| 1 | /* |
| 2 | * linux/fs/lockd/svclock.c |
| 3 | * |
| 4 | * Handling of server-side locks, mostly of the blocked variety. |
| 5 | * This is the ugliest part of lockd because we tread on very thin ice. |
| 6 | * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc. |
| 7 | * IMNSHO introducing the grant callback into the NLM protocol was one |
| 8 | * of the worst ideas Sun ever had. Except maybe for the idea of doing |
| 9 | * NFS file locking at all. |
| 10 | * |
| 11 | * I'm trying hard to avoid race conditions by protecting most accesses |
| 12 | * to a file's list of blocked locks through a semaphore. The global |
| 13 | * list of blocked locks is not protected in this fashion however. |
| 14 | * Therefore, some functions (such as the RPC callback for the async grant |
| 15 | * call) move blocked locks towards the head of the list *while some other |
| 16 | * process might be traversing it*. This should not be a problem in |
| 17 | * practice, because this will only cause functions traversing the list |
| 18 | * to visit some blocks twice. |
| 19 | * |
| 20 | * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de> |
| 21 | */ |
| 22 | |
| 23 | #include <linux/types.h> |
| 24 | #include <linux/slab.h> |
| 25 | #include <linux/errno.h> |
| 26 | #include <linux/kernel.h> |
| 27 | #include <linux/sched.h> |
| 28 | #include <linux/sunrpc/clnt.h> |
| 29 | #include <linux/sunrpc/svc_xprt.h> |
| 30 | #include <linux/lockd/nlm.h> |
| 31 | #include <linux/lockd/lockd.h> |
| 32 | #include <linux/kthread.h> |
| 33 | |
| 34 | #define NLMDBG_FACILITY NLMDBG_SVCLOCK |
| 35 | |
| 36 | #ifdef CONFIG_LOCKD_V4 |
| 37 | #define nlm_deadlock nlm4_deadlock |
| 38 | #else |
| 39 | #define nlm_deadlock nlm_lck_denied |
| 40 | #endif |
| 41 | |
| 42 | static void nlmsvc_release_block(struct nlm_block *block); |
| 43 | static void nlmsvc_insert_block(struct nlm_block *block, unsigned long); |
| 44 | static void nlmsvc_remove_block(struct nlm_block *block); |
| 45 | |
| 46 | static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock); |
| 47 | static void nlmsvc_freegrantargs(struct nlm_rqst *call); |
| 48 | static const struct rpc_call_ops nlmsvc_grant_ops; |
| 49 | |
| 50 | /* |
| 51 | * The list of blocked locks to retry |
| 52 | */ |
| 53 | static LIST_HEAD(nlm_blocked); |
| 54 | static DEFINE_SPINLOCK(nlm_blocked_lock); |
| 55 | |
| 56 | #if IS_ENABLED(CONFIG_SUNRPC_DEBUG) |
| 57 | static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie) |
| 58 | { |
| 59 | /* |
| 60 | * We can get away with a static buffer because this is only called |
| 61 | * from lockd, which is single-threaded. |
| 62 | */ |
| 63 | static char buf[2*NLM_MAXCOOKIELEN+1]; |
| 64 | unsigned int i, len = sizeof(buf); |
| 65 | char *p = buf; |
| 66 | |
| 67 | len--; /* allow for trailing \0 */ |
| 68 | if (len < 3) |
| 69 | return "???"; |
| 70 | for (i = 0 ; i < cookie->len ; i++) { |
| 71 | if (len < 2) { |
| 72 | strcpy(p-3, "..."); |
| 73 | break; |
| 74 | } |
| 75 | sprintf(p, "%02x", cookie->data[i]); |
| 76 | p += 2; |
| 77 | len -= 2; |
| 78 | } |
| 79 | *p = '\0'; |
| 80 | |
| 81 | return buf; |
| 82 | } |
| 83 | #endif |
| 84 | |
| 85 | /* |
| 86 | * Insert a blocked lock into the global list |
| 87 | */ |
| 88 | static void |
| 89 | nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when) |
| 90 | { |
| 91 | struct nlm_block *b; |
| 92 | struct list_head *pos; |
| 93 | |
| 94 | dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when); |
| 95 | if (list_empty(&block->b_list)) { |
| 96 | kref_get(&block->b_count); |
| 97 | } else { |
| 98 | list_del_init(&block->b_list); |
| 99 | } |
| 100 | |
| 101 | pos = &nlm_blocked; |
| 102 | if (when != NLM_NEVER) { |
| 103 | if ((when += jiffies) == NLM_NEVER) |
| 104 | when ++; |
| 105 | list_for_each(pos, &nlm_blocked) { |
| 106 | b = list_entry(pos, struct nlm_block, b_list); |
| 107 | if (time_after(b->b_when,when) || b->b_when == NLM_NEVER) |
| 108 | break; |
| 109 | } |
| 110 | /* On normal exit from the loop, pos == &nlm_blocked, |
| 111 | * so we will be adding to the end of the list - good |
| 112 | */ |
| 113 | } |
| 114 | |
| 115 | list_add_tail(&block->b_list, pos); |
| 116 | block->b_when = when; |
| 117 | } |
| 118 | |
| 119 | static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when) |
| 120 | { |
| 121 | spin_lock(&nlm_blocked_lock); |
| 122 | nlmsvc_insert_block_locked(block, when); |
| 123 | spin_unlock(&nlm_blocked_lock); |
| 124 | } |
| 125 | |
| 126 | /* |
| 127 | * Remove a block from the global list |
| 128 | */ |
| 129 | static inline void |
| 130 | nlmsvc_remove_block(struct nlm_block *block) |
| 131 | { |
| 132 | if (!list_empty(&block->b_list)) { |
| 133 | spin_lock(&nlm_blocked_lock); |
| 134 | list_del_init(&block->b_list); |
| 135 | spin_unlock(&nlm_blocked_lock); |
| 136 | nlmsvc_release_block(block); |
| 137 | } |
| 138 | } |
| 139 | |
| 140 | /* |
| 141 | * Find a block for a given lock |
| 142 | */ |
| 143 | static struct nlm_block * |
| 144 | nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock) |
| 145 | { |
| 146 | struct nlm_block *block; |
| 147 | struct file_lock *fl; |
| 148 | |
| 149 | dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n", |
| 150 | file, lock->fl.fl_pid, |
| 151 | (long long)lock->fl.fl_start, |
| 152 | (long long)lock->fl.fl_end, lock->fl.fl_type); |
| 153 | list_for_each_entry(block, &nlm_blocked, b_list) { |
| 154 | fl = &block->b_call->a_args.lock.fl; |
| 155 | dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n", |
| 156 | block->b_file, fl->fl_pid, |
| 157 | (long long)fl->fl_start, |
| 158 | (long long)fl->fl_end, fl->fl_type, |
| 159 | nlmdbg_cookie2a(&block->b_call->a_args.cookie)); |
| 160 | if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) { |
| 161 | kref_get(&block->b_count); |
| 162 | return block; |
| 163 | } |
| 164 | } |
| 165 | |
| 166 | return NULL; |
| 167 | } |
| 168 | |
| 169 | static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b) |
| 170 | { |
| 171 | if (a->len != b->len) |
| 172 | return 0; |
| 173 | if (memcmp(a->data, b->data, a->len)) |
| 174 | return 0; |
| 175 | return 1; |
| 176 | } |
| 177 | |
| 178 | /* |
| 179 | * Find a block with a given NLM cookie. |
| 180 | */ |
| 181 | static inline struct nlm_block * |
| 182 | nlmsvc_find_block(struct nlm_cookie *cookie) |
| 183 | { |
| 184 | struct nlm_block *block; |
| 185 | |
| 186 | list_for_each_entry(block, &nlm_blocked, b_list) { |
| 187 | if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie)) |
| 188 | goto found; |
| 189 | } |
| 190 | |
| 191 | return NULL; |
| 192 | |
| 193 | found: |
| 194 | dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block); |
| 195 | kref_get(&block->b_count); |
| 196 | return block; |
| 197 | } |
| 198 | |
| 199 | /* |
| 200 | * Create a block and initialize it. |
| 201 | * |
| 202 | * Note: we explicitly set the cookie of the grant reply to that of |
| 203 | * the blocked lock request. The spec explicitly mentions that the client |
| 204 | * should _not_ rely on the callback containing the same cookie as the |
| 205 | * request, but (as I found out later) that's because some implementations |
| 206 | * do just this. Never mind the standards comittees, they support our |
| 207 | * logging industries. |
| 208 | * |
| 209 | * 10 years later: I hope we can safely ignore these old and broken |
| 210 | * clients by now. Let's fix this so we can uniquely identify an incoming |
| 211 | * GRANTED_RES message by cookie, without having to rely on the client's IP |
| 212 | * address. --okir |
| 213 | */ |
| 214 | static struct nlm_block * |
| 215 | nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host, |
| 216 | struct nlm_file *file, struct nlm_lock *lock, |
| 217 | struct nlm_cookie *cookie) |
| 218 | { |
| 219 | struct nlm_block *block; |
| 220 | struct nlm_rqst *call = NULL; |
| 221 | |
| 222 | call = nlm_alloc_call(host); |
| 223 | if (call == NULL) |
| 224 | return NULL; |
| 225 | |
| 226 | /* Allocate memory for block, and initialize arguments */ |
| 227 | block = kzalloc(sizeof(*block), GFP_KERNEL); |
| 228 | if (block == NULL) |
| 229 | goto failed; |
| 230 | kref_init(&block->b_count); |
| 231 | INIT_LIST_HEAD(&block->b_list); |
| 232 | INIT_LIST_HEAD(&block->b_flist); |
| 233 | |
| 234 | if (!nlmsvc_setgrantargs(call, lock)) |
| 235 | goto failed_free; |
| 236 | |
| 237 | /* Set notifier function for VFS, and init args */ |
| 238 | call->a_args.lock.fl.fl_flags |= FL_SLEEP; |
| 239 | call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations; |
| 240 | nlmclnt_next_cookie(&call->a_args.cookie); |
| 241 | |
| 242 | dprintk("lockd: created block %p...\n", block); |
| 243 | |
| 244 | /* Create and initialize the block */ |
| 245 | block->b_daemon = rqstp->rq_server; |
| 246 | block->b_host = host; |
| 247 | block->b_file = file; |
| 248 | file->f_count++; |
| 249 | |
| 250 | /* Add to file's list of blocks */ |
| 251 | list_add(&block->b_flist, &file->f_blocks); |
| 252 | |
| 253 | /* Set up RPC arguments for callback */ |
| 254 | block->b_call = call; |
| 255 | call->a_flags = RPC_TASK_ASYNC; |
| 256 | call->a_block = block; |
| 257 | |
| 258 | return block; |
| 259 | |
| 260 | failed_free: |
| 261 | kfree(block); |
| 262 | failed: |
| 263 | nlmsvc_release_call(call); |
| 264 | return NULL; |
| 265 | } |
| 266 | |
| 267 | /* |
| 268 | * Delete a block. |
| 269 | * It is the caller's responsibility to check whether the file |
| 270 | * can be closed hereafter. |
| 271 | */ |
| 272 | static int nlmsvc_unlink_block(struct nlm_block *block) |
| 273 | { |
| 274 | int status; |
| 275 | dprintk("lockd: unlinking block %p...\n", block); |
| 276 | |
| 277 | /* Remove block from list */ |
| 278 | status = posix_unblock_lock(&block->b_call->a_args.lock.fl); |
| 279 | nlmsvc_remove_block(block); |
| 280 | return status; |
| 281 | } |
| 282 | |
| 283 | static void nlmsvc_free_block(struct kref *kref) |
| 284 | { |
| 285 | struct nlm_block *block = container_of(kref, struct nlm_block, b_count); |
| 286 | struct nlm_file *file = block->b_file; |
| 287 | |
| 288 | dprintk("lockd: freeing block %p...\n", block); |
| 289 | |
| 290 | /* Remove block from file's list of blocks */ |
| 291 | list_del_init(&block->b_flist); |
| 292 | mutex_unlock(&file->f_mutex); |
| 293 | |
| 294 | nlmsvc_freegrantargs(block->b_call); |
| 295 | nlmsvc_release_call(block->b_call); |
| 296 | nlm_release_file(block->b_file); |
| 297 | kfree(block); |
| 298 | } |
| 299 | |
| 300 | static void nlmsvc_release_block(struct nlm_block *block) |
| 301 | { |
| 302 | if (block != NULL) |
| 303 | kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex); |
| 304 | } |
| 305 | |
| 306 | /* |
| 307 | * Loop over all blocks and delete blocks held by |
| 308 | * a matching host. |
| 309 | */ |
| 310 | void nlmsvc_traverse_blocks(struct nlm_host *host, |
| 311 | struct nlm_file *file, |
| 312 | nlm_host_match_fn_t match) |
| 313 | { |
| 314 | struct nlm_block *block, *next; |
| 315 | |
| 316 | restart: |
| 317 | mutex_lock(&file->f_mutex); |
| 318 | list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) { |
| 319 | if (!match(block->b_host, host)) |
| 320 | continue; |
| 321 | /* Do not destroy blocks that are not on |
| 322 | * the global retry list - why? */ |
| 323 | if (list_empty(&block->b_list)) |
| 324 | continue; |
| 325 | kref_get(&block->b_count); |
| 326 | mutex_unlock(&file->f_mutex); |
| 327 | nlmsvc_unlink_block(block); |
| 328 | nlmsvc_release_block(block); |
| 329 | goto restart; |
| 330 | } |
| 331 | mutex_unlock(&file->f_mutex); |
| 332 | } |
| 333 | |
| 334 | /* |
| 335 | * Initialize arguments for GRANTED call. The nlm_rqst structure |
| 336 | * has been cleared already. |
| 337 | */ |
| 338 | static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock) |
| 339 | { |
| 340 | locks_copy_lock(&call->a_args.lock.fl, &lock->fl); |
| 341 | memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh)); |
| 342 | call->a_args.lock.caller = utsname()->nodename; |
| 343 | call->a_args.lock.oh.len = lock->oh.len; |
| 344 | |
| 345 | /* set default data area */ |
| 346 | call->a_args.lock.oh.data = call->a_owner; |
| 347 | call->a_args.lock.svid = lock->fl.fl_pid; |
| 348 | |
| 349 | if (lock->oh.len > NLMCLNT_OHSIZE) { |
| 350 | void *data = kmalloc(lock->oh.len, GFP_KERNEL); |
| 351 | if (!data) |
| 352 | return 0; |
| 353 | call->a_args.lock.oh.data = (u8 *) data; |
| 354 | } |
| 355 | |
| 356 | memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len); |
| 357 | return 1; |
| 358 | } |
| 359 | |
| 360 | static void nlmsvc_freegrantargs(struct nlm_rqst *call) |
| 361 | { |
| 362 | if (call->a_args.lock.oh.data != call->a_owner) |
| 363 | kfree(call->a_args.lock.oh.data); |
| 364 | |
| 365 | locks_release_private(&call->a_args.lock.fl); |
| 366 | } |
| 367 | |
| 368 | /* |
| 369 | * Deferred lock request handling for non-blocking lock |
| 370 | */ |
| 371 | static __be32 |
| 372 | nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block) |
| 373 | { |
| 374 | __be32 status = nlm_lck_denied_nolocks; |
| 375 | |
| 376 | block->b_flags |= B_QUEUED; |
| 377 | |
| 378 | nlmsvc_insert_block(block, NLM_TIMEOUT); |
| 379 | |
| 380 | block->b_cache_req = &rqstp->rq_chandle; |
| 381 | if (rqstp->rq_chandle.defer) { |
| 382 | block->b_deferred_req = |
| 383 | rqstp->rq_chandle.defer(block->b_cache_req); |
| 384 | if (block->b_deferred_req != NULL) |
| 385 | status = nlm_drop_reply; |
| 386 | } |
| 387 | dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n", |
| 388 | block, block->b_flags, ntohl(status)); |
| 389 | |
| 390 | return status; |
| 391 | } |
| 392 | |
| 393 | /* |
| 394 | * Attempt to establish a lock, and if it can't be granted, block it |
| 395 | * if required. |
| 396 | */ |
| 397 | __be32 |
| 398 | nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, |
| 399 | struct nlm_host *host, struct nlm_lock *lock, int wait, |
| 400 | struct nlm_cookie *cookie, int reclaim) |
| 401 | { |
| 402 | struct nlm_block *block = NULL; |
| 403 | int error; |
| 404 | __be32 ret; |
| 405 | |
| 406 | dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n", |
| 407 | file_inode(file->f_file)->i_sb->s_id, |
| 408 | file_inode(file->f_file)->i_ino, |
| 409 | lock->fl.fl_type, lock->fl.fl_pid, |
| 410 | (long long)lock->fl.fl_start, |
| 411 | (long long)lock->fl.fl_end, |
| 412 | wait); |
| 413 | |
| 414 | /* Lock file against concurrent access */ |
| 415 | mutex_lock(&file->f_mutex); |
| 416 | /* Get existing block (in case client is busy-waiting) |
| 417 | * or create new block |
| 418 | */ |
| 419 | block = nlmsvc_lookup_block(file, lock); |
| 420 | if (block == NULL) { |
| 421 | block = nlmsvc_create_block(rqstp, host, file, lock, cookie); |
| 422 | ret = nlm_lck_denied_nolocks; |
| 423 | if (block == NULL) |
| 424 | goto out; |
| 425 | lock = &block->b_call->a_args.lock; |
| 426 | } else |
| 427 | lock->fl.fl_flags &= ~FL_SLEEP; |
| 428 | |
| 429 | if (block->b_flags & B_QUEUED) { |
| 430 | dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n", |
| 431 | block, block->b_flags); |
| 432 | if (block->b_granted) { |
| 433 | nlmsvc_unlink_block(block); |
| 434 | ret = nlm_granted; |
| 435 | goto out; |
| 436 | } |
| 437 | if (block->b_flags & B_TIMED_OUT) { |
| 438 | nlmsvc_unlink_block(block); |
| 439 | ret = nlm_lck_denied; |
| 440 | goto out; |
| 441 | } |
| 442 | ret = nlm_drop_reply; |
| 443 | goto out; |
| 444 | } |
| 445 | |
| 446 | if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) { |
| 447 | ret = nlm_lck_denied_grace_period; |
| 448 | goto out; |
| 449 | } |
| 450 | if (reclaim && !locks_in_grace(SVC_NET(rqstp))) { |
| 451 | ret = nlm_lck_denied_grace_period; |
| 452 | goto out; |
| 453 | } |
| 454 | |
| 455 | if (!wait) |
| 456 | lock->fl.fl_flags &= ~FL_SLEEP; |
| 457 | error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL); |
| 458 | lock->fl.fl_flags &= ~FL_SLEEP; |
| 459 | |
| 460 | dprintk("lockd: vfs_lock_file returned %d\n", error); |
| 461 | switch (error) { |
| 462 | case 0: |
| 463 | ret = nlm_granted; |
| 464 | goto out; |
| 465 | case -EAGAIN: |
| 466 | /* |
| 467 | * If this is a blocking request for an |
| 468 | * already pending lock request then we need |
| 469 | * to put it back on lockd's block list |
| 470 | */ |
| 471 | if (wait) |
| 472 | break; |
| 473 | ret = nlm_lck_denied; |
| 474 | goto out; |
| 475 | case FILE_LOCK_DEFERRED: |
| 476 | if (wait) |
| 477 | break; |
| 478 | /* Filesystem lock operation is in progress |
| 479 | Add it to the queue waiting for callback */ |
| 480 | ret = nlmsvc_defer_lock_rqst(rqstp, block); |
| 481 | goto out; |
| 482 | case -EDEADLK: |
| 483 | ret = nlm_deadlock; |
| 484 | goto out; |
| 485 | default: /* includes ENOLCK */ |
| 486 | ret = nlm_lck_denied_nolocks; |
| 487 | goto out; |
| 488 | } |
| 489 | |
| 490 | ret = nlm_lck_blocked; |
| 491 | |
| 492 | /* Append to list of blocked */ |
| 493 | nlmsvc_insert_block(block, NLM_NEVER); |
| 494 | out: |
| 495 | mutex_unlock(&file->f_mutex); |
| 496 | nlmsvc_release_block(block); |
| 497 | dprintk("lockd: nlmsvc_lock returned %u\n", ret); |
| 498 | return ret; |
| 499 | } |
| 500 | |
| 501 | /* |
| 502 | * Test for presence of a conflicting lock. |
| 503 | */ |
| 504 | __be32 |
| 505 | nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file, |
| 506 | struct nlm_host *host, struct nlm_lock *lock, |
| 507 | struct nlm_lock *conflock, struct nlm_cookie *cookie) |
| 508 | { |
| 509 | int error; |
| 510 | __be32 ret; |
| 511 | |
| 512 | dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n", |
| 513 | file_inode(file->f_file)->i_sb->s_id, |
| 514 | file_inode(file->f_file)->i_ino, |
| 515 | lock->fl.fl_type, |
| 516 | (long long)lock->fl.fl_start, |
| 517 | (long long)lock->fl.fl_end); |
| 518 | |
| 519 | if (locks_in_grace(SVC_NET(rqstp))) { |
| 520 | ret = nlm_lck_denied_grace_period; |
| 521 | goto out; |
| 522 | } |
| 523 | |
| 524 | error = vfs_test_lock(file->f_file, &lock->fl); |
| 525 | if (error) { |
| 526 | /* We can't currently deal with deferred test requests */ |
| 527 | if (error == FILE_LOCK_DEFERRED) |
| 528 | WARN_ON_ONCE(1); |
| 529 | |
| 530 | ret = nlm_lck_denied_nolocks; |
| 531 | goto out; |
| 532 | } |
| 533 | |
| 534 | if (lock->fl.fl_type == F_UNLCK) { |
| 535 | ret = nlm_granted; |
| 536 | goto out; |
| 537 | } |
| 538 | |
| 539 | dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n", |
| 540 | lock->fl.fl_type, (long long)lock->fl.fl_start, |
| 541 | (long long)lock->fl.fl_end); |
| 542 | conflock->caller = "somehost"; /* FIXME */ |
| 543 | conflock->len = strlen(conflock->caller); |
| 544 | conflock->oh.len = 0; /* don't return OH info */ |
| 545 | conflock->svid = lock->fl.fl_pid; |
| 546 | conflock->fl.fl_type = lock->fl.fl_type; |
| 547 | conflock->fl.fl_start = lock->fl.fl_start; |
| 548 | conflock->fl.fl_end = lock->fl.fl_end; |
| 549 | locks_release_private(&lock->fl); |
| 550 | ret = nlm_lck_denied; |
| 551 | out: |
| 552 | return ret; |
| 553 | } |
| 554 | |
| 555 | /* |
| 556 | * Remove a lock. |
| 557 | * This implies a CANCEL call: We send a GRANT_MSG, the client replies |
| 558 | * with a GRANT_RES call which gets lost, and calls UNLOCK immediately |
| 559 | * afterwards. In this case the block will still be there, and hence |
| 560 | * must be removed. |
| 561 | */ |
| 562 | __be32 |
| 563 | nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock) |
| 564 | { |
| 565 | int error; |
| 566 | |
| 567 | dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n", |
| 568 | file_inode(file->f_file)->i_sb->s_id, |
| 569 | file_inode(file->f_file)->i_ino, |
| 570 | lock->fl.fl_pid, |
| 571 | (long long)lock->fl.fl_start, |
| 572 | (long long)lock->fl.fl_end); |
| 573 | |
| 574 | /* First, cancel any lock that might be there */ |
| 575 | nlmsvc_cancel_blocked(net, file, lock); |
| 576 | |
| 577 | lock->fl.fl_type = F_UNLCK; |
| 578 | error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL); |
| 579 | |
| 580 | return (error < 0)? nlm_lck_denied_nolocks : nlm_granted; |
| 581 | } |
| 582 | |
| 583 | /* |
| 584 | * Cancel a previously blocked request. |
| 585 | * |
| 586 | * A cancel request always overrides any grant that may currently |
| 587 | * be in progress. |
| 588 | * The calling procedure must check whether the file can be closed. |
| 589 | */ |
| 590 | __be32 |
| 591 | nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock) |
| 592 | { |
| 593 | struct nlm_block *block; |
| 594 | int status = 0; |
| 595 | |
| 596 | dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n", |
| 597 | file_inode(file->f_file)->i_sb->s_id, |
| 598 | file_inode(file->f_file)->i_ino, |
| 599 | lock->fl.fl_pid, |
| 600 | (long long)lock->fl.fl_start, |
| 601 | (long long)lock->fl.fl_end); |
| 602 | |
| 603 | if (locks_in_grace(net)) |
| 604 | return nlm_lck_denied_grace_period; |
| 605 | |
| 606 | mutex_lock(&file->f_mutex); |
| 607 | block = nlmsvc_lookup_block(file, lock); |
| 608 | mutex_unlock(&file->f_mutex); |
| 609 | if (block != NULL) { |
| 610 | vfs_cancel_lock(block->b_file->f_file, |
| 611 | &block->b_call->a_args.lock.fl); |
| 612 | status = nlmsvc_unlink_block(block); |
| 613 | nlmsvc_release_block(block); |
| 614 | } |
| 615 | return status ? nlm_lck_denied : nlm_granted; |
| 616 | } |
| 617 | |
| 618 | /* |
| 619 | * This is a callback from the filesystem for VFS file lock requests. |
| 620 | * It will be used if lm_grant is defined and the filesystem can not |
| 621 | * respond to the request immediately. |
| 622 | * For SETLK or SETLKW request it will get the local posix lock. |
| 623 | * In all cases it will move the block to the head of nlm_blocked q where |
| 624 | * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the |
| 625 | * deferred rpc for GETLK and SETLK. |
| 626 | */ |
| 627 | static void |
| 628 | nlmsvc_update_deferred_block(struct nlm_block *block, int result) |
| 629 | { |
| 630 | block->b_flags |= B_GOT_CALLBACK; |
| 631 | if (result == 0) |
| 632 | block->b_granted = 1; |
| 633 | else |
| 634 | block->b_flags |= B_TIMED_OUT; |
| 635 | } |
| 636 | |
| 637 | static int nlmsvc_grant_deferred(struct file_lock *fl, int result) |
| 638 | { |
| 639 | struct nlm_block *block; |
| 640 | int rc = -ENOENT; |
| 641 | |
| 642 | spin_lock(&nlm_blocked_lock); |
| 643 | list_for_each_entry(block, &nlm_blocked, b_list) { |
| 644 | if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) { |
| 645 | dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n", |
| 646 | block, block->b_flags); |
| 647 | if (block->b_flags & B_QUEUED) { |
| 648 | if (block->b_flags & B_TIMED_OUT) { |
| 649 | rc = -ENOLCK; |
| 650 | break; |
| 651 | } |
| 652 | nlmsvc_update_deferred_block(block, result); |
| 653 | } else if (result == 0) |
| 654 | block->b_granted = 1; |
| 655 | |
| 656 | nlmsvc_insert_block_locked(block, 0); |
| 657 | svc_wake_up(block->b_daemon); |
| 658 | rc = 0; |
| 659 | break; |
| 660 | } |
| 661 | } |
| 662 | spin_unlock(&nlm_blocked_lock); |
| 663 | if (rc == -ENOENT) |
| 664 | printk(KERN_WARNING "lockd: grant for unknown block\n"); |
| 665 | return rc; |
| 666 | } |
| 667 | |
| 668 | /* |
| 669 | * Unblock a blocked lock request. This is a callback invoked from the |
| 670 | * VFS layer when a lock on which we blocked is removed. |
| 671 | * |
| 672 | * This function doesn't grant the blocked lock instantly, but rather moves |
| 673 | * the block to the head of nlm_blocked where it can be picked up by lockd. |
| 674 | */ |
| 675 | static void |
| 676 | nlmsvc_notify_blocked(struct file_lock *fl) |
| 677 | { |
| 678 | struct nlm_block *block; |
| 679 | |
| 680 | dprintk("lockd: VFS unblock notification for block %p\n", fl); |
| 681 | spin_lock(&nlm_blocked_lock); |
| 682 | list_for_each_entry(block, &nlm_blocked, b_list) { |
| 683 | if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) { |
| 684 | nlmsvc_insert_block_locked(block, 0); |
| 685 | spin_unlock(&nlm_blocked_lock); |
| 686 | svc_wake_up(block->b_daemon); |
| 687 | return; |
| 688 | } |
| 689 | } |
| 690 | spin_unlock(&nlm_blocked_lock); |
| 691 | printk(KERN_WARNING "lockd: notification for unknown block!\n"); |
| 692 | } |
| 693 | |
| 694 | static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2) |
| 695 | { |
| 696 | return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid; |
| 697 | } |
| 698 | |
| 699 | /* |
| 700 | * Since NLM uses two "keys" for tracking locks, we need to hash them down |
| 701 | * to one for the blocked_hash. Here, we're just xor'ing the host address |
| 702 | * with the pid in order to create a key value for picking a hash bucket. |
| 703 | */ |
| 704 | static unsigned long |
| 705 | nlmsvc_owner_key(struct file_lock *fl) |
| 706 | { |
| 707 | return (unsigned long)fl->fl_owner ^ (unsigned long)fl->fl_pid; |
| 708 | } |
| 709 | |
| 710 | const struct lock_manager_operations nlmsvc_lock_operations = { |
| 711 | .lm_compare_owner = nlmsvc_same_owner, |
| 712 | .lm_owner_key = nlmsvc_owner_key, |
| 713 | .lm_notify = nlmsvc_notify_blocked, |
| 714 | .lm_grant = nlmsvc_grant_deferred, |
| 715 | }; |
| 716 | |
| 717 | /* |
| 718 | * Try to claim a lock that was previously blocked. |
| 719 | * |
| 720 | * Note that we use both the RPC_GRANTED_MSG call _and_ an async |
| 721 | * RPC thread when notifying the client. This seems like overkill... |
| 722 | * Here's why: |
| 723 | * - we don't want to use a synchronous RPC thread, otherwise |
| 724 | * we might find ourselves hanging on a dead portmapper. |
| 725 | * - Some lockd implementations (e.g. HP) don't react to |
| 726 | * RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls. |
| 727 | */ |
| 728 | static void |
| 729 | nlmsvc_grant_blocked(struct nlm_block *block) |
| 730 | { |
| 731 | struct nlm_file *file = block->b_file; |
| 732 | struct nlm_lock *lock = &block->b_call->a_args.lock; |
| 733 | int error; |
| 734 | loff_t fl_start, fl_end; |
| 735 | |
| 736 | dprintk("lockd: grant blocked lock %p\n", block); |
| 737 | |
| 738 | kref_get(&block->b_count); |
| 739 | |
| 740 | /* Unlink block request from list */ |
| 741 | nlmsvc_unlink_block(block); |
| 742 | |
| 743 | /* If b_granted is true this means we've been here before. |
| 744 | * Just retry the grant callback, possibly refreshing the RPC |
| 745 | * binding */ |
| 746 | if (block->b_granted) { |
| 747 | nlm_rebind_host(block->b_host); |
| 748 | goto callback; |
| 749 | } |
| 750 | |
| 751 | /* Try the lock operation again */ |
| 752 | /* vfs_lock_file() can mangle fl_start and fl_end, but we need |
| 753 | * them unchanged for the GRANT_MSG |
| 754 | */ |
| 755 | lock->fl.fl_flags |= FL_SLEEP; |
| 756 | fl_start = lock->fl.fl_start; |
| 757 | fl_end = lock->fl.fl_end; |
| 758 | error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL); |
| 759 | lock->fl.fl_flags &= ~FL_SLEEP; |
| 760 | lock->fl.fl_start = fl_start; |
| 761 | lock->fl.fl_end = fl_end; |
| 762 | |
| 763 | switch (error) { |
| 764 | case 0: |
| 765 | break; |
| 766 | case FILE_LOCK_DEFERRED: |
| 767 | dprintk("lockd: lock still blocked error %d\n", error); |
| 768 | nlmsvc_insert_block(block, NLM_NEVER); |
| 769 | nlmsvc_release_block(block); |
| 770 | return; |
| 771 | default: |
| 772 | printk(KERN_WARNING "lockd: unexpected error %d in %s!\n", |
| 773 | -error, __func__); |
| 774 | nlmsvc_insert_block(block, 10 * HZ); |
| 775 | nlmsvc_release_block(block); |
| 776 | return; |
| 777 | } |
| 778 | |
| 779 | callback: |
| 780 | /* Lock was granted by VFS. */ |
| 781 | dprintk("lockd: GRANTing blocked lock.\n"); |
| 782 | block->b_granted = 1; |
| 783 | |
| 784 | /* keep block on the list, but don't reattempt until the RPC |
| 785 | * completes or the submission fails |
| 786 | */ |
| 787 | nlmsvc_insert_block(block, NLM_NEVER); |
| 788 | |
| 789 | /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked |
| 790 | * will queue up a new one if this one times out |
| 791 | */ |
| 792 | error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG, |
| 793 | &nlmsvc_grant_ops); |
| 794 | |
| 795 | /* RPC submission failed, wait a bit and retry */ |
| 796 | if (error < 0) |
| 797 | nlmsvc_insert_block(block, 10 * HZ); |
| 798 | } |
| 799 | |
| 800 | /* |
| 801 | * This is the callback from the RPC layer when the NLM_GRANTED_MSG |
| 802 | * RPC call has succeeded or timed out. |
| 803 | * Like all RPC callbacks, it is invoked by the rpciod process, so it |
| 804 | * better not sleep. Therefore, we put the blocked lock on the nlm_blocked |
| 805 | * chain once more in order to have it removed by lockd itself (which can |
| 806 | * then sleep on the file semaphore without disrupting e.g. the nfs client). |
| 807 | */ |
| 808 | static void nlmsvc_grant_callback(struct rpc_task *task, void *data) |
| 809 | { |
| 810 | struct nlm_rqst *call = data; |
| 811 | struct nlm_block *block = call->a_block; |
| 812 | unsigned long timeout; |
| 813 | |
| 814 | dprintk("lockd: GRANT_MSG RPC callback\n"); |
| 815 | |
| 816 | spin_lock(&nlm_blocked_lock); |
| 817 | /* if the block is not on a list at this point then it has |
| 818 | * been invalidated. Don't try to requeue it. |
| 819 | * |
| 820 | * FIXME: it's possible that the block is removed from the list |
| 821 | * after this check but before the nlmsvc_insert_block. In that |
| 822 | * case it will be added back. Perhaps we need better locking |
| 823 | * for nlm_blocked? |
| 824 | */ |
| 825 | if (list_empty(&block->b_list)) |
| 826 | goto out; |
| 827 | |
| 828 | /* Technically, we should down the file semaphore here. Since we |
| 829 | * move the block towards the head of the queue only, no harm |
| 830 | * can be done, though. */ |
| 831 | if (task->tk_status < 0) { |
| 832 | /* RPC error: Re-insert for retransmission */ |
| 833 | timeout = 10 * HZ; |
| 834 | } else { |
| 835 | /* Call was successful, now wait for client callback */ |
| 836 | timeout = 60 * HZ; |
| 837 | } |
| 838 | nlmsvc_insert_block_locked(block, timeout); |
| 839 | svc_wake_up(block->b_daemon); |
| 840 | out: |
| 841 | spin_unlock(&nlm_blocked_lock); |
| 842 | } |
| 843 | |
| 844 | /* |
| 845 | * FIXME: nlmsvc_release_block() grabs a mutex. This is not allowed for an |
| 846 | * .rpc_release rpc_call_op |
| 847 | */ |
| 848 | static void nlmsvc_grant_release(void *data) |
| 849 | { |
| 850 | struct nlm_rqst *call = data; |
| 851 | nlmsvc_release_block(call->a_block); |
| 852 | } |
| 853 | |
| 854 | static const struct rpc_call_ops nlmsvc_grant_ops = { |
| 855 | .rpc_call_done = nlmsvc_grant_callback, |
| 856 | .rpc_release = nlmsvc_grant_release, |
| 857 | }; |
| 858 | |
| 859 | /* |
| 860 | * We received a GRANT_RES callback. Try to find the corresponding |
| 861 | * block. |
| 862 | */ |
| 863 | void |
| 864 | nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status) |
| 865 | { |
| 866 | struct nlm_block *block; |
| 867 | |
| 868 | dprintk("grant_reply: looking for cookie %x, s=%d \n", |
| 869 | *(unsigned int *)(cookie->data), status); |
| 870 | if (!(block = nlmsvc_find_block(cookie))) |
| 871 | return; |
| 872 | |
| 873 | if (block) { |
| 874 | if (status == nlm_lck_denied_grace_period) { |
| 875 | /* Try again in a couple of seconds */ |
| 876 | nlmsvc_insert_block(block, 10 * HZ); |
| 877 | } else { |
| 878 | /* Lock is now held by client, or has been rejected. |
| 879 | * In both cases, the block should be removed. */ |
| 880 | nlmsvc_unlink_block(block); |
| 881 | } |
| 882 | } |
| 883 | nlmsvc_release_block(block); |
| 884 | } |
| 885 | |
| 886 | /* Helper function to handle retry of a deferred block. |
| 887 | * If it is a blocking lock, call grant_blocked. |
| 888 | * For a non-blocking lock or test lock, revisit the request. |
| 889 | */ |
| 890 | static void |
| 891 | retry_deferred_block(struct nlm_block *block) |
| 892 | { |
| 893 | if (!(block->b_flags & B_GOT_CALLBACK)) |
| 894 | block->b_flags |= B_TIMED_OUT; |
| 895 | nlmsvc_insert_block(block, NLM_TIMEOUT); |
| 896 | dprintk("revisit block %p flags %d\n", block, block->b_flags); |
| 897 | if (block->b_deferred_req) { |
| 898 | block->b_deferred_req->revisit(block->b_deferred_req, 0); |
| 899 | block->b_deferred_req = NULL; |
| 900 | } |
| 901 | } |
| 902 | |
| 903 | /* |
| 904 | * Retry all blocked locks that have been notified. This is where lockd |
| 905 | * picks up locks that can be granted, or grant notifications that must |
| 906 | * be retransmitted. |
| 907 | */ |
| 908 | unsigned long |
| 909 | nlmsvc_retry_blocked(void) |
| 910 | { |
| 911 | unsigned long timeout = MAX_SCHEDULE_TIMEOUT; |
| 912 | struct nlm_block *block; |
| 913 | |
| 914 | spin_lock(&nlm_blocked_lock); |
| 915 | while (!list_empty(&nlm_blocked) && !kthread_should_stop()) { |
| 916 | block = list_entry(nlm_blocked.next, struct nlm_block, b_list); |
| 917 | |
| 918 | if (block->b_when == NLM_NEVER) |
| 919 | break; |
| 920 | if (time_after(block->b_when, jiffies)) { |
| 921 | timeout = block->b_when - jiffies; |
| 922 | break; |
| 923 | } |
| 924 | spin_unlock(&nlm_blocked_lock); |
| 925 | |
| 926 | dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n", |
| 927 | block, block->b_when); |
| 928 | if (block->b_flags & B_QUEUED) { |
| 929 | dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n", |
| 930 | block, block->b_granted, block->b_flags); |
| 931 | retry_deferred_block(block); |
| 932 | } else |
| 933 | nlmsvc_grant_blocked(block); |
| 934 | spin_lock(&nlm_blocked_lock); |
| 935 | } |
| 936 | spin_unlock(&nlm_blocked_lock); |
| 937 | |
| 938 | return timeout; |
| 939 | } |