514 lines
12 KiB
C
514 lines
12 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2005-2008 Red Hat, Inc. All rights reserved.
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*/
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#include <linux/fs.h>
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#include <linux/filelock.h>
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#include <linux/miscdevice.h>
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#include <linux/poll.h>
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#include <linux/dlm.h>
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#include <linux/dlm_plock.h>
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#include <linux/slab.h>
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#include "dlm_internal.h"
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#include "lockspace.h"
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static DEFINE_SPINLOCK(ops_lock);
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static LIST_HEAD(send_list);
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static LIST_HEAD(recv_list);
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static DECLARE_WAIT_QUEUE_HEAD(send_wq);
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static DECLARE_WAIT_QUEUE_HEAD(recv_wq);
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struct plock_async_data {
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void *fl;
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void *file;
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struct file_lock flc;
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int (*callback)(struct file_lock *fl, int result);
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};
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struct plock_op {
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struct list_head list;
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int done;
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/* if lock op got interrupted while waiting dlm_controld reply */
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bool sigint;
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struct dlm_plock_info info;
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/* if set indicates async handling */
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struct plock_async_data *data;
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};
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static inline void set_version(struct dlm_plock_info *info)
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{
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info->version[0] = DLM_PLOCK_VERSION_MAJOR;
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info->version[1] = DLM_PLOCK_VERSION_MINOR;
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info->version[2] = DLM_PLOCK_VERSION_PATCH;
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}
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static int check_version(struct dlm_plock_info *info)
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{
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if ((DLM_PLOCK_VERSION_MAJOR != info->version[0]) ||
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(DLM_PLOCK_VERSION_MINOR < info->version[1])) {
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log_print("plock device version mismatch: "
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"kernel (%u.%u.%u), user (%u.%u.%u)",
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DLM_PLOCK_VERSION_MAJOR,
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DLM_PLOCK_VERSION_MINOR,
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DLM_PLOCK_VERSION_PATCH,
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info->version[0],
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info->version[1],
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info->version[2]);
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return -EINVAL;
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}
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return 0;
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}
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static void dlm_release_plock_op(struct plock_op *op)
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{
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kfree(op->data);
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kfree(op);
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}
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static void send_op(struct plock_op *op)
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{
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set_version(&op->info);
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spin_lock(&ops_lock);
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list_add_tail(&op->list, &send_list);
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spin_unlock(&ops_lock);
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wake_up(&send_wq);
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}
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/* If a process was killed while waiting for the only plock on a file,
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locks_remove_posix will not see any lock on the file so it won't
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send an unlock-close to us to pass on to userspace to clean up the
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abandoned waiter. So, we have to insert the unlock-close when the
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lock call is interrupted. */
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static void do_unlock_close(const struct dlm_plock_info *info)
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{
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struct plock_op *op;
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op = kzalloc(sizeof(*op), GFP_NOFS);
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if (!op)
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return;
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op->info.optype = DLM_PLOCK_OP_UNLOCK;
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op->info.pid = info->pid;
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op->info.fsid = info->fsid;
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op->info.number = info->number;
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op->info.start = 0;
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op->info.end = OFFSET_MAX;
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op->info.owner = info->owner;
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op->info.flags |= DLM_PLOCK_FL_CLOSE;
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send_op(op);
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}
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int dlm_posix_lock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
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int cmd, struct file_lock *fl)
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{
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struct plock_async_data *op_data;
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struct dlm_ls *ls;
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struct plock_op *op;
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int rv;
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ls = dlm_find_lockspace_local(lockspace);
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if (!ls)
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return -EINVAL;
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op = kzalloc(sizeof(*op), GFP_NOFS);
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if (!op) {
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rv = -ENOMEM;
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goto out;
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}
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op->info.optype = DLM_PLOCK_OP_LOCK;
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op->info.pid = fl->fl_pid;
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op->info.ex = (fl->fl_type == F_WRLCK);
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op->info.wait = IS_SETLKW(cmd);
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op->info.fsid = ls->ls_global_id;
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op->info.number = number;
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op->info.start = fl->fl_start;
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op->info.end = fl->fl_end;
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/* async handling */
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if (fl->fl_lmops && fl->fl_lmops->lm_grant) {
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op_data = kzalloc(sizeof(*op_data), GFP_NOFS);
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if (!op_data) {
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dlm_release_plock_op(op);
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rv = -ENOMEM;
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goto out;
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}
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/* fl_owner is lockd which doesn't distinguish
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processes on the nfs client */
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op->info.owner = (__u64) fl->fl_pid;
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op_data->callback = fl->fl_lmops->lm_grant;
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locks_init_lock(&op_data->flc);
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locks_copy_lock(&op_data->flc, fl);
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op_data->fl = fl;
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op_data->file = file;
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op->data = op_data;
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send_op(op);
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rv = FILE_LOCK_DEFERRED;
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goto out;
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} else {
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op->info.owner = (__u64)(long) fl->fl_owner;
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}
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send_op(op);
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rv = wait_event_interruptible(recv_wq, (op->done != 0));
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if (rv == -ERESTARTSYS) {
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spin_lock(&ops_lock);
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/* recheck under ops_lock if we got a done != 0,
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* if so this interrupt case should be ignored
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*/
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if (op->done != 0) {
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spin_unlock(&ops_lock);
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goto do_lock_wait;
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}
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op->sigint = true;
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spin_unlock(&ops_lock);
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log_debug(ls, "%s: wait interrupted %x %llx pid %d",
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__func__, ls->ls_global_id,
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(unsigned long long)number, op->info.pid);
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goto out;
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}
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do_lock_wait:
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WARN_ON(!list_empty(&op->list));
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rv = op->info.rv;
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if (!rv) {
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if (locks_lock_file_wait(file, fl) < 0)
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log_error(ls, "dlm_posix_lock: vfs lock error %llx",
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(unsigned long long)number);
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}
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dlm_release_plock_op(op);
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out:
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dlm_put_lockspace(ls);
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return rv;
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}
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EXPORT_SYMBOL_GPL(dlm_posix_lock);
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/* Returns failure iff a successful lock operation should be canceled */
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static int dlm_plock_callback(struct plock_op *op)
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{
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struct plock_async_data *op_data = op->data;
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struct file *file;
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struct file_lock *fl;
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struct file_lock *flc;
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int (*notify)(struct file_lock *fl, int result) = NULL;
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int rv = 0;
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WARN_ON(!list_empty(&op->list));
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/* check if the following 2 are still valid or make a copy */
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file = op_data->file;
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flc = &op_data->flc;
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fl = op_data->fl;
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notify = op_data->callback;
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if (op->info.rv) {
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notify(fl, op->info.rv);
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goto out;
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}
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/* got fs lock; bookkeep locally as well: */
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flc->fl_flags &= ~FL_SLEEP;
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if (posix_lock_file(file, flc, NULL)) {
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/*
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* This can only happen in the case of kmalloc() failure.
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* The filesystem's own lock is the authoritative lock,
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* so a failure to get the lock locally is not a disaster.
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* As long as the fs cannot reliably cancel locks (especially
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* in a low-memory situation), we're better off ignoring
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* this failure than trying to recover.
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*/
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log_print("dlm_plock_callback: vfs lock error %llx file %p fl %p",
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(unsigned long long)op->info.number, file, fl);
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}
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rv = notify(fl, 0);
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if (rv) {
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/* XXX: We need to cancel the fs lock here: */
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log_print("dlm_plock_callback: lock granted after lock request "
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"failed; dangling lock!\n");
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goto out;
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}
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out:
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dlm_release_plock_op(op);
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return rv;
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}
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int dlm_posix_unlock(dlm_lockspace_t *lockspace, u64 number, struct file *file,
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struct file_lock *fl)
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{
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struct dlm_ls *ls;
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struct plock_op *op;
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int rv;
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unsigned char fl_flags = fl->fl_flags;
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ls = dlm_find_lockspace_local(lockspace);
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if (!ls)
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return -EINVAL;
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op = kzalloc(sizeof(*op), GFP_NOFS);
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if (!op) {
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rv = -ENOMEM;
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goto out;
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}
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/* cause the vfs unlock to return ENOENT if lock is not found */
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fl->fl_flags |= FL_EXISTS;
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rv = locks_lock_file_wait(file, fl);
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if (rv == -ENOENT) {
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rv = 0;
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goto out_free;
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}
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if (rv < 0) {
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log_error(ls, "dlm_posix_unlock: vfs unlock error %d %llx",
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rv, (unsigned long long)number);
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}
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op->info.optype = DLM_PLOCK_OP_UNLOCK;
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op->info.pid = fl->fl_pid;
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op->info.fsid = ls->ls_global_id;
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op->info.number = number;
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op->info.start = fl->fl_start;
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op->info.end = fl->fl_end;
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if (fl->fl_lmops && fl->fl_lmops->lm_grant)
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op->info.owner = (__u64) fl->fl_pid;
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else
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op->info.owner = (__u64)(long) fl->fl_owner;
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if (fl->fl_flags & FL_CLOSE) {
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op->info.flags |= DLM_PLOCK_FL_CLOSE;
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send_op(op);
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rv = 0;
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goto out;
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}
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send_op(op);
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wait_event(recv_wq, (op->done != 0));
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WARN_ON(!list_empty(&op->list));
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rv = op->info.rv;
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if (rv == -ENOENT)
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rv = 0;
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out_free:
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dlm_release_plock_op(op);
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out:
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dlm_put_lockspace(ls);
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fl->fl_flags = fl_flags;
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return rv;
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}
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EXPORT_SYMBOL_GPL(dlm_posix_unlock);
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int dlm_posix_get(dlm_lockspace_t *lockspace, u64 number, struct file *file,
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struct file_lock *fl)
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{
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struct dlm_ls *ls;
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struct plock_op *op;
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int rv;
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ls = dlm_find_lockspace_local(lockspace);
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if (!ls)
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return -EINVAL;
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op = kzalloc(sizeof(*op), GFP_NOFS);
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if (!op) {
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rv = -ENOMEM;
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goto out;
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}
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op->info.optype = DLM_PLOCK_OP_GET;
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op->info.pid = fl->fl_pid;
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op->info.ex = (fl->fl_type == F_WRLCK);
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op->info.fsid = ls->ls_global_id;
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op->info.number = number;
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op->info.start = fl->fl_start;
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op->info.end = fl->fl_end;
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if (fl->fl_lmops && fl->fl_lmops->lm_grant)
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op->info.owner = (__u64) fl->fl_pid;
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else
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op->info.owner = (__u64)(long) fl->fl_owner;
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send_op(op);
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wait_event(recv_wq, (op->done != 0));
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WARN_ON(!list_empty(&op->list));
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/* info.rv from userspace is 1 for conflict, 0 for no-conflict,
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-ENOENT if there are no locks on the file */
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rv = op->info.rv;
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fl->fl_type = F_UNLCK;
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if (rv == -ENOENT)
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rv = 0;
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else if (rv > 0) {
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locks_init_lock(fl);
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fl->fl_type = (op->info.ex) ? F_WRLCK : F_RDLCK;
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fl->fl_flags = FL_POSIX;
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fl->fl_pid = -op->info.pid;
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fl->fl_start = op->info.start;
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fl->fl_end = op->info.end;
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rv = 0;
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}
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dlm_release_plock_op(op);
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out:
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dlm_put_lockspace(ls);
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return rv;
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}
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EXPORT_SYMBOL_GPL(dlm_posix_get);
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/* a read copies out one plock request from the send list */
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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(&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)
|
||
|
|
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;
|
||
|
|
|
||
|
|
if (check_version(&info))
|
||
|
|
return -EINVAL;
|
||
|
|
|
||
|
|
spin_lock(&ops_lock);
|
||
|
|
list_for_each_entry(iter, &recv_list, list) {
|
||
|
|
if (iter->info.fsid == info.fsid &&
|
||
|
|
iter->info.number == info.number &&
|
||
|
|
iter->info.owner == info.owner) {
|
||
|
|
if (iter->sigint) {
|
||
|
|
list_del(&iter->list);
|
||
|
|
spin_unlock(&ops_lock);
|
||
|
|
|
||
|
|
pr_debug("%s: sigint cleanup %x %llx pid %d",
|
||
|
|
__func__, iter->info.fsid,
|
||
|
|
(unsigned long long)iter->info.number,
|
||
|
|
iter->info.pid);
|
||
|
|
do_unlock_close(&iter->info);
|
||
|
|
memcpy(&iter->info, &info, sizeof(info));
|
||
|
|
dlm_release_plock_op(iter);
|
||
|
|
return count;
|
||
|
|
}
|
||
|
|
list_del_init(&iter->list);
|
||
|
|
memcpy(&iter->info, &info, sizeof(info));
|
||
|
|
if (iter->data)
|
||
|
|
do_callback = 1;
|
||
|
|
else
|
||
|
|
iter->done = 1;
|
||
|
|
op = iter;
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
spin_unlock(&ops_lock);
|
||
|
|
|
||
|
|
if (op) {
|
||
|
|
if (do_callback)
|
||
|
|
dlm_plock_callback(op);
|
||
|
|
else
|
||
|
|
wake_up(&recv_wq);
|
||
|
|
} else
|
||
|
|
log_print("%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);
|
||
|
|
}
|
||
|
|
|