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