Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/fs/unionfs/union_vfsops.c
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1 /*- 2 * Copyright (c) 1994, 1995 The Regents of the University of California. 3 * Copyright (c) 1994, 1995 Jan-Simon Pendry. 4 * All rights reserved. 5 * 6 * This code is derived from software donated to Berkeley by 7 * Jan-Simon Pendry. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)union_vfsops.c 8.20 (Berkeley) 5/20/95 34 * $FreeBSD: releng/6.1/sys/fs/unionfs/union_vfsops.c 145586 2005-04-27 09:07:13Z jeff $ 35 */ 36 37 /* 38 * Union Layer 39 */ 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/kernel.h> 44 #include <sys/lock.h> 45 #include <sys/mutex.h> 46 #include <sys/proc.h> 47 #include <sys/vnode.h> 48 #include <sys/mount.h> 49 #include <sys/namei.h> 50 #include <sys/malloc.h> 51 #include <sys/filedesc.h> 52 #include <fs/unionfs/union.h> 53 54 static MALLOC_DEFINE(M_UNIONFSMNT, "UNION mount", "UNION mount structure"); 55 56 extern vfs_init_t union_init; 57 static vfs_root_t union_root; 58 static vfs_mount_t union_mount; 59 static vfs_statfs_t union_statfs; 60 static vfs_unmount_t union_unmount; 61 62 /* 63 * Mount union filesystem. 64 */ 65 static int 66 union_mount(mp, td) 67 struct mount *mp; 68 struct thread *td; 69 { 70 int error = 0; 71 struct vfsoptlist *opts; 72 struct vnode *lowerrootvp = NULLVP; 73 struct vnode *upperrootvp = NULLVP; 74 struct union_mount *um = 0; 75 struct vattr va; 76 char *cp = 0, *target; 77 int op; 78 int len; 79 size_t size; 80 struct componentname fakecn; 81 struct nameidata nd, *ndp = &nd; 82 83 UDEBUG(("union_mount(mp = %p)\n", (void *)mp)); 84 85 opts = mp->mnt_optnew; 86 /* 87 * Disable clustered write, otherwise system becomes unstable. 88 */ 89 mp->mnt_flag |= MNT_NOCLUSTERW; 90 91 if (mp->mnt_flag & MNT_ROOTFS) 92 return (EOPNOTSUPP); 93 /* 94 * Update is a no-op 95 */ 96 if (mp->mnt_flag & MNT_UPDATE) 97 /* 98 * Need to provide: 99 * 1. a way to convert between rdonly and rdwr mounts. 100 * 2. support for nfs exports. 101 */ 102 return (EOPNOTSUPP); 103 104 /* 105 * Get arguments. 106 */ 107 error = vfs_getopt(opts, "target", (void **)&target, &len); 108 if (error || target[len - 1] != '\0') 109 return (EINVAL); 110 111 op = 0; 112 if (vfs_getopt(opts, "below", NULL, NULL) == 0) 113 op = UNMNT_BELOW; 114 if (vfs_getopt(opts, "replace", NULL, NULL) == 0) { 115 /* These options are mutually exclusive. */ 116 if (op) 117 return (EINVAL); 118 op = UNMNT_REPLACE; 119 } 120 /* 121 * UNMNT_ABOVE is the default. 122 */ 123 if (op == 0) 124 op = UNMNT_ABOVE; 125 126 /* 127 * Obtain lower vnode. Vnode is stored in mp->mnt_vnodecovered. 128 * We need to reference it but not lock it. 129 */ 130 lowerrootvp = mp->mnt_vnodecovered; 131 VREF(lowerrootvp); 132 /* 133 * Obtain upper vnode by calling namei() on the path. The 134 * upperrootvp will be turned referenced and locked. 135 */ 136 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, td); 137 error = namei(ndp); 138 if (error) 139 goto bad; 140 NDFREE(ndp, NDF_ONLY_PNBUF); 141 upperrootvp = ndp->ni_vp; 142 143 UDEBUG(("mount_root UPPERVP %p locked = %d\n", upperrootvp, 144 VOP_ISLOCKED(upperrootvp, NULL))); 145 146 /* 147 * Check multi union mount to avoid `lock myself again' panic. 148 * Also require that it be a directory. 149 */ 150 if (upperrootvp == VTOUNION(lowerrootvp)->un_uppervp) { 151 #ifdef DIAGNOSTIC 152 printf("union_mount: multi union mount?\n"); 153 #endif 154 error = EDEADLK; 155 goto bad; 156 } 157 158 if (upperrootvp->v_type != VDIR) { 159 error = EINVAL; 160 goto bad; 161 } 162 163 /* 164 * Allocate our union_mount structure and populate the fields. 165 * The vnode references are stored in the union_mount as held, 166 * unlocked references. Depending on the _BELOW flag, the 167 * filesystems are viewed in a different order. In effect this 168 * is the same as providing a mount-under option to the mount 169 * syscall. 170 */ 171 172 um = (struct union_mount *) malloc(sizeof(struct union_mount), 173 M_UNIONFSMNT, M_WAITOK | M_ZERO); 174 175 um->um_op = op; 176 177 error = VOP_GETATTR(upperrootvp, &va, td->td_ucred, td); 178 if (error) 179 goto bad; 180 181 um->um_upperdev = va.va_fsid; 182 183 switch (um->um_op) { 184 case UNMNT_ABOVE: 185 um->um_lowervp = lowerrootvp; 186 um->um_uppervp = upperrootvp; 187 upperrootvp = NULL; 188 lowerrootvp = NULL; 189 break; 190 191 case UNMNT_BELOW: 192 VOP_UNLOCK(upperrootvp, 0, td); 193 vn_lock(lowerrootvp, LK_RETRY|LK_EXCLUSIVE, td); 194 um->um_lowervp = upperrootvp; 195 um->um_uppervp = lowerrootvp; 196 upperrootvp = NULL; 197 lowerrootvp = NULL; 198 break; 199 200 case UNMNT_REPLACE: 201 vrele(lowerrootvp); 202 lowerrootvp = NULL; 203 um->um_uppervp = upperrootvp; 204 um->um_lowervp = lowerrootvp; 205 upperrootvp = NULL; 206 break; 207 208 default: 209 error = EINVAL; 210 goto bad; 211 } 212 213 /* 214 * Unless the mount is readonly, ensure that the top layer 215 * supports whiteout operations. 216 */ 217 if ((mp->mnt_flag & MNT_RDONLY) == 0) { 218 /* 219 * XXX Fake up a struct componentname with only cn_nameiop 220 * and cn_thread valid; union_whiteout() needs to use the 221 * thread pointer to lock the vnode. 222 */ 223 bzero(&fakecn, sizeof(fakecn)); 224 fakecn.cn_nameiop = LOOKUP; 225 fakecn.cn_thread = td; 226 error = VOP_WHITEOUT(um->um_uppervp, &fakecn, LOOKUP); 227 if (error) 228 goto bad; 229 } 230 VOP_UNLOCK(um->um_uppervp, 0, td); 231 232 um->um_cred = crhold(td->td_ucred); 233 FILEDESC_LOCK_FAST(td->td_proc->p_fd); 234 um->um_cmode = UN_DIRMODE &~ td->td_proc->p_fd->fd_cmask; 235 FILEDESC_UNLOCK_FAST(td->td_proc->p_fd); 236 237 /* 238 * Depending on what you think the MNT_LOCAL flag might mean, 239 * you may want the && to be || on the conditional below. 240 * At the moment it has been defined that the filesystem is 241 * only local if it is all local, ie the MNT_LOCAL flag implies 242 * that the entire namespace is local. If you think the MNT_LOCAL 243 * flag implies that some of the files might be stored locally 244 * then you will want to change the conditional. 245 */ 246 if (um->um_op == UNMNT_ABOVE) { 247 if (((um->um_lowervp == NULLVP) || 248 (um->um_lowervp->v_mount->mnt_flag & MNT_LOCAL)) && 249 (um->um_uppervp->v_mount->mnt_flag & MNT_LOCAL)) 250 mp->mnt_flag |= MNT_LOCAL; 251 } 252 253 /* 254 * Copy in the upper layer's RDONLY flag. This is for the benefit 255 * of lookup() which explicitly checks the flag, rather than asking 256 * the filesystem for its own opinion. This means, that an update 257 * mount of the underlying filesystem to go from rdonly to rdwr 258 * will leave the unioned view as read-only. 259 */ 260 mp->mnt_flag |= (um->um_uppervp->v_mount->mnt_flag & MNT_RDONLY); 261 262 mp->mnt_data = (qaddr_t) um; 263 vfs_getnewfsid(mp); 264 265 switch (um->um_op) { 266 case UNMNT_ABOVE: 267 cp = "<above>:"; 268 break; 269 case UNMNT_BELOW: 270 cp = "<below>:"; 271 break; 272 case UNMNT_REPLACE: 273 cp = ""; 274 break; 275 } 276 len = strlen(cp); 277 bcopy(cp, mp->mnt_stat.f_mntfromname, len); 278 279 cp = mp->mnt_stat.f_mntfromname + len; 280 len = MNAMELEN - len; 281 282 (void) copystr(target, cp, len - 1, &size); 283 bzero(cp + size, len - size); 284 285 UDEBUG(("union_mount: from %s, on %s\n", 286 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname)); 287 return (0); 288 289 bad: 290 if (um) { 291 if (um->um_uppervp) 292 vput(um->um_uppervp); 293 if (um->um_lowervp) 294 vrele(um->um_lowervp); 295 /* XXX other fields */ 296 free(um, M_UNIONFSMNT); 297 } 298 if (upperrootvp) 299 vput(upperrootvp); 300 if (lowerrootvp) 301 vrele(lowerrootvp); 302 return (error); 303 } 304 305 /* 306 * Free reference to union layer. 307 */ 308 static int 309 union_unmount(mp, mntflags, td) 310 struct mount *mp; 311 int mntflags; 312 struct thread *td; 313 { 314 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 315 int error; 316 int freeing; 317 int flags = 0; 318 319 UDEBUG(("union_unmount(mp = %p)\n", (void *)mp)); 320 321 if (mntflags & MNT_FORCE) 322 flags |= FORCECLOSE; 323 324 /* 325 * Keep flushing vnodes from the mount list. 326 * This is needed because of the un_pvp held 327 * reference to the parent vnode. 328 * If more vnodes have been freed on a given pass, 329 * the try again. The loop will iterate at most 330 * (d) times, where (d) is the maximum tree depth 331 * in the filesystem. 332 */ 333 for (freeing = 0; (error = vflush(mp, 0, flags, td)) != 0;) { 334 int n; 335 336 /* count #vnodes held on mount list */ 337 n = mp->mnt_nvnodelistsize; 338 339 /* if this is unchanged then stop */ 340 if (n == freeing) 341 break; 342 343 /* otherwise try once more time */ 344 freeing = n; 345 } 346 347 /* 348 * If the most recent vflush failed, the filesystem is still busy. 349 */ 350 if (error) 351 return (error); 352 353 /* 354 * Discard references to upper and lower target vnodes. 355 */ 356 if (um->um_lowervp) 357 vrele(um->um_lowervp); 358 vrele(um->um_uppervp); 359 crfree(um->um_cred); 360 /* 361 * Finally, throw away the union_mount structure. 362 */ 363 free(mp->mnt_data, M_UNIONFSMNT); /* XXX */ 364 mp->mnt_data = 0; 365 return (0); 366 } 367 368 static int 369 union_root(mp, flags, vpp, td) 370 struct mount *mp; 371 int flags; 372 struct vnode **vpp; 373 struct thread *td; 374 { 375 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 376 int error; 377 378 /* 379 * Supply an unlocked reference to um_uppervp and to um_lowervp. It 380 * is possible for um_uppervp to be locked without the associated 381 * root union_node being locked. We let union_allocvp() deal with 382 * it. 383 */ 384 UDEBUG(("union_root UPPERVP %p locked = %d\n", um->um_uppervp, 385 VOP_ISLOCKED(um->um_uppervp, NULL))); 386 387 VREF(um->um_uppervp); 388 if (um->um_lowervp) 389 VREF(um->um_lowervp); 390 391 error = union_allocvp(vpp, mp, NULLVP, NULLVP, NULL, 392 um->um_uppervp, um->um_lowervp, 1); 393 UDEBUG(("error %d\n", error)); 394 UDEBUG(("union_root2 UPPERVP %p locked = %d\n", um->um_uppervp, 395 VOP_ISLOCKED(um->um_uppervp, NULL))); 396 397 return (error); 398 } 399 400 static int 401 union_statfs(mp, sbp, td) 402 struct mount *mp; 403 struct statfs *sbp; 404 struct thread *td; 405 { 406 int error; 407 struct union_mount *um = MOUNTTOUNIONMOUNT(mp); 408 struct statfs mstat; 409 int lbsize; 410 411 UDEBUG(("union_statfs(mp = %p, lvp = %p, uvp = %p)\n", 412 (void *)mp, (void *)um->um_lowervp, (void *)um->um_uppervp)); 413 414 bzero(&mstat, sizeof(mstat)); 415 416 if (um->um_lowervp) { 417 error = VFS_STATFS(um->um_lowervp->v_mount, &mstat, td); 418 if (error) 419 return (error); 420 } 421 422 /* 423 * Now copy across the "interesting" information and fake the rest. 424 */ 425 #if 0 426 sbp->f_type = mstat.f_type; 427 sbp->f_flags = mstat.f_flags; 428 sbp->f_bsize = mstat.f_bsize; 429 sbp->f_iosize = mstat.f_iosize; 430 #endif 431 lbsize = mstat.f_bsize; 432 sbp->f_blocks = mstat.f_blocks; 433 sbp->f_bfree = mstat.f_bfree; 434 sbp->f_bavail = mstat.f_bavail; 435 sbp->f_files = mstat.f_files; 436 sbp->f_ffree = mstat.f_ffree; 437 438 error = VFS_STATFS(um->um_uppervp->v_mount, &mstat, td); 439 if (error) 440 return (error); 441 442 sbp->f_flags = mstat.f_flags; 443 sbp->f_bsize = mstat.f_bsize; 444 sbp->f_iosize = mstat.f_iosize; 445 446 /* 447 * If the lower and upper blocksizes differ, then frig the 448 * block counts so that the sizes reported by df make some 449 * kind of sense. None of this makes sense though. 450 */ 451 452 if (mstat.f_bsize != lbsize) 453 sbp->f_blocks = ((off_t) sbp->f_blocks * lbsize) / mstat.f_bsize; 454 455 /* 456 * The "total" fields count total resources in all layers, 457 * the "free" fields count only those resources which are 458 * free in the upper layer (since only the upper layer 459 * is writeable). 460 */ 461 sbp->f_blocks += mstat.f_blocks; 462 sbp->f_bfree = mstat.f_bfree; 463 sbp->f_bavail = mstat.f_bavail; 464 sbp->f_files += mstat.f_files; 465 sbp->f_ffree = mstat.f_ffree; 466 return (0); 467 } 468 469 static struct vfsops union_vfsops = { 470 .vfs_init = union_init, 471 .vfs_mount = union_mount, 472 .vfs_root = union_root, 473 .vfs_statfs = union_statfs, 474 .vfs_unmount = union_unmount, 475 }; 476 477 VFS_SET(union_vfsops, unionfs, VFCF_LOOPBACK);
Cache object: e2e243f9272f4a193e909f8f25db4339
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