Currently, it's not really 'safe' in ihandle to issue an IH_OPEN
against an IHandle_t when an IH_REALLYCLOSE is running at the same
time. The reasons for this are explained a bit in ticket 131530 and
related commits, but briefly:
Say IH_OPEN runs, and drops IH_LOCK to open a new fd on disk. Then
IH_REALLYCLOSE runs and closes all fds, or marks them as needing
close. The running IH_OPEN then acquires IH_LOCK again and puts the
newly-opened fd onto the per-IH list of fds. We now have an fd that
effectively "survives" across the IH_REALLYCLOSE; effectively
IH_REALLYCLOSE did not close all fds for the ih.
This is possibly fixable by maintaining some extra information in
IHandle_t's, but this is only a problem if we allow IH_OPEN calls to
happen simultaneously with IH_REALLYCLOSE calls. Ever since
ih_sync_thread was removed (or changed to not call IH_OPEN), there
should be no cases where this is possible. All instances of
IH_REALLYCLOSE happen during error recovery for a newly-created file,
or happen under a per-vnode write lock, or for volume metadata files
only happens when the ref count for a volume drops to zero when we're
offlining the volume.
So, do not bother trying to fix this, since doing so is currently a
waste of time and the resulting complexity could introduce bugs. But
in case someone ever tries to do something resulting in IH_OPEN calls
executing outside the normal threads of execution, add a comment
around the IH_REALLYCLOSE explanations to try and briefly explain that
this cannot currently be done.
projects / packages / o / openafs.git / commit