Reduce stack used by ztest

While ztest does run in user space we run it with the same stack
restrictions it would have in kernel space.  This ensures that any
stack related issues which would be hit in the kernel can be caught
and debugged in user space instead.

This patch is a first pass to limit the stack usage of every ztest
function to 1024 bytes.  Subsequent updates can further reduce this

.topdeps

@@ -1 +1 @@
-master
+fix-pthreads

.topmsg

@@ -1,11 +1,12 @@
 From: Brian Behlendorf <behlendorf1@llnl.gov>
-Subject: [PATCH] fix pthreads
+Subject: [PATCH] fix stack ztest
 
-This is a portability change which removes the dependence of the Solaris
+While ztest does run in user space we run it with the same stack
-thread library.  All locations where Solaris thread API was used before
+restrictions it would have in kernel space.  This ensures that any
-have been replaced with equivilant Solaris kernel style thread calls.
+stack related issues which would be hit in the kernel can be caught
-In user space the kernel style threading API is implemented in term of
+and debugged in user space instead.
-the portable pthreads library.  This includes all threads, mutexs,
+
-condition variables, reader/writer locks, and taskqs.
+This patch is a first pass to limit the stack usage of every ztest
+function to 1024 bytes.  Subsequent updates can further reduce this
 
 Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>

cmd/ztest/ztest.c

@@ -382,9 +382,10 @@ fatal(int do_perror, char *message, ...)
 {
 	va_list args;
 	int save_errno = errno;
-	char buf[FATAL_MSG_SZ];
+	char *buf;
 
 	(void) fflush(stdout);
+	buf = umem_alloc(FATAL_MSG_SZ, UMEM_NOFAIL);
 
 	va_start(args, message);
 	(void) sprintf(buf, "ztest: ");
@@ -649,10 +650,12 @@ ztest_get_ashift(void)
 static nvlist_t *
 make_vdev_file(char *path, char *aux, size_t size, uint64_t ashift)
 {
-	char pathbuf[MAXPATHLEN];
+	char *pathbuf;
 	uint64_t vdev;
 	nvlist_t *file;
 
+	pathbuf = umem_alloc(MAXPATHLEN, UMEM_NOFAIL);
+
 	if (ashift == 0)
 		ashift = ztest_get_ashift();
 
@@ -683,6 +686,7 @@ make_vdev_file(char *path, char *aux, size_t size, uint64_t ashift)
 	VERIFY(nvlist_add_string(file, ZPOOL_CONFIG_TYPE, VDEV_TYPE_FILE) == 0);
 	VERIFY(nvlist_add_string(file, ZPOOL_CONFIG_PATH, path) == 0);
 	VERIFY(nvlist_add_uint64(file, ZPOOL_CONFIG_ASHIFT, ashift) == 0);
+	umem_free(pathbuf, MAXPATHLEN);
 
 	return (file);
 }
@@ -825,7 +829,7 @@ ztest_dsl_prop_set_uint64(char *osname, zfs_prop_t prop, uint64_t value,
 {
 	const char *propname = zfs_prop_to_name(prop);
 	const char *valname;
-	char setpoint[MAXPATHLEN];
+	char *setpoint;
 	uint64_t curval;
 	int error;
 
@@ -839,6 +843,7 @@ ztest_dsl_prop_set_uint64(char *osname, zfs_prop_t prop, uint64_t value,
 	}
 	ASSERT3U(error, ==, 0);
 
+	setpoint = umem_alloc(MAXPATHLEN, UMEM_NOFAIL);
 	VERIFY3U(dsl_prop_get(osname, propname, sizeof (curval),
 	    1, &curval, setpoint), ==, 0);
 
@@ -847,6 +852,7 @@ ztest_dsl_prop_set_uint64(char *osname, zfs_prop_t prop, uint64_t value,
 		(void) printf("%s %s = %s at '%s'\n",
 		    osname, propname, valname, setpoint);
 	}
+	umem_free(setpoint, MAXPATHLEN);
 
 	return (error);
 }
@@ -2219,9 +2225,12 @@ ztest_vdev_aux_add_remove(ztest_ds_t *zd, uint64_t id)
 	vdev_t *rvd = spa->spa_root_vdev;
 	spa_aux_vdev_t *sav;
 	char *aux;
+	char *path;
 	uint64_t guid = 0;
 	int error;
 
+	path = umem_alloc(MAXPATHLEN, UMEM_NOFAIL);
+
 	if (ztest_random(2) == 0) {
 		sav = &spa->spa_spares;
 		aux = ZPOOL_CONFIG_SPARES;
@@ -2245,7 +2254,6 @@ ztest_vdev_aux_add_remove(ztest_ds_t *zd, uint64_t id)
 		 */
 		zs->zs_vdev_aux = 0;
 		for (;;) {
-			char path[MAXPATHLEN];
 			int c;
 			(void) sprintf(path, ztest_aux_template, zopt_dir,
 			    zopt_pool, aux, zs->zs_vdev_aux);
@@ -2287,6 +2295,8 @@ ztest_vdev_aux_add_remove(ztest_ds_t *zd, uint64_t id)
 	}
 
 	mutex_exit(&zs->zs_vdev_lock);
+
+	umem_free(path, MAXPATHLEN);
 }
 
 /*
@@ -2403,13 +2413,16 @@ ztest_vdev_attach_detach(ztest_ds_t *zd, uint64_t id)
 	uint64_t ashift = ztest_get_ashift();
 	uint64_t oldguid, pguid;
 	size_t oldsize, newsize;
-	char oldpath[MAXPATHLEN], newpath[MAXPATHLEN];
+	char *oldpath, *newpath;
 	int replacing;
 	int oldvd_has_siblings = B_FALSE;
 	int newvd_is_spare = B_FALSE;
 	int oldvd_is_log;
 	int error, expected_error;
 
+	oldpath = umem_alloc(MAXPATHLEN, UMEM_NOFAIL);
+	newpath = umem_alloc(MAXPATHLEN, UMEM_NOFAIL);
+
 	mutex_enter(&zs->zs_vdev_lock);
 	leaves = MAX(zs->zs_mirrors, 1) * zopt_raidz;
 
@@ -2471,8 +2484,7 @@ ztest_vdev_attach_detach(ztest_ds_t *zd, uint64_t id)
 		if (error != 0 && error != ENODEV && error != EBUSY &&
 		    error != ENOTSUP)
 			fatal(0, "detach (%s) returned %d", oldpath, error);
-		mutex_exit(&zs->zs_vdev_lock);
+		goto out;
-		return;
 	}
 
 	/*
@@ -2563,8 +2575,11 @@ ztest_vdev_attach_detach(ztest_ds_t *zd, uint64_t id)
 		    oldpath, (longlong_t)oldsize, newpath,
 		    (longlong_t)newsize, replacing, error, expected_error);
 	}
-
+out:
 	mutex_exit(&zs->zs_vdev_lock);
+
+	umem_free(oldpath, MAXPATHLEN);
+	umem_free(newpath, MAXPATHLEN);
 }
 
 /*
@@ -2908,13 +2923,16 @@ void
 ztest_dmu_objset_create_destroy(ztest_ds_t *zd, uint64_t id)
 {
 	ztest_shared_t *zs = ztest_shared;
-	ztest_ds_t zdtmp;
+	ztest_ds_t *zdtmp;
 	int iters;
 	int error;
 	objset_t *os, *os2;
-	char name[MAXNAMELEN];
+	char *name;
 	zilog_t *zilog;
 
+	zdtmp = umem_alloc(sizeof (ztest_ds_t), UMEM_NOFAIL);
+	name = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
+
 	(void) rw_enter(&zs->zs_name_lock, RW_READER);
 
 	(void) snprintf(name, MAXNAMELEN, "%s/temp_%llu",
@@ -2927,9 +2945,9 @@ ztest_dmu_objset_create_destroy(ztest_ds_t *zd, uint64_t id)
 	 */
 	if (ztest_random(2) == 0 &&
 	    dmu_objset_own(name, DMU_OST_OTHER, B_FALSE, FTAG, &os) == 0) {
-		ztest_zd_init(&zdtmp, os);
+		ztest_zd_init(zdtmp, os);
-		zil_replay(os, &zdtmp, ztest_replay_vector);
+		zil_replay(os, zdtmp, ztest_replay_vector);
-		ztest_zd_fini(&zdtmp);
+		ztest_zd_fini(zdtmp);
 		dmu_objset_disown(os, FTAG);
 	}
 
@@ -2953,8 +2971,7 @@ ztest_dmu_objset_create_destroy(ztest_ds_t *zd, uint64_t id)
 	if (error) {
 		if (error == ENOSPC) {
 			ztest_record_enospc(FTAG);
-			(void) rw_exit(&zs->zs_name_lock);
+			goto out;
-			return;
 		}
 		fatal(0, "dmu_objset_create(%s) = %d", name, error);
 	}
@@ -2962,7 +2979,7 @@ ztest_dmu_objset_create_destroy(ztest_ds_t *zd, uint64_t id)
 	VERIFY3U(0, ==,
 	    dmu_objset_own(name, DMU_OST_OTHER, B_FALSE, FTAG, &os));
 
-	ztest_zd_init(&zdtmp, os);
+	ztest_zd_init(zdtmp, os);
 
 	/*
 	 * Open the intent log for it.
@@ -2975,7 +2992,7 @@ ztest_dmu_objset_create_destroy(ztest_ds_t *zd, uint64_t id)
 	 */
 	iters = ztest_random(5);
 	for (int i = 0; i < iters; i++) {
-		ztest_dmu_object_alloc_free(&zdtmp, id);
+		ztest_dmu_object_alloc_free(zdtmp, id);
 		if (ztest_random(iters) == 0)
 			(void) ztest_snapshot_create(name, i);
 	}
@@ -3000,9 +3017,12 @@ ztest_dmu_objset_create_destroy(ztest_ds_t *zd, uint64_t id)
 
 	zil_close(zilog);
 	dmu_objset_disown(os, FTAG);
-	ztest_zd_fini(&zdtmp);
+	ztest_zd_fini(zdtmp);
-
+out:
 	(void) rw_exit(&zs->zs_name_lock);
+
+	umem_free(name, MAXNAMELEN);
+	umem_free(zdtmp, sizeof (ztest_ds_t));
 }
 
 /*
@@ -3025,13 +3045,19 @@ ztest_dmu_snapshot_create_destroy(ztest_ds_t *zd, uint64_t id)
 void
 ztest_dsl_dataset_cleanup(char *osname, uint64_t id)
 {
-	char snap1name[MAXNAMELEN];
+	char *snap1name;
-	char clone1name[MAXNAMELEN];
+	char *clone1name;
-	char snap2name[MAXNAMELEN];
+	char *snap2name;
-	char clone2name[MAXNAMELEN];
+	char *clone2name;
-	char snap3name[MAXNAMELEN];
+	char *snap3name;
 	int error;
 
+	snap1name  = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
+	clone1name = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
+	snap2name  = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
+	clone2name = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
+	snap3name  = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
+
 	(void) snprintf(snap1name, MAXNAMELEN, "%s@s1_%llu", osname, id);
 	(void) snprintf(clone1name, MAXNAMELEN, "%s/c1_%llu", osname, id);
 	(void) snprintf(snap2name, MAXNAMELEN, "%s@s2_%llu", clone1name, id);
@@ -3053,6 +3079,12 @@ ztest_dsl_dataset_cleanup(char *osname, uint64_t id)
 	error = dmu_objset_destroy(snap1name, B_FALSE);
 	if (error && error != ENOENT)
 		fatal(0, "dmu_objset_destroy(%s) = %d", snap1name, error);
+
+	umem_free(snap1name, MAXNAMELEN);
+	umem_free(clone1name, MAXNAMELEN);
+	umem_free(snap2name, MAXNAMELEN);
+	umem_free(clone2name, MAXNAMELEN);
+	umem_free(snap3name, MAXNAMELEN);
 }
 
 /*
@@ -3064,14 +3096,20 @@ ztest_dsl_dataset_promote_busy(ztest_ds_t *zd, uint64_t id)
 	ztest_shared_t *zs = ztest_shared;
 	objset_t *clone;
 	dsl_dataset_t *ds;
-	char snap1name[MAXNAMELEN];
+	char *snap1name;
-	char clone1name[MAXNAMELEN];
+	char *clone1name;
-	char snap2name[MAXNAMELEN];
+	char *snap2name;
-	char clone2name[MAXNAMELEN];
+	char *clone2name;
-	char snap3name[MAXNAMELEN];
+	char *snap3name;
 	char *osname = zd->zd_name;
 	int error;
 
+	snap1name  = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
+	clone1name = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
+	snap2name  = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
+	clone2name = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
+	snap3name  = umem_alloc(MAXNAMELEN, UMEM_NOFAIL);
+
 	(void) rw_enter(&zs->zs_name_lock, RW_READER);
 
 	ztest_dsl_dataset_cleanup(osname, id);
@@ -3153,30 +3191,45 @@ out:
 	ztest_dsl_dataset_cleanup(osname, id);
 
 	(void) rw_exit(&zs->zs_name_lock);
+
+	umem_free(snap1name, MAXNAMELEN);
+	umem_free(clone1name, MAXNAMELEN);
+	umem_free(snap2name, MAXNAMELEN);
+	umem_free(clone2name, MAXNAMELEN);
+	umem_free(snap3name, MAXNAMELEN);
 }
 
+#define OD_ARRAY_SIZE	4
+
 /*
  * Verify that dmu_object_{alloc,free} work as expected.
  */
 void
 ztest_dmu_object_alloc_free(ztest_ds_t *zd, uint64_t id)
 {
-	ztest_od_t od[4];
+	ztest_od_t *od;
-	int batchsize = sizeof (od) / sizeof (od[0]);
+	int batchsize;
+	int size;
+
+	size = sizeof(ztest_od_t) * OD_ARRAY_SIZE;
+	od = umem_alloc(size, UMEM_NOFAIL);
+	batchsize = OD_ARRAY_SIZE;
 
 	for (int b = 0; b < batchsize; b++)
-		ztest_od_init(&od[b], id, FTAG, b, DMU_OT_UINT64_OTHER, 0, 0);
+		ztest_od_init(od + b, id, FTAG, b, DMU_OT_UINT64_OTHER, 0, 0);
 
 	/*
 	 * Destroy the previous batch of objects, create a new batch,
 	 * and do some I/O on the new objects.
 	 */
-	if (ztest_object_init(zd, od, sizeof (od), B_TRUE) != 0)
+	if (ztest_object_init(zd, od, size, B_TRUE) != 0)
 		return;
 
 	while (ztest_random(4 * batchsize) != 0)
 		ztest_io(zd, od[ztest_random(batchsize)].od_object,
 		    ztest_random(ZTEST_RANGE_LOCKS) << SPA_MAXBLOCKSHIFT);
+
+	umem_free(od, size);
 }
 
 /*
@@ -4399,8 +4452,8 @@ ztest_fault_inject(ztest_ds_t *zd, uint64_t id)
 	uint64_t leaves;
 	uint64_t bad = 0x1990c0ffeedecade;
 	uint64_t top, leaf;
-	char path0[MAXPATHLEN];
+	char *path0;
-	char pathrand[MAXPATHLEN];
+	char *pathrand;
 	size_t fsize;
 	int bshift = SPA_MAXBLOCKSHIFT + 2;	/* don't scrog all labels */
 	int iters = 1000;
@@ -4410,6 +4463,9 @@ ztest_fault_inject(ztest_ds_t *zd, uint64_t id)
 	uint64_t guid0 = 0;
 	boolean_t islog = B_FALSE;
 
+	path0 = umem_alloc(MAXPATHLEN, UMEM_NOFAIL);
+	pathrand = umem_alloc(MAXPATHLEN, UMEM_NOFAIL);
+
 	mutex_enter(&zs->zs_vdev_lock);
 	maxfaults = MAXFAULTS();
 	leaves = MAX(zs->zs_mirrors, 1) * zopt_raidz;
@@ -4476,7 +4532,7 @@ ztest_fault_inject(ztest_ds_t *zd, uint64_t id)
 
 		if (sav->sav_count == 0) {
 			spa_config_exit(spa, SCL_STATE, FTAG);
-			return;
+			goto out;
 		}
 		vd0 = sav->sav_vdevs[ztest_random(sav->sav_count)];
 		guid0 = vd0->vdev_guid;
@@ -4521,7 +4577,7 @@ ztest_fault_inject(ztest_ds_t *zd, uint64_t id)
 	}
 
 	if (maxfaults == 0)
-		return;
+		goto out;
 
 	/*
 	 * We have at least single-fault tolerance, so inject data corruption.
@@ -4529,7 +4585,7 @@ ztest_fault_inject(ztest_ds_t *zd, uint64_t id)
 	fd = open(pathrand, O_RDWR);
 
 	if (fd == -1)	/* we hit a gap in the device namespace */
-		return;
+		goto out;
 
 	fsize = lseek(fd, 0, SEEK_END);
 
@@ -4545,7 +4601,7 @@ ztest_fault_inject(ztest_ds_t *zd, uint64_t id)
 		if (mirror_save != zs->zs_mirrors) {
 			mutex_exit(&zs->zs_vdev_lock);
 			(void) close(fd);
-			return;
+			goto out;
 		}
 
 		if (pwrite(fd, &bad, sizeof (bad), offset) != sizeof (bad))
@@ -4560,6 +4616,9 @@ ztest_fault_inject(ztest_ds_t *zd, uint64_t id)
 	}
 
 	(void) close(fd);
+out:
+	umem_free(path0, MAXPATHLEN);
+	umem_free(pathrand, MAXPATHLEN);
 }
 
 /*