1// SPDX-License-Identifier: GPL-2.0-or-later
  2/* -*- mode: c; c-basic-offset: 8; -*-
  3 * vim: noexpandtab sw=8 ts=8 sts=0:
  4 *
  5 * locks.c
  6 *
  7 * Userspace file locking support
  8 *
  9 * Copyright (C) 2007 Oracle.  All rights reserved.
 10 */
 11
 12#include <linux/fs.h>
 13#include <linux/fcntl.h>
 14
 15#include <cluster/masklog.h>
 16
 17#include "ocfs2.h"
 18
 19#include "dlmglue.h"
 20#include "file.h"
 21#include "inode.h"
 22#include "locks.h"
 23
 24static int ocfs2_do_flock(struct file *file, struct inode *inode,
 25			  int cmd, struct file_lock *fl)
 26{
 27	int ret = 0, level = 0, trylock = 0;
 28	struct ocfs2_file_private *fp = file->private_data;
 29	struct ocfs2_lock_res *lockres = &fp->fp_flock;
 30
 31	if (fl->fl_type == F_WRLCK)
 32		level = 1;
 33	if (!IS_SETLKW(cmd))
 34		trylock = 1;
 35
 36	mutex_lock(&fp->fp_mutex);
 37
 38	if (lockres->l_flags & OCFS2_LOCK_ATTACHED &&
 39	    lockres->l_level > LKM_NLMODE) {
 40		int old_level = 0;
 41		struct file_lock request;
 42
 43		if (lockres->l_level == LKM_EXMODE)
 44			old_level = 1;
 45
 46		if (level == old_level)
 47			goto out;
 48
 49		/*
 50		 * Converting an existing lock is not guaranteed to be
 51		 * atomic, so we can get away with simply unlocking
 52		 * here and allowing the lock code to try at the new
 53		 * level.
 54		 */
 55
 56		locks_init_lock(&request);
 57		request.fl_type = F_UNLCK;
 58		request.fl_flags = FL_FLOCK;
 59		locks_lock_file_wait(file, &request);
 60
 61		ocfs2_file_unlock(file);
 62	}
 63
 64	ret = ocfs2_file_lock(file, level, trylock);
 65	if (ret) {
 66		if (ret == -EAGAIN && trylock)
 67			ret = -EWOULDBLOCK;
 68		else
 69			mlog_errno(ret);
 70		goto out;
 71	}
 72
 73	ret = locks_lock_file_wait(file, fl);
 74	if (ret)
 75		ocfs2_file_unlock(file);
 76
 77out:
 78	mutex_unlock(&fp->fp_mutex);
 79
 80	return ret;
 81}
 82
 83static int ocfs2_do_funlock(struct file *file, int cmd, struct file_lock *fl)
 84{
 85	int ret;
 86	struct ocfs2_file_private *fp = file->private_data;
 87
 88	mutex_lock(&fp->fp_mutex);
 89	ocfs2_file_unlock(file);
 90	ret = locks_lock_file_wait(file, fl);
 91	mutex_unlock(&fp->fp_mutex);
 92
 93	return ret;
 94}
 95
 96/*
 97 * Overall flow of ocfs2_flock() was influenced by gfs2_flock().
 98 */
 99int ocfs2_flock(struct file *file, int cmd, struct file_lock *fl)
100{
101	struct inode *inode = file->f_mapping->host;
102	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
103
104	if (!(fl->fl_flags & FL_FLOCK))
105		return -ENOLCK;
106	if (__mandatory_lock(inode))
107		return -ENOLCK;
108
109	if ((osb->s_mount_opt & OCFS2_MOUNT_LOCALFLOCKS) ||
110	    ocfs2_mount_local(osb))
111		return locks_lock_file_wait(file, fl);
112
113	if (fl->fl_type == F_UNLCK)
114		return ocfs2_do_funlock(file, cmd, fl);
115	else
116		return ocfs2_do_flock(file, inode, cmd, fl);
117}
118
119int ocfs2_lock(struct file *file, int cmd, struct file_lock *fl)
120{
121	struct inode *inode = file->f_mapping->host;
122	struct ocfs2_super *osb = OCFS2_SB(inode->i_sb);
123
124	if (!(fl->fl_flags & FL_POSIX))
125		return -ENOLCK;
126	if (__mandatory_lock(inode) && fl->fl_type != F_UNLCK)
127		return -ENOLCK;
128
129	return ocfs2_plock(osb->cconn, OCFS2_I(inode)->ip_blkno, file, cmd, fl);
130}