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 v.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/smp_lock.h>
  17
  18 #include "../../lm_interface.h"
  19
  20 struct nolock_lockspace {
  21         unsigned int nl_lvb_size;
  22 };
  23
  24 struct lm_lockops nolock_ops;
  25
  26 static int nolock_mount(char *table_name, char *host_data,
  27                         lm_callback_t cb, lm_fsdata_t *fsdata,
  28                         unsigned int min_lvb_size, int flags,
  29                         struct lm_lockstruct *lockstruct,
  30                         struct kobject *fskobj)
  31 {
  32         char *c;
  33         unsigned int jid;
  34         struct nolock_lockspace *nl;
  35
  36         /* If there is a "jid=" in the hostdata, return that jid.
  37            Otherwise, return zero. */
  38
  39         c = strstr(host_data, "jid=");
  40         if (!c)
  41                 jid = 0;
  42         else {
  43                 c += 4;
  44                 sscanf(c, "%u", &jid);
  45         }
  46
  47         nl = kmalloc(sizeof(struct nolock_lockspace), GFP_KERNEL);
  48         if (!nl)
  49                 return -ENOMEM;
  50
  51         memset(nl, 0, sizeof(struct nolock_lockspace));
  52         nl->nl_lvb_size = min_lvb_size;
  53
  54         lockstruct->ls_jid = jid;
  55         lockstruct->ls_first = 1;
  56         lockstruct->ls_lvb_size = min_lvb_size;
  57         lockstruct->ls_lockspace = (lm_lockspace_t *)nl;
  58         lockstruct->ls_ops = &nolock_ops;
  59         lockstruct->ls_flags = LM_LSFLAG_LOCAL;
  60
  61         return 0;
  62 }
  63
  64 static void nolock_others_may_mount(lm_lockspace_t *lockspace)
  65 {
  66 }
  67
  68 static void nolock_unmount(lm_lockspace_t *lockspace)
  69 {
  70         struct nolock_lockspace *nl = (struct nolock_lockspace *)lockspace;
  71         kfree(nl);
  72 }
  73
  74 static void nolock_withdraw(lm_lockspace_t *lockspace)
  75 {
  76 }
  77
  78 /**
  79  * nolock_get_lock - get a lm_lock_t given a descripton of the lock
  80  * @lockspace: the lockspace the lock lives in
  81  * @name: the name of the lock
  82  * @lockp: return the lm_lock_t here
  83  *
  84  * Returns: 0 on success, -EXXX on failure
  85  */
  86
  87 static int nolock_get_lock(lm_lockspace_t *lockspace, struct lm_lockname *name,
  88                            lm_lock_t **lockp)
  89 {
  90         *lockp = (lm_lock_t *)lockspace;
  91         return 0;
  92 }
  93
  94 /**
  95  * nolock_put_lock - get rid of a lock structure
  96  * @lock: the lock to throw away
  97  *
  98  */
  99
 100 static void nolock_put_lock(lm_lock_t *lock)
 101 {
 102 }
 103
 104 /**
 105  * nolock_lock - acquire a lock
 106  * @lock: the lock to manipulate
 107  * @cur_state: the current state
 108  * @req_state: the requested state
 109  * @flags: modifier flags
 110  *
 111  * Returns: A bitmap of LM_OUT_*
 112  */
 113
 114 static unsigned int nolock_lock(lm_lock_t *lock, unsigned int cur_state,
 115                                 unsigned int req_state, unsigned int flags)
 116 {
 117         return req_state | LM_OUT_CACHEABLE;
 118 }
 119
 120 /**
 121  * nolock_unlock - unlock a lock
 122  * @lock: the lock to manipulate
 123  * @cur_state: the current state
 124  *
 125  * Returns: 0
 126  */
 127
 128 static unsigned int nolock_unlock(lm_lock_t *lock, unsigned int cur_state)
 129 {
 130         return 0;
 131 }
 132
 133 static void nolock_cancel(lm_lock_t *lock)
 134 {
 135 }
 136
 137 /**
 138  * nolock_hold_lvb - hold on to a lock value block
 139  * @lock: the lock the LVB is associated with
 140  * @lvbp: return the lm_lvb_t here
 141  *
 142  * Returns: 0 on success, -EXXX on failure
 143  */
 144
 145 static int nolock_hold_lvb(lm_lock_t *lock, char **lvbp)
 146 {
 147         struct nolock_lockspace *nl = (struct nolock_lockspace *)lock;
 148         int error = 0;
 149
 150         *lvbp = kmalloc(nl->nl_lvb_size, GFP_KERNEL);
 151         if (*lvbp)
 152                 memset(*lvbp, 0, nl->nl_lvb_size);
 153         else
 154                 error = -ENOMEM;
 155
 156         return error;
 157 }
 158
 159 /**
 160  * nolock_unhold_lvb - release a LVB
 161  * @lock: the lock the LVB is associated with
 162  * @lvb: the lock value block
 163  *
 164  */
 165
 166 static void nolock_unhold_lvb(lm_lock_t *lock, char *lvb)
 167 {
 168         kfree(lvb);
 169 }
 170
 171 /**
 172  * nolock_sync_lvb - sync out the value of a lvb
 173  * @lock: the lock the LVB is associated with
 174  * @lvb: the lock value block
 175  *
 176  */
 177
 178 static void nolock_sync_lvb(lm_lock_t *lock, char *lvb)
 179 {
 180 }
 181
 182 static int nolock_plock_get(lm_lockspace_t *lockspace, struct lm_lockname *name,
 183                             struct file *file, struct file_lock *fl)
 184 {
 185         struct file_lock *tmp;
 186
 187         lock_kernel();
 188         tmp = posix_test_lock(file, fl);
 189         fl->fl_type = F_UNLCK;
 190         if (tmp)
 191                 memcpy(fl, tmp, sizeof(struct file_lock));
 192         unlock_kernel();
 193
 194         return 0;
 195 }
 196
 197 static int nolock_plock(lm_lockspace_t *lockspace, struct lm_lockname *name,
 198                         struct file *file, int cmd, struct file_lock *fl)
 199 {
 200         int error;
 201         lock_kernel();
 202         error = posix_lock_file_wait(file, fl);
 203         unlock_kernel();
 204         return error;
 205 }
 206
 207 static int nolock_punlock(lm_lockspace_t *lockspace, struct lm_lockname *name,
 208                           struct file *file, struct file_lock *fl)
 209 {
 210         int error;
 211         lock_kernel();
 212         error = posix_lock_file_wait(file, fl);
 213         unlock_kernel();
 214         return error;
 215 }
 216
 217 static void nolock_recovery_done(lm_lockspace_t *lockspace, unsigned int jid,
 218                                  unsigned int message)
 219 {
 220 }
 221
 222 struct lm_lockops nolock_ops = {
 223         .lm_proto_name = "lock_nolock",
 224         .lm_mount = nolock_mount,
 225         .lm_others_may_mount = nolock_others_may_mount,
 226         .lm_unmount = nolock_unmount,
 227         .lm_withdraw = nolock_withdraw,
 228         .lm_get_lock = nolock_get_lock,
 229         .lm_put_lock = nolock_put_lock,
 230         .lm_lock = nolock_lock,
 231         .lm_unlock = nolock_unlock,
 232         .lm_cancel = nolock_cancel,
 233         .lm_hold_lvb = nolock_hold_lvb,
 234         .lm_unhold_lvb = nolock_unhold_lvb,
 235         .lm_sync_lvb = nolock_sync_lvb,
 236         .lm_plock_get = nolock_plock_get,
 237         .lm_plock = nolock_plock,
 238         .lm_punlock = nolock_punlock,
 239         .lm_recovery_done = nolock_recovery_done,
 240         .lm_owner = THIS_MODULE,
 241 };
 242
 243 int __init init_nolock(void)
 244 {
 245         int error;
 246
 247         error = gfs_register_lockproto(&nolock_ops);
 248         if (error) {
 249                 printk("lock_nolock: can't register protocol: %d\n", error);
 250                 return error;
 251         }
 252
 253         printk("Lock_Nolock (built %s %s) installed\n", __DATE__, __TIME__);
 254         return 0;
 255 }
 256
 257 void __exit exit_nolock(void)
 258 {
 259         gfs_unregister_lockproto(&nolock_ops);
 260 }
 261
 262 module_init(init_nolock);
 263 module_exit(exit_nolock);
 264
 265 MODULE_DESCRIPTION("GFS Nolock Locking Module");
 266 MODULE_AUTHOR("Red Hat, Inc.");
 267 MODULE_LICENSE("GPL");
 268