locks.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  linux/fs/locks.c
   4 *
   5 * We implement four types of file locks: BSD locks, posix locks, open
   6 * file description locks, and leases.  For details about BSD locks,
   7 * see the flock(2) man page; for details about the other three, see
   8 * fcntl(2).
   9 *
  10 *
  11 * Locking conflicts and dependencies:
  12 * If multiple threads attempt to lock the same byte (or flock the same file)
  13 * only one can be granted the lock, and other must wait their turn.
  14 * The first lock has been "applied" or "granted", the others are "waiting"
  15 * and are "blocked" by the "applied" lock..
  16 *
  17 * Waiting and applied locks are all kept in trees whose properties are:
  18 *
  19 *	- the root of a tree may be an applied or waiting lock.
  20 *	- every other node in the tree is a waiting lock that
  21 *	  conflicts with every ancestor of that node.
  22 *
  23 * Every such tree begins life as a waiting singleton which obviously
  24 * satisfies the above properties.
  25 *
  26 * The only ways we modify trees preserve these properties:
  27 *
  28 *	1. We may add a new leaf node, but only after first verifying that it
  29 *	   conflicts with all of its ancestors.
  30 *	2. We may remove the root of a tree, creating a new singleton
  31 *	   tree from the root and N new trees rooted in the immediate
  32 *	   children.
  33 *	3. If the root of a tree is not currently an applied lock, we may
  34 *	   apply it (if possible).
  35 *	4. We may upgrade the root of the tree (either extend its range,
  36 *	   or upgrade its entire range from read to write).
  37 *
  38 * When an applied lock is modified in a way that reduces or downgrades any
  39 * part of its range, we remove all its children (2 above).  This particularly
  40 * happens when a lock is unlocked.
  41 *
  42 * For each of those child trees we "wake up" the thread which is
  43 * waiting for the lock so it can continue handling as follows: if the
  44 * root of the tree applies, we do so (3).  If it doesn't, it must
  45 * conflict with some applied lock.  We remove (wake up) all of its children
  46 * (2), and add it is a new leaf to the tree rooted in the applied
  47 * lock (1).  We then repeat the process recursively with those
  48 * children.
  49 *
  50 */
  51#include <linux/capability.h>
  52#include <linux/file.h>
  53#include <linux/fdtable.h>
  54#include <linux/filelock.h>
  55#include <linux/fs.h>
  56#include <linux/init.h>
  57#include <linux/security.h>
  58#include <linux/slab.h>
  59#include <linux/syscalls.h>
  60#include <linux/time.h>
  61#include <linux/rcupdate.h>
  62#include <linux/pid_namespace.h>
  63#include <linux/hashtable.h>
  64#include <linux/percpu.h>
  65#include <linux/sysctl.h>
  66
  67#define CREATE_TRACE_POINTS
  68#include <trace/events/filelock.h>
  69
  70#include <linux/uaccess.h>
  71
  72static struct file_lock *file_lock(struct file_lock_core *flc)
  73{
  74	return container_of(flc, struct file_lock, c);
  75}
  76
  77static struct file_lease *file_lease(struct file_lock_core *flc)
  78{
  79	return container_of(flc, struct file_lease, c);
  80}
  81
  82static bool lease_breaking(struct file_lease *fl)
  83{
  84	return fl->c.flc_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
  85}
  86
  87static int target_leasetype(struct file_lease *fl)
  88{
  89	if (fl->c.flc_flags & FL_UNLOCK_PENDING)
  90		return F_UNLCK;
  91	if (fl->c.flc_flags & FL_DOWNGRADE_PENDING)
  92		return F_RDLCK;
  93	return fl->c.flc_type;
  94}
  95
  96static int leases_enable = 1;
  97static int lease_break_time = 45;
  98
  99#ifdef CONFIG_SYSCTL
 100static const struct ctl_table locks_sysctls[] = {
 101	{
 102		.procname	= "leases-enable",
 103		.data		= &leases_enable,
 104		.maxlen		= sizeof(int),
 105		.mode		= 0644,
 106		.proc_handler	= proc_dointvec,
 107	},
 108#ifdef CONFIG_MMU
 109	{
 110		.procname	= "lease-break-time",
 111		.data		= &lease_break_time,
 112		.maxlen		= sizeof(int),
 113		.mode		= 0644,
 114		.proc_handler	= proc_dointvec,
 115	},
 116#endif /* CONFIG_MMU */
 117};
 118
 119static int __init init_fs_locks_sysctls(void)
 120{
 121	register_sysctl_init("fs", locks_sysctls);
 122	return 0;
 123}
 124early_initcall(init_fs_locks_sysctls);
 125#endif /* CONFIG_SYSCTL */
 126
 127/*
 128 * The global file_lock_list is only used for displaying /proc/locks, so we
 129 * keep a list on each CPU, with each list protected by its own spinlock.
 130 * Global serialization is done using file_rwsem.
 131 *
 132 * Note that alterations to the list also require that the relevant flc_lock is
 133 * held.
 134 */
 135struct file_lock_list_struct {
 136	spinlock_t		lock;
 137	struct hlist_head	hlist;
 138};
 139static DEFINE_PER_CPU(struct file_lock_list_struct, file_lock_list);
 140DEFINE_STATIC_PERCPU_RWSEM(file_rwsem);
 141
 142
 143/*
 144 * The blocked_hash is used to find POSIX lock loops for deadlock detection.
 145 * It is protected by blocked_lock_lock.
 146 *
 147 * We hash locks by lockowner in order to optimize searching for the lock a
 148 * particular lockowner is waiting on.
 149 *
 150 * FIXME: make this value scale via some heuristic? We generally will want more
 151 * buckets when we have more lockowners holding locks, but that's a little
 152 * difficult to determine without knowing what the workload will look like.
 153 */
 154#define BLOCKED_HASH_BITS	7
 155static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
 156
 157/*
 158 * This lock protects the blocked_hash. Generally, if you're accessing it, you
 159 * want to be holding this lock.
 160 *
 161 * In addition, it also protects the fl->fl_blocked_requests list, and the
 162 * fl->fl_blocker pointer for file_lock structures that are acting as lock
 163 * requests (in contrast to those that are acting as records of acquired locks).
 164 *
 165 * Note that when we acquire this lock in order to change the above fields,
 166 * we often hold the flc_lock as well. In certain cases, when reading the fields
 167 * protected by this lock, we can skip acquiring it iff we already hold the
 168 * flc_lock.
 169 */
 170static DEFINE_SPINLOCK(blocked_lock_lock);
 171
 172static struct kmem_cache *flctx_cache __ro_after_init;
 173static struct kmem_cache *filelock_cache __ro_after_init;
 174static struct kmem_cache *filelease_cache __ro_after_init;
 175
 176static struct file_lock_context *
 177locks_get_lock_context(struct inode *inode, int type)
 178{
 179	struct file_lock_context *ctx;
 180
 181	/* paired with cmpxchg() below */
 182	ctx = locks_inode_context(inode);
 183	if (likely(ctx) || type == F_UNLCK)
 184		goto out;
 185
 186	ctx = kmem_cache_alloc(flctx_cache, GFP_KERNEL);
 187	if (!ctx)
 188		goto out;
 189
 190	spin_lock_init(&ctx->flc_lock);
 191	INIT_LIST_HEAD(&ctx->flc_flock);
 192	INIT_LIST_HEAD(&ctx->flc_posix);
 193	INIT_LIST_HEAD(&ctx->flc_lease);
 194
 195	/*
 196	 * Assign the pointer if it's not already assigned. If it is, then
 197	 * free the context we just allocated.
 198	 */
 199	if (cmpxchg(&inode->i_flctx, NULL, ctx)) {
 200		kmem_cache_free(flctx_cache, ctx);
 201		ctx = locks_inode_context(inode);
 202	}
 203out:
 204	trace_locks_get_lock_context(inode, type, ctx);
 205	return ctx;
 206}
 207
 208static void
 209locks_dump_ctx_list(struct list_head *list, char *list_type)
 210{
 211	struct file_lock_core *flc;
 212
 213	list_for_each_entry(flc, list, flc_list)
 214		pr_warn("%s: fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n",
 215			list_type, flc->flc_owner, flc->flc_flags,
 216			flc->flc_type, flc->flc_pid);
 217}
 218
 219static void
 220locks_check_ctx_lists(struct inode *inode)
 221{
 222	struct file_lock_context *ctx = inode->i_flctx;
 223
 224	if (unlikely(!list_empty(&ctx->flc_flock) ||
 225		     !list_empty(&ctx->flc_posix) ||
 226		     !list_empty(&ctx->flc_lease))) {
 227		pr_warn("Leaked locks on dev=0x%x:0x%x ino=0x%lx:\n",
 228			MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev),
 229			inode->i_ino);
 230		locks_dump_ctx_list(&ctx->flc_flock, "FLOCK");
 231		locks_dump_ctx_list(&ctx->flc_posix, "POSIX");
 232		locks_dump_ctx_list(&ctx->flc_lease, "LEASE");
 233	}
 234}
 235
 236static void
 237locks_check_ctx_file_list(struct file *filp, struct list_head *list, char *list_type)
 238{
 239	struct file_lock_core *flc;
 240	struct inode *inode = file_inode(filp);
 241
 242	list_for_each_entry(flc, list, flc_list)
 243		if (flc->flc_file == filp)
 244			pr_warn("Leaked %s lock on dev=0x%x:0x%x ino=0x%lx "
 245				" fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n",
 246				list_type, MAJOR(inode->i_sb->s_dev),
 247				MINOR(inode->i_sb->s_dev), inode->i_ino,
 248				flc->flc_owner, flc->flc_flags,
 249				flc->flc_type, flc->flc_pid);
 250}
 251
 252void
 253locks_free_lock_context(struct inode *inode)
 254{
 255	struct file_lock_context *ctx = locks_inode_context(inode);
 256
 257	if (unlikely(ctx)) {
 258		locks_check_ctx_lists(inode);
 259		kmem_cache_free(flctx_cache, ctx);
 260	}
 261}
 262
 263static void locks_init_lock_heads(struct file_lock_core *flc)
 264{
 265	INIT_HLIST_NODE(&flc->flc_link);
 266	INIT_LIST_HEAD(&flc->flc_list);
 267	INIT_LIST_HEAD(&flc->flc_blocked_requests);
 268	INIT_LIST_HEAD(&flc->flc_blocked_member);
 269	init_waitqueue_head(&flc->flc_wait);
 270}
 271
 272/* Allocate an empty lock structure. */
 273struct file_lock *locks_alloc_lock(void)
 274{
 275	struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
 276
 277	if (fl)
 278		locks_init_lock_heads(&fl->c);
 279
 280	return fl;
 281}
 282EXPORT_SYMBOL_GPL(locks_alloc_lock);
 283
 284/* Allocate an empty lock structure. */
 285struct file_lease *locks_alloc_lease(void)
 286{
 287	struct file_lease *fl = kmem_cache_zalloc(filelease_cache, GFP_KERNEL);
 288
 289	if (fl)
 290		locks_init_lock_heads(&fl->c);
 291
 292	return fl;
 293}
 294EXPORT_SYMBOL_GPL(locks_alloc_lease);
 295
 296void locks_release_private(struct file_lock *fl)
 297{
 298	struct file_lock_core *flc = &fl->c;
 299
 300	BUG_ON(waitqueue_active(&flc->flc_wait));
 301	BUG_ON(!list_empty(&flc->flc_list));
 302	BUG_ON(!list_empty(&flc->flc_blocked_requests));
 303	BUG_ON(!list_empty(&flc->flc_blocked_member));
 304	BUG_ON(!hlist_unhashed(&flc->flc_link));
 305
 306	if (fl->fl_ops) {
 307		if (fl->fl_ops->fl_release_private)
 308			fl->fl_ops->fl_release_private(fl);
 309		fl->fl_ops = NULL;
 310	}
 311
 312	if (fl->fl_lmops) {
 313		if (fl->fl_lmops->lm_put_owner) {
 314			fl->fl_lmops->lm_put_owner(flc->flc_owner);
 315			flc->flc_owner = NULL;
 316		}
 317		fl->fl_lmops = NULL;
 318	}
 319}
 320EXPORT_SYMBOL_GPL(locks_release_private);
 321
 322/**
 323 * locks_owner_has_blockers - Check for blocking lock requests
 324 * @flctx: file lock context
 325 * @owner: lock owner
 326 *
 327 * Return values:
 328 *   %true: @owner has at least one blocker
 329 *   %false: @owner has no blockers
 330 */
 331bool locks_owner_has_blockers(struct file_lock_context *flctx, fl_owner_t owner)
 332{
 333	struct file_lock_core *flc;
 334
 335	spin_lock(&flctx->flc_lock);
 336	list_for_each_entry(flc, &flctx->flc_posix, flc_list) {
 337		if (flc->flc_owner != owner)
 338			continue;
 339		if (!list_empty(&flc->flc_blocked_requests)) {
 340			spin_unlock(&flctx->flc_lock);
 341			return true;
 342		}
 343	}
 344	spin_unlock(&flctx->flc_lock);
 345	return false;
 346}
 347EXPORT_SYMBOL_GPL(locks_owner_has_blockers);
 348
 349/* Free a lock which is not in use. */
 350void locks_free_lock(struct file_lock *fl)
 351{
 352	locks_release_private(fl);
 353	kmem_cache_free(filelock_cache, fl);
 354}
 355EXPORT_SYMBOL(locks_free_lock);
 356
 357/* Free a lease which is not in use. */
 358void locks_free_lease(struct file_lease *fl)
 359{
 360	kmem_cache_free(filelease_cache, fl);
 361}
 362EXPORT_SYMBOL(locks_free_lease);
 363
 364static void
 365locks_dispose_list(struct list_head *dispose)
 366{
 367	struct file_lock_core *flc;
 368
 369	while (!list_empty(dispose)) {
 370		flc = list_first_entry(dispose, struct file_lock_core, flc_list);
 371		list_del_init(&flc->flc_list);
 372		locks_free_lock(file_lock(flc));
 373	}
 374}
 375
 376static void
 377lease_dispose_list(struct list_head *dispose)
 378{
 379	struct file_lock_core *flc;
 380
 381	while (!list_empty(dispose)) {
 382		flc = list_first_entry(dispose, struct file_lock_core, flc_list);
 383		list_del_init(&flc->flc_list);
 384		locks_free_lease(file_lease(flc));
 385	}
 386}
 387
 388void locks_init_lock(struct file_lock *fl)
 389{
 390	memset(fl, 0, sizeof(struct file_lock));
 391	locks_init_lock_heads(&fl->c);
 392}
 393EXPORT_SYMBOL(locks_init_lock);
 394
 395void locks_init_lease(struct file_lease *fl)
 396{
 397	memset(fl, 0, sizeof(*fl));
 398	locks_init_lock_heads(&fl->c);
 399}
 400EXPORT_SYMBOL(locks_init_lease);
 401
 402/*
 403 * Initialize a new lock from an existing file_lock structure.
 404 */
 405void locks_copy_conflock(struct file_lock *new, struct file_lock *fl)
 406{
 407	new->c.flc_owner = fl->c.flc_owner;
 408	new->c.flc_pid = fl->c.flc_pid;
 409	new->c.flc_file = NULL;
 410	new->c.flc_flags = fl->c.flc_flags;
 411	new->c.flc_type = fl->c.flc_type;
 412	new->fl_start = fl->fl_start;
 413	new->fl_end = fl->fl_end;
 414	new->fl_lmops = fl->fl_lmops;
 415	new->fl_ops = NULL;
 416
 417	if (fl->fl_lmops) {
 418		if (fl->fl_lmops->lm_get_owner)
 419			fl->fl_lmops->lm_get_owner(fl->c.flc_owner);
 420	}
 421}
 422EXPORT_SYMBOL(locks_copy_conflock);
 423
 424void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 425{
 426	/* "new" must be a freshly-initialized lock */
 427	WARN_ON_ONCE(new->fl_ops);
 428
 429	locks_copy_conflock(new, fl);
 430
 431	new->c.flc_file = fl->c.flc_file;
 432	new->fl_ops = fl->fl_ops;
 433
 434	if (fl->fl_ops) {
 435		if (fl->fl_ops->fl_copy_lock)
 436			fl->fl_ops->fl_copy_lock(new, fl);
 437	}
 438}
 439EXPORT_SYMBOL(locks_copy_lock);
 440
 441static void locks_move_blocks(struct file_lock *new, struct file_lock *fl)
 442{
 443	struct file_lock *f;
 444
 445	/*
 446	 * As ctx->flc_lock is held, new requests cannot be added to
 447	 * ->flc_blocked_requests, so we don't need a lock to check if it
 448	 * is empty.
 449	 */
 450	if (list_empty(&fl->c.flc_blocked_requests))
 451		return;
 452	spin_lock(&blocked_lock_lock);
 453	list_splice_init(&fl->c.flc_blocked_requests,
 454			 &new->c.flc_blocked_requests);
 455	list_for_each_entry(f, &new->c.flc_blocked_requests,
 456			    c.flc_blocked_member)
 457		f->c.flc_blocker = &new->c;
 458	spin_unlock(&blocked_lock_lock);
 459}
 460
 461static inline int flock_translate_cmd(int cmd) {
 462	switch (cmd) {
 463	case LOCK_SH:
 464		return F_RDLCK;
 465	case LOCK_EX:
 466		return F_WRLCK;
 467	case LOCK_UN:
 468		return F_UNLCK;
 469	}
 470	return -EINVAL;
 471}
 472
 473/* Fill in a file_lock structure with an appropriate FLOCK lock. */
 474static void flock_make_lock(struct file *filp, struct file_lock *fl, int type)
 475{
 476	locks_init_lock(fl);
 477
 478	fl->c.flc_file = filp;
 479	fl->c.flc_owner = filp;
 480	fl->c.flc_pid = current->tgid;
 481	fl->c.flc_flags = FL_FLOCK;
 482	fl->c.flc_type = type;
 483	fl->fl_end = OFFSET_MAX;
 484}
 485
 486static int assign_type(struct file_lock_core *flc, int type)
 487{
 488	switch (type) {
 489	case F_RDLCK:
 490	case F_WRLCK:
 491	case F_UNLCK:
 492		flc->flc_type = type;
 493		break;
 494	default:
 495		return -EINVAL;
 496	}
 497	return 0;
 498}
 499
 500static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
 501				 struct flock64 *l)
 502{
 503	switch (l->l_whence) {
 504	case SEEK_SET:
 505		fl->fl_start = 0;
 506		break;
 507	case SEEK_CUR:
 508		fl->fl_start = filp->f_pos;
 509		break;
 510	case SEEK_END:
 511		fl->fl_start = i_size_read(file_inode(filp));
 512		break;
 513	default:
 514		return -EINVAL;
 515	}
 516	if (l->l_start > OFFSET_MAX - fl->fl_start)
 517		return -EOVERFLOW;
 518	fl->fl_start += l->l_start;
 519	if (fl->fl_start < 0)
 520		return -EINVAL;
 521
 522	/* POSIX-1996 leaves the case l->l_len < 0 undefined;
 523	   POSIX-2001 defines it. */
 524	if (l->l_len > 0) {
 525		if (l->l_len - 1 > OFFSET_MAX - fl->fl_start)
 526			return -EOVERFLOW;
 527		fl->fl_end = fl->fl_start + (l->l_len - 1);
 528
 529	} else if (l->l_len < 0) {
 530		if (fl->fl_start + l->l_len < 0)
 531			return -EINVAL;
 532		fl->fl_end = fl->fl_start - 1;
 533		fl->fl_start += l->l_len;
 534	} else
 535		fl->fl_end = OFFSET_MAX;
 536
 537	fl->c.flc_owner = current->files;
 538	fl->c.flc_pid = current->tgid;
 539	fl->c.flc_file = filp;
 540	fl->c.flc_flags = FL_POSIX;
 541	fl->fl_ops = NULL;
 542	fl->fl_lmops = NULL;
 543
 544	return assign_type(&fl->c, l->l_type);
 545}
 546
 547/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
 548 * style lock.
 549 */
 550static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
 551			       struct flock *l)
 552{
 553	struct flock64 ll = {
 554		.l_type = l->l_type,
 555		.l_whence = l->l_whence,
 556		.l_start = l->l_start,
 557		.l_len = l->l_len,
 558	};
 559
 560	return flock64_to_posix_lock(filp, fl, &ll);
 561}
 562
 563/* default lease lock manager operations */
 564static bool
 565lease_break_callback(struct file_lease *fl)
 566{
 567	kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
 568	return false;
 569}
 570
 571static void
 572lease_setup(struct file_lease *fl, void **priv)
 573{
 574	struct file *filp = fl->c.flc_file;
 575	struct fasync_struct *fa = *priv;
 576
 577	/*
 578	 * fasync_insert_entry() returns the old entry if any. If there was no
 579	 * old entry, then it used "priv" and inserted it into the fasync list.
 580	 * Clear the pointer to indicate that it shouldn't be freed.
 581	 */
 582	if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa))
 583		*priv = NULL;
 584
 585	__f_setown(filp, task_pid(current), PIDTYPE_TGID, 0);
 586}
 587
 588/**
 589 * lease_open_conflict - see if the given file points to an inode that has
 590 *			 an existing open that would conflict with the
 591 *			 desired lease.
 592 * @filp:	file to check
 593 * @arg:	type of lease that we're trying to acquire
 594 *
 595 * Check to see if there's an existing open fd on this file that would
 596 * conflict with the lease we're trying to set.
 597 */
 598static int
 599lease_open_conflict(struct file *filp, const int arg)
 600{
 601	struct inode *inode = file_inode(filp);
 602	int self_wcount = 0, self_rcount = 0;
 603
 604	if (arg == F_RDLCK)
 605		return inode_is_open_for_write(inode) ? -EAGAIN : 0;
 606	else if (arg != F_WRLCK)
 607		return 0;
 608
 609	/*
 610	 * Make sure that only read/write count is from lease requestor.
 611	 * Note that this will result in denying write leases when i_writecount
 612	 * is negative, which is what we want.  (We shouldn't grant write leases
 613	 * on files open for execution.)
 614	 */
 615	if (filp->f_mode & FMODE_WRITE)
 616		self_wcount = 1;
 617	else if (filp->f_mode & FMODE_READ)
 618		self_rcount = 1;
 619
 620	if (atomic_read(&inode->i_writecount) != self_wcount ||
 621	    atomic_read(&inode->i_readcount) != self_rcount)
 622		return -EAGAIN;
 623
 624	return 0;
 625}
 626
 627static const struct lease_manager_operations lease_manager_ops = {
 628	.lm_break = lease_break_callback,
 629	.lm_change = lease_modify,
 630	.lm_setup = lease_setup,
 631	.lm_open_conflict = lease_open_conflict,
 632};
 633
 634/*
 635 * Initialize a lease, use the default lock manager operations
 636 */
 637static int lease_init(struct file *filp, unsigned int flags, int type, struct file_lease *fl)
 638{
 639	if (assign_type(&fl->c, type) != 0)
 640		return -EINVAL;
 641
 642	fl->c.flc_owner = filp;
 643	fl->c.flc_pid = current->tgid;
 644
 645	fl->c.flc_file = filp;
 646	fl->c.flc_flags = flags;
 647	fl->fl_lmops = &lease_manager_ops;
 648	return 0;
 649}
 650
 651/* Allocate a file_lock initialised to this type of lease */
 652static struct file_lease *lease_alloc(struct file *filp, unsigned int flags, int type)
 653{
 654	struct file_lease *fl = locks_alloc_lease();
 655	int error = -ENOMEM;
 656
 657	if (fl == NULL)
 658		return ERR_PTR(error);
 659
 660	error = lease_init(filp, flags, type, fl);
 661	if (error) {
 662		locks_free_lease(fl);
 663		return ERR_PTR(error);
 664	}
 665	return fl;
 666}
 667
 668/* Check if two locks overlap each other.
 669 */
 670static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
 671{
 672	return ((fl1->fl_end >= fl2->fl_start) &&
 673		(fl2->fl_end >= fl1->fl_start));
 674}
 675
 676/*
 677 * Check whether two locks have the same owner.
 678 */
 679static int posix_same_owner(struct file_lock_core *fl1, struct file_lock_core *fl2)
 680{
 681	return fl1->flc_owner == fl2->flc_owner;
 682}
 683
 684/* Must be called with the flc_lock held! */
 685static void locks_insert_global_locks(struct file_lock_core *flc)
 686{
 687	struct file_lock_list_struct *fll = this_cpu_ptr(&file_lock_list);
 688
 689	percpu_rwsem_assert_held(&file_rwsem);
 690
 691	spin_lock(&fll->lock);
 692	flc->flc_link_cpu = smp_processor_id();
 693	hlist_add_head(&flc->flc_link, &fll->hlist);
 694	spin_unlock(&fll->lock);
 695}
 696
 697/* Must be called with the flc_lock held! */
 698static void locks_delete_global_locks(struct file_lock_core *flc)
 699{
 700	struct file_lock_list_struct *fll;
 701
 702	percpu_rwsem_assert_held(&file_rwsem);
 703
 704	/*
 705	 * Avoid taking lock if already unhashed. This is safe since this check
 706	 * is done while holding the flc_lock, and new insertions into the list
 707	 * also require that it be held.
 708	 */
 709	if (hlist_unhashed(&flc->flc_link))
 710		return;
 711
 712	fll = per_cpu_ptr(&file_lock_list, flc->flc_link_cpu);
 713	spin_lock(&fll->lock);
 714	hlist_del_init(&flc->flc_link);
 715	spin_unlock(&fll->lock);
 716}
 717
 718static unsigned long
 719posix_owner_key(struct file_lock_core *flc)
 720{
 721	return (unsigned long) flc->flc_owner;
 722}
 723
 724static void locks_insert_global_blocked(struct file_lock_core *waiter)
 725{
 726	lockdep_assert_held(&blocked_lock_lock);
 727
 728	hash_add(blocked_hash, &waiter->flc_link, posix_owner_key(waiter));
 729}
 730
 731static void locks_delete_global_blocked(struct file_lock_core *waiter)
 732{
 733	lockdep_assert_held(&blocked_lock_lock);
 734
 735	hash_del(&waiter->flc_link);
 736}
 737
 738/* Remove waiter from blocker's block list.
 739 * When blocker ends up pointing to itself then the list is empty.
 740 *
 741 * Must be called with blocked_lock_lock held.
 742 */
 743static void __locks_unlink_block(struct file_lock_core *waiter)
 744{
 745	locks_delete_global_blocked(waiter);
 746	list_del_init(&waiter->flc_blocked_member);
 747}
 748
 749static void __locks_wake_up_blocks(struct file_lock_core *blocker)
 750{
 751	while (!list_empty(&blocker->flc_blocked_requests)) {
 752		struct file_lock_core *waiter;
 753		struct file_lock *fl;
 754
 755		waiter = list_first_entry(&blocker->flc_blocked_requests,
 756					  struct file_lock_core, flc_blocked_member);
 757
 758		fl = file_lock(waiter);
 759		__locks_unlink_block(waiter);
 760		if ((waiter->flc_flags & (FL_POSIX | FL_FLOCK)) &&
 761		    fl->fl_lmops && fl->fl_lmops->lm_notify)
 762			fl->fl_lmops->lm_notify(fl);
 763		else
 764			locks_wake_up_waiter(waiter);
 765
 766		/*
 767		 * The setting of flc_blocker to NULL marks the "done"
 768		 * point in deleting a block. Paired with acquire at the top
 769		 * of locks_delete_block().
 770		 */
 771		smp_store_release(&waiter->flc_blocker, NULL);
 772	}
 773}
 774
 775static int __locks_delete_block(struct file_lock_core *waiter)
 776{
 777	int status = -ENOENT;
 778
 779	/*
 780	 * If fl_blocker is NULL, it won't be set again as this thread "owns"
 781	 * the lock and is the only one that might try to claim the lock.
 782	 *
 783	 * We use acquire/release to manage fl_blocker so that we can
 784	 * optimize away taking the blocked_lock_lock in many cases.
 785	 *
 786	 * The smp_load_acquire guarantees two things:
 787	 *
 788	 * 1/ that fl_blocked_requests can be tested locklessly. If something
 789	 * was recently added to that list it must have been in a locked region
 790	 * *before* the locked region when fl_blocker was set to NULL.
 791	 *
 792	 * 2/ that no other thread is accessing 'waiter', so it is safe to free
 793	 * it.  __locks_wake_up_blocks is careful not to touch waiter after
 794	 * fl_blocker is released.
 795	 *
 796	 * If a lockless check of fl_blocker shows it to be NULL, we know that
 797	 * no new locks can be inserted into its fl_blocked_requests list, and
 798	 * can avoid doing anything further if the list is empty.
 799	 */
 800	if (!smp_load_acquire(&waiter->flc_blocker) &&
 801	    list_empty(&waiter->flc_blocked_requests))
 802		return status;
 803
 804	spin_lock(&blocked_lock_lock);
 805	if (waiter->flc_blocker)
 806		status = 0;
 807	__locks_wake_up_blocks(waiter);
 808	__locks_unlink_block(waiter);
 809
 810	/*
 811	 * The setting of fl_blocker to NULL marks the "done" point in deleting
 812	 * a block. Paired with acquire at the top of this function.
 813	 */
 814	smp_store_release(&waiter->flc_blocker, NULL);
 815	spin_unlock(&blocked_lock_lock);
 816	return status;
 817}
 818
 819/**
 820 *	locks_delete_block - stop waiting for a file lock
 821 *	@waiter: the lock which was waiting
 822 *
 823 *	lockd/nfsd need to disconnect the lock while working on it.
 824 */
 825int locks_delete_block(struct file_lock *waiter)
 826{
 827	return __locks_delete_block(&waiter->c);
 828}
 829EXPORT_SYMBOL(locks_delete_block);
 830
 831/* Insert waiter into blocker's block list.
 832 * We use a circular list so that processes can be easily woken up in
 833 * the order they blocked. The documentation doesn't require this but
 834 * it seems like the reasonable thing to do.
 835 *
 836 * Must be called with both the flc_lock and blocked_lock_lock held. The
 837 * fl_blocked_requests list itself is protected by the blocked_lock_lock,
 838 * but by ensuring that the flc_lock is also held on insertions we can avoid
 839 * taking the blocked_lock_lock in some cases when we see that the
 840 * fl_blocked_requests list is empty.
 841 *
 842 * Rather than just adding to the list, we check for conflicts with any existing
 843 * waiters, and add beneath any waiter that blocks the new waiter.
 844 * Thus wakeups don't happen until needed.
 845 */
 846static void __locks_insert_block(struct file_lock_core *blocker,
 847				 struct file_lock_core *waiter,
 848				 bool conflict(struct file_lock_core *,
 849					       struct file_lock_core *))
 850{
 851	struct file_lock_core *flc;
 852
 853	BUG_ON(!list_empty(&waiter->flc_blocked_member));
 854new_blocker:
 855	list_for_each_entry(flc, &blocker->flc_blocked_requests, flc_blocked_member)
 856		if (conflict(flc, waiter)) {
 857			blocker =  flc;
 858			goto new_blocker;
 859		}
 860	waiter->flc_blocker = blocker;
 861	list_add_tail(&waiter->flc_blocked_member,
 862		      &blocker->flc_blocked_requests);
 863
 864	if ((blocker->flc_flags & (FL_POSIX|FL_OFDLCK)) == FL_POSIX)
 865		locks_insert_global_blocked(waiter);
 866
 867	/* The requests in waiter->flc_blocked are known to conflict with
 868	 * waiter, but might not conflict with blocker, or the requests
 869	 * and lock which block it.  So they all need to be woken.
 870	 */
 871	__locks_wake_up_blocks(waiter);
 872}
 873
 874/* Must be called with flc_lock held. */
 875static void locks_insert_block(struct file_lock_core *blocker,
 876			       struct file_lock_core *waiter,
 877			       bool conflict(struct file_lock_core *,
 878					     struct file_lock_core *))
 879{
 880	spin_lock(&blocked_lock_lock);
 881	__locks_insert_block(blocker, waiter, conflict);
 882	spin_unlock(&blocked_lock_lock);
 883}
 884
 885/*
 886 * Wake up processes blocked waiting for blocker.
 887 *
 888 * Must be called with the inode->flc_lock held!
 889 */
 890static void locks_wake_up_blocks(struct file_lock_core *blocker)
 891{
 892	/*
 893	 * Avoid taking global lock if list is empty. This is safe since new
 894	 * blocked requests are only added to the list under the flc_lock, and
 895	 * the flc_lock is always held here. Note that removal from the
 896	 * fl_blocked_requests list does not require the flc_lock, so we must
 897	 * recheck list_empty() after acquiring the blocked_lock_lock.
 898	 */
 899	if (list_empty(&blocker->flc_blocked_requests))
 900		return;
 901
 902	spin_lock(&blocked_lock_lock);
 903	__locks_wake_up_blocks(blocker);
 904	spin_unlock(&blocked_lock_lock);
 905}
 906
 907static void
 908locks_insert_lock_ctx(struct file_lock_core *fl, struct list_head *before)
 909{
 910	list_add_tail(&fl->flc_list, before);
 911	locks_insert_global_locks(fl);
 912}
 913
 914static void
 915locks_unlink_lock_ctx(struct file_lock_core *fl)
 916{
 917	locks_delete_global_locks(fl);
 918	list_del_init(&fl->flc_list);
 919	locks_wake_up_blocks(fl);
 920}
 921
 922static void
 923locks_delete_lock_ctx(struct file_lock_core *fl, struct list_head *dispose)
 924{
 925	locks_unlink_lock_ctx(fl);
 926	if (dispose)
 927		list_add(&fl->flc_list, dispose);
 928	else
 929		locks_free_lock(file_lock(fl));
 930}
 931
 932/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
 933 * checks for shared/exclusive status of overlapping locks.
 934 */
 935static bool locks_conflict(struct file_lock_core *caller_flc,
 936			   struct file_lock_core *sys_flc)
 937{
 938	if (sys_flc->flc_type == F_WRLCK)
 939		return true;
 940	if (caller_flc->flc_type == F_WRLCK)
 941		return true;
 942	return false;
 943}
 944
 945/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
 946 * checking before calling the locks_conflict().
 947 */
 948static bool posix_locks_conflict(struct file_lock_core *caller_flc,
 949				 struct file_lock_core *sys_flc)
 950{
 951	struct file_lock *caller_fl = file_lock(caller_flc);
 952	struct file_lock *sys_fl = file_lock(sys_flc);
 953
 954	/* POSIX locks owned by the same process do not conflict with
 955	 * each other.
 956	 */
 957	if (posix_same_owner(caller_flc, sys_flc))
 958		return false;
 959
 960	/* Check whether they overlap */
 961	if (!locks_overlap(caller_fl, sys_fl))
 962		return false;
 963
 964	return locks_conflict(caller_flc, sys_flc);
 965}
 966
 967/* Determine if lock sys_fl blocks lock caller_fl. Used on xx_GETLK
 968 * path so checks for additional GETLK-specific things like F_UNLCK.
 969 */
 970static bool posix_test_locks_conflict(struct file_lock *caller_fl,
 971				      struct file_lock *sys_fl)
 972{
 973	struct file_lock_core *caller = &caller_fl->c;
 974	struct file_lock_core *sys = &sys_fl->c;
 975
 976	/* F_UNLCK checks any locks on the same fd. */
 977	if (lock_is_unlock(caller_fl)) {
 978		if (!posix_same_owner(caller, sys))
 979			return false;
 980		return locks_overlap(caller_fl, sys_fl);
 981	}
 982	return posix_locks_conflict(caller, sys);
 983}
 984
 985/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
 986 * checking before calling the locks_conflict().
 987 */
 988static bool flock_locks_conflict(struct file_lock_core *caller_flc,
 989				 struct file_lock_core *sys_flc)
 990{
 991	/* FLOCK locks referring to the same filp do not conflict with
 992	 * each other.
 993	 */
 994	if (caller_flc->flc_file == sys_flc->flc_file)
 995		return false;
 996
 997	return locks_conflict(caller_flc, sys_flc);
 998}
 999
1000void
1001posix_test_lock(struct file *filp, struct file_lock *fl)
1002{
1003	struct file_lock *cfl;
1004	struct file_lock_context *ctx;
1005	struct inode *inode = file_inode(filp);
1006	void *owner;
1007	void (*func)(void);
1008
1009	ctx = locks_inode_context(inode);
1010	if (!ctx || list_empty_careful(&ctx->flc_posix)) {
1011		fl->c.flc_type = F_UNLCK;
1012		return;
1013	}
1014
1015retry:
1016	spin_lock(&ctx->flc_lock);
1017	list_for_each_entry(cfl, &ctx->flc_posix, c.flc_list) {
1018		if (!posix_test_locks_conflict(fl, cfl))
1019			continue;
1020		if (cfl->fl_lmops && cfl->fl_lmops->lm_lock_expirable
1021			&& (*cfl->fl_lmops->lm_lock_expirable)(cfl)) {
1022			owner = cfl->fl_lmops->lm_mod_owner;
1023			func = cfl->fl_lmops->lm_expire_lock;
1024			__module_get(owner);
1025			spin_unlock(&ctx->flc_lock);
1026			(*func)();
1027			module_put(owner);
1028			goto retry;
1029		}
1030		locks_copy_conflock(fl, cfl);
1031		goto out;
1032	}
1033	fl->c.flc_type = F_UNLCK;
1034out:
1035	spin_unlock(&ctx->flc_lock);
1036	return;
1037}
1038EXPORT_SYMBOL(posix_test_lock);
1039
1040/*
1041 * Deadlock detection:
1042 *
1043 * We attempt to detect deadlocks that are due purely to posix file
1044 * locks.
1045 *
1046 * We assume that a task can be waiting for at most one lock at a time.
1047 * So for any acquired lock, the process holding that lock may be
1048 * waiting on at most one other lock.  That lock in turns may be held by
1049 * someone waiting for at most one other lock.  Given a requested lock
1050 * caller_fl which is about to wait for a conflicting lock block_fl, we
1051 * follow this chain of waiters to ensure we are not about to create a
1052 * cycle.
1053 *
1054 * Since we do this before we ever put a process to sleep on a lock, we
1055 * are ensured that there is never a cycle; that is what guarantees that
1056 * the while() loop in posix_locks_deadlock() eventually completes.
1057 *
1058 * Note: the above assumption may not be true when handling lock
1059 * requests from a broken NFS client. It may also fail in the presence
1060 * of tasks (such as posix threads) sharing the same open file table.
1061 * To handle those cases, we just bail out after a few iterations.
1062 *
1063 * For FL_OFDLCK locks, the owner is the filp, not the files_struct.
1064 * Because the owner is not even nominally tied to a thread of
1065 * execution, the deadlock detection below can't reasonably work well. Just
1066 * skip it for those.
1067 *
1068 * In principle, we could do a more limited deadlock detection on FL_OFDLCK
1069 * locks that just checks for the case where two tasks are attempting to
1070 * upgrade from read to write locks on the same inode.
1071 */
1072
1073#define MAX_DEADLK_ITERATIONS 10
1074
1075/* Find a lock that the owner of the given @blocker is blocking on. */
1076static struct file_lock_core *what_owner_is_waiting_for(struct file_lock_core *blocker)
1077{
1078	struct file_lock_core *flc;
1079
1080	hash_for_each_possible(blocked_hash, flc, flc_link, posix_owner_key(blocker)) {
1081		if (posix_same_owner(flc, blocker)) {
1082			while (flc->flc_blocker)
1083				flc = flc->flc_blocker;
1084			return flc;
1085		}
1086	}
1087	return NULL;
1088}
1089
1090/* Must be called with the blocked_lock_lock held! */
1091static bool posix_locks_deadlock(struct file_lock *caller_fl,
1092				 struct file_lock *block_fl)
1093{
1094	struct file_lock_core *caller = &caller_fl->c;
1095	struct file_lock_core *blocker = &block_fl->c;
1096	int i = 0;
1097
1098	lockdep_assert_held(&blocked_lock_lock);
1099
1100	/*
1101	 * This deadlock detector can't reasonably detect deadlocks with
1102	 * FL_OFDLCK locks, since they aren't owned by a process, per-se.
1103	 */
1104	if (caller->flc_flags & FL_OFDLCK)
1105		return false;
1106
1107	while ((blocker = what_owner_is_waiting_for(blocker))) {
1108		if (i++ > MAX_DEADLK_ITERATIONS)
1109			return false;
1110		if (posix_same_owner(caller, blocker))
1111			return true;
1112	}
1113	return false;
1114}
1115
1116/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
1117 * after any leases, but before any posix locks.
1118 *
1119 * Note that if called with an FL_EXISTS argument, the caller may determine
1120 * whether or not a lock was successfully freed by testing the return
1121 * value for -ENOENT.
1122 */
1123static int flock_lock_inode(struct inode *inode, struct file_lock *request)
1124{
1125	struct file_lock *new_fl = NULL;
1126	struct file_lock *fl;
1127	struct file_lock_context *ctx;
1128	int error = 0;
1129	bool found = false;
1130	LIST_HEAD(dispose);
1131
1132	ctx = locks_get_lock_context(inode, request->c.flc_type);
1133	if (!ctx) {
1134		if (request->c.flc_type != F_UNLCK)
1135			return -ENOMEM;
1136		return (request->c.flc_flags & FL_EXISTS) ? -ENOENT : 0;
1137	}
1138
1139	if (!(request->c.flc_flags & FL_ACCESS) && (request->c.flc_type != F_UNLCK)) {
1140		new_fl = locks_alloc_lock();
1141		if (!new_fl)
1142			return -ENOMEM;
1143	}
1144
1145	percpu_down_read(&file_rwsem);
1146	spin_lock(&ctx->flc_lock);
1147	if (request->c.flc_flags & FL_ACCESS)
1148		goto find_conflict;
1149
1150	list_for_each_entry(fl, &ctx->flc_flock, c.flc_list) {
1151		if (request->c.flc_file != fl->c.flc_file)
1152			continue;
1153		if (request->c.flc_type == fl->c.flc_type)
1154			goto out;
1155		found = true;
1156		locks_delete_lock_ctx(&fl->c, &dispose);
1157		break;
1158	}
1159
1160	if (lock_is_unlock(request)) {
1161		if ((request->c.flc_flags & FL_EXISTS) && !found)
1162			error = -ENOENT;
1163		goto out;
1164	}
1165
1166find_conflict:
1167	list_for_each_entry(fl, &ctx->flc_flock, c.flc_list) {
1168		if (!flock_locks_conflict(&request->c, &fl->c))
1169			continue;
1170		error = -EAGAIN;
1171		if (!(request->c.flc_flags & FL_SLEEP))
1172			goto out;
1173		error = FILE_LOCK_DEFERRED;
1174		locks_insert_block(&fl->c, &request->c, flock_locks_conflict);
1175		goto out;
1176	}
1177	if (request->c.flc_flags & FL_ACCESS)
1178		goto out;
1179	locks_copy_lock(new_fl, request);
1180	locks_move_blocks(new_fl, request);
1181	locks_insert_lock_ctx(&new_fl->c, &ctx->flc_flock);
1182	new_fl = NULL;
1183	error = 0;
1184
1185out:
1186	spin_unlock(&ctx->flc_lock);
1187	percpu_up_read(&file_rwsem);
1188	if (new_fl)
1189		locks_free_lock(new_fl);
1190	locks_dispose_list(&dispose);
1191	trace_flock_lock_inode(inode, request, error);
1192	return error;
1193}
1194
1195static int posix_lock_inode(struct inode *inode, struct file_lock *request,
1196			    struct file_lock *conflock)
1197{
1198	struct file_lock *fl, *tmp;
1199	struct file_lock *new_fl = NULL;
1200	struct file_lock *new_fl2 = NULL;
1201	struct file_lock *left = NULL;
1202	struct file_lock *right = NULL;
1203	struct file_lock_context *ctx;
1204	int error;
1205	bool added = false;
1206	LIST_HEAD(dispose);
1207	void *owner;
1208	void (*func)(void);
1209
1210	ctx = locks_get_lock_context(inode, request->c.flc_type);
1211	if (!ctx)
1212		return lock_is_unlock(request) ? 0 : -ENOMEM;
1213
1214	/*
1215	 * We may need two file_lock structures for this operation,
1216	 * so we get them in advance to avoid races.
1217	 *
1218	 * In some cases we can be sure, that no new locks will be needed
1219	 */
1220	if (!(request->c.flc_flags & FL_ACCESS) &&
1221	    (request->c.flc_type != F_UNLCK ||
1222	     request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
1223		new_fl = locks_alloc_lock();
1224		new_fl2 = locks_alloc_lock();
1225	}
1226
1227retry:
1228	percpu_down_read(&file_rwsem);
1229	spin_lock(&ctx->flc_lock);
1230	/*
1231	 * New lock request. Walk all POSIX locks and look for conflicts. If
1232	 * there are any, either return error or put the request on the
1233	 * blocker's list of waiters and the global blocked_hash.
1234	 */
1235	if (request->c.flc_type != F_UNLCK) {
1236		list_for_each_entry(fl, &ctx->flc_posix, c.flc_list) {
1237			if (!posix_locks_conflict(&request->c, &fl->c))
1238				continue;
1239			if (fl->fl_lmops && fl->fl_lmops->lm_lock_expirable
1240				&& (*fl->fl_lmops->lm_lock_expirable)(fl)) {
1241				owner = fl->fl_lmops->lm_mod_owner;
1242				func = fl->fl_lmops->lm_expire_lock;
1243				__module_get(owner);
1244				spin_unlock(&ctx->flc_lock);
1245				percpu_up_read(&file_rwsem);
1246				(*func)();
1247				module_put(owner);
1248				goto retry;
1249			}
1250			if (conflock)
1251				locks_copy_conflock(conflock, fl);
1252			error = -EAGAIN;
1253			if (!(request->c.flc_flags & FL_SLEEP))
1254				goto out;
1255			/*
1256			 * Deadlock detection and insertion into the blocked
1257			 * locks list must be done while holding the same lock!
1258			 */
1259			error = -EDEADLK;
1260			spin_lock(&blocked_lock_lock);
1261			/*
1262			 * Ensure that we don't find any locks blocked on this
1263			 * request during deadlock detection.
1264			 */
1265			__locks_wake_up_blocks(&request->c);
1266			if (likely(!posix_locks_deadlock(request, fl))) {
1267				error = FILE_LOCK_DEFERRED;
1268				__locks_insert_block(&fl->c, &request->c,
1269						     posix_locks_conflict);
1270			}
1271			spin_unlock(&blocked_lock_lock);
1272			goto out;
1273		}
1274	}
1275
1276	/* If we're just looking for a conflict, we're done. */
1277	error = 0;
1278	if (request->c.flc_flags & FL_ACCESS)
1279		goto out;
1280
1281	/* Find the first old lock with the same owner as the new lock */
1282	list_for_each_entry(fl, &ctx->flc_posix, c.flc_list) {
1283		if (posix_same_owner(&request->c, &fl->c))
1284			break;
1285	}
1286
1287	/* Process locks with this owner. */
1288	list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, c.flc_list) {
1289		if (!posix_same_owner(&request->c, &fl->c))
1290			break;
1291
1292		/* Detect adjacent or overlapping regions (if same lock type) */
1293		if (request->c.flc_type == fl->c.flc_type) {
1294			/* In all comparisons of start vs end, use
1295			 * "start - 1" rather than "end + 1". If end
1296			 * is OFFSET_MAX, end + 1 will become negative.
1297			 */
1298			if (fl->fl_end < request->fl_start - 1)
1299				continue;
1300			/* If the next lock in the list has entirely bigger
1301			 * addresses than the new one, insert the lock here.
1302			 */
1303			if (fl->fl_start - 1 > request->fl_end)
1304				break;
1305
1306			/* If we come here, the new and old lock are of the
1307			 * same type and adjacent or overlapping. Make one
1308			 * lock yielding from the lower start address of both
1309			 * locks to the higher end address.
1310			 */
1311			if (fl->fl_start > request->fl_start)
1312				fl->fl_start = request->fl_start;
1313			else
1314				request->fl_start = fl->fl_start;
1315			if (fl->fl_end < request->fl_end)
1316				fl->fl_end = request->fl_end;
1317			else
1318				request->fl_end = fl->fl_end;
1319			if (added) {
1320				locks_delete_lock_ctx(&fl->c, &dispose);
1321				continue;
1322			}
1323			request = fl;
1324			added = true;
1325		} else {
1326			/* Processing for different lock types is a bit
1327			 * more complex.
1328			 */
1329			if (fl->fl_end < request->fl_start)
1330				continue;
1331			if (fl->fl_start > request->fl_end)
1332				break;
1333			if (lock_is_unlock(request))
1334				added = true;
1335			if (fl->fl_start < request->fl_start)
1336				left = fl;
1337			/* If the next lock in the list has a higher end
1338			 * address than the new one, insert the new one here.
1339			 */
1340			if (fl->fl_end > request->fl_end) {
1341				right = fl;
1342				break;
1343			}
1344			if (fl->fl_start >= request->fl_start) {
1345				/* The new lock completely replaces an old
1346				 * one (This may happen several times).
1347				 */
1348				if (added) {
1349					locks_delete_lock_ctx(&fl->c, &dispose);
1350					continue;
1351				}
1352				/*
1353				 * Replace the old lock with new_fl, and
1354				 * remove the old one. It's safe to do the
1355				 * insert here since we know that we won't be
1356				 * using new_fl later, and that the lock is
1357				 * just replacing an existing lock.
1358				 */
1359				error = -ENOLCK;
1360				if (!new_fl)
1361					goto out;
1362				locks_copy_lock(new_fl, request);
1363				locks_move_blocks(new_fl, request);
1364				request = new_fl;
1365				new_fl = NULL;
1366				locks_insert_lock_ctx(&request->c,
1367						      &fl->c.flc_list);
1368				locks_delete_lock_ctx(&fl->c, &dispose);
1369				added = true;
1370			}
1371		}
1372	}
1373
1374	/*
1375	 * The above code only modifies existing locks in case of merging or
1376	 * replacing. If new lock(s) need to be inserted all modifications are
1377	 * done below this, so it's safe yet to bail out.
1378	 */
1379	error = -ENOLCK; /* "no luck" */
1380	if (right && left == right && !new_fl2)
1381		goto out;
1382
1383	error = 0;
1384	if (!added) {
1385		if (lock_is_unlock(request)) {
1386			if (request->c.flc_flags & FL_EXISTS)
1387				error = -ENOENT;
1388			goto out;
1389		}
1390
1391		if (!new_fl) {
1392			error = -ENOLCK;
1393			goto out;
1394		}
1395		locks_copy_lock(new_fl, request);
1396		locks_move_blocks(new_fl, request);
1397		locks_insert_lock_ctx(&new_fl->c, &fl->c.flc_list);
1398		fl = new_fl;
1399		new_fl = NULL;
1400	}
1401	if (right) {
1402		if (left == right) {
1403			/* The new lock breaks the old one in two pieces,
1404			 * so we have to use the second new lock.
1405			 */
1406			left = new_fl2;
1407			new_fl2 = NULL;
1408			locks_copy_lock(left, right);
1409			locks_insert_lock_ctx(&left->c, &fl->c.flc_list);
1410		}
1411		right->fl_start = request->fl_end + 1;
1412		locks_wake_up_blocks(&right->c);
1413	}
1414	if (left) {
1415		left->fl_end = request->fl_start - 1;
1416		locks_wake_up_blocks(&left->c);
1417	}
1418 out:
1419	trace_posix_lock_inode(inode, request, error);
1420	spin_unlock(&ctx->flc_lock);
1421	percpu_up_read(&file_rwsem);
1422	/*
1423	 * Free any unused locks.
1424	 */
1425	if (new_fl)
1426		locks_free_lock(new_fl);
1427	if (new_fl2)
1428		locks_free_lock(new_fl2);
1429	locks_dispose_list(&dispose);
1430
1431	return error;
1432}
1433
1434/**
1435 * posix_lock_file - Apply a POSIX-style lock to a file
1436 * @filp: The file to apply the lock to
1437 * @fl: The lock to be applied
1438 * @conflock: Place to return a copy of the conflicting lock, if found.
1439 *
1440 * Add a POSIX style lock to a file.
1441 * We merge adjacent & overlapping locks whenever possible.
1442 * POSIX locks are sorted by owner task, then by starting address
1443 *
1444 * Note that if called with an FL_EXISTS argument, the caller may determine
1445 * whether or not a lock was successfully freed by testing the return
1446 * value for -ENOENT.
1447 */
1448int posix_lock_file(struct file *filp, struct file_lock *fl,
1449			struct file_lock *conflock)
1450{
1451	return posix_lock_inode(file_inode(filp), fl, conflock);
1452}
1453EXPORT_SYMBOL(posix_lock_file);
1454
1455/**
1456 * posix_lock_inode_wait - Apply a POSIX-style lock to a file
1457 * @inode: inode of file to which lock request should be applied
1458 * @fl: The lock to be applied
1459 *
1460 * Apply a POSIX style lock request to an inode.
1461 */
1462static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl)
1463{
1464	int error;
1465	might_sleep ();
1466	for (;;) {
1467		error = posix_lock_inode(inode, fl, NULL);
1468		if (error != FILE_LOCK_DEFERRED)
1469			break;
1470		error = wait_event_interruptible(fl->c.flc_wait,
1471						 list_empty(&fl->c.flc_blocked_member));
1472		if (error)
1473			break;
1474	}
1475	locks_delete_block(fl);
1476	return error;
1477}
1478
1479static void lease_clear_pending(struct file_lease *fl, int arg)
1480{
1481	switch (arg) {
1482	case F_UNLCK:
1483		fl->c.flc_flags &= ~FL_UNLOCK_PENDING;
1484		fallthrough;
1485	case F_RDLCK:
1486		fl->c.flc_flags &= ~FL_DOWNGRADE_PENDING;
1487	}
1488}
1489
1490/* We already had a lease on this file; just change its type */
1491int lease_modify(struct file_lease *fl, int arg, struct list_head *dispose)
1492{
1493	int error = assign_type(&fl->c, arg);
1494
1495	if (error)
1496		return error;
1497	lease_clear_pending(fl, arg);
1498	locks_wake_up_blocks(&fl->c);
1499	if (arg == F_UNLCK) {
1500		struct file *filp = fl->c.flc_file;
1501
1502		f_delown(filp);
1503		file_f_owner(filp)->signum = 0;
1504		fasync_helper(0, fl->c.flc_file, 0, &fl->fl_fasync);
1505		if (fl->fl_fasync != NULL) {
1506			printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
1507			fl->fl_fasync = NULL;
1508		}
1509		locks_delete_lock_ctx(&fl->c, dispose);
1510	}
1511	return 0;
1512}
1513EXPORT_SYMBOL(lease_modify);
1514
1515static bool past_time(unsigned long then)
1516{
1517	if (!then)
1518		/* 0 is a special value meaning "this never expires": */
1519		return false;
1520	return time_after(jiffies, then);
1521}
1522
1523static void time_out_leases(struct inode *inode, struct list_head *dispose)
1524{
1525	struct file_lock_context *ctx = inode->i_flctx;
1526	struct file_lease *fl, *tmp;
1527
1528	lockdep_assert_held(&ctx->flc_lock);
1529
1530	list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, c.flc_list) {
1531		trace_time_out_leases(inode, fl);
1532		if (past_time(fl->fl_downgrade_time))
1533			lease_modify(fl, F_RDLCK, dispose);
1534		if (past_time(fl->fl_break_time))
1535			lease_modify(fl, F_UNLCK, dispose);
1536	}
1537}
1538
1539static bool leases_conflict(struct file_lock_core *lc, struct file_lock_core *bc)
1540{
1541	bool rc;
1542	struct file_lease *lease = file_lease(lc);
1543	struct file_lease *breaker = file_lease(bc);
1544
1545	if (lease->fl_lmops->lm_breaker_owns_lease
1546			&& lease->fl_lmops->lm_breaker_owns_lease(lease))
1547		return false;
1548	if ((bc->flc_flags & FL_LAYOUT) != (lc->flc_flags & FL_LAYOUT)) {
1549		rc = false;
1550		goto trace;
1551	}
1552	if ((bc->flc_flags & FL_DELEG) && (lc->flc_flags & FL_LEASE)) {
1553		rc = false;
1554		goto trace;
1555	}
1556
1557	rc = locks_conflict(bc, lc);
1558trace:
1559	trace_leases_conflict(rc, lease, breaker);
1560	return rc;
1561}
1562
1563static bool
1564any_leases_conflict(struct inode *inode, struct file_lease *breaker)
1565{
1566	struct file_lock_context *ctx = inode->i_flctx;
1567	struct file_lock_core *flc;
1568
1569	lockdep_assert_held(&ctx->flc_lock);
1570
1571	list_for_each_entry(flc, &ctx->flc_lease, flc_list) {
1572		if (leases_conflict(flc, &breaker->c))
1573			return true;
1574	}
1575	return false;
1576}
1577
1578/**
1579 *	__break_lease	-	revoke all outstanding leases on file
1580 *	@inode: the inode of the file to return
1581 *	@flags: LEASE_BREAK_* flags
1582 *
1583 *	break_lease (inlined for speed) has checked there already is at least
1584 *	some kind of lock (maybe a lease) on this file.  Leases are broken on
1585 *	a call to open() or truncate().  This function can block waiting for the
1586 *	lease break unless you specify LEASE_BREAK_NONBLOCK.
1587 */
1588int __break_lease(struct inode *inode, unsigned int flags)
1589{
1590	struct file_lease *new_fl, *fl, *tmp;
1591	struct file_lock_context *ctx;
1592	unsigned long break_time;
1593	unsigned int type;
1594	LIST_HEAD(dispose);
1595	bool want_write = !(flags & LEASE_BREAK_OPEN_RDONLY);
1596	int error = 0;
1597
1598	if (flags & LEASE_BREAK_LEASE)
1599		type = FL_LEASE;
1600	else if (flags & LEASE_BREAK_DELEG)
1601		type = FL_DELEG;
1602	else if (flags & LEASE_BREAK_LAYOUT)
1603		type = FL_LAYOUT;
1604	else
1605		return -EINVAL;
1606
1607	new_fl = lease_alloc(NULL, type, want_write ? F_WRLCK : F_RDLCK);
1608	if (IS_ERR(new_fl))
1609		return PTR_ERR(new_fl);
1610
1611	/* typically we will check that ctx is non-NULL before calling */
1612	ctx = locks_inode_context(inode);
1613	if (!ctx) {
1614		WARN_ON_ONCE(1);
1615		goto free_lock;
1616	}
1617
1618	percpu_down_read(&file_rwsem);
1619	spin_lock(&ctx->flc_lock);
1620
1621	time_out_leases(inode, &dispose);
1622
1623	if (!any_leases_conflict(inode, new_fl))
1624		goto out;
1625
1626	break_time = 0;
1627	if (lease_break_time > 0) {
1628		break_time = jiffies + lease_break_time * HZ;
1629		if (break_time == 0)
1630			break_time++;	/* so that 0 means no break time */
1631	}
1632
1633	list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, c.flc_list) {
1634		if (!leases_conflict(&fl->c, &new_fl->c))
1635			continue;
1636		if (want_write) {
1637			if (fl->c.flc_flags & FL_UNLOCK_PENDING)
1638				continue;
1639			fl->c.flc_flags |= FL_UNLOCK_PENDING;
1640			fl->fl_break_time = break_time;
1641		} else {
1642			if (lease_breaking(fl))
1643				continue;
1644			fl->c.flc_flags |= FL_DOWNGRADE_PENDING;
1645			fl->fl_downgrade_time = break_time;
1646		}
1647		if (fl->fl_lmops->lm_break(fl))
1648			locks_delete_lock_ctx(&fl->c, &dispose);
1649	}
1650
1651	if (list_empty(&ctx->flc_lease))
1652		goto out;
1653
1654	if (flags & LEASE_BREAK_NONBLOCK) {
1655		trace_break_lease_noblock(inode, new_fl);
1656		error = -EWOULDBLOCK;
1657		goto out;
1658	}
1659
1660restart:
1661	fl = list_first_entry(&ctx->flc_lease, struct file_lease, c.flc_list);
1662	break_time = fl->fl_break_time;
1663	if (break_time != 0)
1664		break_time -= jiffies;
1665	if (break_time == 0)
1666		break_time++;
1667	locks_insert_block(&fl->c, &new_fl->c, leases_conflict);
1668	trace_break_lease_block(inode, new_fl);
1669	spin_unlock(&ctx->flc_lock);
1670	percpu_up_read(&file_rwsem);
1671
1672	lease_dispose_list(&dispose);
1673	error = wait_event_interruptible_timeout(new_fl->c.flc_wait,
1674						 list_empty(&new_fl->c.flc_blocked_member),
1675						 break_time);
1676
1677	percpu_down_read(&file_rwsem);
1678	spin_lock(&ctx->flc_lock);
1679	trace_break_lease_unblock(inode, new_fl);
1680	__locks_delete_block(&new_fl->c);
1681	if (error >= 0) {
1682		/*
1683		 * Wait for the next conflicting lease that has not been
1684		 * broken yet
1685		 */
1686		if (error == 0)
1687			time_out_leases(inode, &dispose);
1688		if (any_leases_conflict(inode, new_fl))
1689			goto restart;
1690		error = 0;
1691	}
1692out:
1693	spin_unlock(&ctx->flc_lock);
1694	percpu_up_read(&file_rwsem);
1695	lease_dispose_list(&dispose);
1696free_lock:
1697	locks_free_lease(new_fl);
1698	return error;
1699}
1700EXPORT_SYMBOL(__break_lease);
1701
1702/**
1703 *	lease_get_mtime - update modified time of an inode with exclusive lease
1704 *	@inode: the inode
1705 *      @time:  pointer to a timespec which contains the last modified time
1706 *
1707 * This is to force NFS clients to flush their caches for files with
1708 * exclusive leases.  The justification is that if someone has an
1709 * exclusive lease, then they could be modifying it.
1710 */
1711void lease_get_mtime(struct inode *inode, struct timespec64 *time)
1712{
1713	bool has_lease = false;
1714	struct file_lock_context *ctx;
1715	struct file_lock_core *flc;
1716
1717	ctx = locks_inode_context(inode);
1718	if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1719		spin_lock(&ctx->flc_lock);
1720		flc = list_first_entry_or_null(&ctx->flc_lease,
1721					       struct file_lock_core, flc_list);
1722		if (flc && flc->flc_type == F_WRLCK)
1723			has_lease = true;
1724		spin_unlock(&ctx->flc_lock);
1725	}
1726
1727	if (has_lease)
1728		*time = current_time(inode);
1729}
1730EXPORT_SYMBOL(lease_get_mtime);
1731
1732/**
1733 *	__fcntl_getlease - Enquire what lease is currently active
1734 *	@filp: the file
1735 *	@flavor: type of lease flags to check
1736 *
1737 *	The value returned by this function will be one of
1738 *	(if no lease break is pending):
1739 *
1740 *	%F_RDLCK to indicate a shared lease is held.
1741 *
1742 *	%F_WRLCK to indicate an exclusive lease is held.
1743 *
1744 *	%F_UNLCK to indicate no lease is held.
1745 *
1746 *	(if a lease break is pending):
1747 *
1748 *	%F_RDLCK to indicate an exclusive lease needs to be
1749 *		changed to a shared lease (or removed).
1750 *
1751 *	%F_UNLCK to indicate the lease needs to be removed.
1752 *
1753 *	XXX: sfr & willy disagree over whether F_INPROGRESS
1754 *	should be returned to userspace.
1755 */
1756static int __fcntl_getlease(struct file *filp, unsigned int flavor)
1757{
1758	struct file_lease *fl;
1759	struct inode *inode = file_inode(filp);
1760	struct file_lock_context *ctx;
1761	int type = F_UNLCK;
1762	LIST_HEAD(dispose);
1763
1764	ctx = locks_inode_context(inode);
1765	if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1766		percpu_down_read(&file_rwsem);
1767		spin_lock(&ctx->flc_lock);
1768		time_out_leases(inode, &dispose);
1769		list_for_each_entry(fl, &ctx->flc_lease, c.flc_list) {
1770			if (fl->c.flc_file != filp)
1771				continue;
1772			if (fl->c.flc_flags & flavor)
1773				type = target_leasetype(fl);
1774			break;
1775		}
1776		spin_unlock(&ctx->flc_lock);
1777		percpu_up_read(&file_rwsem);
1778
1779		lease_dispose_list(&dispose);
1780	}
1781	return type;
1782}
1783
1784int fcntl_getlease(struct file *filp)
1785{
1786	return __fcntl_getlease(filp, FL_LEASE);
1787}
1788
1789int fcntl_getdeleg(struct file *filp, struct delegation *deleg)
1790{
1791	if (deleg->d_flags != 0 || deleg->__pad != 0)
1792		return -EINVAL;
1793	deleg->d_type = __fcntl_getlease(filp, FL_DELEG);
1794	return 0;
1795}
1796
1797static int
1798generic_add_lease(struct file *filp, int arg, struct file_lease **flp, void **priv)
1799{
1800	struct file_lease *fl, *my_fl = NULL, *lease;
1801	struct inode *inode = file_inode(filp);
1802	struct file_lock_context *ctx;
1803	bool is_deleg = (*flp)->c.flc_flags & FL_DELEG;
1804	int error;
1805	LIST_HEAD(dispose);
1806
1807	lease = *flp;
1808	trace_generic_add_lease(inode, lease);
1809
1810	error = file_f_owner_allocate(filp);
1811	if (error)
1812		return error;
1813
1814	/* Note that arg is never F_UNLCK here */
1815	ctx = locks_get_lock_context(inode, arg);
1816	if (!ctx)
1817		return -ENOMEM;
1818
1819	/*
1820	 * In the delegation case we need mutual exclusion with
1821	 * a number of operations that take the i_rwsem.  We trylock
1822	 * because delegations are an optional optimization, and if
1823	 * there's some chance of a conflict--we'd rather not
1824	 * bother, maybe that's a sign this just isn't a good file to
1825	 * hand out a delegation on.
1826	 */
1827	if (is_deleg && !inode_trylock(inode))
1828		return -EAGAIN;
1829
1830	percpu_down_read(&file_rwsem);
1831	spin_lock(&ctx->flc_lock);
1832	time_out_leases(inode, &dispose);
1833	error = lease->fl_lmops->lm_open_conflict(filp, arg);
1834	if (error)
1835		goto out;
1836
1837	/*
1838	 * At this point, we know that if there is an exclusive
1839	 * lease on this file, then we hold it on this filp
1840	 * (otherwise our open of this file would have blocked).
1841	 * And if we are trying to acquire an exclusive lease,
1842	 * then the file is not open by anyone (including us)
1843	 * except for this filp.
1844	 */
1845	error = -EAGAIN;
1846	list_for_each_entry(fl, &ctx->flc_lease, c.flc_list) {
1847		if (fl->c.flc_file == filp &&
1848		    fl->c.flc_owner == lease->c.flc_owner) {
1849			my_fl = fl;
1850			continue;
1851		}
1852
1853		/*
1854		 * No exclusive leases if someone else has a lease on
1855		 * this file:
1856		 */
1857		if (arg == F_WRLCK)
1858			goto out;
1859		/*
1860		 * Modifying our existing lease is OK, but no getting a
1861		 * new lease if someone else is opening for write:
1862		 */
1863		if (fl->c.flc_flags & FL_UNLOCK_PENDING)
1864			goto out;
1865	}
1866
1867	if (my_fl != NULL) {
1868		lease = my_fl;
1869		error = lease->fl_lmops->lm_change(lease, arg, &dispose);
1870		if (error)
1871			goto out;
1872		goto out_setup;
1873	}
1874
1875	error = -EINVAL;
1876	if (!leases_enable)
1877		goto out;
1878
1879	locks_insert_lock_ctx(&lease->c, &ctx->flc_lease);
1880	/*
1881	 * The check in break_lease() is lockless. It's possible for another
1882	 * open to race in after we did the earlier check for a conflicting
1883	 * open but before the lease was inserted. Check again for a
1884	 * conflicting open and cancel the lease if there is one.
1885	 *
1886	 * We also add a barrier here to ensure that the insertion of the lock
1887	 * precedes these checks.
1888	 */
1889	smp_mb();
1890	error = lease->fl_lmops->lm_open_conflict(filp, arg);
1891	if (error) {
1892		locks_unlink_lock_ctx(&lease->c);
1893		goto out;
1894	}
1895
1896out_setup:
1897	if (lease->fl_lmops->lm_setup)
1898		lease->fl_lmops->lm_setup(lease, priv);
1899out:
1900	spin_unlock(&ctx->flc_lock);
1901	percpu_up_read(&file_rwsem);
1902	lease_dispose_list(&dispose);
1903	if (is_deleg)
1904		inode_unlock(inode);
1905	if (!error && !my_fl)
1906		*flp = NULL;
1907	return error;
1908}
1909
1910static int generic_delete_lease(struct file *filp, void *owner)
1911{
1912	int error = -EAGAIN;
1913	struct file_lease *fl, *victim = NULL;
1914	struct inode *inode = file_inode(filp);
1915	struct file_lock_context *ctx;
1916	LIST_HEAD(dispose);
1917
1918	ctx = locks_inode_context(inode);
1919	if (!ctx) {
1920		trace_generic_delete_lease(inode, NULL);
1921		return error;
1922	}
1923
1924	percpu_down_read(&file_rwsem);
1925	spin_lock(&ctx->flc_lock);
1926	list_for_each_entry(fl, &ctx->flc_lease, c.flc_list) {
1927		if (fl->c.flc_file == filp &&
1928		    fl->c.flc_owner == owner) {
1929			victim = fl;
1930			break;
1931		}
1932	}
1933	trace_generic_delete_lease(inode, victim);
1934	if (victim)
1935		error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose);
1936	spin_unlock(&ctx->flc_lock);
1937	percpu_up_read(&file_rwsem);
1938	lease_dispose_list(&dispose);
1939	return error;
1940}
1941
1942/**
1943 *	generic_setlease	-	sets a lease on an open file
1944 *	@filp:	file pointer
1945 *	@arg:	type of lease to obtain
1946 *	@flp:	input - file_lock to use, output - file_lock inserted
1947 *	@priv:	private data for lm_setup (may be NULL if lm_setup
1948 *		doesn't require it)
1949 *
1950 *	The (input) flp->fl_lmops->lm_break function is required
1951 *	by break_lease().
1952 */
1953int generic_setlease(struct file *filp, int arg, struct file_lease **flp,
1954			void **priv)
1955{
1956	struct inode *inode = file_inode(filp);
1957
1958	if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
1959		return -EINVAL;
1960
1961	switch (arg) {
1962	case F_UNLCK:
1963		return generic_delete_lease(filp, *priv);
1964	case F_WRLCK:
1965		if (S_ISDIR(inode->i_mode))
1966			return -EINVAL;
1967		fallthrough;
1968	case F_RDLCK:
1969		if (!(*flp)->fl_lmops->lm_break) {
1970			WARN_ON_ONCE(1);
1971			return -ENOLCK;
1972		}
1973
1974		return generic_add_lease(filp, arg, flp, priv);
1975	default:
1976		return -EINVAL;
1977	}
1978}
1979EXPORT_SYMBOL(generic_setlease);
1980
1981/*
1982 * Kernel subsystems can register to be notified on any attempt to set
1983 * a new lease with the lease_notifier_chain. This is used by (e.g.) nfsd
1984 * to close files that it may have cached when there is an attempt to set a
1985 * conflicting lease.
1986 */
1987static struct srcu_notifier_head lease_notifier_chain;
1988
1989static inline void
1990lease_notifier_chain_init(void)
1991{
1992	srcu_init_notifier_head(&lease_notifier_chain);
1993}
1994
1995static inline void
1996setlease_notifier(int arg, struct file_lease *lease)
1997{
1998	if (arg != F_UNLCK)
1999		srcu_notifier_call_chain(&lease_notifier_chain, arg, lease);
2000}
2001
2002int lease_register_notifier(struct notifier_block *nb)
2003{
2004	return srcu_notifier_chain_register(&lease_notifier_chain, nb);
2005}
2006EXPORT_SYMBOL_GPL(lease_register_notifier);
2007
2008void lease_unregister_notifier(struct notifier_block *nb)
2009{
2010	srcu_notifier_chain_unregister(&lease_notifier_chain, nb);
2011}
2012EXPORT_SYMBOL_GPL(lease_unregister_notifier);
2013
2014
2015int
2016kernel_setlease(struct file *filp, int arg, struct file_lease **lease, void **priv)
2017{
2018	if (lease)
2019		setlease_notifier(arg, *lease);
2020	if (filp->f_op->setlease)
2021		return filp->f_op->setlease(filp, arg, lease, priv);
2022	else
2023		return generic_setlease(filp, arg, lease, priv);
2024}
2025EXPORT_SYMBOL_GPL(kernel_setlease);
2026
2027/**
2028 * vfs_setlease        -       sets a lease on an open file
2029 * @filp:	file pointer
2030 * @arg:	type of lease to obtain
2031 * @lease:	file_lock to use when adding a lease
2032 * @priv:	private info for lm_setup when adding a lease (may be
2033 *		NULL if lm_setup doesn't require it)
2034 *
2035 * Call this to establish a lease on the file. The "lease" argument is not
2036 * used for F_UNLCK requests and may be NULL. For commands that set or alter
2037 * an existing lease, the ``(*lease)->fl_lmops->lm_break`` operation must be
2038 * set; if not, this function will return -ENOLCK (and generate a scary-looking
2039 * stack trace).
2040 *
2041 * The "priv" pointer is passed directly to the lm_setup function as-is. It
2042 * may be NULL if the lm_setup operation doesn't require it.
2043 */
2044int
2045vfs_setlease(struct file *filp, int arg, struct file_lease **lease, void **priv)
2046{
2047	struct inode *inode = file_inode(filp);
2048	vfsuid_t vfsuid = i_uid_into_vfsuid(file_mnt_idmap(filp), inode);
2049	int error;
2050
2051	if ((!vfsuid_eq_kuid(vfsuid, current_fsuid())) && !capable(CAP_LEASE))
2052		return -EACCES;
2053	error = security_file_lock(filp, arg);
2054	if (error)
2055		return error;
2056	return kernel_setlease(filp, arg, lease, priv);
2057}
2058EXPORT_SYMBOL_GPL(vfs_setlease);
2059
2060static int do_fcntl_add_lease(unsigned int fd, struct file *filp, unsigned int flavor, int arg)
2061{
2062	struct file_lease *fl;
2063	struct fasync_struct *new;
2064	int error;
2065
2066	fl = lease_alloc(filp, flavor, arg);
2067	if (IS_ERR(fl))
2068		return PTR_ERR(fl);
2069
2070	new = fasync_alloc();
2071	if (!new) {
2072		locks_free_lease(fl);
2073		return -ENOMEM;
2074	}
2075	new->fa_fd = fd;
2076
2077	error = vfs_setlease(filp, arg, &fl, (void **)&new);
2078	if (fl)
2079		locks_free_lease(fl);
2080	if (new)
2081		fasync_free(new);
2082	return error;
2083}
2084
2085/**
2086 *	fcntl_setlease	-	sets a lease on an open file
2087 *	@fd: open file descriptor
2088 *	@filp: file pointer
2089 *	@arg: type of lease to obtain
2090 *
2091 *	Call this fcntl to establish a lease on the file.
2092 *	Note that you also need to call %F_SETSIG to
2093 *	receive a signal when the lease is broken.
2094 */
2095int fcntl_setlease(unsigned int fd, struct file *filp, int arg)
2096{
2097	if (S_ISDIR(file_inode(filp)->i_mode))
2098		return -EINVAL;
2099
2100	if (arg == F_UNLCK)
2101		return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp);
2102	return do_fcntl_add_lease(fd, filp, FL_LEASE, arg);
2103}
2104
2105/**
2106 *	fcntl_setdeleg	-	sets a delegation on an open file
2107 *	@fd: open file descriptor
2108 *	@filp: file pointer
2109 *	@deleg: delegation request from userland
2110 *
2111 *	Call this fcntl to establish a delegation on the file.
2112 *	Note that you also need to call %F_SETSIG to
2113 *	receive a signal when the lease is broken.
2114 */
2115int fcntl_setdeleg(unsigned int fd, struct file *filp, struct delegation *deleg)
2116{
2117	/* For now, no flags are supported */
2118	if (deleg->d_flags != 0 || deleg->__pad != 0)
2119		return -EINVAL;
2120
2121	if (deleg->d_type == F_UNLCK)
2122		return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp);
2123	return do_fcntl_add_lease(fd, filp, FL_DELEG, deleg->d_type);
2124}
2125
2126/**
2127 * flock_lock_inode_wait - Apply a FLOCK-style lock to a file
2128 * @inode: inode of the file to apply to
2129 * @fl: The lock to be applied
2130 *
2131 * Apply a FLOCK style lock request to an inode.
2132 */
2133static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl)
2134{
2135	int error;
2136	might_sleep();
2137	for (;;) {
2138		error = flock_lock_inode(inode, fl);
2139		if (error != FILE_LOCK_DEFERRED)
2140			break;
2141		error = wait_event_interruptible(fl->c.flc_wait,
2142						 list_empty(&fl->c.flc_blocked_member));
2143		if (error)
2144			break;
2145	}
2146	locks_delete_block(fl);
2147	return error;
2148}
2149
2150/**
2151 * locks_lock_inode_wait - Apply a lock to an inode
2152 * @inode: inode of the file to apply to
2153 * @fl: The lock to be applied
2154 *
2155 * Apply a POSIX or FLOCK style lock request to an inode.
2156 */
2157int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl)
2158{
2159	int res = 0;
2160	switch (fl->c.flc_flags & (FL_POSIX|FL_FLOCK)) {
2161		case FL_POSIX:
2162			res = posix_lock_inode_wait(inode, fl);
2163			break;
2164		case FL_FLOCK:
2165			res = flock_lock_inode_wait(inode, fl);
2166			break;
2167		default:
2168			BUG();
2169	}
2170	return res;
2171}
2172EXPORT_SYMBOL(locks_lock_inode_wait);
2173
2174/**
2175 *	sys_flock: - flock() system call.
2176 *	@fd: the file descriptor to lock.
2177 *	@cmd: the type of lock to apply.
2178 *
2179 *	Apply a %FL_FLOCK style lock to an open file descriptor.
2180 *	The @cmd can be one of:
2181 *
2182 *	- %LOCK_SH -- a shared lock.
2183 *	- %LOCK_EX -- an exclusive lock.
2184 *	- %LOCK_UN -- remove an existing lock.
2185 *	- %LOCK_MAND -- a 'mandatory' flock. (DEPRECATED)
2186 *
2187 *	%LOCK_MAND support has been removed from the kernel.
2188 */
2189SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
2190{
2191	int can_sleep, error, type;
2192	struct file_lock fl;
2193
2194	/*
2195	 * LOCK_MAND locks were broken for a long time in that they never
2196	 * conflicted with one another and didn't prevent any sort of open,
2197	 * read or write activity.
2198	 *
2199	 * Just ignore these requests now, to preserve legacy behavior, but
2200	 * throw a warning to let people know that they don't actually work.
2201	 */
2202	if (cmd & LOCK_MAND) {
2203		pr_warn_once("%s(%d): Attempt to set a LOCK_MAND lock via flock(2). This support has been removed and the request ignored.\n", current->comm, current->pid);
2204		return 0;
2205	}
2206
2207	type = flock_translate_cmd(cmd & ~LOCK_NB);
2208	if (type < 0)
2209		return type;
2210
2211	CLASS(fd, f)(fd);
2212	if (fd_empty(f))
2213		return -EBADF;
2214
2215	if (type != F_UNLCK && !(fd_file(f)->f_mode & (FMODE_READ | FMODE_WRITE)))
2216		return -EBADF;
2217
2218	flock_make_lock(fd_file(f), &fl, type);
2219
2220	error = security_file_lock(fd_file(f), fl.c.flc_type);
2221	if (error)
2222		return error;
2223
2224	can_sleep = !(cmd & LOCK_NB);
2225	if (can_sleep)
2226		fl.c.flc_flags |= FL_SLEEP;
2227
2228	if (fd_file(f)->f_op->flock)
2229		error = fd_file(f)->f_op->flock(fd_file(f),
2230					    (can_sleep) ? F_SETLKW : F_SETLK,
2231					    &fl);
2232	else
2233		error = locks_lock_file_wait(fd_file(f), &fl);
2234
2235	locks_release_private(&fl);
2236	return error;
2237}
2238
2239/**
2240 * vfs_test_lock - test file byte range lock
2241 * @filp: The file to test lock for
2242 * @fl: The byte-range in the file to test; also used to hold result
2243 *
2244 * On entry, @fl does not contain a lock, but identifies a range (fl_start, fl_end)
2245 * in the file (c.flc_file), and an owner (c.flc_owner) for whom existing locks
2246 * should be ignored.  c.flc_type and c.flc_flags are ignored.
2247 * Both fl_lmops and fl_ops in @fl must be NULL.
2248 * Returns -ERRNO on failure.  Indicates presence of conflicting lock by
2249 * setting fl->fl_type to something other than F_UNLCK.
2250 *
2251 * If vfs_test_lock() does find a lock and return it, the caller must
2252 * use locks_free_lock() or locks_release_private() on the returned lock.
2253 */
2254int vfs_test_lock(struct file *filp, struct file_lock *fl)
2255{
2256	WARN_ON_ONCE(fl->fl_ops || fl->fl_lmops);
2257	WARN_ON_ONCE(filp != fl->c.flc_file);
2258	if (filp->f_op->lock)
2259		return filp->f_op->lock(filp, F_GETLK, fl);
2260	posix_test_lock(filp, fl);
2261	return 0;
2262}
2263EXPORT_SYMBOL_GPL(vfs_test_lock);
2264
2265/**
2266 * locks_translate_pid - translate a file_lock's fl_pid number into a namespace
2267 * @fl: The file_lock who's fl_pid should be translated
2268 * @ns: The namespace into which the pid should be translated
2269 *
2270 * Used to translate a fl_pid into a namespace virtual pid number
2271 */
2272static pid_t locks_translate_pid(struct file_lock_core *fl, struct pid_namespace *ns)
2273{
2274	pid_t vnr;
2275	struct pid *pid;
2276
2277	if (fl->flc_flags & FL_OFDLCK)
2278		return -1;
2279
2280	/* Remote locks report a negative pid value */
2281	if (fl->flc_pid <= 0)
2282		return fl->flc_pid;
2283
2284	/*
2285	 * If the flock owner process is dead and its pid has been already
2286	 * freed, the translation below won't work, but we still want to show
2287	 * flock owner pid number in init pidns.
2288	 */
2289	if (ns == &init_pid_ns)
2290		return (pid_t) fl->flc_pid;
2291
2292	rcu_read_lock();
2293	pid = find_pid_ns(fl->flc_pid, &init_pid_ns);
2294	vnr = pid_nr_ns(pid, ns);
2295	rcu_read_unlock();
2296	return vnr;
2297}
2298
2299static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
2300{
2301	flock->l_pid = locks_translate_pid(&fl->c, task_active_pid_ns(current));
2302#if BITS_PER_LONG == 32
2303	/*
2304	 * Make sure we can represent the posix lock via
2305	 * legacy 32bit flock.
2306	 */
2307	if (fl->fl_start > OFFT_OFFSET_MAX)
2308		return -EOVERFLOW;
2309	if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
2310		return -EOVERFLOW;
2311#endif
2312	flock->l_start = fl->fl_start;
2313	flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2314		fl->fl_end - fl->fl_start + 1;
2315	flock->l_whence = 0;
2316	flock->l_type = fl->c.flc_type;
2317	return 0;
2318}
2319
2320#if BITS_PER_LONG == 32
2321static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
2322{
2323	flock->l_pid = locks_translate_pid(&fl->c, task_active_pid_ns(current));
2324	flock->l_start = fl->fl_start;
2325	flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2326		fl->fl_end - fl->fl_start + 1;
2327	flock->l_whence = 0;
2328	flock->l_type = fl->c.flc_type;
2329}
2330#endif
2331
2332/* Report the first existing lock that would conflict with l.
2333 * This implements the F_GETLK command of fcntl().
2334 */
2335int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock *flock)
2336{
2337	struct file_lock *fl;
2338	int error;
2339
2340	fl = locks_alloc_lock();
2341	if (fl == NULL)
2342		return -ENOMEM;
2343	error = -EINVAL;
2344	if (cmd != F_OFD_GETLK && flock->l_type != F_RDLCK
2345			&& flock->l_type != F_WRLCK)
2346		goto out;
2347
2348	error = flock_to_posix_lock(filp, fl, flock);
2349	if (error)
2350		goto out;
2351
2352	if (cmd == F_OFD_GETLK) {
2353		error = -EINVAL;
2354		if (flock->l_pid != 0)
2355			goto out;
2356
2357		fl->c.flc_flags |= FL_OFDLCK;
2358		fl->c.flc_owner = filp;
2359	}
2360
2361	error = vfs_test_lock(filp, fl);
2362	if (error)
2363		goto out;
2364
2365	flock->l_type = fl->c.flc_type;
2366	if (fl->c.flc_type != F_UNLCK) {
2367		error = posix_lock_to_flock(flock, fl);
2368		if (error)
2369			goto out;
2370	}
2371out:
2372	locks_free_lock(fl);
2373	return error;
2374}
2375
2376/**
2377 * vfs_lock_file - file byte range lock
2378 * @filp: The file to apply the lock to
2379 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
2380 * @fl: The lock to be applied
2381 * @conf: Place to return a copy of the conflicting lock, if found.
2382 *
2383 * A caller that doesn't care about the conflicting lock may pass NULL
2384 * as the final argument.
2385 *
2386 * If the filesystem defines a private ->lock() method, then @conf will
2387 * be left unchanged; so a caller that cares should initialize it to
2388 * some acceptable default.
2389 *
2390 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
2391 * locks, the ->lock() interface may return asynchronously, before the lock has
2392 * been granted or denied by the underlying filesystem, if (and only if)
2393 * lm_grant is set. Additionally FOP_ASYNC_LOCK in file_operations fop_flags
2394 * need to be set.
2395 *
2396 * Callers expecting ->lock() to return asynchronously will only use F_SETLK,
2397 * not F_SETLKW; they will set FL_SLEEP if (and only if) the request is for a
2398 * blocking lock. When ->lock() does return asynchronously, it must return
2399 * FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock request completes.
2400 * If the request is for non-blocking lock the file system should return
2401 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
2402 * with the result. If the request timed out the callback routine will return a
2403 * nonzero return code and the file system should release the lock. The file
2404 * system is also responsible to keep a corresponding posix lock when it
2405 * grants a lock so the VFS can find out which locks are locally held and do
2406 * the correct lock cleanup when required.
2407 * The underlying filesystem must not drop the kernel lock or call
2408 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
2409 * return code.
2410 */
2411int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
2412{
2413	WARN_ON_ONCE(filp != fl->c.flc_file);
2414	if (filp->f_op->lock)
2415		return filp->f_op->lock(filp, cmd, fl);
2416	else
2417		return posix_lock_file(filp, fl, conf);
2418}
2419EXPORT_SYMBOL_GPL(vfs_lock_file);
2420
2421static int do_lock_file_wait(struct file *filp, unsigned int cmd,
2422			     struct file_lock *fl)
2423{
2424	int error;
2425
2426	error = security_file_lock(filp, fl->c.flc_type);
2427	if (error)
2428		return error;
2429
2430	for (;;) {
2431		error = vfs_lock_file(filp, cmd, fl, NULL);
2432		if (error != FILE_LOCK_DEFERRED)
2433			break;
2434		error = wait_event_interruptible(fl->c.flc_wait,
2435						 list_empty(&fl->c.flc_blocked_member));
2436		if (error)
2437			break;
2438	}
2439	locks_delete_block(fl);
2440
2441	return error;
2442}
2443
2444/* Ensure that fl->fl_file has compatible f_mode for F_SETLK calls */
2445static int
2446check_fmode_for_setlk(struct file_lock *fl)
2447{
2448	switch (fl->c.flc_type) {
2449	case F_RDLCK:
2450		if (!(fl->c.flc_file->f_mode & FMODE_READ))
2451			return -EBADF;
2452		break;
2453	case F_WRLCK:
2454		if (!(fl->c.flc_file->f_mode & FMODE_WRITE))
2455			return -EBADF;
2456	}
2457	return 0;
2458}
2459
2460/* Apply the lock described by l to an open file descriptor.
2461 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2462 */
2463int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
2464		struct flock *flock)
2465{
2466	struct file_lock *file_lock = locks_alloc_lock();
2467	struct inode *inode = file_inode(filp);
2468	struct file *f;
2469	int error;
2470
2471	if (file_lock == NULL)
2472		return -ENOLCK;
2473
2474	error = flock_to_posix_lock(filp, file_lock, flock);
2475	if (error)
2476		goto out;
2477
2478	error = check_fmode_for_setlk(file_lock);
2479	if (error)
2480		goto out;
2481
2482	/*
2483	 * If the cmd is requesting file-private locks, then set the
2484	 * FL_OFDLCK flag and override the owner.
2485	 */
2486	switch (cmd) {
2487	case F_OFD_SETLK:
2488		error = -EINVAL;
2489		if (flock->l_pid != 0)
2490			goto out;
2491
2492		cmd = F_SETLK;
2493		file_lock->c.flc_flags |= FL_OFDLCK;
2494		file_lock->c.flc_owner = filp;
2495		break;
2496	case F_OFD_SETLKW:
2497		error = -EINVAL;
2498		if (flock->l_pid != 0)
2499			goto out;
2500
2501		cmd = F_SETLKW;
2502		file_lock->c.flc_flags |= FL_OFDLCK;
2503		file_lock->c.flc_owner = filp;
2504		fallthrough;
2505	case F_SETLKW:
2506		file_lock->c.flc_flags |= FL_SLEEP;
2507	}
2508
2509	error = do_lock_file_wait(filp, cmd, file_lock);
2510
2511	/*
2512	 * Detect close/fcntl races and recover by zapping all POSIX locks
2513	 * associated with this file and our files_struct, just like on
2514	 * filp_flush(). There is no need to do that when we're
2515	 * unlocking though, or for OFD locks.
2516	 */
2517	if (!error && file_lock->c.flc_type != F_UNLCK &&
2518	    !(file_lock->c.flc_flags & FL_OFDLCK)) {
2519		struct files_struct *files = current->files;
2520		/*
2521		 * We need that spin_lock here - it prevents reordering between
2522		 * update of i_flctx->flc_posix and check for it done in
2523		 * close(). rcu_read_lock() wouldn't do.
2524		 */
2525		spin_lock(&files->file_lock);
2526		f = files_lookup_fd_locked(files, fd);
2527		spin_unlock(&files->file_lock);
2528		if (f != filp) {
2529			locks_remove_posix(filp, files);
2530			error = -EBADF;
2531		}
2532	}
2533out:
2534	trace_fcntl_setlk(inode, file_lock, error);
2535	locks_free_lock(file_lock);
2536	return error;
2537}
2538
2539#if BITS_PER_LONG == 32
2540/* Report the first existing lock that would conflict with l.
2541 * This implements the F_GETLK command of fcntl().
2542 */
2543int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 *flock)
2544{
2545	struct file_lock *fl;
2546	int error;
2547
2548	fl = locks_alloc_lock();
2549	if (fl == NULL)
2550		return -ENOMEM;
2551
2552	error = -EINVAL;
2553	if (cmd != F_OFD_GETLK && flock->l_type != F_RDLCK
2554			&& flock->l_type != F_WRLCK)
2555		goto out;
2556
2557	error = flock64_to_posix_lock(filp, fl, flock);
2558	if (error)
2559		goto out;
2560
2561	if (cmd == F_OFD_GETLK) {
2562		error = -EINVAL;
2563		if (flock->l_pid != 0)
2564			goto out;
2565
2566		fl->c.flc_flags |= FL_OFDLCK;
2567		fl->c.flc_owner = filp;
2568	}
2569
2570	error = vfs_test_lock(filp, fl);
2571	if (error)
2572		goto out;
2573
2574	flock->l_type = fl->c.flc_type;
2575	if (fl->c.flc_type != F_UNLCK)
2576		posix_lock_to_flock64(flock, fl);
2577
2578out:
2579	locks_free_lock(fl);
2580	return error;
2581}
2582
2583/* Apply the lock described by l to an open file descriptor.
2584 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2585 */
2586int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
2587		struct flock64 *flock)
2588{
2589	struct file_lock *file_lock = locks_alloc_lock();
2590	struct file *f;
2591	int error;
2592
2593	if (file_lock == NULL)
2594		return -ENOLCK;
2595
2596	error = flock64_to_posix_lock(filp, file_lock, flock);
2597	if (error)
2598		goto out;
2599
2600	error = check_fmode_for_setlk(file_lock);
2601	if (error)
2602		goto out;
2603
2604	/*
2605	 * If the cmd is requesting file-private locks, then set the
2606	 * FL_OFDLCK flag and override the owner.
2607	 */
2608	switch (cmd) {
2609	case F_OFD_SETLK:
2610		error = -EINVAL;
2611		if (flock->l_pid != 0)
2612			goto out;
2613
2614		cmd = F_SETLK64;
2615		file_lock->c.flc_flags |= FL_OFDLCK;
2616		file_lock->c.flc_owner = filp;
2617		break;
2618	case F_OFD_SETLKW:
2619		error = -EINVAL;
2620		if (flock->l_pid != 0)
2621			goto out;
2622
2623		cmd = F_SETLKW64;
2624		file_lock->c.flc_flags |= FL_OFDLCK;
2625		file_lock->c.flc_owner = filp;
2626		fallthrough;
2627	case F_SETLKW64:
2628		file_lock->c.flc_flags |= FL_SLEEP;
2629	}
2630
2631	error = do_lock_file_wait(filp, cmd, file_lock);
2632
2633	/*
2634	 * Detect close/fcntl races and recover by zapping all POSIX locks
2635	 * associated with this file and our files_struct, just like on
2636	 * filp_flush(). There is no need to do that when we're
2637	 * unlocking though, or for OFD locks.
2638	 */
2639	if (!error && file_lock->c.flc_type != F_UNLCK &&
2640	    !(file_lock->c.flc_flags & FL_OFDLCK)) {
2641		struct files_struct *files = current->files;
2642		/*
2643		 * We need that spin_lock here - it prevents reordering between
2644		 * update of i_flctx->flc_posix and check for it done in
2645		 * close(). rcu_read_lock() wouldn't do.
2646		 */
2647		spin_lock(&files->file_lock);
2648		f = files_lookup_fd_locked(files, fd);
2649		spin_unlock(&files->file_lock);
2650		if (f != filp) {
2651			locks_remove_posix(filp, files);
2652			error = -EBADF;
2653		}
2654	}
2655out:
2656	locks_free_lock(file_lock);
2657	return error;
2658}
2659#endif /* BITS_PER_LONG == 32 */
2660
2661/*
2662 * This function is called when the file is being removed
2663 * from the task's fd array.  POSIX locks belonging to this task
2664 * are deleted at this time.
2665 */
2666void locks_remove_posix(struct file *filp, fl_owner_t owner)
2667{
2668	int error;
2669	struct inode *inode = file_inode(filp);
2670	struct file_lock lock;
2671	struct file_lock_context *ctx;
2672
2673	/*
2674	 * If there are no locks held on this file, we don't need to call
2675	 * posix_lock_file().  Another process could be setting a lock on this
2676	 * file at the same time, but we wouldn't remove that lock anyway.
2677	 */
2678	ctx = locks_inode_context(inode);
2679	if (!ctx || list_empty(&ctx->flc_posix))
2680		return;
2681
2682	locks_init_lock(&lock);
2683	lock.c.flc_type = F_UNLCK;
2684	lock.c.flc_flags = FL_POSIX | FL_CLOSE;
2685	lock.fl_start = 0;
2686	lock.fl_end = OFFSET_MAX;
2687	lock.c.flc_owner = owner;
2688	lock.c.flc_pid = current->tgid;
2689	lock.c.flc_file = filp;
2690	lock.fl_ops = NULL;
2691	lock.fl_lmops = NULL;
2692
2693	error = vfs_lock_file(filp, F_SETLK, &lock, NULL);
2694
2695	if (lock.fl_ops && lock.fl_ops->fl_release_private)
2696		lock.fl_ops->fl_release_private(&lock);
2697	trace_locks_remove_posix(inode, &lock, error);
2698}
2699EXPORT_SYMBOL(locks_remove_posix);
2700
2701/* The i_flctx must be valid when calling into here */
2702static void
2703locks_remove_flock(struct file *filp, struct file_lock_context *flctx)
2704{
2705	struct file_lock fl;
2706	struct inode *inode = file_inode(filp);
2707
2708	if (list_empty(&flctx->flc_flock))
2709		return;
2710
2711	flock_make_lock(filp, &fl, F_UNLCK);
2712	fl.c.flc_flags |= FL_CLOSE;
2713
2714	if (filp->f_op->flock)
2715		filp->f_op->flock(filp, F_SETLKW, &fl);
2716	else
2717		flock_lock_inode(inode, &fl);
2718
2719	if (fl.fl_ops && fl.fl_ops->fl_release_private)
2720		fl.fl_ops->fl_release_private(&fl);
2721}
2722
2723/* The i_flctx must be valid when calling into here */
2724static void
2725locks_remove_lease(struct file *filp, struct file_lock_context *ctx)
2726{
2727	struct file_lease *fl, *tmp;
2728	LIST_HEAD(dispose);
2729
2730	if (list_empty(&ctx->flc_lease))
2731		return;
2732
2733	percpu_down_read(&file_rwsem);
2734	spin_lock(&ctx->flc_lock);
2735	list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, c.flc_list)
2736		if (filp == fl->c.flc_file)
2737			lease_modify(fl, F_UNLCK, &dispose);
2738	spin_unlock(&ctx->flc_lock);
2739	percpu_up_read(&file_rwsem);
2740
2741	lease_dispose_list(&dispose);
2742}
2743
2744/*
2745 * This function is called on the last close of an open file.
2746 */
2747void locks_remove_file(struct file *filp)
2748{
2749	struct file_lock_context *ctx;
2750
2751	ctx = locks_inode_context(file_inode(filp));
2752	if (!ctx)
2753		return;
2754
2755	/* remove any OFD locks */
2756	locks_remove_posix(filp, filp);
2757
2758	/* remove flock locks */
2759	locks_remove_flock(filp, ctx);
2760
2761	/* remove any leases */
2762	locks_remove_lease(filp, ctx);
2763
2764	spin_lock(&ctx->flc_lock);
2765	locks_check_ctx_file_list(filp, &ctx->flc_posix, "POSIX");
2766	locks_check_ctx_file_list(filp, &ctx->flc_flock, "FLOCK");
2767	locks_check_ctx_file_list(filp, &ctx->flc_lease, "LEASE");
2768	spin_unlock(&ctx->flc_lock);
2769}
2770
2771/**
2772 * vfs_cancel_lock - file byte range unblock lock
2773 * @filp: The file to apply the unblock to
2774 * @fl: The lock to be unblocked
2775 *
2776 * Used by lock managers to cancel blocked requests
2777 */
2778int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2779{
2780	WARN_ON_ONCE(filp != fl->c.flc_file);
2781	if (filp->f_op->lock)
2782		return filp->f_op->lock(filp, F_CANCELLK, fl);
2783	return 0;
2784}
2785EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2786
2787/**
2788 * vfs_inode_has_locks - are any file locks held on @inode?
2789 * @inode: inode to check for locks
2790 *
2791 * Return true if there are any FL_POSIX or FL_FLOCK locks currently
2792 * set on @inode.
2793 */
2794bool vfs_inode_has_locks(struct inode *inode)
2795{
2796	struct file_lock_context *ctx;
2797	bool ret;
2798
2799	ctx = locks_inode_context(inode);
2800	if (!ctx)
2801		return false;
2802
2803	spin_lock(&ctx->flc_lock);
2804	ret = !list_empty(&ctx->flc_posix) || !list_empty(&ctx->flc_flock);
2805	spin_unlock(&ctx->flc_lock);
2806	return ret;
2807}
2808EXPORT_SYMBOL_GPL(vfs_inode_has_locks);
2809
2810#ifdef CONFIG_PROC_FS
2811#include <linux/proc_fs.h>
2812#include <linux/seq_file.h>
2813
2814struct locks_iterator {
2815	int	li_cpu;
2816	loff_t	li_pos;
2817};
2818
2819static void lock_get_status(struct seq_file *f, struct file_lock_core *flc,
2820			    loff_t id, char *pfx, int repeat)
2821{
2822	struct inode *inode = NULL;
2823	unsigned int pid;
2824	struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);
2825	int type = flc->flc_type;
2826	struct file_lock *fl = file_lock(flc);
2827
2828	pid = locks_translate_pid(flc, proc_pidns);
2829
2830	/*
2831	 * If lock owner is dead (and pid is freed) or not visible in current
2832	 * pidns, zero is shown as a pid value. Check lock info from
2833	 * init_pid_ns to get saved lock pid value.
2834	 */
2835	if (flc->flc_file != NULL)
2836		inode = file_inode(flc->flc_file);
2837
2838	seq_printf(f, "%lld: ", id);
2839
2840	if (repeat)
2841		seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx);
2842
2843	if (flc->flc_flags & FL_POSIX) {
2844		if (flc->flc_flags & FL_ACCESS)
2845			seq_puts(f, "ACCESS");
2846		else if (flc->flc_flags & FL_OFDLCK)
2847			seq_puts(f, "OFDLCK");
2848		else
2849			seq_puts(f, "POSIX ");
2850
2851		seq_printf(f, " %s ",
2852			     (inode == NULL) ? "*NOINODE*" : "ADVISORY ");
2853	} else if (flc->flc_flags & FL_FLOCK) {
2854		seq_puts(f, "FLOCK  ADVISORY  ");
2855	} else if (flc->flc_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT)) {
2856		struct file_lease *lease = file_lease(flc);
2857
2858		type = target_leasetype(lease);
2859
2860		if (flc->flc_flags & FL_DELEG)
2861			seq_puts(f, "DELEG  ");
2862		else
2863			seq_puts(f, "LEASE  ");
2864
2865		if (lease_breaking(lease))
2866			seq_puts(f, "BREAKING  ");
2867		else if (flc->flc_file)
2868			seq_puts(f, "ACTIVE    ");
2869		else
2870			seq_puts(f, "BREAKER   ");
2871	} else {
2872		seq_puts(f, "UNKNOWN UNKNOWN  ");
2873	}
2874
2875	seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" :
2876			     (type == F_RDLCK) ? "READ" : "UNLCK");
2877	if (inode) {
2878		/* userspace relies on this representation of dev_t */
2879		seq_printf(f, "%d %02x:%02x:%lu ", pid,
2880				MAJOR(inode->i_sb->s_dev),
2881				MINOR(inode->i_sb->s_dev), inode->i_ino);
2882	} else {
2883		seq_printf(f, "%d <none>:0 ", pid);
2884	}
2885	if (flc->flc_flags & FL_POSIX) {
2886		if (fl->fl_end == OFFSET_MAX)
2887			seq_printf(f, "%Ld EOF\n", fl->fl_start);
2888		else
2889			seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2890	} else {
2891		seq_puts(f, "0 EOF\n");
2892	}
2893}
2894
2895static struct file_lock_core *get_next_blocked_member(struct file_lock_core *node)
2896{
2897	struct file_lock_core *tmp;
2898
2899	/* NULL node or root node */
2900	if (node == NULL || node->flc_blocker == NULL)
2901		return NULL;
2902
2903	/* Next member in the linked list could be itself */
2904	tmp = list_next_entry(node, flc_blocked_member);
2905	if (list_entry_is_head(tmp, &node->flc_blocker->flc_blocked_requests,
2906			       flc_blocked_member)
2907		|| tmp == node) {
2908		return NULL;
2909	}
2910
2911	return tmp;
2912}
2913
2914static int locks_show(struct seq_file *f, void *v)
2915{
2916	struct locks_iterator *iter = f->private;
2917	struct file_lock_core *cur, *tmp;
2918	struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);
2919	int level = 0;
2920
2921	cur = hlist_entry(v, struct file_lock_core, flc_link);
2922
2923	if (locks_translate_pid(cur, proc_pidns) == 0)
2924		return 0;
2925
2926	/* View this crossed linked list as a binary tree, the first member of flc_blocked_requests
2927	 * is the left child of current node, the next silibing in flc_blocked_member is the
2928	 * right child, we can alse get the parent of current node from flc_blocker, so this
2929	 * question becomes traversal of a binary tree
2930	 */
2931	while (cur != NULL) {
2932		if (level)
2933			lock_get_status(f, cur, iter->li_pos, "-> ", level);
2934		else
2935			lock_get_status(f, cur, iter->li_pos, "", level);
2936
2937		if (!list_empty(&cur->flc_blocked_requests)) {
2938			/* Turn left */
2939			cur = list_first_entry_or_null(&cur->flc_blocked_requests,
2940						       struct file_lock_core,
2941						       flc_blocked_member);
2942			level++;
2943		} else {
2944			/* Turn right */
2945			tmp = get_next_blocked_member(cur);
2946			/* Fall back to parent node */
2947			while (tmp == NULL && cur->flc_blocker != NULL) {
2948				cur = cur->flc_blocker;
2949				level--;
2950				tmp = get_next_blocked_member(cur);
2951			}
2952			cur = tmp;
2953		}
2954	}
2955
2956	return 0;
2957}
2958
2959static void __show_fd_locks(struct seq_file *f,
2960			struct list_head *head, int *id,
2961			struct file *filp, struct files_struct *files)
2962{
2963	struct file_lock_core *fl;
2964
2965	list_for_each_entry(fl, head, flc_list) {
2966
2967		if (filp != fl->flc_file)
2968			continue;
2969		if (fl->flc_owner != files && fl->flc_owner != filp)
2970			continue;
2971
2972		(*id)++;
2973		seq_puts(f, "lock:\t");
2974		lock_get_status(f, fl, *id, "", 0);
2975	}
2976}
2977
2978void show_fd_locks(struct seq_file *f,
2979		  struct file *filp, struct files_struct *files)
2980{
2981	struct inode *inode = file_inode(filp);
2982	struct file_lock_context *ctx;
2983	int id = 0;
2984
2985	ctx = locks_inode_context(inode);
2986	if (!ctx)
2987		return;
2988
2989	spin_lock(&ctx->flc_lock);
2990	__show_fd_locks(f, &ctx->flc_flock, &id, filp, files);
2991	__show_fd_locks(f, &ctx->flc_posix, &id, filp, files);
2992	__show_fd_locks(f, &ctx->flc_lease, &id, filp, files);
2993	spin_unlock(&ctx->flc_lock);
2994}
2995
2996static void *locks_start(struct seq_file *f, loff_t *pos)
2997	__acquires(&blocked_lock_lock)
2998{
2999	struct locks_iterator *iter = f->private;
3000
3001	iter->li_pos = *pos + 1;
3002	percpu_down_write(&file_rwsem);
3003	spin_lock(&blocked_lock_lock);
3004	return seq_hlist_start_percpu(&file_lock_list.hlist, &iter->li_cpu, *pos);
3005}
3006
3007static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
3008{
3009	struct locks_iterator *iter = f->private;
3010
3011	++iter->li_pos;
3012	return seq_hlist_next_percpu(v, &file_lock_list.hlist, &iter->li_cpu, pos);
3013}
3014
3015static void locks_stop(struct seq_file *f, void *v)
3016	__releases(&blocked_lock_lock)
3017{
3018	spin_unlock(&blocked_lock_lock);
3019	percpu_up_write(&file_rwsem);
3020}
3021
3022static const struct seq_operations locks_seq_operations = {
3023	.start	= locks_start,
3024	.next	= locks_next,
3025	.stop	= locks_stop,
3026	.show	= locks_show,
3027};
3028
3029static int __init proc_locks_init(void)
3030{
3031	proc_create_seq_private("locks", 0, NULL, &locks_seq_operations,
3032			sizeof(struct locks_iterator), NULL);
3033	return 0;
3034}
3035fs_initcall(proc_locks_init);
3036#endif
3037
3038static int __init filelock_init(void)
3039{
3040	int i;
3041
3042	flctx_cache = kmem_cache_create("file_lock_ctx",
3043			sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL);
3044
3045	filelock_cache = kmem_cache_create("file_lock_cache",
3046			sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
3047
3048	filelease_cache = kmem_cache_create("file_lease_cache",
3049			sizeof(struct file_lease), 0, SLAB_PANIC, NULL);
3050
3051	for_each_possible_cpu(i) {
3052		struct file_lock_list_struct *fll = per_cpu_ptr(&file_lock_list, i);
3053
3054		spin_lock_init(&fll->lock);
3055		INIT_HLIST_HEAD(&fll->hlist);
3056	}
3057
3058	lease_notifier_chain_init();
3059	return 0;
3060}
3061core_initcall(filelock_init);