fs/afs/callback.c

   1 /*
   2  * Copyright (c) 2002, 2007 Red Hat, Inc. All rights reserved.
   3  *
   4  * This software may be freely redistributed under the terms of the
   5  * GNU General Public License.
   6  *
   7  * You should have received a copy of the GNU General Public License
   8  * along with this program; if not, write to the Free Software
   9  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  10  *
  11  * Authors: David Woodhouse <dwmw2@infradead.org>
  12  *          David Howells <dhowells@redhat.com>
  13  *
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/init.h>
  19 #include <linux/circ_buf.h>
  20 #include <linux/sched.h>
  21 #include "internal.h"
  22
  23 /*
  24  * Create volume and callback interests on a server.
  25  */
  26 static struct afs_cb_interest *afs_create_interest(struct afs_server *server,
  27                                                    struct afs_vnode *vnode)
  28 {
  29         struct afs_vol_interest *new_vi, *vi;
  30         struct afs_cb_interest *new;
  31         struct hlist_node **pp;
  32
  33         new_vi = kzalloc(sizeof(struct afs_vol_interest), GFP_KERNEL);
  34         if (!new_vi)
  35                 return NULL;
  36
  37         new = kzalloc(sizeof(struct afs_cb_interest), GFP_KERNEL);
  38         if (!new) {
  39                 kfree(new_vi);
  40                 return NULL;
  41         }
  42
  43         new_vi->usage = 1;
  44         new_vi->vid = vnode->volume->vid;
  45         INIT_HLIST_NODE(&new_vi->srv_link);
  46         INIT_HLIST_HEAD(&new_vi->cb_interests);
  47
  48         refcount_set(&new->usage, 1);
  49         new->sb = vnode->vfs_inode.i_sb;
  50         new->vid = vnode->volume->vid;
  51         new->server = afs_get_server(server);
  52         INIT_HLIST_NODE(&new->cb_vlink);
  53
  54         write_lock(&server->cb_break_lock);
  55
  56         for (pp = &server->cb_volumes.first; *pp; pp = &(*pp)->next) {
  57                 vi = hlist_entry(*pp, struct afs_vol_interest, srv_link);
  58                 if (vi->vid < new_vi->vid)
  59                         continue;
  60                 if (vi->vid > new_vi->vid)
  61                         break;
  62                 vi->usage++;
  63                 goto found_vi;
  64         }
  65
  66         new_vi->srv_link.pprev = pp;
  67         new_vi->srv_link.next = *pp;
  68         if (*pp)
  69                 (*pp)->pprev = &new_vi->srv_link.next;
  70         *pp = &new_vi->srv_link;
  71         vi = new_vi;
  72         new_vi = NULL;
  73 found_vi:
  74
  75         new->vol_interest = vi;
  76         hlist_add_head(&new->cb_vlink, &vi->cb_interests);
  77
  78         write_unlock(&server->cb_break_lock);
  79         kfree(new_vi);
  80         return new;
  81 }
  82
  83 /*
  84  * Set up an interest-in-callbacks record for a volume on a server and
  85  * register it with the server.
  86  * - Called with vnode->io_lock held.
  87  */
  88 int afs_register_server_cb_interest(struct afs_vnode *vnode,
  89                                     struct afs_server_list *slist,
  90                                     unsigned int index)
  91 {
  92         struct afs_server_entry *entry = &slist->servers[index];
  93         struct afs_cb_interest *cbi, *vcbi, *new, *old;
  94         struct afs_server *server = entry->server;
  95
  96 again:
  97         if (vnode->cb_interest &&
  98             likely(vnode->cb_interest == entry->cb_interest))
  99                 return 0;
 100
 101         read_lock(&slist->lock);
 102         cbi = afs_get_cb_interest(entry->cb_interest);
 103         read_unlock(&slist->lock);
 104
 105         vcbi = vnode->cb_interest;
 106         if (vcbi) {
 107                 if (vcbi == cbi) {
 108                         afs_put_cb_interest(afs_v2net(vnode), cbi);
 109                         return 0;
 110                 }
 111
 112                 /* Use a new interest in the server list for the same server
 113                  * rather than an old one that's still attached to a vnode.
 114                  */
 115                 if (cbi && vcbi->server == cbi->server) {
 116                         write_seqlock(&vnode->cb_lock);
 117                         old = vnode->cb_interest;
 118                         vnode->cb_interest = cbi;
 119                         write_sequnlock(&vnode->cb_lock);
 120                         afs_put_cb_interest(afs_v2net(vnode), old);
 121                         return 0;
 122                 }
 123
 124                 /* Re-use the one attached to the vnode. */
 125                 if (!cbi && vcbi->server == server) {
 126                         write_lock(&slist->lock);
 127                         if (entry->cb_interest) {
 128                                 write_unlock(&slist->lock);
 129                                 afs_put_cb_interest(afs_v2net(vnode), cbi);
 130                                 goto again;
 131                         }
 132
 133                         entry->cb_interest = cbi;
 134                         write_unlock(&slist->lock);
 135                         return 0;
 136                 }
 137         }
 138
 139         if (!cbi) {
 140                 new = afs_create_interest(server, vnode);
 141                 if (!new)
 142                         return -ENOMEM;
 143
 144                 write_lock(&slist->lock);
 145                 if (!entry->cb_interest) {
 146                         entry->cb_interest = afs_get_cb_interest(new);
 147                         cbi = new;
 148                         new = NULL;
 149                 } else {
 150                         cbi = afs_get_cb_interest(entry->cb_interest);
 151                 }
 152                 write_unlock(&slist->lock);
 153                 afs_put_cb_interest(afs_v2net(vnode), new);
 154         }
 155
 156         ASSERT(cbi);
 157
 158         /* Change the server the vnode is using.  This entails scrubbing any
 159          * interest the vnode had in the previous server it was using.
 160          */
 161         write_seqlock(&vnode->cb_lock);
 162
 163         old = vnode->cb_interest;
 164         vnode->cb_interest = cbi;
 165         vnode->cb_s_break = cbi->server->cb_s_break;
 166         vnode->cb_v_break = vnode->volume->cb_v_break;
 167         clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
 168
 169         write_sequnlock(&vnode->cb_lock);
 170         afs_put_cb_interest(afs_v2net(vnode), old);
 171         return 0;
 172 }
 173
 174 /*
 175  * Remove an interest on a server.
 176  */
 177 void afs_put_cb_interest(struct afs_net *net, struct afs_cb_interest *cbi)
 178 {
 179         struct afs_vol_interest *vi;
 180
 181         if (cbi && refcount_dec_and_test(&cbi->usage)) {
 182                 if (!hlist_unhashed(&cbi->cb_vlink)) {
 183                         write_lock(&cbi->server->cb_break_lock);
 184
 185                         hlist_del_init(&cbi->cb_vlink);
 186                         vi = cbi->vol_interest;
 187                         cbi->vol_interest = NULL;
 188                         if (--vi->usage == 0)
 189                                 hlist_del(&vi->srv_link);
 190                         else
 191                                 vi = NULL;
 192
 193                         write_unlock(&cbi->server->cb_break_lock);
 194                         kfree(vi);
 195                         afs_put_server(net, cbi->server);
 196                 }
 197                 kfree(cbi);
 198         }
 199 }
 200
 201 /*
 202  * allow the fileserver to request callback state (re-)initialisation
 203  */
 204 void afs_init_callback_state(struct afs_server *server)
 205 {
 206         if (!test_and_clear_bit(AFS_SERVER_FL_NEW, &server->flags))
 207                 server->cb_s_break++;
 208 }
 209
 210 /*
 211  * actually break a callback
 212  */
 213 void afs_break_callback(struct afs_vnode *vnode)
 214 {
 215         _enter("");
 216
 217         write_seqlock(&vnode->cb_lock);
 218
 219         clear_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
 220         if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) {
 221                 vnode->cb_break++;
 222                 afs_clear_permits(vnode);
 223
 224                 spin_lock(&vnode->lock);
 225
 226                 _debug("break callback");
 227
 228                 if (list_empty(&vnode->granted_locks) &&
 229                     !list_empty(&vnode->pending_locks))
 230                         afs_lock_may_be_available(vnode);
 231                 spin_unlock(&vnode->lock);
 232         }
 233
 234         write_sequnlock(&vnode->cb_lock);
 235 }
 236
 237 /*
 238  * allow the fileserver to explicitly break one callback
 239  * - happens when
 240  *   - the backing file is changed
 241  *   - a lock is released
 242  */
 243 static void afs_break_one_callback(struct afs_server *server,
 244                                    struct afs_fid *fid)
 245 {
 246         struct afs_vol_interest *vi;
 247         struct afs_cb_interest *cbi;
 248         struct afs_iget_data data;
 249         struct afs_vnode *vnode;
 250         struct inode *inode;
 251
 252         read_lock(&server->cb_break_lock);
 253         hlist_for_each_entry(vi, &server->cb_volumes, srv_link) {
 254                 if (vi->vid < fid->vid)
 255                         continue;
 256                 if (vi->vid > fid->vid) {
 257                         vi = NULL;
 258                         break;
 259                 }
 260                 //atomic_inc(&vi->usage);
 261                 break;
 262         }
 263
 264         /* TODO: Find all matching volumes if we couldn't match the server and
 265          * break them anyway.
 266          */
 267         if (!vi)
 268                 goto out;
 269
 270         /* Step through all interested superblocks.  There may be more than one
 271          * because of cell aliasing.
 272          */
 273         hlist_for_each_entry(cbi, &vi->cb_interests, cb_vlink) {
 274                 if (fid->vnode == 0 && fid->unique == 0) {
 275                         /* The callback break applies to an entire volume. */
 276                         struct afs_super_info *as = AFS_FS_S(cbi->sb);
 277                         struct afs_volume *volume = as->volume;
 278
 279                         write_lock(&volume->cb_break_lock);
 280                         volume->cb_v_break++;
 281                         write_unlock(&volume->cb_break_lock);
 282                 } else {
 283                         data.volume = NULL;
 284                         data.fid = *fid;
 285                         inode = ilookup5_nowait(cbi->sb, fid->vnode,
 286                                                 afs_iget5_test, &data);
 287                         if (inode) {
 288                                 vnode = AFS_FS_I(inode);
 289                                 afs_break_callback(vnode);
 290                                 iput(inode);
 291                         }
 292                 }
 293         }
 294
 295 out:
 296         read_unlock(&server->cb_break_lock);
 297 }
 298
 299 /*
 300  * allow the fileserver to break callback promises
 301  */
 302 void afs_break_callbacks(struct afs_server *server, size_t count,
 303                          struct afs_callback_break *callbacks)
 304 {
 305         _enter("%p,%zu,", server, count);
 306
 307         ASSERT(server != NULL);
 308         ASSERTCMP(count, <=, AFSCBMAX);
 309
 310         /* TODO: Sort the callback break list by volume ID */
 311
 312         for (; count > 0; callbacks++, count--) {
 313                 _debug("- Fid { vl=%08x n=%u u=%u }  CB { v=%u x=%u t=%u }",
 314                        callbacks->fid.vid,
 315                        callbacks->fid.vnode,
 316                        callbacks->fid.unique,
 317                        callbacks->cb.version,
 318                        callbacks->cb.expiry,
 319                        callbacks->cb.type
 320                        );
 321                 afs_break_one_callback(server, &callbacks->fid);
 322         }
 323
 324         _leave("");
 325         return;
 326 }
 327
 328 /*
 329  * Clear the callback interests in a server list.
 330  */
 331 void afs_clear_callback_interests(struct afs_net *net, struct afs_server_list *slist)
 332 {
 333         int i;
 334
 335         for (i = 0; i < slist->nr_servers; i++) {
 336                 afs_put_cb_interest(net, slist->servers[i].cb_interest);
 337                 slist->servers[i].cb_interest = NULL;
 338         }
 339 }