Hi, I send this rfc patch series to show a (for me) usable use-case for the DLM net-namespace functionality that is currently pending, see [0]. This patch-series introduce the DLM verifier to check on DLM correctness on any workload running on DLM with net-namespace feature. E.g. on gfs2 you can just run some filesystem benchmark tests and see if DLM works as aspected.
This comes very useful when DLM recovery kicks in e.g. when nodes leaving the lockspace due e.g. fencing and recovery solves lock dependencies transparently from the user. However there is no "fake fencing switch" yet for DLM net-namespaces, but might be an idea for future functionality. There could be bugs in the verifier, that I don't care if they exists... We need to check whats happening when the verifier complains but so far everything looks fine. It just an issue if the verifier doesn't say anything but a small bug introduced in DLM and the verifier will complain a lot. There might be still improvements in the DLM verifier. I needed to change a little bit the python scripts to generate the code but I did not add them here to this patch series. Also checkpatch complains about some things in the verifier code but I oriented myself mostly to the other existing verifiers. There is a printout of all holders if those violates the DLM compatible locking states. I might improve them when I actually try to figure out an existing problem, but for now this printout is very minimal. I mainly do this work because I prepare more changes in the DLM recovery code in future to scale with lockspaces with a lot of members that we can easily try out with the net-namespace functionality. I cc here the rcu people, may they also get some ideas to check on lock correctness using tracing kernel verifier subsystem. - Alex [0] https://lore.kernel.org/gfs2/20240814143414.1877505-1-aahri...@redhat.com/ Alexander Aring (7): dlm: fix possible lkb_resource null dereference dlm: fix swapped args sb_flags vs sb_status dlm: make add_to_waiters() that is can't fail dlm: add our_nodeid to tracepoints dlm: add lkb rv mode to ast tracepoint dlm: add more tracepoints for DLM kernel verifier rv: add dlm compatible lock state kernel verifier Documentation/trace/rv/monitor_dlm.rst | 77 +++++ fs/dlm/ast.c | 30 +- fs/dlm/dlm_internal.h | 3 + fs/dlm/lock.c | 64 ++-- fs/dlm/lockspace.c | 4 + fs/dlm/user.c | 9 +- include/trace/events/dlm.h | 121 ++++++- include/trace/events/rv.h | 9 + kernel/trace/rv/Kconfig | 18 + kernel/trace/rv/Makefile | 1 + kernel/trace/rv/monitors/dlm/dlm.c | 445 +++++++++++++++++++++++++ kernel/trace/rv/monitors/dlm/dlm.h | 38 +++ kernel/trace/rv/monitors/dlm/dlm_da.h | 143 ++++++++ tools/verification/models/dlm.dot | 14 + 14 files changed, 907 insertions(+), 69 deletions(-) create mode 100644 Documentation/trace/rv/monitor_dlm.rst create mode 100644 kernel/trace/rv/monitors/dlm/dlm.c create mode 100644 kernel/trace/rv/monitors/dlm/dlm.h create mode 100644 kernel/trace/rv/monitors/dlm/dlm_da.h create mode 100644 tools/verification/models/dlm.dot -- 2.43.0
