locks.c 68.7 KB
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/*
 *  linux/fs/locks.c
 *
 *  Provide support for fcntl()'s F_GETLK, F_SETLK, and F_SETLKW calls.
 *  Doug Evans (dje@spiff.uucp), August 07, 1992
 *
 *  Deadlock detection added.
 *  FIXME: one thing isn't handled yet:
 *	- mandatory locks (requires lots of changes elsewhere)
 *  Kelly Carmichael (kelly@[142.24.8.65]), September 17, 1994.
 *
 *  Miscellaneous edits, and a total rewrite of posix_lock_file() code.
 *  Kai Petzke (wpp@marie.physik.tu-berlin.de), 1994
 *  
 *  Converted file_lock_table to a linked list from an array, which eliminates
 *  the limits on how many active file locks are open.
 *  Chad Page (pageone@netcom.com), November 27, 1994
 * 
 *  Removed dependency on file descriptors. dup()'ed file descriptors now
 *  get the same locks as the original file descriptors, and a close() on
 *  any file descriptor removes ALL the locks on the file for the current
 *  process. Since locks still depend on the process id, locks are inherited
 *  after an exec() but not after a fork(). This agrees with POSIX, and both
 *  BSD and SVR4 practice.
 *  Andy Walker (andy@lysaker.kvaerner.no), February 14, 1995
 *
 *  Scrapped free list which is redundant now that we allocate locks
 *  dynamically with kmalloc()/kfree().
 *  Andy Walker (andy@lysaker.kvaerner.no), February 21, 1995
 *
 *  Implemented two lock personalities - FL_FLOCK and FL_POSIX.
 *
 *  FL_POSIX locks are created with calls to fcntl() and lockf() through the
 *  fcntl() system call. They have the semantics described above.
 *
 *  FL_FLOCK locks are created with calls to flock(), through the flock()
 *  system call, which is new. Old C libraries implement flock() via fcntl()
 *  and will continue to use the old, broken implementation.
 *
 *  FL_FLOCK locks follow the 4.4 BSD flock() semantics. They are associated
 *  with a file pointer (filp). As a result they can be shared by a parent
 *  process and its children after a fork(). They are removed when the last
 *  file descriptor referring to the file pointer is closed (unless explicitly
 *  unlocked). 
 *
 *  FL_FLOCK locks never deadlock, an existing lock is always removed before
 *  upgrading from shared to exclusive (or vice versa). When this happens
 *  any processes blocked by the current lock are woken up and allowed to
 *  run before the new lock is applied.
 *  Andy Walker (andy@lysaker.kvaerner.no), June 09, 1995
 *
 *  Removed some race conditions in flock_lock_file(), marked other possible
 *  races. Just grep for FIXME to see them. 
 *  Dmitry Gorodchanin (pgmdsg@ibi.com), February 09, 1996.
 *
 *  Addressed Dmitry's concerns. Deadlock checking no longer recursive.
 *  Lock allocation changed to GFP_ATOMIC as we can't afford to sleep
 *  once we've checked for blocking and deadlocking.
 *  Andy Walker (andy@lysaker.kvaerner.no), April 03, 1996.
 *
 *  Initial implementation of mandatory locks. SunOS turned out to be
 *  a rotten model, so I implemented the "obvious" semantics.
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 *  See 'Documentation/filesystems/mandatory-locking.txt' for details.
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 *  Andy Walker (andy@lysaker.kvaerner.no), April 06, 1996.
 *
 *  Don't allow mandatory locks on mmap()'ed files. Added simple functions to
 *  check if a file has mandatory locks, used by mmap(), open() and creat() to
 *  see if system call should be rejected. Ref. HP-UX/SunOS/Solaris Reference
 *  Manual, Section 2.
 *  Andy Walker (andy@lysaker.kvaerner.no), April 09, 1996.
 *
 *  Tidied up block list handling. Added '/proc/locks' interface.
 *  Andy Walker (andy@lysaker.kvaerner.no), April 24, 1996.
 *
 *  Fixed deadlock condition for pathological code that mixes calls to
 *  flock() and fcntl().
 *  Andy Walker (andy@lysaker.kvaerner.no), April 29, 1996.
 *
 *  Allow only one type of locking scheme (FL_POSIX or FL_FLOCK) to be in use
 *  for a given file at a time. Changed the CONFIG_LOCK_MANDATORY scheme to
 *  guarantee sensible behaviour in the case where file system modules might
 *  be compiled with different options than the kernel itself.
 *  Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
 *
 *  Added a couple of missing wake_up() calls. Thanks to Thomas Meckel
 *  (Thomas.Meckel@mni.fh-giessen.de) for spotting this.
 *  Andy Walker (andy@lysaker.kvaerner.no), May 15, 1996.
 *
 *  Changed FL_POSIX locks to use the block list in the same way as FL_FLOCK
 *  locks. Changed process synchronisation to avoid dereferencing locks that
 *  have already been freed.
 *  Andy Walker (andy@lysaker.kvaerner.no), Sep 21, 1996.
 *
 *  Made the block list a circular list to minimise searching in the list.
 *  Andy Walker (andy@lysaker.kvaerner.no), Sep 25, 1996.
 *
 *  Made mandatory locking a mount option. Default is not to allow mandatory
 *  locking.
 *  Andy Walker (andy@lysaker.kvaerner.no), Oct 04, 1996.
 *
 *  Some adaptations for NFS support.
 *  Olaf Kirch (okir@monad.swb.de), Dec 1996,
 *
 *  Fixed /proc/locks interface so that we can't overrun the buffer we are handed.
 *  Andy Walker (andy@lysaker.kvaerner.no), May 12, 1997.
 *
 *  Use slab allocator instead of kmalloc/kfree.
 *  Use generic list implementation from <linux/list.h>.
 *  Sped up posix_locks_deadlock by only considering blocked locks.
 *  Matthew Wilcox <willy@debian.org>, March, 2000.
 *
 *  Leases and LOCK_MAND
 *  Matthew Wilcox <willy@debian.org>, June, 2000.
 *  Stephen Rothwell <sfr@canb.auug.org.au>, June, 2000.
 */

#include <linux/capability.h>
#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/fs.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/security.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
#include <linux/time.h>
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#include <linux/rcupdate.h>
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#include <linux/pid_namespace.h>
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#include <linux/hashtable.h>
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#include <linux/percpu.h>
#include <linux/lglock.h>
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#define CREATE_TRACE_POINTS
#include <trace/events/filelock.h>

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#include <asm/uaccess.h>

#define IS_POSIX(fl)	(fl->fl_flags & FL_POSIX)
#define IS_FLOCK(fl)	(fl->fl_flags & FL_FLOCK)
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#define IS_LEASE(fl)	(fl->fl_flags & (FL_LEASE|FL_DELEG|FL_LAYOUT))
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#define IS_OFDLCK(fl)	(fl->fl_flags & FL_OFDLCK)
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static bool lease_breaking(struct file_lock *fl)
{
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	return fl->fl_flags & (FL_UNLOCK_PENDING | FL_DOWNGRADE_PENDING);
}

static int target_leasetype(struct file_lock *fl)
{
	if (fl->fl_flags & FL_UNLOCK_PENDING)
		return F_UNLCK;
	if (fl->fl_flags & FL_DOWNGRADE_PENDING)
		return F_RDLCK;
	return fl->fl_type;
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}

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int leases_enable = 1;
int lease_break_time = 45;

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/*
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 * The global file_lock_list is only used for displaying /proc/locks, so we
 * keep a list on each CPU, with each list protected by its own spinlock via
 * the file_lock_lglock. Note that alterations to the list also require that
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 * the relevant flc_lock is held.
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 */
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DEFINE_STATIC_LGLOCK(file_lock_lglock);
static DEFINE_PER_CPU(struct hlist_head, file_lock_list);
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/*
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 * The blocked_hash is used to find POSIX lock loops for deadlock detection.
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 * It is protected by blocked_lock_lock.
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 *
 * We hash locks by lockowner in order to optimize searching for the lock a
 * particular lockowner is waiting on.
 *
 * FIXME: make this value scale via some heuristic? We generally will want more
 * buckets when we have more lockowners holding locks, but that's a little
 * difficult to determine without knowing what the workload will look like.
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 */
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#define BLOCKED_HASH_BITS	7
static DEFINE_HASHTABLE(blocked_hash, BLOCKED_HASH_BITS);
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/*
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 * This lock protects the blocked_hash. Generally, if you're accessing it, you
 * want to be holding this lock.
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 *
 * In addition, it also protects the fl->fl_block list, and the fl->fl_next
 * pointer for file_lock structures that are acting as lock requests (in
 * contrast to those that are acting as records of acquired locks).
 *
 * Note that when we acquire this lock in order to change the above fields,
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 * we often hold the flc_lock as well. In certain cases, when reading the fields
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 * protected by this lock, we can skip acquiring it iff we already hold the
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 * flc_lock.
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 *
 * In particular, adding an entry to the fl_block list requires that you hold
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 * both the flc_lock and the blocked_lock_lock (acquired in that order).
 * Deleting an entry from the list however only requires the file_lock_lock.
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 */
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static DEFINE_SPINLOCK(blocked_lock_lock);
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static struct kmem_cache *flctx_cache __read_mostly;
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static struct kmem_cache *filelock_cache __read_mostly;
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static struct file_lock_context *
locks_get_lock_context(struct inode *inode)
{
	struct file_lock_context *new;

	if (likely(inode->i_flctx))
		goto out;

	new = kmem_cache_alloc(flctx_cache, GFP_KERNEL);
	if (!new)
		goto out;

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	spin_lock_init(&new->flc_lock);
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	INIT_LIST_HEAD(&new->flc_flock);
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	INIT_LIST_HEAD(&new->flc_posix);
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	INIT_LIST_HEAD(&new->flc_lease);
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	/*
	 * Assign the pointer if it's not already assigned. If it is, then
	 * free the context we just allocated.
	 */
	spin_lock(&inode->i_lock);
	if (likely(!inode->i_flctx)) {
		inode->i_flctx = new;
		new = NULL;
	}
	spin_unlock(&inode->i_lock);

	if (new)
		kmem_cache_free(flctx_cache, new);
out:
	return inode->i_flctx;
}

void
locks_free_lock_context(struct file_lock_context *ctx)
{
	if (ctx) {
		WARN_ON_ONCE(!list_empty(&ctx->flc_flock));
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		WARN_ON_ONCE(!list_empty(&ctx->flc_posix));
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		WARN_ON_ONCE(!list_empty(&ctx->flc_lease));
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		kmem_cache_free(flctx_cache, ctx);
	}
}

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static void locks_init_lock_heads(struct file_lock *fl)
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{
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	INIT_HLIST_NODE(&fl->fl_link);
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	INIT_LIST_HEAD(&fl->fl_list);
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	INIT_LIST_HEAD(&fl->fl_block);
	init_waitqueue_head(&fl->fl_wait);
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}

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/* Allocate an empty lock structure. */
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struct file_lock *locks_alloc_lock(void)
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{
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	struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
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	if (fl)
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		locks_init_lock_heads(fl);
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	return fl;
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}
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EXPORT_SYMBOL_GPL(locks_alloc_lock);
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void locks_release_private(struct file_lock *fl)
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{
	if (fl->fl_ops) {
		if (fl->fl_ops->fl_release_private)
			fl->fl_ops->fl_release_private(fl);
		fl->fl_ops = NULL;
	}

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	if (fl->fl_lmops) {
		if (fl->fl_lmops->lm_put_owner)
			fl->fl_lmops->lm_put_owner(fl);
		fl->fl_lmops = NULL;
	}
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}
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EXPORT_SYMBOL_GPL(locks_release_private);
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/* Free a lock which is not in use. */
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void locks_free_lock(struct file_lock *fl)
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{
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	BUG_ON(waitqueue_active(&fl->fl_wait));
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	BUG_ON(!list_empty(&fl->fl_list));
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	BUG_ON(!list_empty(&fl->fl_block));
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	BUG_ON(!hlist_unhashed(&fl->fl_link));
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	locks_release_private(fl);
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	kmem_cache_free(filelock_cache, fl);
}
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EXPORT_SYMBOL(locks_free_lock);
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static void
locks_dispose_list(struct list_head *dispose)
{
	struct file_lock *fl;

	while (!list_empty(dispose)) {
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		fl = list_first_entry(dispose, struct file_lock, fl_list);
		list_del_init(&fl->fl_list);
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		locks_free_lock(fl);
	}
}

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void locks_init_lock(struct file_lock *fl)
{
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	memset(fl, 0, sizeof(struct file_lock));
	locks_init_lock_heads(fl);
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}

EXPORT_SYMBOL(locks_init_lock);

/*
 * Initialize a new lock from an existing file_lock structure.
 */
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void locks_copy_conflock(struct file_lock *new, struct file_lock *fl)
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{
	new->fl_owner = fl->fl_owner;
	new->fl_pid = fl->fl_pid;
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	new->fl_file = NULL;
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	new->fl_flags = fl->fl_flags;
	new->fl_type = fl->fl_type;
	new->fl_start = fl->fl_start;
	new->fl_end = fl->fl_end;
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	new->fl_lmops = fl->fl_lmops;
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	new->fl_ops = NULL;
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	if (fl->fl_lmops) {
		if (fl->fl_lmops->lm_get_owner)
			fl->fl_lmops->lm_get_owner(new, fl);
	}
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}
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EXPORT_SYMBOL(locks_copy_conflock);
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void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
{
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	/* "new" must be a freshly-initialized lock */
	WARN_ON_ONCE(new->fl_ops);
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	locks_copy_conflock(new, fl);
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	new->fl_file = fl->fl_file;
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	new->fl_ops = fl->fl_ops;
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	if (fl->fl_ops) {
		if (fl->fl_ops->fl_copy_lock)
			fl->fl_ops->fl_copy_lock(new, fl);
	}
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}

EXPORT_SYMBOL(locks_copy_lock);

static inline int flock_translate_cmd(int cmd) {
	if (cmd & LOCK_MAND)
		return cmd & (LOCK_MAND | LOCK_RW);
	switch (cmd) {
	case LOCK_SH:
		return F_RDLCK;
	case LOCK_EX:
		return F_WRLCK;
	case LOCK_UN:
		return F_UNLCK;
	}
	return -EINVAL;
}

/* Fill in a file_lock structure with an appropriate FLOCK lock. */
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static struct file_lock *
flock_make_lock(struct file *filp, unsigned int cmd)
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{
	struct file_lock *fl;
	int type = flock_translate_cmd(cmd);
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	if (type < 0)
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		return ERR_PTR(type);
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	fl = locks_alloc_lock();
	if (fl == NULL)
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		return ERR_PTR(-ENOMEM);
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	fl->fl_file = filp;
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	fl->fl_owner = filp;
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	fl->fl_pid = current->tgid;
	fl->fl_flags = FL_FLOCK;
	fl->fl_type = type;
	fl->fl_end = OFFSET_MAX;
	
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	return fl;
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}

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static int assign_type(struct file_lock *fl, long type)
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{
	switch (type) {
	case F_RDLCK:
	case F_WRLCK:
	case F_UNLCK:
		fl->fl_type = type;
		break;
	default:
		return -EINVAL;
	}
	return 0;
}

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static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
				 struct flock64 *l)
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{
	switch (l->l_whence) {
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	case SEEK_SET:
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		fl->fl_start = 0;
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		break;
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	case SEEK_CUR:
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		fl->fl_start = filp->f_pos;
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		break;
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	case SEEK_END:
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		fl->fl_start = i_size_read(file_inode(filp));
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		break;
	default:
		return -EINVAL;
	}
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	if (l->l_start > OFFSET_MAX - fl->fl_start)
		return -EOVERFLOW;
	fl->fl_start += l->l_start;
	if (fl->fl_start < 0)
		return -EINVAL;
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	/* POSIX-1996 leaves the case l->l_len < 0 undefined;
	   POSIX-2001 defines it. */
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	if (l->l_len > 0) {
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		if (l->l_len - 1 > OFFSET_MAX - fl->fl_start)
			return -EOVERFLOW;
		fl->fl_end = fl->fl_start + l->l_len - 1;

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	} else if (l->l_len < 0) {
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		if (fl->fl_start + l->l_len < 0)
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			return -EINVAL;
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		fl->fl_end = fl->fl_start - 1;
		fl->fl_start += l->l_len;
	} else
		fl->fl_end = OFFSET_MAX;

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	fl->fl_owner = current->files;
	fl->fl_pid = current->tgid;
	fl->fl_file = filp;
	fl->fl_flags = FL_POSIX;
	fl->fl_ops = NULL;
	fl->fl_lmops = NULL;

	return assign_type(fl, l->l_type);
}

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/* Verify a "struct flock" and copy it to a "struct file_lock" as a POSIX
 * style lock.
 */
static int flock_to_posix_lock(struct file *filp, struct file_lock *fl,
			       struct flock *l)
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{
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	struct flock64 ll = {
		.l_type = l->l_type,
		.l_whence = l->l_whence,
		.l_start = l->l_start,
		.l_len = l->l_len,
	};

	return flock64_to_posix_lock(filp, fl, &ll);
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}

/* default lease lock manager operations */
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static bool
lease_break_callback(struct file_lock *fl)
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{
	kill_fasync(&fl->fl_fasync, SIGIO, POLL_MSG);
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	return false;
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}

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static void
lease_setup(struct file_lock *fl, void **priv)
{
	struct file *filp = fl->fl_file;
	struct fasync_struct *fa = *priv;

	/*
	 * fasync_insert_entry() returns the old entry if any. If there was no
	 * old entry, then it used "priv" and inserted it into the fasync list.
	 * Clear the pointer to indicate that it shouldn't be freed.
	 */
	if (!fasync_insert_entry(fa->fa_fd, filp, &fl->fl_fasync, fa))
		*priv = NULL;

	__f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
}

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static const struct lock_manager_operations lease_manager_ops = {
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	.lm_break = lease_break_callback,
	.lm_change = lease_modify,
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	.lm_setup = lease_setup,
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};

/*
 * Initialize a lease, use the default lock manager operations
 */
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static int lease_init(struct file *filp, long type, struct file_lock *fl)
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 {
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	if (assign_type(fl, type) != 0)
		return -EINVAL;

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	fl->fl_owner = filp;
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	fl->fl_pid = current->tgid;

	fl->fl_file = filp;
	fl->fl_flags = FL_LEASE;
	fl->fl_start = 0;
	fl->fl_end = OFFSET_MAX;
	fl->fl_ops = NULL;
	fl->fl_lmops = &lease_manager_ops;
	return 0;
}

/* Allocate a file_lock initialised to this type of lease */
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static struct file_lock *lease_alloc(struct file *filp, long type)
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{
	struct file_lock *fl = locks_alloc_lock();
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	int error = -ENOMEM;
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	if (fl == NULL)
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		return ERR_PTR(error);
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	error = lease_init(filp, type, fl);
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	if (error) {
		locks_free_lock(fl);
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		return ERR_PTR(error);
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	}
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	return fl;
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}

/* Check if two locks overlap each other.
 */
static inline int locks_overlap(struct file_lock *fl1, struct file_lock *fl2)
{
	return ((fl1->fl_end >= fl2->fl_start) &&
		(fl2->fl_end >= fl1->fl_start));
}

/*
 * Check whether two locks have the same owner.
 */
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static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
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{
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555
	if (fl1->fl_lmops && fl1->fl_lmops->lm_compare_owner)
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556
		return fl2->fl_lmops == fl1->fl_lmops &&
J
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557
			fl1->fl_lmops->lm_compare_owner(fl1, fl2);
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558 559 560
	return fl1->fl_owner == fl2->fl_owner;
}

561
/* Must be called with the flc_lock held! */
562
static void locks_insert_global_locks(struct file_lock *fl)
563
{
564 565 566 567
	lg_local_lock(&file_lock_lglock);
	fl->fl_link_cpu = smp_processor_id();
	hlist_add_head(&fl->fl_link, this_cpu_ptr(&file_lock_list));
	lg_local_unlock(&file_lock_lglock);
568 569
}

570
/* Must be called with the flc_lock held! */
571
static void locks_delete_global_locks(struct file_lock *fl)
572
{
573 574
	/*
	 * Avoid taking lock if already unhashed. This is safe since this check
575
	 * is done while holding the flc_lock, and new insertions into the list
576 577 578 579 580
	 * also require that it be held.
	 */
	if (hlist_unhashed(&fl->fl_link))
		return;
	lg_local_lock_cpu(&file_lock_lglock, fl->fl_link_cpu);
581
	hlist_del_init(&fl->fl_link);
582
	lg_local_unlock_cpu(&file_lock_lglock, fl->fl_link_cpu);
583 584
}

585 586 587 588 589 590 591 592
static unsigned long
posix_owner_key(struct file_lock *fl)
{
	if (fl->fl_lmops && fl->fl_lmops->lm_owner_key)
		return fl->fl_lmops->lm_owner_key(fl);
	return (unsigned long)fl->fl_owner;
}

593
static void locks_insert_global_blocked(struct file_lock *waiter)
594
{
595
	hash_add(blocked_hash, &waiter->fl_link, posix_owner_key(waiter));
596 597
}

598
static void locks_delete_global_blocked(struct file_lock *waiter)
599
{
600
	hash_del(&waiter->fl_link);
601 602
}

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/* Remove waiter from blocker's block list.
 * When blocker ends up pointing to itself then the list is empty.
605
 *
606
 * Must be called with blocked_lock_lock held.
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607
 */
608
static void __locks_delete_block(struct file_lock *waiter)
L
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609
{
610
	locks_delete_global_blocked(waiter);
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	list_del_init(&waiter->fl_block);
	waiter->fl_next = NULL;
}

615
static void locks_delete_block(struct file_lock *waiter)
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616
{
617
	spin_lock(&blocked_lock_lock);
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618
	__locks_delete_block(waiter);
619
	spin_unlock(&blocked_lock_lock);
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}

/* Insert waiter into blocker's block list.
 * We use a circular list so that processes can be easily woken up in
 * the order they blocked. The documentation doesn't require this but
 * it seems like the reasonable thing to do.
626
 *
627 628 629 630
 * Must be called with both the flc_lock and blocked_lock_lock held. The
 * fl_block list itself is protected by the blocked_lock_lock, but by ensuring
 * that the flc_lock is also held on insertions we can avoid taking the
 * blocked_lock_lock in some cases when we see that the fl_block list is empty.
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631
 */
632 633
static void __locks_insert_block(struct file_lock *blocker,
					struct file_lock *waiter)
L
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634
{
635
	BUG_ON(!list_empty(&waiter->fl_block));
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636
	waiter->fl_next = blocker;
637
	list_add_tail(&waiter->fl_block, &blocker->fl_block);
638
	if (IS_POSIX(blocker) && !IS_OFDLCK(blocker))
639 640 641
		locks_insert_global_blocked(waiter);
}

642
/* Must be called with flc_lock held. */
643 644 645
static void locks_insert_block(struct file_lock *blocker,
					struct file_lock *waiter)
{
646
	spin_lock(&blocked_lock_lock);
647
	__locks_insert_block(blocker, waiter);
648
	spin_unlock(&blocked_lock_lock);
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}

651 652 653
/*
 * Wake up processes blocked waiting for blocker.
 *
654
 * Must be called with the inode->flc_lock held!
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655 656 657
 */
static void locks_wake_up_blocks(struct file_lock *blocker)
{
658 659
	/*
	 * Avoid taking global lock if list is empty. This is safe since new
660 661 662
	 * blocked requests are only added to the list under the flc_lock, and
	 * the flc_lock is always held here. Note that removal from the fl_block
	 * list does not require the flc_lock, so we must recheck list_empty()
663
	 * after acquiring the blocked_lock_lock.
664 665 666 667
	 */
	if (list_empty(&blocker->fl_block))
		return;

668
	spin_lock(&blocked_lock_lock);
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	while (!list_empty(&blocker->fl_block)) {
670 671 672
		struct file_lock *waiter;

		waiter = list_first_entry(&blocker->fl_block,
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				struct file_lock, fl_block);
		__locks_delete_block(waiter);
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675 676
		if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
			waiter->fl_lmops->lm_notify(waiter);
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677 678 679
		else
			wake_up(&waiter->fl_wait);
	}
680
	spin_unlock(&blocked_lock_lock);
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}

683
static void
684
locks_insert_lock_ctx(struct file_lock *fl, struct list_head *before)
685 686 687 688 689 690
{
	fl->fl_nspid = get_pid(task_tgid(current));
	list_add_tail(&fl->fl_list, before);
	locks_insert_global_locks(fl);
}

691
static void
692
locks_unlink_lock_ctx(struct file_lock *fl)
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693
{
694
	locks_delete_global_locks(fl);
695
	list_del_init(&fl->fl_list);
696 697 698 699
	if (fl->fl_nspid) {
		put_pid(fl->fl_nspid);
		fl->fl_nspid = NULL;
	}
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700
	locks_wake_up_blocks(fl);
701 702
}

703
static void
704
locks_delete_lock_ctx(struct file_lock *fl, struct list_head *dispose)
705
{
706
	locks_unlink_lock_ctx(fl);
707
	if (dispose)
708
		list_add(&fl->fl_list, dispose);
709 710
	else
		locks_free_lock(fl);
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711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758
}

/* Determine if lock sys_fl blocks lock caller_fl. Common functionality
 * checks for shared/exclusive status of overlapping locks.
 */
static int locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
{
	if (sys_fl->fl_type == F_WRLCK)
		return 1;
	if (caller_fl->fl_type == F_WRLCK)
		return 1;
	return 0;
}

/* Determine if lock sys_fl blocks lock caller_fl. POSIX specific
 * checking before calling the locks_conflict().
 */
static int posix_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
{
	/* POSIX locks owned by the same process do not conflict with
	 * each other.
	 */
	if (!IS_POSIX(sys_fl) || posix_same_owner(caller_fl, sys_fl))
		return (0);

	/* Check whether they overlap */
	if (!locks_overlap(caller_fl, sys_fl))
		return 0;

	return (locks_conflict(caller_fl, sys_fl));
}

/* Determine if lock sys_fl blocks lock caller_fl. FLOCK specific
 * checking before calling the locks_conflict().
 */
static int flock_locks_conflict(struct file_lock *caller_fl, struct file_lock *sys_fl)
{
	/* FLOCK locks referring to the same filp do not conflict with
	 * each other.
	 */
	if (!IS_FLOCK(sys_fl) || (caller_fl->fl_file == sys_fl->fl_file))
		return (0);
	if ((caller_fl->fl_type & LOCK_MAND) || (sys_fl->fl_type & LOCK_MAND))
		return 0;

	return (locks_conflict(caller_fl, sys_fl));
}

759
void
760
posix_test_lock(struct file *filp, struct file_lock *fl)
L
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761 762
{
	struct file_lock *cfl;
763
	struct file_lock_context *ctx;
764
	struct inode *inode = file_inode(filp);
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766 767 768 769 770 771
	ctx = inode->i_flctx;
	if (!ctx || list_empty_careful(&ctx->flc_posix)) {
		fl->fl_type = F_UNLCK;
		return;
	}

772
	spin_lock(&ctx->flc_lock);
773 774 775 776 777 778 779
	list_for_each_entry(cfl, &ctx->flc_posix, fl_list) {
		if (posix_locks_conflict(fl, cfl)) {
			locks_copy_conflock(fl, cfl);
			if (cfl->fl_nspid)
				fl->fl_pid = pid_vnr(cfl->fl_nspid);
			goto out;
		}
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780
	}
781 782
	fl->fl_type = F_UNLCK;
out:
783
	spin_unlock(&ctx->flc_lock);
784
	return;
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785 786 787
}
EXPORT_SYMBOL(posix_test_lock);

788 789 790 791 792
/*
 * Deadlock detection:
 *
 * We attempt to detect deadlocks that are due purely to posix file
 * locks.
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793
 *
794 795 796 797 798 799 800
 * We assume that a task can be waiting for at most one lock at a time.
 * So for any acquired lock, the process holding that lock may be
 * waiting on at most one other lock.  That lock in turns may be held by
 * someone waiting for at most one other lock.  Given a requested lock
 * caller_fl which is about to wait for a conflicting lock block_fl, we
 * follow this chain of waiters to ensure we are not about to create a
 * cycle.
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801
 *
802 803 804
 * Since we do this before we ever put a process to sleep on a lock, we
 * are ensured that there is never a cycle; that is what guarantees that
 * the while() loop in posix_locks_deadlock() eventually completes.
805
 *
806 807 808 809
 * Note: the above assumption may not be true when handling lock
 * requests from a broken NFS client. It may also fail in the presence
 * of tasks (such as posix threads) sharing the same open file table.
 * To handle those cases, we just bail out after a few iterations.
810
 *
811
 * For FL_OFDLCK locks, the owner is the filp, not the files_struct.
812 813 814 815
 * Because the owner is not even nominally tied to a thread of
 * execution, the deadlock detection below can't reasonably work well. Just
 * skip it for those.
 *
816
 * In principle, we could do a more limited deadlock detection on FL_OFDLCK
817 818
 * locks that just checks for the case where two tasks are attempting to
 * upgrade from read to write locks on the same inode.
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 */
820 821 822

#define MAX_DEADLK_ITERATIONS 10

823 824 825 826 827
/* Find a lock that the owner of the given block_fl is blocking on. */
static struct file_lock *what_owner_is_waiting_for(struct file_lock *block_fl)
{
	struct file_lock *fl;

828
	hash_for_each_possible(blocked_hash, fl, fl_link, posix_owner_key(block_fl)) {
829 830 831 832 833 834
		if (posix_same_owner(fl, block_fl))
			return fl->fl_next;
	}
	return NULL;
}

835
/* Must be called with the blocked_lock_lock held! */
836
static int posix_locks_deadlock(struct file_lock *caller_fl,
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837 838
				struct file_lock *block_fl)
{
839
	int i = 0;
L
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840

841 842
	/*
	 * This deadlock detector can't reasonably detect deadlocks with
843
	 * FL_OFDLCK locks, since they aren't owned by a process, per-se.
844
	 */
845
	if (IS_OFDLCK(caller_fl))
846 847
		return 0;

848 849 850 851 852
	while ((block_fl = what_owner_is_waiting_for(block_fl))) {
		if (i++ > MAX_DEADLK_ITERATIONS)
			return 0;
		if (posix_same_owner(caller_fl, block_fl))
			return 1;
L
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853 854 855 856 857
	}
	return 0;
}

/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
858
 * after any leases, but before any posix locks.
859 860 861 862
 *
 * Note that if called with an FL_EXISTS argument, the caller may determine
 * whether or not a lock was successfully freed by testing the return
 * value for -ENOENT.
L
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863
 */
864
static int flock_lock_file(struct file *filp, struct file_lock *request)
L
Linus Torvalds 已提交
865
{
866
	struct file_lock *new_fl = NULL;
867 868 869
	struct file_lock *fl;
	struct file_lock_context *ctx;
	struct inode *inode = file_inode(filp);
L
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870
	int error = 0;
871
	bool found = false;
872
	LIST_HEAD(dispose);
L
Linus Torvalds 已提交
873

874 875 876 877
	ctx = locks_get_lock_context(inode);
	if (!ctx)
		return -ENOMEM;

878
	if (!(request->fl_flags & FL_ACCESS) && (request->fl_type != F_UNLCK)) {
879
		new_fl = locks_alloc_lock();
880 881
		if (!new_fl)
			return -ENOMEM;
882 883
	}

884
	spin_lock(&ctx->flc_lock);
885 886 887
	if (request->fl_flags & FL_ACCESS)
		goto find_conflict;

888
	list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
L
Linus Torvalds 已提交
889 890
		if (filp != fl->fl_file)
			continue;
891
		if (request->fl_type == fl->fl_type)
L
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892
			goto out;
893
		found = true;
894
		locks_delete_lock_ctx(fl, &dispose);
L
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895 896 897
		break;
	}

898 899 900
	if (request->fl_type == F_UNLCK) {
		if ((request->fl_flags & FL_EXISTS) && !found)
			error = -ENOENT;
901
		goto out;
902
	}
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903 904 905 906 907

	/*
	 * If a higher-priority process was blocked on the old file lock,
	 * give it the opportunity to lock the file.
	 */
908
	if (found) {
909
		spin_unlock(&ctx->flc_lock);
910
		cond_resched();
911
		spin_lock(&ctx->flc_lock);
912
	}
L
Linus Torvalds 已提交
913

914
find_conflict:
915
	list_for_each_entry(fl, &ctx->flc_flock, fl_list) {
916
		if (!flock_locks_conflict(request, fl))
L
Linus Torvalds 已提交
917 918
			continue;
		error = -EAGAIN;
919 920 921 922
		if (!(request->fl_flags & FL_SLEEP))
			goto out;
		error = FILE_LOCK_DEFERRED;
		locks_insert_block(fl, request);
L
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923 924
		goto out;
	}
925 926
	if (request->fl_flags & FL_ACCESS)
		goto out;
927
	locks_copy_lock(new_fl, request);
928
	locks_insert_lock_ctx(new_fl, &ctx->flc_flock);
929
	new_fl = NULL;
930
	error = 0;
L
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931 932

out:
933
	spin_unlock(&ctx->flc_lock);
934 935
	if (new_fl)
		locks_free_lock(new_fl);
936
	locks_dispose_list(&dispose);
L
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937 938 939
	return error;
}

940
static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock)
L
Linus Torvalds 已提交
941
{
942
	struct file_lock *fl, *tmp;
943 944
	struct file_lock *new_fl = NULL;
	struct file_lock *new_fl2 = NULL;
L
Linus Torvalds 已提交
945 946
	struct file_lock *left = NULL;
	struct file_lock *right = NULL;
947
	struct file_lock_context *ctx;
948 949
	int error;
	bool added = false;
950
	LIST_HEAD(dispose);
L
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951

952 953 954 955
	ctx = locks_get_lock_context(inode);
	if (!ctx)
		return -ENOMEM;

L
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956 957 958
	/*
	 * We may need two file_lock structures for this operation,
	 * so we get them in advance to avoid races.
959 960
	 *
	 * In some cases we can be sure, that no new locks will be needed
L
Linus Torvalds 已提交
961
	 */
962 963 964 965 966 967
	if (!(request->fl_flags & FL_ACCESS) &&
	    (request->fl_type != F_UNLCK ||
	     request->fl_start != 0 || request->fl_end != OFFSET_MAX)) {
		new_fl = locks_alloc_lock();
		new_fl2 = locks_alloc_lock();
	}
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968

969
	spin_lock(&ctx->flc_lock);
970 971 972
	/*
	 * New lock request. Walk all POSIX locks and look for conflicts. If
	 * there are any, either return error or put the request on the
973
	 * blocker's list of waiters and the global blocked_hash.
974
	 */
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975
	if (request->fl_type != F_UNLCK) {
976
		list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
L
Linus Torvalds 已提交
977 978 979 980
			if (!IS_POSIX(fl))
				continue;
			if (!posix_locks_conflict(request, fl))
				continue;
981
			if (conflock)
982
				locks_copy_conflock(conflock, fl);
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983 984 985
			error = -EAGAIN;
			if (!(request->fl_flags & FL_SLEEP))
				goto out;
986 987 988 989
			/*
			 * Deadlock detection and insertion into the blocked
			 * locks list must be done while holding the same lock!
			 */
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990
			error = -EDEADLK;
991
			spin_lock(&blocked_lock_lock);
992 993 994 995
			if (likely(!posix_locks_deadlock(request, fl))) {
				error = FILE_LOCK_DEFERRED;
				__locks_insert_block(fl, request);
			}
996
			spin_unlock(&blocked_lock_lock);
L
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			goto out;
  		}
  	}

	/* If we're just looking for a conflict, we're done. */
	error = 0;
	if (request->fl_flags & FL_ACCESS)
		goto out;

1006 1007 1008 1009
	/* Find the first old lock with the same owner as the new lock */
	list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
		if (posix_same_owner(request, fl))
			break;
L
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1010 1011
	}

1012
	/* Process locks with this owner. */
1013 1014 1015 1016 1017
	list_for_each_entry_safe_from(fl, tmp, &ctx->flc_posix, fl_list) {
		if (!posix_same_owner(request, fl))
			break;

		/* Detect adjacent or overlapping regions (if same lock type) */
L
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1018
		if (request->fl_type == fl->fl_type) {
O
Olaf Kirch 已提交
1019 1020 1021 1022
			/* In all comparisons of start vs end, use
			 * "start - 1" rather than "end + 1". If end
			 * is OFFSET_MAX, end + 1 will become negative.
			 */
L
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1023
			if (fl->fl_end < request->fl_start - 1)
1024
				continue;
L
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1025 1026 1027
			/* If the next lock in the list has entirely bigger
			 * addresses than the new one, insert the lock here.
			 */
O
Olaf Kirch 已提交
1028
			if (fl->fl_start - 1 > request->fl_end)
L
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1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044
				break;

			/* If we come here, the new and old lock are of the
			 * same type and adjacent or overlapping. Make one
			 * lock yielding from the lower start address of both
			 * locks to the higher end address.
			 */
			if (fl->fl_start > request->fl_start)
				fl->fl_start = request->fl_start;
			else
				request->fl_start = fl->fl_start;
			if (fl->fl_end < request->fl_end)
				fl->fl_end = request->fl_end;
			else
				request->fl_end = fl->fl_end;
			if (added) {
1045
				locks_delete_lock_ctx(fl, &dispose);
L
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1046 1047 1048
				continue;
			}
			request = fl;
1049
			added = true;
1050
		} else {
L
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1051 1052 1053 1054
			/* Processing for different lock types is a bit
			 * more complex.
			 */
			if (fl->fl_end < request->fl_start)
1055
				continue;
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1056 1057 1058
			if (fl->fl_start > request->fl_end)
				break;
			if (request->fl_type == F_UNLCK)
1059
				added = true;
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1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073
			if (fl->fl_start < request->fl_start)
				left = fl;
			/* If the next lock in the list has a higher end
			 * address than the new one, insert the new one here.
			 */
			if (fl->fl_end > request->fl_end) {
				right = fl;
				break;
			}
			if (fl->fl_start >= request->fl_start) {
				/* The new lock completely replaces an old
				 * one (This may happen several times).
				 */
				if (added) {
1074
					locks_delete_lock_ctx(fl, &dispose);
L
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1075 1076
					continue;
				}
1077 1078 1079 1080 1081 1082
				/*
				 * Replace the old lock with new_fl, and
				 * remove the old one. It's safe to do the
				 * insert here since we know that we won't be
				 * using new_fl later, and that the lock is
				 * just replacing an existing lock.
L
Linus Torvalds 已提交
1083
				 */
1084 1085 1086 1087 1088 1089
				error = -ENOLCK;
				if (!new_fl)
					goto out;
				locks_copy_lock(new_fl, request);
				request = new_fl;
				new_fl = NULL;
1090 1091
				locks_insert_lock_ctx(request, &fl->fl_list);
				locks_delete_lock_ctx(fl, &dispose);
1092
				added = true;
L
Linus Torvalds 已提交
1093 1094 1095 1096
			}
		}
	}

1097
	/*
1098 1099 1100
	 * The above code only modifies existing locks in case of merging or
	 * replacing. If new lock(s) need to be inserted all modifications are
	 * done below this, so it's safe yet to bail out.
1101 1102 1103 1104 1105
	 */
	error = -ENOLCK; /* "no luck" */
	if (right && left == right && !new_fl2)
		goto out;

L
Linus Torvalds 已提交
1106 1107
	error = 0;
	if (!added) {
1108 1109 1110
		if (request->fl_type == F_UNLCK) {
			if (request->fl_flags & FL_EXISTS)
				error = -ENOENT;
L
Linus Torvalds 已提交
1111
			goto out;
1112
		}
1113 1114 1115 1116 1117

		if (!new_fl) {
			error = -ENOLCK;
			goto out;
		}
L
Linus Torvalds 已提交
1118
		locks_copy_lock(new_fl, request);
1119
		locks_insert_lock_ctx(new_fl, &fl->fl_list);
L
Linus Torvalds 已提交
1120 1121 1122 1123 1124 1125 1126 1127 1128 1129
		new_fl = NULL;
	}
	if (right) {
		if (left == right) {
			/* The new lock breaks the old one in two pieces,
			 * so we have to use the second new lock.
			 */
			left = new_fl2;
			new_fl2 = NULL;
			locks_copy_lock(left, right);
1130
			locks_insert_lock_ctx(left, &fl->fl_list);
L
Linus Torvalds 已提交
1131 1132 1133 1134 1135 1136 1137 1138 1139
		}
		right->fl_start = request->fl_end + 1;
		locks_wake_up_blocks(right);
	}
	if (left) {
		left->fl_end = request->fl_start - 1;
		locks_wake_up_blocks(left);
	}
 out:
1140
	spin_unlock(&ctx->flc_lock);
L
Linus Torvalds 已提交
1141 1142 1143 1144 1145 1146 1147
	/*
	 * Free any unused locks.
	 */
	if (new_fl)
		locks_free_lock(new_fl);
	if (new_fl2)
		locks_free_lock(new_fl2);
1148
	locks_dispose_list(&dispose);
L
Linus Torvalds 已提交
1149 1150 1151 1152 1153 1154 1155
	return error;
}

/**
 * posix_lock_file - Apply a POSIX-style lock to a file
 * @filp: The file to apply the lock to
 * @fl: The lock to be applied
1156
 * @conflock: Place to return a copy of the conflicting lock, if found.
L
Linus Torvalds 已提交
1157 1158 1159 1160
 *
 * Add a POSIX style lock to a file.
 * We merge adjacent & overlapping locks whenever possible.
 * POSIX locks are sorted by owner task, then by starting address
1161 1162 1163 1164
 *
 * Note that if called with an FL_EXISTS argument, the caller may determine
 * whether or not a lock was successfully freed by testing the return
 * value for -ENOENT.
L
Linus Torvalds 已提交
1165
 */
1166
int posix_lock_file(struct file *filp, struct file_lock *fl,
1167 1168
			struct file_lock *conflock)
{
A
Al Viro 已提交
1169
	return __posix_lock_file(file_inode(filp), fl, conflock);
L
Linus Torvalds 已提交
1170
}
1171
EXPORT_SYMBOL(posix_lock_file);
L
Linus Torvalds 已提交
1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186

/**
 * posix_lock_file_wait - Apply a POSIX-style lock to a file
 * @filp: The file to apply the lock to
 * @fl: The lock to be applied
 *
 * Add a POSIX style lock to a file.
 * We merge adjacent & overlapping locks whenever possible.
 * POSIX locks are sorted by owner task, then by starting address
 */
int posix_lock_file_wait(struct file *filp, struct file_lock *fl)
{
	int error;
	might_sleep ();
	for (;;) {
1187
		error = posix_lock_file(filp, fl, NULL);
1188
		if (error != FILE_LOCK_DEFERRED)
L
Linus Torvalds 已提交
1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202
			break;
		error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
		if (!error)
			continue;

		locks_delete_block(fl);
		break;
	}
	return error;
}
EXPORT_SYMBOL(posix_lock_file_wait);

/**
 * locks_mandatory_locked - Check for an active lock
1203
 * @file: the file to check
L
Linus Torvalds 已提交
1204 1205 1206 1207
 *
 * Searches the inode's list of locks to find any POSIX locks which conflict.
 * This function is called from locks_verify_locked() only.
 */
1208
int locks_mandatory_locked(struct file *file)
L
Linus Torvalds 已提交
1209
{
1210
	int ret;
1211
	struct inode *inode = file_inode(file);
1212
	struct file_lock_context *ctx;
L
Linus Torvalds 已提交
1213 1214
	struct file_lock *fl;

1215 1216 1217 1218
	ctx = inode->i_flctx;
	if (!ctx || list_empty_careful(&ctx->flc_posix))
		return 0;

L
Linus Torvalds 已提交
1219 1220 1221
	/*
	 * Search the lock list for this inode for any POSIX locks.
	 */
1222
	spin_lock(&ctx->flc_lock);
1223 1224
	ret = 0;
	list_for_each_entry(fl, &ctx->flc_posix, fl_list) {
1225
		if (fl->fl_owner != current->files &&
1226 1227
		    fl->fl_owner != file) {
			ret = -EAGAIN;
L
Linus Torvalds 已提交
1228
			break;
1229
		}
L
Linus Torvalds 已提交
1230
	}
1231
	spin_unlock(&ctx->flc_lock);
1232
	return ret;
L
Linus Torvalds 已提交
1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253
}

/**
 * locks_mandatory_area - Check for a conflicting lock
 * @read_write: %FLOCK_VERIFY_WRITE for exclusive access, %FLOCK_VERIFY_READ
 *		for shared
 * @inode:      the file to check
 * @filp:       how the file was opened (if it was)
 * @offset:     start of area to check
 * @count:      length of area to check
 *
 * Searches the inode's list of locks to find any POSIX locks which conflict.
 * This function is called from rw_verify_area() and
 * locks_verify_truncate().
 */
int locks_mandatory_area(int read_write, struct inode *inode,
			 struct file *filp, loff_t offset,
			 size_t count)
{
	struct file_lock fl;
	int error;
1254
	bool sleep = false;
L
Linus Torvalds 已提交
1255 1256 1257 1258 1259 1260

	locks_init_lock(&fl);
	fl.fl_pid = current->tgid;
	fl.fl_file = filp;
	fl.fl_flags = FL_POSIX | FL_ACCESS;
	if (filp && !(filp->f_flags & O_NONBLOCK))
1261
		sleep = true;
L
Linus Torvalds 已提交
1262 1263 1264 1265 1266
	fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
	fl.fl_start = offset;
	fl.fl_end = offset + count - 1;

	for (;;) {
1267
		if (filp) {
1268
			fl.fl_owner = filp;
1269 1270 1271 1272 1273 1274 1275 1276 1277
			fl.fl_flags &= ~FL_SLEEP;
			error = __posix_lock_file(inode, &fl, NULL);
			if (!error)
				break;
		}

		if (sleep)
			fl.fl_flags |= FL_SLEEP;
		fl.fl_owner = current->files;
1278
		error = __posix_lock_file(inode, &fl, NULL);
1279
		if (error != FILE_LOCK_DEFERRED)
L
Linus Torvalds 已提交
1280 1281 1282 1283 1284 1285 1286
			break;
		error = wait_event_interruptible(fl.fl_wait, !fl.fl_next);
		if (!error) {
			/*
			 * If we've been sleeping someone might have
			 * changed the permissions behind our back.
			 */
1287
			if (__mandatory_lock(inode))
L
Linus Torvalds 已提交
1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299
				continue;
		}

		locks_delete_block(&fl);
		break;
	}

	return error;
}

EXPORT_SYMBOL(locks_mandatory_area);

1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310
static void lease_clear_pending(struct file_lock *fl, int arg)
{
	switch (arg) {
	case F_UNLCK:
		fl->fl_flags &= ~FL_UNLOCK_PENDING;
		/* fall through: */
	case F_RDLCK:
		fl->fl_flags &= ~FL_DOWNGRADE_PENDING;
	}
}

L
Linus Torvalds 已提交
1311
/* We already had a lease on this file; just change its type */
1312
int lease_modify(struct file_lock *fl, int arg, struct list_head *dispose)
L
Linus Torvalds 已提交
1313 1314 1315 1316 1317
{
	int error = assign_type(fl, arg);

	if (error)
		return error;
1318
	lease_clear_pending(fl, arg);
L
Linus Torvalds 已提交
1319
	locks_wake_up_blocks(fl);
1320 1321 1322 1323 1324
	if (arg == F_UNLCK) {
		struct file *filp = fl->fl_file;

		f_delown(filp);
		filp->f_owner.signum = 0;
1325 1326 1327 1328 1329
		fasync_helper(0, fl->fl_file, 0, &fl->fl_fasync);
		if (fl->fl_fasync != NULL) {
			printk(KERN_ERR "locks_delete_lock: fasync == %p\n", fl->fl_fasync);
			fl->fl_fasync = NULL;
		}
1330
		locks_delete_lock_ctx(fl, dispose);
1331
	}
L
Linus Torvalds 已提交
1332 1333 1334 1335
	return 0;
}
EXPORT_SYMBOL(lease_modify);

1336 1337 1338 1339 1340 1341 1342 1343
static bool past_time(unsigned long then)
{
	if (!then)
		/* 0 is a special value meaning "this never expires": */
		return false;
	return time_after(jiffies, then);
}

1344
static void time_out_leases(struct inode *inode, struct list_head *dispose)
L
Linus Torvalds 已提交
1345
{
1346 1347
	struct file_lock_context *ctx = inode->i_flctx;
	struct file_lock *fl, *tmp;
L
Linus Torvalds 已提交
1348

1349
	lockdep_assert_held(&ctx->flc_lock);
1350

1351
	list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list) {
1352
		trace_time_out_leases(inode, fl);
1353
		if (past_time(fl->fl_downgrade_time))
1354
			lease_modify(fl, F_RDLCK, dispose);
1355
		if (past_time(fl->fl_break_time))
1356
			lease_modify(fl, F_UNLCK, dispose);
L
Linus Torvalds 已提交
1357 1358 1359
	}
}

J
J. Bruce Fields 已提交
1360 1361
static bool leases_conflict(struct file_lock *lease, struct file_lock *breaker)
{
C
Christoph Hellwig 已提交
1362 1363
	if ((breaker->fl_flags & FL_LAYOUT) != (lease->fl_flags & FL_LAYOUT))
		return false;
J
J. Bruce Fields 已提交
1364 1365 1366 1367 1368
	if ((breaker->fl_flags & FL_DELEG) && (lease->fl_flags & FL_LEASE))
		return false;
	return locks_conflict(breaker, lease);
}

1369 1370 1371
static bool
any_leases_conflict(struct inode *inode, struct file_lock *breaker)
{
1372
	struct file_lock_context *ctx = inode->i_flctx;
1373 1374
	struct file_lock *fl;

1375
	lockdep_assert_held(&ctx->flc_lock);
1376

1377
	list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1378 1379 1380 1381 1382 1383
		if (leases_conflict(fl, breaker))
			return true;
	}
	return false;
}

L
Linus Torvalds 已提交
1384 1385 1386
/**
 *	__break_lease	-	revoke all outstanding leases on file
 *	@inode: the inode of the file to return
J
J. Bruce Fields 已提交
1387 1388 1389 1390
 *	@mode: O_RDONLY: break only write leases; O_WRONLY or O_RDWR:
 *	    break all leases
 *	@type: FL_LEASE: break leases and delegations; FL_DELEG: break
 *	    only delegations
L
Linus Torvalds 已提交
1391
 *
1392 1393 1394
 *	break_lease (inlined for speed) has checked there already is at least
 *	some kind of lock (maybe a lease) on this file.  Leases are broken on
 *	a call to open() or truncate().  This function can sleep unless you
L
Linus Torvalds 已提交
1395 1396
 *	specified %O_NONBLOCK to your open().
 */
J
J. Bruce Fields 已提交
1397
int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
L
Linus Torvalds 已提交
1398
{
1399
	int error = 0;
1400
	struct file_lock *new_fl;
1401 1402
	struct file_lock_context *ctx = inode->i_flctx;
	struct file_lock *fl;
L
Linus Torvalds 已提交
1403
	unsigned long break_time;
1404
	int want_write = (mode & O_ACCMODE) != O_RDONLY;
1405
	LIST_HEAD(dispose);
L
Linus Torvalds 已提交
1406

1407
	new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
1408 1409
	if (IS_ERR(new_fl))
		return PTR_ERR(new_fl);
J
J. Bruce Fields 已提交
1410
	new_fl->fl_flags = type;
L
Linus Torvalds 已提交
1411

1412 1413 1414 1415 1416 1417
	/* typically we will check that ctx is non-NULL before calling */
	if (!ctx) {
		WARN_ON_ONCE(1);
		return error;
	}

1418
	spin_lock(&ctx->flc_lock);
L
Linus Torvalds 已提交
1419

1420
	time_out_leases(inode, &dispose);
L
Linus Torvalds 已提交
1421

1422
	if (!any_leases_conflict(inode, new_fl))
1423 1424
		goto out;

L
Linus Torvalds 已提交
1425 1426 1427 1428 1429 1430 1431
	break_time = 0;
	if (lease_break_time > 0) {
		break_time = jiffies + lease_break_time * HZ;
		if (break_time == 0)
			break_time++;	/* so that 0 means no break time */
	}

1432
	list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
J
J. Bruce Fields 已提交
1433 1434
		if (!leases_conflict(fl, new_fl))
			continue;
1435 1436 1437 1438
		if (want_write) {
			if (fl->fl_flags & FL_UNLOCK_PENDING)
				continue;
			fl->fl_flags |= FL_UNLOCK_PENDING;
L
Linus Torvalds 已提交
1439
			fl->fl_break_time = break_time;
1440
		} else {
1441
			if (lease_breaking(fl))
1442 1443 1444
				continue;
			fl->fl_flags |= FL_DOWNGRADE_PENDING;
			fl->fl_downgrade_time = break_time;
L
Linus Torvalds 已提交
1445
		}
J
Jeff Layton 已提交
1446
		if (fl->fl_lmops->lm_break(fl))
1447
			locks_delete_lock_ctx(fl, &dispose);
L
Linus Torvalds 已提交
1448 1449
	}

1450
	if (list_empty(&ctx->flc_lease))
J
Jeff Layton 已提交
1451 1452
		goto out;

1453
	if (mode & O_NONBLOCK) {
1454
		trace_break_lease_noblock(inode, new_fl);
L
Linus Torvalds 已提交
1455 1456 1457 1458 1459
		error = -EWOULDBLOCK;
		goto out;
	}

restart:
1460 1461
	fl = list_first_entry(&ctx->flc_lease, struct file_lock, fl_list);
	break_time = fl->fl_break_time;
1462
	if (break_time != 0)
L
Linus Torvalds 已提交
1463
		break_time -= jiffies;
1464 1465
	if (break_time == 0)
		break_time++;
1466
	locks_insert_block(fl, new_fl);
1467
	trace_break_lease_block(inode, new_fl);
1468
	spin_unlock(&ctx->flc_lock);
1469
	locks_dispose_list(&dispose);
1470 1471
	error = wait_event_interruptible_timeout(new_fl->fl_wait,
						!new_fl->fl_next, break_time);
1472
	spin_lock(&ctx->flc_lock);
1473
	trace_break_lease_unblock(inode, new_fl);
1474
	locks_delete_block(new_fl);
L
Linus Torvalds 已提交
1475
	if (error >= 0) {
1476 1477 1478 1479
		/*
		 * Wait for the next conflicting lease that has not been
		 * broken yet
		 */
1480 1481 1482 1483
		if (error == 0)
			time_out_leases(inode, &dispose);
		if (any_leases_conflict(inode, new_fl))
			goto restart;
L
Linus Torvalds 已提交
1484 1485 1486
		error = 0;
	}
out:
1487
	spin_unlock(&ctx->flc_lock);
1488
	locks_dispose_list(&dispose);
1489
	locks_free_lock(new_fl);
L
Linus Torvalds 已提交
1490 1491 1492 1493 1494 1495
	return error;
}

EXPORT_SYMBOL(__break_lease);

/**
1496
 *	lease_get_mtime - get the last modified time of an inode
L
Linus Torvalds 已提交
1497 1498 1499 1500 1501
 *	@inode: the inode
 *      @time:  pointer to a timespec which will contain the last modified time
 *
 * This is to force NFS clients to flush their caches for files with
 * exclusive leases.  The justification is that if someone has an
1502
 * exclusive lease, then they could be modifying it.
L
Linus Torvalds 已提交
1503 1504 1505
 */
void lease_get_mtime(struct inode *inode, struct timespec *time)
{
1506
	bool has_lease = false;
1507 1508
	struct file_lock_context *ctx = inode->i_flctx;
	struct file_lock *fl;
1509

1510
	if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1511
		spin_lock(&ctx->flc_lock);
1512 1513 1514 1515 1516 1517
		if (!list_empty(&ctx->flc_lease)) {
			fl = list_first_entry(&ctx->flc_lease,
						struct file_lock, fl_list);
			if (fl->fl_type == F_WRLCK)
				has_lease = true;
		}
1518
		spin_unlock(&ctx->flc_lock);
1519 1520 1521
	}

	if (has_lease)
L
Linus Torvalds 已提交
1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554
		*time = current_fs_time(inode->i_sb);
	else
		*time = inode->i_mtime;
}

EXPORT_SYMBOL(lease_get_mtime);

/**
 *	fcntl_getlease - Enquire what lease is currently active
 *	@filp: the file
 *
 *	The value returned by this function will be one of
 *	(if no lease break is pending):
 *
 *	%F_RDLCK to indicate a shared lease is held.
 *
 *	%F_WRLCK to indicate an exclusive lease is held.
 *
 *	%F_UNLCK to indicate no lease is held.
 *
 *	(if a lease break is pending):
 *
 *	%F_RDLCK to indicate an exclusive lease needs to be
 *		changed to a shared lease (or removed).
 *
 *	%F_UNLCK to indicate the lease needs to be removed.
 *
 *	XXX: sfr & willy disagree over whether F_INPROGRESS
 *	should be returned to userspace.
 */
int fcntl_getlease(struct file *filp)
{
	struct file_lock *fl;
1555
	struct inode *inode = file_inode(filp);
1556
	struct file_lock_context *ctx = inode->i_flctx;
L
Linus Torvalds 已提交
1557
	int type = F_UNLCK;
1558
	LIST_HEAD(dispose);
L
Linus Torvalds 已提交
1559

1560
	if (ctx && !list_empty_careful(&ctx->flc_lease)) {
1561
		spin_lock(&ctx->flc_lock);
1562 1563 1564 1565
		time_out_leases(file_inode(filp), &dispose);
		list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
			if (fl->fl_file != filp)
				continue;
1566
			type = target_leasetype(fl);
L
Linus Torvalds 已提交
1567 1568
			break;
		}
1569
		spin_unlock(&ctx->flc_lock);
1570
		locks_dispose_list(&dispose);
L
Linus Torvalds 已提交
1571 1572 1573 1574
	}
	return type;
}

1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585
/**
 * check_conflicting_open - see if the given dentry points to a file that has
 * 			    an existing open that would conflict with the
 * 			    desired lease.
 * @dentry:	dentry to check
 * @arg:	type of lease that we're trying to acquire
 *
 * Check to see if there's an existing open fd on this file that would
 * conflict with the lease we're trying to set.
 */
static int
C
Christoph Hellwig 已提交
1586
check_conflicting_open(const struct dentry *dentry, const long arg, int flags)
1587 1588 1589 1590
{
	int ret = 0;
	struct inode *inode = dentry->d_inode;

C
Christoph Hellwig 已提交
1591 1592 1593
	if (flags & FL_LAYOUT)
		return 0;

1594 1595 1596 1597 1598 1599 1600 1601 1602 1603
	if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
		return -EAGAIN;

	if ((arg == F_WRLCK) && ((d_count(dentry) > 1) ||
	    (atomic_read(&inode->i_count) > 1)))
		ret = -EAGAIN;

	return ret;
}

1604 1605
static int
generic_add_lease(struct file *filp, long arg, struct file_lock **flp, void **priv)
L
Linus Torvalds 已提交
1606
{
1607
	struct file_lock *fl, *my_fl = NULL, *lease;
1608
	struct dentry *dentry = filp->f_path.dentry;
L
Linus Torvalds 已提交
1609
	struct inode *inode = dentry->d_inode;
1610
	struct file_lock_context *ctx;
J
J. Bruce Fields 已提交
1611
	bool is_deleg = (*flp)->fl_flags & FL_DELEG;
J
J. Bruce Fields 已提交
1612
	int error;
1613
	LIST_HEAD(dispose);
L
Linus Torvalds 已提交
1614

1615
	lease = *flp;
1616 1617
	trace_generic_add_lease(inode, lease);

1618 1619 1620 1621
	ctx = locks_get_lock_context(inode);
	if (!ctx)
		return -ENOMEM;

J
J. Bruce Fields 已提交
1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634
	/*
	 * In the delegation case we need mutual exclusion with
	 * a number of operations that take the i_mutex.  We trylock
	 * because delegations are an optional optimization, and if
	 * there's some chance of a conflict--we'd rather not
	 * bother, maybe that's a sign this just isn't a good file to
	 * hand out a delegation on.
	 */
	if (is_deleg && !mutex_trylock(&inode->i_mutex))
		return -EAGAIN;

	if (is_deleg && arg == F_WRLCK) {
		/* Write delegations are not currently supported: */
1635
		mutex_unlock(&inode->i_mutex);
J
J. Bruce Fields 已提交
1636 1637 1638
		WARN_ON_ONCE(1);
		return -EINVAL;
	}
1639

1640
	spin_lock(&ctx->flc_lock);
1641
	time_out_leases(inode, &dispose);
C
Christoph Hellwig 已提交
1642
	error = check_conflicting_open(dentry, arg, lease->fl_flags);
1643
	if (error)
1644
		goto out;
1645

L
Linus Torvalds 已提交
1646 1647 1648 1649 1650 1651 1652 1653
	/*
	 * At this point, we know that if there is an exclusive
	 * lease on this file, then we hold it on this filp
	 * (otherwise our open of this file would have blocked).
	 * And if we are trying to acquire an exclusive lease,
	 * then the file is not open by anyone (including us)
	 * except for this filp.
	 */
J
J. Bruce Fields 已提交
1654
	error = -EAGAIN;
1655
	list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1656 1657
		if (fl->fl_file == filp &&
		    fl->fl_owner == lease->fl_owner) {
1658
			my_fl = fl;
J
J. Bruce Fields 已提交
1659 1660
			continue;
		}
1661

J
J. Bruce Fields 已提交
1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673
		/*
		 * No exclusive leases if someone else has a lease on
		 * this file:
		 */
		if (arg == F_WRLCK)
			goto out;
		/*
		 * Modifying our existing lease is OK, but no getting a
		 * new lease if someone else is opening for write:
		 */
		if (fl->fl_flags & FL_UNLOCK_PENDING)
			goto out;
L
Linus Torvalds 已提交
1674 1675
	}

1676
	if (my_fl != NULL) {
1677
		error = lease->fl_lmops->lm_change(my_fl, arg, &dispose);
1678 1679 1680
		if (error)
			goto out;
		goto out_setup;
L
Linus Torvalds 已提交
1681 1682 1683 1684 1685 1686
	}

	error = -EINVAL;
	if (!leases_enable)
		goto out;

1687
	locks_insert_lock_ctx(lease, &ctx->flc_lease);
1688 1689 1690 1691 1692 1693 1694 1695 1696 1697
	/*
	 * The check in break_lease() is lockless. It's possible for another
	 * open to race in after we did the earlier check for a conflicting
	 * open but before the lease was inserted. Check again for a
	 * conflicting open and cancel the lease if there is one.
	 *
	 * We also add a barrier here to ensure that the insertion of the lock
	 * precedes these checks.
	 */
	smp_mb();
C
Christoph Hellwig 已提交
1698
	error = check_conflicting_open(dentry, arg, lease->fl_flags);
1699
	if (error) {
1700
		locks_unlink_lock_ctx(lease);
1701 1702
		goto out;
	}
1703 1704 1705 1706

out_setup:
	if (lease->fl_lmops->lm_setup)
		lease->fl_lmops->lm_setup(lease, priv);
L
Linus Torvalds 已提交
1707
out:
1708
	spin_unlock(&ctx->flc_lock);
1709
	locks_dispose_list(&dispose);
J
J. Bruce Fields 已提交
1710 1711
	if (is_deleg)
		mutex_unlock(&inode->i_mutex);
1712
	if (!error && !my_fl)
1713
		*flp = NULL;
L
Linus Torvalds 已提交
1714 1715
	return error;
}
1716

1717
static int generic_delete_lease(struct file *filp, void *owner)
1718
{
1719
	int error = -EAGAIN;
1720
	struct file_lock *fl, *victim = NULL;
1721 1722
	struct dentry *dentry = filp->f_path.dentry;
	struct inode *inode = dentry->d_inode;
1723
	struct file_lock_context *ctx = inode->i_flctx;
1724
	LIST_HEAD(dispose);
1725

1726 1727 1728 1729 1730
	if (!ctx) {
		trace_generic_delete_lease(inode, NULL);
		return error;
	}

1731
	spin_lock(&ctx->flc_lock);
1732
	list_for_each_entry(fl, &ctx->flc_lease, fl_list) {
1733 1734
		if (fl->fl_file == filp &&
		    fl->fl_owner == owner) {
1735
			victim = fl;
1736
			break;
1737
		}
1738
	}
1739
	trace_generic_delete_lease(inode, fl);
1740
	if (victim)
1741
		error = fl->fl_lmops->lm_change(victim, F_UNLCK, &dispose);
1742
	spin_unlock(&ctx->flc_lock);
1743
	locks_dispose_list(&dispose);
1744
	return error;
1745 1746 1747 1748
}

/**
 *	generic_setlease	-	sets a lease on an open file
1749 1750 1751 1752 1753
 *	@filp:	file pointer
 *	@arg:	type of lease to obtain
 *	@flp:	input - file_lock to use, output - file_lock inserted
 *	@priv:	private data for lm_setup (may be NULL if lm_setup
 *		doesn't require it)
1754 1755 1756 1757
 *
 *	The (input) flp->fl_lmops->lm_break function is required
 *	by break_lease().
 */
1758 1759
int generic_setlease(struct file *filp, long arg, struct file_lock **flp,
			void **priv)
1760 1761 1762 1763 1764
{
	struct dentry *dentry = filp->f_path.dentry;
	struct inode *inode = dentry->d_inode;
	int error;

1765
	if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE))
1766 1767 1768 1769 1770 1771 1772 1773 1774
		return -EACCES;
	if (!S_ISREG(inode->i_mode))
		return -EINVAL;
	error = security_file_lock(filp, arg);
	if (error)
		return error;

	switch (arg) {
	case F_UNLCK:
1775
		return generic_delete_lease(filp, *priv);
1776 1777
	case F_RDLCK:
	case F_WRLCK:
1778 1779 1780 1781
		if (!(*flp)->fl_lmops->lm_break) {
			WARN_ON_ONCE(1);
			return -ENOLCK;
		}
C
Christoph Hellwig 已提交
1782

1783
		return generic_add_lease(filp, arg, flp, priv);
1784
	default:
1785
		return -EINVAL;
1786 1787
	}
}
1788
EXPORT_SYMBOL(generic_setlease);
L
Linus Torvalds 已提交
1789

1790
/**
1791
 * vfs_setlease        -       sets a lease on an open file
1792 1793 1794 1795 1796
 * @filp:	file pointer
 * @arg:	type of lease to obtain
 * @lease:	file_lock to use when adding a lease
 * @priv:	private info for lm_setup when adding a lease (may be
 * 		NULL if lm_setup doesn't require it)
1797 1798 1799 1800 1801 1802
 *
 * Call this to establish a lease on the file. The "lease" argument is not
 * used for F_UNLCK requests and may be NULL. For commands that set or alter
 * an existing lease, the (*lease)->fl_lmops->lm_break operation must be set;
 * if not, this function will return -ENOLCK (and generate a scary-looking
 * stack trace).
1803 1804 1805
 *
 * The "priv" pointer is passed directly to the lm_setup function as-is. It
 * may be NULL if the lm_setup operation doesn't require it.
L
Linus Torvalds 已提交
1806
 */
1807 1808
int
vfs_setlease(struct file *filp, long arg, struct file_lock **lease, void **priv)
L
Linus Torvalds 已提交
1809
{
1810
	if (filp->f_op->setlease)
1811
		return filp->f_op->setlease(filp, arg, lease, priv);
1812
	else
1813
		return generic_setlease(filp, arg, lease, priv);
L
Linus Torvalds 已提交
1814
}
1815
EXPORT_SYMBOL_GPL(vfs_setlease);
L
Linus Torvalds 已提交
1816

1817
static int do_fcntl_add_lease(unsigned int fd, struct file *filp, long arg)
L
Linus Torvalds 已提交
1818
{
1819
	struct file_lock *fl;
1820
	struct fasync_struct *new;
L
Linus Torvalds 已提交
1821 1822
	int error;

1823 1824 1825
	fl = lease_alloc(filp, arg);
	if (IS_ERR(fl))
		return PTR_ERR(fl);
L
Linus Torvalds 已提交
1826

1827 1828 1829 1830 1831
	new = fasync_alloc();
	if (!new) {
		locks_free_lock(fl);
		return -ENOMEM;
	}
1832
	new->fa_fd = fd;
1833

1834
	error = vfs_setlease(filp, arg, &fl, (void **)&new);
1835 1836
	if (fl)
		locks_free_lock(fl);
1837 1838
	if (new)
		fasync_free(new);
L
Linus Torvalds 已提交
1839 1840 1841
	return error;
}

1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854
/**
 *	fcntl_setlease	-	sets a lease on an open file
 *	@fd: open file descriptor
 *	@filp: file pointer
 *	@arg: type of lease to obtain
 *
 *	Call this fcntl to establish a lease on the file.
 *	Note that you also need to call %F_SETSIG to
 *	receive a signal when the lease is broken.
 */
int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
{
	if (arg == F_UNLCK)
1855
		return vfs_setlease(filp, F_UNLCK, NULL, (void **)&filp);
1856 1857 1858
	return do_fcntl_add_lease(fd, filp, arg);
}

L
Linus Torvalds 已提交
1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871
/**
 * flock_lock_file_wait - Apply a FLOCK-style lock to a file
 * @filp: The file to apply the lock to
 * @fl: The lock to be applied
 *
 * Add a FLOCK style lock to a file.
 */
int flock_lock_file_wait(struct file *filp, struct file_lock *fl)
{
	int error;
	might_sleep();
	for (;;) {
		error = flock_lock_file(filp, fl);
1872
		if (error != FILE_LOCK_DEFERRED)
L
Linus Torvalds 已提交
1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 1890 1891 1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904
			break;
		error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
		if (!error)
			continue;

		locks_delete_block(fl);
		break;
	}
	return error;
}

EXPORT_SYMBOL(flock_lock_file_wait);

/**
 *	sys_flock: - flock() system call.
 *	@fd: the file descriptor to lock.
 *	@cmd: the type of lock to apply.
 *
 *	Apply a %FL_FLOCK style lock to an open file descriptor.
 *	The @cmd can be one of
 *
 *	%LOCK_SH -- a shared lock.
 *
 *	%LOCK_EX -- an exclusive lock.
 *
 *	%LOCK_UN -- remove an existing lock.
 *
 *	%LOCK_MAND -- a `mandatory' flock.  This exists to emulate Windows Share Modes.
 *
 *	%LOCK_MAND can be combined with %LOCK_READ or %LOCK_WRITE to allow other
 *	processes read and write access respectively.
 */
1905
SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
L
Linus Torvalds 已提交
1906
{
1907
	struct fd f = fdget(fd);
L
Linus Torvalds 已提交
1908 1909 1910 1911 1912
	struct file_lock *lock;
	int can_sleep, unlock;
	int error;

	error = -EBADF;
1913
	if (!f.file)
L
Linus Torvalds 已提交
1914 1915 1916 1917 1918 1919
		goto out;

	can_sleep = !(cmd & LOCK_NB);
	cmd &= ~LOCK_NB;
	unlock = (cmd == LOCK_UN);

1920
	if (!unlock && !(cmd & LOCK_MAND) &&
1921
	    !(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
L
Linus Torvalds 已提交
1922 1923
		goto out_putf;

1924 1925 1926
	lock = flock_make_lock(f.file, cmd);
	if (IS_ERR(lock)) {
		error = PTR_ERR(lock);
L
Linus Torvalds 已提交
1927
		goto out_putf;
1928 1929
	}

L
Linus Torvalds 已提交
1930 1931 1932
	if (can_sleep)
		lock->fl_flags |= FL_SLEEP;

1933
	error = security_file_lock(f.file, lock->fl_type);
L
Linus Torvalds 已提交
1934 1935 1936
	if (error)
		goto out_free;

A
Al Viro 已提交
1937
	if (f.file->f_op->flock)
1938
		error = f.file->f_op->flock(f.file,
L
Linus Torvalds 已提交
1939 1940 1941
					  (can_sleep) ? F_SETLKW : F_SETLK,
					  lock);
	else
1942
		error = flock_lock_file_wait(f.file, lock);
L
Linus Torvalds 已提交
1943 1944

 out_free:
1945
	locks_free_lock(lock);
L
Linus Torvalds 已提交
1946 1947

 out_putf:
1948
	fdput(f);
L
Linus Torvalds 已提交
1949 1950 1951 1952
 out:
	return error;
}

1953 1954 1955
/**
 * vfs_test_lock - test file byte range lock
 * @filp: The file to test lock for
1956
 * @fl: The lock to test; also used to hold result
1957 1958 1959 1960 1961 1962
 *
 * Returns -ERRNO on failure.  Indicates presence of conflicting lock by
 * setting conf->fl_type to something other than F_UNLCK.
 */
int vfs_test_lock(struct file *filp, struct file_lock *fl)
{
A
Al Viro 已提交
1963
	if (filp->f_op->lock)
1964 1965 1966 1967 1968 1969
		return filp->f_op->lock(filp, F_GETLK, fl);
	posix_test_lock(filp, fl);
	return 0;
}
EXPORT_SYMBOL_GPL(vfs_test_lock);

1970 1971
static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
{
1972
	flock->l_pid = IS_OFDLCK(fl) ? -1 : fl->fl_pid;
1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986
#if BITS_PER_LONG == 32
	/*
	 * Make sure we can represent the posix lock via
	 * legacy 32bit flock.
	 */
	if (fl->fl_start > OFFT_OFFSET_MAX)
		return -EOVERFLOW;
	if (fl->fl_end != OFFSET_MAX && fl->fl_end > OFFT_OFFSET_MAX)
		return -EOVERFLOW;
#endif
	flock->l_start = fl->fl_start;
	flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
		fl->fl_end - fl->fl_start + 1;
	flock->l_whence = 0;
1987
	flock->l_type = fl->fl_type;
1988 1989 1990 1991 1992 1993
	return 0;
}

#if BITS_PER_LONG == 32
static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
{
1994
	flock->l_pid = IS_OFDLCK(fl) ? -1 : fl->fl_pid;
1995 1996 1997 1998 1999 2000 2001 2002
	flock->l_start = fl->fl_start;
	flock->l_len = fl->fl_end == OFFSET_MAX ? 0 :
		fl->fl_end - fl->fl_start + 1;
	flock->l_whence = 0;
	flock->l_type = fl->fl_type;
}
#endif

L
Linus Torvalds 已提交
2003 2004 2005
/* Report the first existing lock that would conflict with l.
 * This implements the F_GETLK command of fcntl().
 */
2006
int fcntl_getlk(struct file *filp, unsigned int cmd, struct flock __user *l)
L
Linus Torvalds 已提交
2007
{
2008
	struct file_lock file_lock;
L
Linus Torvalds 已提交
2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022
	struct flock flock;
	int error;

	error = -EFAULT;
	if (copy_from_user(&flock, l, sizeof(flock)))
		goto out;
	error = -EINVAL;
	if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
		goto out;

	error = flock_to_posix_lock(filp, &file_lock, &flock);
	if (error)
		goto out;

2023
	if (cmd == F_OFD_GETLK) {
2024 2025 2026 2027
		error = -EINVAL;
		if (flock.l_pid != 0)
			goto out;

2028
		cmd = F_GETLK;
2029
		file_lock.fl_flags |= FL_OFDLCK;
2030
		file_lock.fl_owner = filp;
2031 2032
	}

2033 2034 2035
	error = vfs_test_lock(filp, &file_lock);
	if (error)
		goto out;
L
Linus Torvalds 已提交
2036
 
2037 2038 2039
	flock.l_type = file_lock.fl_type;
	if (file_lock.fl_type != F_UNLCK) {
		error = posix_lock_to_flock(&flock, &file_lock);
2040
		if (error)
2041
			goto rel_priv;
L
Linus Torvalds 已提交
2042 2043 2044 2045
	}
	error = -EFAULT;
	if (!copy_to_user(l, &flock, sizeof(flock)))
		error = 0;
2046 2047
rel_priv:
	locks_release_private(&file_lock);
L
Linus Torvalds 已提交
2048 2049 2050 2051
out:
	return error;
}

2052 2053 2054 2055 2056
/**
 * vfs_lock_file - file byte range lock
 * @filp: The file to apply the lock to
 * @cmd: type of locking operation (F_SETLK, F_GETLK, etc.)
 * @fl: The lock to be applied
2057 2058 2059 2060 2061 2062 2063 2064
 * @conf: Place to return a copy of the conflicting lock, if found.
 *
 * A caller that doesn't care about the conflicting lock may pass NULL
 * as the final argument.
 *
 * If the filesystem defines a private ->lock() method, then @conf will
 * be left unchanged; so a caller that cares should initialize it to
 * some acceptable default.
2065 2066 2067 2068
 *
 * To avoid blocking kernel daemons, such as lockd, that need to acquire POSIX
 * locks, the ->lock() interface may return asynchronously, before the lock has
 * been granted or denied by the underlying filesystem, if (and only if)
J
J. Bruce Fields 已提交
2069
 * lm_grant is set. Callers expecting ->lock() to return asynchronously
2070 2071
 * will only use F_SETLK, not F_SETLKW; they will set FL_SLEEP if (and only if)
 * the request is for a blocking lock. When ->lock() does return asynchronously,
J
J. Bruce Fields 已提交
2072
 * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
2073 2074
 * request completes.
 * If the request is for non-blocking lock the file system should return
2075 2076
 * FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
 * with the result. If the request timed out the callback routine will return a
2077 2078 2079 2080 2081
 * nonzero return code and the file system should release the lock. The file
 * system is also responsible to keep a corresponding posix lock when it
 * grants a lock so the VFS can find out which locks are locally held and do
 * the correct lock cleanup when required.
 * The underlying filesystem must not drop the kernel lock or call
J
J. Bruce Fields 已提交
2082
 * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
2083
 * return code.
2084
 */
2085
int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
2086
{
A
Al Viro 已提交
2087
	if (filp->f_op->lock)
2088 2089
		return filp->f_op->lock(filp, cmd, fl);
	else
2090
		return posix_lock_file(filp, fl, conf);
2091 2092 2093
}
EXPORT_SYMBOL_GPL(vfs_lock_file);

M
Miklos Szeredi 已提交
2094 2095 2096 2097 2098 2099 2100 2101 2102
static int do_lock_file_wait(struct file *filp, unsigned int cmd,
			     struct file_lock *fl)
{
	int error;

	error = security_file_lock(filp, fl->fl_type);
	if (error)
		return error;

2103 2104 2105
	for (;;) {
		error = vfs_lock_file(filp, cmd, fl, NULL);
		if (error != FILE_LOCK_DEFERRED)
M
Miklos Szeredi 已提交
2106
			break;
2107 2108 2109 2110 2111 2112
		error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
		if (!error)
			continue;

		locks_delete_block(fl);
		break;
M
Miklos Szeredi 已提交
2113 2114 2115 2116 2117
	}

	return error;
}

2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133
/* Ensure that fl->fl_filp has compatible f_mode for F_SETLK calls */
static int
check_fmode_for_setlk(struct file_lock *fl)
{
	switch (fl->fl_type) {
	case F_RDLCK:
		if (!(fl->fl_file->f_mode & FMODE_READ))
			return -EBADF;
		break;
	case F_WRLCK:
		if (!(fl->fl_file->f_mode & FMODE_WRITE))
			return -EBADF;
	}
	return 0;
}

L
Linus Torvalds 已提交
2134 2135 2136
/* Apply the lock described by l to an open file descriptor.
 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
 */
2137 2138
int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
		struct flock __user *l)
L
Linus Torvalds 已提交
2139 2140 2141 2142
{
	struct file_lock *file_lock = locks_alloc_lock();
	struct flock flock;
	struct inode *inode;
2143
	struct file *f;
L
Linus Torvalds 已提交
2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155
	int error;

	if (file_lock == NULL)
		return -ENOLCK;

	/*
	 * This might block, so we do it before checking the inode.
	 */
	error = -EFAULT;
	if (copy_from_user(&flock, l, sizeof(flock)))
		goto out;

A
Al Viro 已提交
2156
	inode = file_inode(filp);
L
Linus Torvalds 已提交
2157 2158 2159 2160

	/* Don't allow mandatory locks on files that may be memory mapped
	 * and shared.
	 */
2161
	if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
L
Linus Torvalds 已提交
2162 2163 2164 2165
		error = -EAGAIN;
		goto out;
	}

2166
again:
L
Linus Torvalds 已提交
2167 2168 2169
	error = flock_to_posix_lock(filp, file_lock, &flock);
	if (error)
		goto out;
2170

2171 2172 2173 2174
	error = check_fmode_for_setlk(file_lock);
	if (error)
		goto out;

2175 2176
	/*
	 * If the cmd is requesting file-private locks, then set the
2177
	 * FL_OFDLCK flag and override the owner.
2178 2179
	 */
	switch (cmd) {
2180
	case F_OFD_SETLK:
2181 2182 2183 2184
		error = -EINVAL;
		if (flock.l_pid != 0)
			goto out;

2185
		cmd = F_SETLK;
2186
		file_lock->fl_flags |= FL_OFDLCK;
2187
		file_lock->fl_owner = filp;
2188
		break;
2189
	case F_OFD_SETLKW:
2190 2191 2192 2193
		error = -EINVAL;
		if (flock.l_pid != 0)
			goto out;

2194
		cmd = F_SETLKW;
2195
		file_lock->fl_flags |= FL_OFDLCK;
2196
		file_lock->fl_owner = filp;
2197 2198
		/* Fallthrough */
	case F_SETLKW:
L
Linus Torvalds 已提交
2199 2200
		file_lock->fl_flags |= FL_SLEEP;
	}
2201

M
Miklos Szeredi 已提交
2202
	error = do_lock_file_wait(filp, cmd, file_lock);
L
Linus Torvalds 已提交
2203

2204 2205 2206 2207
	/*
	 * Attempt to detect a close/fcntl race and recover by
	 * releasing the lock that was just acquired.
	 */
2208 2209
	/*
	 * we need that spin_lock here - it prevents reordering between
2210
	 * update of i_flctx->flc_posix and check for it done in close().
2211 2212 2213 2214 2215 2216
	 * rcu_read_lock() wouldn't do.
	 */
	spin_lock(&current->files->file_lock);
	f = fcheck(fd);
	spin_unlock(&current->files->file_lock);
	if (!error && f != filp && flock.l_type != F_UNLCK) {
2217 2218
		flock.l_type = F_UNLCK;
		goto again;
L
Linus Torvalds 已提交
2219 2220
	}

2221
out:
L
Linus Torvalds 已提交
2222 2223 2224 2225 2226 2227 2228 2229
	locks_free_lock(file_lock);
	return error;
}

#if BITS_PER_LONG == 32
/* Report the first existing lock that would conflict with l.
 * This implements the F_GETLK command of fcntl().
 */
2230
int fcntl_getlk64(struct file *filp, unsigned int cmd, struct flock64 __user *l)
L
Linus Torvalds 已提交
2231
{
2232
	struct file_lock file_lock;
L
Linus Torvalds 已提交
2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246
	struct flock64 flock;
	int error;

	error = -EFAULT;
	if (copy_from_user(&flock, l, sizeof(flock)))
		goto out;
	error = -EINVAL;
	if ((flock.l_type != F_RDLCK) && (flock.l_type != F_WRLCK))
		goto out;

	error = flock64_to_posix_lock(filp, &file_lock, &flock);
	if (error)
		goto out;

2247
	if (cmd == F_OFD_GETLK) {
2248 2249 2250 2251
		error = -EINVAL;
		if (flock.l_pid != 0)
			goto out;

2252
		cmd = F_GETLK64;
2253
		file_lock.fl_flags |= FL_OFDLCK;
2254
		file_lock.fl_owner = filp;
2255 2256
	}

2257 2258 2259 2260
	error = vfs_test_lock(filp, &file_lock);
	if (error)
		goto out;

2261 2262 2263 2264
	flock.l_type = file_lock.fl_type;
	if (file_lock.fl_type != F_UNLCK)
		posix_lock_to_flock64(&flock, &file_lock);

L
Linus Torvalds 已提交
2265 2266 2267
	error = -EFAULT;
	if (!copy_to_user(l, &flock, sizeof(flock)))
		error = 0;
2268 2269

	locks_release_private(&file_lock);
L
Linus Torvalds 已提交
2270 2271 2272 2273 2274 2275 2276
out:
	return error;
}

/* Apply the lock described by l to an open file descriptor.
 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
 */
2277 2278
int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
		struct flock64 __user *l)
L
Linus Torvalds 已提交
2279 2280 2281 2282
{
	struct file_lock *file_lock = locks_alloc_lock();
	struct flock64 flock;
	struct inode *inode;
2283
	struct file *f;
L
Linus Torvalds 已提交
2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295
	int error;

	if (file_lock == NULL)
		return -ENOLCK;

	/*
	 * This might block, so we do it before checking the inode.
	 */
	error = -EFAULT;
	if (copy_from_user(&flock, l, sizeof(flock)))
		goto out;

A
Al Viro 已提交
2296
	inode = file_inode(filp);
L
Linus Torvalds 已提交
2297 2298 2299 2300

	/* Don't allow mandatory locks on files that may be memory mapped
	 * and shared.
	 */
2301
	if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
L
Linus Torvalds 已提交
2302 2303 2304 2305
		error = -EAGAIN;
		goto out;
	}

2306
again:
L
Linus Torvalds 已提交
2307 2308 2309
	error = flock64_to_posix_lock(filp, file_lock, &flock);
	if (error)
		goto out;
2310

2311 2312 2313 2314
	error = check_fmode_for_setlk(file_lock);
	if (error)
		goto out;

2315 2316
	/*
	 * If the cmd is requesting file-private locks, then set the
2317
	 * FL_OFDLCK flag and override the owner.
2318 2319
	 */
	switch (cmd) {
2320
	case F_OFD_SETLK:
2321 2322 2323 2324
		error = -EINVAL;
		if (flock.l_pid != 0)
			goto out;

2325
		cmd = F_SETLK64;
2326
		file_lock->fl_flags |= FL_OFDLCK;
2327
		file_lock->fl_owner = filp;
2328
		break;
2329
	case F_OFD_SETLKW:
2330 2331 2332 2333
		error = -EINVAL;
		if (flock.l_pid != 0)
			goto out;

2334
		cmd = F_SETLKW64;
2335
		file_lock->fl_flags |= FL_OFDLCK;
2336
		file_lock->fl_owner = filp;
2337 2338
		/* Fallthrough */
	case F_SETLKW64:
L
Linus Torvalds 已提交
2339 2340
		file_lock->fl_flags |= FL_SLEEP;
	}
2341

M
Miklos Szeredi 已提交
2342
	error = do_lock_file_wait(filp, cmd, file_lock);
L
Linus Torvalds 已提交
2343

2344 2345 2346 2347
	/*
	 * Attempt to detect a close/fcntl race and recover by
	 * releasing the lock that was just acquired.
	 */
2348 2349 2350 2351
	spin_lock(&current->files->file_lock);
	f = fcheck(fd);
	spin_unlock(&current->files->file_lock);
	if (!error && f != filp && flock.l_type != F_UNLCK) {
2352 2353
		flock.l_type = F_UNLCK;
		goto again;
L
Linus Torvalds 已提交
2354 2355 2356 2357 2358 2359 2360 2361 2362 2363 2364 2365 2366 2367 2368
	}

out:
	locks_free_lock(file_lock);
	return error;
}
#endif /* BITS_PER_LONG == 32 */

/*
 * This function is called when the file is being removed
 * from the task's fd array.  POSIX locks belonging to this task
 * are deleted at this time.
 */
void locks_remove_posix(struct file *filp, fl_owner_t owner)
{
2369
	struct file_lock lock;
2370
	struct file_lock_context *ctx = file_inode(filp)->i_flctx;
L
Linus Torvalds 已提交
2371 2372 2373 2374 2375 2376

	/*
	 * If there are no locks held on this file, we don't need to call
	 * posix_lock_file().  Another process could be setting a lock on this
	 * file at the same time, but we wouldn't remove that lock anyway.
	 */
2377
	if (!ctx || list_empty(&ctx->flc_posix))
L
Linus Torvalds 已提交
2378 2379 2380
		return;

	lock.fl_type = F_UNLCK;
2381
	lock.fl_flags = FL_POSIX | FL_CLOSE;
L
Linus Torvalds 已提交
2382 2383 2384 2385 2386 2387 2388 2389
	lock.fl_start = 0;
	lock.fl_end = OFFSET_MAX;
	lock.fl_owner = owner;
	lock.fl_pid = current->tgid;
	lock.fl_file = filp;
	lock.fl_ops = NULL;
	lock.fl_lmops = NULL;

2390
	vfs_lock_file(filp, F_SETLK, &lock, NULL);
L
Linus Torvalds 已提交
2391 2392 2393 2394 2395 2396 2397

	if (lock.fl_ops && lock.fl_ops->fl_release_private)
		lock.fl_ops->fl_release_private(&lock);
}

EXPORT_SYMBOL(locks_remove_posix);

2398
/* The i_flctx must be valid when calling into here */
2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409
static void
locks_remove_flock(struct file *filp)
{
	struct file_lock fl = {
		.fl_owner = filp,
		.fl_pid = current->tgid,
		.fl_file = filp,
		.fl_flags = FL_FLOCK,
		.fl_type = F_UNLCK,
		.fl_end = OFFSET_MAX,
	};
2410
	struct file_lock_context *flctx = file_inode(filp)->i_flctx;
2411

2412
	if (list_empty(&flctx->flc_flock))
2413 2414 2415 2416 2417 2418 2419 2420 2421 2422 2423
		return;

	if (filp->f_op->flock)
		filp->f_op->flock(filp, F_SETLKW, &fl);
	else
		flock_lock_file(filp, &fl);

	if (fl.fl_ops && fl.fl_ops->fl_release_private)
		fl.fl_ops->fl_release_private(&fl);
}

2424
/* The i_flctx must be valid when calling into here */
2425 2426 2427 2428 2429 2430 2431 2432
static void
locks_remove_lease(struct file *filp)
{
	struct inode *inode = file_inode(filp);
	struct file_lock_context *ctx = inode->i_flctx;
	struct file_lock *fl, *tmp;
	LIST_HEAD(dispose);

2433
	if (list_empty(&ctx->flc_lease))
2434 2435
		return;

2436
	spin_lock(&ctx->flc_lock);
2437
	list_for_each_entry_safe(fl, tmp, &ctx->flc_lease, fl_list)
2438
		lease_modify(fl, F_UNLCK, &dispose);
2439
	spin_unlock(&ctx->flc_lock);
2440 2441 2442
	locks_dispose_list(&dispose);
}

L
Linus Torvalds 已提交
2443 2444 2445
/*
 * This function is called on the last close of an open file.
 */
2446
void locks_remove_file(struct file *filp)
L
Linus Torvalds 已提交
2447
{
2448 2449 2450
	if (!file_inode(filp)->i_flctx)
		return;

2451
	/* remove any OFD locks */
2452
	locks_remove_posix(filp, filp);
2453

2454 2455 2456
	/* remove flock locks */
	locks_remove_flock(filp);

2457 2458
	/* remove any leases */
	locks_remove_lease(filp);
L
Linus Torvalds 已提交
2459 2460 2461 2462 2463 2464 2465 2466
}

/**
 *	posix_unblock_lock - stop waiting for a file lock
 *	@waiter: the lock which was waiting
 *
 *	lockd needs to block waiting for locks.
 */
J
J. Bruce Fields 已提交
2467
int
2468
posix_unblock_lock(struct file_lock *waiter)
L
Linus Torvalds 已提交
2469
{
J
J. Bruce Fields 已提交
2470 2471
	int status = 0;

2472
	spin_lock(&blocked_lock_lock);
2473
	if (waiter->fl_next)
L
Linus Torvalds 已提交
2474
		__locks_delete_block(waiter);
J
J. Bruce Fields 已提交
2475 2476
	else
		status = -ENOENT;
2477
	spin_unlock(&blocked_lock_lock);
J
J. Bruce Fields 已提交
2478
	return status;
L
Linus Torvalds 已提交
2479 2480 2481
}
EXPORT_SYMBOL(posix_unblock_lock);

M
Marc Eshel 已提交
2482 2483 2484 2485 2486 2487 2488 2489 2490
/**
 * vfs_cancel_lock - file byte range unblock lock
 * @filp: The file to apply the unblock to
 * @fl: The lock to be unblocked
 *
 * Used by lock managers to cancel blocked requests
 */
int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
{
A
Al Viro 已提交
2491
	if (filp->f_op->lock)
M
Marc Eshel 已提交
2492 2493 2494 2495 2496 2497
		return filp->f_op->lock(filp, F_CANCELLK, fl);
	return 0;
}

EXPORT_SYMBOL_GPL(vfs_cancel_lock);

2498
#ifdef CONFIG_PROC_FS
2499
#include <linux/proc_fs.h>
2500 2501
#include <linux/seq_file.h>

2502 2503 2504 2505 2506
struct locks_iterator {
	int	li_cpu;
	loff_t	li_pos;
};

2507
static void lock_get_status(struct seq_file *f, struct file_lock *fl,
2508
			    loff_t id, char *pfx)
L
Linus Torvalds 已提交
2509 2510
{
	struct inode *inode = NULL;
2511 2512 2513
	unsigned int fl_pid;

	if (fl->fl_nspid)
2514
		fl_pid = pid_vnr(fl->fl_nspid);
2515 2516
	else
		fl_pid = fl->fl_pid;
L
Linus Torvalds 已提交
2517 2518

	if (fl->fl_file != NULL)
A
Al Viro 已提交
2519
		inode = file_inode(fl->fl_file);
L
Linus Torvalds 已提交
2520

2521
	seq_printf(f, "%lld:%s ", id, pfx);
L
Linus Torvalds 已提交
2522
	if (IS_POSIX(fl)) {
2523
		if (fl->fl_flags & FL_ACCESS)
2524
			seq_puts(f, "ACCESS");
2525
		else if (IS_OFDLCK(fl))
2526
			seq_puts(f, "OFDLCK");
2527
		else
2528
			seq_puts(f, "POSIX ");
2529 2530

		seq_printf(f, " %s ",
L
Linus Torvalds 已提交
2531
			     (inode == NULL) ? "*NOINODE*" :
2532
			     mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
L
Linus Torvalds 已提交
2533 2534
	} else if (IS_FLOCK(fl)) {
		if (fl->fl_type & LOCK_MAND) {
2535
			seq_puts(f, "FLOCK  MSNFS     ");
L
Linus Torvalds 已提交
2536
		} else {
2537
			seq_puts(f, "FLOCK  ADVISORY  ");
L
Linus Torvalds 已提交
2538 2539
		}
	} else if (IS_LEASE(fl)) {
2540 2541 2542 2543 2544
		if (fl->fl_flags & FL_DELEG)
			seq_puts(f, "DELEG  ");
		else
			seq_puts(f, "LEASE  ");

J
J. Bruce Fields 已提交
2545
		if (lease_breaking(fl))
2546
			seq_puts(f, "BREAKING  ");
L
Linus Torvalds 已提交
2547
		else if (fl->fl_file)
2548
			seq_puts(f, "ACTIVE    ");
L
Linus Torvalds 已提交
2549
		else
2550
			seq_puts(f, "BREAKER   ");
L
Linus Torvalds 已提交
2551
	} else {
2552
		seq_puts(f, "UNKNOWN UNKNOWN  ");
L
Linus Torvalds 已提交
2553 2554
	}
	if (fl->fl_type & LOCK_MAND) {
2555
		seq_printf(f, "%s ",
L
Linus Torvalds 已提交
2556 2557 2558 2559
			       (fl->fl_type & LOCK_READ)
			       ? (fl->fl_type & LOCK_WRITE) ? "RW   " : "READ "
			       : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
	} else {
2560
		seq_printf(f, "%s ",
J
J. Bruce Fields 已提交
2561
			       (lease_breaking(fl))
2562 2563
			       ? (fl->fl_type == F_UNLCK) ? "UNLCK" : "READ "
			       : (fl->fl_type == F_WRLCK) ? "WRITE" : "READ ");
L
Linus Torvalds 已提交
2564 2565 2566
	}
	if (inode) {
#ifdef WE_CAN_BREAK_LSLK_NOW
2567
		seq_printf(f, "%d %s:%ld ", fl_pid,
L
Linus Torvalds 已提交
2568 2569 2570
				inode->i_sb->s_id, inode->i_ino);
#else
		/* userspace relies on this representation of dev_t ;-( */
2571
		seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
L
Linus Torvalds 已提交
2572 2573 2574 2575
				MAJOR(inode->i_sb->s_dev),
				MINOR(inode->i_sb->s_dev), inode->i_ino);
#endif
	} else {
2576
		seq_printf(f, "%d <none>:0 ", fl_pid);
L
Linus Torvalds 已提交
2577 2578 2579
	}
	if (IS_POSIX(fl)) {
		if (fl->fl_end == OFFSET_MAX)
2580
			seq_printf(f, "%Ld EOF\n", fl->fl_start);
L
Linus Torvalds 已提交
2581
		else
2582
			seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
L
Linus Torvalds 已提交
2583
	} else {
2584
		seq_puts(f, "0 EOF\n");
L
Linus Torvalds 已提交
2585 2586 2587
	}
}

2588
static int locks_show(struct seq_file *f, void *v)
L
Linus Torvalds 已提交
2589
{
2590
	struct locks_iterator *iter = f->private;
2591
	struct file_lock *fl, *bfl;
L
Linus Torvalds 已提交
2592

2593
	fl = hlist_entry(v, struct file_lock, fl_link);
L
Linus Torvalds 已提交
2594

2595
	lock_get_status(f, fl, iter->li_pos, "");
L
Linus Torvalds 已提交
2596

2597
	list_for_each_entry(bfl, &fl->fl_block, fl_block)
2598
		lock_get_status(f, bfl, iter->li_pos, " ->");
2599

2600 2601
	return 0;
}
L
Linus Torvalds 已提交
2602

2603
static void *locks_start(struct seq_file *f, loff_t *pos)
2604
	__acquires(&blocked_lock_lock)
2605
{
2606
	struct locks_iterator *iter = f->private;
2607

2608 2609
	iter->li_pos = *pos + 1;
	lg_global_lock(&file_lock_lglock);
2610
	spin_lock(&blocked_lock_lock);
2611
	return seq_hlist_start_percpu(&file_lock_list, &iter->li_cpu, *pos);
2612
}
L
Linus Torvalds 已提交
2613

2614 2615
static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
{
2616 2617 2618 2619
	struct locks_iterator *iter = f->private;

	++iter->li_pos;
	return seq_hlist_next_percpu(v, &file_lock_list, &iter->li_cpu, pos);
2620
}
L
Linus Torvalds 已提交
2621

2622
static void locks_stop(struct seq_file *f, void *v)
2623
	__releases(&blocked_lock_lock)
2624
{
2625
	spin_unlock(&blocked_lock_lock);
2626
	lg_global_unlock(&file_lock_lglock);
L
Linus Torvalds 已提交
2627 2628
}

2629
static const struct seq_operations locks_seq_operations = {
2630 2631 2632 2633 2634
	.start	= locks_start,
	.next	= locks_next,
	.stop	= locks_stop,
	.show	= locks_show,
};
2635 2636 2637

static int locks_open(struct inode *inode, struct file *filp)
{
2638 2639
	return seq_open_private(filp, &locks_seq_operations,
					sizeof(struct locks_iterator));
2640 2641 2642 2643 2644 2645
}

static const struct file_operations proc_locks_operations = {
	.open		= locks_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
2646
	.release	= seq_release_private,
2647 2648 2649 2650 2651 2652 2653 2654
};

static int __init proc_locks_init(void)
{
	proc_create("locks", 0, NULL, &proc_locks_operations);
	return 0;
}
module_init(proc_locks_init);
2655 2656
#endif

L
Linus Torvalds 已提交
2657 2658
static int __init filelock_init(void)
{
2659 2660
	int i;

2661 2662 2663
	flctx_cache = kmem_cache_create("file_lock_ctx",
			sizeof(struct file_lock_context), 0, SLAB_PANIC, NULL);

L
Linus Torvalds 已提交
2664
	filelock_cache = kmem_cache_create("file_lock_cache",
M
Miklos Szeredi 已提交
2665 2666
			sizeof(struct file_lock), 0, SLAB_PANIC, NULL);

2667 2668 2669 2670 2671
	lg_lock_init(&file_lock_lglock, "file_lock_lglock");

	for_each_possible_cpu(i)
		INIT_HLIST_HEAD(per_cpu_ptr(&file_lock_list, i));

L
Linus Torvalds 已提交
2672 2673 2674 2675
	return 0;
}

core_initcall(filelock_init);