fs/gfs2/locking/nolock/main.c

   1 /*
   2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3  * Copyright (C) 2004-2005 Red Hat, Inc.  All rights reserved.
   4  *
   5  * This copyrighted material is made available to anyone wishing to use,
   6  * modify, copy, or redistribute it subject to the terms and conditions
   7  * of the GNU General Public License version 2.
   8  */
   9
  10 #include <linux/module.h>
  11 #include <linux/slab.h>
  12 #include <linux/init.h>
  13 #include <linux/types.h>
  14 #include <linux/fs.h>
  15 #include <linux/lm_interface.h>
  16
  17 struct nolock_lockspace {
  18         unsigned int nl_lvb_size;
  19 };
  20
  21 static const struct lm_lockops nolock_ops;
  22
  23 static int nolock_mount(char *table_name, char *host_data,
  24                         lm_callback_t cb, void *cb_data,
  25                         unsigned int min_lvb_size, int flags,
  26                         struct lm_lockstruct *lockstruct,
  27                         struct kobject *fskobj)
  28 {
  29         char *c;
  30         unsigned int jid;
  31         struct nolock_lockspace *nl;
  32
  33         c = strstr(host_data, "jid=");
  34         if (!c)
  35                 jid = 0;
  36         else {
  37                 c += 4;
  38                 sscanf(c, "%u", &jid);
  39         }
  40
  41         nl = kzalloc(sizeof(struct nolock_lockspace), GFP_KERNEL);
  42         if (!nl)
  43                 return -ENOMEM;
  44
  45         nl->nl_lvb_size = min_lvb_size;
  46
  47         lockstruct->ls_jid = jid;
  48         lockstruct->ls_first = 1;
  49         lockstruct->ls_lvb_size = min_lvb_size;
  50         lockstruct->ls_lockspace = nl;
  51         lockstruct->ls_ops = &nolock_ops;
  52         lockstruct->ls_flags = LM_LSFLAG_LOCAL;
  53
  54         return 0;
  55 }
  56
  57 static void nolock_others_may_mount(void *lockspace)
  58 {
  59 }
  60
  61 static void nolock_unmount(void *lockspace)
  62 {
  63         struct nolock_lockspace *nl = lockspace;
  64         kfree(nl);
  65 }
  66
  67 static void nolock_withdraw(void *lockspace)
  68 {
  69 }
  70
  71 /**
  72  * nolock_get_lock - get a lm_lock_t given a descripton of the lock
  73  * @lockspace: the lockspace the lock lives in
  74  * @name: the name of the lock
  75  * @lockp: return the lm_lock_t here
  76  *
  77  * Returns: 0 on success, -EXXX on failure
  78  */
  79
  80 static int nolock_get_lock(void *lockspace, struct lm_lockname *name,
  81                            void **lockp)
  82 {
  83         *lockp = lockspace;
  84         return 0;
  85 }
  86
  87 /**
  88  * nolock_put_lock - get rid of a lock structure
  89  * @lock: the lock to throw away
  90  *
  91  */
  92
  93 static void nolock_put_lock(void *lock)
  94 {
  95 }
  96
  97 /**
  98  * nolock_lock - acquire a lock
  99  * @lock: the lock to manipulate
 100  * @cur_state: the current state
 101  * @req_state: the requested state
 102  * @flags: modifier flags
 103  *
 104  * Returns: A bitmap of LM_OUT_*
 105  */
 106
 107 static unsigned int nolock_lock(void *lock, unsigned int cur_state,
 108                                 unsigned int req_state, unsigned int flags)
 109 {
 110         if (req_state == LM_ST_UNLOCKED)
 111                 return 0;
 112         return req_state | LM_OUT_CACHEABLE;
 113 }
 114
 115 /**
 116  * nolock_unlock - unlock a lock
 117  * @lock: the lock to manipulate
 118  * @cur_state: the current state
 119  *
 120  * Returns: 0
 121  */
 122
 123 static unsigned int nolock_unlock(void *lock, unsigned int cur_state)
 124 {
 125         return 0;
 126 }
 127
 128 static void nolock_cancel(void *lock)
 129 {
 130 }
 131
 132 /**
 133  * nolock_hold_lvb - hold on to a lock value block
 134  * @lock: the lock the LVB is associated with
 135  * @lvbp: return the lm_lvb_t here
 136  *
 137  * Returns: 0 on success, -EXXX on failure
 138  */
 139
 140 static int nolock_hold_lvb(void *lock, char **lvbp)
 141 {
 142         struct nolock_lockspace *nl = lock;
 143         int error = 0;
 144
 145         *lvbp = kzalloc(nl->nl_lvb_size, GFP_NOFS);
 146         if (!*lvbp)
 147                 error = -ENOMEM;
 148
 149         return error;
 150 }
 151
 152 /**
 153  * nolock_unhold_lvb - release a LVB
 154  * @lock: the lock the LVB is associated with
 155  * @lvb: the lock value block
 156  *
 157  */
 158
 159 static void nolock_unhold_lvb(void *lock, char *lvb)
 160 {
 161         kfree(lvb);
 162 }
 163
 164 static int nolock_plock_get(void *lockspace, struct lm_lockname *name,
 165                             struct file *file, struct file_lock *fl)
 166 {
 167         posix_test_lock(file, fl);
 168
 169         return 0;
 170 }
 171
 172 static int nolock_plock(void *lockspace, struct lm_lockname *name,
 173                         struct file *file, int cmd, struct file_lock *fl)
 174 {
 175         int error;
 176         error = posix_lock_file_wait(file, fl);
 177         return error;
 178 }
 179
 180 static int nolock_punlock(void *lockspace, struct lm_lockname *name,
 181                           struct file *file, struct file_lock *fl)
 182 {
 183         int error;
 184         error = posix_lock_file_wait(file, fl);
 185         return error;
 186 }
 187
 188 static void nolock_recovery_done(void *lockspace, unsigned int jid,
 189                                  unsigned int message)
 190 {
 191 }
 192
 193 static const struct lm_lockops nolock_ops = {
 194         .lm_proto_name = "lock_nolock",
 195         .lm_mount = nolock_mount,
 196         .lm_others_may_mount = nolock_others_may_mount,
 197         .lm_unmount = nolock_unmount,
 198         .lm_withdraw = nolock_withdraw,
 199         .lm_get_lock = nolock_get_lock,
 200         .lm_put_lock = nolock_put_lock,
 201         .lm_lock = nolock_lock,
 202         .lm_unlock = nolock_unlock,
 203         .lm_cancel = nolock_cancel,
 204         .lm_hold_lvb = nolock_hold_lvb,
 205         .lm_unhold_lvb = nolock_unhold_lvb,
 206         .lm_plock_get = nolock_plock_get,
 207         .lm_plock = nolock_plock,
 208         .lm_punlock = nolock_punlock,
 209         .lm_recovery_done = nolock_recovery_done,
 210         .lm_owner = THIS_MODULE,
 211 };
 212
 213 static int __init init_nolock(void)
 214 {
 215         int error;
 216
 217         error = gfs2_register_lockproto(&nolock_ops);
 218         if (error) {
 219                 printk(KERN_WARNING
 220                        "lock_nolock: can't register protocol: %d\n", error);
 221                 return error;
 222         }
 223
 224         printk(KERN_INFO
 225                "Lock_Nolock (built %s %s) installed\n", __DATE__, __TIME__);
 226         return 0;
 227 }
 228
 229 static void __exit exit_nolock(void)
 230 {
 231         gfs2_unregister_lockproto(&nolock_ops);
 232 }
 233
 234 module_init(init_nolock);
 235 module_exit(exit_nolock);
 236
 237 MODULE_DESCRIPTION("GFS Nolock Locking Module");
 238 MODULE_AUTHOR("Red Hat, Inc.");
 239 MODULE_LICENSE("GPL");
 240