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 (fl->fl_type == F_WRLCK) |
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.fl_type = F_UNLCK; |
57 | request.fl_flags = FL_FLOCK; |
58 | locks_lock_file_wait(filp: file, fl: &request); |
59 | |
60 | ocfs2_file_unlock(file); |
61 | } |
62 | |
63 | ret = ocfs2_file_lock(file, ex: 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(filp: file, fl); |
73 | if (ret) |
74 | ocfs2_file_unlock(file); |
75 | |
76 | out: |
77 | mutex_unlock(lock: &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(filp: file, fl); |
90 | mutex_unlock(lock: &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->fl_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(filp: file, fl); |
109 | |
110 | if (fl->fl_type == F_UNLCK) |
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->fl_flags & FL_POSIX)) |
122 | return -ENOLCK; |
123 | |
124 | return ocfs2_plock(conn: osb->cconn, ino: OCFS2_I(inode)->ip_blkno, file, cmd, fl); |
125 | } |
126 | |