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
ocfs2_do_flock(struct file * file,struct inode * inode,int cmd,struct file_lock * fl)24 static 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
77 out:
78 mutex_unlock(&fp->fp_mutex);
79
80 return ret;
81 }
82
ocfs2_do_funlock(struct file * file,int cmd,struct file_lock * fl)83 static 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 */
ocfs2_flock(struct file * file,int cmd,struct file_lock * fl)99 int 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
ocfs2_lock(struct file * file,int cmd,struct file_lock * fl)119 int 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