svclock.c 24 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
/*
 * 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>
32
#include <linux/kthread.h>
Linus Torvalds's avatar
Linus Torvalds committed
33 34 35 36 37 38 39 40 41

#define NLMDBG_FACILITY		NLMDBG_SVCLOCK

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

42
static void nlmsvc_release_block(struct nlm_block *block);
Linus Torvalds's avatar
Linus Torvalds committed
43
static void	nlmsvc_insert_block(struct nlm_block *block, unsigned long);
44
static void	nlmsvc_remove_block(struct nlm_block *block);
45

46 47
static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
static void nlmsvc_freegrantargs(struct nlm_rqst *call);
48
static const struct rpc_call_ops nlmsvc_grant_ops;
Linus Torvalds's avatar
Linus Torvalds committed
49 50 51 52

/*
 * The list of blocked locks to retry
 */
53
static LIST_HEAD(nlm_blocked);
Linus Torvalds's avatar
Linus Torvalds committed
54 55 56 57 58 59 60

/*
 * Insert a blocked lock into the global list
 */
static void
nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
{
61 62
	struct nlm_block *b;
	struct list_head *pos;
Linus Torvalds's avatar
Linus Torvalds committed
63 64

	dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
65 66 67 68 69 70 71
	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
72 73 74
	if (when != NLM_NEVER) {
		if ((when += jiffies) == NLM_NEVER)
			when ++;
75 76 77 78 79 80 81 82 83
		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
84

85
	list_add_tail(&block->b_list, pos);
Linus Torvalds's avatar
Linus Torvalds committed
86 87 88 89 90 91
	block->b_when = when;
}

/*
 * Remove a block from the global list
 */
92
static inline void
Linus Torvalds's avatar
Linus Torvalds committed
93 94
nlmsvc_remove_block(struct nlm_block *block)
{
95 96 97
	if (!list_empty(&block->b_list)) {
		list_del_init(&block->b_list);
		nlmsvc_release_block(block);
Linus Torvalds's avatar
Linus Torvalds committed
98 99 100 101
	}
}

/*
102
 * Find a block for a given lock
Linus Torvalds's avatar
Linus Torvalds committed
103 104
 */
static struct nlm_block *
105
nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
Linus Torvalds's avatar
Linus Torvalds committed
106
{
107
	struct nlm_block	*block;
Linus Torvalds's avatar
Linus Torvalds committed
108 109 110 111 112 113
	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);
114
	list_for_each_entry(block, &nlm_blocked, b_list) {
115
		fl = &block->b_call->a_args.lock.fl;
Linus Torvalds's avatar
Linus Torvalds committed
116 117 118 119
		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,
120
				nlmdbg_cookie2a(&block->b_call->a_args.cookie));
Linus Torvalds's avatar
Linus Torvalds committed
121
		if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
122
			kref_get(&block->b_count);
Linus Torvalds's avatar
Linus Torvalds committed
123 124 125 126 127 128 129 130 131
			return block;
		}
	}

	return NULL;
}

static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
{
132
	if (a->len != b->len)
Linus Torvalds's avatar
Linus Torvalds committed
133
		return 0;
134
	if (memcmp(a->data, b->data, a->len))
Linus Torvalds's avatar
Linus Torvalds committed
135 136 137 138 139 140 141 142
		return 0;
	return 1;
}

/*
 * Find a block with a given NLM cookie.
 */
static inline struct nlm_block *
143
nlmsvc_find_block(struct nlm_cookie *cookie)
Linus Torvalds's avatar
Linus Torvalds committed
144 145 146
{
	struct nlm_block *block;

147
	list_for_each_entry(block, &nlm_blocked, b_list) {
148
		if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
149
			goto found;
Linus Torvalds's avatar
Linus Torvalds committed
150 151
	}

152 153 154
	return NULL;

found:
155
	dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
156
	kref_get(&block->b_count);
Linus Torvalds's avatar
Linus Torvalds committed
157 158 159 160 161 162 163 164 165 166 167 168
	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.
169 170 171 172 173
 *
 * 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
174
 */
175 176 177 178
static struct nlm_block *
nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
		    struct nlm_file *file, struct nlm_lock *lock,
		    struct nlm_cookie *cookie)
Linus Torvalds's avatar
Linus Torvalds committed
179 180
{
	struct nlm_block	*block;
181
	struct nlm_rqst		*call = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
182

183
	nlm_get_host(host);
184 185 186 187
	call = nlm_alloc_call(host);
	if (call == NULL)
		return NULL;

Linus Torvalds's avatar
Linus Torvalds committed
188
	/* Allocate memory for block, and initialize arguments */
189 190
	block = kzalloc(sizeof(*block), GFP_KERNEL);
	if (block == NULL)
Linus Torvalds's avatar
Linus Torvalds committed
191
		goto failed;
192
	kref_init(&block->b_count);
193 194
	INIT_LIST_HEAD(&block->b_list);
	INIT_LIST_HEAD(&block->b_flist);
Linus Torvalds's avatar
Linus Torvalds committed
195

196
	if (!nlmsvc_setgrantargs(call, lock))
Linus Torvalds's avatar
Linus Torvalds committed
197 198 199
		goto failed_free;

	/* Set notifier function for VFS, and init args */
200 201
	call->a_args.lock.fl.fl_flags |= FL_SLEEP;
	call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
202
	nlmclnt_next_cookie(&call->a_args.cookie);
Linus Torvalds's avatar
Linus Torvalds committed
203 204 205 206 207 208 209

	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
210
	block->b_fl = NULL;
211
	file->f_count++;
Linus Torvalds's avatar
Linus Torvalds committed
212 213

	/* Add to file's list of blocks */
214
	list_add(&block->b_flist, &file->f_blocks);
Linus Torvalds's avatar
Linus Torvalds committed
215 216

	/* Set up RPC arguments for callback */
217
	block->b_call = call;
Linus Torvalds's avatar
Linus Torvalds committed
218
	call->a_flags   = RPC_TASK_ASYNC;
219
	call->a_block = block;
Linus Torvalds's avatar
Linus Torvalds committed
220 221 222 223 224 225

	return block;

failed_free:
	kfree(block);
failed:
226
	nlm_release_call(call);
Linus Torvalds's avatar
Linus Torvalds committed
227 228 229 230
	return NULL;
}

/*
231
 * Delete a block.
Linus Torvalds's avatar
Linus Torvalds committed
232 233 234
 * It is the caller's responsibility to check whether the file
 * can be closed hereafter.
 */
235
static int nlmsvc_unlink_block(struct nlm_block *block)
Linus Torvalds's avatar
Linus Torvalds committed
236
{
237
	int status;
238
	dprintk("lockd: unlinking block %p...\n", block);
Linus Torvalds's avatar
Linus Torvalds committed
239 240

	/* Remove block from list */
241
	status = posix_unblock_lock(block->b_file->f_file, &block->b_call->a_args.lock.fl);
Linus Torvalds's avatar
Linus Torvalds committed
242
	nlmsvc_remove_block(block);
243 244
	return status;
}
Linus Torvalds's avatar
Linus Torvalds committed
245

246 247 248 249 250 251
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
252 253

	/* Remove block from file's list of blocks */
254
	mutex_lock(&file->f_mutex);
255
	list_del_init(&block->b_flist);
256
	mutex_unlock(&file->f_mutex);
Linus Torvalds's avatar
Linus Torvalds committed
257

258 259
	nlmsvc_freegrantargs(block->b_call);
	nlm_release_call(block->b_call);
260
	nlm_release_file(block->b_file);
Marc Eshel's avatar
Marc Eshel committed
261
	kfree(block->b_fl);
Linus Torvalds's avatar
Linus Torvalds committed
262
	kfree(block);
263 264 265 266 267 268
}

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
269 270
}

271 272 273 274 275 276 277
/*
 * 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)
278
{
279
	struct nlm_block *block, *next;
280 281

restart:
282
	mutex_lock(&file->f_mutex);
283
	list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
284
		if (!match(block->b_host, host))
285
			continue;
286 287 288
		/* Do not destroy blocks that are not on
		 * the global retry list - why? */
		if (list_empty(&block->b_list))
289 290
			continue;
		kref_get(&block->b_count);
291
		mutex_unlock(&file->f_mutex);
292 293 294 295
		nlmsvc_unlink_block(block);
		nlmsvc_release_block(block);
		goto restart;
	}
296
	mutex_unlock(&file->f_mutex);
297 298
}

299 300 301 302 303 304 305 306
/*
 * 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));
307
	call->a_args.lock.caller = utsname()->nodename;
308 309 310 311 312 313 314 315
	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);
316
		if (!data)
317 318 319 320 321 322 323 324 325 326
			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)
{
327
	if (call->a_args.lock.oh.data != call->a_owner)
328 329 330
		kfree(call->a_args.lock.oh.data);
}

331 332 333
/*
 * Deferred lock request handling for non-blocking lock
 */
334
static __be32
335 336
nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
{
337
	__be32 status = nlm_lck_denied_nolocks;
338 339 340 341 342 343 344 345 346 347 348 349 350

	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",
351
		block, block->b_flags, ntohl(status));
352 353 354 355

	return status;
}

Linus Torvalds's avatar
Linus Torvalds committed
356 357 358 359
/*
 * Attempt to establish a lock, and if it can't be granted, block it
 * if required.
 */
Al Viro's avatar
Al Viro committed
360
__be32
Linus Torvalds's avatar
Linus Torvalds committed
361
nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
362 363
	    struct nlm_host *host, struct nlm_lock *lock, int wait,
	    struct nlm_cookie *cookie)
Linus Torvalds's avatar
Linus Torvalds committed
364
{
365
	struct nlm_block	*block = NULL;
Linus Torvalds's avatar
Linus Torvalds committed
366
	int			error;
Al Viro's avatar
Al Viro committed
367
	__be32			ret;
Linus Torvalds's avatar
Linus Torvalds committed
368 369

	dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
370 371
				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
372 373 374 375 376 377
				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 */
378
	mutex_lock(&file->f_mutex);
379 380 381
	/* Get existing block (in case client is busy-waiting)
	 * or create new block
	 */
382
	block = nlmsvc_lookup_block(file, lock);
383
	if (block == NULL) {
384
		block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
385 386 387
		ret = nlm_lck_denied_nolocks;
		if (block == NULL)
			goto out;
388
		lock = &block->b_call->a_args.lock;
389 390
	} else
		lock->fl.fl_flags &= ~FL_SLEEP;
Linus Torvalds's avatar
Linus Torvalds committed
391

392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407
	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
408

409 410 411 412
	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;
413

414
	dprintk("lockd: vfs_lock_file returned %d\n", error);
415
	switch (error) {
Linus Torvalds's avatar
Linus Torvalds committed
416
		case 0:
Andy Adamson's avatar
Andy Adamson committed
417 418
			ret = nlm_granted;
			goto out;
419
		case -EAGAIN:
420
			ret = nlm_lck_denied;
421
			break;
422 423 424 425 426 427 428
		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;
429
		case -EDEADLK:
Andy Adamson's avatar
Andy Adamson committed
430 431
			ret = nlm_deadlock;
			goto out;
Linus Torvalds's avatar
Linus Torvalds committed
432
		default:			/* includes ENOLCK */
Andy Adamson's avatar
Andy Adamson committed
433 434
			ret = nlm_lck_denied_nolocks;
			goto out;
Linus Torvalds's avatar
Linus Torvalds committed
435 436
	}

437 438 439 440 441
	ret = nlm_lck_denied;
	if (!wait)
		goto out;

	ret = nlm_lck_blocked;
Linus Torvalds's avatar
Linus Torvalds committed
442 443

	/* Append to list of blocked */
444
	nlmsvc_insert_block(block, NLM_NEVER);
Andy Adamson's avatar
Andy Adamson committed
445
out:
446
	mutex_unlock(&file->f_mutex);
447
	nlmsvc_release_block(block);
Andy Adamson's avatar
Andy Adamson committed
448 449
	dprintk("lockd: nlmsvc_lock returned %u\n", ret);
	return ret;
Linus Torvalds's avatar
Linus Torvalds committed
450 451 452 453 454
}

/*
 * Test for presence of a conflicting lock.
 */
Al Viro's avatar
Al Viro committed
455
__be32
456
nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
457 458
		struct nlm_host *host, struct nlm_lock *lock,
		struct nlm_lock *conflock, struct nlm_cookie *cookie)
Linus Torvalds's avatar
Linus Torvalds committed
459
{
Marc Eshel's avatar
Marc Eshel committed
460 461 462 463
	struct nlm_block 	*block = NULL;
	int			error;
	__be32			ret;

Linus Torvalds's avatar
Linus Torvalds committed
464
	dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
465 466
				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
467 468 469 470
				lock->fl.fl_type,
				(long long)lock->fl.fl_start,
				(long long)lock->fl.fl_end);

Marc Eshel's avatar
Marc Eshel committed
471 472 473 474 475 476 477 478
	/* 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;
479
		block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
Marc Eshel's avatar
Marc Eshel committed
480 481 482 483 484 485 486 487 488 489 490
		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);
491 492
			ret = nlm_lck_denied;
			goto out;
Marc Eshel's avatar
Marc Eshel committed
493 494
		}
		if (block->b_flags & B_GOT_CALLBACK) {
495
			nlmsvc_unlink_block(block);
Marc Eshel's avatar
Marc Eshel committed
496 497 498 499
			if (block->b_fl != NULL
					&& block->b_fl->fl_type != F_UNLCK) {
				lock->fl = *block->b_fl;
				goto conf_lock;
500 501 502
			} else {
				ret = nlm_granted;
				goto out;
Marc Eshel's avatar
Marc Eshel committed
503 504
			}
		}
505 506
		ret = nlm_drop_reply;
		goto out;
Linus Torvalds's avatar
Linus Torvalds committed
507 508
	}

Marc Eshel's avatar
Marc Eshel committed
509
	error = vfs_test_lock(file->f_file, &lock->fl);
510 511 512 513
	if (error == -EINPROGRESS) {
		ret = nlmsvc_defer_lock_rqst(rqstp, block);
		goto out;
	}
Marc Eshel's avatar
Marc Eshel committed
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
	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
/*
 * 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)
622
			__locks_copy_lock(block->b_fl, conf);
Marc Eshel's avatar
Marc Eshel committed
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
	}
}

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
		printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
742
				-error, __func__);
Linus Torvalds's avatar
Linus Torvalds committed
743
		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
	}

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

753 754 755 756
	/* keep block on the list, but don't reattempt until the RPC
	 * completes or the submission fails
	 */
	nlmsvc_insert_block(block, NLM_NEVER);
Linus Torvalds's avatar
Linus Torvalds committed
757

758 759 760 761 762 763 764 765 766
	/* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
	 * will queue up a new one if this one times out
	 */
	error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
				&nlmsvc_grant_ops);

	/* RPC submission failed, wait a bit and retry */
	if (error < 0)
		nlmsvc_insert_block(block, 10 * HZ);
Linus Torvalds's avatar
Linus Torvalds committed
767 768 769 770 771 772 773 774 775 776
}

/*
 * 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).
 */
777
static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
Linus Torvalds's avatar
Linus Torvalds committed
778
{
779
	struct nlm_rqst		*call = data;
780
	struct nlm_block	*block = call->a_block;
Linus Torvalds's avatar
Linus Torvalds committed
781 782 783 784
	unsigned long		timeout;

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

785
	lock_kernel();
786 787 788 789 790 791 792 793 794
	/* if the block is not on a list at this point then it has
	 * been invalidated. Don't try to requeue it.
	 *
	 * FIXME: it's possible that the block is removed from the list
	 * after this check but before the nlmsvc_insert_block. In that
	 * case it will be added back. Perhaps we need better locking
	 * for nlm_blocked?
	 */
	if (list_empty(&block->b_list))
795
		goto out;
796

Linus Torvalds's avatar
Linus Torvalds committed
797 798 799 800 801 802 803 804 805 806 807 808
	/* 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);
809 810
out:
	unlock_kernel();
811 812
}

Adrian Bunk's avatar
Adrian Bunk committed
813
static void nlmsvc_grant_release(void *data)
814
{
815 816
	struct nlm_rqst		*call = data;

817
	lock_kernel();
818
	nlmsvc_release_block(call->a_block);
819
	unlock_kernel();
Linus Torvalds's avatar
Linus Torvalds committed
820 821
}

822 823
static const struct rpc_call_ops nlmsvc_grant_ops = {
	.rpc_call_done = nlmsvc_grant_callback,
824
	.rpc_release = nlmsvc_grant_release,
825 826
};

Linus Torvalds's avatar
Linus Torvalds committed
827 828 829 830 831
/*
 * We received a GRANT_RES callback. Try to find the corresponding
 * block.
 */
void
Al Viro's avatar
Al Viro committed
832
nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
Linus Torvalds's avatar
Linus Torvalds committed
833 834 835
{
	struct nlm_block	*block;

836 837 838
	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
839 840
		return;

841
	if (block) {
Al Viro's avatar
Al Viro committed
842
		if (status == nlm_lck_denied_grace_period) {
Linus Torvalds's avatar
Linus Torvalds committed
843 844 845 846 847
			/* 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. */
848
			nlmsvc_unlink_block(block);
Linus Torvalds's avatar
Linus Torvalds committed
849 850
		}
	}
851
	nlmsvc_release_block(block);
Linus Torvalds's avatar
Linus Torvalds committed
852 853
}

Marc Eshel's avatar
Marc Eshel committed
854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870
/* 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
871 872 873 874 875 876 877 878
/*
 * 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)
{
879 880 881
	unsigned long	timeout = MAX_SCHEDULE_TIMEOUT;
	struct nlm_block *block;

882
	while (!list_empty(&nlm_blocked) && !kthread_should_stop()) {
883
		block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
Linus Torvalds's avatar
Linus Torvalds committed
884 885 886

		if (block->b_when == NLM_NEVER)
			break;
887
		if (time_after(block->b_when, jiffies)) {
888
			timeout = block->b_when - jiffies;
Linus Torvalds's avatar
Linus Torvalds committed
889
			break;
890 891
		}

J. Bruce Fields's avatar
J. Bruce Fields committed
892 893
		dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
			block, block->b_when);
Marc Eshel's avatar
Marc Eshel committed
894 895 896 897 898 899
		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
900 901
	}

902
	return timeout;
Linus Torvalds's avatar
Linus Torvalds committed
903
}