fs/9p/v9fs.c

   1 /*
   2  *  linux/fs/9p/v9fs.c
   3  *
   4  *  This file contains functions assisting in mapping VFS to 9P2000
   5  *
   6  *  Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>
   7  *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License version 2
  11  *  as published by the Free Software Foundation.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to:
  20  *  Free Software Foundation
  21  *  51 Franklin Street, Fifth Floor
  22  *  Boston, MA  02111-1301  USA
  23  *
  24  */
  25
  26 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  27
  28 #include <linux/module.h>
  29 #include <linux/errno.h>
  30 #include <linux/fs.h>
  31 #include <linux/sched.h>
  32 #include <linux/cred.h>
  33 #include <linux/parser.h>
  34 #include <linux/idr.h>
  35 #include <linux/slab.h>
  36 #include <linux/seq_file.h>
  37 #include <net/9p/9p.h>
  38 #include <net/9p/client.h>
  39 #include <net/9p/transport.h>
  40 #include "v9fs.h"
  41 #include "v9fs_vfs.h"
  42 #include "cache.h"
  43
  44 static DEFINE_SPINLOCK(v9fs_sessionlist_lock);
  45 static LIST_HEAD(v9fs_sessionlist);
  46 struct kmem_cache *v9fs_inode_cache;
  47
  48 /*
  49  * Option Parsing (code inspired by NFS code)
  50  *  NOTE: each transport will parse its own options
  51  */
  52
  53 enum {
  54         /* Options that take integer arguments */
  55         Opt_debug, Opt_dfltuid, Opt_dfltgid, Opt_afid,
  56         /* String options */
  57         Opt_uname, Opt_remotename, Opt_cache, Opt_cachetag,
  58         /* Options that take no arguments */
  59         Opt_nodevmap,
  60         /* Cache options */
  61         Opt_cache_loose, Opt_fscache, Opt_mmap,
  62         /* Access options */
  63         Opt_access, Opt_posixacl,
  64         /* Error token */
  65         Opt_err
  66 };
  67
  68 static const match_table_t tokens = {
  69         {Opt_debug, "debug=%x"},
  70         {Opt_dfltuid, "dfltuid=%u"},
  71         {Opt_dfltgid, "dfltgid=%u"},
  72         {Opt_afid, "afid=%u"},
  73         {Opt_uname, "uname=%s"},
  74         {Opt_remotename, "aname=%s"},
  75         {Opt_nodevmap, "nodevmap"},
  76         {Opt_cache, "cache=%s"},
  77         {Opt_cache_loose, "loose"},
  78         {Opt_fscache, "fscache"},
  79         {Opt_mmap, "mmap"},
  80         {Opt_cachetag, "cachetag=%s"},
  81         {Opt_access, "access=%s"},
  82         {Opt_posixacl, "posixacl"},
  83         {Opt_err, NULL}
  84 };
  85
  86 static const char *const v9fs_cache_modes[nr__p9_cache_modes] = {
  87         [CACHE_NONE]    = "none",
  88         [CACHE_MMAP]    = "mmap",
  89         [CACHE_LOOSE]   = "loose",
  90         [CACHE_FSCACHE] = "fscache",
  91 };
  92
  93 /* Interpret mount options for cache mode */
  94 static int get_cache_mode(char *s)
  95 {
  96         int version = -EINVAL;
  97
  98         if (!strcmp(s, "loose")) {
  99                 version = CACHE_LOOSE;
 100                 p9_debug(P9_DEBUG_9P, "Cache mode: loose\n");
 101         } else if (!strcmp(s, "fscache")) {
 102                 version = CACHE_FSCACHE;
 103                 p9_debug(P9_DEBUG_9P, "Cache mode: fscache\n");
 104         } else if (!strcmp(s, "mmap")) {
 105                 version = CACHE_MMAP;
 106                 p9_debug(P9_DEBUG_9P, "Cache mode: mmap\n");
 107         } else if (!strcmp(s, "none")) {
 108                 version = CACHE_NONE;
 109                 p9_debug(P9_DEBUG_9P, "Cache mode: none\n");
 110         } else
 111                 pr_info("Unknown Cache mode %s\n", s);
 112         return version;
 113 }
 114
 115 /*
 116  * Display the mount options in /proc/mounts.
 117  */
 118 int v9fs_show_options(struct seq_file *m, struct dentry *root)
 119 {
 120         struct v9fs_session_info *v9ses = root->d_sb->s_fs_info;
 121
 122         if (v9ses->debug)
 123                 seq_printf(m, ",debug=%x", v9ses->debug);
 124         if (!uid_eq(v9ses->dfltuid, V9FS_DEFUID))
 125                 seq_printf(m, ",dfltuid=%u",
 126                            from_kuid_munged(&init_user_ns, v9ses->dfltuid));
 127         if (!gid_eq(v9ses->dfltgid, V9FS_DEFGID))
 128                 seq_printf(m, ",dfltgid=%u",
 129                            from_kgid_munged(&init_user_ns, v9ses->dfltgid));
 130         if (v9ses->afid != ~0)
 131                 seq_printf(m, ",afid=%u", v9ses->afid);
 132         if (strcmp(v9ses->uname, V9FS_DEFUSER) != 0)
 133                 seq_printf(m, ",uname=%s", v9ses->uname);
 134         if (strcmp(v9ses->aname, V9FS_DEFANAME) != 0)
 135                 seq_printf(m, ",aname=%s", v9ses->aname);
 136         if (v9ses->nodev)
 137                 seq_puts(m, ",nodevmap");
 138         if (v9ses->cache)
 139                 seq_printf(m, ",%s", v9fs_cache_modes[v9ses->cache]);
 140 #ifdef CONFIG_9P_FSCACHE
 141         if (v9ses->cachetag && v9ses->cache == CACHE_FSCACHE)
 142                 seq_printf(m, ",cachetag=%s", v9ses->cachetag);
 143 #endif
 144
 145         switch (v9ses->flags & V9FS_ACCESS_MASK) {
 146         case V9FS_ACCESS_USER:
 147                 seq_puts(m, ",access=user");
 148                 break;
 149         case V9FS_ACCESS_ANY:
 150                 seq_puts(m, ",access=any");
 151                 break;
 152         case V9FS_ACCESS_CLIENT:
 153                 seq_puts(m, ",access=client");
 154                 break;
 155         case V9FS_ACCESS_SINGLE:
 156                 seq_printf(m, ",access=%u",
 157                            from_kuid_munged(&init_user_ns, v9ses->uid));
 158                 break;
 159         }
 160
 161         if (v9ses->flags & V9FS_POSIX_ACL)
 162                 seq_puts(m, ",posixacl");
 163
 164         return p9_show_client_options(m, v9ses->clnt);
 165 }
 166
 167 /**
 168  * v9fs_parse_options - parse mount options into session structure
 169  * @v9ses: existing v9fs session information
 170  *
 171  * Return 0 upon success, -ERRNO upon failure.
 172  */
 173
 174 static int v9fs_parse_options(struct v9fs_session_info *v9ses, char *opts)
 175 {
 176         char *options, *tmp_options;
 177         substring_t args[MAX_OPT_ARGS];
 178         char *p;
 179         int option = 0;
 180         char *s, *e;
 181         int ret = 0;
 182
 183         /* setup defaults */
 184         v9ses->afid = ~0;
 185         v9ses->debug = 0;
 186         v9ses->cache = CACHE_NONE;
 187 #ifdef CONFIG_9P_FSCACHE
 188         v9ses->cachetag = NULL;
 189 #endif
 190
 191         if (!opts)
 192                 return 0;
 193
 194         tmp_options = kstrdup(opts, GFP_KERNEL);
 195         if (!tmp_options) {
 196                 ret = -ENOMEM;
 197                 goto fail_option_alloc;
 198         }
 199         options = tmp_options;
 200
 201         while ((p = strsep(&options, ",")) != NULL) {
 202                 int token, r;
 203                 if (!*p)
 204                         continue;
 205                 token = match_token(p, tokens, args);
 206                 switch (token) {
 207                 case Opt_debug:
 208                         r = match_int(&args[0], &option);
 209                         if (r < 0) {
 210                                 p9_debug(P9_DEBUG_ERROR,
 211                                          "integer field, but no integer?\n");
 212                                 ret = r;
 213                                 continue;
 214                         }
 215                         v9ses->debug = option;
 216 #ifdef CONFIG_NET_9P_DEBUG
 217                         p9_debug_level = option;
 218 #endif
 219                         break;
 220
 221                 case Opt_dfltuid:
 222                         r = match_int(&args[0], &option);
 223                         if (r < 0) {
 224                                 p9_debug(P9_DEBUG_ERROR,
 225                                          "integer field, but no integer?\n");
 226                                 ret = r;
 227                                 continue;
 228                         }
 229                         v9ses->dfltuid = make_kuid(current_user_ns(), option);
 230                         if (!uid_valid(v9ses->dfltuid)) {
 231                                 p9_debug(P9_DEBUG_ERROR,
 232                                          "uid field, but not a uid?\n");
 233                                 ret = -EINVAL;
 234                                 continue;
 235                         }
 236                         break;
 237                 case Opt_dfltgid:
 238                         r = match_int(&args[0], &option);
 239                         if (r < 0) {
 240                                 p9_debug(P9_DEBUG_ERROR,
 241                                          "integer field, but no integer?\n");
 242                                 ret = r;
 243                                 continue;
 244                         }
 245                         v9ses->dfltgid = make_kgid(current_user_ns(), option);
 246                         if (!gid_valid(v9ses->dfltgid)) {
 247                                 p9_debug(P9_DEBUG_ERROR,
 248                                          "gid field, but not a gid?\n");
 249                                 ret = -EINVAL;
 250                                 continue;
 251                         }
 252                         break;
 253                 case Opt_afid:
 254                         r = match_int(&args[0], &option);
 255                         if (r < 0) {
 256                                 p9_debug(P9_DEBUG_ERROR,
 257                                          "integer field, but no integer?\n");
 258                                 ret = r;
 259                                 continue;
 260                         }
 261                         v9ses->afid = option;
 262                         break;
 263                 case Opt_uname:
 264                         kfree(v9ses->uname);
 265                         v9ses->uname = match_strdup(&args[0]);
 266                         if (!v9ses->uname) {
 267                                 ret = -ENOMEM;
 268                                 goto free_and_return;
 269                         }
 270                         break;
 271                 case Opt_remotename:
 272                         kfree(v9ses->aname);
 273                         v9ses->aname = match_strdup(&args[0]);
 274                         if (!v9ses->aname) {
 275                                 ret = -ENOMEM;
 276                                 goto free_and_return;
 277                         }
 278                         break;
 279                 case Opt_nodevmap:
 280                         v9ses->nodev = 1;
 281                         break;
 282                 case Opt_cache_loose:
 283                         v9ses->cache = CACHE_LOOSE;
 284                         break;
 285                 case Opt_fscache:
 286                         v9ses->cache = CACHE_FSCACHE;
 287                         break;
 288                 case Opt_mmap:
 289                         v9ses->cache = CACHE_MMAP;
 290                         break;
 291                 case Opt_cachetag:
 292 #ifdef CONFIG_9P_FSCACHE
 293                         kfree(v9ses->cachetag);
 294                         v9ses->cachetag = match_strdup(&args[0]);
 295                         if (!v9ses->cachetag) {
 296                                 ret = -ENOMEM;
 297                                 goto free_and_return;
 298                         }
 299 #endif
 300                         break;
 301                 case Opt_cache:
 302                         s = match_strdup(&args[0]);
 303                         if (!s) {
 304                                 ret = -ENOMEM;
 305                                 p9_debug(P9_DEBUG_ERROR,
 306                                          "problem allocating copy of cache arg\n");
 307                                 goto free_and_return;
 308                         }
 309                         ret = get_cache_mode(s);
 310                         if (ret == -EINVAL) {
 311                                 kfree(s);
 312                                 goto free_and_return;
 313                         }
 314
 315                         v9ses->cache = ret;
 316                         kfree(s);
 317                         break;
 318
 319                 case Opt_access:
 320                         s = match_strdup(&args[0]);
 321                         if (!s) {
 322                                 ret = -ENOMEM;
 323                                 p9_debug(P9_DEBUG_ERROR,
 324                                          "problem allocating copy of access arg\n");
 325                                 goto free_and_return;
 326                         }
 327
 328                         v9ses->flags &= ~V9FS_ACCESS_MASK;
 329                         if (strcmp(s, "user") == 0)
 330                                 v9ses->flags |= V9FS_ACCESS_USER;
 331                         else if (strcmp(s, "any") == 0)
 332                                 v9ses->flags |= V9FS_ACCESS_ANY;
 333                         else if (strcmp(s, "client") == 0) {
 334                                 v9ses->flags |= V9FS_ACCESS_CLIENT;
 335                         } else {
 336                                 uid_t uid;
 337                                 v9ses->flags |= V9FS_ACCESS_SINGLE;
 338                                 uid = simple_strtoul(s, &e, 10);
 339                                 if (*e != '\0') {
 340                                         ret = -EINVAL;
 341                                         pr_info("Unknown access argument %s\n",
 342                                                 s);
 343                                         kfree(s);
 344                                         goto free_and_return;
 345                                 }
 346                                 v9ses->uid = make_kuid(current_user_ns(), uid);
 347                                 if (!uid_valid(v9ses->uid)) {
 348                                         ret = -EINVAL;
 349                                         pr_info("Uknown uid %s\n", s);
 350                                         kfree(s);
 351                                         goto free_and_return;
 352                                 }
 353                         }
 354
 355                         kfree(s);
 356                         break;
 357
 358                 case Opt_posixacl:
 359 #ifdef CONFIG_9P_FS_POSIX_ACL
 360                         v9ses->flags |= V9FS_POSIX_ACL;
 361 #else
 362                         p9_debug(P9_DEBUG_ERROR,
 363                                  "Not defined CONFIG_9P_FS_POSIX_ACL. Ignoring posixacl option\n");
 364 #endif
 365                         break;
 366
 367                 default:
 368                         continue;
 369                 }
 370         }
 371
 372 free_and_return:
 373         kfree(tmp_options);
 374 fail_option_alloc:
 375         return ret;
 376 }
 377
 378 /**
 379  * v9fs_session_init - initialize session
 380  * @v9ses: session information structure
 381  * @dev_name: device being mounted
 382  * @data: options
 383  *
 384  */
 385
 386 struct p9_fid *v9fs_session_init(struct v9fs_session_info *v9ses,
 387                   const char *dev_name, char *data)
 388 {
 389         struct p9_fid *fid;
 390         int rc = -ENOMEM;
 391
 392         v9ses->uname = kstrdup(V9FS_DEFUSER, GFP_KERNEL);
 393         if (!v9ses->uname)
 394                 goto err_names;
 395
 396         v9ses->aname = kstrdup(V9FS_DEFANAME, GFP_KERNEL);
 397         if (!v9ses->aname)
 398                 goto err_names;
 399         init_rwsem(&v9ses->rename_sem);
 400
 401         v9ses->uid = INVALID_UID;
 402         v9ses->dfltuid = V9FS_DEFUID;
 403         v9ses->dfltgid = V9FS_DEFGID;
 404
 405         v9ses->clnt = p9_client_create(dev_name, data);
 406         if (IS_ERR(v9ses->clnt)) {
 407                 rc = PTR_ERR(v9ses->clnt);
 408                 p9_debug(P9_DEBUG_ERROR, "problem initializing 9p client\n");
 409                 goto err_names;
 410         }
 411
 412         v9ses->flags = V9FS_ACCESS_USER;
 413
 414         if (p9_is_proto_dotl(v9ses->clnt)) {
 415                 v9ses->flags = V9FS_ACCESS_CLIENT;
 416                 v9ses->flags |= V9FS_PROTO_2000L;
 417         } else if (p9_is_proto_dotu(v9ses->clnt)) {
 418                 v9ses->flags |= V9FS_PROTO_2000U;
 419         }
 420
 421         rc = v9fs_parse_options(v9ses, data);
 422         if (rc < 0)
 423                 goto err_clnt;
 424
 425         v9ses->maxdata = v9ses->clnt->msize - P9_IOHDRSZ;
 426
 427         if (!v9fs_proto_dotl(v9ses) &&
 428             ((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_CLIENT)) {
 429                 /*
 430                  * We support ACCESS_CLIENT only for dotl.
 431                  * Fall back to ACCESS_USER
 432                  */
 433                 v9ses->flags &= ~V9FS_ACCESS_MASK;
 434                 v9ses->flags |= V9FS_ACCESS_USER;
 435         }
 436         /*FIXME !! */
 437         /* for legacy mode, fall back to V9FS_ACCESS_ANY */
 438         if (!(v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses)) &&
 439                 ((v9ses->flags&V9FS_ACCESS_MASK) == V9FS_ACCESS_USER)) {
 440
 441                 v9ses->flags &= ~V9FS_ACCESS_MASK;
 442                 v9ses->flags |= V9FS_ACCESS_ANY;
 443                 v9ses->uid = INVALID_UID;
 444         }
 445         if (!v9fs_proto_dotl(v9ses) ||
 446                 !((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_CLIENT)) {
 447                 /*
 448                  * We support ACL checks on clinet only if the protocol is
 449                  * 9P2000.L and access is V9FS_ACCESS_CLIENT.
 450                  */
 451                 v9ses->flags &= ~V9FS_ACL_MASK;
 452         }
 453
 454         fid = p9_client_attach(v9ses->clnt, NULL, v9ses->uname, INVALID_UID,
 455                                                         v9ses->aname);
 456         if (IS_ERR(fid)) {
 457                 rc = PTR_ERR(fid);
 458                 p9_debug(P9_DEBUG_ERROR, "cannot attach\n");
 459                 goto err_clnt;
 460         }
 461
 462         if ((v9ses->flags & V9FS_ACCESS_MASK) == V9FS_ACCESS_SINGLE)
 463                 fid->uid = v9ses->uid;
 464         else
 465                 fid->uid = INVALID_UID;
 466
 467 #ifdef CONFIG_9P_FSCACHE
 468         /* register the session for caching */
 469         v9fs_cache_session_get_cookie(v9ses);
 470 #endif
 471         spin_lock(&v9fs_sessionlist_lock);
 472         list_add(&v9ses->slist, &v9fs_sessionlist);
 473         spin_unlock(&v9fs_sessionlist_lock);
 474
 475         return fid;
 476
 477 err_clnt:
 478 #ifdef CONFIG_9P_FSCACHE
 479         kfree(v9ses->cachetag);
 480 #endif
 481         p9_client_destroy(v9ses->clnt);
 482 err_names:
 483         kfree(v9ses->uname);
 484         kfree(v9ses->aname);
 485         return ERR_PTR(rc);
 486 }
 487
 488 /**
 489  * v9fs_session_close - shutdown a session
 490  * @v9ses: session information structure
 491  *
 492  */
 493
 494 void v9fs_session_close(struct v9fs_session_info *v9ses)
 495 {
 496         if (v9ses->clnt) {
 497                 p9_client_destroy(v9ses->clnt);
 498                 v9ses->clnt = NULL;
 499         }
 500
 501 #ifdef CONFIG_9P_FSCACHE
 502         if (v9ses->fscache) {
 503                 v9fs_cache_session_put_cookie(v9ses);
 504                 kfree(v9ses->cachetag);
 505         }
 506 #endif
 507         kfree(v9ses->uname);
 508         kfree(v9ses->aname);
 509
 510         spin_lock(&v9fs_sessionlist_lock);
 511         list_del(&v9ses->slist);
 512         spin_unlock(&v9fs_sessionlist_lock);
 513 }
 514
 515 /**
 516  * v9fs_session_cancel - terminate a session
 517  * @v9ses: session to terminate
 518  *
 519  * mark transport as disconnected and cancel all pending requests.
 520  */
 521
 522 void v9fs_session_cancel(struct v9fs_session_info *v9ses) {
 523         p9_debug(P9_DEBUG_ERROR, "cancel session %p\n", v9ses);
 524         p9_client_disconnect(v9ses->clnt);
 525 }
 526
 527 /**
 528  * v9fs_session_begin_cancel - Begin terminate of a session
 529  * @v9ses: session to terminate
 530  *
 531  * After this call we don't allow any request other than clunk.
 532  */
 533
 534 void v9fs_session_begin_cancel(struct v9fs_session_info *v9ses)
 535 {
 536         p9_debug(P9_DEBUG_ERROR, "begin cancel session %p\n", v9ses);
 537         p9_client_begin_disconnect(v9ses->clnt);
 538 }
 539
 540 extern int v9fs_error_init(void);
 541
 542 static struct kobject *v9fs_kobj;
 543
 544 #ifdef CONFIG_9P_FSCACHE
 545 /**
 546  * caches_show - list caches associated with a session
 547  *
 548  * Returns the size of buffer written.
 549  */
 550
 551 static ssize_t caches_show(struct kobject *kobj,
 552                            struct kobj_attribute *attr,
 553                            char *buf)
 554 {
 555         ssize_t n = 0, count = 0, limit = PAGE_SIZE;
 556         struct v9fs_session_info *v9ses;
 557
 558         spin_lock(&v9fs_sessionlist_lock);
 559         list_for_each_entry(v9ses, &v9fs_sessionlist, slist) {
 560                 if (v9ses->cachetag) {
 561                         n = snprintf(buf, limit, "%s\n", v9ses->cachetag);
 562                         if (n < 0) {
 563                                 count = n;
 564                                 break;
 565                         }
 566
 567                         count += n;
 568                         limit -= n;
 569                 }
 570         }
 571
 572         spin_unlock(&v9fs_sessionlist_lock);
 573         return count;
 574 }
 575
 576 static struct kobj_attribute v9fs_attr_cache = __ATTR_RO(caches);
 577 #endif /* CONFIG_9P_FSCACHE */
 578
 579 static struct attribute *v9fs_attrs[] = {
 580 #ifdef CONFIG_9P_FSCACHE
 581         &v9fs_attr_cache.attr,
 582 #endif
 583         NULL,
 584 };
 585
 586 static struct attribute_group v9fs_attr_group = {
 587         .attrs = v9fs_attrs,
 588 };
 589
 590 /**
 591  * v9fs_sysfs_init - Initialize the v9fs sysfs interface
 592  *
 593  */
 594
 595 static int __init v9fs_sysfs_init(void)
 596 {
 597         v9fs_kobj = kobject_create_and_add("9p", fs_kobj);
 598         if (!v9fs_kobj)
 599                 return -ENOMEM;
 600
 601         if (sysfs_create_group(v9fs_kobj, &v9fs_attr_group)) {
 602                 kobject_put(v9fs_kobj);
 603                 return -ENOMEM;
 604         }
 605
 606         return 0;
 607 }
 608
 609 /**
 610  * v9fs_sysfs_cleanup - Unregister the v9fs sysfs interface
 611  *
 612  */
 613
 614 static void v9fs_sysfs_cleanup(void)
 615 {
 616         sysfs_remove_group(v9fs_kobj, &v9fs_attr_group);
 617         kobject_put(v9fs_kobj);
 618 }
 619
 620 static void v9fs_inode_init_once(void *foo)
 621 {
 622         struct v9fs_inode *v9inode = (struct v9fs_inode *)foo;
 623 #ifdef CONFIG_9P_FSCACHE
 624         v9inode->fscache = NULL;
 625 #endif
 626         memset(&v9inode->qid, 0, sizeof(v9inode->qid));
 627         inode_init_once(&v9inode->vfs_inode);
 628 }
 629
 630 /**
 631  * v9fs_init_inode_cache - initialize a cache for 9P
 632  * Returns 0 on success.
 633  */
 634 static int v9fs_init_inode_cache(void)
 635 {
 636         v9fs_inode_cache = kmem_cache_create("v9fs_inode_cache",
 637                                           sizeof(struct v9fs_inode),
 638                                           0, (SLAB_RECLAIM_ACCOUNT|
 639                                               SLAB_MEM_SPREAD|SLAB_ACCOUNT),
 640                                           v9fs_inode_init_once);
 641         if (!v9fs_inode_cache)
 642                 return -ENOMEM;
 643
 644         return 0;
 645 }
 646
 647 /**
 648  * v9fs_destroy_inode_cache - destroy the cache of 9P inode
 649  *
 650  */
 651 static void v9fs_destroy_inode_cache(void)
 652 {
 653         /*
 654          * Make sure all delayed rcu free inodes are flushed before we
 655          * destroy cache.
 656          */
 657         rcu_barrier();
 658         kmem_cache_destroy(v9fs_inode_cache);
 659 }
 660
 661 static int v9fs_cache_register(void)
 662 {
 663         int ret;
 664         ret = v9fs_init_inode_cache();
 665         if (ret < 0)
 666                 return ret;
 667 #ifdef CONFIG_9P_FSCACHE
 668         ret = fscache_register_netfs(&v9fs_cache_netfs);
 669         if (ret < 0)
 670                 v9fs_destroy_inode_cache();
 671 #endif
 672         return ret;
 673 }
 674
 675 static void v9fs_cache_unregister(void)
 676 {
 677         v9fs_destroy_inode_cache();
 678 #ifdef CONFIG_9P_FSCACHE
 679         fscache_unregister_netfs(&v9fs_cache_netfs);
 680 #endif
 681 }
 682
 683 /**
 684  * init_v9fs - Initialize module
 685  *
 686  */
 687
 688 static int __init init_v9fs(void)
 689 {
 690         int err;
 691         pr_info("Installing v9fs 9p2000 file system support\n");
 692         /* TODO: Setup list of registered trasnport modules */
 693
 694         err = v9fs_cache_register();
 695         if (err < 0) {
 696                 pr_err("Failed to register v9fs for caching\n");
 697                 return err;
 698         }
 699
 700         err = v9fs_sysfs_init();
 701         if (err < 0) {
 702                 pr_err("Failed to register with sysfs\n");
 703                 goto out_cache;
 704         }
 705         err = register_filesystem(&v9fs_fs_type);
 706         if (err < 0) {
 707                 pr_err("Failed to register filesystem\n");
 708                 goto out_sysfs_cleanup;
 709         }
 710
 711         return 0;
 712
 713 out_sysfs_cleanup:
 714         v9fs_sysfs_cleanup();
 715
 716 out_cache:
 717         v9fs_cache_unregister();
 718
 719         return err;
 720 }
 721
 722 /**
 723  * exit_v9fs - shutdown module
 724  *
 725  */
 726
 727 static void __exit exit_v9fs(void)
 728 {
 729         v9fs_sysfs_cleanup();
 730         v9fs_cache_unregister();
 731         unregister_filesystem(&v9fs_fs_type);
 732 }
 733
 734 module_init(init_v9fs)
 735 module_exit(exit_v9fs)
 736
 737 MODULE_AUTHOR("Latchesar Ionkov <lucho@ionkov.net>");
 738 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");
 739 MODULE_AUTHOR("Ron Minnich <rminnich@lanl.gov>");
 740 MODULE_LICENSE("GPL");