In the case we trigger dlm_free_rsb() that does a call_rcu() and the
responding kfree() of res_lvbptr and a kmem_cache_free() of the rsb
pointer we need to wait until this pending operation is done before
calling kmem_cache_destroy(). We doing that by using rcu_barrier() that
waits until all pending call_rcu() are done. This avoids that
kmem_cache_destroy() complains about active objects around that are not
being freed yet by call_rcu().

There is currently more discussions about to make this behaviour better,
see:

https://lore.kernel.org/netdev/20240609082726.32742-1-Julia.Lawall@inria.fr/

However this is only for call_rcu() if the callback calls
kmem_cache_destroy() only to replace it by kfree_rcu() call which has
currently some issue. This isn't our case because we also free the
res_lvbptr if being set.

For our case, to avoid the above race rcu_barrier() should be used before
calling kmem_cache_destroy() to be sure that there are no active objects
around. This is exactly what net/batman-adv is also doing before calling their
kmem_cache_destroy() in module unloading.

Fixes: 01fdeca1cc2d ("dlm: use rcu to avoid an extra rsb struct lookup")
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

The DLM rcom handling has a check that all exflags are the same for the
whole lockspace membership nodes. There are some flags that requires
such handling, however DLM_LSFL_SOFTIRQ does not require this handling
and it should be backwards compatibility with other lockspaces that does
not set this flag.

Fixes: f328a26eeb53 ("dlm: introduce DLM_LSFL_SOFTIRQ_SAFE")
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

The last use of 'dlm_processed_nodes' was removed in
commit 1696c75f1864 ("fs: dlm: add send ack threshold and append acks to
msgs").

Remove it.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: David Teigland <teigland@redhat.com>

When a lockspace user allows it, run callback functions directly from
softirq context, instead of queueing callbacks to be run from the
dlm_callback workqueue context.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

Introduce a new external lockspace flag DLM_LSFL_SOFTIRQ_SAFE.  A
lockspace user will set this flag if it can handle dlm running the
callback functions from softirq context.  When not set, dlm will
continue to run callback functions from the dlm_callback workqueue.
The new lockspace flag cannot be used for user space lockspaces, so
a uapi placeholder definition is used for the new flag value.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

The existing external lockspace flag DLM_LSFL_FS is now also
saved as an internal flag LSFL_FS, so it can be checked from
other code locations which want to know if a lockspace is
used from the kernel or user space.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

Use rcu to free rsb structs, and hold the rcu read lock
while looking up rsb structs.  This allows us to avoid an
extra hash table lookup for an rsb.  A new rsb flag HASHED
is added which is set while the rsb is in the hash table.
This flag is checked in place of repeating the hash table
lookup.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>

Remove a few calls to add_scan() and del_scan() in cases where
the rsb is a dir record, so the rsb should never be placed on
the scan list at all.  Add WARN_ON to catch cases where this
is done.

Signed-off-by: David Teigland <teigland@redhat.com>

The old terminology of "toss" and "keep" is no longer an
accurate description of the rsb states and lists, so change
the names to "inactive" and "active".  The old names had
also been copied into the scanning code, which is changed
back to use the "scan" name.

- "active" rsb structs have lkb's attached, and are ref counted.
- "inactive" rsb structs have no lkb's attached, are not ref counted.
- "scan" list is for rsb's that can be freed after a timeout period.
- "slow" lists are for infrequent iterations through active or
   inactive rsb structs.
- inactive rsb structs that are directory records will not be put
  on the scan list, since they are not freed based on timeouts.
- inactive rsb structs that are not directory records will be
  put on the scan list to be freed, since they are not longer needed.

Signed-off-by: David Teigland <teigland@redhat.com>

According to kdoc idr is deprecated and xarrays should be used nowadays.
This patch is moving the recover idr implementation to xarray
datastructure.

Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>