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1 | /* -*- mode: c; c-basic-offset: 8; -*- |
2 | * vim: noexpandtab sw=8 ts=8 sts=0: | |
3 | * | |
4 | * locks.c | |
5 | * | |
6 | * Userspace file locking support | |
7 | * | |
8 | * Copyright (C) 2007 Oracle. All rights reserved. | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU General Public | |
12 | * License as published by the Free Software Foundation; either | |
13 | * version 2 of the License, or (at your option) any later version. | |
14 | * | |
15 | * This program is distributed in the hope that it will be useful, | |
16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | * General Public License for more details. | |
19 | * | |
20 | * You should have received a copy of the GNU General Public | |
21 | * License along with this program; if not, write to the | |
22 | * Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
23 | * Boston, MA 021110-1307, USA. | |
24 | */ | |
25 | ||
26 | #include <linux/fs.h> | |
27 | ||
28 | #define MLOG_MASK_PREFIX ML_INODE | |
29 | #include <cluster/masklog.h> | |
30 | ||
31 | #include "ocfs2.h" | |
32 | ||
33 | #include "dlmglue.h" | |
34 | #include "file.h" | |
35 | #include "locks.h" | |
36 | ||
37 | static int ocfs2_do_flock(struct file *file, struct inode *inode, | |
38 | int cmd, struct file_lock *fl) | |
39 | { | |
40 | int ret = 0, level = 0, trylock = 0; | |
41 | struct ocfs2_file_private *fp = file->private_data; | |
42 | struct ocfs2_lock_res *lockres = &fp->fp_flock; | |
43 | ||
44 | if (fl->fl_type == F_WRLCK) | |
45 | level = 1; | |
46 | if (!IS_SETLKW(cmd)) | |
47 | trylock = 1; | |
48 | ||
49 | mutex_lock(&fp->fp_mutex); | |
50 | ||
51 | if (lockres->l_flags & OCFS2_LOCK_ATTACHED && | |
52 | lockres->l_level > LKM_NLMODE) { | |
53 | int old_level = 0; | |
54 | ||
55 | if (lockres->l_level == LKM_EXMODE) | |
56 | old_level = 1; | |
57 | ||
58 | if (level == old_level) | |
59 | goto out; | |
60 | ||
61 | /* | |
62 | * Converting an existing lock is not guaranteed to be | |
63 | * atomic, so we can get away with simply unlocking | |
64 | * here and allowing the lock code to try at the new | |
65 | * level. | |
66 | */ | |
67 | ||
68 | flock_lock_file_wait(file, | |
69 | &(struct file_lock){.fl_type = F_UNLCK}); | |
70 | ||
71 | ocfs2_file_unlock(file); | |
72 | } | |
73 | ||
74 | ret = ocfs2_file_lock(file, level, trylock); | |
75 | if (ret) { | |
76 | if (ret == -EAGAIN && trylock) | |
77 | ret = -EWOULDBLOCK; | |
78 | else | |
79 | mlog_errno(ret); | |
80 | goto out; | |
81 | } | |
82 | ||
83 | ret = flock_lock_file_wait(file, fl); | |
84 | ||
85 | out: | |
86 | mutex_unlock(&fp->fp_mutex); | |
87 | ||
88 | return ret; | |
89 | } | |
90 | ||
91 | static int ocfs2_do_funlock(struct file *file, int cmd, struct file_lock *fl) | |
92 | { | |
93 | int ret; | |
94 | struct ocfs2_file_private *fp = file->private_data; | |
95 | ||
96 | mutex_lock(&fp->fp_mutex); | |
97 | ocfs2_file_unlock(file); | |
98 | ret = flock_lock_file_wait(file, fl); | |
99 | mutex_unlock(&fp->fp_mutex); | |
100 | ||
101 | return ret; | |
102 | } | |
103 | ||
104 | /* | |
105 | * Overall flow of ocfs2_flock() was influenced by gfs2_flock(). | |
106 | */ | |
107 | int ocfs2_flock(struct file *file, int cmd, struct file_lock *fl) | |
108 | { | |
109 | struct inode *inode = file->f_mapping->host; | |
110 | struct ocfs2_super *osb = OCFS2_SB(inode->i_sb); | |
111 | ||
112 | if (!(fl->fl_flags & FL_FLOCK)) | |
113 | return -ENOLCK; | |
114 | if (__mandatory_lock(inode)) | |
115 | return -ENOLCK; | |
116 | ||
117 | if ((osb->s_mount_opt & OCFS2_MOUNT_LOCALFLOCKS) || | |
118 | ocfs2_mount_local(osb)) | |
119 | return flock_lock_file_wait(file, fl); | |
120 | ||
121 | if (fl->fl_type == F_UNLCK) | |
122 | return ocfs2_do_funlock(file, cmd, fl); | |
123 | else | |
124 | return ocfs2_do_flock(file, inode, cmd, fl); | |
125 | } |