- 根目录:
- fs
- dlm
- plock.c
/*
* Copyright (C) 2005-2008 Red Hat, Inc. All rights reserved.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU General Public License version 2.
*/
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/poll.h>
#include <linux/dlm.h>
#include <linux/dlm_plock.h>
#include <linux/slab.h>
#include "dlm_internal.h"
#include "lockspace.h"
static spinlock_t ops_lock;
static struct list_head send_list;
static struct list_head recv_list;
static wait_queue_head_t send_wq;
static wait_queue_head_t recv_wq;
struct plock_op {
struct list_head list;
int done;
struct dlm_plock_info info;
};
struct plock_xop {
struct plock_op xop;
void *callback;
void *fl;
void *file;
struct file_lock flc;
};
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 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 send_op(struct plock_op *op)
{
set_version(&op->info);
INIT_LIST_HEAD(&op->list);
spin_lock(&ops_lock);
list_add_tail(&op->list, &send_list);
spin_unlock(&ops_lock);
wake_up(&send_wq);
}
/* If a process was killed while waiting for the only plock on a file,
locks_remove_posix will not see any lock on the file so it won't
send an unlock-close to us to pass on to userspace to clean up the
abandoned waiter. So, we have to insert the unlock-close when the
lock call is interrupted. */
static void do_unlock_close(struct dlm_ls *ls, u64 number,
struct file *file, struct file_lock *fl)
{
struct plock_op *op;
op = kzalloc(sizeof(*op), GFP_NOFS);
if (!op)
return;
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 = 0;
op->info.end = OFFSET_MAX;
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;
op->info.flags |= DLM_PLOCK_FL_CLOSE;
send_op(op);
}
int dlm_posix_lock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
int cmd, struct file_lock *fl)
{
struct dlm_ls *ls;
struct plock_op *op;
struct plock_xop *xop;
int rv;
ls = dlm_find_lockspace_local(lockspace);
if (!ls)
return -EINVAL;
xop = kzalloc(sizeof(*xop), GFP_NOFS);
if (!xop) {
rv = -ENOMEM;
goto out;
}
op = &xop->xop;
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;
if (fl->fl_lmops && fl->fl_lmops->lm_grant) {
/* fl_owner is lockd which doesn't distinguish
processes on the nfs client */
op->info.owner = (__u64) fl->fl_pid;
xop->callback = fl->fl_lmops->lm_grant;
locks_init_lock(&xop->flc);
locks_copy_lock(&xop->flc, fl);
xop->fl = fl;
xop->file = file;
} else {
op->info.owner = (__u64)(long) fl->fl_owner;
xop->callback = NULL;
}
send_op(op);
if (xop->callback == NULL) {
rv = wait_event_killable(recv_wq, (op->done != 0));
if (rv == -ERESTARTSYS) {
log_debug(ls, "dlm_posix_lock: wait killed %llx",
(unsigned long long)number);
spin_lock(&ops_lock);
list_del(&op->list);
spin_unlock(&ops_lock);
kfree(xop);
do_unlock_close(ls, number, file, fl);
goto out;
}
} else {
rv = FILE_LOCK_DEFERRED;
goto out;
}
spin_lock(&ops_lock);
if (!list_empty(&op->list)) {
log_error(ls, "dlm_posix_lock: op on list %llx",
(unsigned long long)number);
list_del(&op->list);
}
spin_unlock(&ops_lock);
rv = op->info.rv;
if (!rv) {
if (posix_lock_file_wait(file, fl) < 0)
log_error(ls, "dlm_posix_lock: vfs lock error %llx",
(unsigned long long)number);
}
kfree(xop);
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 file *file;
struct file_lock *fl;
struct file_lock *flc;
int (*notify)(void *, void *, int) = NULL;
struct plock_xop *xop = (struct plock_xop *)op;
int rv = 0;
spin_lock(&ops_lock);
if (!list_empty(&op->list)) {
log_print("dlm_plock_callback: op on list %llx",
(unsigned long long)op->info.number);
list_del(&op->list);
}
spin_unlock(&ops_lock);
/* check if the following 2 are still valid or make a copy */
file = xop->file;
flc = &xop->flc;
fl = xop->fl;
notify = xop->callback;
if (op->info.rv) {
notify(fl, NULL, 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, NULL, 0);
if (rv) {
/* XXX: We need to cancel the fs lock here: */
log_print("dlm_plock_callback: lock granted after lock request "
"failed; dangling lock!\n");
goto out;
}
out:
kfree(xop);
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 = posix_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));
spin_lock(&ops_lock);
if (!list_empty(&op->list)) {
log_error(ls, "dlm_posix_unlock: op on list %llx",
(unsigned long long)number);
list_del(&op->list);
}
spin_unlock(&ops_lock);
rv = op->info.rv;
if (rv == -ENOENT)
rv = 0;
out_free:
kfree(op);
out:
dlm_put_lockspace(ls);
fl->fl_flags = fl_flags;
return rv;
}
EXPORT_SYMBOL_GPL(dlm_posix_unlock);
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));
spin_lock(&ops_lock);
if (!list_empty(&op->list)) {
log_error(ls, "dlm_posix_get: op on list %llx",
(unsigned long long)number);
list_del(&op->list);
}
spin_unlock(&ops_lock);
/* 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;
fl->fl_start = op->info.start;
fl->fl_end = op->info.end;
rv = 0;
}
kfree(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_entry(send_list.next, struct plock_op, list);
if (op->info.flags & DLM_PLOCK_FL_CLOSE)
list_del(&op->list);
else
list_move(&op->list, &recv_list);
memcpy(&info, &op->info, sizeof(info));
}
spin_unlock(&ops_lock);
if (!op)
return -EAGAIN;
/* 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)
kfree(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 dlm_plock_info info;
struct plock_op *op;
int found = 0, do_callback = 0;
if (count != sizeof(info))
return -EINVAL;
if (copy_from_user(&info, u, sizeof(info)))
return -EFAULT;
if (check_version(&info))
return -EINVAL;
spin_lock(&ops_lock);
list_for_each_entry(op, &recv_list, list) {
if (op->info.fsid == info.fsid &&
op->info.number == info.number &&
op->info.owner == info.owner) {
struct plock_xop *xop = (struct plock_xop *)op;
list_del_init(&op->list);
memcpy(&op->info, &info, sizeof(info));
if (xop->callback)
do_callback = 1;
else
op->done = 1;
found = 1;
break;
}
}
spin_unlock(&ops_lock);
if (found) {
if (do_callback)
dlm_plock_callback(op);
else
wake_up(&recv_wq);
} else
log_print("dev_write no op %x %llx", info.fsid,
(unsigned long long)info.number);
return count;
}
static unsigned int dev_poll(struct file *file, poll_table *wait)
{
unsigned int mask = 0;
poll_wait(file, &send_wq, wait);
spin_lock(&ops_lock);
if (!list_empty(&send_list))
mask = POLLIN | POLLRDNORM;
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;
spin_lock_init(&ops_lock);
INIT_LIST_HEAD(&send_list);
INIT_LIST_HEAD(&recv_list);
init_waitqueue_head(&send_wq);
init_waitqueue_head(&recv_wq);
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)
{
if (misc_deregister(&plock_dev_misc) < 0)
log_print("dlm_plock_exit: misc_deregister failed");
}