GNU Linux-libre 5.10.219-gnu1
[releases.git] / fs / ocfs2 / locks.c
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
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
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  */
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
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 }