bsd/miscfs/union/union_vfsops.c

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /* Copyright (c) 1995 NeXT Computer, Inc. All Rights Reserved */
  23 /*
  24  * Copyright (c) 1994, 1995 The Regents of the University of California.
  25  * Copyright (c) 1994, 1995 Jan-Simon Pendry.
  26  * All rights reserved.
  27  *
  28  * This code is derived from software donated to Berkeley by
  29  * Jan-Simon Pendry.
  30  *
  31  * Redistribution and use in source and binary forms, with or without
  32  * modification, are permitted provided that the following conditions
  33  * are met:
  34  * 1. Redistributions of source code must retain the above copyright
  35  *    notice, this list of conditions and the following disclaimer.
  36  * 2. Redistributions in binary form must reproduce the above copyright
  37  *    notice, this list of conditions and the following disclaimer in the
  38  *    documentation and/or other materials provided with the distribution.
  39  * 3. All advertising materials mentioning features or use of this software
  40  *    must display the following acknowledgement:
  41  *      This product includes software developed by the University of
  42  *      California, Berkeley and its contributors.
  43  * 4. Neither the name of the University nor the names of its contributors
  44  *    may be used to endorse or promote products derived from this software
  45  *    without specific prior written permission.
  46  *
  47  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  48  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  49  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  50  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  51  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  52  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  53  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  54  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  55  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  56  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  57  * SUCH DAMAGE.
  58  *
  59  *      @(#)union_vfsops.c      8.20 (Berkeley) 5/20/95
  60  */
  61
  62 /*
  63  * Union Layer
  64  */
  65
  66 #include <sys/param.h>
  67 #include <sys/systm.h>
  68 #include <sys/time.h>
  69 #include <sys/types.h>
  70 #include <sys/proc.h>
  71 #include <sys/vnode.h>
  72 #include <sys/mount.h>
  73 #include <sys/namei.h>
  74 #include <sys/malloc.h>
  75 #include <sys/filedesc.h>
  76 #include <sys/queue.h>
  77 #include <miscfs/union/union.h>
  78
  79 /*
  80  * Mount union filesystem
  81  */
  82 int
  83 union_mount(mp, path, data, ndp, p)
  84         struct mount *mp;
  85         char *path;
  86         caddr_t data;
  87         struct nameidata *ndp;
  88         struct proc *p;
  89 {
  90         int error = 0;
  91         struct union_args args;
  92         struct vnode *lowerrootvp = NULLVP;
  93         struct vnode *upperrootvp = NULLVP;
  94         struct union_mount *um = 0;
  95         struct ucred *cred = 0;
  96         struct ucred *scred;
  97         struct vattr va;
  98         char *cp;
  99         int len;
 100         u_int size;
 101
 102 #ifdef UNION_DIAGNOSTIC
 103         printf("union_mount(mp = %x)\n", mp);
 104 #endif
 105
 106         /*
 107          * Update is a no-op
 108          */
 109         if (mp->mnt_flag & MNT_UPDATE) {
 110                 /*
 111                  * Need to provide.
 112                  * 1. a way to convert between rdonly and rdwr mounts.
 113                  * 2. support for nfs exports.
 114                  */
 115                 error = EOPNOTSUPP;
 116                 goto bad;
 117         }
 118
 119         /*
 120          * Get argument
 121          */
 122         if (error = copyin(data, (caddr_t)&args, sizeof(struct union_args)))
 123                 goto bad;
 124
 125         lowerrootvp = mp->mnt_vnodecovered;
 126         VREF(lowerrootvp);
 127
 128         /*
 129          * Find upper node.
 130          */
 131         NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT,
 132                UIO_USERSPACE, args.target, p);
 133
 134         if (error = namei(ndp))
 135                 goto bad;
 136
 137         upperrootvp = ndp->ni_vp;
 138         vrele(ndp->ni_dvp);
 139         ndp->ni_dvp = NULL;
 140
 141         if (upperrootvp->v_type != VDIR) {
 142                 error = EINVAL;
 143                 goto bad;
 144         }
 145
 146 //      um = (struct union_mount *) malloc(sizeof(struct union_mount),
 147 //                              M_UFSMNT, M_WAITOK);    /* XXX */
 148         MALLOC(um, struct union_mount *, sizeof(struct union_mount),
 149                                 M_UFSMNT, M_WAITOK);
 150
 151         /*
 152          * Keep a held reference to the target vnodes.
 153          * They are vrele'd in union_unmount.
 154          *
 155          * Depending on the _BELOW flag, the filesystems are
 156          * viewed in a different order.  In effect, this is the
 157          * same as providing a mount under option to the mount syscall.
 158          */
 159
 160         um->um_op = args.mntflags & UNMNT_OPMASK;
 161         switch (um->um_op) {
 162         case UNMNT_ABOVE:
 163                 um->um_lowervp = lowerrootvp;
 164                 um->um_uppervp = upperrootvp;
 165                 break;
 166
 167         case UNMNT_BELOW:
 168                 um->um_lowervp = upperrootvp;
 169                 um->um_uppervp = lowerrootvp;
 170                 break;
 171
 172         case UNMNT_REPLACE:
 173                 vrele(lowerrootvp);
 174                 lowerrootvp = NULLVP;
 175                 um->um_uppervp = upperrootvp;
 176                 um->um_lowervp = lowerrootvp;
 177                 break;
 178
 179         default:
 180                 error = EINVAL;
 181                 goto bad;
 182         }
 183
 184         /*
 185          * Unless the mount is readonly, ensure that the top layer
 186          * supports whiteout operations
 187          */
 188         if ((mp->mnt_flag & MNT_RDONLY) == 0) {
 189                 error = VOP_WHITEOUT(um->um_uppervp, (struct componentname *) 0, LOOKUP);
 190                 if (error)
 191                         goto bad;
 192         }
 193
 194         um->um_cred = p->p_ucred;
 195         crhold(um->um_cred);
 196         um->um_cmode = UN_DIRMODE &~ p->p_fd->fd_cmask;
 197
 198         /*
 199          * Depending on what you think the MNT_LOCAL flag might mean,
 200          * you may want the && to be || on the conditional below.
 201          * At the moment it has been defined that the filesystem is
 202          * only local if it is all local, ie the MNT_LOCAL flag implies
 203          * that the entire namespace is local.  If you think the MNT_LOCAL
 204          * flag implies that some of the files might be stored locally
 205          * then you will want to change the conditional.
 206          */
 207         if (um->um_op == UNMNT_ABOVE) {
 208                 if (((um->um_lowervp == NULLVP) ||
 209                      (um->um_lowervp->v_mount->mnt_flag & MNT_LOCAL)) &&
 210                     (um->um_uppervp->v_mount->mnt_flag & MNT_LOCAL))
 211                         mp->mnt_flag |= MNT_LOCAL;
 212         }
 213
 214         /*
 215          * Copy in the upper layer's RDONLY flag.  This is for the benefit
 216          * of lookup() which explicitly checks the flag, rather than asking
 217          * the filesystem for it's own opinion.  This means, that an update
 218          * mount of the underlying filesystem to go from rdonly to rdwr
 219          * will leave the unioned view as read-only.
 220          */
 221         mp->mnt_flag |= (um->um_uppervp->v_mount->mnt_flag & MNT_RDONLY);
 222
 223         mp->mnt_data = (qaddr_t) um;
 224         vfs_getnewfsid(mp);
 225
 226         (void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size);
 227         bzero(mp->mnt_stat.f_mntonname + size, MNAMELEN - size);
 228
 229         switch (um->um_op) {
 230         case UNMNT_ABOVE:
 231                 cp = "<above>:";
 232                 break;
 233         case UNMNT_BELOW:
 234                 cp = "<below>:";
 235                 break;
 236         case UNMNT_REPLACE:
 237                 cp = "";
 238                 break;
 239         }
 240         len = strlen(cp);
 241         bcopy(cp, mp->mnt_stat.f_mntfromname, len);
 242
 243         cp = mp->mnt_stat.f_mntfromname + len;
 244         len = MNAMELEN - len;
 245
 246         (void) copyinstr(args.target, cp, len - 1, &size);
 247         bzero(cp + size, len - size);
 248
 249 #ifdef UNION_DIAGNOSTIC
 250         printf("union_mount: from %s, on %s\n",
 251                 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
 252 #endif
 253         return (0);
 254
 255 bad:
 256         if (um)
 257                 _FREE(um, M_UFSMNT);
 258         if (cred != NOCRED)
 259                 crfree(cred);
 260         if (upperrootvp)
 261                 vrele(upperrootvp);
 262         if (lowerrootvp)
 263                 vrele(lowerrootvp);
 264         return (error);
 265 }
 266
 267 /*
 268  * VFS start.  Nothing needed here - the start routine
 269  * on the underlying filesystem(s) will have been called
 270  * when that filesystem was mounted.
 271  */
 272 int
 273 union_start(mp, flags, p)
 274         struct mount *mp;
 275         int flags;
 276         struct proc *p;
 277 {
 278
 279         return (0);
 280 }
 281
 282 /*
 283  * Free reference to union layer
 284  */
 285 int
 286 union_unmount(mp, mntflags, p)
 287         struct mount *mp;
 288         int mntflags;
 289         struct proc *p;
 290 {
 291         struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
 292         struct vnode *um_rootvp;
 293         int error;
 294         int freeing;
 295         int flags = 0;
 296         struct ucred *cred;
 297
 298 #ifdef UNION_DIAGNOSTIC
 299         printf("union_unmount(mp = %x)\n", mp);
 300 #endif
 301
 302         if (mntflags & MNT_FORCE)
 303                 flags |= FORCECLOSE;
 304
 305         if (error = union_root(mp, &um_rootvp))
 306                 return (error);
 307
 308         /*
 309          * Keep flushing vnodes from the mount list.
 310          * This is needed because of the un_pvp held
 311          * reference to the parent vnode.
 312          * If more vnodes have been freed on a given pass,
 313          * the try again.  The loop will iterate at most
 314          * (d) times, where (d) is the maximum tree depth
 315          * in the filesystem.
 316          */
 317         for (freeing = 0; vflush(mp, um_rootvp, flags) != 0;) {
 318                 struct vnode *vp;
 319                 int n;
 320
 321                 /* count #vnodes held on mount list */
 322                 for (n = 0, vp = mp->mnt_vnodelist.lh_first;
 323                                 vp != NULLVP;
 324                                 vp = vp->v_mntvnodes.le_next)
 325                         n++;
 326
 327                 /* if this is unchanged then stop */
 328                 if (n == freeing)
 329                         break;
 330
 331                 /* otherwise try once more time */
 332                 freeing = n;
 333         }
 334
 335         /* At this point the root vnode should have a single reference */
 336         if (um_rootvp->v_usecount > 1) {
 337                 vput(um_rootvp);
 338                 return (EBUSY);
 339         }
 340
 341 #ifdef UNION_DIAGNOSTIC
 342         vprint("union root", um_rootvp);
 343 #endif
 344         /*
 345          * Discard references to upper and lower target vnodes.
 346          */
 347         if (um->um_lowervp)
 348                 vrele(um->um_lowervp);
 349         vrele(um->um_uppervp);
 350         cred = um->um_cred;
 351         if (cred != NOCRED) {
 352                 um->um_cred = NOCRED;
 353                 crfree(cred);
 354         }
 355         /*
 356          * Release reference on underlying root vnode
 357          */
 358         vput(um_rootvp);
 359         /*
 360          * And blow it away for future re-use
 361          */
 362         vgone(um_rootvp);
 363         /*
 364          * Finally, throw away the union_mount structure
 365          */
 366         _FREE(mp->mnt_data, M_UFSMNT);  /* XXX */
 367         mp->mnt_data = 0;
 368         return (0);
 369 }
 370
 371 int
 372 union_root(mp, vpp)
 373         struct mount *mp;
 374         struct vnode **vpp;
 375 {
 376         struct proc *p = current_proc();        /* XXX */
 377         struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
 378         int error;
 379         int loselock;
 380
 381         /*
 382          * Return locked reference to root.
 383          */
 384         VREF(um->um_uppervp);
 385         if ((um->um_op == UNMNT_BELOW) &&
 386              VOP_ISLOCKED(um->um_uppervp)) {
 387                 loselock = 1;
 388         } else {
 389                 vn_lock(um->um_uppervp, LK_EXCLUSIVE | LK_RETRY, p);
 390                 loselock = 0;
 391         }
 392         if (um->um_lowervp)
 393                 VREF(um->um_lowervp);
 394         error = union_allocvp(vpp, mp,
 395                               (struct vnode *) 0,
 396                               (struct vnode *) 0,
 397                               (struct componentname *) 0,
 398                               um->um_uppervp,
 399                               um->um_lowervp,
 400                               1);
 401
 402         if (error) {
 403                 if (loselock)
 404                         vrele(um->um_uppervp);
 405                 else
 406                         vput(um->um_uppervp);
 407                 if (um->um_lowervp)
 408                         vrele(um->um_lowervp);
 409         } else {
 410                 if (loselock)
 411                         VTOUNION(*vpp)->un_flags &= ~UN_ULOCK;
 412         }
 413
 414         return (error);
 415 }
 416
 417 int
 418 union_statfs(mp, sbp, p)
 419         struct mount *mp;
 420         struct statfs *sbp;
 421         struct proc *p;
 422 {
 423         int error;
 424         struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
 425         struct statfs mstat;
 426         int lbsize;
 427
 428 #ifdef UNION_DIAGNOSTIC
 429         printf("union_statfs(mp = %x, lvp = %x, uvp = %x)\n", mp,
 430                         um->um_lowervp,
 431                         um->um_uppervp);
 432 #endif
 433
 434         bzero(&mstat, sizeof(mstat));
 435
 436         if (um->um_lowervp) {
 437                 error = VFS_STATFS(um->um_lowervp->v_mount, &mstat, p);
 438                 if (error)
 439                         return (error);
 440         }
 441
 442         /* now copy across the "interesting" information and fake the rest */
 443 #if 0
 444         sbp->f_type = mstat.f_type;
 445         sbp->f_flags = mstat.f_flags;
 446         sbp->f_bsize = mstat.f_bsize;
 447         sbp->f_iosize = mstat.f_iosize;
 448 #endif
 449         lbsize = mstat.f_bsize;
 450         sbp->f_blocks = mstat.f_blocks;
 451         sbp->f_bfree = mstat.f_bfree;
 452         sbp->f_bavail = mstat.f_bavail;
 453         sbp->f_files = mstat.f_files;
 454         sbp->f_ffree = mstat.f_ffree;
 455
 456         error = VFS_STATFS(um->um_uppervp->v_mount, &mstat, p);
 457         if (error)
 458                 return (error);
 459
 460         sbp->f_flags = mstat.f_flags;
 461         sbp->f_bsize = mstat.f_bsize;
 462         sbp->f_iosize = mstat.f_iosize;
 463
 464         /*
 465          * if the lower and upper blocksizes differ, then frig the
 466          * block counts so that the sizes reported by df make some
 467          * kind of sense.  none of this makes sense though.
 468          */
 469
 470         if (mstat.f_bsize != lbsize)
 471                 sbp->f_blocks = sbp->f_blocks * lbsize / mstat.f_bsize;
 472
 473         /*
 474          * The "total" fields count total resources in all layers,
 475          * the "free" fields count only those resources which are
 476          * free in the upper layer (since only the upper layer
 477          * is writeable).
 478          */
 479         sbp->f_blocks += mstat.f_blocks;
 480         sbp->f_bfree = mstat.f_bfree;
 481         sbp->f_bavail = mstat.f_bavail;
 482         sbp->f_files += mstat.f_files;
 483         sbp->f_ffree = mstat.f_ffree;
 484
 485         if (sbp != &mp->mnt_stat) {
 486                 sbp->f_type = mp->mnt_vfc->vfc_typenum;
 487                 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
 488                 bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN);
 489                 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
 490         }
 491         return (0);
 492 }
 493
 494 /*
 495  * XXX - Assumes no data cached at union layer.
 496  */
 497 #define union_sync ((int (*) __P((struct mount *, int, struct ucred *, \
 498             struct proc *)))nullop)
 499
 500 #define union_fhtovp ((int (*) __P((struct mount *, struct fid *, \
 501             struct mbuf *, struct vnode **, int *, struct ucred **)))eopnotsupp)
 502 int union_init __P((struct vfsconf *));
 503 #define union_quotactl ((int (*) __P((struct mount *, int, uid_t, caddr_t, \
 504             struct proc *)))eopnotsupp)
 505 #define union_sysctl ((int (*) __P((int *, u_int, void *, size_t *, void *, \
 506             size_t, struct proc *)))eopnotsupp)
 507 #define union_vget ((int (*) __P((struct mount *, ino_t, struct vnode **))) \
 508             eopnotsupp)
 509 #define union_vptofh ((int (*) __P((struct vnode *, struct fid *)))eopnotsupp)
 510
 511 struct vfsops union_vfsops = {
 512         union_mount,
 513         union_start,
 514         union_unmount,
 515         union_root,
 516         union_quotactl,
 517         union_statfs,
 518         union_sync,
 519         union_vget,
 520         union_fhtovp,
 521         union_vptofh,
 522         union_init,
 523         union_sysctl,
 524 };