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
  52#include <linux/capability.h>
  53#include <linux/file.h>
  54#include <linux/fdtable.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
  72#define IS_POSIX(fl)	(fl->fl_flags & FL_POSIX)
  73#define IS_FLOCK(fl)	(fl->fl_flags & FL_FLOCK)
  74#define IS_LEASE(fl)	(fl->fl_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT))
  75#define IS_OFDLCK(fl)	(fl->fl_flags & FL_OFDLCK)
  76#define IS_REMOTELCK(fl)	(fl->fl_pid <= 0)
  77
 
 
 
 
 
  78static bool lease_breaking(struct file_lock *fl)
  79{
  80	return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
  81}
  82
  83static int target_leasetype(struct file_lock *fl)
  84{
  85	if (fl->fl_flags & FL_UNLOCK_PENDING)
  86		return F_UNLCK;
  87	if (fl->fl_flags & FL_DOWNGRADE_PENDING)
  88		return F_RDLCK;
  89	return fl->fl_type;
  90}
  91
  92static int leases_enable = 1;
  93static int lease_break_time = 45;
  94
  95#ifdef CONFIG_SYSCTL
  96static struct ctl_table locks_sysctls[] = {
  97	{
  98		.procname	= "leases-enable",
  99		.data		= &leases_enable,
 100		.maxlen		= sizeof(int),
 101		.mode		= 0644,
 102		.proc_handler	= proc_dointvec,
 103	},
 104#ifdef CONFIG_MMU
 105	{
 106		.procname	= "lease-break-time",
 107		.data		= &lease_break_time,
 108		.maxlen		= sizeof(int),
 109		.mode		= 0644,
 110		.proc_handler	= proc_dointvec,
 111	},
 112#endif /* CONFIG_MMU */
 113	{}
 114};
 115
 116static int __init init_fs_locks_sysctls(void)
 117{
 118	register_sysctl_init("fs", locks_sysctls);
 119	return 0;
 120}
 121early_initcall(init_fs_locks_sysctls);
 122#endif /* CONFIG_SYSCTL */
 123
 124/*
 125 * The global file_lock_list is only used for displaying /proc/locks, so we
 126 * keep a list on each CPU, with each list protected by its own spinlock.
 127 * Global serialization is done using file_rwsem.
 128 *
 129 * Note that alterations to the list also require that the relevant flc_lock is
 130 * held.
 131 */
 132struct file_lock_list_struct {
 133	spinlock_t		lock;
 134	struct hlist_head	hlist;
 135};
 136static DEFINE_PER_CPU(struct file_lock_list_struct, file_lock_list);
 137DEFINE_STATIC_PERCPU_RWSEM(file_rwsem);
 138
 139
 140/*
 141 * The blocked_hash is used to find POSIX lock loops for deadlock detection.
 142 * It is protected by blocked_lock_lock.
 143 *
 144 * We hash locks by lockowner in order to optimize searching for the lock a
 145 * particular lockowner is waiting on.
 146 *
 147 * FIXME: make this value scale via some heuristic? We generally will want more
 148 * buckets when we have more lockowners holding locks, but that's a little
 149 * difficult to determine without knowing what the workload will look like.
 150 */
 151#define BLOCKED_HASH_BITS	7
 152static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
 153
 154/*
 155 * This lock protects the blocked_hash. Generally, if you're accessing it, you
 156 * want to be holding this lock.
 157 *
 158 * In addition, it also protects the fl->fl_blocked_requests list, and the
 159 * fl->fl_blocker pointer for file_lock structures that are acting as lock
 160 * requests (in contrast to those that are acting as records of acquired locks).
 161 *
 162 * Note that when we acquire this lock in order to change the above fields,
 163 * we often hold the flc_lock as well. In certain cases, when reading the fields
 164 * protected by this lock, we can skip acquiring it iff we already hold the
 165 * flc_lock.
 
 
 
 
 166 */
 167static DEFINE_SPINLOCK(blocked_lock_lock);
 168
 169static struct kmem_cache *flctx_cache __read_mostly;
 170static struct kmem_cache *filelock_cache __read_mostly;
 171
 172static struct file_lock_context *
 173locks_get_lock_context(struct inode *inode, int type)
 174{
 175	struct file_lock_context *ctx;
 176
 177	/* paired with cmpxchg() below */
 178	ctx = locks_inode_context(inode);
 179	if (likely(ctx) || type == F_UNLCK)
 180		goto out;
 181
 182	ctx = kmem_cache_alloc(flctx_cache, GFP_KERNEL);
 183	if (!ctx)
 184		goto out;
 185
 186	spin_lock_init(&ctx->flc_lock);
 187	INIT_LIST_HEAD(&ctx->flc_flock);
 188	INIT_LIST_HEAD(&ctx->flc_posix);
 189	INIT_LIST_HEAD(&ctx->flc_lease);
 190
 191	/*
 192	 * Assign the pointer if it's not already assigned. If it is, then
 193	 * free the context we just allocated.
 194	 */
 195	if (cmpxchg(&inode->i_flctx, NULL, ctx)) {
 196		kmem_cache_free(flctx_cache, ctx);
 197		ctx = locks_inode_context(inode);
 198	}
 199out:
 200	trace_locks_get_lock_context(inode, type, ctx);
 201	return ctx;
 202}
 203
 204static void
 205locks_dump_ctx_list(struct list_head *list, char *list_type)
 206{
 207	struct file_lock *fl;
 208
 209	list_for_each_entry(fl, list, fl_list) {
 210		pr_warn("%s: fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n", list_type, fl->fl_owner, fl->fl_flags, fl->fl_type, fl->fl_pid);
 211	}
 212}
 213
 214static void
 215locks_check_ctx_lists(struct inode *inode)
 216{
 217	struct file_lock_context *ctx = inode->i_flctx;
 218
 219	if (unlikely(!list_empty(&ctx->flc_flock) ||
 220		     !list_empty(&ctx->flc_posix) ||
 221		     !list_empty(&ctx->flc_lease))) {
 222		pr_warn("Leaked locks on dev=0x%x:0x%x ino=0x%lx:\n",
 223			MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev),
 224			inode->i_ino);
 225		locks_dump_ctx_list(&ctx->flc_flock, "FLOCK");
 226		locks_dump_ctx_list(&ctx->flc_posix, "POSIX");
 227		locks_dump_ctx_list(&ctx->flc_lease, "LEASE");
 228	}
 229}
 230
 231static void
 232locks_check_ctx_file_list(struct file *filp, struct list_head *list,
 233				char *list_type)
 234{
 235	struct file_lock *fl;
 236	struct inode *inode = locks_inode(filp);
 237
 238	list_for_each_entry(fl, list, fl_list)
 239		if (fl->fl_file == filp)
 240			pr_warn("Leaked %s lock on dev=0x%x:0x%x ino=0x%lx "
 241				" fl_owner=%p fl_flags=0x%x fl_type=0x%x fl_pid=%u\n",
 242				list_type, MAJOR(inode->i_sb->s_dev),
 243				MINOR(inode->i_sb->s_dev), inode->i_ino,
 244				fl->fl_owner, fl->fl_flags, fl->fl_type, fl->fl_pid);
 245}
 246
 247void
 248locks_free_lock_context(struct inode *inode)
 249{
 250	struct file_lock_context *ctx = locks_inode_context(inode);
 251
 252	if (unlikely(ctx)) {
 253		locks_check_ctx_lists(inode);
 254		kmem_cache_free(flctx_cache, ctx);
 255	}
 256}
 257
 258static void locks_init_lock_heads(struct file_lock *fl)
 259{
 260	INIT_HLIST_NODE(&fl->fl_link);
 261	INIT_LIST_HEAD(&fl->fl_list);
 262	INIT_LIST_HEAD(&fl->fl_blocked_requests);
 263	INIT_LIST_HEAD(&fl->fl_blocked_member);
 264	init_waitqueue_head(&fl->fl_wait);
 265}
 266
 267/* Allocate an empty lock structure. */
 268struct file_lock *locks_alloc_lock(void)
 269{
 270	struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
 271
 272	if (fl)
 273		locks_init_lock_heads(fl);
 274
 275	return fl;
 276}
 277EXPORT_SYMBOL_GPL(locks_alloc_lock);
 278
 279void locks_release_private(struct file_lock *fl)
 280{
 281	BUG_ON(waitqueue_active(&fl->fl_wait));
 282	BUG_ON(!list_empty(&fl->fl_list));
 283	BUG_ON(!list_empty(&fl->fl_blocked_requests));
 284	BUG_ON(!list_empty(&fl->fl_blocked_member));
 285	BUG_ON(!hlist_unhashed(&fl->fl_link));
 286
 287	if (fl->fl_ops) {
 288		if (fl->fl_ops->fl_release_private)
 289			fl->fl_ops->fl_release_private(fl);
 290		fl->fl_ops = NULL;
 291	}
 292
 293	if (fl->fl_lmops) {
 294		if (fl->fl_lmops->lm_put_owner) {
 295			fl->fl_lmops->lm_put_owner(fl->fl_owner);
 296			fl->fl_owner = NULL;
 297		}
 298		fl->fl_lmops = NULL;
 299	}
 300}
 301EXPORT_SYMBOL_GPL(locks_release_private);
 302
 303/**
 304 * locks_owner_has_blockers - Check for blocking lock requests
 305 * @flctx: file lock context
 306 * @owner: lock owner
 307 *
 308 * Return values:
 309 *   %true: @owner has at least one blocker
 310 *   %false: @owner has no blockers
 311 */
 312bool locks_owner_has_blockers(struct file_lock_context *flctx,
 313		fl_owner_t owner)
 314{
 315	struct file_lock *fl;
 316
 317	spin_lock(&flctx->flc_lock);
 318	list_for_each_entry(fl, &flctx->flc_posix, fl_list) {
 319		if (fl->fl_owner != owner)
 320			continue;
 321		if (!list_empty(&fl->fl_blocked_requests)) {
 322			spin_unlock(&flctx->flc_lock);
 323			return true;
 324		}
 325	}
 326	spin_unlock(&flctx->flc_lock);
 327	return false;
 328}
 329EXPORT_SYMBOL_GPL(locks_owner_has_blockers);
 330
 331/* Free a lock which is not in use. */
 332void locks_free_lock(struct file_lock *fl)
 333{
 
 
 
 
 
 334	locks_release_private(fl);
 335	kmem_cache_free(filelock_cache, fl);
 336}
 337EXPORT_SYMBOL(locks_free_lock);
 338
 339static void
 340locks_dispose_list(struct list_head *dispose)
 341{
 342	struct file_lock *fl;
 343
 344	while (!list_empty(dispose)) {
 345		fl = list_first_entry(dispose, struct file_lock, fl_list);
 346		list_del_init(&fl->fl_list);
 347		locks_free_lock(fl);
 348	}
 349}
 350
 351void locks_init_lock(struct file_lock *fl)
 352{
 353	memset(fl, 0, sizeof(struct file_lock));
 354	locks_init_lock_heads(fl);
 355}
 
 356EXPORT_SYMBOL(locks_init_lock);
 357
 358/*
 359 * Initialize a new lock from an existing file_lock structure.
 360 */
 361void locks_copy_conflock(struct file_lock *new, struct file_lock *fl)
 362{
 363	new->fl_owner = fl->fl_owner;
 364	new->fl_pid = fl->fl_pid;
 365	new->fl_file = NULL;
 366	new->fl_flags = fl->fl_flags;
 367	new->fl_type = fl->fl_type;
 368	new->fl_start = fl->fl_start;
 369	new->fl_end = fl->fl_end;
 370	new->fl_lmops = fl->fl_lmops;
 371	new->fl_ops = NULL;
 372
 373	if (fl->fl_lmops) {
 374		if (fl->fl_lmops->lm_get_owner)
 375			fl->fl_lmops->lm_get_owner(fl->fl_owner);
 376	}
 377}
 378EXPORT_SYMBOL(locks_copy_conflock);
 379
 380void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 381{
 382	/* "new" must be a freshly-initialized lock */
 383	WARN_ON_ONCE(new->fl_ops);
 384
 385	locks_copy_conflock(new, fl);
 386
 387	new->fl_file = fl->fl_file;
 388	new->fl_ops = fl->fl_ops;
 389
 390	if (fl->fl_ops) {
 391		if (fl->fl_ops->fl_copy_lock)
 392			fl->fl_ops->fl_copy_lock(new, fl);
 393	}
 394}
 395EXPORT_SYMBOL(locks_copy_lock);
 396
 397static void locks_move_blocks(struct file_lock *new, struct file_lock *fl)
 398{
 399	struct file_lock *f;
 400
 401	/*
 402	 * As ctx->flc_lock is held, new requests cannot be added to
 403	 * ->fl_blocked_requests, so we don't need a lock to check if it
 404	 * is empty.
 405	 */
 406	if (list_empty(&fl->fl_blocked_requests))
 407		return;
 408	spin_lock(&blocked_lock_lock);
 409	list_splice_init(&fl->fl_blocked_requests, &new->fl_blocked_requests);
 410	list_for_each_entry(f, &new->fl_blocked_requests, fl_blocked_member)
 411		f->fl_blocker = new;
 412	spin_unlock(&blocked_lock_lock);
 413}
 414
 415static inline int flock_translate_cmd(int cmd) {
 
 
 416	switch (cmd) {
 417	case LOCK_SH:
 418		return F_RDLCK;
 419	case LOCK_EX:
 420		return F_WRLCK;
 421	case LOCK_UN:
 422		return F_UNLCK;
 423	}
 424	return -EINVAL;
 425}
 426
 427/* Fill in a file_lock structure with an appropriate FLOCK lock. */
 428static void flock_make_lock(struct file *filp, struct file_lock *fl, int type)
 
 429{
 430	locks_init_lock(fl);
 
 
 
 
 
 
 
 
 431
 432	fl->fl_file = filp;
 433	fl->fl_owner = filp;
 434	fl->fl_pid = current->tgid;
 435	fl->fl_flags = FL_FLOCK;
 436	fl->fl_type = type;
 437	fl->fl_end = OFFSET_MAX;
 
 
 438}
 439
 440static int assign_type(struct file_lock *fl, long type)
 441{
 442	switch (type) {
 443	case F_RDLCK:
 444	case F_WRLCK:
 445	case F_UNLCK:
 446		fl->fl_type = type;
 447		break;
 448	default:
 449		return -EINVAL;
 450	}
 451	return 0;
 452}
 453
 454static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
 455				 struct flock64 *l)
 456{
 457	switch (l->l_whence) {
 458	case SEEK_SET:
 459		fl->fl_start = 0;
 460		break;
 461	case SEEK_CUR:
 462		fl->fl_start = filp->f_pos;
 463		break;
 464	case SEEK_END:
 465		fl->fl_start = i_size_read(file_inode(filp));
 466		break;
 467	default:
 468		return -EINVAL;
 469	}
 470	if (l->l_start > OFFSET_MAX - fl->fl_start)
 471		return -EOVERFLOW;
 472	fl->fl_start += l->l_start;
 473	if (fl->fl_start < 0)
 474		return -EINVAL;
 475
 476	/* POSIX-1996 leaves the case l->l_len < 0 undefined;
 477	   POSIX-2001 defines it. */
 478	if (l->l_len > 0) {
 479		if (l->l_len - 1 > OFFSET_MAX - fl->fl_start)
 480			return -EOVERFLOW;
 481		fl->fl_end = fl->fl_start + (l->l_len - 1);
 482
 483	} else if (l->l_len < 0) {
 484		if (fl->fl_start + l->l_len < 0)
 485			return -EINVAL;
 486		fl->fl_end = fl->fl_start - 1;
 487		fl->fl_start += l->l_len;
 488	} else
 489		fl->fl_end = OFFSET_MAX;
 490
 491	fl->fl_owner = current->files;
 492	fl->fl_pid = current->tgid;
 493	fl->fl_file = filp;
 494	fl->fl_flags = FL_POSIX;
 495	fl->fl_ops = NULL;
 496	fl->fl_lmops = NULL;
 497
 498	return assign_type(fl, l->l_type);
 499}
 500
 501/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
 502 * style lock.
 503 */
 504static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
 505			       struct flock *l)
 506{
 507	struct flock64 ll = {
 508		.l_type = l->l_type,
 509		.l_whence = l->l_whence,
 510		.l_start = l->l_start,
 511		.l_len = l->l_len,
 512	};
 513
 514	return flock64_to_posix_lock(filp, fl, &ll);
 515}
 516
 517/* default lease lock manager operations */
 518static bool
 519lease_break_callback(struct file_lock *fl)
 520{
 521	kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
 522	return false;
 523}
 524
 525static void
 526lease_setup(struct file_lock *fl, void **priv)
 527{
 528	struct file *filp = fl->fl_file;
 529	struct fasync_struct *fa = *priv;
 530
 531	/*
 532	 * fasync_insert_entry() returns the old entry if any. If there was no
 533	 * old entry, then it used "priv" and inserted it into the fasync list.
 534	 * Clear the pointer to indicate that it shouldn't be freed.
 535	 */
 536	if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa))
 537		*priv = NULL;
 538
 539	__f_setown(filp, task_pid(current), PIDTYPE_TGID, 0);
 540}
 541
 542static const struct lock_manager_operations lease_manager_ops = {
 543	.lm_break = lease_break_callback,
 544	.lm_change = lease_modify,
 545	.lm_setup = lease_setup,
 546};
 547
 548/*
 549 * Initialize a lease, use the default lock manager operations
 550 */
 551static int lease_init(struct file *filp, long type, struct file_lock *fl)
 552{
 553	if (assign_type(fl, type) != 0)
 554		return -EINVAL;
 555
 556	fl->fl_owner = filp;
 557	fl->fl_pid = current->tgid;
 558
 559	fl->fl_file = filp;
 560	fl->fl_flags = FL_LEASE;
 561	fl->fl_start = 0;
 562	fl->fl_end = OFFSET_MAX;
 563	fl->fl_ops = NULL;
 564	fl->fl_lmops = &lease_manager_ops;
 565	return 0;
 566}
 567
 568/* Allocate a file_lock initialised to this type of lease */
 569static struct file_lock *lease_alloc(struct file *filp, long type)
 570{
 571	struct file_lock *fl = locks_alloc_lock();
 572	int error = -ENOMEM;
 573
 574	if (fl == NULL)
 575		return ERR_PTR(error);
 576
 577	error = lease_init(filp, type, fl);
 578	if (error) {
 579		locks_free_lock(fl);
 580		return ERR_PTR(error);
 581	}
 582	return fl;
 583}
 584
 585/* Check if two locks overlap each other.
 586 */
 587static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
 588{
 589	return ((fl1->fl_end >= fl2->fl_start) &&
 590		(fl2->fl_end >= fl1->fl_start));
 591}
 592
 593/*
 594 * Check whether two locks have the same owner.
 595 */
 596static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 597{
 
 
 
 598	return fl1->fl_owner == fl2->fl_owner;
 599}
 600
 601/* Must be called with the flc_lock held! */
 602static void locks_insert_global_locks(struct file_lock *fl)
 603{
 604	struct file_lock_list_struct *fll = this_cpu_ptr(&file_lock_list);
 605
 606	percpu_rwsem_assert_held(&file_rwsem);
 607
 608	spin_lock(&fll->lock);
 609	fl->fl_link_cpu = smp_processor_id();
 610	hlist_add_head(&fl->fl_link, &fll->hlist);
 611	spin_unlock(&fll->lock);
 612}
 613
 614/* Must be called with the flc_lock held! */
 615static void locks_delete_global_locks(struct file_lock *fl)
 616{
 617	struct file_lock_list_struct *fll;
 618
 619	percpu_rwsem_assert_held(&file_rwsem);
 620
 621	/*
 622	 * Avoid taking lock if already unhashed. This is safe since this check
 623	 * is done while holding the flc_lock, and new insertions into the list
 624	 * also require that it be held.
 625	 */
 626	if (hlist_unhashed(&fl->fl_link))
 627		return;
 628
 629	fll = per_cpu_ptr(&file_lock_list, fl->fl_link_cpu);
 630	spin_lock(&fll->lock);
 631	hlist_del_init(&fl->fl_link);
 632	spin_unlock(&fll->lock);
 633}
 634
 635static unsigned long
 636posix_owner_key(struct file_lock *fl)
 637{
 
 
 638	return (unsigned long)fl->fl_owner;
 639}
 640
 641static void locks_insert_global_blocked(struct file_lock *waiter)
 642{
 643	lockdep_assert_held(&blocked_lock_lock);
 644
 645	hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter));
 646}
 647
 648static void locks_delete_global_blocked(struct file_lock *waiter)
 649{
 650	lockdep_assert_held(&blocked_lock_lock);
 651
 652	hash_del(&waiter->fl_link);
 653}
 654
 655/* Remove waiter from blocker's block list.
 656 * When blocker ends up pointing to itself then the list is empty.
 657 *
 658 * Must be called with blocked_lock_lock held.
 659 */
 660static void __locks_delete_block(struct file_lock *waiter)
 661{
 662	locks_delete_global_blocked(waiter);
 663	list_del_init(&waiter->fl_blocked_member);
 
 664}
 665
 666static void __locks_wake_up_blocks(struct file_lock *blocker)
 667{
 668	while (!list_empty(&blocker->fl_blocked_requests)) {
 669		struct file_lock *waiter;
 670
 671		waiter = list_first_entry(&blocker->fl_blocked_requests,
 672					  struct file_lock, fl_blocked_member);
 673		__locks_delete_block(waiter);
 674		if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
 675			waiter->fl_lmops->lm_notify(waiter);
 676		else
 677			wake_up(&waiter->fl_wait);
 678
 679		/*
 680		 * The setting of fl_blocker to NULL marks the "done"
 681		 * point in deleting a block. Paired with acquire at the top
 682		 * of locks_delete_block().
 683		 */
 684		smp_store_release(&waiter->fl_blocker, NULL);
 685	}
 686}
 687
 688/**
 689 *	locks_delete_block - stop waiting for a file lock
 690 *	@waiter: the lock which was waiting
 691 *
 692 *	lockd/nfsd need to disconnect the lock while working on it.
 693 */
 694int locks_delete_block(struct file_lock *waiter)
 695{
 696	int status = -ENOENT;
 697
 698	/*
 699	 * If fl_blocker is NULL, it won't be set again as this thread "owns"
 700	 * the lock and is the only one that might try to claim the lock.
 701	 *
 702	 * We use acquire/release to manage fl_blocker so that we can
 703	 * optimize away taking the blocked_lock_lock in many cases.
 704	 *
 705	 * The smp_load_acquire guarantees two things:
 706	 *
 707	 * 1/ that fl_blocked_requests can be tested locklessly. If something
 708	 * was recently added to that list it must have been in a locked region
 709	 * *before* the locked region when fl_blocker was set to NULL.
 710	 *
 711	 * 2/ that no other thread is accessing 'waiter', so it is safe to free
 712	 * it.  __locks_wake_up_blocks is careful not to touch waiter after
 713	 * fl_blocker is released.
 714	 *
 715	 * If a lockless check of fl_blocker shows it to be NULL, we know that
 716	 * no new locks can be inserted into its fl_blocked_requests list, and
 717	 * can avoid doing anything further if the list is empty.
 718	 */
 719	if (!smp_load_acquire(&waiter->fl_blocker) &&
 720	    list_empty(&waiter->fl_blocked_requests))
 721		return status;
 722
 723	spin_lock(&blocked_lock_lock);
 724	if (waiter->fl_blocker)
 725		status = 0;
 726	__locks_wake_up_blocks(waiter);
 727	__locks_delete_block(waiter);
 728
 729	/*
 730	 * The setting of fl_blocker to NULL marks the "done" point in deleting
 731	 * a block. Paired with acquire at the top of this function.
 732	 */
 733	smp_store_release(&waiter->fl_blocker, NULL);
 734	spin_unlock(&blocked_lock_lock);
 735	return status;
 736}
 737EXPORT_SYMBOL(locks_delete_block);
 738
 739/* Insert waiter into blocker's block list.
 740 * We use a circular list so that processes can be easily woken up in
 741 * the order they blocked. The documentation doesn't require this but
 742 * it seems like the reasonable thing to do.
 743 *
 744 * Must be called with both the flc_lock and blocked_lock_lock held. The
 745 * fl_blocked_requests list itself is protected by the blocked_lock_lock,
 746 * but by ensuring that the flc_lock is also held on insertions we can avoid
 747 * taking the blocked_lock_lock in some cases when we see that the
 748 * fl_blocked_requests list is empty.
 749 *
 750 * Rather than just adding to the list, we check for conflicts with any existing
 751 * waiters, and add beneath any waiter that blocks the new waiter.
 752 * Thus wakeups don't happen until needed.
 753 */
 754static void __locks_insert_block(struct file_lock *blocker,
 755				 struct file_lock *waiter,
 756				 bool conflict(struct file_lock *,
 757					       struct file_lock *))
 758{
 759	struct file_lock *fl;
 760	BUG_ON(!list_empty(&waiter->fl_blocked_member));
 761
 762new_blocker:
 763	list_for_each_entry(fl, &blocker->fl_blocked_requests, fl_blocked_member)
 764		if (conflict(fl, waiter)) {
 765			blocker =  fl;
 766			goto new_blocker;
 767		}
 768	waiter->fl_blocker = blocker;
 769	list_add_tail(&waiter->fl_blocked_member, &blocker->fl_blocked_requests);
 770	if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))
 771		locks_insert_global_blocked(waiter);
 772
 773	/* The requests in waiter->fl_blocked are known to conflict with
 774	 * waiter, but might not conflict with blocker, or the requests
 775	 * and lock which block it.  So they all need to be woken.
 776	 */
 777	__locks_wake_up_blocks(waiter);
 778}
 779
 780/* Must be called with flc_lock held. */
 781static void locks_insert_block(struct file_lock *blocker,
 782			       struct file_lock *waiter,
 783			       bool conflict(struct file_lock *,
 784					     struct file_lock *))
 785{
 786	spin_lock(&blocked_lock_lock);
 787	__locks_insert_block(blocker, waiter, conflict);
 788	spin_unlock(&blocked_lock_lock);
 789}
 790
 791/*
 792 * Wake up processes blocked waiting for blocker.
 793 *
 794 * Must be called with the inode->flc_lock held!
 795 */
 796static void locks_wake_up_blocks(struct file_lock *blocker)
 797{
 798	/*
 799	 * Avoid taking global lock if list is empty. This is safe since new
 800	 * blocked requests are only added to the list under the flc_lock, and
 801	 * the flc_lock is always held here. Note that removal from the
 802	 * fl_blocked_requests list does not require the flc_lock, so we must
 803	 * recheck list_empty() after acquiring the blocked_lock_lock.
 804	 */
 805	if (list_empty(&blocker->fl_blocked_requests))
 806		return;
 807
 808	spin_lock(&blocked_lock_lock);
 809	__locks_wake_up_blocks(blocker);
 
 
 
 
 
 
 
 
 
 
 810	spin_unlock(&blocked_lock_lock);
 811}
 812
 813static void
 814locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before)
 815{
 816	list_add_tail(&fl->fl_list, before);
 817	locks_insert_global_locks(fl);
 818}
 819
 820static void
 821locks_unlink_lock_ctx(struct file_lock *fl)
 822{
 823	locks_delete_global_locks(fl);
 824	list_del_init(&fl->fl_list);
 825	locks_wake_up_blocks(fl);
 826}
 827
 828static void
 829locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose)
 830{
 831	locks_unlink_lock_ctx(fl);
 832	if (dispose)
 833		list_add(&fl->fl_list, dispose);
 834	else
 835		locks_free_lock(fl);
 836}
 837
 838/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
 839 * checks for shared/exclusive status of overlapping locks.
 840 */
 841static bool locks_conflict(struct file_lock *caller_fl,
 842			   struct file_lock *sys_fl)
 843{
 844	if (sys_fl->fl_type == F_WRLCK)
 845		return true;
 846	if (caller_fl->fl_type == F_WRLCK)
 847		return true;
 848	return false;
 849}
 850
 851/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
 852 * checking before calling the locks_conflict().
 853 */
 854static bool posix_locks_conflict(struct file_lock *caller_fl,
 855				 struct file_lock *sys_fl)
 856{
 857	/* POSIX locks owned by the same process do not conflict with
 858	 * each other.
 859	 */
 860	if (posix_same_owner(caller_fl, sys_fl))
 861		return false;
 862
 863	/* Check whether they overlap */
 864	if (!locks_overlap(caller_fl, sys_fl))
 865		return false;
 866
 867	return locks_conflict(caller_fl, sys_fl);
 868}
 869
 870/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
 871 * checking before calling the locks_conflict().
 872 */
 873static bool flock_locks_conflict(struct file_lock *caller_fl,
 874				 struct file_lock *sys_fl)
 875{
 876	/* FLOCK locks referring to the same filp do not conflict with
 877	 * each other.
 878	 */
 879	if (caller_fl->fl_file == sys_fl->fl_file)
 880		return false;
 
 
 881
 882	return locks_conflict(caller_fl, sys_fl);
 883}
 884
 885void
 886posix_test_lock(struct file *filp, struct file_lock *fl)
 887{
 888	struct file_lock *cfl;
 889	struct file_lock_context *ctx;
 890	struct inode *inode = locks_inode(filp);
 891	void *owner;
 892	void (*func)(void);
 893
 894	ctx = locks_inode_context(inode);
 895	if (!ctx || list_empty_careful(&ctx->flc_posix)) {
 896		fl->fl_type = F_UNLCK;
 897		return;
 898	}
 899
 900retry:
 901	spin_lock(&ctx->flc_lock);
 902	list_for_each_entry(cfl, &ctx->flc_posix, fl_list) {
 903		if (!posix_locks_conflict(fl, cfl))
 904			continue;
 905		if (cfl->fl_lmops && cfl->fl_lmops->lm_lock_expirable
 906			&& (*cfl->fl_lmops->lm_lock_expirable)(cfl)) {
 907			owner = cfl->fl_lmops->lm_mod_owner;
 908			func = cfl->fl_lmops->lm_expire_lock;
 909			__module_get(owner);
 910			spin_unlock(&ctx->flc_lock);
 911			(*func)();
 912			module_put(owner);
 913			goto retry;
 914		}
 915		locks_copy_conflock(fl, cfl);
 916		goto out;
 917	}
 918	fl->fl_type = F_UNLCK;
 919out:
 920	spin_unlock(&ctx->flc_lock);
 921	return;
 922}
 923EXPORT_SYMBOL(posix_test_lock);
 924
 925/*
 926 * Deadlock detection:
 927 *
 928 * We attempt to detect deadlocks that are due purely to posix file
 929 * locks.
 930 *
 931 * We assume that a task can be waiting for at most one lock at a time.
 932 * So for any acquired lock, the process holding that lock may be
 933 * waiting on at most one other lock.  That lock in turns may be held by
 934 * someone waiting for at most one other lock.  Given a requested lock
 935 * caller_fl which is about to wait for a conflicting lock block_fl, we
 936 * follow this chain of waiters to ensure we are not about to create a
 937 * cycle.
 938 *
 939 * Since we do this before we ever put a process to sleep on a lock, we
 940 * are ensured that there is never a cycle; that is what guarantees that
 941 * the while() loop in posix_locks_deadlock() eventually completes.
 942 *
 943 * Note: the above assumption may not be true when handling lock
 944 * requests from a broken NFS client. It may also fail in the presence
 945 * of tasks (such as posix threads) sharing the same open file table.
 946 * To handle those cases, we just bail out after a few iterations.
 947 *
 948 * For FL_OFDLCK locks, the owner is the filp, not the files_struct.
 949 * Because the owner is not even nominally tied to a thread of
 950 * execution, the deadlock detection below can't reasonably work well. Just
 951 * skip it for those.
 952 *
 953 * In principle, we could do a more limited deadlock detection on FL_OFDLCK
 954 * locks that just checks for the case where two tasks are attempting to
 955 * upgrade from read to write locks on the same inode.
 956 */
 957
 958#define MAX_DEADLK_ITERATIONS 10
 959
 960/* Find a lock that the owner of the given block_fl is blocking on. */
 961static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
 962{
 963	struct file_lock *fl;
 964
 965	hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) {
 966		if (posix_same_owner(fl, block_fl)) {
 967			while (fl->fl_blocker)
 968				fl = fl->fl_blocker;
 969			return fl;
 970		}
 971	}
 972	return NULL;
 973}
 974
 975/* Must be called with the blocked_lock_lock held! */
 976static int posix_locks_deadlock(struct file_lock *caller_fl,
 977				struct file_lock *block_fl)
 978{
 979	int i = 0;
 980
 981	lockdep_assert_held(&blocked_lock_lock);
 982
 983	/*
 984	 * This deadlock detector can't reasonably detect deadlocks with
 985	 * FL_OFDLCK locks, since they aren't owned by a process, per-se.
 986	 */
 987	if (IS_OFDLCK(caller_fl))
 988		return 0;
 989
 990	while ((block_fl = what_owner_is_waiting_for(block_fl))) {
 991		if (i++ > MAX_DEADLK_ITERATIONS)
 992			return 0;
 993		if (posix_same_owner(caller_fl, block_fl))
 994			return 1;
 995	}
 996	return 0;
 997}
 998
 999/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
1000 * after any leases, but before any posix locks.
1001 *
1002 * Note that if called with an FL_EXISTS argument, the caller may determine
1003 * whether or not a lock was successfully freed by testing the return
1004 * value for -ENOENT.
1005 */
1006static int flock_lock_inode(struct inode *inode, struct file_lock *request)
1007{
1008	struct file_lock *new_fl = NULL;
1009	struct file_lock *fl;
1010	struct file_lock_context *ctx;
1011	int error = 0;
1012	bool found = false;
1013	LIST_HEAD(dispose);
1014
1015	ctx = locks_get_lock_context(inode, request->fl_type);
1016	if (!ctx) {
1017		if (request->fl_type != F_UNLCK)
1018			return -ENOMEM;
1019		return (request->fl_flags & FL_EXISTS) ? -ENOENT : 0;
1020	}
1021
1022	if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
1023		new_fl = locks_alloc_lock();
1024		if (!new_fl)
1025			return -ENOMEM;
1026	}
1027
1028	percpu_down_read(&file_rwsem);
1029	spin_lock(&ctx->flc_lock);
1030	if (request->fl_flags & FL_ACCESS)
1031		goto find_conflict;
1032
1033	list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
1034		if (request->fl_file != fl->fl_file)
1035			continue;
1036		if (request->fl_type == fl->fl_type)
1037			goto out;
1038		found = true;
1039		locks_delete_lock_ctx(fl, &dispose);
1040		break;
1041	}
1042
1043	if (request->fl_type == F_UNLCK) {
1044		if ((request->fl_flags & FL_EXISTS) && !found)
1045			error = -ENOENT;
1046		goto out;
1047	}
1048
1049find_conflict:
1050	list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
1051		if (!flock_locks_conflict(request, fl))
1052			continue;
1053		error = -EAGAIN;
1054		if (!(request->fl_flags & FL_SLEEP))
1055			goto out;
1056		error = FILE_LOCK_DEFERRED;
1057		locks_insert_block(fl, request, flock_locks_conflict);
1058		goto out;
1059	}
1060	if (request->fl_flags & FL_ACCESS)
1061		goto out;
1062	locks_copy_lock(new_fl, request);
1063	locks_move_blocks(new_fl, request);
1064	locks_insert_lock_ctx(new_fl, &ctx->flc_flock);
1065	new_fl = NULL;
1066	error = 0;
1067
1068out:
1069	spin_unlock(&ctx->flc_lock);
1070	percpu_up_read(&file_rwsem);
1071	if (new_fl)
1072		locks_free_lock(new_fl);
1073	locks_dispose_list(&dispose);
1074	trace_flock_lock_inode(inode, request, error);
1075	return error;
1076}
1077
1078static int posix_lock_inode(struct inode *inode, struct file_lock *request,
1079			    struct file_lock *conflock)
1080{
1081	struct file_lock *fl, *tmp;
1082	struct file_lock *new_fl = NULL;
1083	struct file_lock *new_fl2 = NULL;
1084	struct file_lock *left = NULL;
1085	struct file_lock *right = NULL;
1086	struct file_lock_context *ctx;
1087	int error;
1088	bool added = false;
1089	LIST_HEAD(dispose);
1090	void *owner;
1091	void (*func)(void);
1092
1093	ctx = locks_get_lock_context(inode, request->fl_type);
1094	if (!ctx)
1095		return (request->fl_type == F_UNLCK) ? 0 : -ENOMEM;
1096
1097	/*
1098	 * We may need two file_lock structures for this operation,
1099	 * so we get them in advance to avoid races.
1100	 *
1101	 * In some cases we can be sure, that no new locks will be needed
1102	 */
1103	if (!(request->fl_flags & FL_ACCESS) &&
1104	    (request->fl_type != F_UNLCK ||
1105	     request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
1106		new_fl = locks_alloc_lock();
1107		new_fl2 = locks_alloc_lock();
1108	}
1109
1110retry:
1111	percpu_down_read(&file_rwsem);
1112	spin_lock(&ctx->flc_lock);
1113	/*
1114	 * New lock request. Walk all POSIX locks and look for conflicts. If
1115	 * there are any, either return error or put the request on the
1116	 * blocker's list of waiters and the global blocked_hash.
1117	 */
1118	if (request->fl_type != F_UNLCK) {
1119		list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1120			if (!posix_locks_conflict(request, fl))
1121				continue;
1122			if (fl->fl_lmops && fl->fl_lmops->lm_lock_expirable
1123				&& (*fl->fl_lmops->lm_lock_expirable)(fl)) {
1124				owner = fl->fl_lmops->lm_mod_owner;
1125				func = fl->fl_lmops->lm_expire_lock;
1126				__module_get(owner);
1127				spin_unlock(&ctx->flc_lock);
1128				percpu_up_read(&file_rwsem);
1129				(*func)();
1130				module_put(owner);
1131				goto retry;
1132			}
1133			if (conflock)
1134				locks_copy_conflock(conflock, fl);
1135			error = -EAGAIN;
1136			if (!(request->fl_flags & FL_SLEEP))
1137				goto out;
1138			/*
1139			 * Deadlock detection and insertion into the blocked
1140			 * locks list must be done while holding the same lock!
1141			 */
1142			error = -EDEADLK;
1143			spin_lock(&blocked_lock_lock);
1144			/*
1145			 * Ensure that we don't find any locks blocked on this
1146			 * request during deadlock detection.
1147			 */
1148			__locks_wake_up_blocks(request);
1149			if (likely(!posix_locks_deadlock(request, fl))) {
1150				error = FILE_LOCK_DEFERRED;
1151				__locks_insert_block(fl, request,
1152						     posix_locks_conflict);
1153			}
1154			spin_unlock(&blocked_lock_lock);
1155			goto out;
1156		}
1157	}
1158
1159	/* If we're just looking for a conflict, we're done. */
1160	error = 0;
1161	if (request->fl_flags & FL_ACCESS)
1162		goto out;
1163
1164	/* Find the first old lock with the same owner as the new lock */
1165	list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1166		if (posix_same_owner(request, fl))
1167			break;
1168	}
1169
1170	/* Process locks with this owner. */
1171	list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, fl_list) {
1172		if (!posix_same_owner(request, fl))
1173			break;
1174
1175		/* Detect adjacent or overlapping regions (if same lock type) */
1176		if (request->fl_type == fl->fl_type) {
1177			/* In all comparisons of start vs end, use
1178			 * "start - 1" rather than "end + 1". If end
1179			 * is OFFSET_MAX, end + 1 will become negative.
1180			 */
1181			if (fl->fl_end < request->fl_start - 1)
1182				continue;
1183			/* If the next lock in the list has entirely bigger
1184			 * addresses than the new one, insert the lock here.
1185			 */
1186			if (fl->fl_start - 1 > request->fl_end)
1187				break;
1188
1189			/* If we come here, the new and old lock are of the
1190			 * same type and adjacent or overlapping. Make one
1191			 * lock yielding from the lower start address of both
1192			 * locks to the higher end address.
1193			 */
1194			if (fl->fl_start > request->fl_start)
1195				fl->fl_start = request->fl_start;
1196			else
1197				request->fl_start = fl->fl_start;
1198			if (fl->fl_end < request->fl_end)
1199				fl->fl_end = request->fl_end;
1200			else
1201				request->fl_end = fl->fl_end;
1202			if (added) {
1203				locks_delete_lock_ctx(fl, &dispose);
1204				continue;
1205			}
1206			request = fl;
1207			added = true;
1208		} else {
1209			/* Processing for different lock types is a bit
1210			 * more complex.
1211			 */
1212			if (fl->fl_end < request->fl_start)
1213				continue;
1214			if (fl->fl_start > request->fl_end)
1215				break;
1216			if (request->fl_type == F_UNLCK)
1217				added = true;
1218			if (fl->fl_start < request->fl_start)
1219				left = fl;
1220			/* If the next lock in the list has a higher end
1221			 * address than the new one, insert the new one here.
1222			 */
1223			if (fl->fl_end > request->fl_end) {
1224				right = fl;
1225				break;
1226			}
1227			if (fl->fl_start >= request->fl_start) {
1228				/* The new lock completely replaces an old
1229				 * one (This may happen several times).
1230				 */
1231				if (added) {
1232					locks_delete_lock_ctx(fl, &dispose);
1233					continue;
1234				}
1235				/*
1236				 * Replace the old lock with new_fl, and
1237				 * remove the old one. It's safe to do the
1238				 * insert here since we know that we won't be
1239				 * using new_fl later, and that the lock is
1240				 * just replacing an existing lock.
1241				 */
1242				error = -ENOLCK;
1243				if (!new_fl)
1244					goto out;
1245				locks_copy_lock(new_fl, request);
1246				locks_move_blocks(new_fl, request);
1247				request = new_fl;
1248				new_fl = NULL;
1249				locks_insert_lock_ctx(request, &fl->fl_list);
1250				locks_delete_lock_ctx(fl, &dispose);
1251				added = true;
1252			}
1253		}
1254	}
1255
1256	/*
1257	 * The above code only modifies existing locks in case of merging or
1258	 * replacing. If new lock(s) need to be inserted all modifications are
1259	 * done below this, so it's safe yet to bail out.
1260	 */
1261	error = -ENOLCK; /* "no luck" */
1262	if (right && left == right && !new_fl2)
1263		goto out;
1264
1265	error = 0;
1266	if (!added) {
1267		if (request->fl_type == F_UNLCK) {
1268			if (request->fl_flags & FL_EXISTS)
1269				error = -ENOENT;
1270			goto out;
1271		}
1272
1273		if (!new_fl) {
1274			error = -ENOLCK;
1275			goto out;
1276		}
1277		locks_copy_lock(new_fl, request);
1278		locks_move_blocks(new_fl, request);
1279		locks_insert_lock_ctx(new_fl, &fl->fl_list);
1280		fl = new_fl;
1281		new_fl = NULL;
1282	}
1283	if (right) {
1284		if (left == right) {
1285			/* The new lock breaks the old one in two pieces,
1286			 * so we have to use the second new lock.
1287			 */
1288			left = new_fl2;
1289			new_fl2 = NULL;
1290			locks_copy_lock(left, right);
1291			locks_insert_lock_ctx(left, &fl->fl_list);
1292		}
1293		right->fl_start = request->fl_end + 1;
1294		locks_wake_up_blocks(right);
1295	}
1296	if (left) {
1297		left->fl_end = request->fl_start - 1;
1298		locks_wake_up_blocks(left);
1299	}
1300 out:
1301	spin_unlock(&ctx->flc_lock);
1302	percpu_up_read(&file_rwsem);
1303	/*
1304	 * Free any unused locks.
1305	 */
1306	if (new_fl)
1307		locks_free_lock(new_fl);
1308	if (new_fl2)
1309		locks_free_lock(new_fl2);
1310	locks_dispose_list(&dispose);
1311	trace_posix_lock_inode(inode, request, error);
1312
1313	return error;
1314}
1315
1316/**
1317 * posix_lock_file - Apply a POSIX-style lock to a file
1318 * @filp: The file to apply the lock to
1319 * @fl: The lock to be applied
1320 * @conflock: Place to return a copy of the conflicting lock, if found.
1321 *
1322 * Add a POSIX style lock to a file.
1323 * We merge adjacent & overlapping locks whenever possible.
1324 * POSIX locks are sorted by owner task, then by starting address
1325 *
1326 * Note that if called with an FL_EXISTS argument, the caller may determine
1327 * whether or not a lock was successfully freed by testing the return
1328 * value for -ENOENT.
1329 */
1330int posix_lock_file(struct file *filp, struct file_lock *fl,
1331			struct file_lock *conflock)
1332{
1333	return posix_lock_inode(locks_inode(filp), fl, conflock);
1334}
1335EXPORT_SYMBOL(posix_lock_file);
1336
1337/**
1338 * posix_lock_inode_wait - Apply a POSIX-style lock to a file
1339 * @inode: inode of file to which lock request should be applied
1340 * @fl: The lock to be applied
1341 *
1342 * Apply a POSIX style lock request to an inode.
1343 */
1344static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl)
1345{
1346	int error;
1347	might_sleep ();
1348	for (;;) {
1349		error = posix_lock_inode(inode, fl, NULL);
1350		if (error != FILE_LOCK_DEFERRED)
1351			break;
1352		error = wait_event_interruptible(fl->fl_wait,
1353					list_empty(&fl->fl_blocked_member));
1354		if (error)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1355			break;
 
 
 
 
 
 
 
 
 
 
 
 
1356	}
1357	locks_delete_block(fl);
1358	return error;
1359}
1360
 
 
 
1361static void lease_clear_pending(struct file_lock *fl, int arg)
1362{
1363	switch (arg) {
1364	case F_UNLCK:
1365		fl->fl_flags &= ~FL_UNLOCK_PENDING;
1366		fallthrough;
1367	case F_RDLCK:
1368		fl->fl_flags &= ~FL_DOWNGRADE_PENDING;
1369	}
1370}
1371
1372/* We already had a lease on this file; just change its type */
1373int lease_modify(struct file_lock *fl, int arg, struct list_head *dispose)
1374{
1375	int error = assign_type(fl, arg);
1376
1377	if (error)
1378		return error;
1379	lease_clear_pending(fl, arg);
1380	locks_wake_up_blocks(fl);
1381	if (arg == F_UNLCK) {
1382		struct file *filp = fl->fl_file;
1383
1384		f_delown(filp);
1385		filp->f_owner.signum = 0;
1386		fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
1387		if (fl->fl_fasync != NULL) {
1388			printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
1389			fl->fl_fasync = NULL;
1390		}
1391		locks_delete_lock_ctx(fl, dispose);
1392	}
1393	return 0;
1394}
1395EXPORT_SYMBOL(lease_modify);
1396
1397static bool past_time(unsigned long then)
1398{
1399	if (!then)
1400		/* 0 is a special value meaning "this never expires": */
1401		return false;
1402	return time_after(jiffies, then);
1403}
1404
1405static void time_out_leases(struct inode *inode, struct list_head *dispose)
1406{
1407	struct file_lock_context *ctx = inode->i_flctx;
1408	struct file_lock *fl, *tmp;
1409
1410	lockdep_assert_held(&ctx->flc_lock);
1411
1412	list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
1413		trace_time_out_leases(inode, fl);
1414		if (past_time(fl->fl_downgrade_time))
1415			lease_modify(fl, F_RDLCK, dispose);
1416		if (past_time(fl->fl_break_time))
1417			lease_modify(fl, F_UNLCK, dispose);
1418	}
1419}
1420
1421static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
1422{
1423	bool rc;
1424
1425	if (lease->fl_lmops->lm_breaker_owns_lease
1426			&& lease->fl_lmops->lm_breaker_owns_lease(lease))
1427		return false;
1428	if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT)) {
1429		rc = false;
1430		goto trace;
1431	}
1432	if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE)) {
1433		rc = false;
1434		goto trace;
1435	}
1436
1437	rc = locks_conflict(breaker, lease);
1438trace:
1439	trace_leases_conflict(rc, lease, breaker);
1440	return rc;
1441}
1442
1443static bool
1444any_leases_conflict(struct inode *inode, struct file_lock *breaker)
1445{
1446	struct file_lock_context *ctx = inode->i_flctx;
1447	struct file_lock *fl;
1448
1449	lockdep_assert_held(&ctx->flc_lock);
1450
1451	list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1452		if (leases_conflict(fl, breaker))
1453			return true;
1454	}
1455	return false;
1456}
1457
1458/**
1459 *	__break_lease	-	revoke all outstanding leases on file
1460 *	@inode: the inode of the file to return
1461 *	@mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR:
1462 *	    break all leases
1463 *	@type: FL_LEASE: break leases and delegations; FL_DELEG: break
1464 *	    only delegations
1465 *
1466 *	break_lease (inlined for speed) has checked there already is at least
1467 *	some kind of lock (maybe a lease) on this file.  Leases are broken on
1468 *	a call to open() or truncate().  This function can sleep unless you
1469 *	specified %O_NONBLOCK to your open().
1470 */
1471int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
1472{
1473	int error = 0;
1474	struct file_lock_context *ctx;
1475	struct file_lock *new_fl, *fl, *tmp;
1476	unsigned long break_time;
1477	int want_write = (mode & O_ACCMODE) != O_RDONLY;
1478	LIST_HEAD(dispose);
1479
1480	new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1481	if (IS_ERR(new_fl))
1482		return PTR_ERR(new_fl);
1483	new_fl->fl_flags = type;
1484
1485	/* typically we will check that ctx is non-NULL before calling */
1486	ctx = locks_inode_context(inode);
1487	if (!ctx) {
1488		WARN_ON_ONCE(1);
1489		goto free_lock;
1490	}
1491
1492	percpu_down_read(&file_rwsem);
1493	spin_lock(&ctx->flc_lock);
1494
1495	time_out_leases(inode, &dispose);
1496
1497	if (!any_leases_conflict(inode, new_fl))
1498		goto out;
1499
1500	break_time = 0;
1501	if (lease_break_time > 0) {
1502		break_time = jiffies + lease_break_time * HZ;
1503		if (break_time == 0)
1504			break_time++;	/* so that 0 means no break time */
1505	}
1506
1507	list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
1508		if (!leases_conflict(fl, new_fl))
1509			continue;
1510		if (want_write) {
1511			if (fl->fl_flags & FL_UNLOCK_PENDING)
1512				continue;
1513			fl->fl_flags |= FL_UNLOCK_PENDING;
1514			fl->fl_break_time = break_time;
1515		} else {
1516			if (lease_breaking(fl))
1517				continue;
1518			fl->fl_flags |= FL_DOWNGRADE_PENDING;
1519			fl->fl_downgrade_time = break_time;
1520		}
1521		if (fl->fl_lmops->lm_break(fl))
1522			locks_delete_lock_ctx(fl, &dispose);
1523	}
1524
1525	if (list_empty(&ctx->flc_lease))
1526		goto out;
1527
1528	if (mode & O_NONBLOCK) {
1529		trace_break_lease_noblock(inode, new_fl);
1530		error = -EWOULDBLOCK;
1531		goto out;
1532	}
1533
1534restart:
1535	fl = list_first_entry(&ctx->flc_lease, struct file_lock, fl_list);
1536	break_time = fl->fl_break_time;
1537	if (break_time != 0)
1538		break_time -= jiffies;
1539	if (break_time == 0)
1540		break_time++;
1541	locks_insert_block(fl, new_fl, leases_conflict);
1542	trace_break_lease_block(inode, new_fl);
1543	spin_unlock(&ctx->flc_lock);
1544	percpu_up_read(&file_rwsem);
1545
1546	locks_dispose_list(&dispose);
1547	error = wait_event_interruptible_timeout(new_fl->fl_wait,
1548					list_empty(&new_fl->fl_blocked_member),
1549					break_time);
1550
1551	percpu_down_read(&file_rwsem);
1552	spin_lock(&ctx->flc_lock);
1553	trace_break_lease_unblock(inode, new_fl);
1554	locks_delete_block(new_fl);
1555	if (error >= 0) {
1556		/*
1557		 * Wait for the next conflicting lease that has not been
1558		 * broken yet
1559		 */
1560		if (error == 0)
1561			time_out_leases(inode, &dispose);
1562		if (any_leases_conflict(inode, new_fl))
1563			goto restart;
1564		error = 0;
1565	}
1566out:
1567	spin_unlock(&ctx->flc_lock);
1568	percpu_up_read(&file_rwsem);
1569	locks_dispose_list(&dispose);
1570free_lock:
1571	locks_free_lock(new_fl);
1572	return error;
1573}
 
1574EXPORT_SYMBOL(__break_lease);
1575
1576/**
1577 *	lease_get_mtime - update modified time of an inode with exclusive lease
1578 *	@inode: the inode
1579 *      @time:  pointer to a timespec which contains the last modified time
1580 *
1581 * This is to force NFS clients to flush their caches for files with
1582 * exclusive leases.  The justification is that if someone has an
1583 * exclusive lease, then they could be modifying it.
1584 */
1585void lease_get_mtime(struct inode *inode, struct timespec64 *time)
1586{
1587	bool has_lease = false;
1588	struct file_lock_context *ctx;
1589	struct file_lock *fl;
1590
1591	ctx = locks_inode_context(inode);
1592	if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1593		spin_lock(&ctx->flc_lock);
1594		fl = list_first_entry_or_null(&ctx->flc_lease,
1595					      struct file_lock, fl_list);
1596		if (fl && (fl->fl_type == F_WRLCK))
1597			has_lease = true;
1598		spin_unlock(&ctx->flc_lock);
1599	}
1600
1601	if (has_lease)
1602		*time = current_time(inode);
1603}
 
1604EXPORT_SYMBOL(lease_get_mtime);
1605
1606/**
1607 *	fcntl_getlease - Enquire what lease is currently active
1608 *	@filp: the file
1609 *
1610 *	The value returned by this function will be one of
1611 *	(if no lease break is pending):
1612 *
1613 *	%F_RDLCK to indicate a shared lease is held.
1614 *
1615 *	%F_WRLCK to indicate an exclusive lease is held.
1616 *
1617 *	%F_UNLCK to indicate no lease is held.
1618 *
1619 *	(if a lease break is pending):
1620 *
1621 *	%F_RDLCK to indicate an exclusive lease needs to be
1622 *		changed to a shared lease (or removed).
1623 *
1624 *	%F_UNLCK to indicate the lease needs to be removed.
1625 *
1626 *	XXX: sfr & willy disagree over whether F_INPROGRESS
1627 *	should be returned to userspace.
1628 */
1629int fcntl_getlease(struct file *filp)
1630{
1631	struct file_lock *fl;
1632	struct inode *inode = locks_inode(filp);
1633	struct file_lock_context *ctx;
1634	int type = F_UNLCK;
1635	LIST_HEAD(dispose);
1636
1637	ctx = locks_inode_context(inode);
1638	if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1639		percpu_down_read(&file_rwsem);
1640		spin_lock(&ctx->flc_lock);
1641		time_out_leases(inode, &dispose);
1642		list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1643			if (fl->fl_file != filp)
1644				continue;
1645			type = target_leasetype(fl);
1646			break;
1647		}
1648		spin_unlock(&ctx->flc_lock);
1649		percpu_up_read(&file_rwsem);
1650
1651		locks_dispose_list(&dispose);
1652	}
1653	return type;
1654}
1655
1656/**
1657 * check_conflicting_open - see if the given file points to an inode that has
1658 *			    an existing open that would conflict with the
1659 *			    desired lease.
1660 * @filp:	file to check
1661 * @arg:	type of lease that we're trying to acquire
1662 * @flags:	current lock flags
1663 *
1664 * Check to see if there's an existing open fd on this file that would
1665 * conflict with the lease we're trying to set.
1666 */
1667static int
1668check_conflicting_open(struct file *filp, const long arg, int flags)
1669{
1670	struct inode *inode = locks_inode(filp);
1671	int self_wcount = 0, self_rcount = 0;
1672
1673	if (flags & FL_LAYOUT)
1674		return 0;
1675	if (flags & FL_DELEG)
1676		/* We leave these checks to the caller */
1677		return 0;
1678
1679	if (arg == F_RDLCK)
1680		return inode_is_open_for_write(inode) ? -EAGAIN : 0;
1681	else if (arg != F_WRLCK)
1682		return 0;
1683
1684	/*
1685	 * Make sure that only read/write count is from lease requestor.
1686	 * Note that this will result in denying write leases when i_writecount
1687	 * is negative, which is what we want.  (We shouldn't grant write leases
1688	 * on files open for execution.)
1689	 */
1690	if (filp->f_mode & FMODE_WRITE)
1691		self_wcount = 1;
1692	else if (filp->f_mode & FMODE_READ)
1693		self_rcount = 1;
1694
1695	if (atomic_read(&inode->i_writecount) != self_wcount ||
1696	    atomic_read(&inode->i_readcount) != self_rcount)
1697		return -EAGAIN;
1698
1699	return 0;
 
 
 
 
1700}
1701
1702static int
1703generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **priv)
1704{
1705	struct file_lock *fl, *my_fl = NULL, *lease;
1706	struct inode *inode = locks_inode(filp);
 
1707	struct file_lock_context *ctx;
1708	bool is_deleg = (*flp)->fl_flags & FL_DELEG;
1709	int error;
1710	LIST_HEAD(dispose);
1711
1712	lease = *flp;
1713	trace_generic_add_lease(inode, lease);
1714
1715	/* Note that arg is never F_UNLCK here */
1716	ctx = locks_get_lock_context(inode, arg);
1717	if (!ctx)
1718		return -ENOMEM;
1719
1720	/*
1721	 * In the delegation case we need mutual exclusion with
1722	 * a number of operations that take the i_mutex.  We trylock
1723	 * because delegations are an optional optimization, and if
1724	 * there's some chance of a conflict--we'd rather not
1725	 * bother, maybe that's a sign this just isn't a good file to
1726	 * hand out a delegation on.
1727	 */
1728	if (is_deleg && !inode_trylock(inode))
1729		return -EAGAIN;
1730
1731	if (is_deleg && arg == F_WRLCK) {
1732		/* Write delegations are not currently supported: */
1733		inode_unlock(inode);
1734		WARN_ON_ONCE(1);
1735		return -EINVAL;
1736	}
1737
1738	percpu_down_read(&file_rwsem);
1739	spin_lock(&ctx->flc_lock);
1740	time_out_leases(inode, &dispose);
1741	error = check_conflicting_open(filp, arg, lease->fl_flags);
1742	if (error)
1743		goto out;
1744
1745	/*
1746	 * At this point, we know that if there is an exclusive
1747	 * lease on this file, then we hold it on this filp
1748	 * (otherwise our open of this file would have blocked).
1749	 * And if we are trying to acquire an exclusive lease,
1750	 * then the file is not open by anyone (including us)
1751	 * except for this filp.
1752	 */
1753	error = -EAGAIN;
1754	list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1755		if (fl->fl_file == filp &&
1756		    fl->fl_owner == lease->fl_owner) {
1757			my_fl = fl;
1758			continue;
1759		}
1760
1761		/*
1762		 * No exclusive leases if someone else has a lease on
1763		 * this file:
1764		 */
1765		if (arg == F_WRLCK)
1766			goto out;
1767		/*
1768		 * Modifying our existing lease is OK, but no getting a
1769		 * new lease if someone else is opening for write:
1770		 */
1771		if (fl->fl_flags & FL_UNLOCK_PENDING)
1772			goto out;
1773	}
1774
1775	if (my_fl != NULL) {
1776		lease = my_fl;
1777		error = lease->fl_lmops->lm_change(lease, arg, &dispose);
1778		if (error)
1779			goto out;
1780		goto out_setup;
1781	}
1782
1783	error = -EINVAL;
1784	if (!leases_enable)
1785		goto out;
1786
1787	locks_insert_lock_ctx(lease, &ctx->flc_lease);
1788	/*
1789	 * The check in break_lease() is lockless. It's possible for another
1790	 * open to race in after we did the earlier check for a conflicting
1791	 * open but before the lease was inserted. Check again for a
1792	 * conflicting open and cancel the lease if there is one.
1793	 *
1794	 * We also add a barrier here to ensure that the insertion of the lock
1795	 * precedes these checks.
1796	 */
1797	smp_mb();
1798	error = check_conflicting_open(filp, arg, lease->fl_flags);
1799	if (error) {
1800		locks_unlink_lock_ctx(lease);
1801		goto out;
1802	}
1803
1804out_setup:
1805	if (lease->fl_lmops->lm_setup)
1806		lease->fl_lmops->lm_setup(lease, priv);
1807out:
1808	spin_unlock(&ctx->flc_lock);
1809	percpu_up_read(&file_rwsem);
1810	locks_dispose_list(&dispose);
1811	if (is_deleg)
1812		inode_unlock(inode);
1813	if (!error && !my_fl)
1814		*flp = NULL;
1815	return error;
1816}
1817
1818static int generic_delete_lease(struct file *filp, void *owner)
1819{
1820	int error = -EAGAIN;
1821	struct file_lock *fl, *victim = NULL;
1822	struct inode *inode = locks_inode(filp);
1823	struct file_lock_context *ctx;
1824	LIST_HEAD(dispose);
1825
1826	ctx = locks_inode_context(inode);
1827	if (!ctx) {
1828		trace_generic_delete_lease(inode, NULL);
1829		return error;
1830	}
1831
1832	percpu_down_read(&file_rwsem);
1833	spin_lock(&ctx->flc_lock);
1834	list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1835		if (fl->fl_file == filp &&
1836		    fl->fl_owner == owner) {
1837			victim = fl;
1838			break;
1839		}
1840	}
1841	trace_generic_delete_lease(inode, victim);
1842	if (victim)
1843		error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose);
1844	spin_unlock(&ctx->flc_lock);
1845	percpu_up_read(&file_rwsem);
1846	locks_dispose_list(&dispose);
1847	return error;
1848}
1849
1850/**
1851 *	generic_setlease	-	sets a lease on an open file
1852 *	@filp:	file pointer
1853 *	@arg:	type of lease to obtain
1854 *	@flp:	input - file_lock to use, output - file_lock inserted
1855 *	@priv:	private data for lm_setup (may be NULL if lm_setup
1856 *		doesn't require it)
1857 *
1858 *	The (input) flp->fl_lmops->lm_break function is required
1859 *	by break_lease().
1860 */
1861int generic_setlease(struct file *filp, long arg, struct file_lock **flp,
1862			void **priv)
1863{
1864	struct inode *inode = locks_inode(filp);
1865	int error;
1866
1867	if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE))
1868		return -EACCES;
1869	if (!S_ISREG(inode->i_mode))
1870		return -EINVAL;
1871	error = security_file_lock(filp, arg);
1872	if (error)
1873		return error;
1874
1875	switch (arg) {
1876	case F_UNLCK:
1877		return generic_delete_lease(filp, *priv);
1878	case F_RDLCK:
1879	case F_WRLCK:
1880		if (!(*flp)->fl_lmops->lm_break) {
1881			WARN_ON_ONCE(1);
1882			return -ENOLCK;
1883		}
1884
1885		return generic_add_lease(filp, arg, flp, priv);
1886	default:
1887		return -EINVAL;
1888	}
1889}
1890EXPORT_SYMBOL(generic_setlease);
1891
1892#if IS_ENABLED(CONFIG_SRCU)
1893/*
1894 * Kernel subsystems can register to be notified on any attempt to set
1895 * a new lease with the lease_notifier_chain. This is used by (e.g.) nfsd
1896 * to close files that it may have cached when there is an attempt to set a
1897 * conflicting lease.
1898 */
1899static struct srcu_notifier_head lease_notifier_chain;
1900
1901static inline void
1902lease_notifier_chain_init(void)
1903{
1904	srcu_init_notifier_head(&lease_notifier_chain);
1905}
1906
1907static inline void
1908setlease_notifier(long arg, struct file_lock *lease)
1909{
1910	if (arg != F_UNLCK)
1911		srcu_notifier_call_chain(&lease_notifier_chain, arg, lease);
1912}
1913
1914int lease_register_notifier(struct notifier_block *nb)
1915{
1916	return srcu_notifier_chain_register(&lease_notifier_chain, nb);
1917}
1918EXPORT_SYMBOL_GPL(lease_register_notifier);
1919
1920void lease_unregister_notifier(struct notifier_block *nb)
1921{
1922	srcu_notifier_chain_unregister(&lease_notifier_chain, nb);
1923}
1924EXPORT_SYMBOL_GPL(lease_unregister_notifier);
1925
1926#else /* !IS_ENABLED(CONFIG_SRCU) */
1927static inline void
1928lease_notifier_chain_init(void)
1929{
1930}
1931
1932static inline void
1933setlease_notifier(long arg, struct file_lock *lease)
1934{
1935}
1936
1937int lease_register_notifier(struct notifier_block *nb)
1938{
1939	return 0;
1940}
1941EXPORT_SYMBOL_GPL(lease_register_notifier);
1942
1943void lease_unregister_notifier(struct notifier_block *nb)
1944{
1945}
1946EXPORT_SYMBOL_GPL(lease_unregister_notifier);
1947
1948#endif /* IS_ENABLED(CONFIG_SRCU) */
1949
1950/**
1951 * vfs_setlease        -       sets a lease on an open file
1952 * @filp:	file pointer
1953 * @arg:	type of lease to obtain
1954 * @lease:	file_lock to use when adding a lease
1955 * @priv:	private info for lm_setup when adding a lease (may be
1956 *		NULL if lm_setup doesn't require it)
1957 *
1958 * Call this to establish a lease on the file. The "lease" argument is not
1959 * used for F_UNLCK requests and may be NULL. For commands that set or alter
1960 * an existing lease, the ``(*lease)->fl_lmops->lm_break`` operation must be
1961 * set; if not, this function will return -ENOLCK (and generate a scary-looking
1962 * stack trace).
1963 *
1964 * The "priv" pointer is passed directly to the lm_setup function as-is. It
1965 * may be NULL if the lm_setup operation doesn't require it.
1966 */
1967int
1968vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv)
1969{
1970	if (lease)
1971		setlease_notifier(arg, *lease);
1972	if (filp->f_op->setlease)
1973		return filp->f_op->setlease(filp, arg, lease, priv);
1974	else
1975		return generic_setlease(filp, arg, lease, priv);
1976}
1977EXPORT_SYMBOL_GPL(vfs_setlease);
1978
1979static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
1980{
1981	struct file_lock *fl;
1982	struct fasync_struct *new;
1983	int error;
1984
1985	fl = lease_alloc(filp, arg);
1986	if (IS_ERR(fl))
1987		return PTR_ERR(fl);
1988
1989	new = fasync_alloc();
1990	if (!new) {
1991		locks_free_lock(fl);
1992		return -ENOMEM;
1993	}
1994	new->fa_fd = fd;
1995
1996	error = vfs_setlease(filp, arg, &fl, (void **)&new);
1997	if (fl)
1998		locks_free_lock(fl);
1999	if (new)
2000		fasync_free(new);
2001	return error;
2002}
2003
2004/**
2005 *	fcntl_setlease	-	sets a lease on an open file
2006 *	@fd: open file descriptor
2007 *	@filp: file pointer
2008 *	@arg: type of lease to obtain
2009 *
2010 *	Call this fcntl to establish a lease on the file.
2011 *	Note that you also need to call %F_SETSIG to
2012 *	receive a signal when the lease is broken.
2013 */
2014int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
2015{
2016	if (arg == F_UNLCK)
2017		return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp);
2018	return do_fcntl_add_lease(fd, filp, arg);
2019}
2020
2021/**
2022 * flock_lock_inode_wait - Apply a FLOCK-style lock to a file
2023 * @inode: inode of the file to apply to
2024 * @fl: The lock to be applied
2025 *
2026 * Apply a FLOCK style lock request to an inode.
2027 */
2028static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl)
2029{
2030	int error;
2031	might_sleep();
2032	for (;;) {
2033		error = flock_lock_inode(inode, fl);
2034		if (error != FILE_LOCK_DEFERRED)
2035			break;
2036		error = wait_event_interruptible(fl->fl_wait,
2037				list_empty(&fl->fl_blocked_member));
2038		if (error)
2039			break;
 
 
2040	}
2041	locks_delete_block(fl);
2042	return error;
2043}
2044
2045/**
2046 * locks_lock_inode_wait - Apply a lock to an inode
2047 * @inode: inode of the file to apply to
2048 * @fl: The lock to be applied
2049 *
2050 * Apply a POSIX or FLOCK style lock request to an inode.
2051 */
2052int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl)
2053{
2054	int res = 0;
2055	switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
2056		case FL_POSIX:
2057			res = posix_lock_inode_wait(inode, fl);
2058			break;
2059		case FL_FLOCK:
2060			res = flock_lock_inode_wait(inode, fl);
2061			break;
2062		default:
2063			BUG();
2064	}
2065	return res;
2066}
2067EXPORT_SYMBOL(locks_lock_inode_wait);
2068
2069/**
2070 *	sys_flock: - flock() system call.
2071 *	@fd: the file descriptor to lock.
2072 *	@cmd: the type of lock to apply.
2073 *
2074 *	Apply a %FL_FLOCK style lock to an open file descriptor.
2075 *	The @cmd can be one of:
2076 *
2077 *	- %LOCK_SH -- a shared lock.
2078 *	- %LOCK_EX -- an exclusive lock.
2079 *	- %LOCK_UN -- remove an existing lock.
2080 *	- %LOCK_MAND -- a 'mandatory' flock. (DEPRECATED)
 
2081 *
2082 *	%LOCK_MAND support has been removed from the kernel.
 
2083 */
2084SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
2085{
2086	int can_sleep, error, type;
2087	struct file_lock fl;
2088	struct fd f;
2089
2090	/*
2091	 * LOCK_MAND locks were broken for a long time in that they never
2092	 * conflicted with one another and didn't prevent any sort of open,
2093	 * read or write activity.
2094	 *
2095	 * Just ignore these requests now, to preserve legacy behavior, but
2096	 * throw a warning to let people know that they don't actually work.
2097	 */
2098	if (cmd & LOCK_MAND) {
2099		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);
2100		return 0;
2101	}
2102
2103	type = flock_translate_cmd(cmd & ~LOCK_NB);
2104	if (type < 0)
2105		return type;
2106
2107	error = -EBADF;
2108	f = fdget(fd);
2109	if (!f.file)
2110		return error;
2111
2112	if (type != F_UNLCK && !(f.file->f_mode & (FMODE_READ | FMODE_WRITE)))
2113		goto out_putf;
 
2114
2115	flock_make_lock(f.file, &fl, type);
 
 
2116
2117	error = security_file_lock(f.file, fl.fl_type);
2118	if (error)
 
2119		goto out_putf;
 
2120
2121	can_sleep = !(cmd & LOCK_NB);
2122	if (can_sleep)
2123		fl.fl_flags |= FL_SLEEP;
2124
2125	if (f.file->f_op->flock)
 
 
 
 
2126		error = f.file->f_op->flock(f.file,
2127					    (can_sleep) ? F_SETLKW : F_SETLK,
2128					    &fl);
2129	else
2130		error = locks_lock_file_wait(f.file, &fl);
 
 
 
2131
2132	locks_release_private(&fl);
2133 out_putf:
2134	fdput(f);
2135
2136	return error;
2137}
2138
2139/**
2140 * vfs_test_lock - test file byte range lock
2141 * @filp: The file to test lock for
2142 * @fl: The lock to test; also used to hold result
2143 *
2144 * Returns -ERRNO on failure.  Indicates presence of conflicting lock by
2145 * setting conf->fl_type to something other than F_UNLCK.
2146 */
2147int vfs_test_lock(struct file *filp, struct file_lock *fl)
2148{
2149	WARN_ON_ONCE(filp != fl->fl_file);
2150	if (filp->f_op->lock)
2151		return filp->f_op->lock(filp, F_GETLK, fl);
2152	posix_test_lock(filp, fl);
2153	return 0;
2154}
2155EXPORT_SYMBOL_GPL(vfs_test_lock);
2156
2157/**
2158 * locks_translate_pid - translate a file_lock's fl_pid number into a namespace
2159 * @fl: The file_lock who's fl_pid should be translated
2160 * @ns: The namespace into which the pid should be translated
2161 *
2162 * Used to tranlate a fl_pid into a namespace virtual pid number
2163 */
2164static pid_t locks_translate_pid(struct file_lock *fl, struct pid_namespace *ns)
2165{
2166	pid_t vnr;
2167	struct pid *pid;
2168
2169	if (IS_OFDLCK(fl))
2170		return -1;
2171	if (IS_REMOTELCK(fl))
2172		return fl->fl_pid;
2173	/*
2174	 * If the flock owner process is dead and its pid has been already
2175	 * freed, the translation below won't work, but we still want to show
2176	 * flock owner pid number in init pidns.
2177	 */
2178	if (ns == &init_pid_ns)
2179		return (pid_t)fl->fl_pid;
2180
2181	rcu_read_lock();
2182	pid = find_pid_ns(fl->fl_pid, &init_pid_ns);
2183	vnr = pid_nr_ns(pid, ns);
2184	rcu_read_unlock();
2185	return vnr;
2186}
2187
2188static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
2189{
2190	flock->l_pid = locks_translate_pid(fl, task_active_pid_ns(current));
2191#if BITS_PER_LONG == 32
2192	/*
2193	 * Make sure we can represent the posix lock via
2194	 * legacy 32bit flock.
2195	 */
2196	if (fl->fl_start > OFFT_OFFSET_MAX)
2197		return -EOVERFLOW;
2198	if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
2199		return -EOVERFLOW;
2200#endif
2201	flock->l_start = fl->fl_start;
2202	flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2203		fl->fl_end - fl->fl_start + 1;
2204	flock->l_whence = 0;
2205	flock->l_type = fl->fl_type;
2206	return 0;
2207}
2208
2209#if BITS_PER_LONG == 32
2210static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
2211{
2212	flock->l_pid = locks_translate_pid(fl, task_active_pid_ns(current));
2213	flock->l_start = fl->fl_start;
2214	flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2215		fl->fl_end - fl->fl_start + 1;
2216	flock->l_whence = 0;
2217	flock->l_type = fl->fl_type;
2218}
2219#endif
2220
2221/* Report the first existing lock that would conflict with l.
2222 * This implements the F_GETLK command of fcntl().
2223 */
2224int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock *flock)
2225{
2226	struct file_lock *fl;
2227	int error;
2228
2229	fl = locks_alloc_lock();
2230	if (fl == NULL)
2231		return -ENOMEM;
2232	error = -EINVAL;
2233	if (flock->l_type != F_RDLCK && flock->l_type != F_WRLCK)
2234		goto out;
2235
2236	error = flock_to_posix_lock(filp, fl, flock);
2237	if (error)
2238		goto out;
2239
2240	if (cmd == F_OFD_GETLK) {
2241		error = -EINVAL;
2242		if (flock->l_pid != 0)
2243			goto out;
2244
 
2245		fl->fl_flags |= FL_OFDLCK;
2246		fl->fl_owner = filp;
2247	}
2248
2249	error = vfs_test_lock(filp, fl);
2250	if (error)
2251		goto out;
2252
2253	flock->l_type = fl->fl_type;
2254	if (fl->fl_type != F_UNLCK) {
2255		error = posix_lock_to_flock(flock, fl);
2256		if (error)
2257			goto out;
2258	}
2259out:
2260	locks_free_lock(fl);
2261	return error;
2262}
2263
2264/**
2265 * vfs_lock_file - file byte range lock
2266 * @filp: The file to apply the lock to
2267 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
2268 * @fl: The lock to be applied
2269 * @conf: Place to return a copy of the conflicting lock, if found.
2270 *
2271 * A caller that doesn't care about the conflicting lock may pass NULL
2272 * as the final argument.
2273 *
2274 * If the filesystem defines a private ->lock() method, then @conf will
2275 * be left unchanged; so a caller that cares should initialize it to
2276 * some acceptable default.
2277 *
2278 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
2279 * locks, the ->lock() interface may return asynchronously, before the lock has
2280 * been granted or denied by the underlying filesystem, if (and only if)
2281 * lm_grant is set. Callers expecting ->lock() to return asynchronously
2282 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
2283 * the request is for a blocking lock. When ->lock() does return asynchronously,
2284 * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
2285 * request completes.
2286 * If the request is for non-blocking lock the file system should return
2287 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
2288 * with the result. If the request timed out the callback routine will return a
2289 * nonzero return code and the file system should release the lock. The file
2290 * system is also responsible to keep a corresponding posix lock when it
2291 * grants a lock so the VFS can find out which locks are locally held and do
2292 * the correct lock cleanup when required.
2293 * The underlying filesystem must not drop the kernel lock or call
2294 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
2295 * return code.
2296 */
2297int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
2298{
2299	WARN_ON_ONCE(filp != fl->fl_file);
2300	if (filp->f_op->lock)
2301		return filp->f_op->lock(filp, cmd, fl);
2302	else
2303		return posix_lock_file(filp, fl, conf);
2304}
2305EXPORT_SYMBOL_GPL(vfs_lock_file);
2306
2307static int do_lock_file_wait(struct file *filp, unsigned int cmd,
2308			     struct file_lock *fl)
2309{
2310	int error;
2311
2312	error = security_file_lock(filp, fl->fl_type);
2313	if (error)
2314		return error;
2315
2316	for (;;) {
2317		error = vfs_lock_file(filp, cmd, fl, NULL);
2318		if (error != FILE_LOCK_DEFERRED)
2319			break;
2320		error = wait_event_interruptible(fl->fl_wait,
2321					list_empty(&fl->fl_blocked_member));
2322		if (error)
2323			break;
 
 
2324	}
2325	locks_delete_block(fl);
2326
2327	return error;
2328}
2329
2330/* Ensure that fl->fl_file has compatible f_mode for F_SETLK calls */
2331static int
2332check_fmode_for_setlk(struct file_lock *fl)
2333{
2334	switch (fl->fl_type) {
2335	case F_RDLCK:
2336		if (!(fl->fl_file->f_mode & FMODE_READ))
2337			return -EBADF;
2338		break;
2339	case F_WRLCK:
2340		if (!(fl->fl_file->f_mode & FMODE_WRITE))
2341			return -EBADF;
2342	}
2343	return 0;
2344}
2345
2346/* Apply the lock described by l to an open file descriptor.
2347 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2348 */
2349int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
2350		struct flock *flock)
2351{
2352	struct file_lock *file_lock = locks_alloc_lock();
2353	struct inode *inode = locks_inode(filp);
2354	struct file *f;
2355	int error;
2356
2357	if (file_lock == NULL)
2358		return -ENOLCK;
2359
 
 
 
 
 
 
 
 
2360	error = flock_to_posix_lock(filp, file_lock, flock);
2361	if (error)
2362		goto out;
2363
2364	error = check_fmode_for_setlk(file_lock);
2365	if (error)
2366		goto out;
2367
2368	/*
2369	 * If the cmd is requesting file-private locks, then set the
2370	 * FL_OFDLCK flag and override the owner.
2371	 */
2372	switch (cmd) {
2373	case F_OFD_SETLK:
2374		error = -EINVAL;
2375		if (flock->l_pid != 0)
2376			goto out;
2377
2378		cmd = F_SETLK;
2379		file_lock->fl_flags |= FL_OFDLCK;
2380		file_lock->fl_owner = filp;
2381		break;
2382	case F_OFD_SETLKW:
2383		error = -EINVAL;
2384		if (flock->l_pid != 0)
2385			goto out;
2386
2387		cmd = F_SETLKW;
2388		file_lock->fl_flags |= FL_OFDLCK;
2389		file_lock->fl_owner = filp;
2390		fallthrough;
2391	case F_SETLKW:
2392		file_lock->fl_flags |= FL_SLEEP;
2393	}
2394
2395	error = do_lock_file_wait(filp, cmd, file_lock);
2396
2397	/*
2398	 * Attempt to detect a close/fcntl race and recover by releasing the
2399	 * lock that was just acquired. There is no need to do that when we're
2400	 * unlocking though, or for OFD locks.
2401	 */
2402	if (!error && file_lock->fl_type != F_UNLCK &&
2403	    !(file_lock->fl_flags & FL_OFDLCK)) {
2404		struct files_struct *files = current->files;
2405		/*
2406		 * We need that spin_lock here - it prevents reordering between
2407		 * update of i_flctx->flc_posix and check for it done in
2408		 * close(). rcu_read_lock() wouldn't do.
2409		 */
2410		spin_lock(&files->file_lock);
2411		f = files_lookup_fd_locked(files, fd);
2412		spin_unlock(&files->file_lock);
2413		if (f != filp) {
2414			file_lock->fl_type = F_UNLCK;
2415			error = do_lock_file_wait(filp, cmd, file_lock);
2416			WARN_ON_ONCE(error);
2417			error = -EBADF;
2418		}
2419	}
2420out:
2421	trace_fcntl_setlk(inode, file_lock, error);
2422	locks_free_lock(file_lock);
2423	return error;
2424}
2425
2426#if BITS_PER_LONG == 32
2427/* Report the first existing lock that would conflict with l.
2428 * This implements the F_GETLK command of fcntl().
2429 */
2430int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 *flock)
2431{
2432	struct file_lock *fl;
2433	int error;
2434
2435	fl = locks_alloc_lock();
2436	if (fl == NULL)
2437		return -ENOMEM;
2438
2439	error = -EINVAL;
2440	if (flock->l_type != F_RDLCK && flock->l_type != F_WRLCK)
2441		goto out;
2442
2443	error = flock64_to_posix_lock(filp, fl, flock);
2444	if (error)
2445		goto out;
2446
2447	if (cmd == F_OFD_GETLK) {
2448		error = -EINVAL;
2449		if (flock->l_pid != 0)
2450			goto out;
2451
2452		cmd = F_GETLK64;
2453		fl->fl_flags |= FL_OFDLCK;
2454		fl->fl_owner = filp;
2455	}
2456
2457	error = vfs_test_lock(filp, fl);
2458	if (error)
2459		goto out;
2460
2461	flock->l_type = fl->fl_type;
2462	if (fl->fl_type != F_UNLCK)
2463		posix_lock_to_flock64(flock, fl);
2464
2465out:
2466	locks_free_lock(fl);
2467	return error;
2468}
2469
2470/* Apply the lock described by l to an open file descriptor.
2471 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2472 */
2473int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
2474		struct flock64 *flock)
2475{
2476	struct file_lock *file_lock = locks_alloc_lock();
 
2477	struct file *f;
2478	int error;
2479
2480	if (file_lock == NULL)
2481		return -ENOLCK;
2482
 
 
 
 
 
 
 
 
2483	error = flock64_to_posix_lock(filp, file_lock, flock);
2484	if (error)
2485		goto out;
2486
2487	error = check_fmode_for_setlk(file_lock);
2488	if (error)
2489		goto out;
2490
2491	/*
2492	 * If the cmd is requesting file-private locks, then set the
2493	 * FL_OFDLCK flag and override the owner.
2494	 */
2495	switch (cmd) {
2496	case F_OFD_SETLK:
2497		error = -EINVAL;
2498		if (flock->l_pid != 0)
2499			goto out;
2500
2501		cmd = F_SETLK64;
2502		file_lock->fl_flags |= FL_OFDLCK;
2503		file_lock->fl_owner = filp;
2504		break;
2505	case F_OFD_SETLKW:
2506		error = -EINVAL;
2507		if (flock->l_pid != 0)
2508			goto out;
2509
2510		cmd = F_SETLKW64;
2511		file_lock->fl_flags |= FL_OFDLCK;
2512		file_lock->fl_owner = filp;
2513		fallthrough;
2514	case F_SETLKW64:
2515		file_lock->fl_flags |= FL_SLEEP;
2516	}
2517
2518	error = do_lock_file_wait(filp, cmd, file_lock);
2519
2520	/*
2521	 * Attempt to detect a close/fcntl race and recover by releasing the
2522	 * lock that was just acquired. There is no need to do that when we're
2523	 * unlocking though, or for OFD locks.
2524	 */
2525	if (!error && file_lock->fl_type != F_UNLCK &&
2526	    !(file_lock->fl_flags & FL_OFDLCK)) {
2527		struct files_struct *files = current->files;
2528		/*
2529		 * We need that spin_lock here - it prevents reordering between
2530		 * update of i_flctx->flc_posix and check for it done in
2531		 * close(). rcu_read_lock() wouldn't do.
2532		 */
2533		spin_lock(&files->file_lock);
2534		f = files_lookup_fd_locked(files, fd);
2535		spin_unlock(&files->file_lock);
2536		if (f != filp) {
2537			file_lock->fl_type = F_UNLCK;
2538			error = do_lock_file_wait(filp, cmd, file_lock);
2539			WARN_ON_ONCE(error);
2540			error = -EBADF;
2541		}
2542	}
2543out:
2544	locks_free_lock(file_lock);
2545	return error;
2546}
2547#endif /* BITS_PER_LONG == 32 */
2548
2549/*
2550 * This function is called when the file is being removed
2551 * from the task's fd array.  POSIX locks belonging to this task
2552 * are deleted at this time.
2553 */
2554void locks_remove_posix(struct file *filp, fl_owner_t owner)
2555{
2556	int error;
2557	struct inode *inode = locks_inode(filp);
2558	struct file_lock lock;
2559	struct file_lock_context *ctx;
2560
2561	/*
2562	 * If there are no locks held on this file, we don't need to call
2563	 * posix_lock_file().  Another process could be setting a lock on this
2564	 * file at the same time, but we wouldn't remove that lock anyway.
2565	 */
2566	ctx = locks_inode_context(inode);
2567	if (!ctx || list_empty(&ctx->flc_posix))
2568		return;
2569
2570	locks_init_lock(&lock);
2571	lock.fl_type = F_UNLCK;
2572	lock.fl_flags = FL_POSIX | FL_CLOSE;
2573	lock.fl_start = 0;
2574	lock.fl_end = OFFSET_MAX;
2575	lock.fl_owner = owner;
2576	lock.fl_pid = current->tgid;
2577	lock.fl_file = filp;
2578	lock.fl_ops = NULL;
2579	lock.fl_lmops = NULL;
2580
2581	error = vfs_lock_file(filp, F_SETLK, &lock, NULL);
2582
2583	if (lock.fl_ops && lock.fl_ops->fl_release_private)
2584		lock.fl_ops->fl_release_private(&lock);
2585	trace_locks_remove_posix(inode, &lock, error);
2586}
 
2587EXPORT_SYMBOL(locks_remove_posix);
2588
2589/* The i_flctx must be valid when calling into here */
2590static void
2591locks_remove_flock(struct file *filp, struct file_lock_context *flctx)
2592{
2593	struct file_lock fl;
 
 
 
 
 
 
 
2594	struct inode *inode = locks_inode(filp);
2595
2596	if (list_empty(&flctx->flc_flock))
2597		return;
2598
2599	flock_make_lock(filp, &fl, F_UNLCK);
2600	fl.fl_flags |= FL_CLOSE;
2601
2602	if (filp->f_op->flock)
2603		filp->f_op->flock(filp, F_SETLKW, &fl);
2604	else
2605		flock_lock_inode(inode, &fl);
2606
2607	if (fl.fl_ops && fl.fl_ops->fl_release_private)
2608		fl.fl_ops->fl_release_private(&fl);
2609}
2610
2611/* The i_flctx must be valid when calling into here */
2612static void
2613locks_remove_lease(struct file *filp, struct file_lock_context *ctx)
2614{
2615	struct file_lock *fl, *tmp;
2616	LIST_HEAD(dispose);
2617
2618	if (list_empty(&ctx->flc_lease))
2619		return;
2620
2621	percpu_down_read(&file_rwsem);
2622	spin_lock(&ctx->flc_lock);
2623	list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list)
2624		if (filp == fl->fl_file)
2625			lease_modify(fl, F_UNLCK, &dispose);
2626	spin_unlock(&ctx->flc_lock);
2627	percpu_up_read(&file_rwsem);
2628
2629	locks_dispose_list(&dispose);
2630}
2631
2632/*
2633 * This function is called on the last close of an open file.
2634 */
2635void locks_remove_file(struct file *filp)
2636{
2637	struct file_lock_context *ctx;
2638
2639	ctx = locks_inode_context(locks_inode(filp));
2640	if (!ctx)
2641		return;
2642
2643	/* remove any OFD locks */
2644	locks_remove_posix(filp, filp);
2645
2646	/* remove flock locks */
2647	locks_remove_flock(filp, ctx);
2648
2649	/* remove any leases */
2650	locks_remove_lease(filp, ctx);
2651
2652	spin_lock(&ctx->flc_lock);
2653	locks_check_ctx_file_list(filp, &ctx->flc_posix, "POSIX");
2654	locks_check_ctx_file_list(filp, &ctx->flc_flock, "FLOCK");
2655	locks_check_ctx_file_list(filp, &ctx->flc_lease, "LEASE");
2656	spin_unlock(&ctx->flc_lock);
2657}
2658
2659/**
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2660 * vfs_cancel_lock - file byte range unblock lock
2661 * @filp: The file to apply the unblock to
2662 * @fl: The lock to be unblocked
2663 *
2664 * Used by lock managers to cancel blocked requests
2665 */
2666int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2667{
2668	WARN_ON_ONCE(filp != fl->fl_file);
2669	if (filp->f_op->lock)
2670		return filp->f_op->lock(filp, F_CANCELLK, fl);
2671	return 0;
2672}
2673EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2674
2675/**
2676 * vfs_inode_has_locks - are any file locks held on @inode?
2677 * @inode: inode to check for locks
2678 *
2679 * Return true if there are any FL_POSIX or FL_FLOCK locks currently
2680 * set on @inode.
2681 */
2682bool vfs_inode_has_locks(struct inode *inode)
2683{
2684	struct file_lock_context *ctx;
2685	bool ret;
2686
2687	ctx = locks_inode_context(inode);
2688	if (!ctx)
2689		return false;
2690
2691	spin_lock(&ctx->flc_lock);
2692	ret = !list_empty(&ctx->flc_posix) || !list_empty(&ctx->flc_flock);
2693	spin_unlock(&ctx->flc_lock);
2694	return ret;
2695}
2696EXPORT_SYMBOL_GPL(vfs_inode_has_locks);
2697
2698#ifdef CONFIG_PROC_FS
2699#include <linux/proc_fs.h>
2700#include <linux/seq_file.h>
2701
2702struct locks_iterator {
2703	int	li_cpu;
2704	loff_t	li_pos;
2705};
2706
2707static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2708			    loff_t id, char *pfx, int repeat)
2709{
2710	struct inode *inode = NULL;
2711	unsigned int fl_pid;
2712	struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);
2713	int type;
2714
2715	fl_pid = locks_translate_pid(fl, proc_pidns);
2716	/*
2717	 * If lock owner is dead (and pid is freed) or not visible in current
2718	 * pidns, zero is shown as a pid value. Check lock info from
2719	 * init_pid_ns to get saved lock pid value.
2720	 */
 
 
2721
2722	if (fl->fl_file != NULL)
2723		inode = locks_inode(fl->fl_file);
2724
2725	seq_printf(f, "%lld: ", id);
2726
2727	if (repeat)
2728		seq_printf(f, "%*s", repeat - 1 + (int)strlen(pfx), pfx);
2729
2730	if (IS_POSIX(fl)) {
2731		if (fl->fl_flags & FL_ACCESS)
2732			seq_puts(f, "ACCESS");
2733		else if (IS_OFDLCK(fl))
2734			seq_puts(f, "OFDLCK");
2735		else
2736			seq_puts(f, "POSIX ");
2737
2738		seq_printf(f, " %s ",
2739			     (inode == NULL) ? "*NOINODE*" : "ADVISORY ");
 
2740	} else if (IS_FLOCK(fl)) {
2741		seq_puts(f, "FLOCK  ADVISORY  ");
 
 
 
 
2742	} else if (IS_LEASE(fl)) {
2743		if (fl->fl_flags & FL_DELEG)
2744			seq_puts(f, "DELEG  ");
2745		else
2746			seq_puts(f, "LEASE  ");
2747
2748		if (lease_breaking(fl))
2749			seq_puts(f, "BREAKING  ");
2750		else if (fl->fl_file)
2751			seq_puts(f, "ACTIVE    ");
2752		else
2753			seq_puts(f, "BREAKER   ");
2754	} else {
2755		seq_puts(f, "UNKNOWN UNKNOWN  ");
2756	}
2757	type = IS_LEASE(fl) ? target_leasetype(fl) : fl->fl_type;
2758
2759	seq_printf(f, "%s ", (type == F_WRLCK) ? "WRITE" :
2760			     (type == F_RDLCK) ? "READ" : "UNLCK");
 
 
 
 
 
 
 
2761	if (inode) {
2762		/* userspace relies on this representation of dev_t */
2763		seq_printf(f, "%d %02x:%02x:%lu ", fl_pid,
2764				MAJOR(inode->i_sb->s_dev),
2765				MINOR(inode->i_sb->s_dev), inode->i_ino);
2766	} else {
2767		seq_printf(f, "%d <none>:0 ", fl_pid);
2768	}
2769	if (IS_POSIX(fl)) {
2770		if (fl->fl_end == OFFSET_MAX)
2771			seq_printf(f, "%Ld EOF\n", fl->fl_start);
2772		else
2773			seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2774	} else {
2775		seq_puts(f, "0 EOF\n");
2776	}
2777}
2778
2779static struct file_lock *get_next_blocked_member(struct file_lock *node)
2780{
2781	struct file_lock *tmp;
2782
2783	/* NULL node or root node */
2784	if (node == NULL || node->fl_blocker == NULL)
2785		return NULL;
2786
2787	/* Next member in the linked list could be itself */
2788	tmp = list_next_entry(node, fl_blocked_member);
2789	if (list_entry_is_head(tmp, &node->fl_blocker->fl_blocked_requests, fl_blocked_member)
2790		|| tmp == node) {
2791		return NULL;
2792	}
2793
2794	return tmp;
2795}
2796
2797static int locks_show(struct seq_file *f, void *v)
2798{
2799	struct locks_iterator *iter = f->private;
2800	struct file_lock *cur, *tmp;
2801	struct pid_namespace *proc_pidns = proc_pid_ns(file_inode(f->file)->i_sb);
2802	int level = 0;
2803
2804	cur = hlist_entry(v, struct file_lock, fl_link);
2805
2806	if (locks_translate_pid(cur, proc_pidns) == 0)
2807		return 0;
2808
2809	/* View this crossed linked list as a binary tree, the first member of fl_blocked_requests
2810	 * is the left child of current node, the next silibing in fl_blocked_member is the
2811	 * right child, we can alse get the parent of current node from fl_blocker, so this
2812	 * question becomes traversal of a binary tree
2813	 */
2814	while (cur != NULL) {
2815		if (level)
2816			lock_get_status(f, cur, iter->li_pos, "-> ", level);
2817		else
2818			lock_get_status(f, cur, iter->li_pos, "", level);
2819
2820		if (!list_empty(&cur->fl_blocked_requests)) {
2821			/* Turn left */
2822			cur = list_first_entry_or_null(&cur->fl_blocked_requests,
2823				struct file_lock, fl_blocked_member);
2824			level++;
2825		} else {
2826			/* Turn right */
2827			tmp = get_next_blocked_member(cur);
2828			/* Fall back to parent node */
2829			while (tmp == NULL && cur->fl_blocker != NULL) {
2830				cur = cur->fl_blocker;
2831				level--;
2832				tmp = get_next_blocked_member(cur);
2833			}
2834			cur = tmp;
2835		}
2836	}
2837
2838	return 0;
2839}
2840
2841static void __show_fd_locks(struct seq_file *f,
2842			struct list_head *head, int *id,
2843			struct file *filp, struct files_struct *files)
2844{
2845	struct file_lock *fl;
2846
2847	list_for_each_entry(fl, head, fl_list) {
2848
2849		if (filp != fl->fl_file)
2850			continue;
2851		if (fl->fl_owner != files &&
2852		    fl->fl_owner != filp)
2853			continue;
2854
2855		(*id)++;
2856		seq_puts(f, "lock:\t");
2857		lock_get_status(f, fl, *id, "", 0);
2858	}
2859}
2860
2861void show_fd_locks(struct seq_file *f,
2862		  struct file *filp, struct files_struct *files)
2863{
2864	struct inode *inode = locks_inode(filp);
2865	struct file_lock_context *ctx;
2866	int id = 0;
2867
2868	ctx = locks_inode_context(inode);
2869	if (!ctx)
2870		return;
2871
2872	spin_lock(&ctx->flc_lock);
2873	__show_fd_locks(f, &ctx->flc_flock, &id, filp, files);
2874	__show_fd_locks(f, &ctx->flc_posix, &id, filp, files);
2875	__show_fd_locks(f, &ctx->flc_lease, &id, filp, files);
2876	spin_unlock(&ctx->flc_lock);
2877}
2878
2879static void *locks_start(struct seq_file *f, loff_t *pos)
2880	__acquires(&blocked_lock_lock)
2881{
2882	struct locks_iterator *iter = f->private;
2883
2884	iter->li_pos = *pos + 1;
2885	percpu_down_write(&file_rwsem);
2886	spin_lock(&blocked_lock_lock);
2887	return seq_hlist_start_percpu(&file_lock_list.hlist, &iter->li_cpu, *pos);
2888}
2889
2890static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2891{
2892	struct locks_iterator *iter = f->private;
2893
2894	++iter->li_pos;
2895	return seq_hlist_next_percpu(v, &file_lock_list.hlist, &iter->li_cpu, pos);
2896}
2897
2898static void locks_stop(struct seq_file *f, void *v)
2899	__releases(&blocked_lock_lock)
2900{
2901	spin_unlock(&blocked_lock_lock);
2902	percpu_up_write(&file_rwsem);
2903}
2904
2905static const struct seq_operations locks_seq_operations = {
2906	.start	= locks_start,
2907	.next	= locks_next,
2908	.stop	= locks_stop,
2909	.show	= locks_show,
2910};
2911
 
 
 
 
 
 
 
 
 
 
 
 
 
2912static int __init proc_locks_init(void)
2913{
2914	proc_create_seq_private("locks", 0, NULL, &locks_seq_operations,
2915			sizeof(struct locks_iterator), NULL);
2916	return 0;
2917}
2918fs_initcall(proc_locks_init);
2919#endif
2920
2921static int __init filelock_init(void)
2922{
2923	int i;
2924
2925	flctx_cache = kmem_cache_create("file_lock_ctx",
2926			sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL);
2927
2928	filelock_cache = kmem_cache_create("file_lock_cache",
2929			sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
2930
 
2931	for_each_possible_cpu(i) {
2932		struct file_lock_list_struct *fll = per_cpu_ptr(&file_lock_list, i);
2933
2934		spin_lock_init(&fll->lock);
2935		INIT_HLIST_HEAD(&fll->hlist);
2936	}
2937
2938	lease_notifier_chain_init();
2939	return 0;
2940}
 
2941core_initcall(filelock_init);