4 * This file and its contents are supplied under the terms of the
5 * Common Development and Distribution License ("CDDL"), version 1.0.
6 * You may only use this file in accordance with the terms of version
9 * A full copy of the text of the CDDL should have accompanied this
10 * source. A copy of the CDDL is also available via the Internet at
11 * http://www.illumos.org/license/CDDL.
17 * Copyright (c) 2016, 2018 by Delphix. All rights reserved.
21 * ZFS Channel Programs (ZCP)
23 * The ZCP interface allows various ZFS commands and operations ZFS
24 * administrative operations (e.g. creating and destroying snapshots, typically
25 * performed via an ioctl to /dev/zfs by the zfs(8) command and
26 * libzfs/libzfs_core) to be run * programmatically as a Lua script. A ZCP
27 * script is run as a dsl_sync_task and fully executed during one transaction
28 * group sync. This ensures that no other changes can be written concurrently
29 * with a running Lua script. Combining multiple calls to the exposed ZFS
30 * functions into one script gives a number of benefits:
32 * 1. Atomicity. For some compound or iterative operations, it's useful to be
33 * able to guarantee that the state of a pool has not changed between calls to
36 * 2. Performance. If a large number of changes need to be made (e.g. deleting
37 * many filesystems), there can be a significant performance penalty as a
38 * result of the need to wait for a transaction group sync to pass for every
39 * single operation. When expressed as a single ZCP script, all these changes
40 * can be performed at once in one txg sync.
42 * A modified version of the Lua 5.2 interpreter is used to run channel program
43 * scripts. The Lua 5.2 manual can be found at:
45 * http://www.lua.org/manual/5.2/
47 * If being run by a user (via an ioctl syscall), executing a ZCP script
48 * requires root privileges in the global zone.
50 * Scripts are passed to zcp_eval() as a string, then run in a synctask by
51 * zcp_eval_sync(). Arguments can be passed into the Lua script as an nvlist,
52 * which will be converted to a Lua table. Similarly, values returned from
53 * a ZCP script will be converted to an nvlist. See zcp_lua_to_nvlist_impl()
54 * for details on exact allowed types and conversion.
56 * ZFS functionality is exposed to a ZCP script as a library of function calls.
57 * These calls are sorted into submodules, such as zfs.list and zfs.sync, for
58 * iterators and synctasks, respectively. Each of these submodules resides in
59 * its own source file, with a zcp_*_info structure describing each library
60 * call in the submodule.
62 * Error handling in ZCP scripts is handled by a number of different methods
65 * 1. Memory and time limits are in place to prevent a channel program from
66 * consuming excessive system or running forever. If one of these limits is
67 * hit, the channel program will be stopped immediately and return from
68 * zcp_eval() with an error code. No attempt will be made to roll back or undo
69 * any changes made by the channel program before the error occured.
70 * Consumers invoking zcp_eval() from elsewhere in the kernel may pass a time
71 * limit of 0, disabling the time limit.
73 * 2. Internal Lua errors can occur as a result of a syntax error, calling a
74 * library function with incorrect arguments, invoking the error() function,
75 * failing an assert(), or other runtime errors. In these cases the channel
76 * program will stop executing and return from zcp_eval() with an error code.
77 * In place of a return value, an error message will also be returned in the
78 * 'result' nvlist containing information about the error. No attempt will be
79 * made to roll back or undo any changes made by the channel program before the
82 * 3. If an error occurs inside a ZFS library call which returns an error code,
83 * the error is returned to the Lua script to be handled as desired.
85 * In the first two cases, Lua's error-throwing mechanism is used, which
86 * longjumps out of the script execution with luaL_error() and returns with the
89 * See zfs-program(8) for more information on high level usage.
92 #include <sys/lua/lua.h>
93 #include <sys/lua/lualib.h>
94 #include <sys/lua/lauxlib.h>
96 #include <sys/dsl_prop.h>
97 #include <sys/dsl_synctask.h>
98 #include <sys/dsl_dataset.h>
100 #include <sys/zcp_iter.h>
101 #include <sys/zcp_prop.h>
102 #include <sys/zcp_global.h>
105 #define KM_NORMALPRI 0
108 #define ZCP_NVLIST_MAX_DEPTH 20
110 uint64_t zfs_lua_check_instrlimit_interval = 100;
111 unsigned long zfs_lua_max_instrlimit = ZCP_MAX_INSTRLIMIT;
112 unsigned long zfs_lua_max_memlimit = ZCP_MAX_MEMLIMIT;
115 * Forward declarations for mutually recursive functions
117 static int zcp_nvpair_value_to_lua(lua_State *, nvpair_t *, char *, int);
118 static int zcp_lua_to_nvlist_impl(lua_State *, int, nvlist_t *, const char *,
121 typedef struct zcp_alloc_arg {
122 boolean_t aa_must_succeed;
123 int64_t aa_alloc_remaining;
124 int64_t aa_alloc_limit;
127 typedef struct zcp_eval_arg {
129 zcp_alloc_arg_t *ea_allocargs;
133 uint64_t ea_instrlimit;
137 * The outer-most error callback handler for use with lua_pcall(). On
138 * error Lua will call this callback with a single argument that
139 * represents the error value. In most cases this will be a string
140 * containing an error message, but channel programs can use Lua's
141 * error() function to return arbitrary objects as errors. This callback
142 * returns (on the Lua stack) the original error object along with a traceback.
144 * Fatal Lua errors can occur while resources are held, so we also call any
145 * registered cleanup function here.
148 zcp_error_handler(lua_State *state)
154 VERIFY3U(1, ==, lua_gettop(state));
155 msg = lua_tostring(state, 1);
156 luaL_traceback(state, state, msg, 1);
161 zcp_argerror(lua_State *state, int narg, const char *msg, ...)
165 va_start(alist, msg);
166 const char *buf = lua_pushvfstring(state, msg, alist);
169 return (luaL_argerror(state, narg, buf));
173 * Install a new cleanup function, which will be invoked with the given
174 * opaque argument if a fatal error causes the Lua interpreter to longjump out
175 * of a function call.
177 * If an error occurs, the cleanup function will be invoked exactly once and
180 * Returns the registered cleanup handler so the caller can deregister it
181 * if no error occurs.
183 zcp_cleanup_handler_t *
184 zcp_register_cleanup(lua_State *state, zcp_cleanup_t cleanfunc, void *cleanarg)
186 zcp_run_info_t *ri = zcp_run_info(state);
188 zcp_cleanup_handler_t *zch = kmem_alloc(sizeof (*zch), KM_SLEEP);
189 zch->zch_cleanup_func = cleanfunc;
190 zch->zch_cleanup_arg = cleanarg;
191 list_insert_head(&ri->zri_cleanup_handlers, zch);
197 zcp_deregister_cleanup(lua_State *state, zcp_cleanup_handler_t *zch)
199 zcp_run_info_t *ri = zcp_run_info(state);
200 list_remove(&ri->zri_cleanup_handlers, zch);
201 kmem_free(zch, sizeof (*zch));
205 * Execute the currently registered cleanup handlers then free them and
206 * destroy the handler list.
209 zcp_cleanup(lua_State *state)
211 zcp_run_info_t *ri = zcp_run_info(state);
213 for (zcp_cleanup_handler_t *zch =
214 list_remove_head(&ri->zri_cleanup_handlers); zch != NULL;
215 zch = list_remove_head(&ri->zri_cleanup_handlers)) {
216 zch->zch_cleanup_func(zch->zch_cleanup_arg);
217 kmem_free(zch, sizeof (*zch));
222 * Convert the lua table at the given index on the Lua stack to an nvlist
225 * If the table can not be converted for any reason, NULL is returned and
226 * an error message is pushed onto the Lua stack.
229 zcp_table_to_nvlist(lua_State *state, int index, int depth)
233 * Converting a Lua table to an nvlist with key uniqueness checking is
234 * O(n^2) in the number of keys in the nvlist, which can take a long
235 * time when we return a large table from a channel program.
236 * Furthermore, Lua's table interface *almost* guarantees unique keys
237 * on its own (details below). Therefore, we don't use fnvlist_alloc()
238 * here to avoid the built-in uniqueness checking.
240 * The *almost* is because it's possible to have key collisions between
241 * e.g. the string "1" and the number 1, or the string "true" and the
242 * boolean true, so we explicitly check that when we're looking at a
243 * key which is an integer / boolean or a string that can be parsed as
244 * one of those types. In the worst case this could still devolve into
245 * O(n^2), so we only start doing these checks on boolean/integer keys
246 * once we've seen a string key which fits this weird usage pattern.
248 * Ultimately, we still want callers to know that the keys in this
249 * nvlist are unique, so before we return this we set the nvlist's
250 * flags to reflect that.
252 VERIFY0(nvlist_alloc(&nvl, 0, KM_SLEEP));
255 * Push an empty stack slot where lua_next() will store each
259 boolean_t saw_str_could_collide = B_FALSE;
260 while (lua_next(state, index) != 0) {
262 * The next key-value pair from the table at index is
263 * now on the stack, with the key at stack slot -2 and
264 * the value at slot -1.
268 const char *key = NULL;
269 boolean_t key_could_collide = B_FALSE;
271 switch (lua_type(state, -2)) {
273 key = lua_tostring(state, -2);
275 /* check if this could collide with a number or bool */
278 if ((sscanf(key, "%lld%n", &tmp, &parselen) > 0 &&
279 parselen == strlen(key)) ||
280 strcmp(key, "true") == 0 ||
281 strcmp(key, "false") == 0) {
282 key_could_collide = B_TRUE;
283 saw_str_could_collide = B_TRUE;
287 key = (lua_toboolean(state, -2) == B_TRUE ?
289 if (saw_str_could_collide) {
290 key_could_collide = B_TRUE;
294 VERIFY3U(sizeof (buf), >,
295 snprintf(buf, sizeof (buf), "%lld",
296 (longlong_t)lua_tonumber(state, -2)));
298 if (saw_str_could_collide) {
299 key_could_collide = B_TRUE;
304 (void) lua_pushfstring(state, "Invalid key "
305 "type '%s' in table",
306 lua_typename(state, lua_type(state, -2)));
310 * Check for type-mismatched key collisions, and throw an error.
312 if (key_could_collide && nvlist_exists(nvl, key)) {
314 (void) lua_pushfstring(state, "Collision of "
315 "key '%s' in table", key);
319 * Recursively convert the table value and insert into
320 * the new nvlist with the parsed key. To prevent
321 * stack overflow on circular or heavily nested tables,
322 * we track the current nvlist depth.
324 if (depth >= ZCP_NVLIST_MAX_DEPTH) {
326 (void) lua_pushfstring(state, "Maximum table "
327 "depth (%d) exceeded for table",
328 ZCP_NVLIST_MAX_DEPTH);
331 err = zcp_lua_to_nvlist_impl(state, -1, nvl, key,
336 * Error message has been pushed to the lua
337 * stack by the recursive call.
342 * Pop the value pushed by lua_next().
348 * Mark the nvlist as having unique keys. This is a little ugly, but we
349 * ensured above that there are no duplicate keys in the nvlist.
351 nvl->nvl_nvflag |= NV_UNIQUE_NAME;
357 * Convert a value from the given index into the lua stack to an nvpair, adding
358 * it to an nvlist with the given key.
360 * Values are converted as follows:
365 * nil -> boolean (no value)
367 * Lua tables are converted to nvlists and then inserted. The table's keys
368 * are converted to strings then used as keys in the nvlist to store each table
369 * element. Keys are converted as follows:
371 * string -> no change
373 * boolean -> "true" | "false"
376 * In the case of a key collision, an error is thrown.
378 * If an error is encountered, a nonzero error code is returned, and an error
379 * string will be pushed onto the Lua stack.
382 zcp_lua_to_nvlist_impl(lua_State *state, int index, nvlist_t *nvl,
383 const char *key, int depth)
386 * Verify that we have enough remaining space in the lua stack to parse
387 * a key-value pair and push an error.
389 if (!lua_checkstack(state, 3)) {
390 (void) lua_pushstring(state, "Lua stack overflow");
394 index = lua_absindex(state, index);
396 switch (lua_type(state, index)) {
398 fnvlist_add_boolean(nvl, key);
401 fnvlist_add_boolean_value(nvl, key,
402 lua_toboolean(state, index));
405 fnvlist_add_int64(nvl, key, lua_tonumber(state, index));
408 fnvlist_add_string(nvl, key, lua_tostring(state, index));
411 nvlist_t *value_nvl = zcp_table_to_nvlist(state, index, depth);
412 if (value_nvl == NULL)
415 fnvlist_add_nvlist(nvl, key, value_nvl);
416 fnvlist_free(value_nvl);
420 (void) lua_pushfstring(state,
421 "Invalid value type '%s' for key '%s'",
422 lua_typename(state, lua_type(state, index)), key);
430 * Convert a lua value to an nvpair, adding it to an nvlist with the given key.
433 zcp_lua_to_nvlist(lua_State *state, int index, nvlist_t *nvl, const char *key)
436 * On error, zcp_lua_to_nvlist_impl pushes an error string onto the Lua
437 * stack before returning with a nonzero error code. If an error is
438 * returned, throw a fatal lua error with the given string.
440 if (zcp_lua_to_nvlist_impl(state, index, nvl, key, 0) != 0)
441 (void) lua_error(state);
445 zcp_lua_to_nvlist_helper(lua_State *state)
447 nvlist_t *nv = (nvlist_t *)lua_touserdata(state, 2);
448 const char *key = (const char *)lua_touserdata(state, 1);
449 zcp_lua_to_nvlist(state, 3, nv, key);
454 zcp_convert_return_values(lua_State *state, nvlist_t *nvl,
455 const char *key, zcp_eval_arg_t *evalargs)
458 VERIFY3U(1, ==, lua_gettop(state));
459 lua_pushcfunction(state, zcp_lua_to_nvlist_helper);
460 lua_pushlightuserdata(state, (char *)key);
461 lua_pushlightuserdata(state, nvl);
462 lua_pushvalue(state, 1);
463 lua_remove(state, 1);
464 err = lua_pcall(state, 3, 0, 0); /* zcp_lua_to_nvlist_helper */
466 zcp_lua_to_nvlist(state, 1, nvl, ZCP_RET_ERROR);
467 evalargs->ea_result = SET_ERROR(ECHRNG);
472 * Push a Lua table representing nvl onto the stack. If it can't be
473 * converted, return EINVAL, fill in errbuf, and push nothing. errbuf may
474 * be specified as NULL, in which case no error string will be output.
476 * Most nvlists are converted as simple key->value Lua tables, but we make
477 * an exception for the case where all nvlist entries are BOOLEANs (a string
478 * key without a value). In Lua, a table key pointing to a value of Nil
479 * (no value) is equivalent to the key not existing, so a BOOLEAN nvlist
480 * entry can't be directly converted to a Lua table entry. Nvlists of entirely
481 * BOOLEAN entries are frequently used to pass around lists of datasets, so for
482 * convenience we check for this case, and convert it to a simple Lua array of
486 zcp_nvlist_to_lua(lua_State *state, nvlist_t *nvl,
487 char *errbuf, int errbuf_len)
491 boolean_t has_values = B_FALSE;
493 * If the list doesn't have any values, just convert it to a string
496 for (pair = nvlist_next_nvpair(nvl, NULL);
497 pair != NULL; pair = nvlist_next_nvpair(nvl, pair)) {
498 if (nvpair_type(pair) != DATA_TYPE_BOOLEAN) {
505 for (pair = nvlist_next_nvpair(nvl, NULL);
506 pair != NULL; pair = nvlist_next_nvpair(nvl, pair)) {
507 (void) lua_pushinteger(state, i);
508 (void) lua_pushstring(state, nvpair_name(pair));
509 (void) lua_settable(state, -3);
513 for (pair = nvlist_next_nvpair(nvl, NULL);
514 pair != NULL; pair = nvlist_next_nvpair(nvl, pair)) {
515 int err = zcp_nvpair_value_to_lua(state, pair,
521 (void) lua_setfield(state, -2, nvpair_name(pair));
528 * Push a Lua object representing the value of "pair" onto the stack.
530 * Only understands boolean_value, string, int64, nvlist,
531 * string_array, and int64_array type values. For other
532 * types, returns EINVAL, fills in errbuf, and pushes nothing.
535 zcp_nvpair_value_to_lua(lua_State *state, nvpair_t *pair,
536 char *errbuf, int errbuf_len)
545 switch (nvpair_type(pair)) {
546 case DATA_TYPE_BOOLEAN_VALUE:
547 (void) lua_pushboolean(state,
548 fnvpair_value_boolean_value(pair));
550 case DATA_TYPE_STRING:
551 (void) lua_pushstring(state, fnvpair_value_string(pair));
553 case DATA_TYPE_INT64:
554 (void) lua_pushinteger(state, fnvpair_value_int64(pair));
556 case DATA_TYPE_NVLIST:
557 err = zcp_nvlist_to_lua(state,
558 fnvpair_value_nvlist(pair), errbuf, errbuf_len);
560 case DATA_TYPE_STRING_ARRAY: {
563 (void) nvpair_value_string_array(pair, &strarr, &nelem);
565 for (int i = 0; i < nelem; i++) {
566 (void) lua_pushinteger(state, i + 1);
567 (void) lua_pushstring(state, strarr[i]);
568 (void) lua_settable(state, -3);
572 case DATA_TYPE_UINT64_ARRAY: {
575 (void) nvpair_value_uint64_array(pair, &intarr, &nelem);
577 for (int i = 0; i < nelem; i++) {
578 (void) lua_pushinteger(state, i + 1);
579 (void) lua_pushinteger(state, intarr[i]);
580 (void) lua_settable(state, -3);
584 case DATA_TYPE_INT64_ARRAY: {
587 (void) nvpair_value_int64_array(pair, &intarr, &nelem);
589 for (int i = 0; i < nelem; i++) {
590 (void) lua_pushinteger(state, i + 1);
591 (void) lua_pushinteger(state, intarr[i]);
592 (void) lua_settable(state, -3);
597 if (errbuf != NULL) {
598 (void) snprintf(errbuf, errbuf_len,
599 "Unhandled nvpair type %d for key '%s'",
600 nvpair_type(pair), nvpair_name(pair));
609 zcp_dataset_hold_error(lua_State *state, dsl_pool_t *dp, const char *dsname,
612 if (error == ENOENT) {
613 (void) zcp_argerror(state, 1, "no such dataset '%s'", dsname);
614 return (0); /* not reached; zcp_argerror will longjmp */
615 } else if (error == EXDEV) {
616 (void) zcp_argerror(state, 1,
617 "dataset '%s' is not in the target pool '%s'",
618 dsname, spa_name(dp->dp_spa));
619 return (0); /* not reached; zcp_argerror will longjmp */
620 } else if (error == EIO) {
621 (void) luaL_error(state,
622 "I/O error while accessing dataset '%s'", dsname);
623 return (0); /* not reached; luaL_error will longjmp */
624 } else if (error != 0) {
625 (void) luaL_error(state,
626 "unexpected error %d while accessing dataset '%s'",
628 return (0); /* not reached; luaL_error will longjmp */
634 * Note: will longjmp (via lua_error()) on error.
635 * Assumes that the dsname is argument #1 (for error reporting purposes).
638 zcp_dataset_hold(lua_State *state, dsl_pool_t *dp, const char *dsname,
642 int error = dsl_dataset_hold(dp, dsname, tag, &ds);
643 (void) zcp_dataset_hold_error(state, dp, dsname, error);
647 static int zcp_debug(lua_State *);
648 static zcp_lib_info_t zcp_debug_info = {
652 { .za_name = "debug string", .za_lua_type = LUA_TSTRING},
661 zcp_debug(lua_State *state)
663 const char *dbgstring;
664 zcp_run_info_t *ri = zcp_run_info(state);
665 zcp_lib_info_t *libinfo = &zcp_debug_info;
667 zcp_parse_args(state, libinfo->name, libinfo->pargs, libinfo->kwargs);
669 dbgstring = lua_tostring(state, 1);
671 zfs_dbgmsg("txg %lld ZCP: %s", ri->zri_tx->tx_txg, dbgstring);
676 static int zcp_exists(lua_State *);
677 static zcp_lib_info_t zcp_exists_info = {
681 { .za_name = "dataset", .za_lua_type = LUA_TSTRING},
690 zcp_exists(lua_State *state)
692 zcp_run_info_t *ri = zcp_run_info(state);
693 dsl_pool_t *dp = ri->zri_pool;
694 zcp_lib_info_t *libinfo = &zcp_exists_info;
696 zcp_parse_args(state, libinfo->name, libinfo->pargs, libinfo->kwargs);
698 const char *dsname = lua_tostring(state, 1);
701 int error = dsl_dataset_hold(dp, dsname, FTAG, &ds);
703 dsl_dataset_rele(ds, FTAG);
704 lua_pushboolean(state, B_TRUE);
705 } else if (error == ENOENT) {
706 lua_pushboolean(state, B_FALSE);
707 } else if (error == EXDEV) {
708 return (luaL_error(state, "dataset '%s' is not in the "
709 "target pool", dsname));
710 } else if (error == EIO) {
711 return (luaL_error(state, "I/O error opening dataset '%s'",
713 } else if (error != 0) {
714 return (luaL_error(state, "unexpected error %d", error));
721 * Allocate/realloc/free a buffer for the lua interpreter.
723 * When nsize is 0, behaves as free() and returns NULL.
725 * If ptr is NULL, behaves as malloc() and returns an allocated buffer of size
728 * Otherwise, behaves as realloc(), changing the allocation from osize to nsize.
729 * Shrinking the buffer size never fails.
731 * The original allocated buffer size is stored as a uint64 at the beginning of
732 * the buffer to avoid actually reallocating when shrinking a buffer, since lua
733 * requires that this operation never fail.
736 zcp_lua_alloc(void *ud, void *ptr, size_t osize, size_t nsize)
738 zcp_alloc_arg_t *allocargs = ud;
739 int flags = (allocargs->aa_must_succeed) ?
740 KM_SLEEP : (KM_NOSLEEP | KM_NORMALPRI);
744 int64_t *allocbuf = (int64_t *)ptr - 1;
745 int64_t allocsize = *allocbuf;
746 ASSERT3S(allocsize, >, 0);
747 ASSERT3S(allocargs->aa_alloc_remaining + allocsize, <=,
748 allocargs->aa_alloc_limit);
749 allocargs->aa_alloc_remaining += allocsize;
750 vmem_free(allocbuf, allocsize);
753 } else if (ptr == NULL) {
755 int64_t allocsize = nsize + sizeof (int64_t);
757 if (!allocargs->aa_must_succeed &&
759 allocsize > allocargs->aa_alloc_remaining)) {
763 allocbuf = vmem_alloc(allocsize, flags);
764 if (allocbuf == NULL) {
767 allocargs->aa_alloc_remaining -= allocsize;
769 *allocbuf = allocsize;
770 return (allocbuf + 1);
771 } else if (nsize <= osize) {
773 * If shrinking the buffer, lua requires that the reallocation
778 ASSERT3U(nsize, >, osize);
780 uint64_t *luabuf = zcp_lua_alloc(ud, NULL, 0, nsize);
781 if (luabuf == NULL) {
784 (void) memcpy(luabuf, ptr, osize);
785 VERIFY3P(zcp_lua_alloc(ud, ptr, osize, 0), ==, NULL);
792 zcp_lua_counthook(lua_State *state, lua_Debug *ar)
795 * If we're called, check how many instructions the channel program has
796 * executed so far, and compare against the limit.
798 lua_getfield(state, LUA_REGISTRYINDEX, ZCP_RUN_INFO_KEY);
799 zcp_run_info_t *ri = lua_touserdata(state, -1);
801 ri->zri_curinstrs += zfs_lua_check_instrlimit_interval;
802 if (ri->zri_maxinstrs != 0 && ri->zri_curinstrs > ri->zri_maxinstrs) {
803 ri->zri_timed_out = B_TRUE;
804 (void) lua_pushstring(state,
805 "Channel program timed out.");
806 (void) lua_error(state);
811 zcp_panic_cb(lua_State *state)
813 panic("unprotected error in call to Lua API (%s)\n",
814 lua_tostring(state, -1));
819 zcp_eval_impl(dmu_tx_t *tx, boolean_t sync, zcp_eval_arg_t *evalargs)
823 lua_State *state = evalargs->ea_state;
825 VERIFY3U(3, ==, lua_gettop(state));
828 * Store the zcp_run_info_t struct for this run in the Lua registry.
829 * Registry entries are not directly accessible by the Lua scripts but
830 * can be accessed by our callbacks.
832 ri.zri_space_used = 0;
833 ri.zri_pool = dmu_tx_pool(tx);
834 ri.zri_cred = evalargs->ea_cred;
836 ri.zri_timed_out = B_FALSE;
838 list_create(&ri.zri_cleanup_handlers, sizeof (zcp_cleanup_handler_t),
839 offsetof(zcp_cleanup_handler_t, zch_node));
840 ri.zri_curinstrs = 0;
841 ri.zri_maxinstrs = evalargs->ea_instrlimit;
843 lua_pushlightuserdata(state, &ri);
844 lua_setfield(state, LUA_REGISTRYINDEX, ZCP_RUN_INFO_KEY);
845 VERIFY3U(3, ==, lua_gettop(state));
848 * Tell the Lua interpreter to call our handler every count
849 * instructions. Channel programs that execute too many instructions
850 * should die with ETIME.
852 (void) lua_sethook(state, zcp_lua_counthook, LUA_MASKCOUNT,
853 zfs_lua_check_instrlimit_interval);
856 * Tell the Lua memory allocator to stop using KM_SLEEP before handing
857 * off control to the channel program. Channel programs that use too
858 * much memory should die with ENOSPC.
860 evalargs->ea_allocargs->aa_must_succeed = B_FALSE;
863 * Call the Lua function that open-context passed us. This pops the
864 * function and its input from the stack and pushes any return
867 err = lua_pcall(state, 1, LUA_MULTRET, 1);
870 * Let Lua use KM_SLEEP while we interpret the return values.
872 evalargs->ea_allocargs->aa_must_succeed = B_TRUE;
875 * Remove the error handler callback from the stack. At this point,
876 * there shouldn't be any cleanup handler registered in the handler
877 * list (zri_cleanup_handlers), regardless of whether it ran or not.
879 list_destroy(&ri.zri_cleanup_handlers);
880 lua_remove(state, 1);
885 * Lua supports returning multiple values in a single return
886 * statement. Return values will have been pushed onto the
891 * To simplify the process of retrieving a return value from a
892 * channel program, we disallow returning more than one value
893 * to ZFS from the Lua script, yielding a singleton return
894 * nvlist of the form { "return": Return value 1 }.
896 int return_count = lua_gettop(state);
898 if (return_count == 1) {
899 evalargs->ea_result = 0;
900 zcp_convert_return_values(state, evalargs->ea_outnvl,
901 ZCP_RET_RETURN, evalargs);
902 } else if (return_count > 1) {
903 evalargs->ea_result = SET_ERROR(ECHRNG);
904 lua_settop(state, 0);
905 (void) lua_pushfstring(state, "Multiple return "
906 "values not supported");
907 zcp_convert_return_values(state, evalargs->ea_outnvl,
908 ZCP_RET_ERROR, evalargs);
915 * The channel program encountered a fatal error within the
916 * script, such as failing an assertion, or calling a function
917 * with incompatible arguments. The error value and the
918 * traceback generated by zcp_error_handler() should be on the
921 VERIFY3U(1, ==, lua_gettop(state));
922 if (ri.zri_timed_out) {
923 evalargs->ea_result = SET_ERROR(ETIME);
925 evalargs->ea_result = SET_ERROR(ECHRNG);
928 zcp_convert_return_values(state, evalargs->ea_outnvl,
929 ZCP_RET_ERROR, evalargs);
931 if (evalargs->ea_result == ETIME &&
932 evalargs->ea_outnvl != NULL) {
933 (void) nvlist_add_uint64(evalargs->ea_outnvl,
934 ZCP_ARG_INSTRLIMIT, ri.zri_curinstrs);
940 * The channel program encountered a fatal error within the
941 * script, and we encountered another error while trying to
942 * compute the traceback in zcp_error_handler(). We can only
943 * return the error message.
945 VERIFY3U(1, ==, lua_gettop(state));
946 if (ri.zri_timed_out) {
947 evalargs->ea_result = SET_ERROR(ETIME);
949 evalargs->ea_result = SET_ERROR(ECHRNG);
952 zcp_convert_return_values(state, evalargs->ea_outnvl,
953 ZCP_RET_ERROR, evalargs);
958 * Lua ran out of memory while running the channel program.
959 * There's not much we can do.
961 evalargs->ea_result = SET_ERROR(ENOSPC);
969 zcp_pool_error(zcp_eval_arg_t *evalargs, const char *poolname)
971 evalargs->ea_result = SET_ERROR(ECHRNG);
972 lua_settop(evalargs->ea_state, 0);
973 (void) lua_pushfstring(evalargs->ea_state, "Could not open pool: %s",
975 zcp_convert_return_values(evalargs->ea_state, evalargs->ea_outnvl,
976 ZCP_RET_ERROR, evalargs);
981 zcp_eval_sync(void *arg, dmu_tx_t *tx)
983 zcp_eval_arg_t *evalargs = arg;
986 * Open context should have setup the stack to contain:
987 * 1: Error handler callback
988 * 2: Script to run (converted to a Lua function)
989 * 3: nvlist input to function (converted to Lua table or nil)
991 VERIFY3U(3, ==, lua_gettop(evalargs->ea_state));
993 zcp_eval_impl(tx, B_TRUE, evalargs);
997 zcp_eval_open(zcp_eval_arg_t *evalargs, const char *poolname)
1005 * See comment from the same assertion in zcp_eval_sync().
1007 VERIFY3U(3, ==, lua_gettop(evalargs->ea_state));
1009 error = dsl_pool_hold(poolname, FTAG, &dp);
1011 zcp_pool_error(evalargs, poolname);
1016 * As we are running in open-context, we have no transaction associated
1017 * with the channel program. At the same time, functions from the
1018 * zfs.check submodule need to be associated with a transaction as
1019 * they are basically dry-runs of their counterparts in the zfs.sync
1020 * submodule. These functions should be able to run in open-context.
1021 * Therefore we create a new transaction that we later abort once
1022 * the channel program has been evaluated.
1024 tx = dmu_tx_create_dd(dp->dp_mos_dir);
1026 zcp_eval_impl(tx, B_FALSE, evalargs);
1030 dsl_pool_rele(dp, FTAG);
1034 zcp_eval(const char *poolname, const char *program, boolean_t sync,
1035 uint64_t instrlimit, uint64_t memlimit, nvpair_t *nvarg, nvlist_t *outnvl)
1039 zcp_eval_arg_t evalargs;
1041 if (instrlimit > zfs_lua_max_instrlimit)
1042 return (SET_ERROR(EINVAL));
1043 if (memlimit == 0 || memlimit > zfs_lua_max_memlimit)
1044 return (SET_ERROR(EINVAL));
1046 zcp_alloc_arg_t allocargs = {
1047 .aa_must_succeed = B_TRUE,
1048 .aa_alloc_remaining = (int64_t)memlimit,
1049 .aa_alloc_limit = (int64_t)memlimit,
1053 * Creates a Lua state with a memory allocator that uses KM_SLEEP.
1054 * This should never fail.
1056 state = lua_newstate(zcp_lua_alloc, &allocargs);
1057 VERIFY(state != NULL);
1058 (void) lua_atpanic(state, zcp_panic_cb);
1061 * Load core Lua libraries we want access to.
1063 VERIFY3U(1, ==, luaopen_base(state));
1065 VERIFY3U(1, ==, luaopen_coroutine(state));
1066 lua_setglobal(state, LUA_COLIBNAME);
1067 VERIFY0(lua_gettop(state));
1068 VERIFY3U(1, ==, luaopen_string(state));
1069 lua_setglobal(state, LUA_STRLIBNAME);
1070 VERIFY0(lua_gettop(state));
1071 VERIFY3U(1, ==, luaopen_table(state));
1072 lua_setglobal(state, LUA_TABLIBNAME);
1073 VERIFY0(lua_gettop(state));
1076 * Load globally visible variables such as errno aliases.
1078 zcp_load_globals(state);
1079 VERIFY0(lua_gettop(state));
1082 * Load ZFS-specific modules.
1084 lua_newtable(state);
1085 VERIFY3U(1, ==, zcp_load_list_lib(state));
1086 lua_setfield(state, -2, "list");
1087 VERIFY3U(1, ==, zcp_load_synctask_lib(state, B_FALSE));
1088 lua_setfield(state, -2, "check");
1089 VERIFY3U(1, ==, zcp_load_synctask_lib(state, B_TRUE));
1090 lua_setfield(state, -2, "sync");
1091 VERIFY3U(1, ==, zcp_load_get_lib(state));
1092 lua_pushcclosure(state, zcp_debug_info.func, 0);
1093 lua_setfield(state, -2, zcp_debug_info.name);
1094 lua_pushcclosure(state, zcp_exists_info.func, 0);
1095 lua_setfield(state, -2, zcp_exists_info.name);
1096 lua_setglobal(state, "zfs");
1097 VERIFY0(lua_gettop(state));
1100 * Push the error-callback that calculates Lua stack traces on
1101 * unexpected failures.
1103 lua_pushcfunction(state, zcp_error_handler);
1104 VERIFY3U(1, ==, lua_gettop(state));
1107 * Load the actual script as a function onto the stack as text ("t").
1108 * The only valid error condition is a syntax error in the script.
1109 * ERRMEM should not be possible because our allocator is using
1110 * KM_SLEEP. ERRGCMM should not be possible because we have not added
1111 * any objects with __gc metamethods to the interpreter that could
1114 err = luaL_loadbufferx(state, program, strlen(program),
1115 "channel program", "t");
1116 if (err == LUA_ERRSYNTAX) {
1117 fnvlist_add_string(outnvl, ZCP_RET_ERROR,
1118 lua_tostring(state, -1));
1120 return (SET_ERROR(EINVAL));
1123 VERIFY3U(2, ==, lua_gettop(state));
1126 * Convert the input nvlist to a Lua object and put it on top of the
1130 err = zcp_nvpair_value_to_lua(state, nvarg,
1131 errmsg, sizeof (errmsg));
1133 fnvlist_add_string(outnvl, ZCP_RET_ERROR, errmsg);
1135 return (SET_ERROR(EINVAL));
1137 VERIFY3U(3, ==, lua_gettop(state));
1139 evalargs.ea_state = state;
1140 evalargs.ea_allocargs = &allocargs;
1141 evalargs.ea_instrlimit = instrlimit;
1142 evalargs.ea_cred = CRED();
1143 evalargs.ea_outnvl = outnvl;
1144 evalargs.ea_result = 0;
1147 err = dsl_sync_task(poolname, NULL,
1148 zcp_eval_sync, &evalargs, 0, ZFS_SPACE_CHECK_ZCP_EVAL);
1150 zcp_pool_error(&evalargs, poolname);
1152 zcp_eval_open(&evalargs, poolname);
1156 return (evalargs.ea_result);
1160 * Retrieve metadata about the currently running channel program.
1163 zcp_run_info(lua_State *state)
1167 lua_getfield(state, LUA_REGISTRYINDEX, ZCP_RUN_INFO_KEY);
1168 ri = lua_touserdata(state, -1);
1177 * The Lua language allows methods to be called with any number
1178 * of arguments of any type. When calling back into ZFS we need to sanitize
1179 * arguments from channel programs to make sure unexpected arguments or
1180 * arguments of the wrong type result in clear error messages. To do this
1181 * in a uniform way all callbacks from channel programs should use the
1182 * zcp_parse_args() function to interpret inputs.
1184 * Positional vs Keyword Arguments
1185 * ===============================
1187 * Every callback function takes a fixed set of required positional arguments
1188 * and optional keyword arguments. For example, the destroy function takes
1189 * a single positional string argument (the name of the dataset to destroy)
1190 * and an optional "defer" keyword boolean argument. When calling lua functions
1191 * with parentheses, only positional arguments can be used:
1193 * zfs.sync.snapshot("rpool@snap")
1195 * To use keyword arguments functions should be called with a single argument
1196 * that is a lua table containing mappings of integer -> positional arguments
1197 * and string -> keyword arguments:
1199 * zfs.sync.snapshot({1="rpool@snap", defer=true})
1201 * The lua language allows curly braces to be used in place of parenthesis as
1202 * syntactic sugar for this calling convention:
1204 * zfs.sync.snapshot{"rpool@snap", defer=true}
1208 * Throw an error and print the given arguments. If there are too many
1209 * arguments to fit in the output buffer, only the error format string is
1213 zcp_args_error(lua_State *state, const char *fname, const zcp_arg_t *pargs,
1214 const zcp_arg_t *kwargs, const char *fmt, ...)
1218 size_t len = sizeof (errmsg);
1222 va_start(argp, fmt);
1223 VERIFY3U(len, >, vsnprintf(errmsg, len, fmt, argp));
1227 * Calculate the total length of the final string, including extra
1228 * formatting characters. If the argument dump would be too large,
1229 * only print the error string.
1231 msglen = strlen(errmsg);
1232 msglen += strlen(fname) + 4; /* : + {} + null terminator */
1233 for (i = 0; pargs[i].za_name != NULL; i++) {
1234 msglen += strlen(pargs[i].za_name);
1235 msglen += strlen(lua_typename(state, pargs[i].za_lua_type));
1236 if (pargs[i + 1].za_name != NULL || kwargs[0].za_name != NULL)
1237 msglen += 5; /* < + ( + )> + , */
1239 msglen += 4; /* < + ( + )> */
1241 for (i = 0; kwargs[i].za_name != NULL; i++) {
1242 msglen += strlen(kwargs[i].za_name);
1243 msglen += strlen(lua_typename(state, kwargs[i].za_lua_type));
1244 if (kwargs[i + 1].za_name != NULL)
1245 msglen += 4; /* =( + ) + , */
1247 msglen += 3; /* =( + ) */
1251 (void) luaL_error(state, errmsg);
1253 VERIFY3U(len, >, strlcat(errmsg, ": ", len));
1254 VERIFY3U(len, >, strlcat(errmsg, fname, len));
1255 VERIFY3U(len, >, strlcat(errmsg, "{", len));
1256 for (i = 0; pargs[i].za_name != NULL; i++) {
1257 VERIFY3U(len, >, strlcat(errmsg, "<", len));
1258 VERIFY3U(len, >, strlcat(errmsg, pargs[i].za_name, len));
1259 VERIFY3U(len, >, strlcat(errmsg, "(", len));
1260 VERIFY3U(len, >, strlcat(errmsg,
1261 lua_typename(state, pargs[i].za_lua_type), len));
1262 VERIFY3U(len, >, strlcat(errmsg, ")>", len));
1263 if (pargs[i + 1].za_name != NULL || kwargs[0].za_name != NULL) {
1264 VERIFY3U(len, >, strlcat(errmsg, ", ", len));
1267 for (i = 0; kwargs[i].za_name != NULL; i++) {
1268 VERIFY3U(len, >, strlcat(errmsg, kwargs[i].za_name, len));
1269 VERIFY3U(len, >, strlcat(errmsg, "=(", len));
1270 VERIFY3U(len, >, strlcat(errmsg,
1271 lua_typename(state, kwargs[i].za_lua_type), len));
1272 VERIFY3U(len, >, strlcat(errmsg, ")", len));
1273 if (kwargs[i + 1].za_name != NULL) {
1274 VERIFY3U(len, >, strlcat(errmsg, ", ", len));
1277 VERIFY3U(len, >, strlcat(errmsg, "}", len));
1279 (void) luaL_error(state, errmsg);
1280 panic("unreachable code");
1284 zcp_parse_table_args(lua_State *state, const char *fname,
1285 const zcp_arg_t *pargs, const zcp_arg_t *kwargs)
1290 for (i = 0; pargs[i].za_name != NULL; i++) {
1292 * Check the table for this positional argument, leaving it
1293 * on the top of the stack once we finish validating it.
1295 lua_pushinteger(state, i + 1);
1296 lua_gettable(state, 1);
1298 type = lua_type(state, -1);
1299 if (type == LUA_TNIL) {
1300 zcp_args_error(state, fname, pargs, kwargs,
1301 "too few arguments");
1302 panic("unreachable code");
1303 } else if (type != pargs[i].za_lua_type) {
1304 zcp_args_error(state, fname, pargs, kwargs,
1305 "arg %d wrong type (is '%s', expected '%s')",
1306 i + 1, lua_typename(state, type),
1307 lua_typename(state, pargs[i].za_lua_type));
1308 panic("unreachable code");
1312 * Remove the positional argument from the table.
1314 lua_pushinteger(state, i + 1);
1316 lua_settable(state, 1);
1319 for (i = 0; kwargs[i].za_name != NULL; i++) {
1321 * Check the table for this keyword argument, which may be
1322 * nil if it was omitted. Leave the value on the top of
1323 * the stack after validating it.
1325 lua_getfield(state, 1, kwargs[i].za_name);
1327 type = lua_type(state, -1);
1328 if (type != LUA_TNIL && type != kwargs[i].za_lua_type) {
1329 zcp_args_error(state, fname, pargs, kwargs,
1330 "kwarg '%s' wrong type (is '%s', expected '%s')",
1331 kwargs[i].za_name, lua_typename(state, type),
1332 lua_typename(state, kwargs[i].za_lua_type));
1333 panic("unreachable code");
1337 * Remove the keyword argument from the table.
1340 lua_setfield(state, 1, kwargs[i].za_name);
1344 * Any entries remaining in the table are invalid inputs, print
1345 * an error message based on what the entry is.
1348 if (lua_next(state, 1)) {
1349 if (lua_isnumber(state, -2) && lua_tointeger(state, -2) > 0) {
1350 zcp_args_error(state, fname, pargs, kwargs,
1351 "too many positional arguments");
1352 } else if (lua_isstring(state, -2)) {
1353 zcp_args_error(state, fname, pargs, kwargs,
1354 "invalid kwarg '%s'", lua_tostring(state, -2));
1356 zcp_args_error(state, fname, pargs, kwargs,
1357 "kwarg keys must be strings");
1359 panic("unreachable code");
1362 lua_remove(state, 1);
1366 zcp_parse_pos_args(lua_State *state, const char *fname, const zcp_arg_t *pargs,
1367 const zcp_arg_t *kwargs)
1372 for (i = 0; pargs[i].za_name != NULL; i++) {
1373 type = lua_type(state, i + 1);
1374 if (type == LUA_TNONE) {
1375 zcp_args_error(state, fname, pargs, kwargs,
1376 "too few arguments");
1377 panic("unreachable code");
1378 } else if (type != pargs[i].za_lua_type) {
1379 zcp_args_error(state, fname, pargs, kwargs,
1380 "arg %d wrong type (is '%s', expected '%s')",
1381 i + 1, lua_typename(state, type),
1382 lua_typename(state, pargs[i].za_lua_type));
1383 panic("unreachable code");
1386 if (lua_gettop(state) != i) {
1387 zcp_args_error(state, fname, pargs, kwargs,
1388 "too many positional arguments");
1389 panic("unreachable code");
1392 for (i = 0; kwargs[i].za_name != NULL; i++) {
1398 * Checks the current Lua stack against an expected set of positional and
1399 * keyword arguments. If the stack does not match the expected arguments
1400 * aborts the current channel program with a useful error message, otherwise
1401 * it re-arranges the stack so that it contains the positional arguments
1402 * followed by the keyword argument values in declaration order. Any missing
1403 * keyword argument will be represented by a nil value on the stack.
1405 * If the stack contains exactly one argument of type LUA_TTABLE the curly
1406 * braces calling convention is assumed, otherwise the stack is parsed for
1407 * positional arguments only.
1409 * This function should be used by every function callback. It should be called
1410 * before the callback manipulates the Lua stack as it assumes the stack
1411 * represents the function arguments.
1414 zcp_parse_args(lua_State *state, const char *fname, const zcp_arg_t *pargs,
1415 const zcp_arg_t *kwargs)
1417 if (lua_gettop(state) == 1 && lua_istable(state, 1)) {
1418 zcp_parse_table_args(state, fname, pargs, kwargs);
1420 zcp_parse_pos_args(state, fname, pargs, kwargs);
1424 #if defined(_KERNEL)
1426 module_param(zfs_lua_max_instrlimit, ulong, 0644);
1427 MODULE_PARM_DESC(zfs_lua_max_instrlimit,
1428 "Max instruction limit that can be specified for a channel program");
1430 module_param(zfs_lua_max_memlimit, ulong, 0644);
1431 MODULE_PARM_DESC(zfs_lua_max_memlimit,
1432 "Max memory limit that can be specified for a channel program");