glock.c 46.6 KB
Newer Older
David Teigland's avatar
David Teigland committed
1 2
/*
 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
3
 * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
David Teigland's avatar
David Teigland committed
4 5 6
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
7
 * of the GNU General Public License version 2.
David Teigland's avatar
David Teigland committed
8 9 10 11 12 13 14 15 16 17
 */

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
#include <linux/buffer_head.h>
#include <linux/delay.h>
#include <linux/sort.h>
#include <linux/jhash.h>
18
#include <linux/kallsyms.h>
19
#include <linux/gfs2_ondisk.h>
20
#include <linux/list.h>
21
#include <linux/lm_interface.h>
22
#include <linux/wait.h>
akpm@linux-foundation.org's avatar
akpm@linux-foundation.org committed
23
#include <linux/module.h>
24
#include <linux/rwsem.h>
David Teigland's avatar
David Teigland committed
25
#include <asm/uaccess.h>
26 27
#include <linux/seq_file.h>
#include <linux/debugfs.h>
28 29
#include <linux/kthread.h>
#include <linux/freezer.h>
30 31
#include <linux/workqueue.h>
#include <linux/jiffies.h>
David Teigland's avatar
David Teigland committed
32 33

#include "gfs2.h"
34
#include "incore.h"
David Teigland's avatar
David Teigland committed
35 36 37 38 39 40 41
#include "glock.h"
#include "glops.h"
#include "inode.h"
#include "lops.h"
#include "meta_io.h"
#include "quota.h"
#include "super.h"
42
#include "util.h"
43
#include "bmap.h"
David Teigland's avatar
David Teigland committed
44

45
struct gfs2_gl_hash_bucket {
46
        struct hlist_head hb_list;
47 48
};

49 50 51 52 53
struct gfs2_glock_iter {
	int hash;			/* hash bucket index         */
	struct gfs2_sbd *sdp;		/* incore superblock         */
	struct gfs2_glock *gl;		/* current glock struct      */
	char string[512];		/* scratch space             */
54 55
};

David Teigland's avatar
David Teigland committed
56 57
typedef void (*glock_examiner) (struct gfs2_glock * gl);

58
static int gfs2_dump_lockstate(struct gfs2_sbd *sdp);
59 60 61
static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl);
#define GLOCK_BUG_ON(gl,x) do { if (unlikely(x)) { __dump_glock(NULL, gl); BUG(); } } while(0)
static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
62

63
static DECLARE_RWSEM(gfs2_umount_flush_sem);
64
static struct dentry *gfs2_root;
65
static struct workqueue_struct *glock_workqueue;
66 67
static LIST_HEAD(lru_list);
static atomic_t lru_count = ATOMIC_INIT(0);
Julia Lawall's avatar
Julia Lawall committed
68
static DEFINE_SPINLOCK(lru_lock);
69

70
#define GFS2_GL_HASH_SHIFT      15
71 72 73
#define GFS2_GL_HASH_SIZE       (1 << GFS2_GL_HASH_SHIFT)
#define GFS2_GL_HASH_MASK       (GFS2_GL_HASH_SIZE - 1)

74
static struct gfs2_gl_hash_bucket gl_hash_table[GFS2_GL_HASH_SIZE];
75
static struct dentry *gfs2_root;
76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115

/*
 * Despite what you might think, the numbers below are not arbitrary :-)
 * They are taken from the ipv4 routing hash code, which is well tested
 * and thus should be nearly optimal. Later on we might tweek the numbers
 * but for now this should be fine.
 *
 * The reason for putting the locks in a separate array from the list heads
 * is that we can have fewer locks than list heads and save memory. We use
 * the same hash function for both, but with a different hash mask.
 */
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) || \
	defined(CONFIG_PROVE_LOCKING)

#ifdef CONFIG_LOCKDEP
# define GL_HASH_LOCK_SZ        256
#else
# if NR_CPUS >= 32
#  define GL_HASH_LOCK_SZ       4096
# elif NR_CPUS >= 16
#  define GL_HASH_LOCK_SZ       2048
# elif NR_CPUS >= 8
#  define GL_HASH_LOCK_SZ       1024
# elif NR_CPUS >= 4
#  define GL_HASH_LOCK_SZ       512
# else
#  define GL_HASH_LOCK_SZ       256
# endif
#endif

/* We never want more locks than chains */
#if GFS2_GL_HASH_SIZE < GL_HASH_LOCK_SZ
# undef GL_HASH_LOCK_SZ
# define GL_HASH_LOCK_SZ GFS2_GL_HASH_SIZE
#endif

static rwlock_t gl_hash_locks[GL_HASH_LOCK_SZ];

static inline rwlock_t *gl_lock_addr(unsigned int x)
{
116
	return &gl_hash_locks[x & (GL_HASH_LOCK_SZ-1)];
117 118
}
#else /* not SMP, so no spinlocks required */
Randy Dunlap's avatar
Randy Dunlap committed
119
static inline rwlock_t *gl_lock_addr(unsigned int x)
120 121 122 123
{
	return NULL;
}
#endif
124

David Teigland's avatar
David Teigland committed
125 126 127 128 129 130 131
/**
 * gl_hash() - Turn glock number into hash bucket number
 * @lock: The glock number
 *
 * Returns: The number of the corresponding hash bucket
 */

132 133
static unsigned int gl_hash(const struct gfs2_sbd *sdp,
			    const struct lm_lockname *name)
David Teigland's avatar
David Teigland committed
134 135 136
{
	unsigned int h;

137
	h = jhash(&name->ln_number, sizeof(u64), 0);
David Teigland's avatar
David Teigland committed
138
	h = jhash(&name->ln_type, sizeof(unsigned int), h);
139
	h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
David Teigland's avatar
David Teigland committed
140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157
	h &= GFS2_GL_HASH_MASK;

	return h;
}

/**
 * glock_free() - Perform a few checks and then release struct gfs2_glock
 * @gl: The glock to release
 *
 * Also calls lock module to release its internal structure for this glock.
 *
 */

static void glock_free(struct gfs2_glock *gl)
{
	struct gfs2_sbd *sdp = gl->gl_sbd;
	struct inode *aspace = gl->gl_aspace;

Steven Whitehouse's avatar
Steven Whitehouse committed
158
	if (sdp->sd_lockstruct.ls_ops->lm_put_lock)
159
		sdp->sd_lockstruct.ls_ops->lm_put_lock(gl->gl_lock);
David Teigland's avatar
David Teigland committed
160 161 162 163 164 165 166 167 168 169 170 171 172

	if (aspace)
		gfs2_aspace_put(aspace);

	kmem_cache_free(gfs2_glock_cachep, gl);
}

/**
 * gfs2_glock_hold() - increment reference count on glock
 * @gl: The glock to hold
 *
 */

173
static void gfs2_glock_hold(struct gfs2_glock *gl)
David Teigland's avatar
David Teigland committed
174
{
175
	atomic_inc(&gl->gl_ref);
David Teigland's avatar
David Teigland committed
176 177
}

178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193
/**
 * gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
 * @gl: the glock
 *
 */

static void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
{
	spin_lock(&lru_lock);
	if (list_empty(&gl->gl_lru) && gl->gl_state != LM_ST_UNLOCKED) {
		list_add_tail(&gl->gl_lru, &lru_list);
		atomic_inc(&lru_count);
	}
	spin_unlock(&lru_lock);
}

David Teigland's avatar
David Teigland committed
194 195 196 197 198 199 200 201 202 203
/**
 * gfs2_glock_put() - Decrement reference count on glock
 * @gl: The glock to put
 *
 */

int gfs2_glock_put(struct gfs2_glock *gl)
{
	int rv = 0;

204
	write_lock(gl_lock_addr(gl->gl_hash));
205
	if (atomic_dec_and_test(&gl->gl_ref)) {
206
		hlist_del(&gl->gl_list);
207
		write_unlock(gl_lock_addr(gl->gl_hash));
208 209 210 211 212 213
		spin_lock(&lru_lock);
		if (!list_empty(&gl->gl_lru)) {
			list_del_init(&gl->gl_lru);
			atomic_dec(&lru_count);
		}
		spin_unlock(&lru_lock);
214
		GLOCK_BUG_ON(gl, gl->gl_state != LM_ST_UNLOCKED);
215
		GLOCK_BUG_ON(gl, !list_empty(&gl->gl_lru));
216
		GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
David Teigland's avatar
David Teigland committed
217 218 219 220
		glock_free(gl);
		rv = 1;
		goto out;
	}
221
	write_unlock(gl_lock_addr(gl->gl_hash));
222 223 224
	/* 1 for being hashed, 1 for having state != LM_ST_UNLOCKED */
	if (atomic_read(&gl->gl_ref) == 2)
		gfs2_glock_schedule_for_reclaim(gl);
225
out:
David Teigland's avatar
David Teigland committed
226 227 228 229 230 231 232 233 234 235 236
	return rv;
}

/**
 * search_bucket() - Find struct gfs2_glock by lock number
 * @bucket: the bucket to search
 * @name: The lock name
 *
 * Returns: NULL, or the struct gfs2_glock with the requested number
 */

237
static struct gfs2_glock *search_bucket(unsigned int hash,
238
					const struct gfs2_sbd *sdp,
239
					const struct lm_lockname *name)
David Teigland's avatar
David Teigland committed
240 241
{
	struct gfs2_glock *gl;
242
	struct hlist_node *h;
David Teigland's avatar
David Teigland committed
243

244
	hlist_for_each_entry(gl, h, &gl_hash_table[hash].hb_list, gl_list) {
David Teigland's avatar
David Teigland committed
245 246
		if (!lm_name_equal(&gl->gl_name, name))
			continue;
247 248
		if (gl->gl_sbd != sdp)
			continue;
David Teigland's avatar
David Teigland committed
249

250
		atomic_inc(&gl->gl_ref);
David Teigland's avatar
David Teigland committed
251 252 253 254 255 256 257 258 259 260 261 262 263 264 265

		return gl;
	}

	return NULL;
}

/**
 * gfs2_glock_find() - Find glock by lock number
 * @sdp: The GFS2 superblock
 * @name: The lock name
 *
 * Returns: NULL, or the struct gfs2_glock with the requested number
 */

266
static struct gfs2_glock *gfs2_glock_find(const struct gfs2_sbd *sdp,
267
					  const struct lm_lockname *name)
David Teigland's avatar
David Teigland committed
268
{
269
	unsigned int hash = gl_hash(sdp, name);
David Teigland's avatar
David Teigland committed
270 271
	struct gfs2_glock *gl;

272
	read_lock(gl_lock_addr(hash));
273
	gl = search_bucket(hash, sdp, name);
274
	read_unlock(gl_lock_addr(hash));
David Teigland's avatar
David Teigland committed
275 276 277 278

	return gl;
}

279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296
/**
 * may_grant - check if its ok to grant a new lock
 * @gl: The glock
 * @gh: The lock request which we wish to grant
 *
 * Returns: true if its ok to grant the lock
 */

static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
{
	const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
	if ((gh->gh_state == LM_ST_EXCLUSIVE ||
	     gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
		return 0;
	if (gl->gl_state == gh->gh_state)
		return 1;
	if (gh->gh_flags & GL_EXACT)
		return 0;
297 298 299 300 301 302
	if (gl->gl_state == LM_ST_EXCLUSIVE) {
		if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
			return 1;
		if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
			return 1;
	}
303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318
	if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
		return 1;
	return 0;
}

static void gfs2_holder_wake(struct gfs2_holder *gh)
{
	clear_bit(HIF_WAIT, &gh->gh_iflags);
	smp_mb__after_clear_bit();
	wake_up_bit(&gh->gh_iflags, HIF_WAIT);
}

/**
 * do_promote - promote as many requests as possible on the current queue
 * @gl: The glock
 * 
319 320
 * Returns: 1 if there is a blocked holder at the head of the list, or 2
 *          if a type specific operation is underway.
321 322 323
 */

static int do_promote(struct gfs2_glock *gl)
324 325
__releases(&gl->gl_spin)
__acquires(&gl->gl_spin)
326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342
{
	const struct gfs2_glock_operations *glops = gl->gl_ops;
	struct gfs2_holder *gh, *tmp;
	int ret;

restart:
	list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
		if (test_bit(HIF_HOLDER, &gh->gh_iflags))
			continue;
		if (may_grant(gl, gh)) {
			if (gh->gh_list.prev == &gl->gl_holders &&
			    glops->go_lock) {
				spin_unlock(&gl->gl_spin);
				/* FIXME: eliminate this eventually */
				ret = glops->go_lock(gh);
				spin_lock(&gl->gl_spin);
				if (ret) {
343 344
					if (ret == 1)
						return 2;
345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448
					gh->gh_error = ret;
					list_del_init(&gh->gh_list);
					gfs2_holder_wake(gh);
					goto restart;
				}
				set_bit(HIF_HOLDER, &gh->gh_iflags);
				gfs2_holder_wake(gh);
				goto restart;
			}
			set_bit(HIF_HOLDER, &gh->gh_iflags);
			gfs2_holder_wake(gh);
			continue;
		}
		if (gh->gh_list.prev == &gl->gl_holders)
			return 1;
		break;
	}
	return 0;
}

/**
 * do_error - Something unexpected has happened during a lock request
 *
 */

static inline void do_error(struct gfs2_glock *gl, const int ret)
{
	struct gfs2_holder *gh, *tmp;

	list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
		if (test_bit(HIF_HOLDER, &gh->gh_iflags))
			continue;
		if (ret & LM_OUT_ERROR)
			gh->gh_error = -EIO;
		else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
			gh->gh_error = GLR_TRYFAILED;
		else
			continue;
		list_del_init(&gh->gh_list);
		gfs2_holder_wake(gh);
	}
}

/**
 * find_first_waiter - find the first gh that's waiting for the glock
 * @gl: the glock
 */

static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
{
	struct gfs2_holder *gh;

	list_for_each_entry(gh, &gl->gl_holders, gh_list) {
		if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
			return gh;
	}
	return NULL;
}

/**
 * state_change - record that the glock is now in a different state
 * @gl: the glock
 * @new_state the new state
 *
 */

static void state_change(struct gfs2_glock *gl, unsigned int new_state)
{
	int held1, held2;

	held1 = (gl->gl_state != LM_ST_UNLOCKED);
	held2 = (new_state != LM_ST_UNLOCKED);

	if (held1 != held2) {
		if (held2)
			gfs2_glock_hold(gl);
		else
			gfs2_glock_put(gl);
	}

	gl->gl_state = new_state;
	gl->gl_tchange = jiffies;
}

static void gfs2_demote_wake(struct gfs2_glock *gl)
{
	gl->gl_demote_state = LM_ST_EXCLUSIVE;
	clear_bit(GLF_DEMOTE, &gl->gl_flags);
	smp_mb__after_clear_bit();
	wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
}

/**
 * finish_xmote - The DLM has replied to one of our lock requests
 * @gl: The glock
 * @ret: The status from the DLM
 *
 */

static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
{
	const struct gfs2_glock_operations *glops = gl->gl_ops;
	struct gfs2_holder *gh;
	unsigned state = ret & LM_OUT_ST_MASK;
449
	int rv;
450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513

	spin_lock(&gl->gl_spin);
	state_change(gl, state);
	gh = find_first_waiter(gl);

	/* Demote to UN request arrived during demote to SH or DF */
	if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
	    state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
		gl->gl_target = LM_ST_UNLOCKED;

	/* Check for state != intended state */
	if (unlikely(state != gl->gl_target)) {
		if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
			/* move to back of queue and try next entry */
			if (ret & LM_OUT_CANCELED) {
				if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
					list_move_tail(&gh->gh_list, &gl->gl_holders);
				gh = find_first_waiter(gl);
				gl->gl_target = gh->gh_state;
				goto retry;
			}
			/* Some error or failed "try lock" - report it */
			if ((ret & LM_OUT_ERROR) ||
			    (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
				gl->gl_target = gl->gl_state;
				do_error(gl, ret);
				goto out;
			}
		}
		switch(state) {
		/* Unlocked due to conversion deadlock, try again */
		case LM_ST_UNLOCKED:
retry:
			do_xmote(gl, gh, gl->gl_target);
			break;
		/* Conversion fails, unlock and try again */
		case LM_ST_SHARED:
		case LM_ST_DEFERRED:
			do_xmote(gl, gh, LM_ST_UNLOCKED);
			break;
		default: /* Everything else */
			printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
			GLOCK_BUG_ON(gl, 1);
		}
		spin_unlock(&gl->gl_spin);
		gfs2_glock_put(gl);
		return;
	}

	/* Fast path - we got what we asked for */
	if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
		gfs2_demote_wake(gl);
	if (state != LM_ST_UNLOCKED) {
		if (glops->go_xmote_bh) {
			spin_unlock(&gl->gl_spin);
			rv = glops->go_xmote_bh(gl, gh);
			if (rv == -EAGAIN)
				return;
			spin_lock(&gl->gl_spin);
			if (rv) {
				do_error(gl, rv);
				goto out;
			}
		}
514 515 516
		rv = do_promote(gl);
		if (rv == 2)
			goto out_locked;
517 518 519
	}
out:
	clear_bit(GLF_LOCK, &gl->gl_flags);
520
out_locked:
521 522 523 524 525 526 527 528 529
	spin_unlock(&gl->gl_spin);
	gfs2_glock_put(gl);
}

static unsigned int gfs2_lm_lock(struct gfs2_sbd *sdp, void *lock,
				 unsigned int cur_state, unsigned int req_state,
				 unsigned int flags)
{
	int ret = LM_OUT_ERROR;
Steven Whitehouse's avatar
Steven Whitehouse committed
530 531 532 533

	if (!sdp->sd_lockstruct.ls_ops->lm_lock)
		return req_state == LM_ST_UNLOCKED ? 0 : req_state;

534 535 536 537 538 539 540 541 542 543 544 545 546 547 548
	if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
		ret = sdp->sd_lockstruct.ls_ops->lm_lock(lock, cur_state,
							 req_state, flags);
	return ret;
}

/**
 * do_xmote - Calls the DLM to change the state of a lock
 * @gl: The lock state
 * @gh: The holder (only for promotes)
 * @target: The target lock state
 *
 */

static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
549 550
__releases(&gl->gl_spin)
__acquires(&gl->gl_spin)
551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615
{
	const struct gfs2_glock_operations *glops = gl->gl_ops;
	struct gfs2_sbd *sdp = gl->gl_sbd;
	unsigned int lck_flags = gh ? gh->gh_flags : 0;
	int ret;

	lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
		      LM_FLAG_PRIORITY);
	BUG_ON(gl->gl_state == target);
	BUG_ON(gl->gl_state == gl->gl_target);
	if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
	    glops->go_inval) {
		set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
		do_error(gl, 0); /* Fail queued try locks */
	}
	spin_unlock(&gl->gl_spin);
	if (glops->go_xmote_th)
		glops->go_xmote_th(gl);
	if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
		glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
	clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);

	gfs2_glock_hold(gl);
	if (target != LM_ST_UNLOCKED && (gl->gl_state == LM_ST_SHARED ||
	    gl->gl_state == LM_ST_DEFERRED) &&
	    !(lck_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
		lck_flags |= LM_FLAG_TRY_1CB;
	ret = gfs2_lm_lock(sdp, gl->gl_lock, gl->gl_state, target, lck_flags);

	if (!(ret & LM_OUT_ASYNC)) {
		finish_xmote(gl, ret);
		gfs2_glock_hold(gl);
		if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
			gfs2_glock_put(gl);
	} else {
		GLOCK_BUG_ON(gl, ret != LM_OUT_ASYNC);
	}
	spin_lock(&gl->gl_spin);
}

/**
 * find_first_holder - find the first "holder" gh
 * @gl: the glock
 */

static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
{
	struct gfs2_holder *gh;

	if (!list_empty(&gl->gl_holders)) {
		gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
		if (test_bit(HIF_HOLDER, &gh->gh_iflags))
			return gh;
	}
	return NULL;
}

/**
 * run_queue - do all outstanding tasks related to a glock
 * @gl: The glock in question
 * @nonblock: True if we must not block in run_queue
 *
 */

static void run_queue(struct gfs2_glock *gl, const int nonblock)
616 617
__releases(&gl->gl_spin)
__acquires(&gl->gl_spin)
618 619
{
	struct gfs2_holder *gh = NULL;
620
	int ret;
621 622 623 624 625 626 627 628 629 630 631 632 633

	if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
		return;

	GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));

	if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
	    gl->gl_demote_state != gl->gl_state) {
		if (find_first_holder(gl))
			goto out;
		if (nonblock)
			goto out_sched;
		set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
634
		GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
635 636 637 638
		gl->gl_target = gl->gl_demote_state;
	} else {
		if (test_bit(GLF_DEMOTE, &gl->gl_flags))
			gfs2_demote_wake(gl);
639 640
		ret = do_promote(gl);
		if (ret == 0)
641
			goto out;
642 643
		if (ret == 2)
			return;
644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659
		gh = find_first_waiter(gl);
		gl->gl_target = gh->gh_state;
		if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
			do_error(gl, 0); /* Fail queued try locks */
	}
	do_xmote(gl, gh, gl->gl_target);
	return;

out_sched:
	gfs2_glock_hold(gl);
	if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
		gfs2_glock_put(gl);
out:
	clear_bit(GLF_LOCK, &gl->gl_flags);
}

660 661
static void glock_work_func(struct work_struct *work)
{
662
	unsigned long delay = 0;
663 664
	struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);

665 666
	if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags))
		finish_xmote(gl, gl->gl_reply);
667
	spin_lock(&gl->gl_spin);
668 669 670
	if (test_and_clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
	    gl->gl_state != LM_ST_UNLOCKED &&
	    gl->gl_demote_state != LM_ST_EXCLUSIVE) {
671 672 673 674 675 676 677
		unsigned long holdtime, now = jiffies;
		holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
		if (time_before(now, holdtime))
			delay = holdtime - now;
		set_bit(delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE, &gl->gl_flags);
	}
	run_queue(gl, 0);
678
	spin_unlock(&gl->gl_spin);
679 680 681
	if (!delay ||
	    queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
		gfs2_glock_put(gl);
682 683
}

684 685 686 687
static int gfs2_lm_get_lock(struct gfs2_sbd *sdp, struct lm_lockname *name,
		     void **lockp)
{
	int error = -EIO;
Steven Whitehouse's avatar
Steven Whitehouse committed
688 689
	if (!sdp->sd_lockstruct.ls_ops->lm_get_lock)
		return 0;
690 691 692 693 694 695
	if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
		error = sdp->sd_lockstruct.ls_ops->lm_get_lock(
				sdp->sd_lockstruct.ls_lockspace, name, lockp);
	return error;
}

David Teigland's avatar
David Teigland committed
696 697 698 699 700 701 702 703 704 705 706 707 708
/**
 * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 * @sdp: The GFS2 superblock
 * @number: the lock number
 * @glops: The glock_operations to use
 * @create: If 0, don't create the glock if it doesn't exist
 * @glp: the glock is returned here
 *
 * This does not lock a glock, just finds/creates structures for one.
 *
 * Returns: errno
 */

709
int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
710
		   const struct gfs2_glock_operations *glops, int create,
David Teigland's avatar
David Teigland committed
711 712
		   struct gfs2_glock **glp)
{
713
	struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
David Teigland's avatar
David Teigland committed
714
	struct gfs2_glock *gl, *tmp;
715
	unsigned int hash = gl_hash(sdp, &name);
David Teigland's avatar
David Teigland committed
716 717
	int error;

718
	read_lock(gl_lock_addr(hash));
719
	gl = search_bucket(hash, sdp, &name);
720
	read_unlock(gl_lock_addr(hash));
David Teigland's avatar
David Teigland committed
721 722 723 724 725 726 727 728 729 730

	if (gl || !create) {
		*glp = gl;
		return 0;
	}

	gl = kmem_cache_alloc(gfs2_glock_cachep, GFP_KERNEL);
	if (!gl)
		return -ENOMEM;

731
	gl->gl_flags = 0;
David Teigland's avatar
David Teigland committed
732
	gl->gl_name = name;
733
	atomic_set(&gl->gl_ref, 1);
David Teigland's avatar
David Teigland committed
734
	gl->gl_state = LM_ST_UNLOCKED;
735
	gl->gl_target = LM_ST_UNLOCKED;
736
	gl->gl_demote_state = LM_ST_EXCLUSIVE;
737
	gl->gl_hash = hash;
David Teigland's avatar
David Teigland committed
738
	gl->gl_ops = glops;
739
	gl->gl_stamp = jiffies;
740
	gl->gl_tchange = jiffies;
741
	gl->gl_object = NULL;
David Teigland's avatar
David Teigland committed
742
	gl->gl_sbd = sdp;
743
	gl->gl_aspace = NULL;
744
	INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
David Teigland's avatar
David Teigland committed
745 746 747

	/* If this glock protects actual on-disk data or metadata blocks,
	   create a VFS inode to manage the pages/buffers holding them. */
748
	if (glops == &gfs2_inode_glops || glops == &gfs2_rgrp_glops) {
David Teigland's avatar
David Teigland committed
749 750 751 752 753 754 755 756 757 758 759
		gl->gl_aspace = gfs2_aspace_get(sdp);
		if (!gl->gl_aspace) {
			error = -ENOMEM;
			goto fail;
		}
	}

	error = gfs2_lm_get_lock(sdp, &name, &gl->gl_lock);
	if (error)
		goto fail_aspace;

760
	write_lock(gl_lock_addr(hash));
761
	tmp = search_bucket(hash, sdp, &name);
David Teigland's avatar
David Teigland committed
762
	if (tmp) {
763
		write_unlock(gl_lock_addr(hash));
David Teigland's avatar
David Teigland committed
764 765 766
		glock_free(gl);
		gl = tmp;
	} else {
767
		hlist_add_head(&gl->gl_list, &gl_hash_table[hash].hb_list);
768
		write_unlock(gl_lock_addr(hash));
David Teigland's avatar
David Teigland committed
769 770 771 772 773 774
	}

	*glp = gl;

	return 0;

775
fail_aspace:
David Teigland's avatar
David Teigland committed
776 777
	if (gl->gl_aspace)
		gfs2_aspace_put(gl->gl_aspace);
778
fail:
779
	kmem_cache_free(gfs2_glock_cachep, gl);
David Teigland's avatar
David Teigland committed
780 781 782 783 784 785 786 787 788 789 790 791
	return error;
}

/**
 * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 * @gl: the glock
 * @state: the state we're requesting
 * @flags: the modifier flags
 * @gh: the holder structure
 *
 */

792
void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
David Teigland's avatar
David Teigland committed
793 794 795 796
		      struct gfs2_holder *gh)
{
	INIT_LIST_HEAD(&gh->gh_list);
	gh->gh_gl = gl;
797
	gh->gh_ip = (unsigned long)__builtin_return_address(0);
798
	gh->gh_owner_pid = get_pid(task_pid(current));
David Teigland's avatar
David Teigland committed
799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815
	gh->gh_state = state;
	gh->gh_flags = flags;
	gh->gh_error = 0;
	gh->gh_iflags = 0;
	gfs2_glock_hold(gl);
}

/**
 * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 * @state: the state we're requesting
 * @flags: the modifier flags
 * @gh: the holder structure
 *
 * Don't mess with the glock.
 *
 */

816
void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
David Teigland's avatar
David Teigland committed
817 818
{
	gh->gh_state = state;
819
	gh->gh_flags = flags;
820
	gh->gh_iflags = 0;
821
	gh->gh_ip = (unsigned long)__builtin_return_address(0);
David Teigland's avatar
David Teigland committed
822 823 824 825 826 827 828 829 830 831
}

/**
 * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 * @gh: the holder structure
 *
 */

void gfs2_holder_uninit(struct gfs2_holder *gh)
{
832
	put_pid(gh->gh_owner_pid);
David Teigland's avatar
David Teigland committed
833 834
	gfs2_glock_put(gh->gh_gl);
	gh->gh_gl = NULL;
835
	gh->gh_ip = 0;
David Teigland's avatar
David Teigland committed
836 837
}

Abhijith Das's avatar
Abhijith Das committed
838
static int just_schedule(void *word)
839 840 841 842 843
{
        schedule();
        return 0;
}

844
static void wait_on_holder(struct gfs2_holder *gh)
845
{
846 847
	might_sleep();
	wait_on_bit(&gh->gh_iflags, HIF_WAIT, just_schedule, TASK_UNINTERRUPTIBLE);
848 849
}

850
static void wait_on_demote(struct gfs2_glock *gl)
David Teigland's avatar
David Teigland committed
851
{
852 853
	might_sleep();
	wait_on_bit(&gl->gl_flags, GLF_DEMOTE, just_schedule, TASK_UNINTERRUPTIBLE);
David Teigland's avatar
David Teigland committed
854 855 856
}

/**
857 858 859
 * handle_callback - process a demote request
 * @gl: the glock
 * @state: the state the caller wants us to change to
David Teigland's avatar
David Teigland committed
860
 *
861 862
 * There are only two requests that we are going to see in actual
 * practise: LM_ST_SHARED and LM_ST_UNLOCKED
David Teigland's avatar
David Teigland committed
863 864
 */

865
static void handle_callback(struct gfs2_glock *gl, unsigned int state,
866
			    unsigned long delay)
David Teigland's avatar
David Teigland committed
867
{
868
	int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
David Teigland's avatar
David Teigland committed
869

870 871 872 873 874 875 876
	set_bit(bit, &gl->gl_flags);
	if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
		gl->gl_demote_state = state;
		gl->gl_demote_time = jiffies;
	} else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
			gl->gl_demote_state != state) {
		gl->gl_demote_state = LM_ST_UNLOCKED;
David Teigland's avatar
David Teigland committed
877 878 879 880
	}
}

/**
881
 * gfs2_glock_wait - wait on a glock acquisition
David Teigland's avatar
David Teigland committed
882 883 884 885 886
 * @gh: the glock holder
 *
 * Returns: 0 on success
 */

887
int gfs2_glock_wait(struct gfs2_holder *gh)
David Teigland's avatar
David Teigland committed
888
{
889
	wait_on_holder(gh);
David Teigland's avatar
David Teigland committed
890 891 892
	return gh->gh_error;
}

893
void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
894 895 896 897
{
	va_list args;

	va_start(args, fmt);
898 899
	if (seq) {
		struct gfs2_glock_iter *gi = seq->private;
900
		vsprintf(gi->string, fmt, args);
901 902 903
		seq_printf(seq, gi->string);
	} else {
		printk(KERN_ERR " ");
904
		vprintk(fmt, args);
905
	}
906 907 908
	va_end(args);
}

David Teigland's avatar
David Teigland committed
909 910 911 912
/**
 * add_to_queue - Add a holder to the wait queue (but look for recursion)
 * @gh: the holder structure to add
 *
913 914 915 916
 * Eventually we should move the recursive locking trap to a
 * debugging option or something like that. This is the fast
 * path and needs to have the minimum number of distractions.
 * 
David Teigland's avatar
David Teigland committed
917 918
 */

919
static inline void add_to_queue(struct gfs2_holder *gh)
920 921
__releases(&gl->gl_spin)
__acquires(&gl->gl_spin)
David Teigland's avatar
David Teigland committed
922 923
{
	struct gfs2_glock *gl = gh->gh_gl;
924 925 926 927
	struct gfs2_sbd *sdp = gl->gl_sbd;
	struct list_head *insert_pt = NULL;
	struct gfs2_holder *gh2;
	int try_lock = 0;
David Teigland's avatar
David Teigland committed
928

929
	BUG_ON(gh->gh_owner_pid == NULL);
930 931
	if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
		BUG();
932

933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950
	if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
		if (test_bit(GLF_LOCK, &gl->gl_flags))
			try_lock = 1;
		if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
			goto fail;
	}

	list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
		if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
		    (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
			goto trap_recursive;
		if (try_lock &&
		    !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
		    !may_grant(gl, gh)) {
fail:
			gh->gh_error = GLR_TRYFAILED;
			gfs2_holder_wake(gh);
			return;
951
		}
952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967
		if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
			continue;
		if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
			insert_pt = &gh2->gh_list;
	}
	if (likely(insert_pt == NULL)) {
		list_add_tail(&gh->gh_list, &gl->gl_holders);
		if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
			goto do_cancel;
		return;
	}
	list_add_tail(&gh->gh_list, insert_pt);
do_cancel:
	gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
	if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
		spin_unlock(&gl->gl_spin);
Steven Whitehouse's avatar
Steven Whitehouse committed
968 969
		if (sdp->sd_lockstruct.ls_ops->lm_cancel)
			sdp->sd_lockstruct.ls_ops->lm_cancel(gl->gl_lock);
970
		spin_lock(&gl->gl_spin);
David Teigland's avatar
David Teigland committed
971
	}
972
	return;
David Teigland's avatar
David Teigland committed
973

974 975 976 977 978 979 980 981 982 983 984
trap_recursive:
	print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
	printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
	printk(KERN_ERR "lock type: %d req lock state : %d\n",
	       gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
	print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
	printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
	printk(KERN_ERR "lock type: %d req lock state : %d\n",
	       gh->gh_gl->gl_name.ln_type, gh->gh_state);
	__dump_glock(NULL, gl);
	BUG();
David Teigland's avatar
David Teigland committed
985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001
}

/**
 * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
 * @gh: the holder structure
 *
 * if (gh->gh_flags & GL_ASYNC), this never returns an error
 *
 * Returns: 0, GLR_TRYFAILED, or errno on failure
 */

int gfs2_glock_nq(struct gfs2_holder *gh)
{
	struct gfs2_glock *gl = gh->gh_gl;
	struct gfs2_sbd *sdp = gl->gl_sbd;
	int error = 0;

1002
	if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
David Teigland's avatar
David Teigland committed
1003 1004 1005 1006
		return -EIO;

	spin_lock(&gl->gl_spin);
	add_to_queue(gh);
1007
	run_queue(gl, 1);
David Teigland's avatar
David Teigland committed
1008 1009
	spin_unlock(&gl->gl_spin);

1010 1011
	if (!(gh->gh_flags & GL_ASYNC))
		error = gfs2_glock_wait(gh);
David Teigland's avatar
David Teigland committed
1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024

	return error;
}

/**
 * gfs2_glock_poll - poll to see if an async request has been completed
 * @gh: the holder
 *
 * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
 */

int gfs2_glock_poll(struct gfs2_holder *gh)
{
1025
	return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
David Teigland's avatar
David Teigland committed
1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036
}

/**
 * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
 * @gh: the glock holder
 *
 */

void gfs2_glock_dq(struct gfs2_holder *gh)
{
	struct gfs2_glock *gl = gh->gh_gl;
1037
	const struct gfs2_glock_operations *glops = gl->gl_ops;
1038
	unsigned delay = 0;
1039
	int fast_path = 0;
David Teigland's avatar
David Teigland committed
1040

1041
	spin_lock(&gl->gl_spin);
David Teigland's avatar
David Teigland committed
1042
	if (gh->gh_flags & GL_NOCACHE)
1043
		handle_callback(gl, LM_ST_UNLOCKED, 0);
David Teigland's avatar
David Teigland committed
1044 1045

	list_del_init(&gh->gh_list);
1046
	if (find_first_holder(gl) == NULL) {
1047
		if (glops->go_unlock) {
1048
			GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1049
			spin_unlock(&gl->gl_spin);
David Teigland's avatar
David Teigland committed
1050
			glops->go_unlock(gh);
1051
			spin_lock(&gl->gl_spin);
1052
			clear_bit(GLF_LOCK, &gl->gl_flags);
1053
		}
1054
		gl->gl_stamp = jiffies;
1055 1056 1057 1058
		if (list_empty(&gl->gl_holders) &&
		    !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
		    !test_bit(GLF_DEMOTE, &gl->gl_flags))
			fast_path = 1;
David Teigland's avatar
David Teigland committed
1059 1060
	}
	spin_unlock(&gl->gl_spin);
1061 1062
	if (likely(fast_path))
		return;
1063 1064 1065 1066 1067 1068 1069

	gfs2_glock_hold(gl);
	if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
	    !test_bit(GLF_DEMOTE, &gl->gl_flags))
		delay = gl->gl_ops->go_min_hold_time;
	if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
		gfs2_glock_put(gl);
David Teigland's avatar
David Teigland committed
1070 1071
}

Abhijith Das's avatar
Abhijith Das committed
1072 1073 1074 1075 1076 1077 1078
void gfs2_glock_dq_wait(struct gfs2_holder *gh)
{
	struct gfs2_glock *gl = gh->gh_gl;
	gfs2_glock_dq(gh);
	wait_on_demote(gl);
}

David Teigland's avatar
David Teigland committed
1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102
/**
 * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
 * @gh: the holder structure
 *
 */

void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
{
	gfs2_glock_dq(gh);
	gfs2_holder_uninit(gh);
}

/**
 * gfs2_glock_nq_num - acquire a glock based on lock number
 * @sdp: the filesystem
 * @number: the lock number
 * @glops: the glock operations for the type of glock
 * @state: the state to acquire the glock in
 * @flags: modifier flags for the aquisition
 * @gh: the struct gfs2_holder
 *
 * Returns: errno
 */

1103
int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1104 1105
		      const struct gfs2_glock_operations *glops,
		      unsigned int state, int flags, struct gfs2_holder *gh)
David Teigland's avatar
David Teigland committed
1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127
{
	struct gfs2_glock *gl;
	int error;

	error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
	if (!error) {
		error = gfs2_glock_nq_init(gl, state, flags, gh);
		gfs2_glock_put(gl);
	}

	return error;
}

/**
 * glock_compare - Compare two struct gfs2_glock structures for sorting
 * @arg_a: the first structure
 * @arg_b: the second structure
 *
 */

static int glock_compare(const void *arg_a, const void *arg_b)
{
1128 1129 1130 1131
	const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
	const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
	const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
	const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
David Teigland's avatar
David Teigland committed
1132 1133

	if (a->ln_number > b->ln_number)
1134 1135 1136
		return 1;
	if (a->ln_number < b->ln_number)
		return -1;
1137
	BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1138
	return 0;
David Teigland's avatar
David Teigland committed
1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186
}

/**
 * nq_m_sync - synchonously acquire more than one glock in deadlock free order
 * @num_gh: the number of structures
 * @ghs: an array of struct gfs2_holder structures
 *
 * Returns: 0 on success (all glocks acquired),
 *          errno on failure (no glocks acquired)
 */

static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
		     struct gfs2_holder **p)
{
	unsigned int x;
	int error = 0;

	for (x = 0; x < num_gh; x++)
		p[x] = &ghs[x];

	sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);

	for (x = 0; x < num_gh; x++) {
		p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);

		error = gfs2_glock_nq(p[x]);
		if (error) {
			while (x--)
				gfs2_glock_dq(p[x]);
			break;
		}
	}

	return error;
}

/**
 * gfs2_glock_nq_m - acquire multiple glocks
 * @num_gh: the number of structures
 * @ghs: an array of struct gfs2_holder structures
 *
 *
 * Returns: 0 on success (all glocks acquired),
 *          errno on failure (no glocks acquired)
 */

int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
{
1187 1188
	struct gfs2_holder *tmp[4];
	struct gfs2_holder **pph = tmp;
David Teigland's avatar
David Teigland committed
1189 1190
	int error = 0;

1191 1192
	switch(num_gh) {
	case 0:
David Teigland's avatar
David Teigland committed
1193
		return 0;
1194
	case 1:
David Teigland's avatar
David Teigland committed
1195 1196
		ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
		return gfs2_glock_nq(ghs);
1197 1198
	default:
		if (num_gh <= 4)
David Teigland's avatar
David Teigland committed
1199
			break;
1200 1201 1202
		pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
		if (!pph)
			return -ENOMEM;
David Teigland's avatar
David Teigland committed
1203 1204
	}

1205
	error = nq_m_sync(num_gh, ghs, pph);
David Teigland's avatar
David Teigland committed
1206

1207 1208
	if (pph != tmp)
		kfree(pph);
David Teigland's avatar
David Teigland committed
1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242

	return error;
}

/**
 * gfs2_glock_dq_m - release multiple glocks
 * @num_gh: the number of structures
 * @ghs: an array of struct gfs2_holder structures
 *
 */

void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
{
	unsigned int x;

	for (x = 0; x < num_gh; x++)
		gfs2_glock_dq(&ghs[x]);
}

/**
 * gfs2_glock_dq_uninit_m - release multiple glocks
 * @num_gh: the number of structures
 * @ghs: an array of struct gfs2_holder structures
 *
 */

void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
{
	unsigned int x;

	for (x = 0; x < num_gh; x++)
		gfs2_glock_dq_uninit(&ghs[x]);
}

1243 1244 1245
static int gfs2_lm_hold_lvb(struct gfs2_sbd *sdp, void *lock, char **lvbp)
{
	int error = -EIO;
Steven Whitehouse's avatar
Steven Whitehouse committed
1246 1247
	if (!sdp->sd_lockstruct.ls_ops->lm_hold_lvb)
		return 0;
1248 1249 1250 1251 1252
	if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
		error = sdp->sd_lockstruct.ls_ops->lm_hold_lvb(lock, lvbp);
	return error;
}