locks.c 57.6 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.
 *  See 'Documentation/mandatory.txt' for details.
 *  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/smp_lock.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 <asm/uaccess.h>

#define IS_POSIX(fl)	(fl->fl_flags & FL_POSIX)
#define IS_FLOCK(fl)	(fl->fl_flags & FL_FLOCK)
#define IS_LEASE(fl)	(fl->fl_flags & FL_LEASE)

int leases_enable = 1;
int lease_break_time = 45;

#define for_each_lock(inode, lockp) \
	for (lockp = &inode->i_flock; *lockp != NULL; lockp = &(*lockp)->fl_next)

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static LIST_HEAD(file_lock_list);
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static LIST_HEAD(blocked_list);

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static struct kmem_cache *filelock_cache __read_mostly;
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/* Allocate an empty lock structure. */
static struct file_lock *locks_alloc_lock(void)
{
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	return kmem_cache_alloc(filelock_cache, GFP_KERNEL);
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}

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static void locks_release_private(struct file_lock *fl)
{
	if (fl->fl_ops) {
		if (fl->fl_ops->fl_release_private)
			fl->fl_ops->fl_release_private(fl);
		fl->fl_ops = NULL;
	}
	if (fl->fl_lmops) {
		if (fl->fl_lmops->fl_release_private)
			fl->fl_lmops->fl_release_private(fl);
		fl->fl_lmops = NULL;
	}

}

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/* Free a lock which is not in use. */
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static void locks_free_lock(struct file_lock *fl)
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{
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	BUG_ON(waitqueue_active(&fl->fl_wait));
	BUG_ON(!list_empty(&fl->fl_block));
	BUG_ON(!list_empty(&fl->fl_link));
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	locks_release_private(fl);
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	kmem_cache_free(filelock_cache, fl);
}

void locks_init_lock(struct file_lock *fl)
{
	INIT_LIST_HEAD(&fl->fl_link);
	INIT_LIST_HEAD(&fl->fl_block);
	init_waitqueue_head(&fl->fl_wait);
	fl->fl_next = NULL;
	fl->fl_fasync = NULL;
	fl->fl_owner = NULL;
	fl->fl_pid = 0;
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	fl->fl_nspid = NULL;
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	fl->fl_file = NULL;
	fl->fl_flags = 0;
	fl->fl_type = 0;
	fl->fl_start = fl->fl_end = 0;
	fl->fl_ops = NULL;
	fl->fl_lmops = NULL;
}

EXPORT_SYMBOL(locks_init_lock);

/*
 * Initialises the fields of the file lock which are invariant for
 * free file_locks.
 */
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static void init_once(void *foo)
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{
	struct file_lock *lock = (struct file_lock *) foo;

	locks_init_lock(lock);
}

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static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
{
	if (fl->fl_ops) {
		if (fl->fl_ops->fl_copy_lock)
			fl->fl_ops->fl_copy_lock(new, fl);
		new->fl_ops = fl->fl_ops;
	}
	if (fl->fl_lmops) {
		if (fl->fl_lmops->fl_copy_lock)
			fl->fl_lmops->fl_copy_lock(new, fl);
		new->fl_lmops = fl->fl_lmops;
	}
}

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/*
 * Initialize a new lock from an existing file_lock structure.
 */
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void __locks_copy_lock(struct file_lock *new, const 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_ops = NULL;
	new->fl_lmops = NULL;
}
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EXPORT_SYMBOL(__locks_copy_lock);
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void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
{
	locks_release_private(new);

	__locks_copy_lock(new, fl);
	new->fl_file = fl->fl_file;
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	new->fl_ops = fl->fl_ops;
	new->fl_lmops = fl->fl_lmops;
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	locks_copy_private(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. */
static int flock_make_lock(struct file *filp, struct file_lock **lock,
		unsigned int cmd)
{
	struct file_lock *fl;
	int type = flock_translate_cmd(cmd);
	if (type < 0)
		return type;
	
	fl = locks_alloc_lock();
	if (fl == NULL)
		return -ENOMEM;

	fl->fl_file = filp;
	fl->fl_pid = current->tgid;
	fl->fl_flags = FL_FLOCK;
	fl->fl_type = type;
	fl->fl_end = OFFSET_MAX;
	
	*lock = fl;
	return 0;
}

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

/* 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)
{
	off_t start, end;

	switch (l->l_whence) {
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	case SEEK_SET:
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		start = 0;
		break;
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	case SEEK_CUR:
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		start = filp->f_pos;
		break;
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	case SEEK_END:
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		start = i_size_read(filp->f_path.dentry->d_inode);
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		break;
	default:
		return -EINVAL;
	}

	/* POSIX-1996 leaves the case l->l_len < 0 undefined;
	   POSIX-2001 defines it. */
	start += l->l_start;
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	if (start < 0)
		return -EINVAL;
	fl->fl_end = OFFSET_MAX;
	if (l->l_len > 0) {
		end = start + l->l_len - 1;
		fl->fl_end = end;
	} else if (l->l_len < 0) {
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		end = start - 1;
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		fl->fl_end = end;
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		start += l->l_len;
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		if (start < 0)
			return -EINVAL;
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	}
	fl->fl_start = start;	/* we record the absolute position */
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	if (fl->fl_end < fl->fl_start)
		return -EOVERFLOW;
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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);
}

#if BITS_PER_LONG == 32
static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
				 struct flock64 *l)
{
	loff_t start;

	switch (l->l_whence) {
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	case SEEK_SET:
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		start = 0;
		break;
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	case SEEK_CUR:
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		start = filp->f_pos;
		break;
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	case SEEK_END:
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		start = i_size_read(filp->f_path.dentry->d_inode);
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		break;
	default:
		return -EINVAL;
	}

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	start += l->l_start;
	if (start < 0)
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		return -EINVAL;
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	fl->fl_end = OFFSET_MAX;
	if (l->l_len > 0) {
		fl->fl_end = start + l->l_len - 1;
	} else if (l->l_len < 0) {
		fl->fl_end = start - 1;
		start += l->l_len;
		if (start < 0)
			return -EINVAL;
	}
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	fl->fl_start = start;	/* we record the absolute position */
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	if (fl->fl_end < fl->fl_start)
		return -EOVERFLOW;
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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;

	switch (l->l_type) {
	case F_RDLCK:
	case F_WRLCK:
	case F_UNLCK:
		fl->fl_type = l->l_type;
		break;
	default:
		return -EINVAL;
	}

	return (0);
}
#endif

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

static void lease_release_private_callback(struct file_lock *fl)
{
	if (!fl->fl_file)
		return;

	f_delown(fl->fl_file);
	fl->fl_file->f_owner.signum = 0;
}

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static int lease_mylease_callback(struct file_lock *fl, struct file_lock *try)
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{
	return fl->fl_file == try->fl_file;
}

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static struct lock_manager_operations lease_manager_ops = {
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	.fl_break = lease_break_callback,
	.fl_release_private = lease_release_private_callback,
	.fl_mylease = lease_mylease_callback,
	.fl_change = lease_modify,
};

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

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	fl->fl_owner = current->files;
	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, int 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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{
	if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner)
		return fl2->fl_lmops == fl1->fl_lmops &&
			fl1->fl_lmops->fl_compare_owner(fl1, fl2);
	return fl1->fl_owner == fl2->fl_owner;
}

/* Remove waiter from blocker's block list.
 * When blocker ends up pointing to itself then the list is empty.
 */
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static void __locks_delete_block(struct file_lock *waiter)
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{
	list_del_init(&waiter->fl_block);
	list_del_init(&waiter->fl_link);
	waiter->fl_next = NULL;
}

/*
 */
static void locks_delete_block(struct file_lock *waiter)
{
	lock_kernel();
	__locks_delete_block(waiter);
	unlock_kernel();
}

/* 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.
 */
static void locks_insert_block(struct file_lock *blocker, 
			       struct file_lock *waiter)
{
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	BUG_ON(!list_empty(&waiter->fl_block));
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	list_add_tail(&waiter->fl_block, &blocker->fl_block);
	waiter->fl_next = blocker;
	if (IS_POSIX(blocker))
		list_add(&waiter->fl_link, &blocked_list);
}

/* Wake up processes blocked waiting for blocker.
 * If told to wait then schedule the processes until the block list
 * is empty, otherwise empty the block list ourselves.
 */
static void locks_wake_up_blocks(struct file_lock *blocker)
{
	while (!list_empty(&blocker->fl_block)) {
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		struct file_lock *waiter;

		waiter = list_first_entry(&blocker->fl_block,
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				struct file_lock, fl_block);
		__locks_delete_block(waiter);
		if (waiter->fl_lmops && waiter->fl_lmops->fl_notify)
			waiter->fl_lmops->fl_notify(waiter);
		else
			wake_up(&waiter->fl_wait);
	}
}

/* Insert file lock fl into an inode's lock list at the position indicated
 * by pos. At the same time add the lock to the global file lock list.
 */
static void locks_insert_lock(struct file_lock **pos, struct file_lock *fl)
{
	list_add(&fl->fl_link, &file_lock_list);

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	fl->fl_nspid = get_pid(task_tgid(current));

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	/* insert into file's list */
	fl->fl_next = *pos;
	*pos = fl;
}

/*
 * Delete a lock and then free it.
 * Wake up processes that are blocked waiting for this lock,
 * notify the FS that the lock has been cleared and
 * finally free the lock.
 */
static void locks_delete_lock(struct file_lock **thisfl_p)
{
	struct file_lock *fl = *thisfl_p;

	*thisfl_p = fl->fl_next;
	fl->fl_next = NULL;
	list_del_init(&fl->fl_link);

	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;
	}

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	if (fl->fl_nspid) {
		put_pid(fl->fl_nspid);
		fl->fl_nspid = NULL;
	}

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	locks_wake_up_blocks(fl);
	locks_free_lock(fl);
}

/* 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));
}

641
void
642
posix_test_lock(struct file *filp, struct file_lock *fl)
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643 644 645 646
{
	struct file_lock *cfl;

	lock_kernel();
647
	for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
L
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		if (!IS_POSIX(cfl))
			continue;
650
		if (posix_locks_conflict(fl, cfl))
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			break;
	}
653
	if (cfl) {
654
		__locks_copy_lock(fl, cfl);
655
		if (cfl->fl_nspid)
656
			fl->fl_pid = pid_vnr(cfl->fl_nspid);
657
	} else
658
		fl->fl_type = F_UNLCK;
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	unlock_kernel();
660
	return;
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}
EXPORT_SYMBOL(posix_test_lock);

664 665 666 667 668
/*
 * Deadlock detection:
 *
 * We attempt to detect deadlocks that are due purely to posix file
 * locks.
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 *
670 671 672 673 674 675 676
 * 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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 *
678 679 680
 * 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.
681
 *
682 683 684 685 686
 * 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.
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 */
688 689 690

#define MAX_DEADLK_ITERATIONS 10

691 692 693 694 695 696 697 698 699 700 701 702
/* 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;

	list_for_each_entry(fl, &blocked_list, fl_link) {
		if (posix_same_owner(fl, block_fl))
			return fl->fl_next;
	}
	return NULL;
}

703
static int posix_locks_deadlock(struct file_lock *caller_fl,
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				struct file_lock *block_fl)
{
706
	int i = 0;
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708 709 710 711 712
	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;
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	}
	return 0;
}

/* Try to create a FLOCK lock on filp. We always insert new FLOCK locks
718
 * after any leases, but before any posix locks.
719 720 721 722
 *
 * 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.
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 */
724
static int flock_lock_file(struct file *filp, struct file_lock *request)
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{
726
	struct file_lock *new_fl = NULL;
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	struct file_lock **before;
728
	struct inode * inode = filp->f_path.dentry->d_inode;
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	int error = 0;
	int found = 0;

	lock_kernel();
733 734
	if (request->fl_flags & FL_ACCESS)
		goto find_conflict;
735 736 737 738 739 740 741 742 743

	if (request->fl_type != F_UNLCK) {
		error = -ENOMEM;
		new_fl = locks_alloc_lock();
		if (new_fl == NULL)
			goto out;
		error = 0;
	}

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	for_each_lock(inode, before) {
		struct file_lock *fl = *before;
		if (IS_POSIX(fl))
			break;
		if (IS_LEASE(fl))
			continue;
		if (filp != fl->fl_file)
			continue;
752
		if (request->fl_type == fl->fl_type)
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			goto out;
		found = 1;
		locks_delete_lock(before);
		break;
	}

759 760 761
	if (request->fl_type == F_UNLCK) {
		if ((request->fl_flags & FL_EXISTS) && !found)
			error = -ENOENT;
762
		goto out;
763
	}
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	/*
	 * If a higher-priority process was blocked on the old file lock,
	 * give it the opportunity to lock the file.
	 */
	if (found)
770
		cond_resched_bkl();
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771

772
find_conflict:
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	for_each_lock(inode, before) {
		struct file_lock *fl = *before;
		if (IS_POSIX(fl))
			break;
		if (IS_LEASE(fl))
			continue;
779
		if (!flock_locks_conflict(request, fl))
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			continue;
		error = -EAGAIN;
782 783 784 785
		if (!(request->fl_flags & FL_SLEEP))
			goto out;
		error = FILE_LOCK_DEFERRED;
		locks_insert_block(fl, request);
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		goto out;
	}
788 789
	if (request->fl_flags & FL_ACCESS)
		goto out;
790
	locks_copy_lock(new_fl, request);
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Pavel Emelyanov 已提交
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	locks_insert_lock(before, new_fl);
792
	new_fl = NULL;
793
	error = 0;
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out:
	unlock_kernel();
797 798
	if (new_fl)
		locks_free_lock(new_fl);
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	return error;
}

802
static int __posix_lock_file(struct inode *inode, struct file_lock *request, struct file_lock *conflock)
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{
	struct file_lock *fl;
805 806
	struct file_lock *new_fl = NULL;
	struct file_lock *new_fl2 = NULL;
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	struct file_lock *left = NULL;
	struct file_lock *right = NULL;
	struct file_lock **before;
	int error, added = 0;

	/*
	 * We may need two file_lock structures for this operation,
	 * so we get them in advance to avoid races.
815 816
	 *
	 * In some cases we can be sure, that no new locks will be needed
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	 */
818 819 820 821 822 823
	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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	lock_kernel();
	if (request->fl_type != F_UNLCK) {
		for_each_lock(inode, before) {
828
			fl = *before;
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			if (!IS_POSIX(fl))
				continue;
			if (!posix_locks_conflict(request, fl))
				continue;
833
			if (conflock)
834
				__locks_copy_lock(conflock, fl);
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			error = -EAGAIN;
			if (!(request->fl_flags & FL_SLEEP))
				goto out;
			error = -EDEADLK;
			if (posix_locks_deadlock(request, fl))
				goto out;
841
			error = FILE_LOCK_DEFERRED;
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			locks_insert_block(fl, request);
			goto out;
  		}
  	}

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

	/*
	 * Find the first old lock with the same owner as the new lock.
	 */
	
	before = &inode->i_flock;

	/* First skip locks owned by other processes.  */
	while ((fl = *before) && (!IS_POSIX(fl) ||
				  !posix_same_owner(request, fl))) {
		before = &fl->fl_next;
	}

	/* Process locks with this owner.  */
	while ((fl = *before) && posix_same_owner(request, fl)) {
		/* Detect adjacent or overlapping regions (if same lock type)
		 */
		if (request->fl_type == fl->fl_type) {
O
Olaf Kirch 已提交
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			/* 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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			if (fl->fl_end < request->fl_start - 1)
				goto next_lock;
			/* If the next lock in the list has entirely bigger
			 * addresses than the new one, insert the lock here.
			 */
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Olaf Kirch 已提交
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			if (fl->fl_start - 1 > request->fl_end)
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Linus Torvalds 已提交
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				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) {
				locks_delete_lock(before);
				continue;
			}
			request = fl;
			added = 1;
		}
		else {
			/* Processing for different lock types is a bit
			 * more complex.
			 */
			if (fl->fl_end < request->fl_start)
				goto next_lock;
			if (fl->fl_start > request->fl_end)
				break;
			if (request->fl_type == F_UNLCK)
				added = 1;
			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) {
					locks_delete_lock(before);
					continue;
				}
				/* Replace the old lock with the new one.
				 * Wake up anybody waiting for the old one,
				 * as the change in lock type might satisfy
				 * their needs.
				 */
				locks_wake_up_blocks(fl);
				fl->fl_start = request->fl_start;
				fl->fl_end = request->fl_end;
				fl->fl_type = request->fl_type;
937 938
				locks_release_private(fl);
				locks_copy_private(fl, request);
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				request = fl;
				added = 1;
			}
		}
		/* Go on to next lock.
		 */
	next_lock:
		before = &fl->fl_next;
	}

949 950 951 952 953 954 955 956 957 958
	/*
	 * 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 bellow this, so it's safe yet to
	 * bail out.
	 */
	error = -ENOLCK; /* "no luck" */
	if (right && left == right && !new_fl2)
		goto out;

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	error = 0;
	if (!added) {
961 962 963
		if (request->fl_type == F_UNLCK) {
			if (request->fl_flags & FL_EXISTS)
				error = -ENOENT;
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Linus Torvalds 已提交
964
			goto out;
965
		}
966 967 968 969 970

		if (!new_fl) {
			error = -ENOLCK;
			goto out;
		}
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971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007
		locks_copy_lock(new_fl, request);
		locks_insert_lock(before, new_fl);
		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);
			locks_insert_lock(before, left);
		}
		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:
	unlock_kernel();
	/*
	 * Free any unused locks.
	 */
	if (new_fl)
		locks_free_lock(new_fl);
	if (new_fl2)
		locks_free_lock(new_fl2);
	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
1008
 * @conflock: Place to return a copy of the conflicting lock, if found.
L
Linus Torvalds 已提交
1009 1010 1011 1012
 *
 * 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
1013 1014 1015 1016
 *
 * 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
1017
 */
1018
int posix_lock_file(struct file *filp, struct file_lock *fl,
1019 1020
			struct file_lock *conflock)
{
1021
	return __posix_lock_file(filp->f_path.dentry->d_inode, fl, conflock);
L
Linus Torvalds 已提交
1022
}
1023
EXPORT_SYMBOL(posix_lock_file);
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1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038

/**
 * 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 (;;) {
1039
		error = posix_lock_file(filp, fl, NULL);
1040
		if (error != FILE_LOCK_DEFERRED)
L
Linus Torvalds 已提交
1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110
			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
 * @inode: the file to check
 *
 * Searches the inode's list of locks to find any POSIX locks which conflict.
 * This function is called from locks_verify_locked() only.
 */
int locks_mandatory_locked(struct inode *inode)
{
	fl_owner_t owner = current->files;
	struct file_lock *fl;

	/*
	 * Search the lock list for this inode for any POSIX locks.
	 */
	lock_kernel();
	for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
		if (!IS_POSIX(fl))
			continue;
		if (fl->fl_owner != owner)
			break;
	}
	unlock_kernel();
	return fl ? -EAGAIN : 0;
}

/**
 * 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;

	locks_init_lock(&fl);
	fl.fl_owner = current->files;
	fl.fl_pid = current->tgid;
	fl.fl_file = filp;
	fl.fl_flags = FL_POSIX | FL_ACCESS;
	if (filp && !(filp->f_flags & O_NONBLOCK))
		fl.fl_flags |= FL_SLEEP;
	fl.fl_type = (read_write == FLOCK_VERIFY_WRITE) ? F_WRLCK : F_RDLCK;
	fl.fl_start = offset;
	fl.fl_end = offset + count - 1;

	for (;;) {
1111
		error = __posix_lock_file(inode, &fl, NULL);
1112
		if (error != FILE_LOCK_DEFERRED)
L
Linus Torvalds 已提交
1113 1114 1115 1116 1117 1118 1119
			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.
			 */
1120
			if (__mandatory_lock(inode))
L
Linus Torvalds 已提交
1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171
				continue;
		}

		locks_delete_block(&fl);
		break;
	}

	return error;
}

EXPORT_SYMBOL(locks_mandatory_area);

/* We already had a lease on this file; just change its type */
int lease_modify(struct file_lock **before, int arg)
{
	struct file_lock *fl = *before;
	int error = assign_type(fl, arg);

	if (error)
		return error;
	locks_wake_up_blocks(fl);
	if (arg == F_UNLCK)
		locks_delete_lock(before);
	return 0;
}

EXPORT_SYMBOL(lease_modify);

static void time_out_leases(struct inode *inode)
{
	struct file_lock **before;
	struct file_lock *fl;

	before = &inode->i_flock;
	while ((fl = *before) && IS_LEASE(fl) && (fl->fl_type & F_INPROGRESS)) {
		if ((fl->fl_break_time == 0)
				|| time_before(jiffies, fl->fl_break_time)) {
			before = &fl->fl_next;
			continue;
		}
		lease_modify(before, fl->fl_type & ~F_INPROGRESS);
		if (fl == *before)	/* lease_modify may have freed fl */
			before = &fl->fl_next;
	}
}

/**
 *	__break_lease	-	revoke all outstanding leases on file
 *	@inode: the inode of the file to return
 *	@mode: the open mode (read or write)
 *
1172 1173 1174
 *	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
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1175 1176 1177 1178 1179 1180 1181 1182 1183 1184
 *	specified %O_NONBLOCK to your open().
 */
int __break_lease(struct inode *inode, unsigned int mode)
{
	int error = 0, future;
	struct file_lock *new_fl, *flock;
	struct file_lock *fl;
	unsigned long break_time;
	int i_have_this_lease = 0;

J
J. Bruce Fields 已提交
1185
	new_fl = lease_alloc(NULL, mode & FMODE_WRITE ? F_WRLCK : F_RDLCK);
L
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1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212

	lock_kernel();

	time_out_leases(inode);

	flock = inode->i_flock;
	if ((flock == NULL) || !IS_LEASE(flock))
		goto out;

	for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next)
		if (fl->fl_owner == current->files)
			i_have_this_lease = 1;

	if (mode & FMODE_WRITE) {
		/* If we want write access, we have to revoke any lease. */
		future = F_UNLCK | F_INPROGRESS;
	} else if (flock->fl_type & F_INPROGRESS) {
		/* If the lease is already being broken, we just leave it */
		future = flock->fl_type;
	} else if (flock->fl_type & F_WRLCK) {
		/* Downgrade the exclusive lease to a read-only lease. */
		future = F_RDLCK | F_INPROGRESS;
	} else {
		/* the existing lease was read-only, so we can read too. */
		goto out;
	}

J
J. Bruce Fields 已提交
1213 1214 1215
	if (IS_ERR(new_fl) && !i_have_this_lease
			&& ((mode & O_NONBLOCK) == 0)) {
		error = PTR_ERR(new_fl);
L
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1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246
		goto out;
	}

	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 */
	}

	for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
		if (fl->fl_type != future) {
			fl->fl_type = future;
			fl->fl_break_time = break_time;
			/* lease must have lmops break callback */
			fl->fl_lmops->fl_break(fl);
		}
	}

	if (i_have_this_lease || (mode & O_NONBLOCK)) {
		error = -EWOULDBLOCK;
		goto out;
	}

restart:
	break_time = flock->fl_break_time;
	if (break_time != 0) {
		break_time -= jiffies;
		if (break_time == 0)
			break_time++;
	}
1247 1248 1249 1250
	locks_insert_block(flock, new_fl);
	error = wait_event_interruptible_timeout(new_fl->fl_wait,
						!new_fl->fl_next, break_time);
	__locks_delete_block(new_fl);
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1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264
	if (error >= 0) {
		if (error == 0)
			time_out_leases(inode);
		/* Wait for the next lease that has not been broken yet */
		for (flock = inode->i_flock; flock && IS_LEASE(flock);
				flock = flock->fl_next) {
			if (flock->fl_type & F_INPROGRESS)
				goto restart;
		}
		error = 0;
	}

out:
	unlock_kernel();
J
J. Bruce Fields 已提交
1265
	if (!IS_ERR(new_fl))
L
Linus Torvalds 已提交
1266 1267 1268 1269 1270 1271 1272
		locks_free_lock(new_fl);
	return error;
}

EXPORT_SYMBOL(__break_lease);

/**
1273
 *	lease_get_mtime - get the last modified time of an inode
L
Linus Torvalds 已提交
1274 1275 1276 1277 1278
 *	@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
1279
 * exclusive lease, then they could be modifying it.
L
Linus Torvalds 已提交
1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320
 */
void lease_get_mtime(struct inode *inode, struct timespec *time)
{
	struct file_lock *flock = inode->i_flock;
	if (flock && IS_LEASE(flock) && (flock->fl_type & F_WRLCK))
		*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;
	int type = F_UNLCK;

	lock_kernel();
1321 1322
	time_out_leases(filp->f_path.dentry->d_inode);
	for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl);
L
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1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333
			fl = fl->fl_next) {
		if (fl->fl_file == filp) {
			type = fl->fl_type & ~F_INPROGRESS;
			break;
		}
	}
	unlock_kernel();
	return type;
}

/**
1334
 *	generic_setlease	-	sets a lease on an open file
L
Linus Torvalds 已提交
1335 1336 1337 1338 1339 1340 1341 1342 1343
 *	@filp: file pointer
 *	@arg: type of lease to obtain
 *	@flp: input - file_lock to use, output - file_lock inserted
 *
 *	The (input) flp->fl_lmops->fl_break function is required
 *	by break_lease().
 *
 *	Called with kernel lock held.
 */
1344
int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
L
Linus Torvalds 已提交
1345
{
1346
	struct file_lock *fl, **before, **my_before = NULL, *lease;
1347
	struct file_lock *new_fl = NULL;
1348
	struct dentry *dentry = filp->f_path.dentry;
L
Linus Torvalds 已提交
1349 1350 1351
	struct inode *inode = dentry->d_inode;
	int error, rdlease_count = 0, wrlease_count = 0;

1352
	if ((current_fsuid() != inode->i_uid) && !capable(CAP_LEASE))
1353 1354 1355 1356 1357 1358 1359
		return -EACCES;
	if (!S_ISREG(inode->i_mode))
		return -EINVAL;
	error = security_file_lock(filp, arg);
	if (error)
		return error;

L
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1360 1361
	time_out_leases(inode);

1362
	BUG_ON(!(*flp)->fl_lmops->fl_break);
L
Linus Torvalds 已提交
1363

1364 1365
	lease = *flp;

1366
	if (arg != F_UNLCK) {
1367 1368 1369 1370 1371
		error = -ENOMEM;
		new_fl = locks_alloc_lock();
		if (new_fl == NULL)
			goto out;

1372 1373 1374 1375 1376 1377 1378 1379
		error = -EAGAIN;
		if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
			goto out;
		if ((arg == F_WRLCK)
		    && ((atomic_read(&dentry->d_count) > 1)
			|| (atomic_read(&inode->i_count) > 1)))
			goto out;
	}
1380

L
Linus Torvalds 已提交
1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404
	/*
	 * 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.
	 */
	for (before = &inode->i_flock;
			((fl = *before) != NULL) && IS_LEASE(fl);
			before = &fl->fl_next) {
		if (lease->fl_lmops->fl_mylease(fl, lease))
			my_before = before;
		else if (fl->fl_type == (F_INPROGRESS | F_UNLCK))
			/*
			 * Someone is in the process of opening this
			 * file for writing so we may not take an
			 * exclusive lease on it.
			 */
			wrlease_count++;
		else
			rdlease_count++;
	}

1405
	error = -EAGAIN;
L
Linus Torvalds 已提交
1406 1407 1408 1409 1410
	if ((arg == F_RDLCK && (wrlease_count > 0)) ||
	    (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0)))
		goto out;

	if (my_before != NULL) {
1411
		*flp = *my_before;
L
Linus Torvalds 已提交
1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423
		error = lease->fl_lmops->fl_change(my_before, arg);
		goto out;
	}

	error = 0;
	if (arg == F_UNLCK)
		goto out;

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

1424 1425
	locks_copy_lock(new_fl, lease);
	locks_insert_lock(before, new_fl);
L
Linus Torvalds 已提交
1426

1427 1428
	*flp = new_fl;
	return 0;
L
Linus Torvalds 已提交
1429 1430

out:
1431 1432
	if (new_fl != NULL)
		locks_free_lock(new_fl);
L
Linus Torvalds 已提交
1433 1434
	return error;
}
1435
EXPORT_SYMBOL(generic_setlease);
L
Linus Torvalds 已提交
1436 1437

 /**
1438
 *	vfs_setlease        -       sets a lease on an open file
L
Linus Torvalds 已提交
1439 1440 1441 1442 1443
 *	@filp: file pointer
 *	@arg: type of lease to obtain
 *	@lease: file_lock to use
 *
 *	Call this to establish a lease on the file.
1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461
 *	The (*lease)->fl_lmops->fl_break operation must be set; if not,
 *	break_lease will oops!
 *
 *	This will call the filesystem's setlease file method, if
 *	defined.  Note that there is no getlease method; instead, the
 *	filesystem setlease method should call back to setlease() to
 *	add a lease to the inode's lease list, where fcntl_getlease() can
 *	find it.  Since fcntl_getlease() only reports whether the current
 *	task holds a lease, a cluster filesystem need only do this for
 *	leases held by processes on this node.
 *
 *	There is also no break_lease method; filesystems that
 *	handle their own leases shoud break leases themselves from the
 *	filesystem's open, create, and (on truncate) setattr methods.
 *
 *	Warning: the only current setlease methods exist only to disable
 *	leases in certain cases.  More vfs changes may be required to
 *	allow a full filesystem lease implementation.
L
Linus Torvalds 已提交
1462 1463
 */

1464
int vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
L
Linus Torvalds 已提交
1465 1466 1467 1468
{
	int error;

	lock_kernel();
1469 1470 1471
	if (filp->f_op && filp->f_op->setlease)
		error = filp->f_op->setlease(filp, arg, lease);
	else
1472
		error = generic_setlease(filp, arg, lease);
L
Linus Torvalds 已提交
1473 1474 1475 1476
	unlock_kernel();

	return error;
}
1477
EXPORT_SYMBOL_GPL(vfs_setlease);
L
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1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491

/**
 *	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)
{
	struct file_lock fl, *flp = &fl;
1492
	struct inode *inode = filp->f_path.dentry->d_inode;
L
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1493 1494 1495 1496 1497 1498 1499 1500 1501
	int error;

	locks_init_lock(&fl);
	error = lease_init(filp, arg, &fl);
	if (error)
		return error;

	lock_kernel();

1502
	error = vfs_setlease(filp, arg, &flp);
1503
	if (error || arg == F_UNLCK)
L
Linus Torvalds 已提交
1504 1505 1506 1507
		goto out_unlock;

	error = fasync_helper(fd, filp, 1, &flp->fl_fasync);
	if (error < 0) {
1508
		/* remove lease just inserted by setlease */
L
Linus Torvalds 已提交
1509
		flp->fl_type = F_UNLCK | F_INPROGRESS;
1510
		flp->fl_break_time = jiffies - 10;
L
Linus Torvalds 已提交
1511 1512 1513 1514
		time_out_leases(inode);
		goto out_unlock;
	}

1515
	error = __f_setown(filp, task_pid(current), PIDTYPE_PID, 0);
L
Linus Torvalds 已提交
1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533
out_unlock:
	unlock_kernel();
	return error;
}

/**
 * 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);
1534
		if (error != FILE_LOCK_DEFERRED)
L
Linus Torvalds 已提交
1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566
			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.
 */
1567
SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
L
Linus Torvalds 已提交
1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582
{
	struct file *filp;
	struct file_lock *lock;
	int can_sleep, unlock;
	int error;

	error = -EBADF;
	filp = fget(fd);
	if (!filp)
		goto out;

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

1583 1584
	if (!unlock && !(cmd & LOCK_MAND) &&
	    !(filp->f_mode & (FMODE_READ|FMODE_WRITE)))
L
Linus Torvalds 已提交
1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604
		goto out_putf;

	error = flock_make_lock(filp, &lock, cmd);
	if (error)
		goto out_putf;
	if (can_sleep)
		lock->fl_flags |= FL_SLEEP;

	error = security_file_lock(filp, cmd);
	if (error)
		goto out_free;

	if (filp->f_op && filp->f_op->flock)
		error = filp->f_op->flock(filp,
					  (can_sleep) ? F_SETLKW : F_SETLK,
					  lock);
	else
		error = flock_lock_file_wait(filp, lock);

 out_free:
1605
	locks_free_lock(lock);
L
Linus Torvalds 已提交
1606 1607 1608 1609 1610 1611 1612

 out_putf:
	fput(filp);
 out:
	return error;
}

1613 1614 1615
/**
 * vfs_test_lock - test file byte range lock
 * @filp: The file to test lock for
1616
 * @fl: The lock to test; also used to hold result
1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629
 *
 * 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)
{
	if (filp->f_op && filp->f_op->lock)
		return filp->f_op->lock(filp, F_GETLK, fl);
	posix_test_lock(filp, fl);
	return 0;
}
EXPORT_SYMBOL_GPL(vfs_test_lock);

1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646
static int posix_lock_to_flock(struct flock *flock, struct file_lock *fl)
{
	flock->l_pid = fl->fl_pid;
#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;
1647
	flock->l_type = fl->fl_type;
1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662
	return 0;
}

#if BITS_PER_LONG == 32
static void posix_lock_to_flock64(struct flock64 *flock, struct file_lock *fl)
{
	flock->l_pid = fl->fl_pid;
	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
1663 1664 1665 1666 1667
/* Report the first existing lock that would conflict with l.
 * This implements the F_GETLK command of fcntl().
 */
int fcntl_getlk(struct file *filp, struct flock __user *l)
{
1668
	struct file_lock file_lock;
L
Linus Torvalds 已提交
1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682
	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;

1683 1684 1685
	error = vfs_test_lock(filp, &file_lock);
	if (error)
		goto out;
L
Linus Torvalds 已提交
1686
 
1687 1688 1689
	flock.l_type = file_lock.fl_type;
	if (file_lock.fl_type != F_UNLCK) {
		error = posix_lock_to_flock(&flock, &file_lock);
1690
		if (error)
L
Linus Torvalds 已提交
1691 1692 1693 1694 1695 1696 1697 1698 1699
			goto out;
	}
	error = -EFAULT;
	if (!copy_to_user(l, &flock, sizeof(flock)))
		error = 0;
out:
	return error;
}

1700 1701 1702 1703 1704
/**
 * 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
1705 1706 1707 1708 1709 1710 1711 1712
 * @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.
1713 1714 1715 1716 1717 1718 1719
 *
 * 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)
 * fl_grant is set. Callers expecting ->lock() to return asynchronously
 * 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,
1720
 * it must return FILE_LOCK_DEFERRED, and call ->fl_grant() when the lock
1721 1722
 * request completes.
 * If the request is for non-blocking lock the file system should return
1723 1724
 * 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
1725 1726 1727 1728 1729
 * 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
1730
 * ->fl_grant() before returning to the caller with a FILE_LOCK_DEFERRED
1731
 * return code.
1732
 */
1733
int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
1734 1735 1736 1737
{
	if (filp->f_op && filp->f_op->lock)
		return filp->f_op->lock(filp, cmd, fl);
	else
1738
		return posix_lock_file(filp, fl, conf);
1739 1740 1741
}
EXPORT_SYMBOL_GPL(vfs_lock_file);

M
Miklos Szeredi 已提交
1742 1743 1744 1745 1746 1747 1748 1749 1750
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;

1751 1752 1753
	for (;;) {
		error = vfs_lock_file(filp, cmd, fl, NULL);
		if (error != FILE_LOCK_DEFERRED)
M
Miklos Szeredi 已提交
1754
			break;
1755 1756 1757 1758 1759 1760
		error = wait_event_interruptible(fl->fl_wait, !fl->fl_next);
		if (!error)
			continue;

		locks_delete_block(fl);
		break;
M
Miklos Szeredi 已提交
1761 1762 1763 1764 1765
	}

	return error;
}

L
Linus Torvalds 已提交
1766 1767 1768
/* Apply the lock described by l to an open file descriptor.
 * This implements both the F_SETLK and F_SETLKW commands of fcntl().
 */
1769 1770
int fcntl_setlk(unsigned int fd, struct file *filp, unsigned int cmd,
		struct flock __user *l)
L
Linus Torvalds 已提交
1771 1772 1773 1774
{
	struct file_lock *file_lock = locks_alloc_lock();
	struct flock flock;
	struct inode *inode;
1775
	struct file *f;
L
Linus Torvalds 已提交
1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787
	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;

1788
	inode = filp->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1789 1790 1791 1792

	/* Don't allow mandatory locks on files that may be memory mapped
	 * and shared.
	 */
1793
	if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
L
Linus Torvalds 已提交
1794 1795 1796 1797
		error = -EAGAIN;
		goto out;
	}

1798
again:
L
Linus Torvalds 已提交
1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822
	error = flock_to_posix_lock(filp, file_lock, &flock);
	if (error)
		goto out;
	if (cmd == F_SETLKW) {
		file_lock->fl_flags |= FL_SLEEP;
	}
	
	error = -EBADF;
	switch (flock.l_type) {
	case F_RDLCK:
		if (!(filp->f_mode & FMODE_READ))
			goto out;
		break;
	case F_WRLCK:
		if (!(filp->f_mode & FMODE_WRITE))
			goto out;
		break;
	case F_UNLCK:
		break;
	default:
		error = -EINVAL;
		goto out;
	}

M
Miklos Szeredi 已提交
1823
	error = do_lock_file_wait(filp, cmd, file_lock);
L
Linus Torvalds 已提交
1824

1825 1826 1827 1828
	/*
	 * Attempt to detect a close/fcntl race and recover by
	 * releasing the lock that was just acquired.
	 */
1829 1830 1831 1832 1833 1834 1835 1836 1837
	/*
	 * we need that spin_lock here - it prevents reordering between
	 * update of inode->i_flock and check for it done in close().
	 * 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) {
1838 1839
		flock.l_type = F_UNLCK;
		goto again;
L
Linus Torvalds 已提交
1840 1841
	}

1842
out:
L
Linus Torvalds 已提交
1843 1844 1845 1846 1847 1848 1849 1850 1851 1852
	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().
 */
int fcntl_getlk64(struct file *filp, struct flock64 __user *l)
{
1853
	struct file_lock file_lock;
L
Linus Torvalds 已提交
1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867
	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;

1868 1869 1870 1871
	error = vfs_test_lock(filp, &file_lock);
	if (error)
		goto out;

1872 1873 1874 1875
	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
1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886
	error = -EFAULT;
	if (!copy_to_user(l, &flock, sizeof(flock)))
		error = 0;
  
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().
 */
1887 1888
int fcntl_setlk64(unsigned int fd, struct file *filp, unsigned int cmd,
		struct flock64 __user *l)
L
Linus Torvalds 已提交
1889 1890 1891 1892
{
	struct file_lock *file_lock = locks_alloc_lock();
	struct flock64 flock;
	struct inode *inode;
1893
	struct file *f;
L
Linus Torvalds 已提交
1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905
	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;

1906
	inode = filp->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1907 1908 1909 1910

	/* Don't allow mandatory locks on files that may be memory mapped
	 * and shared.
	 */
1911
	if (mandatory_lock(inode) && mapping_writably_mapped(filp->f_mapping)) {
L
Linus Torvalds 已提交
1912 1913 1914 1915
		error = -EAGAIN;
		goto out;
	}

1916
again:
L
Linus Torvalds 已提交
1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940
	error = flock64_to_posix_lock(filp, file_lock, &flock);
	if (error)
		goto out;
	if (cmd == F_SETLKW64) {
		file_lock->fl_flags |= FL_SLEEP;
	}
	
	error = -EBADF;
	switch (flock.l_type) {
	case F_RDLCK:
		if (!(filp->f_mode & FMODE_READ))
			goto out;
		break;
	case F_WRLCK:
		if (!(filp->f_mode & FMODE_WRITE))
			goto out;
		break;
	case F_UNLCK:
		break;
	default:
		error = -EINVAL;
		goto out;
	}

M
Miklos Szeredi 已提交
1941
	error = do_lock_file_wait(filp, cmd, file_lock);
L
Linus Torvalds 已提交
1942

1943 1944 1945 1946
	/*
	 * Attempt to detect a close/fcntl race and recover by
	 * releasing the lock that was just acquired.
	 */
1947 1948 1949 1950
	spin_lock(&current->files->file_lock);
	f = fcheck(fd);
	spin_unlock(&current->files->file_lock);
	if (!error && f != filp && flock.l_type != F_UNLCK) {
1951 1952
		flock.l_type = F_UNLCK;
		goto again;
L
Linus Torvalds 已提交
1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 1965 1966 1967
	}

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)
{
1968
	struct file_lock lock;
L
Linus Torvalds 已提交
1969 1970 1971 1972 1973 1974

	/*
	 * 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.
	 */
1975
	if (!filp->f_path.dentry->d_inode->i_flock)
L
Linus Torvalds 已提交
1976 1977 1978
		return;

	lock.fl_type = F_UNLCK;
1979
	lock.fl_flags = FL_POSIX | FL_CLOSE;
L
Linus Torvalds 已提交
1980 1981 1982 1983 1984 1985 1986 1987
	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;

1988
	vfs_lock_file(filp, F_SETLK, &lock, NULL);
L
Linus Torvalds 已提交
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000

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

EXPORT_SYMBOL(locks_remove_posix);

/*
 * This function is called on the last close of an open file.
 */
void locks_remove_flock(struct file *filp)
{
2001
	struct inode * inode = filp->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
	struct file_lock *fl;
	struct file_lock **before;

	if (!inode->i_flock)
		return;

	if (filp->f_op && filp->f_op->flock) {
		struct file_lock fl = {
			.fl_pid = current->tgid,
			.fl_file = filp,
			.fl_flags = FL_FLOCK,
			.fl_type = F_UNLCK,
			.fl_end = OFFSET_MAX,
		};
		filp->f_op->flock(filp, F_SETLKW, &fl);
2017 2018
		if (fl.fl_ops && fl.fl_ops->fl_release_private)
			fl.fl_ops->fl_release_private(&fl);
L
Linus Torvalds 已提交
2019 2020 2021 2022 2023 2024 2025
	}

	lock_kernel();
	before = &inode->i_flock;

	while ((fl = *before) != NULL) {
		if (fl->fl_file == filp) {
2026
			if (IS_FLOCK(fl)) {
L
Linus Torvalds 已提交
2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042 2043 2044 2045 2046 2047 2048
				locks_delete_lock(before);
				continue;
			}
			if (IS_LEASE(fl)) {
				lease_modify(before, F_UNLCK);
				continue;
			}
			/* What? */
			BUG();
 		}
		before = &fl->fl_next;
	}
	unlock_kernel();
}

/**
 *	posix_unblock_lock - stop waiting for a file lock
 *      @filp:   how the file was opened
 *	@waiter: the lock which was waiting
 *
 *	lockd needs to block waiting for locks.
 */
J
J. Bruce Fields 已提交
2049
int
L
Linus Torvalds 已提交
2050 2051
posix_unblock_lock(struct file *filp, struct file_lock *waiter)
{
J
J. Bruce Fields 已提交
2052 2053
	int status = 0;

L
Linus Torvalds 已提交
2054
	lock_kernel();
2055
	if (waiter->fl_next)
L
Linus Torvalds 已提交
2056
		__locks_delete_block(waiter);
J
J. Bruce Fields 已提交
2057 2058
	else
		status = -ENOENT;
2059
	unlock_kernel();
J
J. Bruce Fields 已提交
2060
	return status;
L
Linus Torvalds 已提交
2061 2062 2063 2064
}

EXPORT_SYMBOL(posix_unblock_lock);

M
Marc Eshel 已提交
2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075 2076 2077 2078 2079 2080
/**
 * 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)
{
	if (filp->f_op && filp->f_op->lock)
		return filp->f_op->lock(filp, F_CANCELLK, fl);
	return 0;
}

EXPORT_SYMBOL_GPL(vfs_cancel_lock);

2081
#ifdef CONFIG_PROC_FS
2082
#include <linux/proc_fs.h>
2083 2084 2085 2086
#include <linux/seq_file.h>

static void lock_get_status(struct seq_file *f, struct file_lock *fl,
							int id, char *pfx)
L
Linus Torvalds 已提交
2087 2088
{
	struct inode *inode = NULL;
2089 2090 2091
	unsigned int fl_pid;

	if (fl->fl_nspid)
2092
		fl_pid = pid_vnr(fl->fl_nspid);
2093 2094
	else
		fl_pid = fl->fl_pid;
L
Linus Torvalds 已提交
2095 2096

	if (fl->fl_file != NULL)
2097
		inode = fl->fl_file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
2098

2099
	seq_printf(f, "%d:%s ", id, pfx);
L
Linus Torvalds 已提交
2100
	if (IS_POSIX(fl)) {
2101
		seq_printf(f, "%6s %s ",
L
Linus Torvalds 已提交
2102 2103
			     (fl->fl_flags & FL_ACCESS) ? "ACCESS" : "POSIX ",
			     (inode == NULL) ? "*NOINODE*" :
2104
			     mandatory_lock(inode) ? "MANDATORY" : "ADVISORY ");
L
Linus Torvalds 已提交
2105 2106
	} else if (IS_FLOCK(fl)) {
		if (fl->fl_type & LOCK_MAND) {
2107
			seq_printf(f, "FLOCK  MSNFS     ");
L
Linus Torvalds 已提交
2108
		} else {
2109
			seq_printf(f, "FLOCK  ADVISORY  ");
L
Linus Torvalds 已提交
2110 2111
		}
	} else if (IS_LEASE(fl)) {
2112
		seq_printf(f, "LEASE  ");
L
Linus Torvalds 已提交
2113
		if (fl->fl_type & F_INPROGRESS)
2114
			seq_printf(f, "BREAKING  ");
L
Linus Torvalds 已提交
2115
		else if (fl->fl_file)
2116
			seq_printf(f, "ACTIVE    ");
L
Linus Torvalds 已提交
2117
		else
2118
			seq_printf(f, "BREAKER   ");
L
Linus Torvalds 已提交
2119
	} else {
2120
		seq_printf(f, "UNKNOWN UNKNOWN  ");
L
Linus Torvalds 已提交
2121 2122
	}
	if (fl->fl_type & LOCK_MAND) {
2123
		seq_printf(f, "%s ",
L
Linus Torvalds 已提交
2124 2125 2126 2127
			       (fl->fl_type & LOCK_READ)
			       ? (fl->fl_type & LOCK_WRITE) ? "RW   " : "READ "
			       : (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
	} else {
2128
		seq_printf(f, "%s ",
L
Linus Torvalds 已提交
2129 2130 2131 2132 2133 2134
			       (fl->fl_type & F_INPROGRESS)
			       ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ "
			       : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
	}
	if (inode) {
#ifdef WE_CAN_BREAK_LSLK_NOW
2135
		seq_printf(f, "%d %s:%ld ", fl_pid,
L
Linus Torvalds 已提交
2136 2137 2138
				inode->i_sb->s_id, inode->i_ino);
#else
		/* userspace relies on this representation of dev_t ;-( */
2139
		seq_printf(f, "%d %02x:%02x:%ld ", fl_pid,
L
Linus Torvalds 已提交
2140 2141 2142 2143
				MAJOR(inode->i_sb->s_dev),
				MINOR(inode->i_sb->s_dev), inode->i_ino);
#endif
	} else {
2144
		seq_printf(f, "%d <none>:0 ", fl_pid);
L
Linus Torvalds 已提交
2145 2146 2147
	}
	if (IS_POSIX(fl)) {
		if (fl->fl_end == OFFSET_MAX)
2148
			seq_printf(f, "%Ld EOF\n", fl->fl_start);
L
Linus Torvalds 已提交
2149
		else
2150
			seq_printf(f, "%Ld %Ld\n", fl->fl_start, fl->fl_end);
L
Linus Torvalds 已提交
2151
	} else {
2152
		seq_printf(f, "0 EOF\n");
L
Linus Torvalds 已提交
2153 2154 2155
	}
}

2156
static int locks_show(struct seq_file *f, void *v)
L
Linus Torvalds 已提交
2157
{
2158
	struct file_lock *fl, *bfl;
L
Linus Torvalds 已提交
2159

2160
	fl = list_entry(v, struct file_lock, fl_link);
L
Linus Torvalds 已提交
2161

2162
	lock_get_status(f, fl, (long)f->private, "");
L
Linus Torvalds 已提交
2163

2164 2165
	list_for_each_entry(bfl, &fl->fl_block, fl_block)
		lock_get_status(f, bfl, (long)f->private, " ->");
2166

2167 2168 2169
	f->private++;
	return 0;
}
L
Linus Torvalds 已提交
2170

2171 2172 2173 2174 2175 2176
static void *locks_start(struct seq_file *f, loff_t *pos)
{
	lock_kernel();
	f->private = (void *)1;
	return seq_list_start(&file_lock_list, *pos);
}
L
Linus Torvalds 已提交
2177

2178 2179 2180 2181
static void *locks_next(struct seq_file *f, void *v, loff_t *pos)
{
	return seq_list_next(v, &file_lock_list, pos);
}
L
Linus Torvalds 已提交
2182

2183 2184
static void locks_stop(struct seq_file *f, void *v)
{
L
Linus Torvalds 已提交
2185 2186 2187
	unlock_kernel();
}

2188
static const struct seq_operations locks_seq_operations = {
2189 2190 2191 2192 2193
	.start	= locks_start,
	.next	= locks_next,
	.stop	= locks_stop,
	.show	= locks_show,
};
2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205 2206 2207 2208 2209 2210 2211 2212

static int locks_open(struct inode *inode, struct file *filp)
{
	return seq_open(filp, &locks_seq_operations);
}

static const struct file_operations proc_locks_operations = {
	.open		= locks_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= seq_release,
};

static int __init proc_locks_init(void)
{
	proc_create("locks", 0, NULL, &proc_locks_operations);
	return 0;
}
module_init(proc_locks_init);
2213 2214
#endif

L
Linus Torvalds 已提交
2215 2216 2217 2218 2219 2220 2221 2222 2223 2224 2225 2226 2227 2228 2229 2230 2231 2232 2233 2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259 2260 2261 2262 2263 2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276 2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295 2296
/**
 *	lock_may_read - checks that the region is free of locks
 *	@inode: the inode that is being read
 *	@start: the first byte to read
 *	@len: the number of bytes to read
 *
 *	Emulates Windows locking requirements.  Whole-file
 *	mandatory locks (share modes) can prohibit a read and
 *	byte-range POSIX locks can prohibit a read if they overlap.
 *
 *	N.B. this function is only ever called
 *	from knfsd and ownership of locks is never checked.
 */
int lock_may_read(struct inode *inode, loff_t start, unsigned long len)
{
	struct file_lock *fl;
	int result = 1;
	lock_kernel();
	for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
		if (IS_POSIX(fl)) {
			if (fl->fl_type == F_RDLCK)
				continue;
			if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
				continue;
		} else if (IS_FLOCK(fl)) {
			if (!(fl->fl_type & LOCK_MAND))
				continue;
			if (fl->fl_type & LOCK_READ)
				continue;
		} else
			continue;
		result = 0;
		break;
	}
	unlock_kernel();
	return result;
}

EXPORT_SYMBOL(lock_may_read);

/**
 *	lock_may_write - checks that the region is free of locks
 *	@inode: the inode that is being written
 *	@start: the first byte to write
 *	@len: the number of bytes to write
 *
 *	Emulates Windows locking requirements.  Whole-file
 *	mandatory locks (share modes) can prohibit a write and
 *	byte-range POSIX locks can prohibit a write if they overlap.
 *
 *	N.B. this function is only ever called
 *	from knfsd and ownership of locks is never checked.
 */
int lock_may_write(struct inode *inode, loff_t start, unsigned long len)
{
	struct file_lock *fl;
	int result = 1;
	lock_kernel();
	for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
		if (IS_POSIX(fl)) {
			if ((fl->fl_end < start) || (fl->fl_start > (start + len)))
				continue;
		} else if (IS_FLOCK(fl)) {
			if (!(fl->fl_type & LOCK_MAND))
				continue;
			if (fl->fl_type & LOCK_WRITE)
				continue;
		} else
			continue;
		result = 0;
		break;
	}
	unlock_kernel();
	return result;
}

EXPORT_SYMBOL(lock_may_write);

static int __init filelock_init(void)
{
	filelock_cache = kmem_cache_create("file_lock_cache",
			sizeof(struct file_lock), 0, SLAB_PANIC,
2297
			init_once);
L
Linus Torvalds 已提交
2298 2299 2300 2301
	return 0;
}

core_initcall(filelock_init);