Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/fs/fdescfs/fdesc_vnops.c
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1 /*- 2 * Copyright (c) 1992, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software donated to Berkeley by 6 * Jan-Simon Pendry. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)fdesc_vnops.c 8.9 (Berkeley) 1/21/94 33 * 34 * $FreeBSD$ 35 */ 36 37 /* 38 * /dev/fd Filesystem 39 */ 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/capability.h> 44 #include <sys/conf.h> 45 #include <sys/dirent.h> 46 #include <sys/filedesc.h> 47 #include <sys/kernel.h> /* boottime */ 48 #include <sys/lock.h> 49 #include <sys/mutex.h> 50 #include <sys/malloc.h> 51 #include <sys/file.h> /* Must come after sys/malloc.h */ 52 #include <sys/mount.h> 53 #include <sys/namei.h> 54 #include <sys/proc.h> 55 #include <sys/stat.h> 56 #include <sys/vnode.h> 57 58 #include <fs/fdescfs/fdesc.h> 59 60 #define NFDCACHE 4 61 #define FD_NHASH(ix) \ 62 (&fdhashtbl[(ix) & fdhash]) 63 static LIST_HEAD(fdhashhead, fdescnode) *fdhashtbl; 64 static u_long fdhash; 65 66 struct mtx fdesc_hashmtx; 67 68 static vop_getattr_t fdesc_getattr; 69 static vop_lookup_t fdesc_lookup; 70 static vop_open_t fdesc_open; 71 static vop_readdir_t fdesc_readdir; 72 static vop_reclaim_t fdesc_reclaim; 73 static vop_setattr_t fdesc_setattr; 74 75 static struct vop_vector fdesc_vnodeops = { 76 .vop_default = &default_vnodeops, 77 78 .vop_access = VOP_NULL, 79 .vop_getattr = fdesc_getattr, 80 .vop_lookup = fdesc_lookup, 81 .vop_open = fdesc_open, 82 .vop_pathconf = vop_stdpathconf, 83 .vop_readdir = fdesc_readdir, 84 .vop_reclaim = fdesc_reclaim, 85 .vop_setattr = fdesc_setattr, 86 }; 87 88 static void fdesc_insmntque_dtr(struct vnode *, void *); 89 static void fdesc_remove_entry(struct fdescnode *); 90 91 /* 92 * Initialise cache headers 93 */ 94 int 95 fdesc_init(vfsp) 96 struct vfsconf *vfsp; 97 { 98 99 mtx_init(&fdesc_hashmtx, "fdescfs_hash", NULL, MTX_DEF); 100 fdhashtbl = hashinit(NFDCACHE, M_CACHE, &fdhash); 101 return (0); 102 } 103 104 /* 105 * Uninit ready for unload. 106 */ 107 int 108 fdesc_uninit(vfsp) 109 struct vfsconf *vfsp; 110 { 111 112 hashdestroy(fdhashtbl, M_CACHE, fdhash); 113 mtx_destroy(&fdesc_hashmtx); 114 return (0); 115 } 116 117 /* 118 * If allocating vnode fails, call this. 119 */ 120 static void 121 fdesc_insmntque_dtr(struct vnode *vp, void *arg) 122 { 123 124 vgone(vp); 125 vput(vp); 126 } 127 128 /* 129 * Remove an entry from the hash if it exists. 130 */ 131 static void 132 fdesc_remove_entry(struct fdescnode *fd) 133 { 134 struct fdhashhead *fc; 135 struct fdescnode *fd2; 136 137 fc = FD_NHASH(fd->fd_ix); 138 mtx_lock(&fdesc_hashmtx); 139 LIST_FOREACH(fd2, fc, fd_hash) { 140 if (fd == fd2) { 141 LIST_REMOVE(fd, fd_hash); 142 break; 143 } 144 } 145 mtx_unlock(&fdesc_hashmtx); 146 } 147 148 int 149 fdesc_allocvp(ftype, fd_fd, ix, mp, vpp) 150 fdntype ftype; 151 unsigned fd_fd; 152 int ix; 153 struct mount *mp; 154 struct vnode **vpp; 155 { 156 struct fdescmount *fmp; 157 struct fdhashhead *fc; 158 struct fdescnode *fd, *fd2; 159 struct vnode *vp, *vp2; 160 struct thread *td; 161 int error = 0; 162 163 td = curthread; 164 fc = FD_NHASH(ix); 165 loop: 166 mtx_lock(&fdesc_hashmtx); 167 /* 168 * If a forced unmount is progressing, we need to drop it. The flags are 169 * protected by the hashmtx. 170 */ 171 fmp = (struct fdescmount *)mp->mnt_data; 172 if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) { 173 mtx_unlock(&fdesc_hashmtx); 174 return (-1); 175 } 176 177 LIST_FOREACH(fd, fc, fd_hash) { 178 if (fd->fd_ix == ix && fd->fd_vnode->v_mount == mp) { 179 /* Get reference to vnode in case it's being free'd */ 180 vp = fd->fd_vnode; 181 VI_LOCK(vp); 182 mtx_unlock(&fdesc_hashmtx); 183 if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, td)) 184 goto loop; 185 *vpp = vp; 186 return (0); 187 } 188 } 189 mtx_unlock(&fdesc_hashmtx); 190 191 fd = malloc(sizeof(struct fdescnode), M_TEMP, M_WAITOK); 192 193 error = getnewvnode("fdescfs", mp, &fdesc_vnodeops, &vp); 194 if (error) { 195 free(fd, M_TEMP); 196 return (error); 197 } 198 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 199 vp->v_data = fd; 200 fd->fd_vnode = vp; 201 fd->fd_type = ftype; 202 fd->fd_fd = fd_fd; 203 fd->fd_ix = ix; 204 error = insmntque1(vp, mp, fdesc_insmntque_dtr, NULL); 205 if (error != 0) { 206 *vpp = NULLVP; 207 return (error); 208 } 209 210 /* Make sure that someone didn't beat us when inserting the vnode. */ 211 mtx_lock(&fdesc_hashmtx); 212 /* 213 * If a forced unmount is progressing, we need to drop it. The flags are 214 * protected by the hashmtx. 215 */ 216 fmp = (struct fdescmount *)mp->mnt_data; 217 if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) { 218 mtx_unlock(&fdesc_hashmtx); 219 vgone(vp); 220 vput(vp); 221 *vpp = NULLVP; 222 return (-1); 223 } 224 225 LIST_FOREACH(fd2, fc, fd_hash) { 226 if (fd2->fd_ix == ix && fd2->fd_vnode->v_mount == mp) { 227 /* Get reference to vnode in case it's being free'd */ 228 vp2 = fd2->fd_vnode; 229 VI_LOCK(vp2); 230 mtx_unlock(&fdesc_hashmtx); 231 error = vget(vp2, LK_EXCLUSIVE | LK_INTERLOCK, td); 232 /* Someone beat us, dec use count and wait for reclaim */ 233 vgone(vp); 234 vput(vp); 235 /* If we didn't get it, return no vnode. */ 236 if (error) 237 vp2 = NULLVP; 238 *vpp = vp2; 239 return (error); 240 } 241 } 242 243 /* If we came here, we can insert it safely. */ 244 LIST_INSERT_HEAD(fc, fd, fd_hash); 245 mtx_unlock(&fdesc_hashmtx); 246 *vpp = vp; 247 return (0); 248 } 249 250 /* 251 * vp is the current namei directory 252 * ndp is the name to locate in that directory... 253 */ 254 static int 255 fdesc_lookup(ap) 256 struct vop_lookup_args /* { 257 struct vnode * a_dvp; 258 struct vnode ** a_vpp; 259 struct componentname * a_cnp; 260 } */ *ap; 261 { 262 struct vnode **vpp = ap->a_vpp; 263 struct vnode *dvp = ap->a_dvp; 264 struct componentname *cnp = ap->a_cnp; 265 char *pname = cnp->cn_nameptr; 266 struct thread *td = cnp->cn_thread; 267 struct file *fp; 268 int nlen = cnp->cn_namelen; 269 u_int fd, fd1; 270 int error; 271 struct vnode *fvp; 272 273 if ((cnp->cn_flags & ISLASTCN) && 274 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 275 error = EROFS; 276 goto bad; 277 } 278 279 if (cnp->cn_namelen == 1 && *pname == '.') { 280 *vpp = dvp; 281 VREF(dvp); 282 return (0); 283 } 284 285 if (VTOFDESC(dvp)->fd_type != Froot) { 286 error = ENOTDIR; 287 goto bad; 288 } 289 290 fd = 0; 291 /* the only time a leading 0 is acceptable is if it's "" */ 292 if (*pname == '' && nlen != 1) { 293 error = ENOENT; 294 goto bad; 295 } 296 while (nlen--) { 297 if (*pname < '' || *pname > '9') { 298 error = ENOENT; 299 goto bad; 300 } 301 fd1 = 10 * fd + *pname++ - ''; 302 if (fd1 < fd) { 303 error = ENOENT; 304 goto bad; 305 } 306 fd = fd1; 307 } 308 309 /* 310 * No rights to check since 'fp' isn't actually used. 311 */ 312 if ((error = fget(td, fd, 0, &fp)) != 0) 313 goto bad; 314 315 /* Check if we're looking up ourselves. */ 316 if (VTOFDESC(dvp)->fd_ix == FD_DESC + fd) { 317 /* 318 * In case we're holding the last reference to the file, the dvp 319 * will be re-acquired. 320 */ 321 vhold(dvp); 322 VOP_UNLOCK(dvp, 0); 323 fdrop(fp, td); 324 325 /* Re-aquire the lock afterwards. */ 326 vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE); 327 vdrop(dvp); 328 fvp = dvp; 329 } else { 330 /* 331 * Unlock our root node (dvp) when doing this, since we might 332 * deadlock since the vnode might be locked by another thread 333 * and the root vnode lock will be obtained afterwards (in case 334 * we're looking up the fd of the root vnode), which will be the 335 * opposite lock order. Vhold the root vnode first so we don't 336 * lose it. 337 */ 338 vhold(dvp); 339 VOP_UNLOCK(dvp, 0); 340 error = fdesc_allocvp(Fdesc, fd, FD_DESC + fd, dvp->v_mount, 341 &fvp); 342 fdrop(fp, td); 343 /* 344 * The root vnode must be locked last to prevent deadlock condition. 345 */ 346 vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE); 347 vdrop(dvp); 348 } 349 350 if (error) 351 goto bad; 352 *vpp = fvp; 353 return (0); 354 355 bad: 356 *vpp = NULL; 357 return (error); 358 } 359 360 static int 361 fdesc_open(ap) 362 struct vop_open_args /* { 363 struct vnode *a_vp; 364 int a_mode; 365 struct ucred *a_cred; 366 struct thread *a_td; 367 } */ *ap; 368 { 369 struct vnode *vp = ap->a_vp; 370 371 if (VTOFDESC(vp)->fd_type == Froot) 372 return (0); 373 374 /* 375 * XXX Kludge: set td->td_proc->p_dupfd to contain the value of the file 376 * descriptor being sought for duplication. The error return ensures 377 * that the vnode for this device will be released by vn_open. Open 378 * will detect this special error and take the actions in dupfdopen. 379 * Other callers of vn_open or VOP_OPEN will simply report the 380 * error. 381 */ 382 ap->a_td->td_dupfd = VTOFDESC(vp)->fd_fd; /* XXX */ 383 return (ENODEV); 384 } 385 386 static int 387 fdesc_getattr(ap) 388 struct vop_getattr_args /* { 389 struct vnode *a_vp; 390 struct vattr *a_vap; 391 struct ucred *a_cred; 392 } */ *ap; 393 { 394 struct vnode *vp = ap->a_vp; 395 struct vattr *vap = ap->a_vap; 396 397 vap->va_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH; 398 vap->va_fileid = VTOFDESC(vp)->fd_ix; 399 vap->va_uid = 0; 400 vap->va_gid = 0; 401 vap->va_blocksize = DEV_BSIZE; 402 vap->va_atime.tv_sec = boottime.tv_sec; 403 vap->va_atime.tv_nsec = 0; 404 vap->va_mtime = vap->va_atime; 405 vap->va_ctime = vap->va_mtime; 406 vap->va_gen = 0; 407 vap->va_flags = 0; 408 vap->va_bytes = 0; 409 vap->va_filerev = 0; 410 411 switch (VTOFDESC(vp)->fd_type) { 412 case Froot: 413 vap->va_type = VDIR; 414 vap->va_nlink = 2; 415 vap->va_size = DEV_BSIZE; 416 vap->va_rdev = NODEV; 417 break; 418 419 case Fdesc: 420 vap->va_type = VCHR; 421 vap->va_nlink = 1; 422 vap->va_size = 0; 423 vap->va_rdev = makedev(0, vap->va_fileid); 424 break; 425 426 default: 427 panic("fdesc_getattr"); 428 break; 429 } 430 431 vp->v_type = vap->va_type; 432 return (0); 433 } 434 435 static int 436 fdesc_setattr(ap) 437 struct vop_setattr_args /* { 438 struct vnode *a_vp; 439 struct vattr *a_vap; 440 struct ucred *a_cred; 441 } */ *ap; 442 { 443 struct vattr *vap = ap->a_vap; 444 struct vnode *vp; 445 struct mount *mp; 446 struct file *fp; 447 struct thread *td = curthread; 448 unsigned fd; 449 int error; 450 451 /* 452 * Can't mess with the root vnode 453 */ 454 if (VTOFDESC(ap->a_vp)->fd_type == Froot) 455 return (EACCES); 456 457 fd = VTOFDESC(ap->a_vp)->fd_fd; 458 459 /* 460 * Allow setattr where there is an underlying vnode. 461 */ 462 error = getvnode(td->td_proc->p_fd, fd, CAP_EXTATTR_SET, &fp); 463 if (error) { 464 /* 465 * getvnode() returns EINVAL if the file descriptor is not 466 * backed by a vnode. Silently drop all changes except 467 * chflags(2) in this case. 468 */ 469 if (error == EINVAL) { 470 if (vap->va_flags != VNOVAL) 471 error = EOPNOTSUPP; 472 else 473 error = 0; 474 } 475 return (error); 476 } 477 vp = fp->f_vnode; 478 if ((error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) == 0) { 479 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 480 error = VOP_SETATTR(vp, ap->a_vap, ap->a_cred); 481 VOP_UNLOCK(vp, 0); 482 vn_finished_write(mp); 483 } 484 fdrop(fp, td); 485 return (error); 486 } 487 488 #define UIO_MX 16 489 490 static int 491 fdesc_readdir(ap) 492 struct vop_readdir_args /* { 493 struct vnode *a_vp; 494 struct uio *a_uio; 495 struct ucred *a_cred; 496 int *a_eofflag; 497 u_long *a_cookies; 498 int a_ncookies; 499 } */ *ap; 500 { 501 struct uio *uio = ap->a_uio; 502 struct filedesc *fdp; 503 struct dirent d; 504 struct dirent *dp = &d; 505 int error, i, off, fcnt; 506 507 if (VTOFDESC(ap->a_vp)->fd_type != Froot) 508 panic("fdesc_readdir: not dir"); 509 510 if (ap->a_ncookies != NULL) 511 *ap->a_ncookies = 0; 512 513 off = (int)uio->uio_offset; 514 if (off != uio->uio_offset || off < 0 || (u_int)off % UIO_MX != 0 || 515 uio->uio_resid < UIO_MX) 516 return (EINVAL); 517 i = (u_int)off / UIO_MX; 518 fdp = uio->uio_td->td_proc->p_fd; 519 error = 0; 520 521 fcnt = i - 2; /* The first two nodes are `.' and `..' */ 522 523 FILEDESC_SLOCK(fdp); 524 while (i < fdp->fd_nfiles + 2 && uio->uio_resid >= UIO_MX) { 525 bzero((caddr_t)dp, UIO_MX); 526 switch (i) { 527 case 0: /* `.' */ 528 case 1: /* `..' */ 529 dp->d_fileno = i + FD_ROOT; 530 dp->d_namlen = i + 1; 531 dp->d_reclen = UIO_MX; 532 bcopy("..", dp->d_name, dp->d_namlen); 533 dp->d_name[i + 1] = '\0'; 534 dp->d_type = DT_DIR; 535 break; 536 default: 537 if (fdp->fd_ofiles[fcnt] == NULL) 538 break; 539 dp->d_namlen = sprintf(dp->d_name, "%d", fcnt); 540 dp->d_reclen = UIO_MX; 541 dp->d_type = DT_CHR; 542 dp->d_fileno = i + FD_DESC; 543 break; 544 } 545 if (dp->d_namlen != 0) { 546 /* 547 * And ship to userland 548 */ 549 FILEDESC_SUNLOCK(fdp); 550 error = uiomove(dp, UIO_MX, uio); 551 if (error) 552 goto done; 553 FILEDESC_SLOCK(fdp); 554 } 555 i++; 556 fcnt++; 557 } 558 FILEDESC_SUNLOCK(fdp); 559 560 done: 561 uio->uio_offset = i * UIO_MX; 562 return (error); 563 } 564 565 static int 566 fdesc_reclaim(ap) 567 struct vop_reclaim_args /* { 568 struct vnode *a_vp; 569 } */ *ap; 570 { 571 struct vnode *vp; 572 struct fdescnode *fd; 573 574 vp = ap->a_vp; 575 fd = VTOFDESC(vp); 576 fdesc_remove_entry(fd); 577 free(vp->v_data, M_TEMP); 578 vp->v_data = NULL; 579 return (0); 580 }
Cache object: 4876cf093b782f0a1b17f3ced1b7072b
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