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
23 static 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
76 out:
77 mutex_unlock(&fp->fp_mutex);
78
79 return ret;
80 }
81
82 static 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 */
98 int 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
116 int 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
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