901025d2f3
Allow processes blocked on plock requests to be interrupted when they are killed. This leaves the problem of cleaning up the lock state in userspace. This has three parts: 1. Add a flag to unlock operations sent to userspace indicating the file is being closed. Userspace will then look for and clear any waiting plock operations that were abandoned by an interrupted process. 2. Queue an unlock-close operation (like in 1) to clean up userspace from an interrupted plock request. This is needed because the vfs will not send a cleanup-unlock if it sees no locks on the file, which it won't if the interrupted operation was the only one. 3. Do not use replies from userspace for unlock-close operations because they are unnecessary (they are just cleaning up for the process which did not make an unlock call). This also simplifies the new unlock-close generated from point 2. Signed-off-by: David Teigland <teigland@redhat.com>
504 lines
11 KiB
C
504 lines
11 KiB
C
/*
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* Copyright (C) 2005-2008 Red Hat, Inc. All rights reserved.
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*
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* This copyrighted material is made available to anyone wishing to use,
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* modify, copy, or redistribute it subject to the terms and conditions
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* of the GNU General Public License version 2.
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*/
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#include <linux/fs.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 spinlock_t ops_lock;
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static struct list_head send_list;
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static struct list_head recv_list;
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static wait_queue_head_t send_wq;
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static wait_queue_head_t recv_wq;
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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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struct dlm_plock_info info;
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};
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struct plock_xop {
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struct plock_op xop;
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void *callback;
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void *fl;
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void *file;
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struct file_lock flc;
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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 send_op(struct plock_op *op)
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{
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set_version(&op->info);
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INIT_LIST_HEAD(&op->list);
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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(struct dlm_ls *ls, u64 number,
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struct file *file, struct file_lock *fl)
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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 = 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 = 0;
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op->info.end = OFFSET_MAX;
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if (fl->fl_lmops && fl->fl_lmops->fl_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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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 dlm_ls *ls;
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struct plock_op *op;
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struct plock_xop *xop;
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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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xop = kzalloc(sizeof(*xop), GFP_NOFS);
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if (!xop) {
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rv = -ENOMEM;
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goto out;
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}
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op = &xop->xop;
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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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if (fl->fl_lmops && fl->fl_lmops->fl_grant) {
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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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xop->callback = fl->fl_lmops->fl_grant;
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locks_init_lock(&xop->flc);
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locks_copy_lock(&xop->flc, fl);
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xop->fl = fl;
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xop->file = file;
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} else {
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op->info.owner = (__u64)(long) fl->fl_owner;
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xop->callback = NULL;
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}
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send_op(op);
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if (xop->callback == NULL) {
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rv = wait_event_killable(recv_wq, (op->done != 0));
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if (rv == -ERESTARTSYS) {
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log_debug(ls, "dlm_posix_lock: wait killed %llx",
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(unsigned long long)number);
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spin_lock(&ops_lock);
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list_del(&op->list);
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spin_unlock(&ops_lock);
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kfree(xop);
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do_unlock_close(ls, number, file, fl);
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goto out;
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}
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} else {
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rv = FILE_LOCK_DEFERRED;
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goto out;
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}
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spin_lock(&ops_lock);
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if (!list_empty(&op->list)) {
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log_error(ls, "dlm_posix_lock: op on list %llx",
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(unsigned long long)number);
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list_del(&op->list);
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}
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spin_unlock(&ops_lock);
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rv = op->info.rv;
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if (!rv) {
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if (posix_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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kfree(xop);
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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 file *file;
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struct file_lock *fl;
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struct file_lock *flc;
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int (*notify)(void *, void *, int) = NULL;
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struct plock_xop *xop = (struct plock_xop *)op;
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int rv = 0;
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spin_lock(&ops_lock);
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if (!list_empty(&op->list)) {
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log_print("dlm_plock_callback: op on list %llx",
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(unsigned long long)op->info.number);
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list_del(&op->list);
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}
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spin_unlock(&ops_lock);
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/* check if the following 2 are still valid or make a copy */
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file = xop->file;
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flc = &xop->flc;
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fl = xop->fl;
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notify = xop->callback;
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if (op->info.rv) {
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notify(fl, NULL, 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, NULL, 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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kfree(xop);
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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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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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if (posix_lock_file_wait(file, fl) < 0)
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log_error(ls, "dlm_posix_unlock: vfs unlock error %llx",
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(unsigned long long)number);
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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->fl_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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spin_lock(&ops_lock);
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if (!list_empty(&op->list)) {
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log_error(ls, "dlm_posix_unlock: op on list %llx",
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(unsigned long long)number);
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list_del(&op->list);
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}
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spin_unlock(&ops_lock);
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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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kfree(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_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->fl_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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spin_lock(&ops_lock);
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if (!list_empty(&op->list)) {
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log_error(ls, "dlm_posix_get: op on list %llx",
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(unsigned long long)number);
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list_del(&op->list);
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}
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spin_unlock(&ops_lock);
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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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kfree(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,
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loff_t *ppos)
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{
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struct dlm_plock_info info;
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struct plock_op *op = NULL;
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if (count < sizeof(info))
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return -EINVAL;
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spin_lock(&ops_lock);
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if (!list_empty(&send_list)) {
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op = list_entry(send_list.next, struct plock_op, list);
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if (op->info.flags & DLM_PLOCK_FL_CLOSE)
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list_del(&op->list);
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else
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list_move(&op->list, &recv_list);
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memcpy(&info, &op->info, sizeof(info));
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}
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spin_unlock(&ops_lock);
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if (!op)
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return -EAGAIN;
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/* there is no need to get a reply from userspace for unlocks
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that were generated by the vfs cleaning up for a close
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(the process did not make an unlock call). */
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if (op->info.flags & DLM_PLOCK_FL_CLOSE)
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kfree(op);
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if (copy_to_user(u, &info, sizeof(info)))
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return -EFAULT;
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return sizeof(info);
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}
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/* a write copies in one plock result that should match a plock_op
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on the recv list */
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static ssize_t dev_write(struct file *file, const char __user *u, size_t count,
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loff_t *ppos)
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{
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struct dlm_plock_info info;
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struct plock_op *op;
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int found = 0, do_callback = 0;
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if (count != sizeof(info))
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return -EINVAL;
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if (copy_from_user(&info, u, sizeof(info)))
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return -EFAULT;
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if (check_version(&info))
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return -EINVAL;
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spin_lock(&ops_lock);
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list_for_each_entry(op, &recv_list, list) {
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if (op->info.fsid == info.fsid &&
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op->info.number == info.number &&
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op->info.owner == info.owner) {
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struct plock_xop *xop = (struct plock_xop *)op;
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list_del_init(&op->list);
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memcpy(&op->info, &info, sizeof(info));
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if (xop->callback)
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do_callback = 1;
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else
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op->done = 1;
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found = 1;
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break;
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}
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}
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spin_unlock(&ops_lock);
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if (found) {
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if (do_callback)
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dlm_plock_callback(op);
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else
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wake_up(&recv_wq);
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} else
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log_print("dev_write no op %x %llx", info.fsid,
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(unsigned long long)info.number);
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return count;
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}
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static unsigned int dev_poll(struct file *file, poll_table *wait)
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{
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unsigned int mask = 0;
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poll_wait(file, &send_wq, wait);
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spin_lock(&ops_lock);
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if (!list_empty(&send_list))
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mask = POLLIN | POLLRDNORM;
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spin_unlock(&ops_lock);
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return mask;
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}
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static const struct file_operations dev_fops = {
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.read = dev_read,
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.write = dev_write,
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.poll = dev_poll,
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.owner = THIS_MODULE,
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.llseek = noop_llseek,
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};
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static struct miscdevice plock_dev_misc = {
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.minor = MISC_DYNAMIC_MINOR,
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.name = DLM_PLOCK_MISC_NAME,
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.fops = &dev_fops
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};
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int dlm_plock_init(void)
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{
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int rv;
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spin_lock_init(&ops_lock);
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INIT_LIST_HEAD(&send_list);
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INIT_LIST_HEAD(&recv_list);
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init_waitqueue_head(&send_wq);
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init_waitqueue_head(&recv_wq);
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rv = misc_register(&plock_dev_misc);
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if (rv)
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log_print("dlm_plock_init: misc_register failed %d", rv);
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return rv;
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}
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void dlm_plock_exit(void)
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{
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if (misc_deregister(&plock_dev_misc) < 0)
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log_print("dlm_plock_exit: misc_deregister failed");
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}
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