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