svclock.c 21.8 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
173 174 175 176 177 178 179
 */
static inline struct nlm_block *
nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file,
				struct nlm_lock *lock, struct nlm_cookie *cookie)
{
	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;
213
	file->f_count++;
Linus Torvalds's avatar
Linus Torvalds committed
214 215

	/* Add to file's list of blocks */
216
	list_add(&block->b_flist, &file->f_blocks);
Linus Torvalds's avatar
Linus Torvalds committed
217 218

	/* Set up RPC arguments for callback */
219
	block->b_call = call;
Linus Torvalds's avatar
Linus Torvalds committed
220
	call->a_flags   = RPC_TASK_ASYNC;
221
	call->a_block = block;
Linus Torvalds's avatar
Linus Torvalds committed
222 223 224 225 226 227

	return block;

failed_free:
	kfree(block);
failed:
228
	nlm_release_call(call);
Linus Torvalds's avatar
Linus Torvalds committed
229 230 231 232 233 234 235 236 237
	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.
 */
238
static int nlmsvc_unlink_block(struct nlm_block *block)
Linus Torvalds's avatar
Linus Torvalds committed
239
{
240
	int status;
241
	dprintk("lockd: unlinking block %p...\n", block);
Linus Torvalds's avatar
Linus Torvalds committed
242 243

	/* Remove block from list */
244
	status = posix_unblock_lock(block->b_file->f_file, &block->b_call->a_args.lock.fl);
Linus Torvalds's avatar
Linus Torvalds committed
245
	nlmsvc_remove_block(block);
246 247
	return status;
}
Linus Torvalds's avatar
Linus Torvalds committed
248

249 250 251 252 253 254
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
255 256

	/* Remove block from file's list of blocks */
257
	mutex_lock(&file->f_mutex);
258
	list_del_init(&block->b_flist);
259
	mutex_unlock(&file->f_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
260

261 262
	nlmsvc_freegrantargs(block->b_call);
	nlm_release_call(block->b_call);
263
	nlm_release_file(block->b_file);
Marc Eshel's avatar
Marc Eshel committed
264
	kfree(block->b_fl);
Linus Torvalds's avatar
Linus Torvalds committed
265
	kfree(block);
266 267 268 269 270 271
}

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
272 273
}

274 275 276 277 278 279 280
/*
 * 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)
281
{
282
	struct nlm_block *block, *next;
283 284

restart:
285
	mutex_lock(&file->f_mutex);
286
	list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
287
		if (!match(block->b_host, host))
288
			continue;
289 290 291
		/* Do not destroy blocks that are not on
		 * the global retry list - why? */
		if (list_empty(&block->b_list))
292 293
			continue;
		kref_get(&block->b_count);
294
		mutex_unlock(&file->f_mutex);
295 296 297 298
		nlmsvc_unlink_block(block);
		nlmsvc_release_block(block);
		goto restart;
	}
299
	mutex_unlock(&file->f_mutex);
300 301
}

302 303 304 305 306 307 308 309
/*
 * 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));
310
	call->a_args.lock.caller = utsname()->nodename;
311 312 313 314 315 316 317 318
	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);
319
		if (!data)
320 321 322 323 324 325 326 327 328 329
			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)
{
330
	if (call->a_args.lock.oh.data != call->a_owner)
331 332 333
		kfree(call->a_args.lock.oh.data);
}

334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358
/*
 * Deferred lock request handling for non-blocking lock
 */
static u32
nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
{
	u32 status = nlm_lck_denied_nolocks;

	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",
		block, block->b_flags, status);

	return status;
}

Linus Torvalds's avatar
Linus Torvalds committed
359 360 361 362
/*
 * Attempt to establish a lock, and if it can't be granted, block it
 * if required.
 */
Al Viro's avatar
Al Viro committed
363
__be32
Linus Torvalds's avatar
Linus Torvalds committed
364 365 366
nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
			struct nlm_lock *lock, int wait, struct nlm_cookie *cookie)
{
367
	struct nlm_block	*block, *newblock = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
368
	int			error;
Al Viro's avatar
Al Viro committed
369
	__be32			ret;
Linus Torvalds's avatar
Linus Torvalds committed
370 371

	dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
372 373
				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
374 375 376 377 378 379
				lock->fl.fl_type, lock->fl.fl_pid,
				(long long)lock->fl.fl_start,
				(long long)lock->fl.fl_end,
				wait);


380
	lock->fl.fl_flags &= ~FL_SLEEP;
Linus Torvalds's avatar
Linus Torvalds committed
381 382
again:
	/* Lock file against concurrent access */
383
	mutex_lock(&file->f_mutex);
384
	/* Get existing block (in case client is busy-waiting) */
385
	block = nlmsvc_lookup_block(file, lock);
386 387
	if (block == NULL) {
		if (newblock != NULL)
388
			lock = &newblock->b_call->a_args.lock;
389
	} else
390
		lock = &block->b_call->a_args.lock;
Linus Torvalds's avatar
Linus Torvalds committed
391

392
	error = posix_lock_file(file->f_file, &lock->fl, NULL);
393
	lock->fl.fl_flags &= ~FL_SLEEP;
Linus Torvalds's avatar
Linus Torvalds committed
394

395 396
	dprintk("lockd: posix_lock_file returned %d\n", error);

397
	switch(error) {
Linus Torvalds's avatar
Linus Torvalds committed
398
		case 0:
Andy Adamson's avatar
Andy Adamson committed
399 400
			ret = nlm_granted;
			goto out;
401 402 403
		case -EAGAIN:
			break;
		case -EDEADLK:
Andy Adamson's avatar
Andy Adamson committed
404 405
			ret = nlm_deadlock;
			goto out;
Linus Torvalds's avatar
Linus Torvalds committed
406
		default:			/* includes ENOLCK */
Andy Adamson's avatar
Andy Adamson committed
407 408
			ret = nlm_lck_denied_nolocks;
			goto out;
Linus Torvalds's avatar
Linus Torvalds committed
409 410
	}

411 412 413 414 415 416 417
	ret = nlm_lck_denied;
	if (!wait)
		goto out;

	ret = nlm_lck_blocked;
	if (block != NULL)
		goto out;
Linus Torvalds's avatar
Linus Torvalds committed
418 419 420

	/* If we don't have a block, create and initialize it. Then
	 * retry because we may have slept in kmalloc. */
421
	/* We have to release f_mutex as nlmsvc_create_block may try to
Linus Torvalds's avatar
Linus Torvalds committed
422
	 * to claim it while doing host garbage collection */
423
	if (newblock == NULL) {
424
		mutex_unlock(&file->f_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
425
		dprintk("lockd: blocking on this lock (allocating).\n");
426
		if (!(newblock = nlmsvc_create_block(rqstp, file, lock, cookie)))
Linus Torvalds's avatar
Linus Torvalds committed
427 428 429 430 431
			return nlm_lck_denied_nolocks;
		goto again;
	}

	/* Append to list of blocked */
432
	nlmsvc_insert_block(newblock, NLM_NEVER);
Andy Adamson's avatar
Andy Adamson committed
433
out:
434
	mutex_unlock(&file->f_mutex);
435 436
	nlmsvc_release_block(newblock);
	nlmsvc_release_block(block);
Andy Adamson's avatar
Andy Adamson committed
437 438
	dprintk("lockd: nlmsvc_lock returned %u\n", ret);
	return ret;
Linus Torvalds's avatar
Linus Torvalds committed
439 440 441 442 443
}

/*
 * Test for presence of a conflicting lock.
 */
Al Viro's avatar
Al Viro committed
444
__be32
Linus Torvalds's avatar
Linus Torvalds committed
445 446 447 448
nlmsvc_testlock(struct nlm_file *file, struct nlm_lock *lock,
				       struct nlm_lock *conflock)
{
	dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
449 450
				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
451 452 453 454
				lock->fl.fl_type,
				(long long)lock->fl.fl_start,
				(long long)lock->fl.fl_end);

455
	if (posix_test_lock(file->f_file, &lock->fl)) {
Linus Torvalds's avatar
Linus Torvalds committed
456
		dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
457 458 459
				lock->fl.fl_type,
				(long long)lock->fl.fl_start,
				(long long)lock->fl.fl_end);
Linus Torvalds's avatar
Linus Torvalds committed
460
		conflock->caller = "somehost";	/* FIXME */
461
		conflock->len = strlen(conflock->caller);
Linus Torvalds's avatar
Linus Torvalds committed
462
		conflock->oh.len = 0;		/* don't return OH info */
463 464 465 466
		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;
Linus Torvalds's avatar
Linus Torvalds committed
467 468 469 470 471 472 473 474 475 476 477 478 479
		return nlm_lck_denied;
	}

	return nlm_granted;
}

/*
 * 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
480
__be32
Linus Torvalds's avatar
Linus Torvalds committed
481 482 483 484 485
nlmsvc_unlock(struct nlm_file *file, struct nlm_lock *lock)
{
	int	error;

	dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
486 487
				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
488 489 490 491 492 493 494 495
				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;
496
	error = posix_lock_file(file->f_file, &lock->fl, NULL);
Linus Torvalds's avatar
Linus Torvalds committed
497 498 499 500 501 502 503 504 505 506 507

	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
508
__be32
Linus Torvalds's avatar
Linus Torvalds committed
509 510 511
nlmsvc_cancel_blocked(struct nlm_file *file, struct nlm_lock *lock)
{
	struct nlm_block	*block;
J. Bruce Fields's avatar
J. Bruce Fields committed
512
	int status = 0;
Linus Torvalds's avatar
Linus Torvalds committed
513 514

	dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
515 516
				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
517 518 519 520
				lock->fl.fl_pid,
				(long long)lock->fl.fl_start,
				(long long)lock->fl.fl_end);

521
	mutex_lock(&file->f_mutex);
522
	block = nlmsvc_lookup_block(file, lock);
523
	mutex_unlock(&file->f_mutex);
524
	if (block != NULL) {
525 526 527
		status = nlmsvc_unlink_block(block);
		nlmsvc_release_block(block);
	}
J. Bruce Fields's avatar
J. Bruce Fields committed
528
	return status ? nlm_lck_denied : nlm_granted;
Linus Torvalds's avatar
Linus Torvalds committed
529 530
}

Marc Eshel's avatar
Marc Eshel committed
531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588
/*
 * 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) {
		block->b_fl = kzalloc(sizeof(struct file_lock), GFP_KERNEL);
		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
589 590 591 592 593 594 595 596 597 598
/*
 * 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)
{
599
	struct nlm_block	*block;
Linus Torvalds's avatar
Linus Torvalds committed
600 601

	dprintk("lockd: VFS unblock notification for block %p\n", fl);
602
	list_for_each_entry(block, &nlm_blocked, b_list) {
603
		if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
Linus Torvalds's avatar
Linus Torvalds committed
604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620
			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
621
	.fl_grant = nlmsvc_grant_deferred,
Linus Torvalds's avatar
Linus Torvalds committed
622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638
};

/*
 * 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;
639
	struct nlm_lock		*lock = &block->b_call->a_args.lock;
Linus Torvalds's avatar
Linus Torvalds committed
640 641 642 643
	int			error;

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

Marc Eshel's avatar
Marc Eshel committed
644 645
	kref_get(&block->b_count);

Linus Torvalds's avatar
Linus Torvalds committed
646
	/* Unlink block request from list */
647
	nlmsvc_unlink_block(block);
Linus Torvalds's avatar
Linus Torvalds committed
648 649 650 651 652 653 654 655 656 657

	/* 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 */
658
	lock->fl.fl_flags |= FL_SLEEP;
659
	error = posix_lock_file(file->f_file, &lock->fl, NULL);
660 661
	lock->fl.fl_flags &= ~FL_SLEEP;

662 663 664 665
	switch (error) {
	case 0:
		break;
	case -EAGAIN:
Linus Torvalds's avatar
Linus Torvalds committed
666 667
		dprintk("lockd: lock still blocked\n");
		nlmsvc_insert_block(block, NLM_NEVER);
Marc Eshel's avatar
Marc Eshel committed
668
		nlmsvc_release_block(block);
669
		return;
670
	default:
Linus Torvalds's avatar
Linus Torvalds committed
671 672 673
		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
674
		nlmsvc_release_block(block);
675
		return;
Linus Torvalds's avatar
Linus Torvalds committed
676 677 678 679 680 681 682 683 684 685 686
	}

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 */
687
	nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG, &nlmsvc_grant_ops);
Linus Torvalds's avatar
Linus Torvalds committed
688 689 690 691 692 693 694 695 696 697
}

/*
 * 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).
 */
698
static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
Linus Torvalds's avatar
Linus Torvalds committed
699
{
700
	struct nlm_rqst		*call = data;
701
	struct nlm_block	*block = call->a_block;
Linus Torvalds's avatar
Linus Torvalds committed
702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717
	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);
718 719
}

Adrian Bunk's avatar
Adrian Bunk committed
720
static void nlmsvc_grant_release(void *data)
721
{
722 723 724
	struct nlm_rqst		*call = data;

	nlmsvc_release_block(call->a_block);
Linus Torvalds's avatar
Linus Torvalds committed
725 726
}

727 728
static const struct rpc_call_ops nlmsvc_grant_ops = {
	.rpc_call_done = nlmsvc_grant_callback,
729
	.rpc_release = nlmsvc_grant_release,
730 731
};

Linus Torvalds's avatar
Linus Torvalds committed
732 733 734 735 736
/*
 * We received a GRANT_RES callback. Try to find the corresponding
 * block.
 */
void
Al Viro's avatar
Al Viro committed
737
nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
Linus Torvalds's avatar
Linus Torvalds committed
738 739 740
{
	struct nlm_block	*block;

741 742 743
	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
744 745
		return;

746
	if (block) {
Al Viro's avatar
Al Viro committed
747
		if (status == nlm_lck_denied_grace_period) {
Linus Torvalds's avatar
Linus Torvalds committed
748 749 750 751 752
			/* 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. */
753
			nlmsvc_unlink_block(block);
Linus Torvalds's avatar
Linus Torvalds committed
754 755
		}
	}
756
	nlmsvc_release_block(block);
Linus Torvalds's avatar
Linus Torvalds committed
757 758
}

Marc Eshel's avatar
Marc Eshel committed
759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775
/* 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
776 777 778 779 780 781 782 783
/*
 * 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)
{
784 785 786 787 788
	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
789 790 791

		if (block->b_when == NLM_NEVER)
			break;
792 793
	        if (time_after(block->b_when,jiffies)) {
			timeout = block->b_when - jiffies;
Linus Torvalds's avatar
Linus Torvalds committed
794
			break;
795 796
		}

J. Bruce Fields's avatar
J. Bruce Fields committed
797 798
		dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
			block, block->b_when);
Marc Eshel's avatar
Marc Eshel committed
799 800 801 802 803 804
		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
805 806
	}

807
	return timeout;
Linus Torvalds's avatar
Linus Torvalds committed
808
}