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 /*
  50  * Get root directory contents.
  51  */
  52 static int
  53 zpl_root_iterate(struct file *filp, struct dir_context *ctx)
  54 {
  55         zfs_sb_t *zsb = ITOZSB(filp->f_path.dentry->d_inode);
  56         int error = 0;
  57
  58         ZFS_ENTER(zsb);
  59
  60         if (!dir_emit_dots(filp, ctx))
  61                 goto out;
  62
  63         if (ctx->pos == 2) {
  64                 if (!dir_emit(ctx, ZFS_SNAPDIR_NAME, strlen(ZFS_SNAPDIR_NAME),
  65                     ZFSCTL_INO_SNAPDIR, DT_DIR))
  66                         goto out;
  67
  68                 ctx->pos++;
  69         }
  70
  71         if (ctx->pos == 3) {
  72                 if (!dir_emit(ctx, ZFS_SHAREDIR_NAME, strlen(ZFS_SHAREDIR_NAME),
  73                     ZFSCTL_INO_SHARES, DT_DIR))
  74                         goto out;
  75
  76                 ctx->pos++;
  77         }
  78 out:
  79         ZFS_EXIT(zsb);
  80
  81         return (error);
  82 }
  83
  84 #if !defined(HAVE_VFS_ITERATE)
  85 static int
  86 zpl_root_readdir(struct file *filp, void *dirent, filldir_t filldir)
  87 {
  88         struct dir_context ctx = DIR_CONTEXT_INIT(dirent, filldir, filp->f_pos);
  89         int error;
  90
  91         error = zpl_root_iterate(filp, &ctx);
  92         filp->f_pos = ctx.pos;
  93
  94         return (error);
  95 }
  96 #endif /* HAVE_VFS_ITERATE */
  97
  98 /*
  99  * Get root directory attributes.
 100  */
 101 /* ARGSUSED */
 102 static int
 103 zpl_root_getattr(struct vfsmount *mnt, struct dentry *dentry,
 104     struct kstat *stat)
 105 {
 106         int error;
 107
 108         error = simple_getattr(mnt, dentry, stat);
 109         stat->atime = CURRENT_TIME;
 110
 111         return (error);
 112 }
 113
 114 static struct dentry *
 115 #ifdef HAVE_LOOKUP_NAMEIDATA
 116 zpl_root_lookup(struct inode *dip, struct dentry *dentry, struct nameidata *nd)
 117 #else
 118 zpl_root_lookup(struct inode *dip, struct dentry *dentry, unsigned int flags)
 119 #endif
 120 {
 121         cred_t *cr = CRED();
 122         struct inode *ip;
 123         int error;
 124
 125         crhold(cr);
 126         error = -zfsctl_root_lookup(dip, dname(dentry), &ip, 0, cr, NULL, NULL);
 127         ASSERT3S(error, <=, 0);
 128         crfree(cr);
 129
 130         if (error) {
 131                 if (error == -ENOENT)
 132                         return d_splice_alias(NULL, dentry);
 133                 else
 134                         return ERR_PTR(error);
 135         }
 136
 137         return d_splice_alias(ip, dentry);
 138 }
 139
 140 /*
 141  * The '.zfs' control directory file and inode operations.
 142  */
 143 const struct file_operations zpl_fops_root = {
 144         .open           = zpl_common_open,
 145         .llseek         = generic_file_llseek,
 146         .read           = generic_read_dir,
 147 #ifdef HAVE_VFS_ITERATE
 148         .iterate        = zpl_root_iterate,
 149 #else
 150         .readdir        = zpl_root_readdir,
 151 #endif
 152 };
 153
 154 const struct inode_operations zpl_ops_root = {
 155         .lookup         = zpl_root_lookup,
 156         .getattr        = zpl_root_getattr,
 157 };
 158
 159 #ifdef HAVE_AUTOMOUNT
 160 static struct vfsmount *
 161 zpl_snapdir_automount(struct path *path)
 162 {
 163         struct dentry *dentry = path->dentry;
 164         int error;
 165
 166         /*
 167          * We must briefly disable automounts for this dentry because the
 168          * user space mount utility will trigger another lookup on this
 169          * directory.  That will result in zpl_snapdir_automount() being
 170          * called repeatedly.  The DCACHE_NEED_AUTOMOUNT flag can be
 171          * safely reset once the mount completes.
 172          */
 173         dentry->d_flags &= ~DCACHE_NEED_AUTOMOUNT;
 174         error = -zfsctl_mount_snapshot(path, 0);
 175         dentry->d_flags |= DCACHE_NEED_AUTOMOUNT;
 176         if (error)
 177                 return ERR_PTR(error);
 178
 179         /*
 180          * Rather than returning the new vfsmount for the snapshot we must
 181          * return NULL to indicate a mount collision.  This is done because
 182          * the user space mount calls do_add_mount() which adds the vfsmount
 183          * to the name space.  If we returned the new mount here it would be
 184          * added again to the vfsmount list resulting in list corruption.
 185          */
 186         return (NULL);
 187 }
 188 #endif /* HAVE_AUTOMOUNT */
 189
 190 /*
 191  * Revalidate any dentry in the snapshot directory on lookup, since a snapshot
 192  * having the same name have been created or destroyed since it was cached.
 193  */
 194 static int
 195 #ifdef HAVE_D_REVALIDATE_NAMEIDATA
 196 zpl_snapdir_revalidate(struct dentry *dentry, struct nameidata *i)
 197 #else
 198 zpl_snapdir_revalidate(struct dentry *dentry, unsigned int flags)
 199 #endif
 200 {
 201         return 0;
 202 }
 203
 204 dentry_operations_t zpl_dops_snapdirs = {
 205 /*
 206  * Auto mounting of snapshots is only supported for 2.6.37 and
 207  * newer kernels.  Prior to this kernel the ops->follow_link()
 208  * callback was used as a hack to trigger the mount.  The
 209  * resulting vfsmount was then explicitly grafted in to the
 210  * name space.  While it might be possible to add compatibility
 211  * code to accomplish this it would require considerable care.
 212  */
 213 #ifdef HAVE_AUTOMOUNT
 214         .d_automount    = zpl_snapdir_automount,
 215 #endif /* HAVE_AUTOMOUNT */
 216         .d_revalidate   = zpl_snapdir_revalidate,
 217 };
 218
 219 static struct dentry *
 220 #ifdef HAVE_LOOKUP_NAMEIDATA
 221 zpl_snapdir_lookup(struct inode *dip, struct dentry *dentry,
 222     struct nameidata *nd)
 223 #else
 224 zpl_snapdir_lookup(struct inode *dip, struct dentry *dentry,
 225     unsigned int flags)
 226 #endif
 227
 228 {
 229         cred_t *cr = CRED();
 230         struct inode *ip = NULL;
 231         int error;
 232
 233         crhold(cr);
 234         error = -zfsctl_snapdir_lookup(dip, dname(dentry), &ip,
 235             0, cr, NULL, NULL);
 236         ASSERT3S(error, <=, 0);
 237         crfree(cr);
 238
 239         if (error && error != -ENOENT)
 240                 return ERR_PTR(error);
 241
 242         ASSERT(error == 0 || ip == NULL);
 243         d_clear_d_op(dentry);
 244         d_set_d_op(dentry, &zpl_dops_snapdirs);
 245
 246         return d_splice_alias(ip, dentry);
 247 }
 248
 249 static int
 250 zpl_snapdir_iterate(struct file *filp, struct dir_context *ctx)
 251 {
 252         zfs_sb_t *zsb = ITOZSB(filp->f_path.dentry->d_inode);
 253         char snapname[MAXNAMELEN];
 254         boolean_t case_conflict;
 255         uint64_t id;
 256         int error = 0;
 257
 258         ZFS_ENTER(zsb);
 259
 260         if (!dir_emit_dots(filp, ctx))
 261                 goto out;
 262
 263         while (error == 0) {
 264                 dsl_pool_config_enter(dmu_objset_pool(zsb->z_os), FTAG);
 265                 error = -dmu_snapshot_list_next(zsb->z_os, MAXNAMELEN,
 266                     snapname, &id, &ctx->pos, &case_conflict);
 267                 dsl_pool_config_exit(dmu_objset_pool(zsb->z_os), FTAG);
 268                 if (error)
 269                         goto out;
 270
 271                 if (!dir_emit(ctx, snapname, strlen(snapname),
 272                     ZFSCTL_INO_SHARES - id, DT_DIR))
 273                         goto out;
 274         }
 275 out:
 276         ZFS_EXIT(zsb);
 277
 278         if (error == -ENOENT)
 279                 return (0);
 280
 281         return (error);
 282 }
 283
 284 #if !defined(HAVE_VFS_ITERATE)
 285 static int
 286 zpl_snapdir_readdir(struct file *filp, void *dirent, filldir_t filldir)
 287 {
 288         struct dir_context ctx = DIR_CONTEXT_INIT(dirent, filldir, filp->f_pos);
 289         int error;
 290
 291         error = zpl_snapdir_iterate(filp, &ctx);
 292         filp->f_pos = ctx.pos;
 293
 294         return (error);
 295 }
 296 #endif /* HAVE_VFS_ITERATE */
 297
 298 int
 299 zpl_snapdir_rename(struct inode *sdip, struct dentry *sdentry,
 300     struct inode *tdip, struct dentry *tdentry)
 301 {
 302         cred_t *cr = CRED();
 303         int error;
 304
 305         crhold(cr);
 306         error = -zfsctl_snapdir_rename(sdip, dname(sdentry),
 307             tdip, dname(tdentry), cr, 0);
 308         ASSERT3S(error, <=, 0);
 309         crfree(cr);
 310
 311         return (error);
 312 }
 313
 314 static int
 315 zpl_snapdir_rmdir(struct inode *dip, struct dentry *dentry)
 316 {
 317         cred_t *cr = CRED();
 318         int error;
 319
 320         crhold(cr);
 321         error = -zfsctl_snapdir_remove(dip, dname(dentry), cr, 0);
 322         ASSERT3S(error, <=, 0);
 323         crfree(cr);
 324
 325         return (error);
 326 }
 327
 328 static int
 329 zpl_snapdir_mkdir(struct inode *dip, struct dentry *dentry, zpl_umode_t mode)
 330 {
 331         cred_t *cr = CRED();
 332         vattr_t *vap;
 333         struct inode *ip;
 334         int error;
 335
 336         crhold(cr);
 337         vap = kmem_zalloc(sizeof(vattr_t), KM_SLEEP);
 338         zpl_vap_init(vap, dip, mode | S_IFDIR, cr);
 339
 340         error = -zfsctl_snapdir_mkdir(dip, dname(dentry), vap, &ip, cr, 0);
 341         if (error == 0) {
 342                 d_clear_d_op(dentry);
 343                 d_set_d_op(dentry, &zpl_dops_snapdirs);
 344                 d_instantiate(dentry, ip);
 345         }
 346
 347         kmem_free(vap, sizeof(vattr_t));
 348         ASSERT3S(error, <=, 0);
 349         crfree(cr);
 350
 351         return (error);
 352 }
 353
 354 /*
 355  * Get snapshot directory attributes.
 356  */
 357 /* ARGSUSED */
 358 static int
 359 zpl_snapdir_getattr(struct vfsmount *mnt, struct dentry *dentry,
 360     struct kstat *stat)
 361 {
 362         zfs_sb_t *zsb = ITOZSB(dentry->d_inode);
 363         int error;
 364
 365         ZFS_ENTER(zsb);
 366         error = simple_getattr(mnt, dentry, stat);
 367         stat->nlink = stat->size = avl_numnodes(&zsb->z_ctldir_snaps) + 2;
 368         stat->ctime = stat->mtime = dmu_objset_snap_cmtime(zsb->z_os);
 369         stat->atime = CURRENT_TIME;
 370         ZFS_EXIT(zsb);
 371
 372         return (error);
 373 }
 374
 375 /*
 376  * The '.zfs/snapshot' directory file operations.  These mainly control
 377  * generating the list of available snapshots when doing an 'ls' in the
 378  * directory.  See zpl_snapdir_readdir().
 379  */
 380 const struct file_operations zpl_fops_snapdir = {
 381         .open           = zpl_common_open,
 382         .llseek         = generic_file_llseek,
 383         .read           = generic_read_dir,
 384 #ifdef HAVE_VFS_ITERATE
 385         .iterate        = zpl_snapdir_iterate,
 386 #else
 387         .readdir        = zpl_snapdir_readdir,
 388 #endif
 389
 390 };
 391
 392 /*
 393  * The '.zfs/snapshot' directory inode operations.  These mainly control
 394  * creating an inode for a snapshot directory and initializing the needed
 395  * infrastructure to automount the snapshot.  See zpl_snapdir_lookup().
 396  */
 397 const struct inode_operations zpl_ops_snapdir = {
 398         .lookup         = zpl_snapdir_lookup,
 399         .getattr        = zpl_snapdir_getattr,
 400         .rename         = zpl_snapdir_rename,
 401         .rmdir          = zpl_snapdir_rmdir,
 402         .mkdir          = zpl_snapdir_mkdir,
 403 };
 404
 405 static struct dentry *
 406 #ifdef HAVE_LOOKUP_NAMEIDATA
 407 zpl_shares_lookup(struct inode *dip, struct dentry *dentry,
 408     struct nameidata *nd)
 409 #else
 410 zpl_shares_lookup(struct inode *dip, struct dentry *dentry,
 411     unsigned int flags)
 412 #endif
 413 {
 414         cred_t *cr = CRED();
 415         struct inode *ip = NULL;
 416         int error;
 417
 418         crhold(cr);
 419         error = -zfsctl_shares_lookup(dip, dname(dentry), &ip,
 420             0, cr, NULL, NULL);
 421         ASSERT3S(error, <=, 0);
 422         crfree(cr);
 423
 424         if (error) {
 425                 if (error == -ENOENT)
 426                         return d_splice_alias(NULL, dentry);
 427                 else
 428                         return ERR_PTR(error);
 429         }
 430
 431         return d_splice_alias(ip, dentry);
 432 }
 433
 434 static int
 435 zpl_shares_iterate(struct file *filp, struct dir_context *ctx)
 436 {
 437         cred_t *cr = CRED();
 438         zfs_sb_t *zsb = ITOZSB(filp->f_path.dentry->d_inode);
 439         znode_t *dzp;
 440         int error = 0;
 441
 442         ZFS_ENTER(zsb);
 443
 444         if (zsb->z_shares_dir == 0) {
 445                 dir_emit_dots(filp, ctx);
 446                 goto out;
 447         }
 448
 449         error = -zfs_zget(zsb, zsb->z_shares_dir, &dzp);
 450         if (error)
 451                 goto out;
 452
 453         crhold(cr);
 454         error = -zfs_readdir(ZTOI(dzp), ctx, cr);
 455         crfree(cr);
 456
 457         iput(ZTOI(dzp));
 458 out:
 459         ZFS_EXIT(zsb);
 460         ASSERT3S(error, <=, 0);
 461
 462         return (error);
 463 }
 464
 465 #if !defined(HAVE_VFS_ITERATE)
 466 static int
 467 zpl_shares_readdir(struct file *filp, void *dirent, filldir_t filldir)
 468 {
 469         struct dir_context ctx = DIR_CONTEXT_INIT(dirent, filldir, filp->f_pos);
 470         int error;
 471
 472         error = zpl_shares_iterate(filp, &ctx);
 473         filp->f_pos = ctx.pos;
 474
 475         return (error);
 476 }
 477 #endif /* HAVE_VFS_ITERATE */
 478
 479 /* ARGSUSED */
 480 static int
 481 zpl_shares_getattr(struct vfsmount *mnt, struct dentry *dentry,
 482     struct kstat *stat)
 483 {
 484         struct inode *ip = dentry->d_inode;
 485         zfs_sb_t *zsb = ITOZSB(ip);
 486         znode_t *dzp;
 487         int error;
 488
 489         ZFS_ENTER(zsb);
 490
 491         if (zsb->z_shares_dir == 0) {
 492                 error = simple_getattr(mnt, dentry, stat);
 493                 stat->nlink = stat->size = 2;
 494                 stat->atime = CURRENT_TIME;
 495                 ZFS_EXIT(zsb);
 496                 return (error);
 497         }
 498
 499         error = -zfs_zget(zsb, zsb->z_shares_dir, &dzp);
 500         if (error == 0) {
 501                 error = -zfs_getattr_fast(ZTOI(dzp), stat);
 502                 iput(ZTOI(dzp));
 503         }
 504
 505         ZFS_EXIT(zsb);
 506         ASSERT3S(error, <=, 0);
 507
 508         return (error);
 509 }
 510
 511 /*
 512  * The '.zfs/shares' directory file operations.
 513  */
 514 const struct file_operations zpl_fops_shares = {
 515         .open           = zpl_common_open,
 516         .llseek         = generic_file_llseek,
 517         .read           = generic_read_dir,
 518 #ifdef HAVE_VFS_ITERATE
 519         .iterate        = zpl_shares_iterate,
 520 #else
 521         .readdir        = zpl_shares_readdir,
 522 #endif
 523
 524 };
 525
 526 /*
 527  * The '.zfs/shares' directory inode operations.
 528  */
 529 const struct inode_operations zpl_ops_shares = {
 530         .lookup         = zpl_shares_lookup,
 531         .getattr        = zpl_shares_getattr,
 532 };