*
* 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.
+ * See 'Documentation/filesystems/mandatory-locking.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
#define IS_FLOCK(fl) (fl->fl_flags & FL_FLOCK)
#define IS_LEASE(fl) (fl->fl_flags & FL_LEASE)
+static bool lease_breaking(struct file_lock *fl)
+{
+ 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;
+}
+
int leases_enable = 1;
int lease_break_time = 45;
static struct kmem_cache *filelock_cache __read_mostly;
-static void locks_init_lock_always(struct file_lock *fl)
+static void locks_init_lock_heads(struct file_lock *fl)
{
- fl->fl_next = NULL;
- fl->fl_fasync = NULL;
- fl->fl_owner = NULL;
- fl->fl_pid = 0;
- fl->fl_nspid = NULL;
- fl->fl_file = NULL;
- fl->fl_flags = 0;
- fl->fl_type = 0;
- fl->fl_start = fl->fl_end = 0;
+ INIT_LIST_HEAD(&fl->fl_link);
+ INIT_LIST_HEAD(&fl->fl_block);
+ init_waitqueue_head(&fl->fl_wait);
}
/* Allocate an empty lock structure. */
struct file_lock *locks_alloc_lock(void)
{
- struct file_lock *fl = kmem_cache_alloc(filelock_cache, GFP_KERNEL);
+ struct file_lock *fl = kmem_cache_zalloc(filelock_cache, GFP_KERNEL);
if (fl)
- locks_init_lock_always(fl);
+ locks_init_lock_heads(fl);
return fl;
}
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;
- }
+ fl->fl_lmops = NULL;
}
EXPORT_SYMBOL_GPL(locks_release_private);
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_ops = NULL;
- fl->fl_lmops = NULL;
- locks_init_lock_always(fl);
+ memset(fl, 0, sizeof(struct file_lock));
+ locks_init_lock_heads(fl);
}
EXPORT_SYMBOL(locks_init_lock);
-/*
- * Initialises the fields of the file lock which are invariant for
- * free file_locks.
- */
-static void init_once(void *foo)
-{
- struct file_lock *lock = (struct file_lock *) foo;
-
- locks_init_lock(lock);
-}
-
static void locks_copy_private(struct file_lock *new, struct file_lock *fl)
{
if (fl->fl_ops) {
return 0;
}
-static int assign_type(struct file_lock *fl, int type)
+static int assign_type(struct file_lock *fl, long type)
{
switch (type) {
case F_RDLCK:
start = filp->f_pos;
break;
case SEEK_END:
- start = i_size_read(filp->f_path.dentry->d_inode);
+ start = i_size_read(file_inode(filp));
break;
default:
return -EINVAL;
start = filp->f_pos;
break;
case SEEK_END:
- start = i_size_read(filp->f_path.dentry->d_inode);
+ start = i_size_read(file_inode(filp));
break;
default:
return -EINVAL;
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;
-}
-
static const struct lock_manager_operations lease_manager_ops = {
- .fl_break = lease_break_callback,
- .fl_release_private = lease_release_private_callback,
- .fl_change = lease_modify,
+ .lm_break = lease_break_callback,
+ .lm_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)
+static int lease_init(struct file *filp, long type, struct file_lock *fl)
{
if (assign_type(fl, type) != 0)
return -EINVAL;
}
/* Allocate a file_lock initialised to this type of lease */
-static struct file_lock *lease_alloc(struct file *filp, int type)
+static struct file_lock *lease_alloc(struct file *filp, long type)
{
struct file_lock *fl = locks_alloc_lock();
int error = -ENOMEM;
*/
static int posix_same_owner(struct file_lock *fl1, struct file_lock *fl2)
{
- if (fl1->fl_lmops && fl1->fl_lmops->fl_compare_owner)
+ if (fl1->fl_lmops && fl1->fl_lmops->lm_compare_owner)
return fl2->fl_lmops == fl1->fl_lmops &&
- fl1->fl_lmops->fl_compare_owner(fl1, fl2);
+ fl1->fl_lmops->lm_compare_owner(fl1, fl2);
return fl1->fl_owner == fl2->fl_owner;
}
/*
*/
-static void locks_delete_block(struct file_lock *waiter)
+void locks_delete_block(struct file_lock *waiter)
{
lock_flocks();
__locks_delete_block(waiter);
unlock_flocks();
}
+EXPORT_SYMBOL(locks_delete_block);
/* Insert waiter into blocker's block list.
* We use a circular list so that processes can be easily woken up in
waiter = list_first_entry(&blocker->fl_block,
struct file_lock, fl_block);
__locks_delete_block(waiter);
- if (waiter->fl_lmops && waiter->fl_lmops->fl_notify)
- waiter->fl_lmops->fl_notify(waiter);
+ if (waiter->fl_lmops && waiter->fl_lmops->lm_notify)
+ waiter->fl_lmops->lm_notify(waiter);
else
wake_up(&waiter->fl_wait);
}
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;
- }
-
if (fl->fl_nspid) {
put_pid(fl->fl_nspid);
fl->fl_nspid = NULL;
struct file_lock *cfl;
lock_flocks();
- for (cfl = filp->f_path.dentry->d_inode->i_flock; cfl; cfl = cfl->fl_next) {
+ for (cfl = file_inode(filp)->i_flock; cfl; cfl = cfl->fl_next) {
if (!IS_POSIX(cfl))
continue;
if (posix_locks_conflict(fl, cfl))
{
struct file_lock *new_fl = NULL;
struct file_lock **before;
- struct inode * inode = filp->f_path.dentry->d_inode;
+ struct inode * inode = file_inode(filp);
int error = 0;
int found = 0;
int posix_lock_file(struct file *filp, struct file_lock *fl,
struct file_lock *conflock)
{
- return __posix_lock_file(filp->f_path.dentry->d_inode, fl, conflock);
+ return __posix_lock_file(file_inode(filp), fl, conflock);
}
EXPORT_SYMBOL(posix_lock_file);
EXPORT_SYMBOL(locks_mandatory_area);
+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;
+ }
+}
+
/* We already had a lease on this file; just change its type */
int lease_modify(struct file_lock **before, int arg)
{
if (error)
return error;
+ lease_clear_pending(fl, arg);
locks_wake_up_blocks(fl);
- if (arg == F_UNLCK)
+ if (arg == F_UNLCK) {
+ struct file *filp = fl->fl_file;
+
+ f_delown(filp);
+ filp->f_owner.signum = 0;
+ 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;
+ }
locks_delete_lock(before);
+ }
return 0;
}
EXPORT_SYMBOL(lease_modify);
+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);
+}
+
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);
+ while ((fl = *before) && IS_LEASE(fl) && lease_breaking(fl)) {
+ if (past_time(fl->fl_downgrade_time))
+ lease_modify(before, F_RDLCK);
+ if (past_time(fl->fl_break_time))
+ lease_modify(before, F_UNLCK);
if (fl == *before) /* lease_modify may have freed fl */
before = &fl->fl_next;
}
*/
int __break_lease(struct inode *inode, unsigned int mode)
{
- int error = 0, future;
+ int error = 0;
struct file_lock *new_fl, *flock;
struct file_lock *fl;
unsigned long break_time;
int want_write = (mode & O_ACCMODE) != O_RDONLY;
new_fl = lease_alloc(NULL, want_write ? F_WRLCK : F_RDLCK);
+ if (IS_ERR(new_fl))
+ return PTR_ERR(new_fl);
lock_flocks();
if ((flock == NULL) || !IS_LEASE(flock))
goto out;
+ if (!locks_conflict(flock, new_fl))
+ 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 (want_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;
- }
-
- if (IS_ERR(new_fl) && !i_have_this_lease
- && ((mode & O_NONBLOCK) == 0)) {
- error = PTR_ERR(new_fl);
- goto out;
- }
-
break_time = 0;
if (lease_break_time > 0) {
break_time = jiffies + lease_break_time * HZ;
}
for (fl = flock; fl && IS_LEASE(fl); fl = fl->fl_next) {
- if (fl->fl_type != future) {
- fl->fl_type = future;
+ if (want_write) {
+ if (fl->fl_flags & FL_UNLOCK_PENDING)
+ continue;
+ fl->fl_flags |= FL_UNLOCK_PENDING;
fl->fl_break_time = break_time;
- /* lease must have lmops break callback */
- fl->fl_lmops->fl_break(fl);
+ } else {
+ if (lease_breaking(flock))
+ continue;
+ fl->fl_flags |= FL_DOWNGRADE_PENDING;
+ fl->fl_downgrade_time = break_time;
}
+ fl->fl_lmops->lm_break(fl);
}
if (i_have_this_lease || (mode & O_NONBLOCK)) {
restart:
break_time = flock->fl_break_time;
- if (break_time != 0) {
+ if (break_time != 0)
break_time -= jiffies;
- if (break_time == 0)
- break_time++;
- }
+ if (break_time == 0)
+ break_time++;
locks_insert_block(flock, new_fl);
unlock_flocks();
error = wait_event_interruptible_timeout(new_fl->fl_wait,
if (error >= 0) {
if (error == 0)
time_out_leases(inode);
- /* Wait for the next lease that has not been broken yet */
+ /*
+ * Wait for the next conflicting 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)
+ if (locks_conflict(new_fl, flock))
goto restart;
}
error = 0;
out:
unlock_flocks();
- if (!IS_ERR(new_fl))
- locks_free_lock(new_fl);
+ locks_free_lock(new_fl);
return error;
}
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))
+ if (flock && IS_LEASE(flock) && (flock->fl_type == F_WRLCK))
*time = current_fs_time(inode->i_sb);
else
*time = inode->i_mtime;
int type = F_UNLCK;
lock_flocks();
- time_out_leases(filp->f_path.dentry->d_inode);
- for (fl = filp->f_path.dentry->d_inode->i_flock; fl && IS_LEASE(fl);
+ time_out_leases(file_inode(filp));
+ for (fl = file_inode(filp)->i_flock; fl && IS_LEASE(fl);
fl = fl->fl_next) {
if (fl->fl_file == filp) {
- type = fl->fl_type & ~F_INPROGRESS;
+ type = target_leasetype(fl);
break;
}
}
return type;
}
-/**
- * generic_setlease - sets a lease on an open file
- * @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 file_lock_lock held.
- */
-int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
+int generic_add_lease(struct file *filp, long arg, struct file_lock **flp)
{
struct file_lock *fl, **before, **my_before = NULL, *lease;
struct dentry *dentry = filp->f_path.dentry;
struct inode *inode = dentry->d_inode;
- int error, rdlease_count = 0, wrlease_count = 0;
+ int error;
lease = *flp;
- error = -EACCES;
- if ((current_fsuid() != inode->i_uid) && !capable(CAP_LEASE))
- goto out;
- error = -EINVAL;
- if (!S_ISREG(inode->i_mode))
+ error = -EAGAIN;
+ if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
goto out;
- error = security_file_lock(filp, arg);
- if (error)
+ if ((arg == F_WRLCK)
+ && ((dentry->d_count > 1)
+ || (atomic_read(&inode->i_count) > 1)))
goto out;
- time_out_leases(inode);
-
- BUG_ON(!(*flp)->fl_lmops->fl_break);
-
- if (arg != F_UNLCK) {
- error = -EAGAIN;
- if ((arg == F_RDLCK) && (atomic_read(&inode->i_writecount) > 0))
- goto out;
- if ((arg == F_WRLCK)
- && ((dentry->d_count > 1)
- || (atomic_read(&inode->i_count) > 1)))
- goto out;
- }
-
/*
* At this point, we know that if there is an exclusive
* lease on this file, then we hold it on this filp
* then the file is not open by anyone (including us)
* except for this filp.
*/
+ error = -EAGAIN;
for (before = &inode->i_flock;
((fl = *before) != NULL) && IS_LEASE(fl);
before = &fl->fl_next) {
- if (fl->fl_file == filp)
+ if (fl->fl_file == filp) {
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++;
+ continue;
+ }
+ /*
+ * 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;
}
- error = -EAGAIN;
- if ((arg == F_RDLCK && (wrlease_count > 0)) ||
- (arg == F_WRLCK && ((rdlease_count + wrlease_count) > 0)))
- goto out;
-
if (my_before != NULL) {
- error = lease->fl_lmops->fl_change(my_before, arg);
+ error = lease->fl_lmops->lm_change(my_before, arg);
if (!error)
*flp = *my_before;
goto out;
}
- if (arg == F_UNLCK)
- goto out;
-
error = -EINVAL;
if (!leases_enable)
goto out;
out:
return error;
}
+
+int generic_delete_lease(struct file *filp, struct file_lock **flp)
+{
+ struct file_lock *fl, **before;
+ struct dentry *dentry = filp->f_path.dentry;
+ struct inode *inode = dentry->d_inode;
+
+ for (before = &inode->i_flock;
+ ((fl = *before) != NULL) && IS_LEASE(fl);
+ before = &fl->fl_next) {
+ if (fl->fl_file != filp)
+ continue;
+ return (*flp)->fl_lmops->lm_change(before, F_UNLCK);
+ }
+ return -EAGAIN;
+}
+
+/**
+ * generic_setlease - sets a lease on an open file
+ * @filp: file pointer
+ * @arg: type of lease to obtain
+ * @flp: input - file_lock to use, output - file_lock inserted
+ *
+ * The (input) flp->fl_lmops->lm_break function is required
+ * by break_lease().
+ *
+ * Called with file_lock_lock held.
+ */
+int generic_setlease(struct file *filp, long arg, struct file_lock **flp)
+{
+ struct dentry *dentry = filp->f_path.dentry;
+ struct inode *inode = dentry->d_inode;
+ int error;
+
+ if ((!uid_eq(current_fsuid(), inode->i_uid)) && !capable(CAP_LEASE))
+ return -EACCES;
+ if (!S_ISREG(inode->i_mode))
+ return -EINVAL;
+ error = security_file_lock(filp, arg);
+ if (error)
+ return error;
+
+ time_out_leases(inode);
+
+ BUG_ON(!(*flp)->fl_lmops->lm_break);
+
+ switch (arg) {
+ case F_UNLCK:
+ return generic_delete_lease(filp, flp);
+ case F_RDLCK:
+ case F_WRLCK:
+ return generic_add_lease(filp, arg, flp);
+ default:
+ return -EINVAL;
+ }
+}
EXPORT_SYMBOL(generic_setlease);
static int __vfs_setlease(struct file *filp, long arg, struct file_lock **lease)
* @lease: file_lock to use
*
* Call this to establish a lease on the file.
- * The (*lease)->fl_lmops->fl_break operation must be set; if not,
+ * The (*lease)->fl_lmops->lm_break operation must be set; if not,
* break_lease will oops!
*
* This will call the filesystem's setlease file method, if
*/
SYSCALL_DEFINE2(flock, unsigned int, fd, unsigned int, cmd)
{
- struct file *filp;
+ struct fd f = fdget(fd);
struct file_lock *lock;
int can_sleep, unlock;
int error;
error = -EBADF;
- filp = fget(fd);
- if (!filp)
+ if (!f.file)
goto out;
can_sleep = !(cmd & LOCK_NB);
unlock = (cmd == LOCK_UN);
if (!unlock && !(cmd & LOCK_MAND) &&
- !(filp->f_mode & (FMODE_READ|FMODE_WRITE)))
+ !(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
goto out_putf;
- error = flock_make_lock(filp, &lock, cmd);
+ error = flock_make_lock(f.file, &lock, cmd);
if (error)
goto out_putf;
if (can_sleep)
lock->fl_flags |= FL_SLEEP;
- error = security_file_lock(filp, lock->fl_type);
+ error = security_file_lock(f.file, lock->fl_type);
if (error)
goto out_free;
- if (filp->f_op && filp->f_op->flock)
- error = filp->f_op->flock(filp,
+ if (f.file->f_op && f.file->f_op->flock)
+ error = f.file->f_op->flock(f.file,
(can_sleep) ? F_SETLKW : F_SETLK,
lock);
else
- error = flock_lock_file_wait(filp, lock);
+ error = flock_lock_file_wait(f.file, lock);
out_free:
locks_free_lock(lock);
out_putf:
- fput(filp);
+ fdput(f);
out:
return error;
}
* 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
+ * lm_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,
- * it must return FILE_LOCK_DEFERRED, and call ->fl_grant() when the lock
+ * it must return FILE_LOCK_DEFERRED, and call ->lm_grant() when the lock
* request completes.
* If the request is for non-blocking lock the file system should return
* FILE_LOCK_DEFERRED then try to get the lock and call the callback routine
* 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
- * ->fl_grant() before returning to the caller with a FILE_LOCK_DEFERRED
+ * ->lm_grant() before returning to the caller with a FILE_LOCK_DEFERRED
* return code.
*/
int vfs_lock_file(struct file *filp, unsigned int cmd, struct file_lock *fl, struct file_lock *conf)
if (copy_from_user(&flock, l, sizeof(flock)))
goto out;
- inode = filp->f_path.dentry->d_inode;
+ inode = file_inode(filp);
/* Don't allow mandatory locks on files that may be memory mapped
* and shared.
if (copy_from_user(&flock, l, sizeof(flock)))
goto out;
- inode = filp->f_path.dentry->d_inode;
+ inode = file_inode(filp);
/* Don't allow mandatory locks on files that may be memory mapped
* and shared.
* 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.
*/
- if (!filp->f_path.dentry->d_inode->i_flock)
+ if (!file_inode(filp)->i_flock)
return;
lock.fl_type = F_UNLCK;
*/
void locks_remove_flock(struct file *filp)
{
- struct inode * inode = filp->f_path.dentry->d_inode;
+ struct inode * inode = file_inode(filp);
struct file_lock *fl;
struct file_lock **before;
fl_pid = fl->fl_pid;
if (fl->fl_file != NULL)
- inode = fl->fl_file->f_path.dentry->d_inode;
+ inode = file_inode(fl->fl_file);
seq_printf(f, "%lld:%s ", id, pfx);
if (IS_POSIX(fl)) {
}
} else if (IS_LEASE(fl)) {
seq_printf(f, "LEASE ");
- if (fl->fl_type & F_INPROGRESS)
+ if (lease_breaking(fl))
seq_printf(f, "BREAKING ");
else if (fl->fl_file)
seq_printf(f, "ACTIVE ");
: (fl->fl_type & LOCK_WRITE) ? "WRITE" : "NONE ");
} else {
seq_printf(f, "%s ",
- (fl->fl_type & F_INPROGRESS)
- ? (fl->fl_type & F_UNLCK) ? "UNLCK" : "READ "
- : (fl->fl_type & F_WRLCK) ? "WRITE" : "READ ");
+ (lease_breaking(fl))
+ ? (fl->fl_type == F_UNLCK) ? "UNLCK" : "READ "
+ : (fl->fl_type == F_WRLCK) ? "WRITE" : "READ ");
}
if (inode) {
#ifdef WE_CAN_BREAK_LSLK_NOW
static int __init filelock_init(void)
{
filelock_cache = kmem_cache_create("file_lock_cache",
- sizeof(struct file_lock), 0, SLAB_PANIC,
- init_once);
+ sizeof(struct file_lock), 0, SLAB_PANIC, NULL);
+
return 0;
}