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/smp_lock.h>
  17 #include <linux/lm_interface.h>
  18
  19 struct nolock_lockspace {
  20         unsigned int nl_lvb_size;
  21 };
  22
  23 static const struct lm_lockops nolock_ops;
  24
  25 static int nolock_mount(char *table_name, char *host_data,
  26                         lm_callback_t cb, void *cb_data,
  27                         unsigned int min_lvb_size, int flags,
  28                         struct lm_lockstruct *lockstruct,
  29                         struct kobject *fskobj)
  30 {
  31         char *c;
  32         unsigned int jid;
  33         struct nolock_lockspace *nl;
  34
  35         c = strstr(host_data, "jid=");
  36         if (!c)
  37                 jid = 0;
  38         else {
  39                 c += 4;
  40                 sscanf(c, "%u", &jid);
  41         }
  42
  43         nl = kzalloc(sizeof(struct nolock_lockspace), GFP_KERNEL);
  44         if (!nl)
  45                 return -ENOMEM;
  46
  47         nl->nl_lvb_size = min_lvb_size;
  48
  49         lockstruct->ls_jid = jid;
  50         lockstruct->ls_first = 1;
  51         lockstruct->ls_lvb_size = min_lvb_size;
  52         lockstruct->ls_lockspace = nl;
  53         lockstruct->ls_ops = &nolock_ops;
  54         lockstruct->ls_flags = LM_LSFLAG_LOCAL;
  55
  56         return 0;
  57 }
  58
  59 static void nolock_others_may_mount(void *lockspace)
  60 {
  61 }
  62
  63 static void nolock_unmount(void *lockspace)
  64 {
  65         struct nolock_lockspace *nl = lockspace;
  66         kfree(nl);
  67 }
  68
  69 static void nolock_withdraw(void *lockspace)
  70 {
  71 }
  72
  73 /**
  74  * nolock_get_lock - get a lm_lock_t given a descripton of the lock
  75  * @lockspace: the lockspace the lock lives in
  76  * @name: the name of the lock
  77  * @lockp: return the lm_lock_t here
  78  *
  79  * Returns: 0 on success, -EXXX on failure
  80  */
  81
  82 static int nolock_get_lock(void *lockspace, struct lm_lockname *name,
  83                            void **lockp)
  84 {
  85         *lockp = lockspace;
  86         return 0;
  87 }
  88
  89 /**
  90  * nolock_put_lock - get rid of a lock structure
  91  * @lock: the lock to throw away
  92  *
  93  */
  94
  95 static void nolock_put_lock(void *lock)
  96 {
  97 }
  98
  99 /**
 100  * nolock_lock - acquire a lock
 101  * @lock: the lock to manipulate
 102  * @cur_state: the current state
 103  * @req_state: the requested state
 104  * @flags: modifier flags
 105  *
 106  * Returns: A bitmap of LM_OUT_*
 107  */
 108
 109 static unsigned int nolock_lock(void *lock, unsigned int cur_state,
 110                                 unsigned int req_state, unsigned int flags)
 111 {
 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_KERNEL);
 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         struct file_lock tmp;
 168         int ret;
 169
 170         ret = posix_test_lock(file, fl, &tmp);
 171         fl->fl_type = F_UNLCK;
 172         if (ret)
 173                 memcpy(fl, &tmp, sizeof(struct file_lock));
 174
 175         return 0;
 176 }
 177
 178 static int nolock_plock(void *lockspace, struct lm_lockname *name,
 179                         struct file *file, int cmd, struct file_lock *fl)
 180 {
 181         int error;
 182         error = posix_lock_file_wait(file, fl);
 183         return error;
 184 }
 185
 186 static int nolock_punlock(void *lockspace, struct lm_lockname *name,
 187                           struct file *file, struct file_lock *fl)
 188 {
 189         int error;
 190         error = posix_lock_file_wait(file, fl);
 191         return error;
 192 }
 193
 194 static void nolock_recovery_done(void *lockspace, unsigned int jid,
 195                                  unsigned int message)
 196 {
 197 }
 198
 199 static const struct lm_lockops nolock_ops = {
 200         .lm_proto_name = "lock_nolock",
 201         .lm_mount = nolock_mount,
 202         .lm_others_may_mount = nolock_others_may_mount,
 203         .lm_unmount = nolock_unmount,
 204         .lm_withdraw = nolock_withdraw,
 205         .lm_get_lock = nolock_get_lock,
 206         .lm_put_lock = nolock_put_lock,
 207         .lm_lock = nolock_lock,
 208         .lm_unlock = nolock_unlock,
 209         .lm_cancel = nolock_cancel,
 210         .lm_hold_lvb = nolock_hold_lvb,
 211         .lm_unhold_lvb = nolock_unhold_lvb,
 212         .lm_plock_get = nolock_plock_get,
 213         .lm_plock = nolock_plock,
 214         .lm_punlock = nolock_punlock,
 215         .lm_recovery_done = nolock_recovery_done,
 216         .lm_owner = THIS_MODULE,
 217 };
 218
 219 static int __init init_nolock(void)
 220 {
 221         int error;
 222
 223         error = gfs2_register_lockproto(&nolock_ops);
 224         if (error) {
 225                 printk(KERN_WARNING
 226                        "lock_nolock: can't register protocol: %d\n", error);
 227                 return error;
 228         }
 229
 230         printk(KERN_INFO
 231                "Lock_Nolock (built %s %s) installed\n", __DATE__, __TIME__);
 232         return 0;
 233 }
 234
 235 static void __exit exit_nolock(void)
 236 {
 237         gfs2_unregister_lockproto(&nolock_ops);
 238 }
 239
 240 module_init(init_nolock);
 241 module_exit(exit_nolock);
 242
 243 MODULE_DESCRIPTION("GFS Nolock Locking Module");
 244 MODULE_AUTHOR("Red Hat, Inc.");
 245 MODULE_LICENSE("GPL");
 246