xref: /kernel/linux/linux-5.10/fs/ocfs2/locks.c (revision 8c2ecf20) 
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}
131