net/sunrpc/rpc_pipe.c

   1 /*
   2  * net/sunrpc/rpc_pipe.c
   3  *
   4  * Userland/kernel interface for rpcauth_gss.
   5  * Code shamelessly plagiarized from fs/nfsd/nfsctl.c
   6  * and fs/sysfs/inode.c
   7  *
   8  * Copyright (c) 2002, Trond Myklebust <trond.myklebust@fys.uio.no>
   9  *
  10  */
  11 #include <linux/module.h>
  12 #include <linux/slab.h>
  13 #include <linux/string.h>
  14 #include <linux/pagemap.h>
  15 #include <linux/mount.h>
  16 #include <linux/namei.h>
  17 #include <linux/fsnotify.h>
  18 #include <linux/kernel.h>
  19
  20 #include <asm/ioctls.h>
  21 #include <linux/fs.h>
  22 #include <linux/poll.h>
  23 #include <linux/wait.h>
  24 #include <linux/seq_file.h>
  25
  26 #include <linux/sunrpc/clnt.h>
  27 #include <linux/workqueue.h>
  28 #include <linux/sunrpc/rpc_pipe_fs.h>
  29
  30 static struct vfsmount *rpc_mount __read_mostly;
  31 static int rpc_mount_count;
  32
  33 static struct file_system_type rpc_pipe_fs_type;
  34
  35
  36 static struct kmem_cache *rpc_inode_cachep __read_mostly;
  37
  38 #define RPC_UPCALL_TIMEOUT (30*HZ)
  39
  40 static void rpc_purge_list(struct rpc_inode *rpci, struct list_head *head,
  41                 void (*destroy_msg)(struct rpc_pipe_msg *), int err)
  42 {
  43         struct rpc_pipe_msg *msg;
  44
  45         if (list_empty(head))
  46                 return;
  47         do {
  48                 msg = list_entry(head->next, struct rpc_pipe_msg, list);
  49                 list_del(&msg->list);
  50                 msg->errno = err;
  51                 destroy_msg(msg);
  52         } while (!list_empty(head));
  53         wake_up(&rpci->waitq);
  54 }
  55
  56 static void
  57 rpc_timeout_upcall_queue(struct work_struct *work)
  58 {
  59         LIST_HEAD(free_list);
  60         struct rpc_inode *rpci =
  61                 container_of(work, struct rpc_inode, queue_timeout.work);
  62         struct inode *inode = &rpci->vfs_inode;
  63         void (*destroy_msg)(struct rpc_pipe_msg *);
  64
  65         spin_lock(&inode->i_lock);
  66         if (rpci->ops == NULL) {
  67                 spin_unlock(&inode->i_lock);
  68                 return;
  69         }
  70         destroy_msg = rpci->ops->destroy_msg;
  71         if (rpci->nreaders == 0) {
  72                 list_splice_init(&rpci->pipe, &free_list);
  73                 rpci->pipelen = 0;
  74         }
  75         spin_unlock(&inode->i_lock);
  76         rpc_purge_list(rpci, &free_list, destroy_msg, -ETIMEDOUT);
  77 }
  78
  79 /**
  80  * rpc_queue_upcall
  81  * @inode: inode of upcall pipe on which to queue given message
  82  * @msg: message to queue
  83  *
  84  * Call with an @inode created by rpc_mkpipe() to queue an upcall.
  85  * A userspace process may then later read the upcall by performing a
  86  * read on an open file for this inode.  It is up to the caller to
  87  * initialize the fields of @msg (other than @msg->list) appropriately.
  88  */
  89 int
  90 rpc_queue_upcall(struct inode *inode, struct rpc_pipe_msg *msg)
  91 {
  92         struct rpc_inode *rpci = RPC_I(inode);
  93         int res = -EPIPE;
  94
  95         spin_lock(&inode->i_lock);
  96         if (rpci->ops == NULL)
  97                 goto out;
  98         if (rpci->nreaders) {
  99                 list_add_tail(&msg->list, &rpci->pipe);
 100                 rpci->pipelen += msg->len;
 101                 res = 0;
 102         } else if (rpci->flags & RPC_PIPE_WAIT_FOR_OPEN) {
 103                 if (list_empty(&rpci->pipe))
 104                         queue_delayed_work(rpciod_workqueue,
 105                                         &rpci->queue_timeout,
 106                                         RPC_UPCALL_TIMEOUT);
 107                 list_add_tail(&msg->list, &rpci->pipe);
 108                 rpci->pipelen += msg->len;
 109                 res = 0;
 110         }
 111 out:
 112         spin_unlock(&inode->i_lock);
 113         wake_up(&rpci->waitq);
 114         return res;
 115 }
 116 EXPORT_SYMBOL_GPL(rpc_queue_upcall);
 117
 118 static inline void
 119 rpc_inode_setowner(struct inode *inode, void *private)
 120 {
 121         RPC_I(inode)->private = private;
 122 }
 123
 124 static void
 125 rpc_close_pipes(struct inode *inode)
 126 {
 127         struct rpc_inode *rpci = RPC_I(inode);
 128         struct rpc_pipe_ops *ops;
 129         int need_release;
 130
 131         mutex_lock(&inode->i_mutex);
 132         ops = rpci->ops;
 133         if (ops != NULL) {
 134                 LIST_HEAD(free_list);
 135                 spin_lock(&inode->i_lock);
 136                 need_release = rpci->nreaders != 0 || rpci->nwriters != 0;
 137                 rpci->nreaders = 0;
 138                 list_splice_init(&rpci->in_upcall, &free_list);
 139                 list_splice_init(&rpci->pipe, &free_list);
 140                 rpci->pipelen = 0;
 141                 rpci->ops = NULL;
 142                 spin_unlock(&inode->i_lock);
 143                 rpc_purge_list(rpci, &free_list, ops->destroy_msg, -EPIPE);
 144                 rpci->nwriters = 0;
 145                 if (need_release && ops->release_pipe)
 146                         ops->release_pipe(inode);
 147                 cancel_delayed_work_sync(&rpci->queue_timeout);
 148         }
 149         rpc_inode_setowner(inode, NULL);
 150         mutex_unlock(&inode->i_mutex);
 151 }
 152
 153 static struct inode *
 154 rpc_alloc_inode(struct super_block *sb)
 155 {
 156         struct rpc_inode *rpci;
 157         rpci = (struct rpc_inode *)kmem_cache_alloc(rpc_inode_cachep, GFP_KERNEL);
 158         if (!rpci)
 159                 return NULL;
 160         return &rpci->vfs_inode;
 161 }
 162
 163 static void
 164 rpc_destroy_inode(struct inode *inode)
 165 {
 166         kmem_cache_free(rpc_inode_cachep, RPC_I(inode));
 167 }
 168
 169 static int
 170 rpc_pipe_open(struct inode *inode, struct file *filp)
 171 {
 172         struct rpc_inode *rpci = RPC_I(inode);
 173         int first_open;
 174         int res = -ENXIO;
 175
 176         mutex_lock(&inode->i_mutex);
 177         if (rpci->ops == NULL)
 178                 goto out;
 179         first_open = rpci->nreaders == 0 && rpci->nwriters == 0;
 180         if (first_open && rpci->ops->open_pipe) {
 181                 res = rpci->ops->open_pipe(inode);
 182                 if (res)
 183                         goto out;
 184         }
 185         if (filp->f_mode & FMODE_READ)
 186                 rpci->nreaders++;
 187         if (filp->f_mode & FMODE_WRITE)
 188                 rpci->nwriters++;
 189         res = 0;
 190 out:
 191         mutex_unlock(&inode->i_mutex);
 192         return res;
 193 }
 194
 195 static int
 196 rpc_pipe_release(struct inode *inode, struct file *filp)
 197 {
 198         struct rpc_inode *rpci = RPC_I(inode);
 199         struct rpc_pipe_msg *msg;
 200         int last_close;
 201
 202         mutex_lock(&inode->i_mutex);
 203         if (rpci->ops == NULL)
 204                 goto out;
 205         msg = (struct rpc_pipe_msg *)filp->private_data;
 206         if (msg != NULL) {
 207                 spin_lock(&inode->i_lock);
 208                 msg->errno = -EAGAIN;
 209                 list_del(&msg->list);
 210                 spin_unlock(&inode->i_lock);
 211                 rpci->ops->destroy_msg(msg);
 212         }
 213         if (filp->f_mode & FMODE_WRITE)
 214                 rpci->nwriters --;
 215         if (filp->f_mode & FMODE_READ) {
 216                 rpci->nreaders --;
 217                 if (rpci->nreaders == 0) {
 218                         LIST_HEAD(free_list);
 219                         spin_lock(&inode->i_lock);
 220                         list_splice_init(&rpci->pipe, &free_list);
 221                         rpci->pipelen = 0;
 222                         spin_unlock(&inode->i_lock);
 223                         rpc_purge_list(rpci, &free_list,
 224                                         rpci->ops->destroy_msg, -EAGAIN);
 225                 }
 226         }
 227         last_close = rpci->nwriters == 0 && rpci->nreaders == 0;
 228         if (last_close && rpci->ops->release_pipe)
 229                 rpci->ops->release_pipe(inode);
 230 out:
 231         mutex_unlock(&inode->i_mutex);
 232         return 0;
 233 }
 234
 235 static ssize_t
 236 rpc_pipe_read(struct file *filp, char __user *buf, size_t len, loff_t *offset)
 237 {
 238         struct inode *inode = filp->f_path.dentry->d_inode;
 239         struct rpc_inode *rpci = RPC_I(inode);
 240         struct rpc_pipe_msg *msg;
 241         int res = 0;
 242
 243         mutex_lock(&inode->i_mutex);
 244         if (rpci->ops == NULL) {
 245                 res = -EPIPE;
 246                 goto out_unlock;
 247         }
 248         msg = filp->private_data;
 249         if (msg == NULL) {
 250                 spin_lock(&inode->i_lock);
 251                 if (!list_empty(&rpci->pipe)) {
 252                         msg = list_entry(rpci->pipe.next,
 253                                         struct rpc_pipe_msg,
 254                                         list);
 255                         list_move(&msg->list, &rpci->in_upcall);
 256                         rpci->pipelen -= msg->len;
 257                         filp->private_data = msg;
 258                         msg->copied = 0;
 259                 }
 260                 spin_unlock(&inode->i_lock);
 261                 if (msg == NULL)
 262                         goto out_unlock;
 263         }
 264         /* NOTE: it is up to the callback to update msg->copied */
 265         res = rpci->ops->upcall(filp, msg, buf, len);
 266         if (res < 0 || msg->len == msg->copied) {
 267                 filp->private_data = NULL;
 268                 spin_lock(&inode->i_lock);
 269                 list_del(&msg->list);
 270                 spin_unlock(&inode->i_lock);
 271                 rpci->ops->destroy_msg(msg);
 272         }
 273 out_unlock:
 274         mutex_unlock(&inode->i_mutex);
 275         return res;
 276 }
 277
 278 static ssize_t
 279 rpc_pipe_write(struct file *filp, const char __user *buf, size_t len, loff_t *offset)
 280 {
 281         struct inode *inode = filp->f_path.dentry->d_inode;
 282         struct rpc_inode *rpci = RPC_I(inode);
 283         int res;
 284
 285         mutex_lock(&inode->i_mutex);
 286         res = -EPIPE;
 287         if (rpci->ops != NULL)
 288                 res = rpci->ops->downcall(filp, buf, len);
 289         mutex_unlock(&inode->i_mutex);
 290         return res;
 291 }
 292
 293 static unsigned int
 294 rpc_pipe_poll(struct file *filp, struct poll_table_struct *wait)
 295 {
 296         struct rpc_inode *rpci;
 297         unsigned int mask = 0;
 298
 299         rpci = RPC_I(filp->f_path.dentry->d_inode);
 300         poll_wait(filp, &rpci->waitq, wait);
 301
 302         mask = POLLOUT | POLLWRNORM;
 303         if (rpci->ops == NULL)
 304                 mask |= POLLERR | POLLHUP;
 305         if (filp->private_data || !list_empty(&rpci->pipe))
 306                 mask |= POLLIN | POLLRDNORM;
 307         return mask;
 308 }
 309
 310 static int
 311 rpc_pipe_ioctl(struct inode *ino, struct file *filp,
 312                 unsigned int cmd, unsigned long arg)
 313 {
 314         struct rpc_inode *rpci = RPC_I(filp->f_path.dentry->d_inode);
 315         int len;
 316
 317         switch (cmd) {
 318         case FIONREAD:
 319                 if (rpci->ops == NULL)
 320                         return -EPIPE;
 321                 len = rpci->pipelen;
 322                 if (filp->private_data) {
 323                         struct rpc_pipe_msg *msg;
 324                         msg = (struct rpc_pipe_msg *)filp->private_data;
 325                         len += msg->len - msg->copied;
 326                 }
 327                 return put_user(len, (int __user *)arg);
 328         default:
 329                 return -EINVAL;
 330         }
 331 }
 332
 333 static const struct file_operations rpc_pipe_fops = {
 334         .owner          = THIS_MODULE,
 335         .llseek         = no_llseek,
 336         .read           = rpc_pipe_read,
 337         .write          = rpc_pipe_write,
 338         .poll           = rpc_pipe_poll,
 339         .ioctl          = rpc_pipe_ioctl,
 340         .open           = rpc_pipe_open,
 341         .release        = rpc_pipe_release,
 342 };
 343
 344 static int
 345 rpc_show_info(struct seq_file *m, void *v)
 346 {
 347         struct rpc_clnt *clnt = m->private;
 348
 349         seq_printf(m, "RPC server: %s\n", clnt->cl_server);
 350         seq_printf(m, "service: %s (%d) version %d\n", clnt->cl_protname,
 351                         clnt->cl_prog, clnt->cl_vers);
 352         seq_printf(m, "address: %s\n", rpc_peeraddr2str(clnt, RPC_DISPLAY_ADDR));
 353         seq_printf(m, "protocol: %s\n", rpc_peeraddr2str(clnt, RPC_DISPLAY_PROTO));
 354         seq_printf(m, "port: %s\n", rpc_peeraddr2str(clnt, RPC_DISPLAY_PORT));
 355         return 0;
 356 }
 357
 358 static int
 359 rpc_info_open(struct inode *inode, struct file *file)
 360 {
 361         struct rpc_clnt *clnt;
 362         int ret = single_open(file, rpc_show_info, NULL);
 363
 364         if (!ret) {
 365                 struct seq_file *m = file->private_data;
 366                 mutex_lock(&inode->i_mutex);
 367                 clnt = RPC_I(inode)->private;
 368                 if (clnt) {
 369                         kref_get(&clnt->cl_kref);
 370                         m->private = clnt;
 371                 } else {
 372                         single_release(inode, file);
 373                         ret = -EINVAL;
 374                 }
 375                 mutex_unlock(&inode->i_mutex);
 376         }
 377         return ret;
 378 }
 379
 380 static int
 381 rpc_info_release(struct inode *inode, struct file *file)
 382 {
 383         struct seq_file *m = file->private_data;
 384         struct rpc_clnt *clnt = (struct rpc_clnt *)m->private;
 385
 386         if (clnt)
 387                 rpc_release_client(clnt);
 388         return single_release(inode, file);
 389 }
 390
 391 static const struct file_operations rpc_info_operations = {
 392         .owner          = THIS_MODULE,
 393         .open           = rpc_info_open,
 394         .read           = seq_read,
 395         .llseek         = seq_lseek,
 396         .release        = rpc_info_release,
 397 };
 398
 399
 400 /*
 401  * We have a single directory with 1 node in it.
 402  */
 403 enum {
 404         RPCAUTH_Root = 1,
 405         RPCAUTH_lockd,
 406         RPCAUTH_mount,
 407         RPCAUTH_nfs,
 408         RPCAUTH_portmap,
 409         RPCAUTH_statd,
 410         RPCAUTH_nfsd4_cb,
 411         RPCAUTH_RootEOF
 412 };
 413
 414 /*
 415  * Description of fs contents.
 416  */
 417 struct rpc_filelist {
 418         char *name;
 419         const struct file_operations *i_fop;
 420         int mode;
 421 };
 422
 423 static struct rpc_filelist files[] = {
 424         [RPCAUTH_lockd] = {
 425                 .name = "lockd",
 426                 .mode = S_IFDIR | S_IRUGO | S_IXUGO,
 427         },
 428         [RPCAUTH_mount] = {
 429                 .name = "mount",
 430                 .mode = S_IFDIR | S_IRUGO | S_IXUGO,
 431         },
 432         [RPCAUTH_nfs] = {
 433                 .name = "nfs",
 434                 .mode = S_IFDIR | S_IRUGO | S_IXUGO,
 435         },
 436         [RPCAUTH_portmap] = {
 437                 .name = "portmap",
 438                 .mode = S_IFDIR | S_IRUGO | S_IXUGO,
 439         },
 440         [RPCAUTH_statd] = {
 441                 .name = "statd",
 442                 .mode = S_IFDIR | S_IRUGO | S_IXUGO,
 443         },
 444         [RPCAUTH_nfsd4_cb] = {
 445                 .name = "nfsd4_cb",
 446                 .mode = S_IFDIR | S_IRUGO | S_IXUGO,
 447         },
 448 };
 449
 450 enum {
 451         RPCAUTH_info = 2,
 452         RPCAUTH_EOF
 453 };
 454
 455 static struct rpc_filelist authfiles[] = {
 456         [RPCAUTH_info] = {
 457                 .name = "info",
 458                 .i_fop = &rpc_info_operations,
 459                 .mode = S_IFREG | S_IRUSR,
 460         },
 461 };
 462
 463 struct vfsmount *rpc_get_mount(void)
 464 {
 465         int err;
 466
 467         err = simple_pin_fs(&rpc_pipe_fs_type, &rpc_mount, &rpc_mount_count);
 468         if (err != 0)
 469                 return ERR_PTR(err);
 470         return rpc_mount;
 471 }
 472
 473 void rpc_put_mount(void)
 474 {
 475         simple_release_fs(&rpc_mount, &rpc_mount_count);
 476 }
 477
 478 static int rpc_delete_dentry(struct dentry *dentry)
 479 {
 480         return 1;
 481 }
 482
 483 static struct dentry_operations rpc_dentry_operations = {
 484         .d_delete = rpc_delete_dentry,
 485 };
 486
 487 static int
 488 rpc_lookup_parent(char *path, struct nameidata *nd)
 489 {
 490         struct vfsmount *mnt;
 491
 492         if (path[0] == '\0')
 493                 return -ENOENT;
 494
 495         mnt = rpc_get_mount();
 496         if (IS_ERR(mnt)) {
 497                 printk(KERN_WARNING "%s: %s failed to mount "
 498                                "pseudofilesystem \n", __FILE__, __func__);
 499                 return PTR_ERR(mnt);
 500         }
 501
 502         if (vfs_path_lookup(mnt->mnt_root, mnt, path, LOOKUP_PARENT, nd)) {
 503                 printk(KERN_WARNING "%s: %s failed to find path %s\n",
 504                                 __FILE__, __func__, path);
 505                 rpc_put_mount();
 506                 return -ENOENT;
 507         }
 508         return 0;
 509 }
 510
 511 static void
 512 rpc_release_path(struct nameidata *nd)
 513 {
 514         path_put(&nd->path);
 515         rpc_put_mount();
 516 }
 517
 518 static struct inode *
 519 rpc_get_inode(struct super_block *sb, int mode)
 520 {
 521         struct inode *inode = new_inode(sb);
 522         if (!inode)
 523                 return NULL;
 524         inode->i_mode = mode;
 525         inode->i_uid = inode->i_gid = 0;
 526         inode->i_blocks = 0;
 527         inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 528         switch(mode & S_IFMT) {
 529                 case S_IFDIR:
 530                         inode->i_fop = &simple_dir_operations;
 531                         inode->i_op = &simple_dir_inode_operations;
 532                         inc_nlink(inode);
 533                 default:
 534                         break;
 535         }
 536         return inode;
 537 }
 538
 539 /*
 540  * FIXME: This probably has races.
 541  */
 542 static void rpc_depopulate(struct dentry *parent,
 543                            unsigned long start, unsigned long eof)
 544 {
 545         struct inode *dir = parent->d_inode;
 546         struct list_head *pos, *next;
 547         struct dentry *dentry, *dvec[10];
 548         int n = 0;
 549
 550         mutex_lock_nested(&dir->i_mutex, I_MUTEX_CHILD);
 551 repeat:
 552         spin_lock(&dcache_lock);
 553         list_for_each_safe(pos, next, &parent->d_subdirs) {
 554                 dentry = list_entry(pos, struct dentry, d_u.d_child);
 555                 if (!dentry->d_inode ||
 556                                 dentry->d_inode->i_ino < start ||
 557                                 dentry->d_inode->i_ino >= eof)
 558                         continue;
 559                 spin_lock(&dentry->d_lock);
 560                 if (!d_unhashed(dentry)) {
 561                         dget_locked(dentry);
 562                         __d_drop(dentry);
 563                         spin_unlock(&dentry->d_lock);
 564                         dvec[n++] = dentry;
 565                         if (n == ARRAY_SIZE(dvec))
 566                                 break;
 567                 } else
 568                         spin_unlock(&dentry->d_lock);
 569         }
 570         spin_unlock(&dcache_lock);
 571         if (n) {
 572                 do {
 573                         dentry = dvec[--n];
 574                         if (S_ISREG(dentry->d_inode->i_mode))
 575                                 simple_unlink(dir, dentry);
 576                         else if (S_ISDIR(dentry->d_inode->i_mode))
 577                                 simple_rmdir(dir, dentry);
 578                         d_delete(dentry);
 579                         dput(dentry);
 580                 } while (n);
 581                 goto repeat;
 582         }
 583         mutex_unlock(&dir->i_mutex);
 584 }
 585
 586 static int
 587 rpc_populate(struct dentry *parent,
 588                 struct rpc_filelist *files,
 589                 int start, int eof)
 590 {
 591         struct inode *inode, *dir = parent->d_inode;
 592         void *private = RPC_I(dir)->private;
 593         struct dentry *dentry;
 594         int mode, i;
 595
 596         mutex_lock(&dir->i_mutex);
 597         for (i = start; i < eof; i++) {
 598                 dentry = d_alloc_name(parent, files[i].name);
 599                 if (!dentry)
 600                         goto out_bad;
 601                 dentry->d_op = &rpc_dentry_operations;
 602                 mode = files[i].mode;
 603                 inode = rpc_get_inode(dir->i_sb, mode);
 604                 if (!inode) {
 605                         dput(dentry);
 606                         goto out_bad;
 607                 }
 608                 inode->i_ino = i;
 609                 if (files[i].i_fop)
 610                         inode->i_fop = files[i].i_fop;
 611                 if (private)
 612                         rpc_inode_setowner(inode, private);
 613                 if (S_ISDIR(mode))
 614                         inc_nlink(dir);
 615                 d_add(dentry, inode);
 616                 fsnotify_create(dir, dentry);
 617         }
 618         mutex_unlock(&dir->i_mutex);
 619         return 0;
 620 out_bad:
 621         mutex_unlock(&dir->i_mutex);
 622         printk(KERN_WARNING "%s: %s failed to populate directory %s\n",
 623                         __FILE__, __func__, parent->d_name.name);
 624         return -ENOMEM;
 625 }
 626
 627 static int
 628 __rpc_mkdir(struct inode *dir, struct dentry *dentry)
 629 {
 630         struct inode *inode;
 631
 632         inode = rpc_get_inode(dir->i_sb, S_IFDIR | S_IRUGO | S_IXUGO);
 633         if (!inode)
 634                 goto out_err;
 635         inode->i_ino = iunique(dir->i_sb, 100);
 636         d_instantiate(dentry, inode);
 637         inc_nlink(dir);
 638         fsnotify_mkdir(dir, dentry);
 639         return 0;
 640 out_err:
 641         printk(KERN_WARNING "%s: %s failed to allocate inode for dentry %s\n",
 642                         __FILE__, __func__, dentry->d_name.name);
 643         return -ENOMEM;
 644 }
 645
 646 static int
 647 __rpc_rmdir(struct inode *dir, struct dentry *dentry)
 648 {
 649         int error;
 650         error = simple_rmdir(dir, dentry);
 651         if (!error)
 652                 d_delete(dentry);
 653         return error;
 654 }
 655
 656 static struct dentry *
 657 rpc_lookup_create(struct dentry *parent, const char *name, int len, int exclusive)
 658 {
 659         struct inode *dir = parent->d_inode;
 660         struct dentry *dentry;
 661
 662         mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
 663         dentry = lookup_one_len(name, parent, len);
 664         if (IS_ERR(dentry))
 665                 goto out_err;
 666         if (!dentry->d_inode)
 667                 dentry->d_op = &rpc_dentry_operations;
 668         else if (exclusive) {
 669                 dput(dentry);
 670                 dentry = ERR_PTR(-EEXIST);
 671                 goto out_err;
 672         }
 673         return dentry;
 674 out_err:
 675         mutex_unlock(&dir->i_mutex);
 676         return dentry;
 677 }
 678
 679 static struct dentry *
 680 rpc_lookup_negative(char *path, struct nameidata *nd)
 681 {
 682         struct dentry *dentry;
 683         int error;
 684
 685         if ((error = rpc_lookup_parent(path, nd)) != 0)
 686                 return ERR_PTR(error);
 687         dentry = rpc_lookup_create(nd->path.dentry, nd->last.name, nd->last.len,
 688                                    1);
 689         if (IS_ERR(dentry))
 690                 rpc_release_path(nd);
 691         return dentry;
 692 }
 693
 694 /**
 695  * rpc_mkdir - Create a new directory in rpc_pipefs
 696  * @path: path from the rpc_pipefs root to the new directory
 697  * @rpc_client: rpc client to associate with this directory
 698  *
 699  * This creates a directory at the given @path associated with
 700  * @rpc_clnt, which will contain a file named "info" with some basic
 701  * information about the client, together with any "pipes" that may
 702  * later be created using rpc_mkpipe().
 703  */
 704 struct dentry *
 705 rpc_mkdir(char *path, struct rpc_clnt *rpc_client)
 706 {
 707         struct nameidata nd;
 708         struct dentry *dentry;
 709         struct inode *dir;
 710         int error;
 711
 712         dentry = rpc_lookup_negative(path, &nd);
 713         if (IS_ERR(dentry))
 714                 return dentry;
 715         dir = nd.path.dentry->d_inode;
 716         if ((error = __rpc_mkdir(dir, dentry)) != 0)
 717                 goto err_dput;
 718         RPC_I(dentry->d_inode)->private = rpc_client;
 719         error = rpc_populate(dentry, authfiles,
 720                         RPCAUTH_info, RPCAUTH_EOF);
 721         if (error)
 722                 goto err_depopulate;
 723         dget(dentry);
 724 out:
 725         mutex_unlock(&dir->i_mutex);
 726         rpc_release_path(&nd);
 727         return dentry;
 728 err_depopulate:
 729         rpc_depopulate(dentry, RPCAUTH_info, RPCAUTH_EOF);
 730         __rpc_rmdir(dir, dentry);
 731 err_dput:
 732         dput(dentry);
 733         printk(KERN_WARNING "%s: %s() failed to create directory %s (errno = %d)\n",
 734                         __FILE__, __func__, path, error);
 735         dentry = ERR_PTR(error);
 736         goto out;
 737 }
 738
 739 /**
 740  * rpc_rmdir - Remove a directory created with rpc_mkdir()
 741  * @dentry: directory to remove
 742  */
 743 int
 744 rpc_rmdir(struct dentry *dentry)
 745 {
 746         struct dentry *parent;
 747         struct inode *dir;
 748         int error;
 749
 750         parent = dget_parent(dentry);
 751         dir = parent->d_inode;
 752         mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
 753         rpc_depopulate(dentry, RPCAUTH_info, RPCAUTH_EOF);
 754         error = __rpc_rmdir(dir, dentry);
 755         dput(dentry);
 756         mutex_unlock(&dir->i_mutex);
 757         dput(parent);
 758         return error;
 759 }
 760
 761 /**
 762  * rpc_mkpipe - make an rpc_pipefs file for kernel<->userspace communication
 763  * @parent: dentry of directory to create new "pipe" in
 764  * @name: name of pipe
 765  * @private: private data to associate with the pipe, for the caller's use
 766  * @ops: operations defining the behavior of the pipe: upcall, downcall,
 767  *      release_pipe, open_pipe, and destroy_msg.
 768  * @flags: rpc_inode flags
 769  *
 770  * Data is made available for userspace to read by calls to
 771  * rpc_queue_upcall().  The actual reads will result in calls to
 772  * @ops->upcall, which will be called with the file pointer,
 773  * message, and userspace buffer to copy to.
 774  *
 775  * Writes can come at any time, and do not necessarily have to be
 776  * responses to upcalls.  They will result in calls to @msg->downcall.
 777  *
 778  * The @private argument passed here will be available to all these methods
 779  * from the file pointer, via RPC_I(file->f_dentry->d_inode)->private.
 780  */
 781 struct dentry *
 782 rpc_mkpipe(struct dentry *parent, const char *name, void *private, struct rpc_pipe_ops *ops, int flags)
 783 {
 784         struct dentry *dentry;
 785         struct inode *dir, *inode;
 786         struct rpc_inode *rpci;
 787
 788         dentry = rpc_lookup_create(parent, name, strlen(name), 0);
 789         if (IS_ERR(dentry))
 790                 return dentry;
 791         dir = parent->d_inode;
 792         if (dentry->d_inode) {
 793                 rpci = RPC_I(dentry->d_inode);
 794                 if (rpci->private != private ||
 795                                 rpci->ops != ops ||
 796                                 rpci->flags != flags) {
 797                         dput (dentry);
 798                         dentry = ERR_PTR(-EBUSY);
 799                 }
 800                 rpci->nkern_readwriters++;
 801                 goto out;
 802         }
 803         inode = rpc_get_inode(dir->i_sb, S_IFIFO | S_IRUSR | S_IWUSR);
 804         if (!inode)
 805                 goto err_dput;
 806         inode->i_ino = iunique(dir->i_sb, 100);
 807         inode->i_fop = &rpc_pipe_fops;
 808         d_instantiate(dentry, inode);
 809         rpci = RPC_I(inode);
 810         rpci->private = private;
 811         rpci->flags = flags;
 812         rpci->ops = ops;
 813         rpci->nkern_readwriters = 1;
 814         fsnotify_create(dir, dentry);
 815         dget(dentry);
 816 out:
 817         mutex_unlock(&dir->i_mutex);
 818         return dentry;
 819 err_dput:
 820         dput(dentry);
 821         dentry = ERR_PTR(-ENOMEM);
 822         printk(KERN_WARNING "%s: %s() failed to create pipe %s/%s (errno = %d)\n",
 823                         __FILE__, __func__, parent->d_name.name, name,
 824                         -ENOMEM);
 825         goto out;
 826 }
 827 EXPORT_SYMBOL_GPL(rpc_mkpipe);
 828
 829 /**
 830  * rpc_unlink - remove a pipe
 831  * @dentry: dentry for the pipe, as returned from rpc_mkpipe
 832  *
 833  * After this call, lookups will no longer find the pipe, and any
 834  * attempts to read or write using preexisting opens of the pipe will
 835  * return -EPIPE.
 836  */
 837 int
 838 rpc_unlink(struct dentry *dentry)
 839 {
 840         struct dentry *parent;
 841         struct inode *dir;
 842         int error = 0;
 843
 844         parent = dget_parent(dentry);
 845         dir = parent->d_inode;
 846         mutex_lock_nested(&dir->i_mutex, I_MUTEX_PARENT);
 847         if (--RPC_I(dentry->d_inode)->nkern_readwriters == 0) {
 848                 rpc_close_pipes(dentry->d_inode);
 849                 error = simple_unlink(dir, dentry);
 850                 if (!error)
 851                         d_delete(dentry);
 852         }
 853         dput(dentry);
 854         mutex_unlock(&dir->i_mutex);
 855         dput(parent);
 856         return error;
 857 }
 858 EXPORT_SYMBOL_GPL(rpc_unlink);
 859
 860 /*
 861  * populate the filesystem
 862  */
 863 static struct super_operations s_ops = {
 864         .alloc_inode    = rpc_alloc_inode,
 865         .destroy_inode  = rpc_destroy_inode,
 866         .statfs         = simple_statfs,
 867 };
 868
 869 #define RPCAUTH_GSSMAGIC 0x67596969
 870
 871 static int
 872 rpc_fill_super(struct super_block *sb, void *data, int silent)
 873 {
 874         struct inode *inode;
 875         struct dentry *root;
 876
 877         sb->s_blocksize = PAGE_CACHE_SIZE;
 878         sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
 879         sb->s_magic = RPCAUTH_GSSMAGIC;
 880         sb->s_op = &s_ops;
 881         sb->s_time_gran = 1;
 882
 883         inode = rpc_get_inode(sb, S_IFDIR | 0755);
 884         if (!inode)
 885                 return -ENOMEM;
 886         root = d_alloc_root(inode);
 887         if (!root) {
 888                 iput(inode);
 889                 return -ENOMEM;
 890         }
 891         if (rpc_populate(root, files, RPCAUTH_Root + 1, RPCAUTH_RootEOF))
 892                 goto out;
 893         sb->s_root = root;
 894         return 0;
 895 out:
 896         d_genocide(root);
 897         dput(root);
 898         return -ENOMEM;
 899 }
 900
 901 static int
 902 rpc_get_sb(struct file_system_type *fs_type,
 903                 int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 904 {
 905         return get_sb_single(fs_type, flags, data, rpc_fill_super, mnt);
 906 }
 907
 908 static struct file_system_type rpc_pipe_fs_type = {
 909         .owner          = THIS_MODULE,
 910         .name           = "rpc_pipefs",
 911         .get_sb         = rpc_get_sb,
 912         .kill_sb        = kill_litter_super,
 913 };
 914
 915 static void
 916 init_once(void *foo)
 917 {
 918         struct rpc_inode *rpci = (struct rpc_inode *) foo;
 919
 920         inode_init_once(&rpci->vfs_inode);
 921         rpci->private = NULL;
 922         rpci->nreaders = 0;
 923         rpci->nwriters = 0;
 924         INIT_LIST_HEAD(&rpci->in_upcall);
 925         INIT_LIST_HEAD(&rpci->in_downcall);
 926         INIT_LIST_HEAD(&rpci->pipe);
 927         rpci->pipelen = 0;
 928         init_waitqueue_head(&rpci->waitq);
 929         INIT_DELAYED_WORK(&rpci->queue_timeout,
 930                             rpc_timeout_upcall_queue);
 931         rpci->ops = NULL;
 932 }
 933
 934 int register_rpc_pipefs(void)
 935 {
 936         int err;
 937
 938         rpc_inode_cachep = kmem_cache_create("rpc_inode_cache",
 939                                 sizeof(struct rpc_inode),
 940                                 0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
 941                                                 SLAB_MEM_SPREAD),
 942                                 init_once);
 943         if (!rpc_inode_cachep)
 944                 return -ENOMEM;
 945         err = register_filesystem(&rpc_pipe_fs_type);
 946         if (err) {
 947                 kmem_cache_destroy(rpc_inode_cachep);
 948                 return err;
 949         }
 950
 951         return 0;
 952 }
 953
 954 void unregister_rpc_pipefs(void)
 955 {
 956         kmem_cache_destroy(rpc_inode_cachep);
 957         unregister_filesystem(&rpc_pipe_fs_type);
 958 }