linux/fs/dlm/plock.c
Alexander Aring 7c53e847ff dlm: fix plock lookup when using multiple lockspaces
All posix lock ops, for all lockspaces (gfs2 file systems) are
sent to userspace (dlm_controld) through a single misc device.
The dlm_controld daemon reads the ops from the misc device
and sends them to other cluster nodes using separate, per-lockspace
cluster api communication channels.  The ops for a single lockspace
are ordered at this level, so that the results are received in
the same sequence that the requests were sent.  When the results
are sent back to the kernel via the misc device, they are again
funneled through the single misc device for all lockspaces.  When
the dlm code in the kernel processes the results from the misc
device, these results will be returned in the same sequence that
the requests were sent, on a per-lockspace basis.  A recent change
in this request/reply matching code missed the "per-lockspace"
check (fsid comparison) when matching request and reply, so replies
could be incorrectly matched to requests from other lockspaces.

Cc: stable@vger.kernel.org
Reported-by: Barry Marson <bmarson@redhat.com>
Fixes: 57e2c2f2d9 ("fs: dlm: fix mismatch of plock results from userspace")
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2023-08-25 10:31:39 -05:00

641 lines
14 KiB
C

// 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->fl_pid;
op->info.ex = (fl->fl_type == F_WRLCK);
op->info.wait = IS_SETLKW(cmd);
op->info.fsid = ls->ls_global_id;
op->info.number = number;
op->info.start = fl->fl_start;
op->info.end = fl->fl_end;
/* 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;
}
/* fl_owner is lockd which doesn't distinguish
processes on the nfs client */
op->info.owner = (__u64) fl->fl_pid;
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;
} else {
op->info.owner = (__u64)(long) fl->fl_owner;
}
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->fl_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 fl_flags = fl->fl_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->fl_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->fl_pid;
op->info.fsid = ls->ls_global_id;
op->info.number = number;
op->info.start = fl->fl_start;
op->info.end = fl->fl_end;
if (fl->fl_lmops && fl->fl_lmops->lm_grant)
op->info.owner = (__u64) fl->fl_pid;
else
op->info.owner = (__u64)(long) fl->fl_owner;
if (fl->fl_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->fl_flags = fl_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->fl_pid;
info.ex = (fl->fl_type == F_WRLCK);
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)fl->fl_pid;
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->fl_pid;
op->info.ex = (fl->fl_type == F_WRLCK);
op->info.fsid = ls->ls_global_id;
op->info.number = number;
op->info.start = fl->fl_start;
op->info.end = fl->fl_end;
if (fl->fl_lmops && fl->fl_lmops->lm_grant)
op->info.owner = (__u64) fl->fl_pid;
else
op->info.owner = (__u64)(long) fl->fl_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->fl_type = F_UNLCK;
if (rv == -ENOENT)
rv = 0;
else if (rv > 0) {
locks_init_lock(fl);
fl->fl_type = (op->info.ex) ? F_WRLCK : F_RDLCK;
fl->fl_flags = FL_POSIX;
fl->fl_pid = op->info.pid;
if (op->info.nodeid != dlm_our_nodeid())
fl->fl_pid = -fl->fl_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));
}