1/*
   2 *  linux/fs/locks.c
   3 *
   4 *  Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls.
   5 *  Doug Evans (dje@spiff.uucp), August 07, 1992
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   6 *
   7 *  Deadlock detection added.
   8 *  FIXME: one thing isn't handled yet:
   9 *	- mandatory locks (requires lots of changes elsewhere)
  10 *  Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994.
  11 *
  12 *  Miscellaneous edits, and a total rewrite of posix_lock_file() code.
  13 *  Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994
  14 *  
  15 *  Converted file_lock_table to a linked list from an array, which eliminates
  16 *  the limits on how many active file locks are open.
  17 *  Chad Page (pageone@netcom.com), November 27, 1994
  18 * 
  19 *  Removed dependency on file descriptors. dup()'ed file descriptors now
  20 *  get the same locks as the original file descriptors, and a close() on
  21 *  any file descriptor removes ALL the locks on the file for the current
  22 *  process. Since locks still depend on the process id, locks are inherited
  23 *  after an exec() but not after a fork(). This agrees with POSIX, and both
  24 *  BSD and SVR4 practice.
  25 *  Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995
  26 *
  27 *  Scrapped free list which is redundant now that we allocate locks
  28 *  dynamically with kmalloc()/kfree().
  29 *  Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995
  30 *
  31 *  Implemented two lock personalities - FL_FLOCK and FL_POSIX.
  32 *
  33 *  FL_POSIX locks are created with calls to fcntl() and lockf() through the
  34 *  fcntl() system call. They have the semantics described above.
  35 *
  36 *  FL_FLOCK locks are created with calls to flock(), through the flock()
  37 *  system call, which is new. Old C libraries implement flock() via fcntl()
  38 *  and will continue to use the old, broken implementation.
  39 *
  40 *  FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated
  41 *  with a file pointer (filp). As a result they can be shared by a parent
  42 *  process and its children after a fork(). They are removed when the last
  43 *  file descriptor referring to the file pointer is closed (unless explicitly
  44 *  unlocked). 
  45 *
  46 *  FL_FLOCK locks never deadlock, an existing lock is always removed before
  47 *  upgrading from shared to exclusive (or vice versa). When this happens
  48 *  any processes blocked by the current lock are woken up and allowed to
  49 *  run before the new lock is applied.
  50 *  Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995
  51 *
  52 *  Removed some race conditions in flock_lock_file(), marked other possible
  53 *  races. Just grep for FIXME to see them. 
  54 *  Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996.
  55 *
  56 *  Addressed Dmitry's concerns. Deadlock checking no longer recursive.
  57 *  Lock allocation changed to GFP_ATOMIC as we can't afford to sleep
  58 *  once we've checked for blocking and deadlocking.
  59 *  Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996.
  60 *
  61 *  Initial implementation of mandatory locks. SunOS turned out to be
  62 *  a rotten model, so I implemented the "obvious" semantics.
  63 *  See 'Documentation/filesystems/mandatory-locking.txt' for details.
  64 *  Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
  65 *
  66 *  Don't allow mandatory locks on mmap()'ed files. Added simple functions to
  67 *  check if a file has mandatory locks, used by mmap(), open() and creat() to
  68 *  see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
  69 *  Manual, Section 2.
  70 *  Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996.
  71 *
  72 *  Tidied up block list handling. Added '/proc/locks' interface.
  73 *  Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
  74 *
  75 *  Fixed deadlock condition for pathological code that mixes calls to
  76 *  flock() and fcntl().
  77 *  Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996.
  78 *
  79 *  Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use
  80 *  for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to
  81 *  guarantee sensible behaviour in the case where file system modules might
  82 *  be compiled with different options than the kernel itself.
  83 *  Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
  84 *
  85 *  Added a couple of missing wake_up() calls. Thanks to Thomas Meckel
  86 *  (Thomas.Meckel@mni.fh-giessen.de) for spotting this.
  87 *  Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
  88 *
  89 *  Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK
  90 *  locks. Changed process synchronisation to avoid dereferencing locks that
  91 *  have already been freed.
  92 *  Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996.
  93 *
  94 *  Made the block list a circular list to minimise searching in the list.
  95 *  Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996.
  96 *
  97 *  Made mandatory locking a mount option. Default is not to allow mandatory
  98 *  locking.
  99 *  Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996.
 100 *
 101 *  Some adaptations for NFS support.
 102 *  Olaf Kirch (okir@monad.swb.de), Dec 1996,
 103 *
 104 *  Fixed /proc/locks interface so that we can't overrun the buffer we are handed.
 105 *  Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997.
 106 *
 107 *  Use slab allocator instead of kmalloc/kfree.
 108 *  Use generic list implementation from <linux/list.h>.
 109 *  Sped up posix_locks_deadlock by only considering blocked locks.
 110 *  Matthew Wilcox <willy@debian.org>, March, 2000.
 111 *
 112 *  Leases and LOCK_MAND
 113 *  Matthew Wilcox <willy@debian.org>, June, 2000.
 114 *  Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000.
 115 */
 116
 117#include <linux/capability.h>
 118#include <linux/file.h>
 119#include <linux/fdtable.h>
 
 120#include <linux/fs.h>
 121#include <linux/init.h>
 122#include <linux/security.h>
 123#include <linux/slab.h>
 124#include <linux/syscalls.h>
 125#include <linux/time.h>
 126#include <linux/rcupdate.h>
 127#include <linux/pid_namespace.h>
 128#include <linux/hashtable.h>
 129#include <linux/percpu.h>
 
 130
 131#define CREATE_TRACE_POINTS
 132#include <trace/events/filelock.h>
 133
 134#include <linux/uaccess.h>
 135
 136#define IS_POSIX(fl)	(fl->fl_flags & FL_POSIX)
 137#define IS_FLOCK(fl)	(fl->fl_flags & FL_FLOCK)
 138#define IS_LEASE(fl)	(fl->fl_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT))
 139#define IS_OFDLCK(fl)	(fl->fl_flags & FL_OFDLCK)
 140
 141static inline bool is_remote_lock(struct file *filp)
 142{
 143	return likely(!(filp->f_path.dentry->d_sb->s_flags & MS_NOREMOTELOCK));
 144}
 145
 146static bool lease_breaking(struct file_lock *fl)
 147{
 148	return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
 149}
 150
 151static int target_leasetype(struct file_lock *fl)
 152{
 153	if (fl->fl_flags & FL_UNLOCK_PENDING)
 154		return F_UNLCK;
 155	if (fl->fl_flags & FL_DOWNGRADE_PENDING)
 156		return F_RDLCK;
 157	return fl->fl_type;
 158}
 159
 160int leases_enable = 1;
 161int lease_break_time = 45;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 162
 163/*
 164 * The global file_lock_list is only used for displaying /proc/locks, so we
 165 * keep a list on each CPU, with each list protected by its own spinlock.
 166 * Global serialization is done using file_rwsem.
 167 *
 168 * Note that alterations to the list also require that the relevant flc_lock is
 169 * held.
 170 */
 171struct file_lock_list_struct {
 172	spinlock_t		lock;
 173	struct hlist_head	hlist;
 174};
 175static DEFINE_PER_CPU(struct file_lock_list_struct, file_lock_list);
 176DEFINE_STATIC_PERCPU_RWSEM(file_rwsem);
 177
 
 178/*
 179 * The blocked_hash is used to find POSIX lock loops for deadlock detection.
 180 * It is protected by blocked_lock_lock.
 181 *
 182 * We hash locks by lockowner in order to optimize searching for the lock a
 183 * particular lockowner is waiting on.
 184 *
 185 * FIXME: make this value scale via some heuristic? We generally will want more
 186 * buckets when we have more lockowners holding locks, but that's a little
 187 * difficult to determine without knowing what the workload will look like.
 188 */
 189#define BLOCKED_HASH_BITS	7
 190static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
 191
 192/*
 193 * This lock protects the blocked_hash. Generally, if you're accessing it, you
 194 * want to be holding this lock.
 195 *
 196 * In addition, it also protects the fl->fl_block list, and the fl->fl_next
 197 * pointer for file_lock structures that are acting as lock requests (in
 198 * contrast to those that are acting as records of acquired locks).
 199 *
 200 * Note that when we acquire this lock in order to change the above fields,
 201 * we often hold the flc_lock as well. In certain cases, when reading the fields
 202 * protected by this lock, we can skip acquiring it iff we already hold the
 203 * flc_lock.
 204 *
 205 * In particular, adding an entry to the fl_block list requires that you hold
 206 * both the flc_lock and the blocked_lock_lock (acquired in that order).
 207 * Deleting an entry from the list however only requires the file_lock_lock.
 208 */
 209static DEFINE_SPINLOCK(blocked_lock_lock);
 210
 211static struct kmem_cache *flctx_cache __read_mostly;
 212static struct kmem_cache *filelock_cache __read_mostly;
 
 213
 214static struct file_lock_context *
 215locks_get_lock_context(struct inode *inode, int type)
 216{
 217	struct file_lock_context *ctx;
 218
 219	/* paired with cmpxchg() below */
 220	ctx = smp_load_acquire(&inode->i_flctx);
 221	if (likely(ctx) || type == F_UNLCK)
 222		goto out;
 223
 224	ctx = kmem_cache_alloc(flctx_cache, GFP_KERNEL);
 225	if (!ctx)
 226		goto out;
 227
 228	spin_lock_init(&ctx->flc_lock);
 229	INIT_LIST_HEAD(&ctx->flc_flock);
 230	INIT_LIST_HEAD(&ctx->flc_posix);
 231	INIT_LIST_HEAD(&ctx->flc_lease);
 232
 233	/*
 234	 * Assign the pointer if it's not already assigned. If it is, then
 235	 * free the context we just allocated.
 236	 */
 237	if (cmpxchg(&inode->i_flctx, NULL, ctx)) {
 238		kmem_cache_free(flctx_cache, ctx);
 239		ctx = smp_load_acquire(&inode->i_flctx);
 240	}
 241out:
 242	trace_locks_get_lock_context(inode, type, ctx);
 243	return ctx;
 244}
 245
 246static void
 247locks_dump_ctx_list(struct list_head *list, char *list_type)
 248{
 249	struct file_lock *fl;
 250
 251	list_for_each_entry(fl, list, fl_list) {
 252		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);
 253	}
 
 254}
 255
 256static void
 257locks_check_ctx_lists(struct inode *inode)
 258{
 259	struct file_lock_context *ctx = inode->i_flctx;
 260
 261	if (unlikely(!list_empty(&ctx->flc_flock) ||
 262		     !list_empty(&ctx->flc_posix) ||
 263		     !list_empty(&ctx->flc_lease))) {
 264		pr_warn("Leaked locks on dev=0x%x:0x%x ino=0x%lx:\n",
 265			MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev),
 266			inode->i_ino);
 267		locks_dump_ctx_list(&ctx->flc_flock, "FLOCK");
 268		locks_dump_ctx_list(&ctx->flc_posix, "POSIX");
 269		locks_dump_ctx_list(&ctx->flc_lease, "LEASE");
 270	}
 271}
 272
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 273void
 274locks_free_lock_context(struct inode *inode)
 275{
 276	struct file_lock_context *ctx = inode->i_flctx;
 277
 278	if (unlikely(ctx)) {
 279		locks_check_ctx_lists(inode);
 280		kmem_cache_free(flctx_cache, ctx);
 281	}
 282}
 283
 284static void locks_init_lock_heads(struct file_lock *fl)
 285{
 286	INIT_HLIST_NODE(&fl->fl_link);
 287	INIT_LIST_HEAD(&fl->fl_list);
 288	INIT_LIST_HEAD(&fl->fl_block);
 289	init_waitqueue_head(&fl->fl_wait);
 
 290}
 291
 292/* Allocate an empty lock structure. */
 293struct file_lock *locks_alloc_lock(void)
 294{
 295	struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
 296
 297	if (fl)
 298		locks_init_lock_heads(fl);
 299
 300	return fl;
 301}
 302EXPORT_SYMBOL_GPL(locks_alloc_lock);
 303
 
 
 
 
 
 
 
 
 
 
 
 
 304void locks_release_private(struct file_lock *fl)
 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(fl->fl_owner);
 315			fl->fl_owner = NULL;
 316		}
 317		fl->fl_lmops = NULL;
 318	}
 319}
 320EXPORT_SYMBOL_GPL(locks_release_private);
 321
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 322/* Free a lock which is not in use. */
 323void locks_free_lock(struct file_lock *fl)
 324{
 325	BUG_ON(waitqueue_active(&fl->fl_wait));
 326	BUG_ON(!list_empty(&fl->fl_list));
 327	BUG_ON(!list_empty(&fl->fl_block));
 328	BUG_ON(!hlist_unhashed(&fl->fl_link));
 329
 330	locks_release_private(fl);
 331	kmem_cache_free(filelock_cache, fl);
 332}
 333EXPORT_SYMBOL(locks_free_lock);
 334
 
 
 
 
 
 
 
 335static void
 336locks_dispose_list(struct list_head *dispose)
 337{
 338	struct file_lock *fl;
 339
 340	while (!list_empty(dispose)) {
 341		fl = list_first_entry(dispose, struct file_lock, fl_list);
 342		list_del_init(&fl->fl_list);
 343		locks_free_lock(fl);
 
 
 
 344	}
 345}
 346
 347void locks_init_lock(struct file_lock *fl)
 348{
 349	memset(fl, 0, sizeof(struct file_lock));
 350	locks_init_lock_heads(fl);
 351}
 352
 353EXPORT_SYMBOL(locks_init_lock);
 354
 
 
 
 
 
 
 
 355/*
 356 * Initialize a new lock from an existing file_lock structure.
 357 */
 358void locks_copy_conflock(struct file_lock *new, struct file_lock *fl)
 359{
 360	new->fl_owner = fl->fl_owner;
 361	new->fl_pid = fl->fl_pid;
 362	new->fl_file = NULL;
 363	new->fl_flags = fl->fl_flags;
 364	new->fl_type = fl->fl_type;
 365	new->fl_start = fl->fl_start;
 366	new->fl_end = fl->fl_end;
 367	new->fl_lmops = fl->fl_lmops;
 368	new->fl_ops = NULL;
 369
 370	if (fl->fl_lmops) {
 371		if (fl->fl_lmops->lm_get_owner)
 372			fl->fl_lmops->lm_get_owner(fl->fl_owner);
 373	}
 374}
 375EXPORT_SYMBOL(locks_copy_conflock);
 376
 377void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
 378{
 379	/* "new" must be a freshly-initialized lock */
 380	WARN_ON_ONCE(new->fl_ops);
 381
 382	locks_copy_conflock(new, fl);
 383
 384	new->fl_file = fl->fl_file;
 385	new->fl_ops = fl->fl_ops;
 386
 387	if (fl->fl_ops) {
 388		if (fl->fl_ops->fl_copy_lock)
 389			fl->fl_ops->fl_copy_lock(new, fl);
 390	}
 391}
 392
 393EXPORT_SYMBOL(locks_copy_lock);
 394
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 395static inline int flock_translate_cmd(int cmd) {
 396	if (cmd & LOCK_MAND)
 397		return cmd & (LOCK_MAND | LOCK_RW);
 398	switch (cmd) {
 399	case LOCK_SH:
 400		return F_RDLCK;
 401	case LOCK_EX:
 402		return F_WRLCK;
 403	case LOCK_UN:
 404		return F_UNLCK;
 405	}
 406	return -EINVAL;
 407}
 408
 409/* Fill in a file_lock structure with an appropriate FLOCK lock. */
 410static struct file_lock *
 411flock_make_lock(struct file *filp, unsigned int cmd)
 412{
 413	struct file_lock *fl;
 414	int type = flock_translate_cmd(cmd);
 415
 416	if (type < 0)
 417		return ERR_PTR(type);
 418	
 419	fl = locks_alloc_lock();
 420	if (fl == NULL)
 421		return ERR_PTR(-ENOMEM);
 422
 423	fl->fl_file = filp;
 424	fl->fl_owner = filp;
 425	fl->fl_pid = current->tgid;
 426	fl->fl_flags = FL_FLOCK;
 427	fl->fl_type = type;
 428	fl->fl_end = OFFSET_MAX;
 429	
 430	return fl;
 431}
 432
 433static int assign_type(struct file_lock *fl, long type)
 434{
 435	switch (type) {
 436	case F_RDLCK:
 437	case F_WRLCK:
 438	case F_UNLCK:
 439		fl->fl_type = type;
 440		break;
 441	default:
 442		return -EINVAL;
 443	}
 444	return 0;
 445}
 446
 447static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
 448				 struct flock64 *l)
 449{
 450	switch (l->l_whence) {
 451	case SEEK_SET:
 452		fl->fl_start = 0;
 453		break;
 454	case SEEK_CUR:
 455		fl->fl_start = filp->f_pos;
 456		break;
 457	case SEEK_END:
 458		fl->fl_start = i_size_read(file_inode(filp));
 459		break;
 460	default:
 461		return -EINVAL;
 462	}
 463	if (l->l_start > OFFSET_MAX - fl->fl_start)
 464		return -EOVERFLOW;
 465	fl->fl_start += l->l_start;
 466	if (fl->fl_start < 0)
 467		return -EINVAL;
 468
 469	/* POSIX-1996 leaves the case l->l_len < 0 undefined;
 470	   POSIX-2001 defines it. */
 471	if (l->l_len > 0) {
 472		if (l->l_len - 1 > OFFSET_MAX - fl->fl_start)
 473			return -EOVERFLOW;
 474		fl->fl_end = fl->fl_start + l->l_len - 1;
 475
 476	} else if (l->l_len < 0) {
 477		if (fl->fl_start + l->l_len < 0)
 478			return -EINVAL;
 479		fl->fl_end = fl->fl_start - 1;
 480		fl->fl_start += l->l_len;
 481	} else
 482		fl->fl_end = OFFSET_MAX;
 483
 484	fl->fl_owner = current->files;
 485	fl->fl_pid = current->tgid;
 486	fl->fl_file = filp;
 487	fl->fl_flags = FL_POSIX;
 488	fl->fl_ops = NULL;
 489	fl->fl_lmops = NULL;
 490
 491	return assign_type(fl, l->l_type);
 492}
 493
 494/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
 495 * style lock.
 496 */
 497static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
 498			       struct flock *l)
 499{
 500	struct flock64 ll = {
 501		.l_type = l->l_type,
 502		.l_whence = l->l_whence,
 503		.l_start = l->l_start,
 504		.l_len = l->l_len,
 505	};
 506
 507	return flock64_to_posix_lock(filp, fl, &ll);
 508}
 509
 510/* default lease lock manager operations */
 511static bool
 512lease_break_callback(struct file_lock *fl)
 513{
 514	kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
 515	return false;
 516}
 517
 518static void
 519lease_setup(struct file_lock *fl, void **priv)
 520{
 521	struct file *filp = fl->fl_file;
 522	struct fasync_struct *fa = *priv;
 523
 524	/*
 525	 * fasync_insert_entry() returns the old entry if any. If there was no
 526	 * old entry, then it used "priv" and inserted it into the fasync list.
 527	 * Clear the pointer to indicate that it shouldn't be freed.
 528	 */
 529	if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa))
 530		*priv = NULL;
 531
 532	__f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
 533}
 534
 535static const struct lock_manager_operations lease_manager_ops = {
 536	.lm_break = lease_break_callback,
 537	.lm_change = lease_modify,
 538	.lm_setup = lease_setup,
 539};
 540
 541/*
 542 * Initialize a lease, use the default lock manager operations
 543 */
 544static int lease_init(struct file *filp, long type, struct file_lock *fl)
 545 {
 546	if (assign_type(fl, type) != 0)
 547		return -EINVAL;
 548
 549	fl->fl_owner = filp;
 550	fl->fl_pid = current->tgid;
 551
 552	fl->fl_file = filp;
 553	fl->fl_flags = FL_LEASE;
 554	fl->fl_start = 0;
 555	fl->fl_end = OFFSET_MAX;
 556	fl->fl_ops = NULL;
 557	fl->fl_lmops = &lease_manager_ops;
 558	return 0;
 559}
 560
 561/* Allocate a file_lock initialised to this type of lease */
 562static struct file_lock *lease_alloc(struct file *filp, long type)
 563{
 564	struct file_lock *fl = locks_alloc_lock();
 565	int error = -ENOMEM;
 566
 567	if (fl == NULL)
 568		return ERR_PTR(error);
 569
 570	error = lease_init(filp, type, fl);
 571	if (error) {
 572		locks_free_lock(fl);
 573		return ERR_PTR(error);
 574	}
 575	return fl;
 576}
 577
 578/* Check if two locks overlap each other.
 579 */
 580static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
 581{
 582	return ((fl1->fl_end >= fl2->fl_start) &&
 583		(fl2->fl_end >= fl1->fl_start));
 584}
 585
 586/*
 587 * Check whether two locks have the same owner.
 588 */
 589static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
 590{
 591	if (fl1->fl_lmops && fl1->fl_lmops->lm_compare_owner)
 592		return fl2->fl_lmops == fl1->fl_lmops &&
 593			fl1->fl_lmops->lm_compare_owner(fl1, fl2);
 594	return fl1->fl_owner == fl2->fl_owner;
 595}
 596
 597/* Must be called with the flc_lock held! */
 598static void locks_insert_global_locks(struct file_lock *fl)
 599{
 600	struct file_lock_list_struct *fll = this_cpu_ptr(&file_lock_list);
 601
 602	percpu_rwsem_assert_held(&file_rwsem);
 603
 604	spin_lock(&fll->lock);
 605	fl->fl_link_cpu = smp_processor_id();
 606	hlist_add_head(&fl->fl_link, &fll->hlist);
 607	spin_unlock(&fll->lock);
 608}
 609
 610/* Must be called with the flc_lock held! */
 611static void locks_delete_global_locks(struct file_lock *fl)
 612{
 613	struct file_lock_list_struct *fll;
 614
 615	percpu_rwsem_assert_held(&file_rwsem);
 616
 617	/*
 618	 * Avoid taking lock if already unhashed. This is safe since this check
 619	 * is done while holding the flc_lock, and new insertions into the list
 620	 * also require that it be held.
 621	 */
 622	if (hlist_unhashed(&fl->fl_link))
 623		return;
 624
 625	fll = per_cpu_ptr(&file_lock_list, fl->fl_link_cpu);
 626	spin_lock(&fll->lock);
 627	hlist_del_init(&fl->fl_link);
 628	spin_unlock(&fll->lock);
 629}
 630
 631static unsigned long
 632posix_owner_key(struct file_lock *fl)
 633{
 634	if (fl->fl_lmops && fl->fl_lmops->lm_owner_key)
 635		return fl->fl_lmops->lm_owner_key(fl);
 636	return (unsigned long)fl->fl_owner;
 637}
 638
 639static void locks_insert_global_blocked(struct file_lock *waiter)
 640{
 641	lockdep_assert_held(&blocked_lock_lock);
 642
 643	hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter));
 644}
 645
 646static void locks_delete_global_blocked(struct file_lock *waiter)
 647{
 648	lockdep_assert_held(&blocked_lock_lock);
 649
 650	hash_del(&waiter->fl_link);
 651}
 652
 653/* Remove waiter from blocker's block list.
 654 * When blocker ends up pointing to itself then the list is empty.
 655 *
 656 * Must be called with blocked_lock_lock held.
 657 */
 658static void __locks_delete_block(struct file_lock *waiter)
 659{
 660	locks_delete_global_blocked(waiter);
 661	list_del_init(&waiter->fl_block);
 662	waiter->fl_next = NULL;
 663}
 664
 665static void locks_delete_block(struct file_lock *waiter)
 666{
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 667	spin_lock(&blocked_lock_lock);
 668	__locks_delete_block(waiter);
 
 
 
 
 
 
 
 
 
 669	spin_unlock(&blocked_lock_lock);
 
 
 
 
 
 
 
 
 
 
 
 
 670}
 
 671
 672/* Insert waiter into blocker's block list.
 673 * We use a circular list so that processes can be easily woken up in
 674 * the order they blocked. The documentation doesn't require this but
 675 * it seems like the reasonable thing to do.
 676 *
 677 * Must be called with both the flc_lock and blocked_lock_lock held. The
 678 * fl_block list itself is protected by the blocked_lock_lock, but by ensuring
 679 * that the flc_lock is also held on insertions we can avoid taking the
 680 * blocked_lock_lock in some cases when we see that the fl_block list is empty.
 681 */
 682static void __locks_insert_block(struct file_lock *blocker,
 683					struct file_lock *waiter)
 684{
 685	BUG_ON(!list_empty(&waiter->fl_block));
 686	waiter->fl_next = blocker;
 687	list_add_tail(&waiter->fl_block, &blocker->fl_block);
 688	if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 689		locks_insert_global_blocked(waiter);
 
 
 
 
 
 
 690}
 691
 692/* Must be called with flc_lock held. */
 693static void locks_insert_block(struct file_lock *blocker,
 694					struct file_lock *waiter)
 
 
 695{
 696	spin_lock(&blocked_lock_lock);
 697	__locks_insert_block(blocker, waiter);
 698	spin_unlock(&blocked_lock_lock);
 699}
 700
 701/*
 702 * Wake up processes blocked waiting for blocker.
 703 *
 704 * Must be called with the inode->flc_lock held!
 705 */
 706static void locks_wake_up_blocks(struct file_lock *blocker)
 707{
 708	/*
 709	 * Avoid taking global lock if list is empty. This is safe since new
 710	 * blocked requests are only added to the list under the flc_lock, and
 711	 * the flc_lock is always held here. Note that removal from the fl_block
 712	 * list does not require the flc_lock, so we must recheck list_empty()
 713	 * after acquiring the blocked_lock_lock.
 714	 */
 715	if (list_empty(&blocker->fl_block))
 716		return;
 717
 718	spin_lock(&blocked_lock_lock);
 719	while (!list_empty(&blocker->fl_block)) {
 720		struct file_lock *waiter;
 721
 722		waiter = list_first_entry(&blocker->fl_block,
 723				struct file_lock, fl_block);
 724		__locks_delete_block(waiter);
 725		if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
 726			waiter->fl_lmops->lm_notify(waiter);
 727		else
 728			wake_up(&waiter->fl_wait);
 729	}
 730	spin_unlock(&blocked_lock_lock);
 731}
 732
 733static void
 734locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before)
 735{
 736	fl->fl_nspid = get_pid(task_tgid(current));
 737	list_add_tail(&fl->fl_list, before);
 738	locks_insert_global_locks(fl);
 739}
 740
 741static void
 742locks_unlink_lock_ctx(struct file_lock *fl)
 743{
 744	locks_delete_global_locks(fl);
 745	list_del_init(&fl->fl_list);
 746	if (fl->fl_nspid) {
 747		put_pid(fl->fl_nspid);
 748		fl->fl_nspid = NULL;
 749	}
 750	locks_wake_up_blocks(fl);
 751}
 752
 753static void
 754locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose)
 755{
 756	locks_unlink_lock_ctx(fl);
 757	if (dispose)
 758		list_add(&fl->fl_list, dispose);
 759	else
 760		locks_free_lock(fl);
 761}
 762
 763/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
 764 * checks for shared/exclusive status of overlapping locks.
 765 */
 766static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
 
 767{
 768	if (sys_fl->fl_type == F_WRLCK)
 769		return 1;
 770	if (caller_fl->fl_type == F_WRLCK)
 771		return 1;
 772	return 0;
 773}
 774
 775/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
 776 * checking before calling the locks_conflict().
 777 */
 778static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
 
 779{
 
 
 
 780	/* POSIX locks owned by the same process do not conflict with
 781	 * each other.
 782	 */
 783	if (posix_same_owner(caller_fl, sys_fl))
 784		return (0);
 785
 786	/* Check whether they overlap */
 787	if (!locks_overlap(caller_fl, sys_fl))
 788		return 0;
 
 
 
 789
 790	return (locks_conflict(caller_fl, sys_fl));
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 791}
 792
 793/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
 794 * checking before calling the locks_conflict().
 795 */
 796static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
 
 797{
 798	/* FLOCK locks referring to the same filp do not conflict with
 799	 * each other.
 800	 */
 801	if (caller_fl->fl_file == sys_fl->fl_file)
 802		return (0);
 803	if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
 804		return 0;
 805
 806	return (locks_conflict(caller_fl, sys_fl));
 807}
 808
 809void
 810posix_test_lock(struct file *filp, struct file_lock *fl)
 811{
 812	struct file_lock *cfl;
 813	struct file_lock_context *ctx;
 814	struct inode *inode = locks_inode(filp);
 
 
 815
 816	ctx = smp_load_acquire(&inode->i_flctx);
 817	if (!ctx || list_empty_careful(&ctx->flc_posix)) {
 818		fl->fl_type = F_UNLCK;
 819		return;
 820	}
 821
 
 822	spin_lock(&ctx->flc_lock);
 823	list_for_each_entry(cfl, &ctx->flc_posix, fl_list) {
 824		if (posix_locks_conflict(fl, cfl)) {
 825			locks_copy_conflock(fl, cfl);
 826			if (cfl->fl_nspid)
 827				fl->fl_pid = pid_vnr(cfl->fl_nspid);
 828			goto out;
 
 
 
 
 
 
 829		}
 
 
 830	}
 831	fl->fl_type = F_UNLCK;
 832out:
 833	spin_unlock(&ctx->flc_lock);
 834	return;
 835}
 836EXPORT_SYMBOL(posix_test_lock);
 837
 838/*
 839 * Deadlock detection:
 840 *
 841 * We attempt to detect deadlocks that are due purely to posix file
 842 * locks.
 843 *
 844 * We assume that a task can be waiting for at most one lock at a time.
 845 * So for any acquired lock, the process holding that lock may be
 846 * waiting on at most one other lock.  That lock in turns may be held by
 847 * someone waiting for at most one other lock.  Given a requested lock
 848 * caller_fl which is about to wait for a conflicting lock block_fl, we
 849 * follow this chain of waiters to ensure we are not about to create a
 850 * cycle.
 851 *
 852 * Since we do this before we ever put a process to sleep on a lock, we
 853 * are ensured that there is never a cycle; that is what guarantees that
 854 * the while() loop in posix_locks_deadlock() eventually completes.
 855 *
 856 * Note: the above assumption may not be true when handling lock
 857 * requests from a broken NFS client. It may also fail in the presence
 858 * of tasks (such as posix threads) sharing the same open file table.
 859 * To handle those cases, we just bail out after a few iterations.
 860 *
 861 * For FL_OFDLCK locks, the owner is the filp, not the files_struct.
 862 * Because the owner is not even nominally tied to a thread of
 863 * execution, the deadlock detection below can't reasonably work well. Just
 864 * skip it for those.
 865 *
 866 * In principle, we could do a more limited deadlock detection on FL_OFDLCK
 867 * locks that just checks for the case where two tasks are attempting to
 868 * upgrade from read to write locks on the same inode.
 869 */
 870
 871#define MAX_DEADLK_ITERATIONS 10
 872
 873/* Find a lock that the owner of the given block_fl is blocking on. */
 874static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
 875{
 876	struct file_lock *fl;
 877
 878	hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) {
 879		if (posix_same_owner(fl, block_fl))
 880			return fl->fl_next;
 
 
 
 881	}
 882	return NULL;
 883}
 884
 885/* Must be called with the blocked_lock_lock held! */
 886static int posix_locks_deadlock(struct file_lock *caller_fl,
 887				struct file_lock *block_fl)
 888{
 
 
 889	int i = 0;
 890
 891	lockdep_assert_held(&blocked_lock_lock);
 892
 893	/*
 894	 * This deadlock detector can't reasonably detect deadlocks with
 895	 * FL_OFDLCK locks, since they aren't owned by a process, per-se.
 896	 */
 897	if (IS_OFDLCK(caller_fl))
 898		return 0;
 899
 900	while ((block_fl = what_owner_is_waiting_for(block_fl))) {
 901		if (i++ > MAX_DEADLK_ITERATIONS)
 902			return 0;
 903		if (posix_same_owner(caller_fl, block_fl))
 904			return 1;
 905	}
 906	return 0;
 907}
 908
 909/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
 910 * after any leases, but before any posix locks.
 911 *
 912 * Note that if called with an FL_EXISTS argument, the caller may determine
 913 * whether or not a lock was successfully freed by testing the return
 914 * value for -ENOENT.
 915 */
 916static int flock_lock_inode(struct inode *inode, struct file_lock *request)
 917{
 918	struct file_lock *new_fl = NULL;
 919	struct file_lock *fl;
 920	struct file_lock_context *ctx;
 921	int error = 0;
 922	bool found = false;
 923	LIST_HEAD(dispose);
 924
 925	ctx = locks_get_lock_context(inode, request->fl_type);
 926	if (!ctx) {
 927		if (request->fl_type != F_UNLCK)
 928			return -ENOMEM;
 929		return (request->fl_flags & FL_EXISTS) ? -ENOENT : 0;
 930	}
 931
 932	if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
 933		new_fl = locks_alloc_lock();
 934		if (!new_fl)
 935			return -ENOMEM;
 936	}
 937
 938	percpu_down_read_preempt_disable(&file_rwsem);
 939	spin_lock(&ctx->flc_lock);
 940	if (request->fl_flags & FL_ACCESS)
 941		goto find_conflict;
 942
 943	list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
 944		if (request->fl_file != fl->fl_file)
 945			continue;
 946		if (request->fl_type == fl->fl_type)
 947			goto out;
 948		found = true;
 949		locks_delete_lock_ctx(fl, &dispose);
 950		break;
 951	}
 952
 953	if (request->fl_type == F_UNLCK) {
 954		if ((request->fl_flags & FL_EXISTS) && !found)
 955			error = -ENOENT;
 956		goto out;
 957	}
 958
 959find_conflict:
 960	list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
 961		if (!flock_locks_conflict(request, fl))
 962			continue;
 963		error = -EAGAIN;
 964		if (!(request->fl_flags & FL_SLEEP))
 965			goto out;
 966		error = FILE_LOCK_DEFERRED;
 967		locks_insert_block(fl, request);
 968		goto out;
 969	}
 970	if (request->fl_flags & FL_ACCESS)
 971		goto out;
 972	locks_copy_lock(new_fl, request);
 973	locks_insert_lock_ctx(new_fl, &ctx->flc_flock);
 
 974	new_fl = NULL;
 975	error = 0;
 976
 977out:
 978	spin_unlock(&ctx->flc_lock);
 979	percpu_up_read_preempt_enable(&file_rwsem);
 980	if (new_fl)
 981		locks_free_lock(new_fl);
 982	locks_dispose_list(&dispose);
 
 983	return error;
 984}
 985
 986static int posix_lock_inode(struct inode *inode, struct file_lock *request,
 987			    struct file_lock *conflock)
 988{
 989	struct file_lock *fl, *tmp;
 990	struct file_lock *new_fl = NULL;
 991	struct file_lock *new_fl2 = NULL;
 992	struct file_lock *left = NULL;
 993	struct file_lock *right = NULL;
 994	struct file_lock_context *ctx;
 995	int error;
 996	bool added = false;
 997	LIST_HEAD(dispose);
 
 
 998
 999	ctx = locks_get_lock_context(inode, request->fl_type);
1000	if (!ctx)
1001		return (request->fl_type == F_UNLCK) ? 0 : -ENOMEM;
1002
1003	/*
1004	 * We may need two file_lock structures for this operation,
1005	 * so we get them in advance to avoid races.
1006	 *
1007	 * In some cases we can be sure, that no new locks will be needed
1008	 */
1009	if (!(request->fl_flags & FL_ACCESS) &&
1010	    (request->fl_type != F_UNLCK ||
1011	     request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
1012		new_fl = locks_alloc_lock();
1013		new_fl2 = locks_alloc_lock();
1014	}
1015
1016	percpu_down_read_preempt_disable(&file_rwsem);
 
1017	spin_lock(&ctx->flc_lock);
1018	/*
1019	 * New lock request. Walk all POSIX locks and look for conflicts. If
1020	 * there are any, either return error or put the request on the
1021	 * blocker's list of waiters and the global blocked_hash.
1022	 */
1023	if (request->fl_type != F_UNLCK) {
1024		list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1025			if (!posix_locks_conflict(request, fl))
1026				continue;
 
 
 
 
 
 
 
 
 
 
 
1027			if (conflock)
1028				locks_copy_conflock(conflock, fl);
1029			error = -EAGAIN;
1030			if (!(request->fl_flags & FL_SLEEP))
1031				goto out;
1032			/*
1033			 * Deadlock detection and insertion into the blocked
1034			 * locks list must be done while holding the same lock!
1035			 */
1036			error = -EDEADLK;
1037			spin_lock(&blocked_lock_lock);
 
 
 
 
 
1038			if (likely(!posix_locks_deadlock(request, fl))) {
1039				error = FILE_LOCK_DEFERRED;
1040				__locks_insert_block(fl, request);
 
1041			}
1042			spin_unlock(&blocked_lock_lock);
1043			goto out;
1044  		}
1045  	}
1046
1047	/* If we're just looking for a conflict, we're done. */
1048	error = 0;
1049	if (request->fl_flags & FL_ACCESS)
1050		goto out;
1051
1052	/* Find the first old lock with the same owner as the new lock */
1053	list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1054		if (posix_same_owner(request, fl))
1055			break;
1056	}
1057
1058	/* Process locks with this owner. */
1059	list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, fl_list) {
1060		if (!posix_same_owner(request, fl))
1061			break;
1062
1063		/* Detect adjacent or overlapping regions (if same lock type) */
1064		if (request->fl_type == fl->fl_type) {
1065			/* In all comparisons of start vs end, use
1066			 * "start - 1" rather than "end + 1". If end
1067			 * is OFFSET_MAX, end + 1 will become negative.
1068			 */
1069			if (fl->fl_end < request->fl_start - 1)
1070				continue;
1071			/* If the next lock in the list has entirely bigger
1072			 * addresses than the new one, insert the lock here.
1073			 */
1074			if (fl->fl_start - 1 > request->fl_end)
1075				break;
1076
1077			/* If we come here, the new and old lock are of the
1078			 * same type and adjacent or overlapping. Make one
1079			 * lock yielding from the lower start address of both
1080			 * locks to the higher end address.
1081			 */
1082			if (fl->fl_start > request->fl_start)
1083				fl->fl_start = request->fl_start;
1084			else
1085				request->fl_start = fl->fl_start;
1086			if (fl->fl_end < request->fl_end)
1087				fl->fl_end = request->fl_end;
1088			else
1089				request->fl_end = fl->fl_end;
1090			if (added) {
1091				locks_delete_lock_ctx(fl, &dispose);
1092				continue;
1093			}
1094			request = fl;
1095			added = true;
1096		} else {
1097			/* Processing for different lock types is a bit
1098			 * more complex.
1099			 */
1100			if (fl->fl_end < request->fl_start)
1101				continue;
1102			if (fl->fl_start > request->fl_end)
1103				break;
1104			if (request->fl_type == F_UNLCK)
1105				added = true;
1106			if (fl->fl_start < request->fl_start)
1107				left = fl;
1108			/* If the next lock in the list has a higher end
1109			 * address than the new one, insert the new one here.
1110			 */
1111			if (fl->fl_end > request->fl_end) {
1112				right = fl;
1113				break;
1114			}
1115			if (fl->fl_start >= request->fl_start) {
1116				/* The new lock completely replaces an old
1117				 * one (This may happen several times).
1118				 */
1119				if (added) {
1120					locks_delete_lock_ctx(fl, &dispose);
1121					continue;
1122				}
1123				/*
1124				 * Replace the old lock with new_fl, and
1125				 * remove the old one. It's safe to do the
1126				 * insert here since we know that we won't be
1127				 * using new_fl later, and that the lock is
1128				 * just replacing an existing lock.
1129				 */
1130				error = -ENOLCK;
1131				if (!new_fl)
1132					goto out;
1133				locks_copy_lock(new_fl, request);
 
1134				request = new_fl;
1135				new_fl = NULL;
1136				locks_insert_lock_ctx(request, &fl->fl_list);
1137				locks_delete_lock_ctx(fl, &dispose);
 
1138				added = true;
1139			}
1140		}
1141	}
1142
1143	/*
1144	 * The above code only modifies existing locks in case of merging or
1145	 * replacing. If new lock(s) need to be inserted all modifications are
1146	 * done below this, so it's safe yet to bail out.
1147	 */
1148	error = -ENOLCK; /* "no luck" */
1149	if (right && left == right && !new_fl2)
1150		goto out;
1151
1152	error = 0;
1153	if (!added) {
1154		if (request->fl_type == F_UNLCK) {
1155			if (request->fl_flags & FL_EXISTS)
1156				error = -ENOENT;
1157			goto out;
1158		}
1159
1160		if (!new_fl) {
1161			error = -ENOLCK;
1162			goto out;
1163		}
1164		locks_copy_lock(new_fl, request);
1165		locks_insert_lock_ctx(new_fl, &fl->fl_list);
 
1166		fl = new_fl;
1167		new_fl = NULL;
1168	}
1169	if (right) {
1170		if (left == right) {
1171			/* The new lock breaks the old one in two pieces,
1172			 * so we have to use the second new lock.
1173			 */
1174			left = new_fl2;
1175			new_fl2 = NULL;
1176			locks_copy_lock(left, right);
1177			locks_insert_lock_ctx(left, &fl->fl_list);
1178		}
1179		right->fl_start = request->fl_end + 1;
1180		locks_wake_up_blocks(right);
1181	}
1182	if (left) {
1183		left->fl_end = request->fl_start - 1;
1184		locks_wake_up_blocks(left);
1185	}
1186 out:
 
1187	spin_unlock(&ctx->flc_lock);
1188	percpu_up_read_preempt_enable(&file_rwsem);
1189	/*
1190	 * Free any unused locks.
1191	 */
1192	if (new_fl)
1193		locks_free_lock(new_fl);
1194	if (new_fl2)
1195		locks_free_lock(new_fl2);
1196	locks_dispose_list(&dispose);
1197	trace_posix_lock_inode(inode, request, error);
1198
1199	return error;
1200}
1201
1202/**
1203 * posix_lock_file - Apply a POSIX-style lock to a file
1204 * @filp: The file to apply the lock to
1205 * @fl: The lock to be applied
1206 * @conflock: Place to return a copy of the conflicting lock, if found.
1207 *
1208 * Add a POSIX style lock to a file.
1209 * We merge adjacent & overlapping locks whenever possible.
1210 * POSIX locks are sorted by owner task, then by starting address
1211 *
1212 * Note that if called with an FL_EXISTS argument, the caller may determine
1213 * whether or not a lock was successfully freed by testing the return
1214 * value for -ENOENT.
1215 */
1216int posix_lock_file(struct file *filp, struct file_lock *fl,
1217			struct file_lock *conflock)
1218{
1219	return posix_lock_inode(locks_inode(filp), fl, conflock);
1220}
1221EXPORT_SYMBOL(posix_lock_file);
1222
1223/**
1224 * posix_lock_inode_wait - Apply a POSIX-style lock to a file
1225 * @inode: inode of file to which lock request should be applied
1226 * @fl: The lock to be applied
1227 *
1228 * Apply a POSIX style lock request to an inode.
1229 */
1230static int posix_lock_inode_wait(struct inode *inode, struct file_lock *fl)
1231{
1232	int error;
1233	might_sleep ();
1234	for (;;) {
1235		error = posix_lock_inode(inode, fl, NULL);
1236		if (error != FILE_LOCK_DEFERRED)
1237			break;
1238		error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1239		if (!error)
1240			continue;
1241
1242		locks_delete_block(fl);
1243		break;
1244	}
1245	return error;
1246}
1247
1248#ifdef CONFIG_MANDATORY_FILE_LOCKING
1249/**
1250 * locks_mandatory_locked - Check for an active lock
1251 * @file: the file to check
1252 *
1253 * Searches the inode's list of locks to find any POSIX locks which conflict.
1254 * This function is called from locks_verify_locked() only.
1255 */
1256int locks_mandatory_locked(struct file *file)
1257{
1258	int ret;
1259	struct inode *inode = locks_inode(file);
1260	struct file_lock_context *ctx;
1261	struct file_lock *fl;
1262
1263	ctx = smp_load_acquire(&inode->i_flctx);
1264	if (!ctx || list_empty_careful(&ctx->flc_posix))
1265		return 0;
1266
1267	/*
1268	 * Search the lock list for this inode for any POSIX locks.
1269	 */
1270	spin_lock(&ctx->flc_lock);
1271	ret = 0;
1272	list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1273		if (fl->fl_owner != current->files &&
1274		    fl->fl_owner != file) {
1275			ret = -EAGAIN;
1276			break;
1277		}
1278	}
1279	spin_unlock(&ctx->flc_lock);
1280	return ret;
1281}
1282
1283/**
1284 * locks_mandatory_area - Check for a conflicting lock
1285 * @inode:	the file to check
1286 * @filp:       how the file was opened (if it was)
1287 * @start:	first byte in the file to check
1288 * @end:	lastbyte in the file to check
1289 * @type:	%F_WRLCK for a write lock, else %F_RDLCK
1290 *
1291 * Searches the inode's list of locks to find any POSIX locks which conflict.
1292 */
1293int locks_mandatory_area(struct inode *inode, struct file *filp, loff_t start,
1294			 loff_t end, unsigned char type)
1295{
1296	struct file_lock fl;
1297	int error;
1298	bool sleep = false;
1299
1300	locks_init_lock(&fl);
1301	fl.fl_pid = current->tgid;
1302	fl.fl_file = filp;
1303	fl.fl_flags = FL_POSIX | FL_ACCESS;
1304	if (filp && !(filp->f_flags & O_NONBLOCK))
1305		sleep = true;
1306	fl.fl_type = type;
1307	fl.fl_start = start;
1308	fl.fl_end = end;
1309
1310	for (;;) {
1311		if (filp) {
1312			fl.fl_owner = filp;
1313			fl.fl_flags &= ~FL_SLEEP;
1314			error = posix_lock_inode(inode, &fl, NULL);
1315			if (!error)
1316				break;
1317		}
1318
1319		if (sleep)
1320			fl.fl_flags |= FL_SLEEP;
1321		fl.fl_owner = current->files;
1322		error = posix_lock_inode(inode, &fl, NULL);
1323		if (error != FILE_LOCK_DEFERRED)
1324			break;
1325		error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
1326		if (!error) {
1327			/*
1328			 * If we've been sleeping someone might have
1329			 * changed the permissions behind our back.
1330			 */
1331			if (__mandatory_lock(inode))
1332				continue;
1333		}
1334
1335		locks_delete_block(&fl);
1336		break;
1337	}
1338
1339	return error;
1340}
1341
1342EXPORT_SYMBOL(locks_mandatory_area);
1343#endif /* CONFIG_MANDATORY_FILE_LOCKING */
1344
1345static void lease_clear_pending(struct file_lock *fl, int arg)
1346{
1347	switch (arg) {
1348	case F_UNLCK:
1349		fl->fl_flags &= ~FL_UNLOCK_PENDING;
1350		/* fall through: */
1351	case F_RDLCK:
1352		fl->fl_flags &= ~FL_DOWNGRADE_PENDING;
1353	}
1354}
1355
1356/* We already had a lease on this file; just change its type */
1357int lease_modify(struct file_lock *fl, int arg, struct list_head *dispose)
1358{
1359	int error = assign_type(fl, arg);
1360
1361	if (error)
1362		return error;
1363	lease_clear_pending(fl, arg);
1364	locks_wake_up_blocks(fl);
1365	if (arg == F_UNLCK) {
1366		struct file *filp = fl->fl_file;
1367
1368		f_delown(filp);
1369		filp->f_owner.signum = 0;
1370		fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
1371		if (fl->fl_fasync != NULL) {
1372			printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
1373			fl->fl_fasync = NULL;
1374		}
1375		locks_delete_lock_ctx(fl, dispose);
1376	}
1377	return 0;
1378}
1379EXPORT_SYMBOL(lease_modify);
1380
1381static bool past_time(unsigned long then)
1382{
1383	if (!then)
1384		/* 0 is a special value meaning "this never expires": */
1385		return false;
1386	return time_after(jiffies, then);
1387}
1388
1389static void time_out_leases(struct inode *inode, struct list_head *dispose)
1390{
1391	struct file_lock_context *ctx = inode->i_flctx;
1392	struct file_lock *fl, *tmp;
1393
1394	lockdep_assert_held(&ctx->flc_lock);
1395
1396	list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
1397		trace_time_out_leases(inode, fl);
1398		if (past_time(fl->fl_downgrade_time))
1399			lease_modify(fl, F_RDLCK, dispose);
1400		if (past_time(fl->fl_break_time))
1401			lease_modify(fl, F_UNLCK, dispose);
1402	}
1403}
1404
1405static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
1406{
1407	if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT))
1408		return false;
1409	if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE))
 
 
 
1410		return false;
1411	return locks_conflict(breaker, lease);
 
 
 
 
 
 
 
 
 
 
 
 
1412}
1413
1414static bool
1415any_leases_conflict(struct inode *inode, struct file_lock *breaker)
1416{
1417	struct file_lock_context *ctx = inode->i_flctx;
1418	struct file_lock *fl;
1419
1420	lockdep_assert_held(&ctx->flc_lock);
1421
1422	list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1423		if (leases_conflict(fl, breaker))
1424			return true;
1425	}
1426	return false;
1427}
1428
1429/**
1430 *	__break_lease	-	revoke all outstanding leases on file
1431 *	@inode: the inode of the file to return
1432 *	@mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR:
1433 *	    break all leases
1434 *	@type: FL_LEASE: break leases and delegations; FL_DELEG: break
1435 *	    only delegations
1436 *
1437 *	break_lease (inlined for speed) has checked there already is at least
1438 *	some kind of lock (maybe a lease) on this file.  Leases are broken on
1439 *	a call to open() or truncate().  This function can sleep unless you
1440 *	specified %O_NONBLOCK to your open().
1441 */
1442int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
1443{
1444	int error = 0;
1445	struct file_lock_context *ctx;
1446	struct file_lock *new_fl, *fl, *tmp;
1447	unsigned long break_time;
1448	int want_write = (mode & O_ACCMODE) != O_RDONLY;
1449	LIST_HEAD(dispose);
1450
1451	new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1452	if (IS_ERR(new_fl))
1453		return PTR_ERR(new_fl);
1454	new_fl->fl_flags = type;
1455
1456	/* typically we will check that ctx is non-NULL before calling */
1457	ctx = smp_load_acquire(&inode->i_flctx);
1458	if (!ctx) {
1459		WARN_ON_ONCE(1);
1460		return error;
1461	}
1462
1463	percpu_down_read_preempt_disable(&file_rwsem);
1464	spin_lock(&ctx->flc_lock);
1465
1466	time_out_leases(inode, &dispose);
1467
1468	if (!any_leases_conflict(inode, new_fl))
1469		goto out;
1470
1471	break_time = 0;
1472	if (lease_break_time > 0) {
1473		break_time = jiffies + lease_break_time * HZ;
1474		if (break_time == 0)
1475			break_time++;	/* so that 0 means no break time */
1476	}
1477
1478	list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
1479		if (!leases_conflict(fl, new_fl))
1480			continue;
1481		if (want_write) {
1482			if (fl->fl_flags & FL_UNLOCK_PENDING)
1483				continue;
1484			fl->fl_flags |= FL_UNLOCK_PENDING;
1485			fl->fl_break_time = break_time;
1486		} else {
1487			if (lease_breaking(fl))
1488				continue;
1489			fl->fl_flags |= FL_DOWNGRADE_PENDING;
1490			fl->fl_downgrade_time = break_time;
1491		}
1492		if (fl->fl_lmops->lm_break(fl))
1493			locks_delete_lock_ctx(fl, &dispose);
1494	}
1495
1496	if (list_empty(&ctx->flc_lease))
1497		goto out;
1498
1499	if (mode & O_NONBLOCK) {
1500		trace_break_lease_noblock(inode, new_fl);
1501		error = -EWOULDBLOCK;
1502		goto out;
1503	}
1504
1505restart:
1506	fl = list_first_entry(&ctx->flc_lease, struct file_lock, fl_list);
1507	break_time = fl->fl_break_time;
1508	if (break_time != 0)
1509		break_time -= jiffies;
1510	if (break_time == 0)
1511		break_time++;
1512	locks_insert_block(fl, new_fl);
1513	trace_break_lease_block(inode, new_fl);
1514	spin_unlock(&ctx->flc_lock);
1515	percpu_up_read_preempt_enable(&file_rwsem);
1516
1517	locks_dispose_list(&dispose);
1518	error = wait_event_interruptible_timeout(new_fl->fl_wait,
1519						!new_fl->fl_next, break_time);
 
1520
1521	percpu_down_read_preempt_disable(&file_rwsem);
1522	spin_lock(&ctx->flc_lock);
1523	trace_break_lease_unblock(inode, new_fl);
1524	locks_delete_block(new_fl);
1525	if (error >= 0) {
1526		/*
1527		 * Wait for the next conflicting lease that has not been
1528		 * broken yet
1529		 */
1530		if (error == 0)
1531			time_out_leases(inode, &dispose);
1532		if (any_leases_conflict(inode, new_fl))
1533			goto restart;
1534		error = 0;
1535	}
1536out:
1537	spin_unlock(&ctx->flc_lock);
1538	percpu_up_read_preempt_enable(&file_rwsem);
1539	locks_dispose_list(&dispose);
1540	locks_free_lock(new_fl);
 
1541	return error;
1542}
1543
1544EXPORT_SYMBOL(__break_lease);
1545
1546/**
1547 *	lease_get_mtime - get the last modified time of an inode
1548 *	@inode: the inode
1549 *      @time:  pointer to a timespec which will contain the last modified time
1550 *
1551 * This is to force NFS clients to flush their caches for files with
1552 * exclusive leases.  The justification is that if someone has an
1553 * exclusive lease, then they could be modifying it.
1554 */
1555void lease_get_mtime(struct inode *inode, struct timespec *time)
1556{
1557	bool has_lease = false;
1558	struct file_lock_context *ctx;
1559	struct file_lock *fl;
1560
1561	ctx = smp_load_acquire(&inode->i_flctx);
1562	if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1563		spin_lock(&ctx->flc_lock);
1564		fl = list_first_entry_or_null(&ctx->flc_lease,
1565					      struct file_lock, fl_list);
1566		if (fl && (fl->fl_type == F_WRLCK))
1567			has_lease = true;
1568		spin_unlock(&ctx->flc_lock);
1569	}
1570
1571	if (has_lease)
1572		*time = current_time(inode);
1573	else
1574		*time = inode->i_mtime;
1575}
1576
1577EXPORT_SYMBOL(lease_get_mtime);
1578
1579/**
1580 *	fcntl_getlease - Enquire what lease is currently active
1581 *	@filp: the file
1582 *
1583 *	The value returned by this function will be one of
1584 *	(if no lease break is pending):
1585 *
1586 *	%F_RDLCK to indicate a shared lease is held.
1587 *
1588 *	%F_WRLCK to indicate an exclusive lease is held.
1589 *
1590 *	%F_UNLCK to indicate no lease is held.
1591 *
1592 *	(if a lease break is pending):
1593 *
1594 *	%F_RDLCK to indicate an exclusive lease needs to be
1595 *		changed to a shared lease (or removed).
1596 *
1597 *	%F_UNLCK to indicate the lease needs to be removed.
1598 *
1599 *	XXX: sfr & willy disagree over whether F_INPROGRESS
1600 *	should be returned to userspace.
1601 */
1602int fcntl_getlease(struct file *filp)
1603{
1604	struct file_lock *fl;
1605	struct inode *inode = locks_inode(filp);
1606	struct file_lock_context *ctx;
1607	int type = F_UNLCK;
1608	LIST_HEAD(dispose);
1609
1610	ctx = smp_load_acquire(&inode->i_flctx);
1611	if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1612		percpu_down_read_preempt_disable(&file_rwsem);
1613		spin_lock(&ctx->flc_lock);
1614		time_out_leases(inode, &dispose);
1615		list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1616			if (fl->fl_file != filp)
1617				continue;
1618			type = target_leasetype(fl);
1619			break;
1620		}
1621		spin_unlock(&ctx->flc_lock);
1622		percpu_up_read_preempt_enable(&file_rwsem);
1623
1624		locks_dispose_list(&dispose);
1625	}
1626	return type;
1627}
1628
1629/**
1630 * check_conflicting_open - see if the given dentry points to a file that has
1631 * 			    an existing open that would conflict with the
1632 * 			    desired lease.
1633 * @dentry:	dentry to check
1634 * @arg:	type of lease that we're trying to acquire
1635 * @flags:	current lock flags
1636 *
1637 * Check to see if there's an existing open fd on this file that would
1638 * conflict with the lease we're trying to set.
1639 */
1640static int
1641check_conflicting_open(const struct dentry *dentry, const long arg, int flags)
1642{
1643	int ret = 0;
1644	struct inode *inode = dentry->d_inode;
1645
1646	if (flags & FL_LAYOUT)
1647		return 0;
 
 
 
1648
1649	if ((arg == F_RDLCK) &&
1650	    (atomic_read(&d_real_inode(dentry)->i_writecount) > 0))
1651		return -EAGAIN;
 
1652
1653	if ((arg == F_WRLCK) && ((d_count(dentry) > 1) ||
1654	    (atomic_read(&inode->i_count) > 1)))
1655		ret = -EAGAIN;
 
 
 
 
 
 
 
1656
1657	return ret;
 
 
 
 
1658}
1659
1660static int
1661generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **priv)
1662{
1663	struct file_lock *fl, *my_fl = NULL, *lease;
1664	struct dentry *dentry = filp->f_path.dentry;
1665	struct inode *inode = dentry->d_inode;
1666	struct file_lock_context *ctx;
1667	bool is_deleg = (*flp)->fl_flags & FL_DELEG;
1668	int error;
1669	LIST_HEAD(dispose);
1670
1671	lease = *flp;
1672	trace_generic_add_lease(inode, lease);
1673
 
 
 
 
1674	/* Note that arg is never F_UNLCK here */
1675	ctx = locks_get_lock_context(inode, arg);
1676	if (!ctx)
1677		return -ENOMEM;
1678
1679	/*
1680	 * In the delegation case we need mutual exclusion with
1681	 * a number of operations that take the i_mutex.  We trylock
1682	 * because delegations are an optional optimization, and if
1683	 * there's some chance of a conflict--we'd rather not
1684	 * bother, maybe that's a sign this just isn't a good file to
1685	 * hand out a delegation on.
1686	 */
1687	if (is_deleg && !inode_trylock(inode))
1688		return -EAGAIN;
1689
1690	if (is_deleg && arg == F_WRLCK) {
1691		/* Write delegations are not currently supported: */
1692		inode_unlock(inode);
1693		WARN_ON_ONCE(1);
1694		return -EINVAL;
1695	}
1696
1697	percpu_down_read_preempt_disable(&file_rwsem);
1698	spin_lock(&ctx->flc_lock);
1699	time_out_leases(inode, &dispose);
1700	error = check_conflicting_open(dentry, arg, lease->fl_flags);
1701	if (error)
1702		goto out;
1703
1704	/*
1705	 * At this point, we know that if there is an exclusive
1706	 * lease on this file, then we hold it on this filp
1707	 * (otherwise our open of this file would have blocked).
1708	 * And if we are trying to acquire an exclusive lease,
1709	 * then the file is not open by anyone (including us)
1710	 * except for this filp.
1711	 */
1712	error = -EAGAIN;
1713	list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1714		if (fl->fl_file == filp &&
1715		    fl->fl_owner == lease->fl_owner) {
1716			my_fl = fl;
1717			continue;
1718		}
1719
1720		/*
1721		 * No exclusive leases if someone else has a lease on
1722		 * this file:
1723		 */
1724		if (arg == F_WRLCK)
1725			goto out;
1726		/*
1727		 * Modifying our existing lease is OK, but no getting a
1728		 * new lease if someone else is opening for write:
1729		 */
1730		if (fl->fl_flags & FL_UNLOCK_PENDING)
1731			goto out;
1732	}
1733
1734	if (my_fl != NULL) {
1735		lease = my_fl;
1736		error = lease->fl_lmops->lm_change(lease, arg, &dispose);
1737		if (error)
1738			goto out;
1739		goto out_setup;
1740	}
1741
1742	error = -EINVAL;
1743	if (!leases_enable)
1744		goto out;
1745
1746	locks_insert_lock_ctx(lease, &ctx->flc_lease);
1747	/*
1748	 * The check in break_lease() is lockless. It's possible for another
1749	 * open to race in after we did the earlier check for a conflicting
1750	 * open but before the lease was inserted. Check again for a
1751	 * conflicting open and cancel the lease if there is one.
1752	 *
1753	 * We also add a barrier here to ensure that the insertion of the lock
1754	 * precedes these checks.
1755	 */
1756	smp_mb();
1757	error = check_conflicting_open(dentry, arg, lease->fl_flags);
1758	if (error) {
1759		locks_unlink_lock_ctx(lease);
1760		goto out;
1761	}
1762
1763out_setup:
1764	if (lease->fl_lmops->lm_setup)
1765		lease->fl_lmops->lm_setup(lease, priv);
1766out:
1767	spin_unlock(&ctx->flc_lock);
1768	percpu_up_read_preempt_enable(&file_rwsem);
1769	locks_dispose_list(&dispose);
1770	if (is_deleg)
1771		inode_unlock(inode);
1772	if (!error && !my_fl)
1773		*flp = NULL;
1774	return error;
1775}
1776
1777static int generic_delete_lease(struct file *filp, void *owner)
1778{
1779	int error = -EAGAIN;
1780	struct file_lock *fl, *victim = NULL;
1781	struct inode *inode = locks_inode(filp);
1782	struct file_lock_context *ctx;
1783	LIST_HEAD(dispose);
1784
1785	ctx = smp_load_acquire(&inode->i_flctx);
1786	if (!ctx) {
1787		trace_generic_delete_lease(inode, NULL);
1788		return error;
1789	}
1790
1791	percpu_down_read_preempt_disable(&file_rwsem);
1792	spin_lock(&ctx->flc_lock);
1793	list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1794		if (fl->fl_file == filp &&
1795		    fl->fl_owner == owner) {
1796			victim = fl;
1797			break;
1798		}
1799	}
1800	trace_generic_delete_lease(inode, victim);
1801	if (victim)
1802		error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose);
1803	spin_unlock(&ctx->flc_lock);
1804	percpu_up_read_preempt_enable(&file_rwsem);
1805	locks_dispose_list(&dispose);
1806	return error;
1807}
1808
1809/**
1810 *	generic_setlease	-	sets a lease on an open file
1811 *	@filp:	file pointer
1812 *	@arg:	type of lease to obtain
1813 *	@flp:	input - file_lock to use, output - file_lock inserted
1814 *	@priv:	private data for lm_setup (may be NULL if lm_setup
1815 *		doesn't require it)
1816 *
1817 *	The (input) flp->fl_lmops->lm_break function is required
1818 *	by break_lease().
1819 */
1820int generic_setlease(struct file *filp, long arg, struct file_lock **flp,
1821			void **priv)
1822{
1823	struct inode *inode = locks_inode(filp);
1824	int error;
1825
1826	if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE))
1827		return -EACCES;
1828	if (!S_ISREG(inode->i_mode))
1829		return -EINVAL;
1830	error = security_file_lock(filp, arg);
1831	if (error)
1832		return error;
1833
1834	switch (arg) {
1835	case F_UNLCK:
1836		return generic_delete_lease(filp, *priv);
1837	case F_RDLCK:
1838	case F_WRLCK:
1839		if (!(*flp)->fl_lmops->lm_break) {
1840			WARN_ON_ONCE(1);
1841			return -ENOLCK;
1842		}
1843
1844		return generic_add_lease(filp, arg, flp, priv);
1845	default:
1846		return -EINVAL;
1847	}
1848}
1849EXPORT_SYMBOL(generic_setlease);
1850
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1851/**
1852 * vfs_setlease        -       sets a lease on an open file
1853 * @filp:	file pointer
1854 * @arg:	type of lease to obtain
1855 * @lease:	file_lock to use when adding a lease
1856 * @priv:	private info for lm_setup when adding a lease (may be
1857 * 		NULL if lm_setup doesn't require it)
1858 *
1859 * Call this to establish a lease on the file. The "lease" argument is not
1860 * used for F_UNLCK requests and may be NULL. For commands that set or alter
1861 * an existing lease, the (*lease)->fl_lmops->lm_break operation must be set;
1862 * if not, this function will return -ENOLCK (and generate a scary-looking
1863 * stack trace).
1864 *
1865 * The "priv" pointer is passed directly to the lm_setup function as-is. It
1866 * may be NULL if the lm_setup operation doesn't require it.
1867 */
1868int
1869vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv)
1870{
1871	if (filp->f_op->setlease && is_remote_lock(filp))
1872		return filp->f_op->setlease(filp, arg, lease, priv);
1873	else
1874		return generic_setlease(filp, arg, lease, priv);
 
 
 
 
 
 
 
 
1875}
1876EXPORT_SYMBOL_GPL(vfs_setlease);
1877
1878static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
1879{
1880	struct file_lock *fl;
1881	struct fasync_struct *new;
1882	int error;
1883
1884	fl = lease_alloc(filp, arg);
1885	if (IS_ERR(fl))
1886		return PTR_ERR(fl);
1887
1888	new = fasync_alloc();
1889	if (!new) {
1890		locks_free_lock(fl);
1891		return -ENOMEM;
1892	}
1893	new->fa_fd = fd;
1894
1895	error = vfs_setlease(filp, arg, &fl, (void **)&new);
1896	if (fl)
1897		locks_free_lock(fl);
1898	if (new)
1899		fasync_free(new);
1900	return error;
1901}
1902
1903/**
1904 *	fcntl_setlease	-	sets a lease on an open file
1905 *	@fd: open file descriptor
1906 *	@filp: file pointer
1907 *	@arg: type of lease to obtain
1908 *
1909 *	Call this fcntl to establish a lease on the file.
1910 *	Note that you also need to call %F_SETSIG to
1911 *	receive a signal when the lease is broken.
1912 */
1913int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
1914{
1915	if (arg == F_UNLCK)
1916		return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp);
1917	return do_fcntl_add_lease(fd, filp, arg);
1918}
1919
1920/**
1921 * flock_lock_inode_wait - Apply a FLOCK-style lock to a file
1922 * @inode: inode of the file to apply to
1923 * @fl: The lock to be applied
1924 *
1925 * Apply a FLOCK style lock request to an inode.
1926 */
1927static int flock_lock_inode_wait(struct inode *inode, struct file_lock *fl)
1928{
1929	int error;
1930	might_sleep();
1931	for (;;) {
1932		error = flock_lock_inode(inode, fl);
1933		if (error != FILE_LOCK_DEFERRED)
1934			break;
1935		error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
1936		if (!error)
1937			continue;
1938
1939		locks_delete_block(fl);
1940		break;
1941	}
 
1942	return error;
1943}
1944
1945/**
1946 * locks_lock_inode_wait - Apply a lock to an inode
1947 * @inode: inode of the file to apply to
1948 * @fl: The lock to be applied
1949 *
1950 * Apply a POSIX or FLOCK style lock request to an inode.
1951 */
1952int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl)
1953{
1954	int res = 0;
1955	switch (fl->fl_flags & (FL_POSIX|FL_FLOCK)) {
1956		case FL_POSIX:
1957			res = posix_lock_inode_wait(inode, fl);
1958			break;
1959		case FL_FLOCK:
1960			res = flock_lock_inode_wait(inode, fl);
1961			break;
1962		default:
1963			BUG();
1964	}
1965	return res;
1966}
1967EXPORT_SYMBOL(locks_lock_inode_wait);
1968
1969/**
1970 *	sys_flock: - flock() system call.
1971 *	@fd: the file descriptor to lock.
1972 *	@cmd: the type of lock to apply.
1973 *
1974 *	Apply a %FL_FLOCK style lock to an open file descriptor.
1975 *	The @cmd can be one of
1976 *
1977 *	%LOCK_SH -- a shared lock.
1978 *
1979 *	%LOCK_EX -- an exclusive lock.
1980 *
1981 *	%LOCK_UN -- remove an existing lock.
1982 *
1983 *	%LOCK_MAND -- a `mandatory' flock.  This exists to emulate Windows Share Modes.
 
 
 
1984 *
1985 *	%LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
1986 *	processes read and write access respectively.
1987 */
1988SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
1989{
1990	struct fd f = fdget(fd);
1991	struct file_lock *lock;
1992	int can_sleep, unlock;
1993	int error;
1994
1995	error = -EBADF;
1996	if (!f.file)
1997		goto out;
 
 
 
 
 
 
 
 
 
1998
1999	can_sleep = !(cmd & LOCK_NB);
2000	cmd &= ~LOCK_NB;
2001	unlock = (cmd == LOCK_UN);
2002
2003	if (!unlock && !(cmd & LOCK_MAND) &&
2004	    !(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
2005		goto out_putf;
2006
2007	lock = flock_make_lock(f.file, cmd);
2008	if (IS_ERR(lock)) {
2009		error = PTR_ERR(lock);
2010		goto out_putf;
2011	}
2012
2013	if (can_sleep)
2014		lock->fl_flags |= FL_SLEEP;
2015
2016	error = security_file_lock(f.file, lock->fl_type);
 
 
2017	if (error)
2018		goto out_free;
2019
2020	if (f.file->f_op->flock && is_remote_lock(f.file))
2021		error = f.file->f_op->flock(f.file,
2022					  (can_sleep) ? F_SETLKW : F_SETLK,
2023					  lock);
2024	else
2025		error = locks_lock_file_wait(f.file, lock);
2026
2027 out_free:
2028	locks_free_lock(lock);
 
 
 
 
2029
2030 out_putf:
2031	fdput(f);
2032 out:
2033	return error;
2034}
2035
2036/**
2037 * vfs_test_lock - test file byte range lock
2038 * @filp: The file to test lock for
2039 * @fl: The lock to test; also used to hold result
2040 *
2041 * Returns -ERRNO on failure.  Indicates presence of conflicting lock by
2042 * setting conf->fl_type to something other than F_UNLCK.
2043 */
2044int vfs_test_lock(struct file *filp, struct file_lock *fl)
2045{
2046	if (filp->f_op->lock && is_remote_lock(filp))
 
2047		return filp->f_op->lock(filp, F_GETLK, fl);
2048	posix_test_lock(filp, fl);
2049	return 0;
2050}
2051EXPORT_SYMBOL_GPL(vfs_test_lock);
2052
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2053static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
2054{
2055	flock->l_pid = IS_OFDLCK(fl) ? -1 : fl->fl_pid;
2056#if BITS_PER_LONG == 32
2057	/*
2058	 * Make sure we can represent the posix lock via
2059	 * legacy 32bit flock.
2060	 */
2061	if (fl->fl_start > OFFT_OFFSET_MAX)
2062		return -EOVERFLOW;
2063	if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
2064		return -EOVERFLOW;
2065#endif
2066	flock->l_start = fl->fl_start;
2067	flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2068		fl->fl_end - fl->fl_start + 1;
2069	flock->l_whence = 0;
2070	flock->l_type = fl->fl_type;
2071	return 0;
2072}
2073
2074#if BITS_PER_LONG == 32
2075static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
2076{
2077	flock->l_pid = IS_OFDLCK(fl) ? -1 : fl->fl_pid;
2078	flock->l_start = fl->fl_start;
2079	flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
2080		fl->fl_end - fl->fl_start + 1;
2081	flock->l_whence = 0;
2082	flock->l_type = fl->fl_type;
2083}
2084#endif
2085
2086/* Report the first existing lock that would conflict with l.
2087 * This implements the F_GETLK command of fcntl().
2088 */
2089int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock __user *l)
2090{
2091	struct file_lock file_lock;
2092	struct flock flock;
2093	int error;
2094
2095	error = -EFAULT;
2096	if (copy_from_user(&flock, l, sizeof(flock)))
2097		goto out;
2098	error = -EINVAL;
2099	if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
 
2100		goto out;
2101
2102	error = flock_to_posix_lock(filp, &file_lock, &flock);
2103	if (error)
2104		goto out;
2105
2106	if (cmd == F_OFD_GETLK) {
2107		error = -EINVAL;
2108		if (flock.l_pid != 0)
2109			goto out;
2110
2111		cmd = F_GETLK;
2112		file_lock.fl_flags |= FL_OFDLCK;
2113		file_lock.fl_owner = filp;
2114	}
2115
2116	error = vfs_test_lock(filp, &file_lock);
2117	if (error)
2118		goto out;
2119 
2120	flock.l_type = file_lock.fl_type;
2121	if (file_lock.fl_type != F_UNLCK) {
2122		error = posix_lock_to_flock(&flock, &file_lock);
2123		if (error)
2124			goto rel_priv;
2125	}
2126	error = -EFAULT;
2127	if (!copy_to_user(l, &flock, sizeof(flock)))
2128		error = 0;
2129rel_priv:
2130	locks_release_private(&file_lock);
2131out:
 
2132	return error;
2133}
2134
2135/**
2136 * vfs_lock_file - file byte range lock
2137 * @filp: The file to apply the lock to
2138 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
2139 * @fl: The lock to be applied
2140 * @conf: Place to return a copy of the conflicting lock, if found.
2141 *
2142 * A caller that doesn't care about the conflicting lock may pass NULL
2143 * as the final argument.
2144 *
2145 * If the filesystem defines a private ->lock() method, then @conf will
2146 * be left unchanged; so a caller that cares should initialize it to
2147 * some acceptable default.
2148 *
2149 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
2150 * locks, the ->lock() interface may return asynchronously, before the lock has
2151 * been granted or denied by the underlying filesystem, if (and only if)
2152 * lm_grant is set. Callers expecting ->lock() to return asynchronously
2153 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
2154 * the request is for a blocking lock. When ->lock() does return asynchronously,
2155 * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
2156 * request completes.
 
 
2157 * If the request is for non-blocking lock the file system should return
2158 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
2159 * with the result. If the request timed out the callback routine will return a
2160 * nonzero return code and the file system should release the lock. The file
2161 * system is also responsible to keep a corresponding posix lock when it
2162 * grants a lock so the VFS can find out which locks are locally held and do
2163 * the correct lock cleanup when required.
2164 * The underlying filesystem must not drop the kernel lock or call
2165 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
2166 * return code.
2167 */
2168int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
2169{
2170	if (filp->f_op->lock && is_remote_lock(filp))
 
2171		return filp->f_op->lock(filp, cmd, fl);
2172	else
2173		return posix_lock_file(filp, fl, conf);
2174}
2175EXPORT_SYMBOL_GPL(vfs_lock_file);
2176
2177static int do_lock_file_wait(struct file *filp, unsigned int cmd,
2178			     struct file_lock *fl)
2179{
2180	int error;
2181
2182	error = security_file_lock(filp, fl->fl_type);
2183	if (error)
2184		return error;
2185
2186	for (;;) {
2187		error = vfs_lock_file(filp, cmd, fl, NULL);
2188		if (error != FILE_LOCK_DEFERRED)
2189			break;
2190		error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
2191		if (!error)
2192			continue;
2193
2194		locks_delete_block(fl);
2195		break;
2196	}
 
2197
2198	return error;
2199}
2200
2201/* Ensure that fl->fl_file has compatible f_mode for F_SETLK calls */
2202static int
2203check_fmode_for_setlk(struct file_lock *fl)
2204{
2205	switch (fl->fl_type) {
2206	case F_RDLCK:
2207		if (!(fl->fl_file->f_mode & FMODE_READ))
2208			return -EBADF;
2209		break;
2210	case F_WRLCK:
2211		if (!(fl->fl_file->f_mode & FMODE_WRITE))
2212			return -EBADF;
2213	}
2214	return 0;
2215}
2216
2217/* Apply the lock described by l to an open file descriptor.
2218 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2219 */
2220int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
2221		struct flock __user *l)
2222{
2223	struct file_lock *file_lock = locks_alloc_lock();
2224	struct flock flock;
2225	struct inode *inode;
2226	struct file *f;
2227	int error;
2228
2229	if (file_lock == NULL)
2230		return -ENOLCK;
2231
2232	inode = locks_inode(filp);
2233
2234	/*
2235	 * This might block, so we do it before checking the inode.
2236	 */
2237	error = -EFAULT;
2238	if (copy_from_user(&flock, l, sizeof(flock)))
2239		goto out;
2240
2241	/* Don't allow mandatory locks on files that may be memory mapped
2242	 * and shared.
2243	 */
2244	if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
2245		error = -EAGAIN;
2246		goto out;
2247	}
2248
2249	error = flock_to_posix_lock(filp, file_lock, &flock);
2250	if (error)
2251		goto out;
2252
2253	error = check_fmode_for_setlk(file_lock);
2254	if (error)
2255		goto out;
2256
2257	/*
2258	 * If the cmd is requesting file-private locks, then set the
2259	 * FL_OFDLCK flag and override the owner.
2260	 */
2261	switch (cmd) {
2262	case F_OFD_SETLK:
2263		error = -EINVAL;
2264		if (flock.l_pid != 0)
2265			goto out;
2266
2267		cmd = F_SETLK;
2268		file_lock->fl_flags |= FL_OFDLCK;
2269		file_lock->fl_owner = filp;
2270		break;
2271	case F_OFD_SETLKW:
2272		error = -EINVAL;
2273		if (flock.l_pid != 0)
2274			goto out;
2275
2276		cmd = F_SETLKW;
2277		file_lock->fl_flags |= FL_OFDLCK;
2278		file_lock->fl_owner = filp;
2279		/* Fallthrough */
2280	case F_SETLKW:
2281		file_lock->fl_flags |= FL_SLEEP;
2282	}
2283
2284	error = do_lock_file_wait(filp, cmd, file_lock);
2285
2286	/*
2287	 * Attempt to detect a close/fcntl race and recover by releasing the
2288	 * lock that was just acquired. There is no need to do that when we're
 
2289	 * unlocking though, or for OFD locks.
2290	 */
2291	if (!error && file_lock->fl_type != F_UNLCK &&
2292	    !(file_lock->fl_flags & FL_OFDLCK)) {
 
2293		/*
2294		 * We need that spin_lock here - it prevents reordering between
2295		 * update of i_flctx->flc_posix and check for it done in
2296		 * close(). rcu_read_lock() wouldn't do.
2297		 */
2298		spin_lock(&current->files->file_lock);
2299		f = fcheck(fd);
2300		spin_unlock(&current->files->file_lock);
2301		if (f != filp) {
2302			file_lock->fl_type = F_UNLCK;
2303			error = do_lock_file_wait(filp, cmd, file_lock);
2304			WARN_ON_ONCE(error);
2305			error = -EBADF;
2306		}
2307	}
2308out:
2309	trace_fcntl_setlk(inode, file_lock, error);
2310	locks_free_lock(file_lock);
2311	return error;
2312}
2313
2314#if BITS_PER_LONG == 32
2315/* Report the first existing lock that would conflict with l.
2316 * This implements the F_GETLK command of fcntl().
2317 */
2318int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l)
2319{
2320	struct file_lock file_lock;
2321	struct flock64 flock;
2322	int error;
2323
2324	error = -EFAULT;
2325	if (copy_from_user(&flock, l, sizeof(flock)))
2326		goto out;
 
2327	error = -EINVAL;
2328	if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
 
2329		goto out;
2330
2331	error = flock64_to_posix_lock(filp, &file_lock, &flock);
2332	if (error)
2333		goto out;
2334
2335	if (cmd == F_OFD_GETLK) {
2336		error = -EINVAL;
2337		if (flock.l_pid != 0)
2338			goto out;
2339
2340		cmd = F_GETLK64;
2341		file_lock.fl_flags |= FL_OFDLCK;
2342		file_lock.fl_owner = filp;
2343	}
2344
2345	error = vfs_test_lock(filp, &file_lock);
2346	if (error)
2347		goto out;
2348
2349	flock.l_type = file_lock.fl_type;
2350	if (file_lock.fl_type != F_UNLCK)
2351		posix_lock_to_flock64(&flock, &file_lock);
2352
2353	error = -EFAULT;
2354	if (!copy_to_user(l, &flock, sizeof(flock)))
2355		error = 0;
2356
2357	locks_release_private(&file_lock);
2358out:
 
2359	return error;
2360}
2361
2362/* Apply the lock described by l to an open file descriptor.
2363 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
2364 */
2365int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
2366		struct flock64 __user *l)
2367{
2368	struct file_lock *file_lock = locks_alloc_lock();
2369	struct flock64 flock;
2370	struct inode *inode;
2371	struct file *f;
2372	int error;
2373
2374	if (file_lock == NULL)
2375		return -ENOLCK;
2376
2377	/*
2378	 * This might block, so we do it before checking the inode.
2379	 */
2380	error = -EFAULT;
2381	if (copy_from_user(&flock, l, sizeof(flock)))
2382		goto out;
2383
2384	inode = locks_inode(filp);
2385
2386	/* Don't allow mandatory locks on files that may be memory mapped
2387	 * and shared.
2388	 */
2389	if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
2390		error = -EAGAIN;
2391		goto out;
2392	}
2393
2394	error = flock64_to_posix_lock(filp, file_lock, &flock);
2395	if (error)
2396		goto out;
2397
2398	error = check_fmode_for_setlk(file_lock);
2399	if (error)
2400		goto out;
2401
2402	/*
2403	 * If the cmd is requesting file-private locks, then set the
2404	 * FL_OFDLCK flag and override the owner.
2405	 */
2406	switch (cmd) {
2407	case F_OFD_SETLK:
2408		error = -EINVAL;
2409		if (flock.l_pid != 0)
2410			goto out;
2411
2412		cmd = F_SETLK64;
2413		file_lock->fl_flags |= FL_OFDLCK;
2414		file_lock->fl_owner = filp;
2415		break;
2416	case F_OFD_SETLKW:
2417		error = -EINVAL;
2418		if (flock.l_pid != 0)
2419			goto out;
2420
2421		cmd = F_SETLKW64;
2422		file_lock->fl_flags |= FL_OFDLCK;
2423		file_lock->fl_owner = filp;
2424		/* Fallthrough */
2425	case F_SETLKW64:
2426		file_lock->fl_flags |= FL_SLEEP;
2427	}
2428
2429	error = do_lock_file_wait(filp, cmd, file_lock);
2430
2431	/*
2432	 * Attempt to detect a close/fcntl race and recover by releasing the
2433	 * lock that was just acquired. There is no need to do that when we're
 
2434	 * unlocking though, or for OFD locks.
2435	 */
2436	if (!error && file_lock->fl_type != F_UNLCK &&
2437	    !(file_lock->fl_flags & FL_OFDLCK)) {
 
2438		/*
2439		 * We need that spin_lock here - it prevents reordering between
2440		 * update of i_flctx->flc_posix and check for it done in
2441		 * close(). rcu_read_lock() wouldn't do.
2442		 */
2443		spin_lock(&current->files->file_lock);
2444		f = fcheck(fd);
2445		spin_unlock(&current->files->file_lock);
2446		if (f != filp) {
2447			file_lock->fl_type = F_UNLCK;
2448			error = do_lock_file_wait(filp, cmd, file_lock);
2449			WARN_ON_ONCE(error);
2450			error = -EBADF;
2451		}
2452	}
2453out:
2454	locks_free_lock(file_lock);
2455	return error;
2456}
2457#endif /* BITS_PER_LONG == 32 */
2458
2459/*
2460 * This function is called when the file is being removed
2461 * from the task's fd array.  POSIX locks belonging to this task
2462 * are deleted at this time.
2463 */
2464void locks_remove_posix(struct file *filp, fl_owner_t owner)
2465{
2466	int error;
2467	struct inode *inode = locks_inode(filp);
2468	struct file_lock lock;
2469	struct file_lock_context *ctx;
2470
2471	/*
2472	 * If there are no locks held on this file, we don't need to call
2473	 * posix_lock_file().  Another process could be setting a lock on this
2474	 * file at the same time, but we wouldn't remove that lock anyway.
2475	 */
2476	ctx =  smp_load_acquire(&inode->i_flctx);
2477	if (!ctx || list_empty(&ctx->flc_posix))
2478		return;
2479
2480	lock.fl_type = F_UNLCK;
2481	lock.fl_flags = FL_POSIX | FL_CLOSE;
 
2482	lock.fl_start = 0;
2483	lock.fl_end = OFFSET_MAX;
2484	lock.fl_owner = owner;
2485	lock.fl_pid = current->tgid;
2486	lock.fl_file = filp;
2487	lock.fl_ops = NULL;
2488	lock.fl_lmops = NULL;
2489
2490	error = vfs_lock_file(filp, F_SETLK, &lock, NULL);
2491
2492	if (lock.fl_ops && lock.fl_ops->fl_release_private)
2493		lock.fl_ops->fl_release_private(&lock);
2494	trace_locks_remove_posix(inode, &lock, error);
2495}
2496
2497EXPORT_SYMBOL(locks_remove_posix);
2498
2499/* The i_flctx must be valid when calling into here */
2500static void
2501locks_remove_flock(struct file *filp, struct file_lock_context *flctx)
2502{
2503	struct file_lock fl = {
2504		.fl_owner = filp,
2505		.fl_pid = current->tgid,
2506		.fl_file = filp,
2507		.fl_flags = FL_FLOCK,
2508		.fl_type = F_UNLCK,
2509		.fl_end = OFFSET_MAX,
2510	};
2511	struct inode *inode = locks_inode(filp);
2512
2513	if (list_empty(&flctx->flc_flock))
2514		return;
2515
2516	if (filp->f_op->flock && is_remote_lock(filp))
 
 
 
2517		filp->f_op->flock(filp, F_SETLKW, &fl);
2518	else
2519		flock_lock_inode(inode, &fl);
2520
2521	if (fl.fl_ops && fl.fl_ops->fl_release_private)
2522		fl.fl_ops->fl_release_private(&fl);
2523}
2524
2525/* The i_flctx must be valid when calling into here */
2526static void
2527locks_remove_lease(struct file *filp, struct file_lock_context *ctx)
2528{
2529	struct file_lock *fl, *tmp;
2530	LIST_HEAD(dispose);
2531
2532	if (list_empty(&ctx->flc_lease))
2533		return;
2534
2535	percpu_down_read_preempt_disable(&file_rwsem);
2536	spin_lock(&ctx->flc_lock);
2537	list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list)
2538		if (filp == fl->fl_file)
2539			lease_modify(fl, F_UNLCK, &dispose);
2540	spin_unlock(&ctx->flc_lock);
2541	percpu_up_read_preempt_enable(&file_rwsem);
2542
2543	locks_dispose_list(&dispose);
2544}
2545
2546/*
2547 * This function is called on the last close of an open file.
2548 */
2549void locks_remove_file(struct file *filp)
2550{
2551	struct file_lock_context *ctx;
2552
2553	ctx = smp_load_acquire(&locks_inode(filp)->i_flctx);
2554	if (!ctx)
2555		return;
2556
2557	/* remove any OFD locks */
2558	locks_remove_posix(filp, filp);
2559
2560	/* remove flock locks */
2561	locks_remove_flock(filp, ctx);
2562
2563	/* remove any leases */
2564	locks_remove_lease(filp, ctx);
2565}
2566
2567/**
2568 *	posix_unblock_lock - stop waiting for a file lock
2569 *	@waiter: the lock which was waiting
2570 *
2571 *	lockd needs to block waiting for locks.
2572 */
2573int
2574posix_unblock_lock(struct file_lock *waiter)
2575{
2576	int status = 0;
2577
2578	spin_lock(&blocked_lock_lock);
2579	if (waiter->fl_next)
2580		__locks_delete_block(waiter);
2581	else
2582		status = -ENOENT;
2583	spin_unlock(&blocked_lock_lock);
2584	return status;
2585}
2586EXPORT_SYMBOL(posix_unblock_lock);
2587
2588/**
2589 * vfs_cancel_lock - file byte range unblock lock
2590 * @filp: The file to apply the unblock to
2591 * @fl: The lock to be unblocked
2592 *
2593 * Used by lock managers to cancel blocked requests
2594 */
2595int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
2596{
2597	if (filp->f_op->lock && is_remote_lock(filp))
 
2598		return filp->f_op->lock(filp, F_CANCELLK, fl);
2599	return 0;
2600}
2601
2602EXPORT_SYMBOL_GPL(vfs_cancel_lock);
2603
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2604#ifdef CONFIG_PROC_FS
2605#include <linux/proc_fs.h>
2606#include <linux/seq_file.h>
2607
2608struct locks_iterator {
2609	int	li_cpu;
2610	loff_t	li_pos;
2611};
2612
2613static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2614			    loff_t id, char *pfx)
2615{
2616	struct inode *inode = NULL;
2617	unsigned int fl_pid;
 
 
 
2618
2619	if (fl->fl_nspid) {
2620		struct pid_namespace *proc_pidns = file_inode(f->file)->i_sb->s_fs_info;
2621
2622		/* Don't let fl_pid change based on who is reading the file */
2623		fl_pid = pid_nr_ns(fl->fl_nspid, proc_pidns);
 
 
 
 
 
2624
2625		/*
2626		 * If there isn't a fl_pid don't display who is waiting on
2627		 * the lock if we are called from locks_show, or if we are
2628		 * called from __show_fd_info - skip lock entirely
2629		 */
2630		if (fl_pid == 0)
2631			return;
2632	} else
2633		fl_pid = fl->fl_pid;
2634
2635	if (fl->fl_file != NULL)
2636		inode = locks_inode(fl->fl_file);
2637
2638	seq_printf(f, "%lld:%s ", id, pfx);
2639	if (IS_POSIX(fl)) {
2640		if (fl->fl_flags & FL_ACCESS)
2641			seq_puts(f, "ACCESS");
2642		else if (IS_OFDLCK(fl))
2643			seq_puts(f, "OFDLCK");
2644		else
2645			seq_puts(f, "POSIX ");
2646
2647		seq_printf(f, " %s ",
2648			     (inode == NULL) ? "*NOINODE*" :
2649			     mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
2650	} else if (IS_FLOCK(fl)) {
2651		if (fl->fl_type & LOCK_MAND) {
2652			seq_puts(f, "FLOCK  MSNFS     ");
2653		} else {
2654			seq_puts(f, "FLOCK  ADVISORY  ");
2655		}
2656	} else if (IS_LEASE(fl)) {
2657		if (fl->fl_flags & FL_DELEG)
2658			seq_puts(f, "DELEG  ");
2659		else
2660			seq_puts(f, "LEASE  ");
2661
2662		if (lease_breaking(fl))
2663			seq_puts(f, "BREAKING  ");
2664		else if (fl->fl_file)
2665			seq_puts(f, "ACTIVE    ");
2666		else
2667			seq_puts(f, "BREAKER   ");
2668	} else {
2669		seq_puts(f, "UNKNOWN UNKNOWN  ");
2670	}
2671	if (fl->fl_type & LOCK_MAND) {
2672		seq_printf(f, "%s ",
2673			       (fl->fl_type & LOCK_READ)
2674			       ? (fl->fl_type & LOCK_WRITE) ? "RW   " : "READ "
2675			       : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
2676	} else {
2677		seq_printf(f, "%s ",
2678			       (lease_breaking(fl))
2679			       ? (fl->fl_type == F_UNLCK) ? "UNLCK" : "READ "
2680			       : (fl->fl_type == F_WRLCK) ? "WRITE" : "READ ");
2681	}
2682	if (inode) {
2683		/* userspace relies on this representation of dev_t */
2684		seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
2685				MAJOR(inode->i_sb->s_dev),
2686				MINOR(inode->i_sb->s_dev), inode->i_ino);
2687	} else {
2688		seq_printf(f, "%d <none>:0 ", fl_pid);
2689	}
2690	if (IS_POSIX(fl)) {
2691		if (fl->fl_end == OFFSET_MAX)
2692			seq_printf(f, "%Ld EOF\n", fl->fl_start);
2693		else
2694			seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
2695	} else {
2696		seq_puts(f, "0 EOF\n");
2697	}
2698}
2699
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2700static int locks_show(struct seq_file *f, void *v)
2701{
2702	struct locks_iterator *iter = f->private;
2703	struct file_lock *fl, *bfl;
2704	struct pid_namespace *proc_pidns = file_inode(f->file)->i_sb->s_fs_info;
 
2705
2706	fl = hlist_entry(v, struct file_lock, fl_link);
2707
2708	if (fl->fl_nspid && !pid_nr_ns(fl->fl_nspid, proc_pidns))
2709		return 0;
2710
2711	lock_get_status(f, fl, iter->li_pos, "");
 
 
 
 
 
 
 
 
 
2712
2713	list_for_each_entry(bfl, &fl->fl_block, fl_block)
2714		lock_get_status(f, bfl, iter->li_pos, " ->");
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2715
2716	return 0;
2717}
2718
2719static void __show_fd_locks(struct seq_file *f,
2720			struct list_head *head, int *id,
2721			struct file *filp, struct files_struct *files)
2722{
2723	struct file_lock *fl;
2724
2725	list_for_each_entry(fl, head, fl_list) {
2726
2727		if (filp != fl->fl_file)
2728			continue;
2729		if (fl->fl_owner != files &&
2730		    fl->fl_owner != filp)
2731			continue;
2732
2733		(*id)++;
2734		seq_puts(f, "lock:\t");
2735		lock_get_status(f, fl, *id, "");
2736	}
2737}
2738
2739void show_fd_locks(struct seq_file *f,
2740		  struct file *filp, struct files_struct *files)
2741{
2742	struct inode *inode = locks_inode(filp);
2743	struct file_lock_context *ctx;
2744	int id = 0;
2745
2746	ctx = smp_load_acquire(&inode->i_flctx);
2747	if (!ctx)
2748		return;
2749
2750	spin_lock(&ctx->flc_lock);
2751	__show_fd_locks(f, &ctx->flc_flock, &id, filp, files);
2752	__show_fd_locks(f, &ctx->flc_posix, &id, filp, files);
2753	__show_fd_locks(f, &ctx->flc_lease, &id, filp, files);
2754	spin_unlock(&ctx->flc_lock);
2755}
2756
2757static void *locks_start(struct seq_file *f, loff_t *pos)
2758	__acquires(&blocked_lock_lock)
2759{
2760	struct locks_iterator *iter = f->private;
2761
2762	iter->li_pos = *pos + 1;
2763	percpu_down_write(&file_rwsem);
2764	spin_lock(&blocked_lock_lock);
2765	return seq_hlist_start_percpu(&file_lock_list.hlist, &iter->li_cpu, *pos);
2766}
2767
2768static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
2769{
2770	struct locks_iterator *iter = f->private;
2771
2772	++iter->li_pos;
2773	return seq_hlist_next_percpu(v, &file_lock_list.hlist, &iter->li_cpu, pos);
2774}
2775
2776static void locks_stop(struct seq_file *f, void *v)
2777	__releases(&blocked_lock_lock)
2778{
2779	spin_unlock(&blocked_lock_lock);
2780	percpu_up_write(&file_rwsem);
2781}
2782
2783static const struct seq_operations locks_seq_operations = {
2784	.start	= locks_start,
2785	.next	= locks_next,
2786	.stop	= locks_stop,
2787	.show	= locks_show,
2788};
2789
2790static int locks_open(struct inode *inode, struct file *filp)
2791{
2792	return seq_open_private(filp, &locks_seq_operations,
2793					sizeof(struct locks_iterator));
2794}
2795
2796static const struct file_operations proc_locks_operations = {
2797	.open		= locks_open,
2798	.read		= seq_read,
2799	.llseek		= seq_lseek,
2800	.release	= seq_release_private,
2801};
2802
2803static int __init proc_locks_init(void)
2804{
2805	proc_create("locks", 0, NULL, &proc_locks_operations);
 
2806	return 0;
2807}
2808fs_initcall(proc_locks_init);
2809#endif
2810
2811static int __init filelock_init(void)
2812{
2813	int i;
2814
2815	flctx_cache = kmem_cache_create("file_lock_ctx",
2816			sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL);
2817
2818	filelock_cache = kmem_cache_create("file_lock_cache",
2819			sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
2820
 
 
2821
2822	for_each_possible_cpu(i) {
2823		struct file_lock_list_struct *fll = per_cpu_ptr(&file_lock_list, i);
2824
2825		spin_lock_init(&fll->lock);
2826		INIT_HLIST_HEAD(&fll->hlist);
2827	}
2828
 
2829	return 0;
2830}
2831
2832core_initcall(filelock_init);