svclock.c 23.3 KB
Newer Older
Linus Torvalds's avatar
Linus Torvalds committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
/*
 * linux/fs/lockd/svclock.c
 *
 * Handling of server-side locks, mostly of the blocked variety.
 * This is the ugliest part of lockd because we tread on very thin ice.
 * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
 * IMNSHO introducing the grant callback into the NLM protocol was one
 * of the worst ideas Sun ever had. Except maybe for the idea of doing
 * NFS file locking at all.
 *
 * I'm trying hard to avoid race conditions by protecting most accesses
 * to a file's list of blocked locks through a semaphore. The global
 * list of blocked locks is not protected in this fashion however.
 * Therefore, some functions (such as the RPC callback for the async grant
 * call) move blocked locks towards the head of the list *while some other
 * process might be traversing it*. This should not be a problem in
 * practice, because this will only cause functions traversing the list
 * to visit some blocks twice.
 *
 * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/smp_lock.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/svc.h>
#include <linux/lockd/nlm.h>
#include <linux/lockd/lockd.h>

#define NLMDBG_FACILITY		NLMDBG_SVCLOCK

#ifdef CONFIG_LOCKD_V4
#define nlm_deadlock	nlm4_deadlock
#else
#define nlm_deadlock	nlm_lck_denied
#endif

41
static void nlmsvc_release_block(struct nlm_block *block);
Linus Torvalds's avatar
Linus Torvalds committed
42
static void	nlmsvc_insert_block(struct nlm_block *block, unsigned long);
43
static void	nlmsvc_remove_block(struct nlm_block *block);
44

45 46
static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
static void nlmsvc_freegrantargs(struct nlm_rqst *call);
47
static const struct rpc_call_ops nlmsvc_grant_ops;
Linus Torvalds's avatar
Linus Torvalds committed
48 49 50 51

/*
 * The list of blocked locks to retry
 */
52
static LIST_HEAD(nlm_blocked);
Linus Torvalds's avatar
Linus Torvalds committed
53 54 55 56 57 58 59

/*
 * Insert a blocked lock into the global list
 */
static void
nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
{
60 61
	struct nlm_block *b;
	struct list_head *pos;
Linus Torvalds's avatar
Linus Torvalds committed
62 63

	dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
64 65 66 67 68 69 70
	if (list_empty(&block->b_list)) {
		kref_get(&block->b_count);
	} else {
		list_del_init(&block->b_list);
	}

	pos = &nlm_blocked;
Linus Torvalds's avatar
Linus Torvalds committed
71 72 73
	if (when != NLM_NEVER) {
		if ((when += jiffies) == NLM_NEVER)
			when ++;
74 75 76 77 78 79 80 81 82
		list_for_each(pos, &nlm_blocked) {
			b = list_entry(pos, struct nlm_block, b_list);
			if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
				break;
		}
		/* On normal exit from the loop, pos == &nlm_blocked,
		 * so we will be adding to the end of the list - good
		 */
	}
Linus Torvalds's avatar
Linus Torvalds committed
83

84
	list_add_tail(&block->b_list, pos);
Linus Torvalds's avatar
Linus Torvalds committed
85 86 87 88 89 90
	block->b_when = when;
}

/*
 * Remove a block from the global list
 */
91
static inline void
Linus Torvalds's avatar
Linus Torvalds committed
92 93
nlmsvc_remove_block(struct nlm_block *block)
{
94 95 96
	if (!list_empty(&block->b_list)) {
		list_del_init(&block->b_list);
		nlmsvc_release_block(block);
Linus Torvalds's avatar
Linus Torvalds committed
97 98 99 100
	}
}

/*
101
 * Find a block for a given lock
Linus Torvalds's avatar
Linus Torvalds committed
102 103
 */
static struct nlm_block *
104
nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
Linus Torvalds's avatar
Linus Torvalds committed
105
{
106
	struct nlm_block	*block;
Linus Torvalds's avatar
Linus Torvalds committed
107 108 109 110 111 112
	struct file_lock	*fl;

	dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
				file, lock->fl.fl_pid,
				(long long)lock->fl.fl_start,
				(long long)lock->fl.fl_end, lock->fl.fl_type);
113
	list_for_each_entry(block, &nlm_blocked, b_list) {
114
		fl = &block->b_call->a_args.lock.fl;
Linus Torvalds's avatar
Linus Torvalds committed
115 116 117 118
		dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
				block->b_file, fl->fl_pid,
				(long long)fl->fl_start,
				(long long)fl->fl_end, fl->fl_type,
119
				nlmdbg_cookie2a(&block->b_call->a_args.cookie));
Linus Torvalds's avatar
Linus Torvalds committed
120
		if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
121
			kref_get(&block->b_count);
Linus Torvalds's avatar
Linus Torvalds committed
122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141
			return block;
		}
	}

	return NULL;
}

static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
{
	if(a->len != b->len)
		return 0;
	if(memcmp(a->data,b->data,a->len))
		return 0;
	return 1;
}

/*
 * Find a block with a given NLM cookie.
 */
static inline struct nlm_block *
142
nlmsvc_find_block(struct nlm_cookie *cookie)
Linus Torvalds's avatar
Linus Torvalds committed
143 144 145
{
	struct nlm_block *block;

146
	list_for_each_entry(block, &nlm_blocked, b_list) {
147
		if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
148
			goto found;
Linus Torvalds's avatar
Linus Torvalds committed
149 150
	}

151 152 153
	return NULL;

found:
154
	dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
155
	kref_get(&block->b_count);
Linus Torvalds's avatar
Linus Torvalds committed
156 157 158 159 160 161 162 163 164 165 166 167
	return block;
}

/*
 * Create a block and initialize it.
 *
 * Note: we explicitly set the cookie of the grant reply to that of
 * the blocked lock request. The spec explicitly mentions that the client
 * should _not_ rely on the callback containing the same cookie as the
 * request, but (as I found out later) that's because some implementations
 * do just this. Never mind the standards comittees, they support our
 * logging industries.
168 169 170 171 172
 *
 * 10 years later: I hope we can safely ignore these old and broken
 * clients by now. Let's fix this so we can uniquely identify an incoming
 * GRANTED_RES message by cookie, without having to rely on the client's IP
 * address. --okir
Linus Torvalds's avatar
Linus Torvalds committed
173 174 175
 */
static inline struct nlm_block *
nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
Marc Eshel's avatar
Marc Eshel committed
176
		struct nlm_lock *lock, struct nlm_cookie *cookie)
Linus Torvalds's avatar
Linus Torvalds committed
177 178 179
{
	struct nlm_block	*block;
	struct nlm_host		*host;
180
	struct nlm_rqst		*call = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
181 182

	/* Create host handle for callback */
183
	host = nlmsvc_lookup_host(rqstp, lock->caller, lock->len);
Linus Torvalds's avatar
Linus Torvalds committed
184 185 186
	if (host == NULL)
		return NULL;

187 188 189 190
	call = nlm_alloc_call(host);
	if (call == NULL)
		return NULL;

Linus Torvalds's avatar
Linus Torvalds committed
191
	/* Allocate memory for block, and initialize arguments */
192 193
	block = kzalloc(sizeof(*block), GFP_KERNEL);
	if (block == NULL)
Linus Torvalds's avatar
Linus Torvalds committed
194
		goto failed;
195
	kref_init(&block->b_count);
196 197
	INIT_LIST_HEAD(&block->b_list);
	INIT_LIST_HEAD(&block->b_flist);
Linus Torvalds's avatar
Linus Torvalds committed
198

199
	if (!nlmsvc_setgrantargs(call, lock))
Linus Torvalds's avatar
Linus Torvalds committed
200 201 202
		goto failed_free;

	/* Set notifier function for VFS, and init args */
203 204
	call->a_args.lock.fl.fl_flags |= FL_SLEEP;
	call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
205
	nlmclnt_next_cookie(&call->a_args.cookie);
Linus Torvalds's avatar
Linus Torvalds committed
206 207 208 209 210 211 212

	dprintk("lockd: created block %p...\n", block);

	/* Create and initialize the block */
	block->b_daemon = rqstp->rq_server;
	block->b_host   = host;
	block->b_file   = file;
Marc Eshel's avatar
Marc Eshel committed
213
	block->b_fl = NULL;
214
	file->f_count++;
Linus Torvalds's avatar
Linus Torvalds committed
215 216

	/* Add to file's list of blocks */
217
	list_add(&block->b_flist, &file->f_blocks);
Linus Torvalds's avatar
Linus Torvalds committed
218 219

	/* Set up RPC arguments for callback */
220
	block->b_call = call;
Linus Torvalds's avatar
Linus Torvalds committed
221
	call->a_flags   = RPC_TASK_ASYNC;
222
	call->a_block = block;
Linus Torvalds's avatar
Linus Torvalds committed
223 224 225 226 227 228

	return block;

failed_free:
	kfree(block);
failed:
229
	nlm_release_call(call);
Linus Torvalds's avatar
Linus Torvalds committed
230 231 232 233 234 235 236 237 238
	return NULL;
}

/*
 * Delete a block. If the lock was cancelled or the grant callback
 * failed, unlock is set to 1.
 * It is the caller's responsibility to check whether the file
 * can be closed hereafter.
 */
239
static int nlmsvc_unlink_block(struct nlm_block *block)
Linus Torvalds's avatar
Linus Torvalds committed
240
{
241
	int status;
242
	dprintk("lockd: unlinking block %p...\n", block);
Linus Torvalds's avatar
Linus Torvalds committed
243 244

	/* Remove block from list */
245
	status = posix_unblock_lock(block->b_file->f_file, &block->b_call->a_args.lock.fl);
Linus Torvalds's avatar
Linus Torvalds committed
246
	nlmsvc_remove_block(block);
247 248
	return status;
}
Linus Torvalds's avatar
Linus Torvalds committed
249

250 251 252 253 254 255
static void nlmsvc_free_block(struct kref *kref)
{
	struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
	struct nlm_file		*file = block->b_file;

	dprintk("lockd: freeing block %p...\n", block);
Linus Torvalds's avatar
Linus Torvalds committed
256 257

	/* Remove block from file's list of blocks */
258
	mutex_lock(&file->f_mutex);
259
	list_del_init(&block->b_flist);
260
	mutex_unlock(&file->f_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
261

262 263
	nlmsvc_freegrantargs(block->b_call);
	nlm_release_call(block->b_call);
264
	nlm_release_file(block->b_file);
Marc Eshel's avatar
Marc Eshel committed
265
	kfree(block->b_fl);
Linus Torvalds's avatar
Linus Torvalds committed
266
	kfree(block);
267 268 269 270 271 272
}

static void nlmsvc_release_block(struct nlm_block *block)
{
	if (block != NULL)
		kref_put(&block->b_count, nlmsvc_free_block);
Linus Torvalds's avatar
Linus Torvalds committed
273 274
}

275 276 277 278 279 280 281
/*
 * Loop over all blocks and delete blocks held by
 * a matching host.
 */
void nlmsvc_traverse_blocks(struct nlm_host *host,
			struct nlm_file *file,
			nlm_host_match_fn_t match)
282
{
283
	struct nlm_block *block, *next;
284 285

restart:
286
	mutex_lock(&file->f_mutex);
287
	list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
288
		if (!match(block->b_host, host))
289
			continue;
290 291 292
		/* Do not destroy blocks that are not on
		 * the global retry list - why? */
		if (list_empty(&block->b_list))
293 294
			continue;
		kref_get(&block->b_count);
295
		mutex_unlock(&file->f_mutex);
296 297 298 299
		nlmsvc_unlink_block(block);
		nlmsvc_release_block(block);
		goto restart;
	}
300
	mutex_unlock(&file->f_mutex);
301 302
}

303 304 305 306 307 308 309 310
/*
 * Initialize arguments for GRANTED call. The nlm_rqst structure
 * has been cleared already.
 */
static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
{
	locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
	memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
311
	call->a_args.lock.caller = utsname()->nodename;
312 313 314 315 316 317 318 319
	call->a_args.lock.oh.len = lock->oh.len;

	/* set default data area */
	call->a_args.lock.oh.data = call->a_owner;
	call->a_args.lock.svid = lock->fl.fl_pid;

	if (lock->oh.len > NLMCLNT_OHSIZE) {
		void *data = kmalloc(lock->oh.len, GFP_KERNEL);
320
		if (!data)
321 322 323 324 325 326 327 328 329 330
			return 0;
		call->a_args.lock.oh.data = (u8 *) data;
	}

	memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
	return 1;
}

static void nlmsvc_freegrantargs(struct nlm_rqst *call)
{
331
	if (call->a_args.lock.oh.data != call->a_owner)
332 333 334
		kfree(call->a_args.lock.oh.data);
}

335 336 337
/*
 * Deferred lock request handling for non-blocking lock
 */
338
static __be32
339 340
nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
{
341
	__be32 status = nlm_lck_denied_nolocks;
342 343 344 345 346 347 348 349 350 351 352 353 354

	block->b_flags |= B_QUEUED;

	nlmsvc_insert_block(block, NLM_TIMEOUT);

	block->b_cache_req = &rqstp->rq_chandle;
	if (rqstp->rq_chandle.defer) {
		block->b_deferred_req =
			rqstp->rq_chandle.defer(block->b_cache_req);
		if (block->b_deferred_req != NULL)
			status = nlm_drop_reply;
	}
	dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
355
		block, block->b_flags, ntohl(status));
356 357 358 359

	return status;
}

Linus Torvalds's avatar
Linus Torvalds committed
360 361 362 363
/*
 * Attempt to establish a lock, and if it can't be granted, block it
 * if required.
 */
Al Viro's avatar
Al Viro committed
364
__be32
Linus Torvalds's avatar
Linus Torvalds committed
365 366 367
nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
			struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
{
368
	struct nlm_block	*block = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
369
	int			error;
Al Viro's avatar
Al Viro committed
370
	__be32			ret;
Linus Torvalds's avatar
Linus Torvalds committed
371 372

	dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
373 374
				file->f_file->f_path.dentry->d_inode->i_sb->s_id,
				file->f_file->f_path.dentry->d_inode->i_ino,
Linus Torvalds's avatar
Linus Torvalds committed
375 376 377 378 379 380 381
				lock->fl.fl_type, lock->fl.fl_pid,
				(long long)lock->fl.fl_start,
				(long long)lock->fl.fl_end,
				wait);


	/* Lock file against concurrent access */
382
	mutex_lock(&file->f_mutex);
383 384 385
	/* Get existing block (in case client is busy-waiting)
	 * or create new block
	 */
386
	block = nlmsvc_lookup_block(file, lock);
387
	if (block == NULL) {
388 389 390 391
		block = nlmsvc_create_block(rqstp, file, lock, cookie);
		ret = nlm_lck_denied_nolocks;
		if (block == NULL)
			goto out;
392
		lock = &block->b_call->a_args.lock;
393 394
	} else
		lock->fl.fl_flags &= ~FL_SLEEP;
Linus Torvalds's avatar
Linus Torvalds committed
395

396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411
	if (block->b_flags & B_QUEUED) {
		dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
							block, block->b_flags);
		if (block->b_granted) {
			nlmsvc_unlink_block(block);
			ret = nlm_granted;
			goto out;
		}
		if (block->b_flags & B_TIMED_OUT) {
			nlmsvc_unlink_block(block);
			ret = nlm_lck_denied;
			goto out;
		}
		ret = nlm_drop_reply;
		goto out;
	}
Linus Torvalds's avatar
Linus Torvalds committed
412

413 414 415 416
	if (!wait)
		lock->fl.fl_flags &= ~FL_SLEEP;
	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
	lock->fl.fl_flags &= ~FL_SLEEP;
417

418
	dprintk("lockd: vfs_lock_file returned %d\n", error);
419
	switch(error) {
Linus Torvalds's avatar
Linus Torvalds committed
420
		case 0:
Andy Adamson's avatar
Andy Adamson committed
421 422
			ret = nlm_granted;
			goto out;
423
		case -EAGAIN:
424
			ret = nlm_lck_denied;
425
			break;
426 427 428 429 430 431 432
		case -EINPROGRESS:
			if (wait)
				break;
			/* Filesystem lock operation is in progress
			   Add it to the queue waiting for callback */
			ret = nlmsvc_defer_lock_rqst(rqstp, block);
			goto out;
433
		case -EDEADLK:
Andy Adamson's avatar
Andy Adamson committed
434 435
			ret = nlm_deadlock;
			goto out;
Linus Torvalds's avatar
Linus Torvalds committed
436
		default:			/* includes ENOLCK */
Andy Adamson's avatar
Andy Adamson committed
437 438
			ret = nlm_lck_denied_nolocks;
			goto out;
Linus Torvalds's avatar
Linus Torvalds committed
439 440
	}

441 442 443 444 445
	ret = nlm_lck_denied;
	if (!wait)
		goto out;

	ret = nlm_lck_blocked;
Linus Torvalds's avatar
Linus Torvalds committed
446 447

	/* Append to list of blocked */
448
	nlmsvc_insert_block(block, NLM_NEVER);
Andy Adamson's avatar
Andy Adamson committed
449
out:
450
	mutex_unlock(&file->f_mutex);
451
	nlmsvc_release_block(block);
Andy Adamson's avatar
Andy Adamson committed
452 453
	dprintk("lockd: nlmsvc_lock returned %u\n", ret);
	return ret;
Linus Torvalds's avatar
Linus Torvalds committed
454 455 456 457 458
}

/*
 * Test for presence of a conflicting lock.
 */
Al Viro's avatar
Al Viro committed
459
__be32
460 461 462
nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
		struct nlm_lock *lock, struct nlm_lock *conflock,
		struct nlm_cookie *cookie)
Linus Torvalds's avatar
Linus Torvalds committed
463
{
Marc Eshel's avatar
Marc Eshel committed
464 465 466 467
	struct nlm_block 	*block = NULL;
	int			error;
	__be32			ret;

Linus Torvalds's avatar
Linus Torvalds committed
468
	dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
469 470
				file->f_file->f_path.dentry->d_inode->i_sb->s_id,
				file->f_file->f_path.dentry->d_inode->i_ino,
Linus Torvalds's avatar
Linus Torvalds committed
471 472 473 474
				lock->fl.fl_type,
				(long long)lock->fl.fl_start,
				(long long)lock->fl.fl_end);

Marc Eshel's avatar
Marc Eshel committed
475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508
	/* Get existing block (in case client is busy-waiting) */
	block = nlmsvc_lookup_block(file, lock);

	if (block == NULL) {
		struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL);

		if (conf == NULL)
			return nlm_granted;
		block = nlmsvc_create_block(rqstp, file, lock, cookie);
		if (block == NULL) {
			kfree(conf);
			return nlm_granted;
		}
		block->b_fl = conf;
	}
	if (block->b_flags & B_QUEUED) {
		dprintk("lockd: nlmsvc_testlock deferred block %p flags %d fl %p\n",
			block, block->b_flags, block->b_fl);
		if (block->b_flags & B_TIMED_OUT) {
			nlmsvc_unlink_block(block);
			return nlm_lck_denied;
		}
		if (block->b_flags & B_GOT_CALLBACK) {
			if (block->b_fl != NULL
					&& block->b_fl->fl_type != F_UNLCK) {
				lock->fl = *block->b_fl;
				goto conf_lock;
			}
			else {
				nlmsvc_unlink_block(block);
				return nlm_granted;
			}
		}
		return nlm_drop_reply;
Linus Torvalds's avatar
Linus Torvalds committed
509 510
	}

Marc Eshel's avatar
Marc Eshel committed
511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538
	error = vfs_test_lock(file->f_file, &lock->fl);
	if (error == -EINPROGRESS)
		return nlmsvc_defer_lock_rqst(rqstp, block);
	if (error) {
		ret = nlm_lck_denied_nolocks;
		goto out;
	}
	if (lock->fl.fl_type == F_UNLCK) {
		ret = nlm_granted;
		goto out;
	}

conf_lock:
	dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
		lock->fl.fl_type, (long long)lock->fl.fl_start,
		(long long)lock->fl.fl_end);
	conflock->caller = "somehost";	/* FIXME */
	conflock->len = strlen(conflock->caller);
	conflock->oh.len = 0;		/* don't return OH info */
	conflock->svid = lock->fl.fl_pid;
	conflock->fl.fl_type = lock->fl.fl_type;
	conflock->fl.fl_start = lock->fl.fl_start;
	conflock->fl.fl_end = lock->fl.fl_end;
	ret = nlm_lck_denied;
out:
	if (block)
		nlmsvc_release_block(block);
	return ret;
Linus Torvalds's avatar
Linus Torvalds committed
539 540 541 542 543 544 545 546 547
}

/*
 * Remove a lock.
 * This implies a CANCEL call: We send a GRANT_MSG, the client replies
 * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
 * afterwards. In this case the block will still be there, and hence
 * must be removed.
 */
Al Viro's avatar
Al Viro committed
548
__be32
Linus Torvalds's avatar
Linus Torvalds committed
549 550 551 552 553
nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
{
	int	error;

	dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
554 555
				file->f_file->f_path.dentry->d_inode->i_sb->s_id,
				file->f_file->f_path.dentry->d_inode->i_ino,
Linus Torvalds's avatar
Linus Torvalds committed
556 557 558 559 560 561 562 563
				lock->fl.fl_pid,
				(long long)lock->fl.fl_start,
				(long long)lock->fl.fl_end);

	/* First, cancel any lock that might be there */
	nlmsvc_cancel_blocked(file, lock);

	lock->fl.fl_type = F_UNLCK;
564
	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
565 566 567 568 569 570 571 572 573 574 575

	return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
}

/*
 * Cancel a previously blocked request.
 *
 * A cancel request always overrides any grant that may currently
 * be in progress.
 * The calling procedure must check whether the file can be closed.
 */
Al Viro's avatar
Al Viro committed
576
__be32
Linus Torvalds's avatar
Linus Torvalds committed
577 578 579
nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
{
	struct nlm_block	*block;
J. Bruce Fields's avatar
J. Bruce Fields committed
580
	int status = 0;
Linus Torvalds's avatar
Linus Torvalds committed
581 582

	dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
583 584
				file->f_file->f_path.dentry->d_inode->i_sb->s_id,
				file->f_file->f_path.dentry->d_inode->i_ino,
Linus Torvalds's avatar
Linus Torvalds committed
585 586 587 588
				lock->fl.fl_pid,
				(long long)lock->fl.fl_start,
				(long long)lock->fl.fl_end);

589
	mutex_lock(&file->f_mutex);
590
	block = nlmsvc_lookup_block(file, lock);
591
	mutex_unlock(&file->f_mutex);
592
	if (block != NULL) {
593 594
		vfs_cancel_lock(block->b_file->f_file,
				&block->b_call->a_args.lock.fl);
595 596 597
		status = nlmsvc_unlink_block(block);
		nlmsvc_release_block(block);
	}
J. Bruce Fields's avatar
J. Bruce Fields committed
598
	return status ? nlm_lck_denied : nlm_granted;
Linus Torvalds's avatar
Linus Torvalds committed
599 600
}

Marc Eshel's avatar
Marc Eshel committed
601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657
/*
 * This is a callback from the filesystem for VFS file lock requests.
 * It will be used if fl_grant is defined and the filesystem can not
 * respond to the request immediately.
 * For GETLK request it will copy the reply to the nlm_block.
 * For SETLK or SETLKW request it will get the local posix lock.
 * In all cases it will move the block to the head of nlm_blocked q where
 * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
 * deferred rpc for GETLK and SETLK.
 */
static void
nlmsvc_update_deferred_block(struct nlm_block *block, struct file_lock *conf,
			     int result)
{
	block->b_flags |= B_GOT_CALLBACK;
	if (result == 0)
		block->b_granted = 1;
	else
		block->b_flags |= B_TIMED_OUT;
	if (conf) {
		if (block->b_fl)
			locks_copy_lock(block->b_fl, conf);
	}
}

static int nlmsvc_grant_deferred(struct file_lock *fl, struct file_lock *conf,
					int result)
{
	struct nlm_block *block;
	int rc = -ENOENT;

	lock_kernel();
	list_for_each_entry(block, &nlm_blocked, b_list) {
		if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
			dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
							block, block->b_flags);
			if (block->b_flags & B_QUEUED) {
				if (block->b_flags & B_TIMED_OUT) {
					rc = -ENOLCK;
					break;
				}
				nlmsvc_update_deferred_block(block, conf, result);
			} else if (result == 0)
				block->b_granted = 1;

			nlmsvc_insert_block(block, 0);
			svc_wake_up(block->b_daemon);
			rc = 0;
			break;
		}
	}
	unlock_kernel();
	if (rc == -ENOENT)
		printk(KERN_WARNING "lockd: grant for unknown block\n");
	return rc;
}

Linus Torvalds's avatar
Linus Torvalds committed
658 659 660 661 662 663 664 665 666 667
/*
 * Unblock a blocked lock request. This is a callback invoked from the
 * VFS layer when a lock on which we blocked is removed.
 *
 * This function doesn't grant the blocked lock instantly, but rather moves
 * the block to the head of nlm_blocked where it can be picked up by lockd.
 */
static void
nlmsvc_notify_blocked(struct file_lock *fl)
{
668
	struct nlm_block	*block;
Linus Torvalds's avatar
Linus Torvalds committed
669 670

	dprintk("lockd: VFS unblock notification for block %p\n", fl);
671
	list_for_each_entry(block, &nlm_blocked, b_list) {
672
		if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
Linus Torvalds's avatar
Linus Torvalds committed
673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689
			nlmsvc_insert_block(block, 0);
			svc_wake_up(block->b_daemon);
			return;
		}
	}

	printk(KERN_WARNING "lockd: notification for unknown block!\n");
}

static int nlmsvc_same_owner(struct file_lock *fl1, struct file_lock *fl2)
{
	return fl1->fl_owner == fl2->fl_owner && fl1->fl_pid == fl2->fl_pid;
}

struct lock_manager_operations nlmsvc_lock_operations = {
	.fl_compare_owner = nlmsvc_same_owner,
	.fl_notify = nlmsvc_notify_blocked,
Marc Eshel's avatar
Marc Eshel committed
690
	.fl_grant = nlmsvc_grant_deferred,
Linus Torvalds's avatar
Linus Torvalds committed
691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707
};

/*
 * Try to claim a lock that was previously blocked.
 *
 * Note that we use both the RPC_GRANTED_MSG call _and_ an async
 * RPC thread when notifying the client. This seems like overkill...
 * Here's why:
 *  -	we don't want to use a synchronous RPC thread, otherwise
 *	we might find ourselves hanging on a dead portmapper.
 *  -	Some lockd implementations (e.g. HP) don't react to
 *	RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
 */
static void
nlmsvc_grant_blocked(struct nlm_block *block)
{
	struct nlm_file		*file = block->b_file;
708
	struct nlm_lock		*lock = &block->b_call->a_args.lock;
Linus Torvalds's avatar
Linus Torvalds committed
709 710 711 712
	int			error;

	dprintk("lockd: grant blocked lock %p\n", block);

Marc Eshel's avatar
Marc Eshel committed
713 714
	kref_get(&block->b_count);

Linus Torvalds's avatar
Linus Torvalds committed
715
	/* Unlink block request from list */
716
	nlmsvc_unlink_block(block);
Linus Torvalds's avatar
Linus Torvalds committed
717 718 719 720 721 722 723 724 725 726

	/* If b_granted is true this means we've been here before.
	 * Just retry the grant callback, possibly refreshing the RPC
	 * binding */
	if (block->b_granted) {
		nlm_rebind_host(block->b_host);
		goto callback;
	}

	/* Try the lock operation again */
727
	lock->fl.fl_flags |= FL_SLEEP;
728
	error = vfs_lock_file(file->f_file, F_SETLK, &lock->fl, NULL);
729 730
	lock->fl.fl_flags &= ~FL_SLEEP;

731 732 733 734
	switch (error) {
	case 0:
		break;
	case -EAGAIN:
735 736
	case -EINPROGRESS:
		dprintk("lockd: lock still blocked error %d\n", error);
Linus Torvalds's avatar
Linus Torvalds committed
737
		nlmsvc_insert_block(block, NLM_NEVER);
Marc Eshel's avatar
Marc Eshel committed
738
		nlmsvc_release_block(block);
739
		return;
740
	default:
Linus Torvalds's avatar
Linus Torvalds committed
741 742 743
		printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
				-error, __FUNCTION__);
		nlmsvc_insert_block(block, 10 * HZ);
Marc Eshel's avatar
Marc Eshel committed
744
		nlmsvc_release_block(block);
745
		return;
Linus Torvalds's avatar
Linus Torvalds committed
746 747 748 749 750 751 752 753 754 755 756
	}

callback:
	/* Lock was granted by VFS. */
	dprintk("lockd: GRANTing blocked lock.\n");
	block->b_granted = 1;

	/* Schedule next grant callback in 30 seconds */
	nlmsvc_insert_block(block, 30 * HZ);

	/* Call the client */
757
	nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG, &nlmsvc_grant_ops);
Linus Torvalds's avatar
Linus Torvalds committed
758 759 760 761 762 763 764 765 766 767
}

/*
 * This is the callback from the RPC layer when the NLM_GRANTED_MSG
 * RPC call has succeeded or timed out.
 * Like all RPC callbacks, it is invoked by the rpciod process, so it
 * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
 * chain once more in order to have it removed by lockd itself (which can
 * then sleep on the file semaphore without disrupting e.g. the nfs client).
 */
768
static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
Linus Torvalds's avatar
Linus Torvalds committed
769
{
770
	struct nlm_rqst		*call = data;
771
	struct nlm_block	*block = call->a_block;
Linus Torvalds's avatar
Linus Torvalds committed
772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787
	unsigned long		timeout;

	dprintk("lockd: GRANT_MSG RPC callback\n");

	/* Technically, we should down the file semaphore here. Since we
	 * move the block towards the head of the queue only, no harm
	 * can be done, though. */
	if (task->tk_status < 0) {
		/* RPC error: Re-insert for retransmission */
		timeout = 10 * HZ;
	} else {
		/* Call was successful, now wait for client callback */
		timeout = 60 * HZ;
	}
	nlmsvc_insert_block(block, timeout);
	svc_wake_up(block->b_daemon);
788 789
}

Adrian Bunk's avatar
Adrian Bunk committed
790
static void nlmsvc_grant_release(void *data)
791
{
792 793 794
	struct nlm_rqst		*call = data;

	nlmsvc_release_block(call->a_block);
Linus Torvalds's avatar
Linus Torvalds committed
795 796
}

797 798
static const struct rpc_call_ops nlmsvc_grant_ops = {
	.rpc_call_done = nlmsvc_grant_callback,
799
	.rpc_release = nlmsvc_grant_release,
800 801
};

Linus Torvalds's avatar
Linus Torvalds committed
802 803 804 805 806
/*
 * We received a GRANT_RES callback. Try to find the corresponding
 * block.
 */
void
Al Viro's avatar
Al Viro committed
807
nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
Linus Torvalds's avatar
Linus Torvalds committed
808 809 810
{
	struct nlm_block	*block;

811 812 813
	dprintk("grant_reply: looking for cookie %x, s=%d \n",
		*(unsigned int *)(cookie->data), status);
	if (!(block = nlmsvc_find_block(cookie)))
Linus Torvalds's avatar
Linus Torvalds committed
814 815
		return;

816
	if (block) {
Al Viro's avatar
Al Viro committed
817
		if (status == nlm_lck_denied_grace_period) {
Linus Torvalds's avatar
Linus Torvalds committed
818 819 820 821 822
			/* Try again in a couple of seconds */
			nlmsvc_insert_block(block, 10 * HZ);
		} else {
			/* Lock is now held by client, or has been rejected.
			 * In both cases, the block should be removed. */
823
			nlmsvc_unlink_block(block);
Linus Torvalds's avatar
Linus Torvalds committed
824 825
		}
	}
826
	nlmsvc_release_block(block);
Linus Torvalds's avatar
Linus Torvalds committed
827 828
}

Marc Eshel's avatar
Marc Eshel committed
829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845
/* Helper function to handle retry of a deferred block.
 * If it is a blocking lock, call grant_blocked.
 * For a non-blocking lock or test lock, revisit the request.
 */
static void
retry_deferred_block(struct nlm_block *block)
{
	if (!(block->b_flags & B_GOT_CALLBACK))
		block->b_flags |= B_TIMED_OUT;
	nlmsvc_insert_block(block, NLM_TIMEOUT);
	dprintk("revisit block %p flags %d\n",	block, block->b_flags);
	if (block->b_deferred_req) {
		block->b_deferred_req->revisit(block->b_deferred_req, 0);
		block->b_deferred_req = NULL;
	}
}

Linus Torvalds's avatar
Linus Torvalds committed
846 847 848 849 850 851 852 853
/*
 * Retry all blocked locks that have been notified. This is where lockd
 * picks up locks that can be granted, or grant notifications that must
 * be retransmitted.
 */
unsigned long
nlmsvc_retry_blocked(void)
{
854 855 856 857 858
	unsigned long	timeout = MAX_SCHEDULE_TIMEOUT;
	struct nlm_block *block;

	while (!list_empty(&nlm_blocked)) {
		block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
Linus Torvalds's avatar
Linus Torvalds committed
859 860 861

		if (block->b_when == NLM_NEVER)
			break;
862 863
	        if (time_after(block->b_when,jiffies)) {
			timeout = block->b_when - jiffies;
Linus Torvalds's avatar
Linus Torvalds committed
864
			break;
865 866
		}

J. Bruce Fields's avatar
J. Bruce Fields committed
867 868
		dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
			block, block->b_when);
Marc Eshel's avatar
Marc Eshel committed
869 870 871 872 873 874
		if (block->b_flags & B_QUEUED) {
			dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
				block, block->b_granted, block->b_flags);
			retry_deferred_block(block);
		} else
			nlmsvc_grant_blocked(block);
Linus Torvalds's avatar
Linus Torvalds committed
875 876
	}

877
	return timeout;
Linus Torvalds's avatar
Linus Torvalds committed
878
}