CM_ERROR codes were logged as "unknown" by cm_Analyze.

* In response to VNOVNODE, the parent is only discarded if the current
  cm_scache_t is not a directory.

* In the Ioctl FlushFile and FlushVolume functions, there were no
  checks to protect against flushing the Freelance SCache entries.

* In FlushFile, the wrong cm_scache_t object was being released.

* In cm_GetNewSCache, do not allow Freelance SCache entries to be
  recycled.  Choose a new entry if cm_RecycleSCache fails.