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Commit | Line | Data |
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a54d5262 DW |
1 | /* |
2 | * mdmon - monitor external metadata arrays | |
3 | * | |
e736b623 N |
4 | * Copyright (C) 2007-2009 Neil Brown <neilb@suse.de> |
5 | * Copyright (C) 2007-2009 Intel Corporation | |
a54d5262 DW |
6 | * |
7 | * This program is free software; you can redistribute it and/or modify it | |
8 | * under the terms and conditions of the GNU General Public License, | |
9 | * version 2, as published by the Free Software Foundation. | |
10 | * | |
11 | * This program is distributed in the hope it will be useful, but WITHOUT | |
12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
14 | * more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License along with | |
17 | * this program; if not, write to the Free Software Foundation, Inc., | |
18 | * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. | |
19 | */ | |
549e9569 NB |
20 | |
21 | /* | |
22 | * md array manager. | |
23 | * When md arrays have user-space managed metadata, this is the program | |
24 | * that does the managing. | |
25 | * | |
26 | * Given one argument: the name of the array (e.g. /dev/md0) that is | |
27 | * the container. | |
28 | * We fork off a helper that runs high priority and mlocked. It responds to | |
29 | * device failures and other events that might stop writeout, or that are | |
30 | * trivial to deal with. | |
31 | * The main thread then watches for new arrays being created in the container | |
32 | * and starts monitoring them too ... along with a few other tasks. | |
33 | * | |
34 | * The main thread communicates with the priority thread by writing over | |
35 | * a pipe. | |
36 | * Separate programs can communicate with the main thread via Unix-domain | |
37 | * socket. | |
38 | * The two threads share address space and open file table. | |
39 | * | |
40 | */ | |
41 | ||
42 | #ifndef _GNU_SOURCE | |
43 | #define _GNU_SOURCE | |
44 | #endif | |
45 | ||
46 | #include <unistd.h> | |
47 | #include <stdlib.h> | |
4d43913c | 48 | #include <sys/types.h> |
549e9569 NB |
49 | #include <sys/stat.h> |
50 | #include <sys/socket.h> | |
51 | #include <sys/un.h> | |
52 | #include <sys/mman.h> | |
4d43913c | 53 | #include <sys/syscall.h> |
9fe32043 | 54 | #include <sys/wait.h> |
549e9569 NB |
55 | #include <stdio.h> |
56 | #include <errno.h> | |
57 | #include <string.h> | |
58 | #include <fcntl.h> | |
b109d928 | 59 | #include <signal.h> |
13047e4c | 60 | #include <dirent.h> |
f4190c2f DW |
61 | #ifdef USE_PTHREADS |
62 | #include <pthread.h> | |
63 | #else | |
549e9569 | 64 | #include <sched.h> |
f4190c2f | 65 | #endif |
549e9569 NB |
66 | |
67 | #include "mdadm.h" | |
68 | #include "mdmon.h" | |
69 | ||
549e9569 NB |
70 | struct active_array *discard_this; |
71 | struct active_array *pending_discard; | |
4d43913c NB |
72 | |
73 | int mon_tid, mgr_tid; | |
549e9569 | 74 | |
6144ed44 DW |
75 | int sigterm; |
76 | ||
f4190c2f DW |
77 | #ifdef USE_PTHREADS |
78 | static void *run_child(void *v) | |
79 | { | |
80 | struct supertype *c = v; | |
81 | ||
82 | mon_tid = syscall(SYS_gettid); | |
83 | do_monitor(c); | |
84 | return 0; | |
85 | } | |
86 | ||
87 | static int clone_monitor(struct supertype *container) | |
88 | { | |
89 | pthread_attr_t attr; | |
90 | pthread_t thread; | |
91 | int rc; | |
92 | ||
93 | mon_tid = -1; | |
94 | pthread_attr_init(&attr); | |
95 | pthread_attr_setstacksize(&attr, 4096); | |
96 | pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); | |
97 | rc = pthread_create(&thread, &attr, run_child, container); | |
98 | if (rc) | |
99 | return rc; | |
100 | while (mon_tid == -1) | |
101 | usleep(10); | |
102 | pthread_attr_destroy(&attr); | |
103 | ||
104 | mgr_tid = syscall(SYS_gettid); | |
105 | ||
106 | return mon_tid; | |
107 | } | |
108 | #else /* USE_PTHREADS */ | |
109 | static int run_child(void *v) | |
549e9569 NB |
110 | { |
111 | struct supertype *c = v; | |
1ed3f387 | 112 | |
549e9569 NB |
113 | do_monitor(c); |
114 | return 0; | |
115 | } | |
116 | ||
97f734fd N |
117 | #ifdef __ia64__ |
118 | int __clone2(int (*fn)(void *), | |
119 | void *child_stack_base, size_t stack_size, | |
120 | int flags, void *arg, ... | |
121 | /* pid_t *pid, struct user_desc *tls, pid_t *ctid */ ); | |
122 | #endif | |
f4190c2f | 123 | static int clone_monitor(struct supertype *container) |
549e9569 | 124 | { |
549e9569 | 125 | static char stack[4096]; |
549e9569 | 126 | |
97f734fd N |
127 | #ifdef __ia64__ |
128 | mon_tid = __clone2(run_child, stack, sizeof(stack), | |
129 | CLONE_FS|CLONE_FILES|CLONE_VM|CLONE_SIGHAND|CLONE_THREAD, | |
130 | container); | |
131 | #else | |
2cc98f9e | 132 | mon_tid = clone(run_child, stack+4096-64, |
549e9569 NB |
133 | CLONE_FS|CLONE_FILES|CLONE_VM|CLONE_SIGHAND|CLONE_THREAD, |
134 | container); | |
97f734fd | 135 | #endif |
3e70c845 | 136 | |
4d43913c | 137 | mgr_tid = syscall(SYS_gettid); |
2cc98f9e DW |
138 | |
139 | return mon_tid; | |
549e9569 | 140 | } |
f4190c2f | 141 | #endif /* USE_PTHREADS */ |
549e9569 | 142 | |
fa716c83 | 143 | static int make_pidfile(char *devname) |
549e9569 NB |
144 | { |
145 | char path[100]; | |
146 | char pid[10]; | |
147 | int fd; | |
3d2c4fc7 DW |
148 | int n; |
149 | ||
753cf905 | 150 | if (mkdir(MDMON_DIR, 0755) < 0 && |
ed8fa52f LB |
151 | errno != EEXIST) |
152 | return -errno; | |
753cf905 | 153 | sprintf(path, "%s/%s.pid", MDMON_DIR, devname); |
549e9569 | 154 | |
5d4d1b26 | 155 | fd = open(path, O_RDWR|O_CREAT|O_EXCL, 0600); |
549e9569 | 156 | if (fd < 0) |
295646b3 | 157 | return -errno; |
549e9569 | 158 | sprintf(pid, "%d\n", getpid()); |
3d2c4fc7 | 159 | n = write(fd, pid, strlen(pid)); |
549e9569 | 160 | close(fd); |
3d2c4fc7 DW |
161 | if (n < 0) |
162 | return -errno; | |
549e9569 NB |
163 | return 0; |
164 | } | |
165 | ||
9f1da824 | 166 | static void try_kill_monitor(pid_t pid, char *devname, int sock) |
96a8270d DW |
167 | { |
168 | char buf[100]; | |
169 | int fd; | |
417a4b04 | 170 | int n; |
af7ca334 | 171 | long fl; |
b109d928 | 172 | |
8aae4219 DW |
173 | /* first rule of survival... don't off yourself */ |
174 | if (pid == getpid()) | |
175 | return; | |
176 | ||
b109d928 DW |
177 | /* kill this process if it is mdmon */ |
178 | sprintf(buf, "/proc/%lu/cmdline", (unsigned long) pid); | |
179 | fd = open(buf, O_RDONLY); | |
180 | if (fd < 0) | |
181 | return; | |
182 | ||
417a4b04 N |
183 | n = read(fd, buf, sizeof(buf)-1); |
184 | buf[sizeof(buf)-1] = 0; | |
185 | close(fd); | |
b109d928 | 186 | |
417a4b04 | 187 | if (n < 0 || !strstr(buf, "mdmon")) |
883a6142 DW |
188 | return; |
189 | ||
190 | kill(pid, SIGTERM); | |
191 | ||
af7ca334 N |
192 | /* Wait for monitor to exit by reading from the socket, after |
193 | * clearing the non-blocking flag */ | |
194 | fl = fcntl(sock, F_GETFL, 0); | |
195 | fl &= ~O_NONBLOCK; | |
196 | fcntl(sock, F_SETFL, fl); | |
fcf57625 N |
197 | n = read(sock, buf, 100); |
198 | /* Ignore result, it is just the wait that | |
199 | * matters | |
200 | */ | |
b109d928 DW |
201 | } |
202 | ||
e0d6609f NB |
203 | void remove_pidfile(char *devname) |
204 | { | |
205 | char buf[100]; | |
206 | ||
753cf905 | 207 | sprintf(buf, "%s/%s.pid", MDMON_DIR, devname); |
e0d6609f | 208 | unlink(buf); |
753cf905 | 209 | sprintf(buf, "%s/%s.sock", MDMON_DIR, devname); |
57752795 | 210 | unlink(buf); |
e0d6609f NB |
211 | } |
212 | ||
fa716c83 | 213 | static int make_control_sock(char *devname) |
549e9569 NB |
214 | { |
215 | char path[100]; | |
216 | int sfd; | |
217 | long fl; | |
218 | struct sockaddr_un addr; | |
219 | ||
6144ed44 DW |
220 | if (sigterm) |
221 | return -1; | |
222 | ||
753cf905 | 223 | sprintf(path, "%s/%s.sock", MDMON_DIR, devname); |
549e9569 NB |
224 | unlink(path); |
225 | sfd = socket(PF_LOCAL, SOCK_STREAM, 0); | |
226 | if (sfd < 0) | |
227 | return -1; | |
228 | ||
229 | addr.sun_family = PF_LOCAL; | |
230 | strcpy(addr.sun_path, path); | |
231 | if (bind(sfd, &addr, sizeof(addr)) < 0) { | |
232 | close(sfd); | |
233 | return -1; | |
234 | } | |
235 | listen(sfd, 10); | |
236 | fl = fcntl(sfd, F_GETFL, 0); | |
237 | fl |= O_NONBLOCK; | |
238 | fcntl(sfd, F_SETFL, fl); | |
239 | return sfd; | |
240 | } | |
241 | ||
6144ed44 DW |
242 | static void term(int sig) |
243 | { | |
244 | sigterm = 1; | |
245 | } | |
246 | ||
4d43913c NB |
247 | static void wake_me(int sig) |
248 | { | |
249 | ||
250 | } | |
251 | ||
16ddab0d DW |
252 | /* if we are debugging and starting mdmon by hand then don't fork */ |
253 | static int do_fork(void) | |
254 | { | |
255 | #ifdef DEBUG | |
40ebbb9c | 256 | if (check_env("MDADM_NO_MDMON")) |
16ddab0d DW |
257 | return 0; |
258 | #endif | |
259 | ||
260 | return 1; | |
261 | } | |
262 | ||
13047e4c DW |
263 | void usage(void) |
264 | { | |
eb49460b | 265 | fprintf(stderr, "Usage: mdmon [--all] [--takeover] CONTAINER\n"); |
13047e4c DW |
266 | exit(2); |
267 | } | |
16ddab0d | 268 | |
b5c727dc | 269 | static int mdmon(char *devname, int devnum, int must_fork, int takeover); |
1ffd2840 | 270 | |
549e9569 NB |
271 | int main(int argc, char *argv[]) |
272 | { | |
13047e4c | 273 | char *container_name = NULL; |
e8a70c89 N |
274 | int devnum; |
275 | char *devname; | |
1ffd2840 | 276 | int status = 0; |
b5c727dc N |
277 | int arg; |
278 | int all = 0; | |
279 | int takeover = 0; | |
280 | ||
281 | for (arg = 1; arg < argc; arg++) { | |
eb49460b LB |
282 | if (strncmp(argv[arg], "--all",5) == 0 || |
283 | strcmp(argv[arg], "/proc/mdstat") == 0) { | |
284 | container_name = argv[arg]; | |
b5c727dc | 285 | all = 1; |
eb49460b | 286 | } else if (strcmp(argv[arg], "--takeover") == 0) |
b5c727dc N |
287 | takeover = 1; |
288 | else if (container_name == NULL) | |
289 | container_name = argv[arg]; | |
290 | else | |
291 | usage(); | |
549e9569 | 292 | } |
eb49460b LB |
293 | if (container_name == NULL) |
294 | usage(); | |
13047e4c | 295 | |
b5c727dc | 296 | if (all) { |
1ffd2840 | 297 | struct mdstat_ent *mdstat, *e; |
eb49460b | 298 | int container_len = strlen(container_name); |
1ffd2840 DW |
299 | |
300 | /* launch an mdmon instance for each container found */ | |
1ffd2840 DW |
301 | mdstat = mdstat_read(0, 0); |
302 | for (e = mdstat; e; e = e->next) { | |
f4db7a6f MM |
303 | if (e->metadata_version && |
304 | strncmp(e->metadata_version, "external:", 9) == 0 && | |
1ffd2840 DW |
305 | !is_subarray(&e->metadata_version[9])) { |
306 | devname = devnum2devname(e->devnum); | |
1b34f519 DW |
307 | /* update cmdline so this mdmon instance can be |
308 | * distinguished from others in a call to ps(1) | |
309 | */ | |
f21e18ca | 310 | if (strlen(devname) <= (unsigned)container_len) { |
eb49460b | 311 | memset(container_name, 0, container_len); |
1b34f519 DW |
312 | sprintf(container_name, "%s", devname); |
313 | } | |
3e7312a9 | 314 | status |= mdmon(devname, e->devnum, 1, |
b5c727dc | 315 | takeover); |
1ffd2840 DW |
316 | } |
317 | } | |
318 | free_mdstat(mdstat); | |
319 | ||
320 | return status; | |
321 | } else if (strncmp(container_name, "md", 2) == 0) { | |
6f4098a6 DW |
322 | devnum = devname2devnum(container_name); |
323 | devname = devnum2devname(devnum); | |
324 | if (strcmp(container_name, devname) != 0) | |
325 | devname = NULL; | |
326 | } else { | |
327 | struct stat st; | |
328 | ||
329 | devnum = NoMdDev; | |
330 | if (stat(container_name, &st) == 0) | |
331 | devnum = stat2devnum(&st); | |
332 | if (devnum == NoMdDev) | |
333 | devname = NULL; | |
334 | else | |
335 | devname = devnum2devname(devnum); | |
336 | } | |
337 | ||
338 | if (!devname) { | |
e8a70c89 N |
339 | fprintf(stderr, "mdmon: %s is not a valid md device name\n", |
340 | container_name); | |
341 | exit(1); | |
342 | } | |
b5c727dc | 343 | return mdmon(devname, devnum, do_fork(), takeover); |
1ffd2840 DW |
344 | } |
345 | ||
b5c727dc | 346 | static int mdmon(char *devname, int devnum, int must_fork, int takeover) |
1ffd2840 DW |
347 | { |
348 | int mdfd; | |
349 | struct mdinfo *mdi, *di; | |
350 | struct supertype *container; | |
351 | sigset_t set; | |
352 | struct sigaction act; | |
353 | int pfd[2]; | |
354 | int status; | |
355 | int ignore; | |
96a8270d | 356 | pid_t victim = -1; |
9f1da824 | 357 | int victim_sock = -1; |
1ffd2840 | 358 | |
b5c727dc | 359 | dprintf("starting mdmon for %s\n", devname); |
b928b5a0 | 360 | |
e8a70c89 | 361 | mdfd = open_dev(devnum); |
549e9569 | 362 | if (mdfd < 0) { |
1ffd2840 | 363 | fprintf(stderr, "mdmon: %s: %s\n", devname, |
549e9569 | 364 | strerror(errno)); |
1ffd2840 | 365 | return 1; |
549e9569 NB |
366 | } |
367 | if (md_get_version(mdfd) < 0) { | |
13047e4c | 368 | fprintf(stderr, "mdmon: %s: Not an md device\n", |
1ffd2840 DW |
369 | devname); |
370 | return 1; | |
549e9569 NB |
371 | } |
372 | ||
9fe32043 | 373 | /* Fork, and have the child tell us when they are ready */ |
3e7312a9 | 374 | if (must_fork) { |
3d2c4fc7 DW |
375 | if (pipe(pfd) != 0) { |
376 | fprintf(stderr, "mdmon: failed to create pipe\n"); | |
1ffd2840 | 377 | return 1; |
3d2c4fc7 | 378 | } |
16ddab0d DW |
379 | switch(fork()) { |
380 | case -1: | |
381 | fprintf(stderr, "mdmon: failed to fork: %s\n", | |
382 | strerror(errno)); | |
1ffd2840 | 383 | return 1; |
16ddab0d DW |
384 | case 0: /* child */ |
385 | close(pfd[0]); | |
386 | break; | |
387 | default: /* parent */ | |
388 | close(pfd[1]); | |
389 | if (read(pfd[0], &status, sizeof(status)) != sizeof(status)) { | |
390 | wait(&status); | |
391 | status = WEXITSTATUS(status); | |
392 | } | |
1ffd2840 | 393 | return status; |
9fe32043 | 394 | } |
16ddab0d DW |
395 | } else |
396 | pfd[0] = pfd[1] = -1; | |
549e9569 | 397 | |
f5df5d69 | 398 | container = calloc(1, sizeof(*container)); |
e8a70c89 N |
399 | container->devnum = devnum; |
400 | container->devname = devname; | |
13047e4c | 401 | container->arrays = NULL; |
96a8270d | 402 | container->sock = -1; |
13047e4c DW |
403 | |
404 | if (!container->devname) { | |
405 | fprintf(stderr, "mdmon: failed to allocate container name string\n"); | |
406 | exit(3); | |
407 | } | |
408 | ||
b526e52d | 409 | mdi = sysfs_read(mdfd, container->devnum, GET_VERSION|GET_LEVEL|GET_DEVS); |
13047e4c DW |
410 | |
411 | if (!mdi) { | |
412 | fprintf(stderr, "mdmon: failed to load sysfs info for %s\n", | |
413 | container->devname); | |
414 | exit(3); | |
415 | } | |
416 | if (mdi->array.level != UnSet) { | |
417 | fprintf(stderr, "mdmon: %s is not a container - cannot monitor\n", | |
1ffd2840 | 418 | devname); |
13047e4c DW |
419 | exit(3); |
420 | } | |
421 | if (mdi->array.major_version != -1 || | |
422 | mdi->array.minor_version != -2) { | |
423 | fprintf(stderr, "mdmon: %s does not use external metadata - cannot monitor\n", | |
1ffd2840 | 424 | devname); |
13047e4c DW |
425 | exit(3); |
426 | } | |
427 | ||
33414a01 | 428 | container->ss = version_to_superswitch(mdi->text_version); |
13047e4c | 429 | if (container->ss == NULL) { |
33414a01 | 430 | fprintf(stderr, "mdmon: %s uses unsupported metadata: %s\n", |
1ffd2840 | 431 | devname, mdi->text_version); |
13047e4c DW |
432 | exit(3); |
433 | } | |
434 | ||
435 | container->devs = NULL; | |
436 | for (di = mdi->devs; di; di = di->next) { | |
437 | struct mdinfo *cd = malloc(sizeof(*cd)); | |
438 | *cd = *di; | |
439 | cd->next = container->devs; | |
440 | container->devs = cd; | |
441 | } | |
442 | sysfs_free(mdi); | |
549e9569 | 443 | |
883a6142 DW |
444 | /* SIGUSR is sent between parent and child. So both block it |
445 | * and enable it only with pselect. | |
446 | */ | |
447 | sigemptyset(&set); | |
448 | sigaddset(&set, SIGUSR1); | |
883a6142 DW |
449 | sigaddset(&set, SIGTERM); |
450 | sigprocmask(SIG_BLOCK, &set, NULL); | |
451 | act.sa_handler = wake_me; | |
452 | act.sa_flags = 0; | |
453 | sigaction(SIGUSR1, &act, NULL); | |
883a6142 DW |
454 | act.sa_handler = term; |
455 | sigaction(SIGTERM, &act, NULL); | |
456 | act.sa_handler = SIG_IGN; | |
457 | sigaction(SIGPIPE, &act, NULL); | |
458 | ||
32f21701 | 459 | victim = mdmon_pid(container->devnum); |
32f21701 N |
460 | if (victim >= 0) |
461 | victim_sock = connect_monitor(container->devname); | |
13047e4c | 462 | |
13047e4c | 463 | ignore = chdir("/"); |
32f21701 N |
464 | if (!takeover && victim > 0 && victim_sock >= 0) { |
465 | if (fping_monitor(victim_sock) == 0) { | |
b109d928 DW |
466 | fprintf(stderr, "mdmon: %s already managed\n", |
467 | container->devname); | |
468 | exit(3); | |
24cfdbc5 | 469 | } |
32f21701 | 470 | close(victim_sock); |
549e9569 | 471 | } |
0fb69d1d | 472 | if (container->ss->load_container(container, mdfd, devname)) { |
549e9569 | 473 | fprintf(stderr, "mdmon: Cannot load metadata for %s\n", |
1ffd2840 | 474 | devname); |
549e9569 NB |
475 | exit(3); |
476 | } | |
e8a70c89 | 477 | close(mdfd); |
549e9569 | 478 | |
9fe32043 N |
479 | /* Ok, this is close enough. We can say goodbye to our parent now. |
480 | */ | |
fa716c83 N |
481 | if (victim > 0) |
482 | remove_pidfile(devname); | |
fa716c83 | 483 | if (make_pidfile(devname) < 0) { |
753cf905 | 484 | exit(3); |
fa716c83 N |
485 | } |
486 | container->sock = make_control_sock(devname); | |
487 | ||
9fe32043 | 488 | status = 0; |
3d2c4fc7 DW |
489 | if (write(pfd[1], &status, sizeof(status)) < 0) |
490 | fprintf(stderr, "mdmon: failed to notify our parent: %d\n", | |
491 | getppid()); | |
9fe32043 N |
492 | close(pfd[1]); |
493 | ||
1373b07d | 494 | mlockall(MCL_CURRENT | MCL_FUTURE); |
549e9569 | 495 | |
3e70c845 | 496 | if (clone_monitor(container) < 0) { |
295646b3 | 497 | fprintf(stderr, "mdmon: failed to start monitor process: %s\n", |
549e9569 NB |
498 | strerror(errno)); |
499 | exit(2); | |
500 | } | |
501 | ||
fa716c83 | 502 | if (victim > 0) { |
9f1da824 DW |
503 | try_kill_monitor(victim, container->devname, victim_sock); |
504 | close(victim_sock); | |
505 | } | |
e98ef225 N |
506 | |
507 | setsid(); | |
508 | close(0); | |
509 | open("/dev/null", O_RDWR); | |
510 | close(1); | |
511 | ignore = dup(0); | |
512 | #ifndef DEBUG | |
513 | close(2); | |
514 | ignore = dup(0); | |
515 | #endif | |
516 | ||
e4c72d1d LB |
517 | /* This silliness is to stop the compiler complaining |
518 | * that we ignore 'ignore' | |
519 | */ | |
520 | if (ignore) | |
521 | ignore++; | |
522 | ||
549e9569 NB |
523 | do_manager(container); |
524 | ||
525 | exit(0); | |
526 | } | |
999b4972 N |
527 | |
528 | /* Some stub functions so super-* can link with us */ | |
529 | int child_monitor(int afd, struct mdinfo *sra, struct reshape *reshape, | |
530 | struct supertype *st, unsigned long blocks, | |
531 | int *fds, unsigned long long *offsets, | |
532 | int dests, int *destfd, unsigned long long *destoffsets) | |
533 | { | |
534 | return 0; | |
535 | } | |
afbbf073 AK |
536 | |
537 | int restore_stripes(int *dest, unsigned long long *offsets, | |
538 | int raid_disks, int chunk_size, int level, int layout, | |
539 | int source, unsigned long long read_offset, | |
540 | unsigned long long start, unsigned long long length, | |
541 | char *src_buf) | |
542 | { | |
543 | return 1; | |
544 | } | |
545 | ||
546 | void abort_reshape(struct mdinfo *sra) | |
547 | { | |
548 | return; | |
549 | } | |
550 | ||
551 | int save_stripes(int *source, unsigned long long *offsets, | |
552 | int raid_disks, int chunk_size, int level, int layout, | |
553 | int nwrites, int *dest, | |
554 | unsigned long long start, unsigned long long length, | |
555 | char *buf) | |
556 | { | |
557 | return 0; | |
558 | } |