Test reaching objsize_max under simulated memory pressure

Tests #22

src/fellow_cache.c

@@ -2148,6 +2148,9 @@ fellow_busy_region_alloc(struct fellow_busy *fbo, size_t size, int8_t cram)
 	assert(fbo->nregion < FCO_MAX_REGIONS);
 	fdr = &fbo->region[fbo->nregion];
 
+	if (cram)
+		FC_INJ_SZLIM(size);
+
 	*fdr = FC_INJ ? buddy_off_extent_nil :
 	    fellow_region_alloc(fc->ffd, FEP_SPC, size, cram);
 
@@ -5662,6 +5665,29 @@ t_cache(unsigned chksum)
 	test_bocdone(fbo, TRUST_ME(hash), 1);
 	fellow_cache_obj_deref(fc, fco);
 
+	// === hit objsize_max under memory pressure
+	fbo = fellow_busy_obj_alloc(fc, &fco, &priv2, 1234).r.ptr;
+	CHECK_OBJ_NOTNULL(fbo, FELLOW_BUSY_MAGIC);
+	do {
+		char *ptr;
+
+		if (fbo->nregion < FCO_MAX_REGIONS - FCO_REGIONS_RESERVE)
+			FC_INJ_SZLIM_SET(4096);
+
+		sz = 1234;
+		fcr = fellow_busy_obj_getspace(fbo, &sz, (uint8_t **)&ptr);
+		if (fcr.status == fcr_ok) {
+			fellow_busy_obj_extend(fbo, sz);
+			continue;
+		}
+		assert(fcr.status == fcr_allocerr);
+		AZ(strcmp(fcr.r.err, "objsize_max reached"));
+	} while (fcr.status == fcr_ok);
+
+	fellow_busy_obj_trimstore(fbo);
+	test_bocdone(fbo, TRUST_ME(hash), 1);
+	fellow_cache_obj_deref(fc, fco);
+
 	test_fellow_cache_unbusy_inject(fc);
 
 	// === alloc, then evict