fs/autofs4/root.c

   1 /* -*- c -*- --------------------------------------------------------------- *
   2  *
   3  * linux/fs/autofs/root.c
   4  *
   5  *  Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
   6  *  Copyright 1999-2000 Jeremy Fitzhardinge <jeremy@goop.org>
   7  *
   8  * This file is part of the Linux kernel and is made available under
   9  * the terms of the GNU General Public License, version 2, or at your
  10  * option, any later version, incorporated herein by reference.
  11  *
  12  * ------------------------------------------------------------------------- */
  13
  14 #include <linux/errno.h>
  15 #include <linux/stat.h>
  16 #include <linux/param.h>
  17 #include <linux/time.h>
  18 #include <linux/smp_lock.h>
  19 #include "autofs_i.h"
  20
  21 static struct dentry *autofs4_dir_lookup(struct inode *,struct dentry *, struct nameidata *);
  22 static int autofs4_dir_symlink(struct inode *,struct dentry *,const char *);
  23 static int autofs4_dir_unlink(struct inode *,struct dentry *);
  24 static int autofs4_dir_rmdir(struct inode *,struct dentry *);
  25 static int autofs4_dir_mkdir(struct inode *,struct dentry *,int);
  26 static int autofs4_root_ioctl(struct inode *, struct file *,unsigned int,unsigned long);
  27 static struct dentry *autofs4_root_lookup(struct inode *,struct dentry *, struct nameidata *);
  28
  29 struct file_operations autofs4_root_operations = {
  30         .open           = dcache_dir_open,
  31         .release        = dcache_dir_close,
  32         .llseek         = dcache_dir_lseek,
  33         .read           = generic_read_dir,
  34         .readdir        = dcache_readdir,
  35         .ioctl          = autofs4_root_ioctl,
  36 };
  37
  38 struct inode_operations autofs4_root_inode_operations = {
  39         .lookup         = autofs4_root_lookup,
  40         .unlink         = autofs4_dir_unlink,
  41         .symlink        = autofs4_dir_symlink,
  42         .mkdir          = autofs4_dir_mkdir,
  43         .rmdir          = autofs4_dir_rmdir,
  44 };
  45
  46 struct inode_operations autofs4_dir_inode_operations = {
  47         .lookup         = autofs4_dir_lookup,
  48         .unlink         = autofs4_dir_unlink,
  49         .symlink        = autofs4_dir_symlink,
  50         .mkdir          = autofs4_dir_mkdir,
  51         .rmdir          = autofs4_dir_rmdir,
  52 };
  53
  54 /* Update usage from here to top of tree, so that scan of
  55    top-level directories will give a useful result */
  56 static void autofs4_update_usage(struct dentry *dentry)
  57 {
  58         struct dentry *top = dentry->d_sb->s_root;
  59
  60         for(; dentry != top; dentry = dentry->d_parent) {
  61                 struct autofs_info *ino = autofs4_dentry_ino(dentry);
  62
  63                 if (ino) {
  64                         update_atime(dentry->d_inode);
  65                         ino->last_used = jiffies;
  66                 }
  67         }
  68 }
  69
  70 static int try_to_fill_dentry(struct dentry *dentry,
  71                               struct super_block *sb,
  72                               struct autofs_sb_info *sbi)
  73 {
  74         struct autofs_info *de_info = autofs4_dentry_ino(dentry);
  75         int status = 0;
  76
  77         /* Block on any pending expiry here; invalidate the dentry
  78            when expiration is done to trigger mount request with a new
  79            dentry */
  80         if (de_info && (de_info->flags & AUTOFS_INF_EXPIRING)) {
  81                 DPRINTK(("try_to_fill_entry: waiting for expire %p name=%.*s, flags&PENDING=%s de_info=%p de_info->flags=%x\n",
  82                          dentry, dentry->d_name.len, dentry->d_name.name,
  83                          dentry->d_flags & DCACHE_AUTOFS_PENDING?"t":"f",
  84                          de_info, de_info?de_info->flags:0));
  85                 status = autofs4_wait(sbi, &dentry->d_name, NFY_NONE);
  86
  87                 DPRINTK(("try_to_fill_entry: expire done status=%d\n", status));
  88
  89                 return 0;
  90         }
  91
  92         DPRINTK(("try_to_fill_entry: dentry=%p %.*s ino=%p\n",
  93                  dentry, dentry->d_name.len, dentry->d_name.name, dentry->d_inode));
  94
  95         /* Wait for a pending mount, triggering one if there isn't one already */
  96         while(dentry->d_inode == NULL) {
  97                 DPRINTK(("try_to_fill_entry: waiting for mount name=%.*s, de_info=%p de_info->flags=%x\n",
  98                          dentry->d_name.len, dentry->d_name.name,
  99                          de_info, de_info?de_info->flags:0));
 100                 status = autofs4_wait(sbi, &dentry->d_name, NFY_MOUNT);
 101
 102                 DPRINTK(("try_to_fill_entry: mount done status=%d\n", status));
 103
 104                 if (status && dentry->d_inode)
 105                         return 0; /* Try to get the kernel to invalidate this dentry */
 106
 107                 /* Turn this into a real negative dentry? */
 108                 if (status == -ENOENT) {
 109                         dentry->d_time = jiffies + AUTOFS_NEGATIVE_TIMEOUT;
 110                         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 111                         return 1;
 112                 } else if (status) {
 113                         /* Return a negative dentry, but leave it "pending" */
 114                         return 1;
 115                 }
 116         }
 117
 118         /* If this is an unused directory that isn't a mount point,
 119            bitch at the daemon and fix it in user space */
 120         spin_lock(&dcache_lock);
 121         if (S_ISDIR(dentry->d_inode->i_mode) &&
 122             !d_mountpoint(dentry) &&
 123             list_empty(&dentry->d_subdirs)) {
 124                 DPRINTK(("try_to_fill_entry: mounting existing dir\n"));
 125                 spin_unlock(&dcache_lock);
 126                 return autofs4_wait(sbi, &dentry->d_name, NFY_MOUNT) == 0;
 127         }
 128         spin_unlock(&dcache_lock);
 129
 130         /* We don't update the usages for the autofs daemon itself, this
 131            is necessary for recursive autofs mounts */
 132         if (!autofs4_oz_mode(sbi))
 133                 autofs4_update_usage(dentry);
 134
 135         dentry->d_flags &= ~DCACHE_AUTOFS_PENDING;
 136         return 1;
 137 }
 138
 139
 140 /*
 141  * Revalidate is called on every cache lookup.  Some of those
 142  * cache lookups may actually happen while the dentry is not
 143  * yet completely filled in, and revalidate has to delay such
 144  * lookups..
 145  */
 146 static int autofs4_root_revalidate(struct dentry * dentry, struct nameidata *nd)
 147 {
 148         struct inode * dir = dentry->d_parent->d_inode;
 149         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 150         int oz_mode = autofs4_oz_mode(sbi);
 151
 152         /* Pending dentry */
 153         if (autofs4_ispending(dentry)) {
 154                 if (autofs4_oz_mode(sbi))
 155                         return 1;
 156                 else
 157                         return try_to_fill_dentry(dentry, dir->i_sb, sbi);
 158         }
 159
 160         /* Negative dentry.. invalidate if "old" */
 161         if (dentry->d_inode == NULL)
 162                 return (dentry->d_time - jiffies <= AUTOFS_NEGATIVE_TIMEOUT);
 163
 164         /* Check for a non-mountpoint directory with no contents */
 165         spin_lock(&dcache_lock);
 166         if (S_ISDIR(dentry->d_inode->i_mode) &&
 167             !d_mountpoint(dentry) &&
 168             list_empty(&dentry->d_subdirs)) {
 169                 DPRINTK(("autofs_root_revalidate: dentry=%p %.*s, emptydir\n",
 170                          dentry, dentry->d_name.len, dentry->d_name.name));
 171                 spin_unlock(&dcache_lock);
 172                 if (oz_mode)
 173                         return 1;
 174                 else
 175                         return try_to_fill_dentry(dentry, dir->i_sb, sbi);
 176         }
 177         spin_unlock(&dcache_lock);
 178
 179         /* Update the usage list */
 180         if (!oz_mode)
 181                 autofs4_update_usage(dentry);
 182
 183         return 1;
 184 }
 185
 186 static int autofs4_revalidate(struct dentry *dentry, struct nameidata *nd)
 187 {
 188         struct autofs_sb_info *sbi = autofs4_sbi(dentry->d_sb);
 189
 190         if (!autofs4_oz_mode(sbi))
 191                 autofs4_update_usage(dentry);
 192
 193         return 1;
 194 }
 195
 196 static void autofs4_dentry_release(struct dentry *de)
 197 {
 198         struct autofs_info *inf;
 199
 200         DPRINTK(("autofs4_dentry_release: releasing %p\n", de));
 201
 202         inf = autofs4_dentry_ino(de);
 203         de->d_fsdata = NULL;
 204
 205         if (inf) {
 206                 inf->dentry = NULL;
 207                 inf->inode = NULL;
 208
 209                 autofs4_free_ino(inf);
 210         }
 211 }
 212
 213 /* For dentries of directories in the root dir */
 214 static struct dentry_operations autofs4_root_dentry_operations = {
 215         .d_revalidate   = autofs4_root_revalidate,
 216         .d_release      = autofs4_dentry_release,
 217 };
 218
 219 /* For other dentries */
 220 static struct dentry_operations autofs4_dentry_operations = {
 221         .d_revalidate   = autofs4_revalidate,
 222         .d_release      = autofs4_dentry_release,
 223 };
 224
 225 /* Lookups in non-root dirs never find anything - if it's there, it's
 226    already in the dcache */
 227 /* SMP-safe */
 228 static struct dentry *autofs4_dir_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 229 {
 230 #if 0
 231         DPRINTK(("autofs_dir_lookup: ignoring lookup of %.*s/%.*s\n",
 232                  dentry->d_parent->d_name.len, dentry->d_parent->d_name.name,
 233                  dentry->d_name.len, dentry->d_name.name));
 234 #endif
 235
 236         dentry->d_fsdata = NULL;
 237         d_add(dentry, NULL);
 238         return NULL;
 239 }
 240
 241 /* Lookups in the root directory */
 242 static struct dentry *autofs4_root_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 243 {
 244         struct autofs_sb_info *sbi;
 245         int oz_mode;
 246
 247         DPRINTK(("autofs_root_lookup: name = %.*s\n",
 248                  dentry->d_name.len, dentry->d_name.name));
 249
 250         if (dentry->d_name.len > NAME_MAX)
 251                 return ERR_PTR(-ENAMETOOLONG);/* File name too long to exist */
 252
 253         sbi = autofs4_sbi(dir->i_sb);
 254
 255         lock_kernel();
 256         oz_mode = autofs4_oz_mode(sbi);
 257         DPRINTK(("autofs_lookup: pid = %u, pgrp = %u, catatonic = %d, oz_mode = %d\n",
 258                  current->pid, current->pgrp, sbi->catatonic, oz_mode));
 259
 260         /*
 261          * Mark the dentry incomplete, but add it. This is needed so
 262          * that the VFS layer knows about the dentry, and we can count
 263          * on catching any lookups through the revalidate.
 264          *
 265          * Let all the hard work be done by the revalidate function that
 266          * needs to be able to do this anyway..
 267          *
 268          * We need to do this before we release the directory semaphore.
 269          */
 270         dentry->d_op = &autofs4_root_dentry_operations;
 271
 272         if (!oz_mode)
 273                 dentry->d_flags |= DCACHE_AUTOFS_PENDING;
 274         dentry->d_fsdata = NULL;
 275         d_add(dentry, NULL);
 276
 277         if (dentry->d_op && dentry->d_op->d_revalidate) {
 278                 up(&dir->i_sem);
 279                 (dentry->d_op->d_revalidate)(dentry, nd);
 280                 down(&dir->i_sem);
 281         }
 282
 283         /*
 284          * If we are still pending, check if we had to handle
 285          * a signal. If so we can force a restart..
 286          */
 287         if (dentry->d_flags & DCACHE_AUTOFS_PENDING) {
 288                 if (signal_pending(current)) {
 289                         unlock_kernel();
 290                         return ERR_PTR(-ERESTARTNOINTR);
 291                 }
 292         }
 293         unlock_kernel();
 294
 295         /*
 296          * If this dentry is unhashed, then we shouldn't honour this
 297          * lookup even if the dentry is positive.  Returning ENOENT here
 298          * doesn't do the right thing for all system calls, but it should
 299          * be OK for the operations we permit from an autofs.
 300          */
 301         if ( dentry->d_inode && d_unhashed(dentry) )
 302                 return ERR_PTR(-ENOENT);
 303
 304         return NULL;
 305 }
 306
 307 static int autofs4_dir_symlink(struct inode *dir,
 308                                struct dentry *dentry,
 309                                const char *symname)
 310 {
 311         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 312         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 313         struct inode *inode;
 314         char *cp;
 315
 316         DPRINTK(("autofs_dir_symlink: %s <- %.*s\n", symname,
 317                  dentry->d_name.len, dentry->d_name.name));
 318
 319         lock_kernel();
 320         if (!autofs4_oz_mode(sbi)) {
 321                 unlock_kernel();
 322                 return -EACCES;
 323         }
 324
 325         ino = autofs4_init_ino(ino, sbi, S_IFLNK | 0555);
 326         if (ino == NULL) {
 327                 unlock_kernel();
 328                 return -ENOSPC;
 329         }
 330
 331         ino->size = strlen(symname);
 332         ino->u.symlink = cp = kmalloc(ino->size + 1, GFP_KERNEL);
 333
 334         if (cp == NULL) {
 335                 kfree(ino);
 336                 unlock_kernel();
 337                 return -ENOSPC;
 338         }
 339
 340         strcpy(cp, symname);
 341
 342         inode = autofs4_get_inode(dir->i_sb, ino);
 343         d_instantiate(dentry, inode);
 344
 345         if (dir == dir->i_sb->s_root->d_inode)
 346                 dentry->d_op = &autofs4_root_dentry_operations;
 347         else
 348                 dentry->d_op = &autofs4_dentry_operations;
 349
 350         dentry->d_fsdata = ino;
 351         ino->dentry = dget(dentry);
 352         ino->inode = inode;
 353
 354         dir->i_mtime = CURRENT_TIME;
 355
 356         unlock_kernel();
 357         return 0;
 358 }
 359
 360 /*
 361  * NOTE!
 362  *
 363  * Normal filesystems would do a "d_delete()" to tell the VFS dcache
 364  * that the file no longer exists. However, doing that means that the
 365  * VFS layer can turn the dentry into a negative dentry.  We don't want
 366  * this, because since the unlink is probably the result of an expire.
 367  * We simply d_drop it, which allows the dentry lookup to remount it
 368  * if necessary.
 369  *
 370  * If a process is blocked on the dentry waiting for the expire to finish,
 371  * it will invalidate the dentry and try to mount with a new one.
 372  *
 373  * Also see autofs_dir_rmdir()..
 374  */
 375 static int autofs4_dir_unlink(struct inode *dir, struct dentry *dentry)
 376 {
 377         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 378         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 379
 380         /* This allows root to remove symlinks */
 381         lock_kernel();
 382         if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) ) {
 383                 unlock_kernel();
 384                 return -EACCES;
 385         }
 386
 387         dput(ino->dentry);
 388
 389         dentry->d_inode->i_size = 0;
 390         dentry->d_inode->i_nlink = 0;
 391
 392         dir->i_mtime = CURRENT_TIME;
 393
 394         d_drop(dentry);
 395
 396         unlock_kernel();
 397
 398         return 0;
 399 }
 400
 401 static int autofs4_dir_rmdir(struct inode *dir, struct dentry *dentry)
 402 {
 403         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 404         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 405
 406         lock_kernel();
 407         if (!autofs4_oz_mode(sbi)) {
 408                 unlock_kernel();
 409                 return -EACCES;
 410         }
 411
 412         spin_lock(&dcache_lock);
 413         if (!list_empty(&dentry->d_subdirs)) {
 414                 spin_unlock(&dcache_lock);
 415                 unlock_kernel();
 416                 return -ENOTEMPTY;
 417         }
 418         __d_drop(dentry);
 419         spin_unlock(&dcache_lock);
 420
 421         dput(ino->dentry);
 422
 423         dentry->d_inode->i_size = 0;
 424         dentry->d_inode->i_nlink = 0;
 425
 426         if (dir->i_nlink)
 427                 dir->i_nlink--;
 428
 429         unlock_kernel();
 430         return 0;
 431 }
 432
 433
 434
 435 static int autofs4_dir_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 436 {
 437         struct autofs_sb_info *sbi = autofs4_sbi(dir->i_sb);
 438         struct autofs_info *ino = autofs4_dentry_ino(dentry);
 439         struct inode *inode;
 440
 441         lock_kernel();
 442         if ( !autofs4_oz_mode(sbi) ) {
 443                 unlock_kernel();
 444                 return -EACCES;
 445         }
 446
 447         DPRINTK(("autofs_dir_mkdir: dentry %p, creating %.*s\n",
 448                  dentry, dentry->d_name.len, dentry->d_name.name));
 449
 450         ino = autofs4_init_ino(ino, sbi, S_IFDIR | 0555);
 451         if (ino == NULL) {
 452                 unlock_kernel();
 453                 return -ENOSPC;
 454         }
 455
 456         inode = autofs4_get_inode(dir->i_sb, ino);
 457         d_instantiate(dentry, inode);
 458
 459         if (dir == dir->i_sb->s_root->d_inode)
 460                 dentry->d_op = &autofs4_root_dentry_operations;
 461         else
 462                 dentry->d_op = &autofs4_dentry_operations;
 463
 464         dentry->d_fsdata = ino;
 465         ino->dentry = dget(dentry);
 466         ino->inode = inode;
 467         dir->i_nlink++;
 468         dir->i_mtime = CURRENT_TIME;
 469
 470         unlock_kernel();
 471         return 0;
 472 }
 473
 474 /* Get/set timeout ioctl() operation */
 475 static inline int autofs4_get_set_timeout(struct autofs_sb_info *sbi,
 476                                          unsigned long *p)
 477 {
 478         int rv;
 479         unsigned long ntimeout;
 480
 481         if ( (rv = get_user(ntimeout, p)) ||
 482              (rv = put_user(sbi->exp_timeout/HZ, p)) )
 483                 return rv;
 484
 485         if ( ntimeout > ULONG_MAX/HZ )
 486                 sbi->exp_timeout = 0;
 487         else
 488                 sbi->exp_timeout = ntimeout * HZ;
 489
 490         return 0;
 491 }
 492
 493 /* Return protocol version */
 494 static inline int autofs4_get_protover(struct autofs_sb_info *sbi, int *p)
 495 {
 496         return put_user(sbi->version, p);
 497 }
 498
 499 /* Identify autofs_dentries - this is so we can tell if there's
 500    an extra dentry refcount or not.  We only hold a refcount on the
 501    dentry if its non-negative (ie, d_inode != NULL)
 502 */
 503 int is_autofs4_dentry(struct dentry *dentry)
 504 {
 505         return dentry && dentry->d_inode &&
 506                 (dentry->d_op == &autofs4_root_dentry_operations ||
 507                  dentry->d_op == &autofs4_dentry_operations) &&
 508                 dentry->d_fsdata != NULL;
 509 }
 510
 511 /*
 512  * ioctl()'s on the root directory is the chief method for the daemon to
 513  * generate kernel reactions
 514  */
 515 static int autofs4_root_ioctl(struct inode *inode, struct file *filp,
 516                              unsigned int cmd, unsigned long arg)
 517 {
 518         struct autofs_sb_info *sbi = autofs4_sbi(inode->i_sb);
 519
 520         DPRINTK(("autofs_ioctl: cmd = 0x%08x, arg = 0x%08lx, sbi = %p, pgrp = %u\n",
 521                  cmd,arg,sbi,current->pgrp));
 522
 523         if ( _IOC_TYPE(cmd) != _IOC_TYPE(AUTOFS_IOC_FIRST) ||
 524              _IOC_NR(cmd) - _IOC_NR(AUTOFS_IOC_FIRST) >= AUTOFS_IOC_COUNT )
 525                 return -ENOTTY;
 526
 527         if ( !autofs4_oz_mode(sbi) && !capable(CAP_SYS_ADMIN) )
 528                 return -EPERM;
 529
 530         switch(cmd) {
 531         case AUTOFS_IOC_READY:  /* Wait queue: go ahead and retry */
 532                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,0);
 533         case AUTOFS_IOC_FAIL:   /* Wait queue: fail with ENOENT */
 534                 return autofs4_wait_release(sbi,(autofs_wqt_t)arg,-ENOENT);
 535         case AUTOFS_IOC_CATATONIC: /* Enter catatonic mode (daemon shutdown) */
 536                 autofs4_catatonic_mode(sbi);
 537                 return 0;
 538         case AUTOFS_IOC_PROTOVER: /* Get protocol version */
 539                 return autofs4_get_protover(sbi, (int *)arg);
 540         case AUTOFS_IOC_SETTIMEOUT:
 541                 return autofs4_get_set_timeout(sbi,(unsigned long *)arg);
 542
 543         /* return a single thing to expire */
 544         case AUTOFS_IOC_EXPIRE:
 545                 return autofs4_expire_run(inode->i_sb,filp->f_vfsmnt,sbi,
 546                                           (struct autofs_packet_expire *)arg);
 547         /* same as above, but can send multiple expires through pipe */
 548         case AUTOFS_IOC_EXPIRE_MULTI:
 549                 return autofs4_expire_multi(inode->i_sb,filp->f_vfsmnt,sbi,
 550                                             (int *)arg);
 551
 552         default:
 553                 return -ENOSYS;
 554         }
 555 }