fs/afs/proc.c

   1 /* /proc interface for AFS
   2  *
   3  * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/slab.h>
  13 #include <linux/module.h>
  14 #include <linux/proc_fs.h>
  15 #include <linux/seq_file.h>
  16 #include <linux/sched.h>
  17 #include <asm/uaccess.h>
  18 #include "internal.h"
  19
  20 static struct proc_dir_entry *proc_afs;
  21
  22
  23 static int afs_proc_cells_open(struct inode *inode, struct file *file);
  24 static void *afs_proc_cells_start(struct seq_file *p, loff_t *pos);
  25 static void *afs_proc_cells_next(struct seq_file *p, void *v, loff_t *pos);
  26 static void afs_proc_cells_stop(struct seq_file *p, void *v);
  27 static int afs_proc_cells_show(struct seq_file *m, void *v);
  28 static ssize_t afs_proc_cells_write(struct file *file, const char __user *buf,
  29                                     size_t size, loff_t *_pos);
  30
  31 static struct seq_operations afs_proc_cells_ops = {
  32         .start  = afs_proc_cells_start,
  33         .next   = afs_proc_cells_next,
  34         .stop   = afs_proc_cells_stop,
  35         .show   = afs_proc_cells_show,
  36 };
  37
  38 static const struct file_operations afs_proc_cells_fops = {
  39         .open           = afs_proc_cells_open,
  40         .read           = seq_read,
  41         .write          = afs_proc_cells_write,
  42         .llseek         = seq_lseek,
  43         .release        = seq_release,
  44         .owner          = THIS_MODULE,
  45 };
  46
  47 static int afs_proc_rootcell_open(struct inode *inode, struct file *file);
  48 static int afs_proc_rootcell_release(struct inode *inode, struct file *file);
  49 static ssize_t afs_proc_rootcell_read(struct file *file, char __user *buf,
  50                                       size_t size, loff_t *_pos);
  51 static ssize_t afs_proc_rootcell_write(struct file *file,
  52                                        const char __user *buf,
  53                                        size_t size, loff_t *_pos);
  54
  55 static const struct file_operations afs_proc_rootcell_fops = {
  56         .open           = afs_proc_rootcell_open,
  57         .read           = afs_proc_rootcell_read,
  58         .write          = afs_proc_rootcell_write,
  59         .llseek         = no_llseek,
  60         .release        = afs_proc_rootcell_release,
  61         .owner          = THIS_MODULE,
  62 };
  63
  64 static int afs_proc_cell_volumes_open(struct inode *inode, struct file *file);
  65 static int afs_proc_cell_volumes_release(struct inode *inode,
  66                                          struct file *file);
  67 static void *afs_proc_cell_volumes_start(struct seq_file *p, loff_t *pos);
  68 static void *afs_proc_cell_volumes_next(struct seq_file *p, void *v,
  69                                         loff_t *pos);
  70 static void afs_proc_cell_volumes_stop(struct seq_file *p, void *v);
  71 static int afs_proc_cell_volumes_show(struct seq_file *m, void *v);
  72
  73 static struct seq_operations afs_proc_cell_volumes_ops = {
  74         .start  = afs_proc_cell_volumes_start,
  75         .next   = afs_proc_cell_volumes_next,
  76         .stop   = afs_proc_cell_volumes_stop,
  77         .show   = afs_proc_cell_volumes_show,
  78 };
  79
  80 static const struct file_operations afs_proc_cell_volumes_fops = {
  81         .open           = afs_proc_cell_volumes_open,
  82         .read           = seq_read,
  83         .llseek         = seq_lseek,
  84         .release        = afs_proc_cell_volumes_release,
  85         .owner          = THIS_MODULE,
  86 };
  87
  88 static int afs_proc_cell_vlservers_open(struct inode *inode,
  89                                         struct file *file);
  90 static int afs_proc_cell_vlservers_release(struct inode *inode,
  91                                            struct file *file);
  92 static void *afs_proc_cell_vlservers_start(struct seq_file *p, loff_t *pos);
  93 static void *afs_proc_cell_vlservers_next(struct seq_file *p, void *v,
  94                                           loff_t *pos);
  95 static void afs_proc_cell_vlservers_stop(struct seq_file *p, void *v);
  96 static int afs_proc_cell_vlservers_show(struct seq_file *m, void *v);
  97
  98 static struct seq_operations afs_proc_cell_vlservers_ops = {
  99         .start  = afs_proc_cell_vlservers_start,
 100         .next   = afs_proc_cell_vlservers_next,
 101         .stop   = afs_proc_cell_vlservers_stop,
 102         .show   = afs_proc_cell_vlservers_show,
 103 };
 104
 105 static const struct file_operations afs_proc_cell_vlservers_fops = {
 106         .open           = afs_proc_cell_vlservers_open,
 107         .read           = seq_read,
 108         .llseek         = seq_lseek,
 109         .release        = afs_proc_cell_vlservers_release,
 110         .owner          = THIS_MODULE,
 111 };
 112
 113 static int afs_proc_cell_servers_open(struct inode *inode, struct file *file);
 114 static int afs_proc_cell_servers_release(struct inode *inode,
 115                                          struct file *file);
 116 static void *afs_proc_cell_servers_start(struct seq_file *p, loff_t *pos);
 117 static void *afs_proc_cell_servers_next(struct seq_file *p, void *v,
 118                                         loff_t *pos);
 119 static void afs_proc_cell_servers_stop(struct seq_file *p, void *v);
 120 static int afs_proc_cell_servers_show(struct seq_file *m, void *v);
 121
 122 static struct seq_operations afs_proc_cell_servers_ops = {
 123         .start  = afs_proc_cell_servers_start,
 124         .next   = afs_proc_cell_servers_next,
 125         .stop   = afs_proc_cell_servers_stop,
 126         .show   = afs_proc_cell_servers_show,
 127 };
 128
 129 static const struct file_operations afs_proc_cell_servers_fops = {
 130         .open           = afs_proc_cell_servers_open,
 131         .read           = seq_read,
 132         .llseek         = seq_lseek,
 133         .release        = afs_proc_cell_servers_release,
 134         .owner          = THIS_MODULE,
 135 };
 136
 137 /*
 138  * initialise the /proc/fs/afs/ directory
 139  */
 140 int afs_proc_init(void)
 141 {
 142         struct proc_dir_entry *p;
 143
 144         _enter("");
 145
 146         proc_afs = proc_mkdir("fs/afs", NULL);
 147         if (!proc_afs)
 148                 goto error_dir;
 149         proc_afs->owner = THIS_MODULE;
 150
 151         p = proc_create("cells", 0, proc_afs, &afs_proc_cells_fops);
 152         if (!p)
 153                 goto error_cells;
 154
 155         p = proc_create("rootcell", 0, proc_afs, &afs_proc_rootcell_fops);
 156         if (!p)
 157                 goto error_rootcell;
 158
 159         _leave(" = 0");
 160         return 0;
 161
 162 error_rootcell:
 163         remove_proc_entry("cells", proc_afs);
 164 error_cells:
 165         remove_proc_entry("fs/afs", NULL);
 166 error_dir:
 167         _leave(" = -ENOMEM");
 168         return -ENOMEM;
 169 }
 170
 171 /*
 172  * clean up the /proc/fs/afs/ directory
 173  */
 174 void afs_proc_cleanup(void)
 175 {
 176         remove_proc_entry("rootcell", proc_afs);
 177         remove_proc_entry("cells", proc_afs);
 178         remove_proc_entry("fs/afs", NULL);
 179 }
 180
 181 /*
 182  * open "/proc/fs/afs/cells" which provides a summary of extant cells
 183  */
 184 static int afs_proc_cells_open(struct inode *inode, struct file *file)
 185 {
 186         struct seq_file *m;
 187         int ret;
 188
 189         ret = seq_open(file, &afs_proc_cells_ops);
 190         if (ret < 0)
 191                 return ret;
 192
 193         m = file->private_data;
 194         m->private = PDE(inode)->data;
 195
 196         return 0;
 197 }
 198
 199 /*
 200  * set up the iterator to start reading from the cells list and return the
 201  * first item
 202  */
 203 static void *afs_proc_cells_start(struct seq_file *m, loff_t *_pos)
 204 {
 205         /* lock the list against modification */
 206         down_read(&afs_proc_cells_sem);
 207         return seq_list_start_head(&afs_proc_cells, *_pos);
 208 }
 209
 210 /*
 211  * move to next cell in cells list
 212  */
 213 static void *afs_proc_cells_next(struct seq_file *p, void *v, loff_t *pos)
 214 {
 215         return seq_list_next(v, &afs_proc_cells, pos);
 216 }
 217
 218 /*
 219  * clean up after reading from the cells list
 220  */
 221 static void afs_proc_cells_stop(struct seq_file *p, void *v)
 222 {
 223         up_read(&afs_proc_cells_sem);
 224 }
 225
 226 /*
 227  * display a header line followed by a load of cell lines
 228  */
 229 static int afs_proc_cells_show(struct seq_file *m, void *v)
 230 {
 231         struct afs_cell *cell = list_entry(v, struct afs_cell, proc_link);
 232
 233         if (v == &afs_proc_cells) {
 234                 /* display header on line 1 */
 235                 seq_puts(m, "USE NAME\n");
 236                 return 0;
 237         }
 238
 239         /* display one cell per line on subsequent lines */
 240         seq_printf(m, "%3d %s\n",
 241                    atomic_read(&cell->usage), cell->name);
 242         return 0;
 243 }
 244
 245 /*
 246  * handle writes to /proc/fs/afs/cells
 247  * - to add cells: echo "add <cellname> <IP>[:<IP>][:<IP>]"
 248  */
 249 static ssize_t afs_proc_cells_write(struct file *file, const char __user *buf,
 250                                     size_t size, loff_t *_pos)
 251 {
 252         char *kbuf, *name, *args;
 253         int ret;
 254
 255         /* start by dragging the command into memory */
 256         if (size <= 1 || size >= PAGE_SIZE)
 257                 return -EINVAL;
 258
 259         kbuf = kmalloc(size + 1, GFP_KERNEL);
 260         if (!kbuf)
 261                 return -ENOMEM;
 262
 263         ret = -EFAULT;
 264         if (copy_from_user(kbuf, buf, size) != 0)
 265                 goto done;
 266         kbuf[size] = 0;
 267
 268         /* trim to first NL */
 269         name = memchr(kbuf, '\n', size);
 270         if (name)
 271                 *name = 0;
 272
 273         /* split into command, name and argslist */
 274         name = strchr(kbuf, ' ');
 275         if (!name)
 276                 goto inval;
 277         do {
 278                 *name++ = 0;
 279         } while(*name == ' ');
 280         if (!*name)
 281                 goto inval;
 282
 283         args = strchr(name, ' ');
 284         if (!args)
 285                 goto inval;
 286         do {
 287                 *args++ = 0;
 288         } while(*args == ' ');
 289         if (!*args)
 290                 goto inval;
 291
 292         /* determine command to perform */
 293         _debug("cmd=%s name=%s args=%s", kbuf, name, args);
 294
 295         if (strcmp(kbuf, "add") == 0) {
 296                 struct afs_cell *cell;
 297
 298                 cell = afs_cell_create(name, args);
 299                 if (IS_ERR(cell)) {
 300                         ret = PTR_ERR(cell);
 301                         goto done;
 302                 }
 303
 304                 afs_put_cell(cell);
 305                 printk("kAFS: Added new cell '%s'\n", name);
 306         } else {
 307                 goto inval;
 308         }
 309
 310         ret = size;
 311
 312 done:
 313         kfree(kbuf);
 314         _leave(" = %d", ret);
 315         return ret;
 316
 317 inval:
 318         ret = -EINVAL;
 319         printk("kAFS: Invalid Command on /proc/fs/afs/cells file\n");
 320         goto done;
 321 }
 322
 323 /*
 324  * Stubs for /proc/fs/afs/rootcell
 325  */
 326 static int afs_proc_rootcell_open(struct inode *inode, struct file *file)
 327 {
 328         return 0;
 329 }
 330
 331 static int afs_proc_rootcell_release(struct inode *inode, struct file *file)
 332 {
 333         return 0;
 334 }
 335
 336 static ssize_t afs_proc_rootcell_read(struct file *file, char __user *buf,
 337                                       size_t size, loff_t *_pos)
 338 {
 339         return 0;
 340 }
 341
 342 /*
 343  * handle writes to /proc/fs/afs/rootcell
 344  * - to initialize rootcell: echo "cell.name:192.168.231.14"
 345  */
 346 static ssize_t afs_proc_rootcell_write(struct file *file,
 347                                        const char __user *buf,
 348                                        size_t size, loff_t *_pos)
 349 {
 350         char *kbuf, *s;
 351         int ret;
 352
 353         /* start by dragging the command into memory */
 354         if (size <= 1 || size >= PAGE_SIZE)
 355                 return -EINVAL;
 356
 357         ret = -ENOMEM;
 358         kbuf = kmalloc(size + 1, GFP_KERNEL);
 359         if (!kbuf)
 360                 goto nomem;
 361
 362         ret = -EFAULT;
 363         if (copy_from_user(kbuf, buf, size) != 0)
 364                 goto infault;
 365         kbuf[size] = 0;
 366
 367         /* trim to first NL */
 368         s = memchr(kbuf, '\n', size);
 369         if (s)
 370                 *s = 0;
 371
 372         /* determine command to perform */
 373         _debug("rootcell=%s", kbuf);
 374
 375         ret = afs_cell_init(kbuf);
 376         if (ret >= 0)
 377                 ret = size;     /* consume everything, always */
 378
 379 infault:
 380         kfree(kbuf);
 381 nomem:
 382         _leave(" = %d", ret);
 383         return ret;
 384 }
 385
 386 /*
 387  * initialise /proc/fs/afs/<cell>/
 388  */
 389 int afs_proc_cell_setup(struct afs_cell *cell)
 390 {
 391         struct proc_dir_entry *p;
 392
 393         _enter("%p{%s}", cell, cell->name);
 394
 395         cell->proc_dir = proc_mkdir(cell->name, proc_afs);
 396         if (!cell->proc_dir)
 397                 goto error_dir;
 398
 399         p = proc_create_data("servers", 0, cell->proc_dir,
 400                              &afs_proc_cell_servers_fops, cell);
 401         if (!p)
 402                 goto error_servers;
 403
 404         p = proc_create_data("vlservers", 0, cell->proc_dir,
 405                              &afs_proc_cell_vlservers_fops, cell);
 406         if (!p)
 407                 goto error_vlservers;
 408
 409         p = proc_create_data("volumes", 0, cell->proc_dir,
 410                              &afs_proc_cell_volumes_fops, cell);
 411         if (!p)
 412                 goto error_volumes;
 413
 414         _leave(" = 0");
 415         return 0;
 416
 417 error_volumes:
 418         remove_proc_entry("vlservers", cell->proc_dir);
 419 error_vlservers:
 420         remove_proc_entry("servers", cell->proc_dir);
 421 error_servers:
 422         remove_proc_entry(cell->name, proc_afs);
 423 error_dir:
 424         _leave(" = -ENOMEM");
 425         return -ENOMEM;
 426 }
 427
 428 /*
 429  * remove /proc/fs/afs/<cell>/
 430  */
 431 void afs_proc_cell_remove(struct afs_cell *cell)
 432 {
 433         _enter("");
 434
 435         remove_proc_entry("volumes", cell->proc_dir);
 436         remove_proc_entry("vlservers", cell->proc_dir);
 437         remove_proc_entry("servers", cell->proc_dir);
 438         remove_proc_entry(cell->name, proc_afs);
 439
 440         _leave("");
 441 }
 442
 443 /*
 444  * open "/proc/fs/afs/<cell>/volumes" which provides a summary of extant cells
 445  */
 446 static int afs_proc_cell_volumes_open(struct inode *inode, struct file *file)
 447 {
 448         struct afs_cell *cell;
 449         struct seq_file *m;
 450         int ret;
 451
 452         cell = PDE(inode)->data;
 453         if (!cell)
 454                 return -ENOENT;
 455
 456         ret = seq_open(file, &afs_proc_cell_volumes_ops);
 457         if (ret < 0)
 458                 return ret;
 459
 460         m = file->private_data;
 461         m->private = cell;
 462
 463         return 0;
 464 }
 465
 466 /*
 467  * close the file and release the ref to the cell
 468  */
 469 static int afs_proc_cell_volumes_release(struct inode *inode, struct file *file)
 470 {
 471         return seq_release(inode, file);
 472 }
 473
 474 /*
 475  * set up the iterator to start reading from the cells list and return the
 476  * first item
 477  */
 478 static void *afs_proc_cell_volumes_start(struct seq_file *m, loff_t *_pos)
 479 {
 480         struct afs_cell *cell = m->private;
 481
 482         _enter("cell=%p pos=%Ld", cell, *_pos);
 483
 484         /* lock the list against modification */
 485         down_read(&cell->vl_sem);
 486         return seq_list_start_head(&cell->vl_list, *_pos);
 487 }
 488
 489 /*
 490  * move to next cell in cells list
 491  */
 492 static void *afs_proc_cell_volumes_next(struct seq_file *p, void *v,
 493                                         loff_t *_pos)
 494 {
 495         struct afs_cell *cell = p->private;
 496
 497         _enter("cell=%p pos=%Ld", cell, *_pos);
 498         return seq_list_next(v, &cell->vl_list, _pos);
 499 }
 500
 501 /*
 502  * clean up after reading from the cells list
 503  */
 504 static void afs_proc_cell_volumes_stop(struct seq_file *p, void *v)
 505 {
 506         struct afs_cell *cell = p->private;
 507
 508         up_read(&cell->vl_sem);
 509 }
 510
 511 static const char afs_vlocation_states[][4] = {
 512         [AFS_VL_NEW]                    = "New",
 513         [AFS_VL_CREATING]               = "Crt",
 514         [AFS_VL_VALID]                  = "Val",
 515         [AFS_VL_NO_VOLUME]              = "NoV",
 516         [AFS_VL_UPDATING]               = "Upd",
 517         [AFS_VL_VOLUME_DELETED]         = "Del",
 518         [AFS_VL_UNCERTAIN]              = "Unc",
 519 };
 520
 521 /*
 522  * display a header line followed by a load of volume lines
 523  */
 524 static int afs_proc_cell_volumes_show(struct seq_file *m, void *v)
 525 {
 526         struct afs_cell *cell = m->private;
 527         struct afs_vlocation *vlocation =
 528                 list_entry(v, struct afs_vlocation, link);
 529
 530         /* display header on line 1 */
 531         if (v == &cell->vl_list) {
 532                 seq_puts(m, "USE STT VLID[0]  VLID[1]  VLID[2]  NAME\n");
 533                 return 0;
 534         }
 535
 536         /* display one cell per line on subsequent lines */
 537         seq_printf(m, "%3d %s %08x %08x %08x %s\n",
 538                    atomic_read(&vlocation->usage),
 539                    afs_vlocation_states[vlocation->state],
 540                    vlocation->vldb.vid[0],
 541                    vlocation->vldb.vid[1],
 542                    vlocation->vldb.vid[2],
 543                    vlocation->vldb.name);
 544
 545         return 0;
 546 }
 547
 548 /*
 549  * open "/proc/fs/afs/<cell>/vlservers" which provides a list of volume
 550  * location server
 551  */
 552 static int afs_proc_cell_vlservers_open(struct inode *inode, struct file *file)
 553 {
 554         struct afs_cell *cell;
 555         struct seq_file *m;
 556         int ret;
 557
 558         cell = PDE(inode)->data;
 559         if (!cell)
 560                 return -ENOENT;
 561
 562         ret = seq_open(file, &afs_proc_cell_vlservers_ops);
 563         if (ret<0)
 564                 return ret;
 565
 566         m = file->private_data;
 567         m->private = cell;
 568
 569         return 0;
 570 }
 571
 572 /*
 573  * close the file and release the ref to the cell
 574  */
 575 static int afs_proc_cell_vlservers_release(struct inode *inode,
 576                                            struct file *file)
 577 {
 578         return seq_release(inode, file);
 579 }
 580
 581 /*
 582  * set up the iterator to start reading from the cells list and return the
 583  * first item
 584  */
 585 static void *afs_proc_cell_vlservers_start(struct seq_file *m, loff_t *_pos)
 586 {
 587         struct afs_cell *cell = m->private;
 588         loff_t pos = *_pos;
 589
 590         _enter("cell=%p pos=%Ld", cell, *_pos);
 591
 592         /* lock the list against modification */
 593         down_read(&cell->vl_sem);
 594
 595         /* allow for the header line */
 596         if (!pos)
 597                 return (void *) 1;
 598         pos--;
 599
 600         if (pos >= cell->vl_naddrs)
 601                 return NULL;
 602
 603         return &cell->vl_addrs[pos];
 604 }
 605
 606 /*
 607  * move to next cell in cells list
 608  */
 609 static void *afs_proc_cell_vlservers_next(struct seq_file *p, void *v,
 610                                           loff_t *_pos)
 611 {
 612         struct afs_cell *cell = p->private;
 613         loff_t pos;
 614
 615         _enter("cell=%p{nad=%u} pos=%Ld", cell, cell->vl_naddrs, *_pos);
 616
 617         pos = *_pos;
 618         (*_pos)++;
 619         if (pos >= cell->vl_naddrs)
 620                 return NULL;
 621
 622         return &cell->vl_addrs[pos];
 623 }
 624
 625 /*
 626  * clean up after reading from the cells list
 627  */
 628 static void afs_proc_cell_vlservers_stop(struct seq_file *p, void *v)
 629 {
 630         struct afs_cell *cell = p->private;
 631
 632         up_read(&cell->vl_sem);
 633 }
 634
 635 /*
 636  * display a header line followed by a load of volume lines
 637  */
 638 static int afs_proc_cell_vlservers_show(struct seq_file *m, void *v)
 639 {
 640         struct in_addr *addr = v;
 641
 642         /* display header on line 1 */
 643         if (v == (struct in_addr *) 1) {
 644                 seq_puts(m, "ADDRESS\n");
 645                 return 0;
 646         }
 647
 648         /* display one cell per line on subsequent lines */
 649         seq_printf(m, "%pI4\n", &addr->s_addr);
 650         return 0;
 651 }
 652
 653 /*
 654  * open "/proc/fs/afs/<cell>/servers" which provides a summary of active
 655  * servers
 656  */
 657 static int afs_proc_cell_servers_open(struct inode *inode, struct file *file)
 658 {
 659         struct afs_cell *cell;
 660         struct seq_file *m;
 661         int ret;
 662
 663         cell = PDE(inode)->data;
 664         if (!cell)
 665                 return -ENOENT;
 666
 667         ret = seq_open(file, &afs_proc_cell_servers_ops);
 668         if (ret < 0)
 669                 return ret;
 670
 671         m = file->private_data;
 672         m->private = cell;
 673         return 0;
 674 }
 675
 676 /*
 677  * close the file and release the ref to the cell
 678  */
 679 static int afs_proc_cell_servers_release(struct inode *inode,
 680                                          struct file *file)
 681 {
 682         return seq_release(inode, file);
 683 }
 684
 685 /*
 686  * set up the iterator to start reading from the cells list and return the
 687  * first item
 688  */
 689 static void *afs_proc_cell_servers_start(struct seq_file *m, loff_t *_pos)
 690         __acquires(m->private->servers_lock)
 691 {
 692         struct afs_cell *cell = m->private;
 693
 694         _enter("cell=%p pos=%Ld", cell, *_pos);
 695
 696         /* lock the list against modification */
 697         read_lock(&cell->servers_lock);
 698         return seq_list_start_head(&cell->servers, *_pos);
 699 }
 700
 701 /*
 702  * move to next cell in cells list
 703  */
 704 static void *afs_proc_cell_servers_next(struct seq_file *p, void *v,
 705                                         loff_t *_pos)
 706 {
 707         struct afs_cell *cell = p->private;
 708
 709         _enter("cell=%p pos=%Ld", cell, *_pos);
 710         return seq_list_next(v, &cell->servers, _pos);
 711 }
 712
 713 /*
 714  * clean up after reading from the cells list
 715  */
 716 static void afs_proc_cell_servers_stop(struct seq_file *p, void *v)
 717         __releases(p->private->servers_lock)
 718 {
 719         struct afs_cell *cell = p->private;
 720
 721         read_unlock(&cell->servers_lock);
 722 }
 723
 724 /*
 725  * display a header line followed by a load of volume lines
 726  */
 727 static int afs_proc_cell_servers_show(struct seq_file *m, void *v)
 728 {
 729         struct afs_cell *cell = m->private;
 730         struct afs_server *server = list_entry(v, struct afs_server, link);
 731         char ipaddr[20];
 732
 733         /* display header on line 1 */
 734         if (v == &cell->servers) {
 735                 seq_puts(m, "USE ADDR            STATE\n");
 736                 return 0;
 737         }
 738
 739         /* display one cell per line on subsequent lines */
 740         sprintf(ipaddr, "%pI4", &server->addr);
 741         seq_printf(m, "%3d %-15.15s %5d\n",
 742                    atomic_read(&server->usage), ipaddr, server->fs_state);
 743
 744         return 0;
 745 }