// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2005-2008 Red Hat, Inc. All rights reserved.
*/
#include <linux/fs.h>
#include <linux/filelock.h>
#include <linux/miscdevice.h>
#include <linux/poll.h>
#include <linux/dlm.h>
#include <linux/dlm_plock.h>
#include <linux/slab.h>
#include <trace/events/dlm.h>
#include "dlm_internal.h"
#include "lockspace.h"
static DEFINE_SPINLOCK(ops_lock);
static LIST_HEAD(send_list);
static LIST_HEAD(recv_list);
static DECLARE_WAIT_QUEUE_HEAD(send_wq);
static DECLARE_WAIT_QUEUE_HEAD(recv_wq);
struct plock_async_data {
void *fl;
void *file;
struct file_lock flc;
int (*callback)(struct file_lock *fl, int result);
};
struct plock_op {
struct list_head list;
int done;
struct dlm_plock_info info;
/* if set indicates async handling */
struct plock_async_data *data;
};
static inline void set_version(struct dlm_plock_info *info)
{
info->version[0] = DLM_PLOCK_VERSION_MAJOR;
info->version[1] = DLM_PLOCK_VERSION_MINOR;
info->version[2] = DLM_PLOCK_VERSION_PATCH;
}
static struct plock_op *plock_lookup_waiter(const struct dlm_plock_info *info)
{
struct plock_op *op = NULL, *iter;
list_for_each_entry(iter, &recv_list, list) {
if (iter->info.fsid == info->fsid &&
iter->info.number == info->number &&
iter->info.owner == info->owner &&
iter->info.pid == info->pid &&
iter->info.start == info->start &&
iter->info.end == info->end &&
iter->info.ex == info->ex &&
iter->info.wait) {
op = iter;
break;
}
}
return op;
}
static int check_version(struct dlm_plock_info *info)
{
if ((DLM_PLOCK_VERSION_MAJOR != info->version[0]) ||
(DLM_PLOCK_VERSION_MINOR < info->version[1])) {
log_print("plock device version mismatch: "
"kernel (%u.%u.%u), user (%u.%u.%u)",
DLM_PLOCK_VERSION_MAJOR,
DLM_PLOCK_VERSION_MINOR,
DLM_PLOCK_VERSION_PATCH,
info->version[0],
info->version[1],
info->version[2]);
return -EINVAL;
}
return 0;
}
static void dlm_release_plock_op(struct plock_op *op)
{
kfree(op->data);
kfree(op);
}
static void send_op(struct plock_op *op)
{
set_version(&op->info);
spin_lock(&ops_lock);
list_add_tail(&op->list, &send_list);
spin_unlock(&ops_lock);
wake_up(&send_wq);
}
static int do_lock_cancel(const struct dlm_plock_info *orig_info)
{
struct plock_op *op;
int rv;
op = kzalloc(sizeof(*op), GFP_NOFS);
if (!op)
return -ENOMEM;
op->info = *orig_info;
op->info.optype = DLM_PLOCK_OP_CANCEL;
op->info.wait = 0;
send_op(op);
wait_event(recv_wq, (op->done != 0));
rv = op->info.rv;
dlm_release_plock_op(op);
return rv;
}
int dlm_posix_lock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
int cmd, struct file_lock *fl)
{
struct plock_async_data *op_data;
struct dlm_ls *ls;
struct plock_op *op;
int rv;
ls = dlm_find_lockspace_local(lockspace);
if (!ls)
return -EINVAL;
op = kzalloc(sizeof(*op), GFP_NOFS);
if (!op) {
rv = -ENOMEM;
goto out;
}
op->info.optype = DLM_PLOCK_OP_LOCK;
op->info.pid = fl->c.flc_pid;
op->info.ex = lock_is_write(fl);
op->info.wait = !!(fl->c.flc_flags & FL_SLEEP);
op->info.fsid = ls->ls_global_id;
op->info.number = number;
op->info.start = fl->fl_start;
op->info.end = fl->fl_end;
op->info.owner = (__u64)(long) fl->c.flc_owner;
/* async handling */
if (fl->fl_lmops && fl->fl_lmops->lm_grant) {
op_data = kzalloc(sizeof(*op_data), GFP_NOFS);
if (!op_data) {
dlm_release_plock_op(op);
rv = -ENOMEM;
goto out;
}
op_data->callback = fl->fl_lmops->lm_grant;
locks_init_lock(&op_data->flc);
locks_copy_lock(&op_data->flc, fl);
op_data->fl = fl;
op_data->file = file;
op->data = op_data;
send_op(op);
rv = FILE_LOCK_DEFERRED;
goto out;
}
send_op(op);
if (op->info.wait) {
rv = wait_event_interruptible(recv_wq, (op->done != 0));
if (rv == -ERESTARTSYS) {
spin_lock(&ops_lock);
/* recheck under ops_lock if we got a done != 0,
* if so this interrupt case should be ignored
*/
if (op->done != 0) {
spin_unlock(&ops_lock);
goto do_lock_wait;
}
spin_unlock(&ops_lock);
rv = do_lock_cancel(&op->info);
switch (rv) {
case 0:
/* waiter was deleted in user space, answer will never come
* remove original request. The original request must be
* on recv_list because the answer of do_lock_cancel()
* synchronized it.
*/
spin_lock(&ops_lock);
list_del(&op->list);
spin_unlock(&ops_lock);
rv = -EINTR;
break;
case -ENOENT:
/* cancellation wasn't successful but op should be done */
fallthrough;
default:
/* internal error doing cancel we need to wait */
goto wait;
}
log_debug(ls, "%s: wait interrupted %x %llx pid %d",
__func__, ls->ls_global_id,
(unsigned long long)number, op->info.pid);
dlm_release_plock_op(op);
goto out;
}
} else {
wait:
wait_event(recv_wq, (op->done != 0));
}
do_lock_wait:
WARN_ON(!list_empty(&op->list));
rv = op->info.rv;
if (!rv) {
if (locks_lock_file_wait(file, fl) < 0)
log_error(ls, "dlm_posix_lock: vfs lock error %llx",
(unsigned long long)number);
}
dlm_release_plock_op(op);
out:
dlm_put_lockspace(ls);
return rv;
}
EXPORT_SYMBOL_GPL(dlm_posix_lock);
/* Returns failure iff a successful lock operation should be canceled */
static int dlm_plock_callback(struct plock_op *op)
{
struct plock_async_data *op_data = op->data;
struct file *file;
struct file_lock *fl;
struct file_lock *flc;
int (*notify)(struct file_lock *fl, int result) = NULL;
int rv = 0;
WARN_ON(!list_empty(&op->list));
/* check if the following 2 are still valid or make a copy */
file = op_data->file;
flc = &op_data->flc;
fl = op_data->fl;
notify = op_data->callback;
if (op->info.rv) {
notify(fl, op->info.rv);
goto out;
}
/* got fs lock; bookkeep locally as well: */
flc->c.flc_flags &= ~FL_SLEEP;
if (posix_lock_file(file, flc, NULL)) {
/*
* This can only happen in the case of kmalloc() failure.
* The filesystem's own lock is the authoritative lock,
* so a failure to get the lock locally is not a disaster.
* As long as the fs cannot reliably cancel locks (especially
* in a low-memory situation), we're better off ignoring
* this failure than trying to recover.
*/
log_print("dlm_plock_callback: vfs lock error %llx file %p fl %p",
(unsigned long long)op->info.number, file, fl);
}
rv = notify(fl, 0);
if (rv) {
/* XXX: We need to cancel the fs lock here: */
log_print("%s: lock granted after lock request failed; dangling lock!",
__func__);
goto out;
}
out:
dlm_release_plock_op(op);
return rv;
}
int dlm_posix_unlock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
struct file_lock *fl)
{
struct dlm_ls *ls;
struct plock_op *op;
int rv;
unsigned char saved_flags = fl->c.flc_flags;
ls = dlm_find_lockspace_local(lockspace);
if (!ls)
return -EINVAL;
op = kzalloc(sizeof(*op), GFP_NOFS);
if (!op) {
rv = -ENOMEM;
goto out;
}
/* cause the vfs unlock to return ENOENT if lock is not found */
fl->c.flc_flags |= FL_EXISTS;
rv = locks_lock_file_wait(file, fl);
if (rv == -ENOENT) {
rv = 0;
goto out_free;
}
if (rv < 0) {
log_error(ls, "dlm_posix_unlock: vfs unlock error %d %llx",
rv, (unsigned long long)number);
}
op->info.optype = DLM_PLOCK_OP_UNLOCK;
op->info.pid = fl->c.flc_pid;
op->info.fsid = ls->ls_global_id;
op->info.number = number;
op->info.start = fl->fl_start;
op->info.end = fl->fl_end;
op->info.owner = (__u64)(long) fl->c.flc_owner;
if (fl->c.flc_flags & FL_CLOSE) {
op->info.flags |= DLM_PLOCK_FL_CLOSE;
send_op(op);
rv = 0;
goto out;
}
send_op(op);
wait_event(recv_wq, (op->done != 0));
WARN_ON(!list_empty(&op->list));
rv = op->info.rv;
if (rv == -ENOENT)
rv = 0;
out_free:
dlm_release_plock_op(op);
out:
dlm_put_lockspace(ls);
fl->c.flc_flags = saved_flags;
return rv;
}
EXPORT_SYMBOL_GPL(dlm_posix_unlock);
/*
* NOTE: This implementation can only handle async lock requests as nfs
* do it. It cannot handle cancellation of a pending lock request sitting
* in wait_event(), but for now only nfs is the only user local kernel
* user.
*/
int dlm_posix_cancel(dlm_lockspace_t *lockspace, u64 number, struct file *file,
struct file_lock *fl)
{
struct dlm_plock_info info;
struct plock_op *op;
struct dlm_ls *ls;
int rv;
/* this only works for async request for now and nfs is the only
* kernel user right now.
*/
if (WARN_ON_ONCE(!fl->fl_lmops || !fl->fl_lmops->lm_grant))
return -EOPNOTSUPP;
ls = dlm_find_lockspace_local(lockspace);
if (!ls)
return -EINVAL;
memset(&info, 0, sizeof(info));
info.pid = fl->c.flc_pid;
info.ex = lock_is_write(fl);
info.fsid = ls->ls_global_id;
dlm_put_lockspace(ls);
info.number = number;
info.start = fl->fl_start;
info.end = fl->fl_end;
info.owner = (__u64)(long) fl->c.flc_owner;
rv = do_lock_cancel(&info);
switch (rv) {
case 0:
spin_lock(&ops_lock);
/* lock request to cancel must be on recv_list because
* do_lock_cancel() synchronizes it.
*/
op = plock_lookup_waiter(&info);
if (WARN_ON_ONCE(!op)) {
spin_unlock(&ops_lock);
rv = -ENOLCK;
break;
}
list_del(&op->list);
spin_unlock(&ops_lock);
WARN_ON(op->info.optype != DLM_PLOCK_OP_LOCK);
op->data->callback(op->data->fl, -EINTR);
dlm_release_plock_op(op);
rv = -EINTR;
break;
case -ENOENT:
/* if cancel wasn't successful we probably were to late
* or it was a non-blocking lock request, so just unlock it.
*/
rv = dlm_posix_unlock(lockspace, number, file, fl);
break;
default:
break;
}
return rv;
}
EXPORT_SYMBOL_GPL(dlm_posix_cancel);
int dlm_posix_get(dlm_lockspace_t *lockspace, u64 number, struct file *file,
struct file_lock *fl)
{
struct dlm_ls *ls;
struct plock_op *op;
int rv;
ls = dlm_find_lockspace_local(lockspace);
if (!ls)
return -EINVAL;
op = kzalloc(sizeof(*op), GFP_NOFS);
if (!op) {
rv = -ENOMEM;
goto out;
}
op->info.optype = DLM_PLOCK_OP_GET;
op->info.pid = fl->c.flc_pid;
op->info.ex = lock_is_write(fl);
op->info.fsid = ls->ls_global_id;
op->info.number = number;
op->info.start = fl->fl_start;
op->info.end = fl->fl_end;
op->info.owner = (__u64)(long) fl->c.flc_owner;
send_op(op);
wait_event(recv_wq, (op->done != 0));
WARN_ON(!list_empty(&op->list));
/* info.rv from userspace is 1 for conflict, 0 for no-conflict,
-ENOENT if there are no locks on the file */
rv = op->info.rv;
fl->c.flc_type = F_UNLCK;
if (rv == -ENOENT)
rv = 0;
else if (rv > 0) {
locks_init_lock(fl);
fl->c.flc_type = (op->info.ex) ? F_WRLCK : F_RDLCK;
fl->c.flc_flags = FL_POSIX;
fl->c.flc_pid = op->info.pid;
if (op->info.nodeid != dlm_our_nodeid())
fl->c.flc_pid = -fl->c.flc_pid;
fl->fl_start = op->info.start;
fl->fl_end = op->info.end;
rv = 0;
}
dlm_release_plock_op(op);
out:
dlm_put_lockspace(ls);
return rv;
}
EXPORT_SYMBOL_GPL(dlm_posix_get);
/* a read copies out one plock request from the send list */
static ssize_t dev_read(struct file *file, char __user *u, size_t count,
loff_t *ppos)
{
struct dlm_plock_info info;
struct plock_op *op = NULL;
if (count < sizeof(info))
return -EINVAL;
spin_lock(&ops_lock);
if (!list_empty(&send_list)) {
op = list_first_entry(&send_list, struct plock_op, list);
if (op->info.flags & DLM_PLOCK_FL_CLOSE)
list_del(&op->list);
else
list_move_tail(&op->list, &recv_list);
memcpy(&info, &op->info, sizeof(info));
}
spin_unlock(&ops_lock);
if (!op)
return -EAGAIN;
trace_dlm_plock_read(&info);
/* there is no need to get a reply from userspace for unlocks
that were generated by the vfs cleaning up for a close
(the process did not make an unlock call). */
if (op->info.flags & DLM_PLOCK_FL_CLOSE)
dlm_release_plock_op(op);
if (copy_to_user(u, &info, sizeof(info)))
return -EFAULT;
return sizeof(info);
}
/* a write copies in one plock result that should match a plock_op
on the recv list */
static ssize_t dev_write(struct file *file, const char __user *u, size_t count,
loff_t *ppos)
{
struct plock_op *op = NULL, *iter;
struct dlm_plock_info info;
int do_callback = 0;
if (count != sizeof(info))
return -EINVAL;
if (copy_from_user(&info, u, sizeof(info)))
return -EFAULT;
trace_dlm_plock_write(&info);
if (check_version(&info))
return -EINVAL;
/*
* The results for waiting ops (SETLKW) can be returned in any
* order, so match all fields to find the op. The results for
* non-waiting ops are returned in the order that they were sent
* to userspace, so match the result with the first non-waiting op.
*/
spin_lock(&ops_lock);
if (info.wait) {
op = plock_lookup_waiter(&info);
} else {
list_for_each_entry(iter, &recv_list, list) {
if (!iter->info.wait &&
iter->info.fsid == info.fsid) {
op = iter;
break;
}
}
}
if (op) {
/* Sanity check that op and info match. */
if (info.wait)
WARN_ON(op->info.optype != DLM_PLOCK_OP_LOCK);
else
WARN_ON(op->info.number != info.number ||
op->info.owner != info.owner ||
op->info.optype != info.optype);
list_del_init(&op->list);
memcpy(&op->info, &info, sizeof(info));
if (op->data)
do_callback = 1;
else
op->done = 1;
}
spin_unlock(&ops_lock);
if (op) {
if (do_callback)
dlm_plock_callback(op);
else
wake_up(&recv_wq);
} else
pr_debug("%s: no op %x %llx", __func__,
info.fsid, (unsigned long long)info.number);
return count;
}
static __poll_t dev_poll(struct file *file, poll_table *wait)
{
__poll_t mask = 0;
poll_wait(file, &send_wq, wait);
spin_lock(&ops_lock);
if (!list_empty(&send_list))
mask = EPOLLIN | EPOLLRDNORM;
spin_unlock(&ops_lock);
return mask;
}
static const struct file_operations dev_fops = {
.read = dev_read,
.write = dev_write,
.poll = dev_poll,
.owner = THIS_MODULE,
.llseek = noop_llseek,
};
static struct miscdevice plock_dev_misc = {
.minor = MISC_DYNAMIC_MINOR,
.name = DLM_PLOCK_MISC_NAME,
.fops = &dev_fops
};
int dlm_plock_init(void)
{
int rv;
rv = misc_register(&plock_dev_misc);
if (rv)
log_print("dlm_plock_init: misc_register failed %d", rv);
return rv;
}
void dlm_plock_exit(void)
{
misc_deregister(&plock_dev_misc);
WARN_ON(!list_empty(&send_list));
WARN_ON(!list_empty(&recv_list));
}
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