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