This fixes a problem with ganesha+cephfs and delegations: caps_issued_mask is a function that we call to see if we have all of the caps provided in a mask. Usually this ignores caps that have been revoked by the MDS but that have not yet been released by the client. These caps are still valid though -- nothing else can use them until they've been released. These codepaths call caps_issued_mask only in order to determine whether the client holds enough caps to trust cached attributes. They don't take new references to the caps, so it should be safe to use the "implemented" capset in these functions. This helps break a deadlock that can occur when the client holds a delegation that has been recalled, but needs to satisfy a getattr request before releasing it. The PR has a testcase in it that tests this (LibCephFS.RecalledGetattr).
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHBA-2018:2375