module/zfs/zpl_ctldir.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright (C) 2011 Lawrence Livermore National Security, LLC.
  23  * Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
  24  * LLNL-CODE-403049.
  25  * Rewritten for Linux by:
  26  *   Rohan Puri <rohan.puri15@gmail.com>
  27  *   Brian Behlendorf <behlendorf1@llnl.gov>
  28  */
  29
  30 #include <sys/zfs_vfsops.h>
  31 #include <sys/zfs_vnops.h>
  32 #include <sys/zfs_znode.h>
  33 #include <sys/zfs_ctldir.h>
  34 #include <sys/zpl.h>
  35
  36 /*
  37  * Common open routine.  Disallow any write access.
  38  */
  39 /* ARGSUSED */
  40 static int
  41 zpl_common_open(struct inode *ip, struct file *filp)
  42 {
  43         if (filp->f_mode & FMODE_WRITE)
  44                 return (-EACCES);
  45
  46         return generic_file_open(ip, filp);
  47 }
  48
  49 static int
  50 zpl_common_readdir(struct file *filp, void *dirent, filldir_t filldir)
  51 {
  52         struct dentry *dentry = filp->f_path.dentry;
  53         struct inode *ip = dentry->d_inode;
  54         int error = 0;
  55
  56         switch (filp->f_pos) {
  57         case 0:
  58                 error = filldir(dirent, ".", 1, 0, ip->i_ino, DT_DIR);
  59                 if (error)
  60                         break;
  61
  62                 filp->f_pos++;
  63                 /* fall-thru */
  64         case 1:
  65                 error = filldir(dirent, "..", 2, 1, parent_ino(dentry), DT_DIR);
  66                 if (error)
  67                         break;
  68
  69                 filp->f_pos++;
  70                 /* fall-thru */
  71         default:
  72                 break;
  73         }
  74
  75         return (error);
  76 }
  77
  78 /*
  79  * Get root directory contents.
  80  */
  81 static int
  82 zpl_root_readdir(struct file *filp, void *dirent, filldir_t filldir)
  83 {
  84         struct dentry *dentry = filp->f_path.dentry;
  85         struct inode *ip = dentry->d_inode;
  86         zfs_sb_t *zsb = ITOZSB(ip);
  87         int error = 0;
  88
  89         ZFS_ENTER(zsb);
  90
  91         switch (filp->f_pos) {
  92         case 0:
  93                 error = filldir(dirent, ".", 1, 0, ip->i_ino, DT_DIR);
  94                 if (error)
  95                         goto out;
  96
  97                 filp->f_pos++;
  98                 /* fall-thru */
  99         case 1:
 100                 error = filldir(dirent, "..", 2, 1, parent_ino(dentry), DT_DIR);
 101                 if (error)
 102                         goto out;
 103
 104                 filp->f_pos++;
 105                 /* fall-thru */
 106         case 2:
 107                 error = filldir(dirent, ZFS_SNAPDIR_NAME,
 108                     strlen(ZFS_SNAPDIR_NAME), 2, ZFSCTL_INO_SNAPDIR, DT_DIR);
 109                 if (error)
 110                         goto out;
 111
 112                 filp->f_pos++;
 113                 /* fall-thru */
 114         case 3:
 115                 error = filldir(dirent, ZFS_SHAREDIR_NAME,
 116                     strlen(ZFS_SHAREDIR_NAME), 3, ZFSCTL_INO_SHARES, DT_DIR);
 117                 if (error)
 118                         goto out;
 119
 120                 filp->f_pos++;
 121                 /* fall-thru */
 122         }
 123 out:
 124         ZFS_EXIT(zsb);
 125
 126         return (error);
 127 }
 128
 129 /*
 130  * Get root directory attributes.
 131  */
 132 /* ARGSUSED */
 133 static int
 134 zpl_root_getattr(struct vfsmount *mnt, struct dentry *dentry,
 135     struct kstat *stat)
 136 {
 137         int error;
 138
 139         error = simple_getattr(mnt, dentry, stat);
 140         stat->atime = CURRENT_TIME;
 141
 142         return (error);
 143 }
 144
 145 static struct dentry *
 146 #ifdef HAVE_LOOKUP_NAMEIDATA
 147 zpl_root_lookup(struct inode *dip, struct dentry *dentry, struct nameidata *nd)
 148 #else
 149 zpl_root_lookup(struct inode *dip, struct dentry *dentry, unsigned int flags)
 150 #endif
 151 {
 152         cred_t *cr = CRED();
 153         struct inode *ip;
 154         int error;
 155
 156         crhold(cr);
 157         error = -zfsctl_root_lookup(dip, dname(dentry), &ip, 0, cr, NULL, NULL);
 158         ASSERT3S(error, <=, 0);
 159         crfree(cr);
 160
 161         if (error) {
 162                 if (error == -ENOENT)
 163                         return d_splice_alias(NULL, dentry);
 164                 else
 165                         return ERR_PTR(error);
 166         }
 167
 168         return d_splice_alias(ip, dentry);
 169 }
 170
 171 /*
 172  * The '.zfs' control directory file and inode operations.
 173  */
 174 const struct file_operations zpl_fops_root = {
 175         .open           = zpl_common_open,
 176         .llseek         = generic_file_llseek,
 177         .read           = generic_read_dir,
 178         .readdir        = zpl_root_readdir,
 179 };
 180
 181 const struct inode_operations zpl_ops_root = {
 182         .lookup         = zpl_root_lookup,
 183         .getattr        = zpl_root_getattr,
 184 };
 185
 186 static struct dentry *
 187 #ifdef HAVE_LOOKUP_NAMEIDATA
 188 zpl_snapdir_lookup(struct inode *dip, struct dentry *dentry,
 189     struct nameidata *nd)
 190 #else
 191 zpl_snapdir_lookup(struct inode *dip, struct dentry *dentry,
 192     unsigned int flags)
 193 #endif
 194
 195 {
 196         cred_t *cr = CRED();
 197         struct inode *ip;
 198         int error;
 199
 200         crhold(cr);
 201         error = -zfsctl_snapdir_lookup(dip, dname(dentry), &ip,
 202             0, cr, NULL, NULL);
 203         ASSERT3S(error, <=, 0);
 204         crfree(cr);
 205
 206         if (error) {
 207                 if (error == -ENOENT)
 208                         return d_splice_alias(NULL, dentry);
 209                 else
 210                         return ERR_PTR(error);
 211         }
 212
 213         /*
 214          * Auto mounting of snapshots is only supported for 2.6.37 and
 215          * newer kernels.  Prior to this kernel the ops->follow_link()
 216          * callback was used as a hack to trigger the mount.  The
 217          * resulting vfsmount was then explicitly grafted in to the
 218          * name space.  While it might be possible to add compatibility
 219          * code to accomplish this it would require considerable care.
 220          */
 221 #ifdef HAVE_AUTOMOUNT
 222         dentry->d_op = &zpl_dops_snapdirs;
 223 #endif /* HAVE_AUTOMOUNT */
 224
 225         return d_splice_alias(ip, dentry);
 226 }
 227
 228 /* ARGSUSED */
 229 static int
 230 zpl_snapdir_readdir(struct file *filp, void *dirent, filldir_t filldir)
 231 {
 232         struct dentry *dentry = filp->f_path.dentry;
 233         struct inode *dip = dentry->d_inode;
 234         zfs_sb_t *zsb = ITOZSB(dip);
 235         char snapname[MAXNAMELEN];
 236         uint64_t id, cookie;
 237         boolean_t case_conflict;
 238         int error = 0;
 239
 240         ZFS_ENTER(zsb);
 241
 242         cookie = filp->f_pos;
 243         switch (filp->f_pos) {
 244         case 0:
 245                 error = filldir(dirent, ".", 1, 0, dip->i_ino, DT_DIR);
 246                 if (error)
 247                         goto out;
 248
 249                 filp->f_pos++;
 250                 /* fall-thru */
 251         case 1:
 252                 error = filldir(dirent, "..", 2, 1, parent_ino(dentry), DT_DIR);
 253                 if (error)
 254                         goto out;
 255
 256                 filp->f_pos++;
 257                 /* fall-thru */
 258         default:
 259                 while (error == 0) {
 260                         error = -dmu_snapshot_list_next(zsb->z_os, MAXNAMELEN,
 261                             snapname, &id, &cookie, &case_conflict);
 262                         if (error)
 263                                 goto out;
 264
 265                         error = filldir(dirent, snapname, strlen(snapname),
 266                             filp->f_pos, ZFSCTL_INO_SHARES - id, DT_DIR);
 267                         if (error)
 268                                 goto out;
 269
 270                         filp->f_pos = cookie;
 271                 }
 272         }
 273 out:
 274         ZFS_EXIT(zsb);
 275
 276         if (error == -ENOENT)
 277                 return (0);
 278
 279         return (error);
 280 }
 281
 282 int
 283 zpl_snapdir_rename(struct inode *sdip, struct dentry *sdentry,
 284     struct inode *tdip, struct dentry *tdentry)
 285 {
 286         cred_t *cr = CRED();
 287         int error;
 288
 289         crhold(cr);
 290         error = -zfsctl_snapdir_rename(sdip, dname(sdentry),
 291             tdip, dname(tdentry), cr, 0);
 292         ASSERT3S(error, <=, 0);
 293         crfree(cr);
 294
 295         return (error);
 296 }
 297
 298 static int
 299 zpl_snapdir_rmdir(struct inode *dip, struct dentry *dentry)
 300 {
 301         cred_t *cr = CRED();
 302         int error;
 303
 304         crhold(cr);
 305         error = -zfsctl_snapdir_remove(dip, dname(dentry), cr, 0);
 306         ASSERT3S(error, <=, 0);
 307         crfree(cr);
 308
 309         return (error);
 310 }
 311
 312 static int
 313 zpl_snapdir_mkdir(struct inode *dip, struct dentry *dentry, zpl_umode_t mode)
 314 {
 315         cred_t *cr = CRED();
 316         vattr_t *vap;
 317         struct inode *ip;
 318         int error;
 319
 320         crhold(cr);
 321         vap = kmem_zalloc(sizeof(vattr_t), KM_SLEEP);
 322         zpl_vap_init(vap, dip, dentry, mode | S_IFDIR, cr);
 323
 324         error = -zfsctl_snapdir_mkdir(dip, dname(dentry), vap, &ip, cr, 0);
 325         if (error == 0) {
 326 #ifdef HAVE_AUTOMOUNT
 327                 dentry->d_op = &zpl_dops_snapdirs;
 328 #endif /* HAVE_AUTOMOUNT */
 329                 d_instantiate(dentry, ip);
 330         }
 331
 332         kmem_free(vap, sizeof(vattr_t));
 333         ASSERT3S(error, <=, 0);
 334         crfree(cr);
 335
 336         return (error);
 337 }
 338
 339 #ifdef HAVE_AUTOMOUNT
 340 static struct vfsmount *
 341 zpl_snapdir_automount(struct path *path)
 342 {
 343         struct dentry *dentry = path->dentry;
 344         int error;
 345
 346         /*
 347          * We must briefly disable automounts for this dentry because the
 348          * user space mount utility will trigger another lookup on this
 349          * directory.  That will result in zpl_snapdir_automount() being
 350          * called repeatedly.  The DCACHE_NEED_AUTOMOUNT flag can be
 351          * safely reset once the mount completes.
 352          */
 353         dentry->d_flags &= ~DCACHE_NEED_AUTOMOUNT;
 354         error = -zfsctl_mount_snapshot(path, 0);
 355         dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
 356         if (error)
 357                 return ERR_PTR(error);
 358
 359         /*
 360          * Ensure path->dentry points to the dentry for the root of the
 361          * newly-mounted snapshot, otherwise this function may be called
 362          * repeatedly which can lead to an incorrect ELOOP error return.
 363          */
 364         follow_up(path);
 365
 366         /*
 367          * Rather than returning the new vfsmount for the snapshot we must
 368          * return NULL to indicate a mount collision.  This is done because
 369          * the user space mount calls do_add_mount() which adds the vfsmount
 370          * to the name space.  If we returned the new mount here it would be
 371          * added again to the vfsmount list resulting in list corruption.
 372          */
 373         return (NULL);
 374 }
 375 #endif /* HAVE_AUTOMOUNT */
 376
 377 /*
 378  * Get snapshot directory attributes.
 379  */
 380 /* ARGSUSED */
 381 static int
 382 zpl_snapdir_getattr(struct vfsmount *mnt, struct dentry *dentry,
 383     struct kstat *stat)
 384 {
 385         zfs_sb_t *zsb = ITOZSB(dentry->d_inode);
 386         int error;
 387
 388         ZFS_ENTER(zsb);
 389         error = simple_getattr(mnt, dentry, stat);
 390         stat->nlink = stat->size = avl_numnodes(&zsb->z_ctldir_snaps) + 2;
 391         stat->ctime = stat->mtime = dmu_objset_snap_cmtime(zsb->z_os);
 392         stat->atime = CURRENT_TIME;
 393         ZFS_EXIT(zsb);
 394
 395         return (error);
 396 }
 397
 398 /*
 399  * The '.zfs/snapshot' directory file operations.  These mainly control
 400  * generating the list of available snapshots when doing an 'ls' in the
 401  * directory.  See zpl_snapdir_readdir().
 402  */
 403 const struct file_operations zpl_fops_snapdir = {
 404         .open           = zpl_common_open,
 405         .llseek         = generic_file_llseek,
 406         .read           = generic_read_dir,
 407         .readdir        = zpl_snapdir_readdir,
 408 };
 409
 410 /*
 411  * The '.zfs/snapshot' directory inode operations.  These mainly control
 412  * creating an inode for a snapshot directory and initializing the needed
 413  * infrastructure to automount the snapshot.  See zpl_snapdir_lookup().
 414  */
 415 const struct inode_operations zpl_ops_snapdir = {
 416         .lookup         = zpl_snapdir_lookup,
 417         .getattr        = zpl_snapdir_getattr,
 418         .rename         = zpl_snapdir_rename,
 419         .rmdir          = zpl_snapdir_rmdir,
 420         .mkdir          = zpl_snapdir_mkdir,
 421 };
 422
 423 #ifdef HAVE_AUTOMOUNT
 424 const struct dentry_operations zpl_dops_snapdirs = {
 425         .d_automount    = zpl_snapdir_automount,
 426 };
 427 #endif /* HAVE_AUTOMOUNT */
 428
 429 static struct dentry *
 430 #ifdef HAVE_LOOKUP_NAMEIDATA
 431 zpl_shares_lookup(struct inode *dip, struct dentry *dentry,
 432     struct nameidata *nd)
 433 #else
 434 zpl_shares_lookup(struct inode *dip, struct dentry *dentry,
 435     unsigned int flags)
 436 #endif
 437 {
 438         cred_t *cr = CRED();
 439         struct inode *ip = NULL;
 440         int error;
 441
 442         crhold(cr);
 443         error = -zfsctl_shares_lookup(dip, dname(dentry), &ip,
 444             0, cr, NULL, NULL);
 445         ASSERT3S(error, <=, 0);
 446         crfree(cr);
 447
 448         if (error) {
 449                 if (error == -ENOENT)
 450                         return d_splice_alias(NULL, dentry);
 451                 else
 452                         return ERR_PTR(error);
 453         }
 454
 455         return d_splice_alias(ip, dentry);
 456 }
 457
 458 /* ARGSUSED */
 459 static int
 460 zpl_shares_readdir(struct file *filp, void *dirent, filldir_t filldir)
 461 {
 462         cred_t *cr = CRED();
 463         struct dentry *dentry = filp->f_path.dentry;
 464         struct inode *ip = dentry->d_inode;
 465         zfs_sb_t *zsb = ITOZSB(ip);
 466         znode_t *dzp;
 467         int error;
 468
 469         ZFS_ENTER(zsb);
 470
 471         if (zsb->z_shares_dir == 0) {
 472                 error = zpl_common_readdir(filp, dirent, filldir);
 473                 ZFS_EXIT(zsb);
 474                 return (error);
 475         }
 476
 477         error = -zfs_zget(zsb, zsb->z_shares_dir, &dzp);
 478         if (error) {
 479                 ZFS_EXIT(zsb);
 480                 return (error);
 481         }
 482
 483         crhold(cr);
 484         error = -zfs_readdir(ZTOI(dzp), dirent, filldir, &filp->f_pos, cr);
 485         crfree(cr);
 486
 487         iput(ZTOI(dzp));
 488         ZFS_EXIT(zsb);
 489         ASSERT3S(error, <=, 0);
 490
 491         return (error);
 492 }
 493
 494 /* ARGSUSED */
 495 static int
 496 zpl_shares_getattr(struct vfsmount *mnt, struct dentry *dentry,
 497     struct kstat *stat)
 498 {
 499         struct inode *ip = dentry->d_inode;
 500         zfs_sb_t *zsb = ITOZSB(ip);
 501         znode_t *dzp;
 502         int error;
 503
 504         ZFS_ENTER(zsb);
 505
 506         if (zsb->z_shares_dir == 0) {
 507                 error = simple_getattr(mnt, dentry, stat);
 508                 stat->nlink = stat->size = 2;
 509                 stat->atime = CURRENT_TIME;
 510                 ZFS_EXIT(zsb);
 511                 return (error);
 512         }
 513
 514         error = -zfs_zget(zsb, zsb->z_shares_dir, &dzp);
 515         if (error == 0)
 516                 error = -zfs_getattr_fast(dentry->d_inode, stat);
 517
 518         iput(ZTOI(dzp));
 519         ZFS_EXIT(zsb);
 520         ASSERT3S(error, <=, 0);
 521
 522         return (error);
 523 }
 524
 525 /*
 526  * The '.zfs/shares' directory file operations.
 527  */
 528 const struct file_operations zpl_fops_shares = {
 529         .open           = zpl_common_open,
 530         .llseek         = generic_file_llseek,
 531         .read           = generic_read_dir,
 532         .readdir        = zpl_shares_readdir,
 533 };
 534
 535 /*
 536  * The '.zfs/shares' directory inode operations.
 537  */
 538 const struct inode_operations zpl_ops_shares = {
 539         .lookup         = zpl_shares_lookup,
 540         .getattr        = zpl_shares_getattr,
 541 };