• S
    ceph: fix iterate_caps removal race · 7c1332b8
    Sage Weil 提交于
    We need to be able to iterate over all caps on a session with a
    possibly slow callback on each cap.  To allow this, we used to
    prevent cap reordering while we were iterating.  However, we were
    not safe from races with removal: removing the 'next' cap would
    make the next pointer from list_for_each_entry_safe be invalid,
    and cause a lock up or similar badness.
    
    Instead, we keep an iterator pointer in the session pointing to
    the current cap.  As before, we avoid reordering.  For removal,
    if the cap isn't the current cap we are iterating over, we are
    fine.  If it is, we clear cap->ci (to mark the cap as pending
    removal) but leave it in the session list.  In iterate_caps, we
    can safely finish removal and get the next cap pointer.
    
    While we're at it, clean up put_cap to not take a cap reservation
    context, as it was never used.
    Signed-off-by: NSage Weil <sage@newdream.net>
    7c1332b8
caps.c 77.8 KB