445 lines
9.8 KiB
C
445 lines
9.8 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 "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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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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wait_event(recv_wq, (op->done != 0));
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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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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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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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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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};
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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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