reclaim: export address of the OSV reclaimer

ZFS will perform some checks to determine if the current calling "process"
is the reclaimer. Export the address of the reclaimer thread so that test
can work.

Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

bsd/porting/kthread.h

@@ -30,6 +30,9 @@ __END_DECLS
 
 #define curproc (get_curproc())
 
+extern unsigned char *osv_reclaimer_thread;
+#define pageproc ((struct proc *)osv_reclaimer_thread)
+
 #endif
 
 #endif

core/mempool.cc

@@ -40,6 +40,7 @@ TRACEPOINT(trace_memory_huge_failure, "page ranges=%d", unsigned long);
 TRACEPOINT(trace_memory_reclaim, "shrinker %s, target=%d, delta=%d", const char *, long, long);
 
 bool smp_allocator = false;
+unsigned char *osv_reclaimer_thread;
 
 namespace memory {
 
@@ -615,6 +616,7 @@ reclaimer::reclaimer()
     // std::thread is implemented ontop of pthreads, so it is fine
     std::thread tmp([&] {
         _thread = sched::thread::current();
+        osv_reclaimer_thread = reinterpret_cast<unsigned char *>(_thread);
         allow_emergency_alloc = true;
         do {
             _do_reclaim();