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/conf.h> 44 #include <sys/dirent.h> 45 #include <sys/filedesc.h> 46 #include <sys/kernel.h> /* boottime */ 47 #include <sys/lock.h> 48 #include <sys/mutex.h> 49 #include <sys/malloc.h> 50 #include <sys/file.h> /* Must come after sys/malloc.h */ 51 #include <sys/mount.h> 52 #include <sys/namei.h> 53 #include <sys/proc.h> 54 #include <sys/stat.h> 55 #include <sys/vnode.h> 56 57 #include <fs/fdescfs/fdesc.h> 58 59 #define NFDCACHE 4 60 #define FD_NHASH(ix) \ 61 (&fdhashtbl[(ix) & fdhash]) 62 static LIST_HEAD(fdhashhead, fdescnode) *fdhashtbl; 63 static u_long fdhash; 64 65 struct mtx fdesc_hashmtx; 66 67 static vop_getattr_t fdesc_getattr; 68 static vop_lookup_t fdesc_lookup; 69 static vop_open_t fdesc_open; 70 static vop_readdir_t fdesc_readdir; 71 static vop_reclaim_t fdesc_reclaim; 72 static vop_setattr_t fdesc_setattr; 73 74 static struct vop_vector fdesc_vnodeops = { 75 .vop_default = &default_vnodeops, 76 77 .vop_access = VOP_NULL, 78 .vop_getattr = fdesc_getattr, 79 .vop_lookup = fdesc_lookup, 80 .vop_open = fdesc_open, 81 .vop_pathconf = vop_stdpathconf, 82 .vop_readdir = fdesc_readdir, 83 .vop_reclaim = fdesc_reclaim, 84 .vop_setattr = fdesc_setattr, 85 }; 86 87 static void fdesc_insmntque_dtr(struct vnode *, void *); 88 static void fdesc_remove_entry(struct fdescnode *); 89 90 /* 91 * Initialise cache headers 92 */ 93 int 94 fdesc_init(vfsp) 95 struct vfsconf *vfsp; 96 { 97 98 mtx_init(&fdesc_hashmtx, "fdescfs_hash", NULL, MTX_DEF); 99 fdhashtbl = hashinit(NFDCACHE, M_CACHE, &fdhash); 100 return (0); 101 } 102 103 /* 104 * Uninit ready for unload. 105 */ 106 int 107 fdesc_uninit(vfsp) 108 struct vfsconf *vfsp; 109 { 110 111 hashdestroy(fdhashtbl, M_CACHE, fdhash); 112 mtx_destroy(&fdesc_hashmtx); 113 return (0); 114 } 115 116 /* 117 * If allocating vnode fails, call this. 118 */ 119 static void 120 fdesc_insmntque_dtr(struct vnode *vp, void *arg) 121 { 122 123 vgone(vp); 124 vput(vp); 125 } 126 127 /* 128 * Remove an entry from the hash if it exists. 129 */ 130 static void 131 fdesc_remove_entry(struct fdescnode *fd) 132 { 133 struct fdhashhead *fc; 134 struct fdescnode *fd2; 135 136 fc = FD_NHASH(fd->fd_ix); 137 mtx_lock(&fdesc_hashmtx); 138 LIST_FOREACH(fd2, fc, fd_hash) { 139 if (fd == fd2) { 140 LIST_REMOVE(fd, fd_hash); 141 break; 142 } 143 } 144 mtx_unlock(&fdesc_hashmtx); 145 } 146 147 int 148 fdesc_allocvp(ftype, fd_fd, ix, mp, vpp, td) 149 fdntype ftype; 150 unsigned fd_fd; 151 int ix; 152 struct mount *mp; 153 struct vnode **vpp; 154 struct thread *td; 155 { 156 struct fdescmount *fmp; 157 struct fdhashhead *fc; 158 struct fdescnode *fd, *fd2; 159 struct vnode *vp, *vp2; 160 int error = 0; 161 162 fc = FD_NHASH(ix); 163 loop: 164 mtx_lock(&fdesc_hashmtx); 165 /* 166 * If a forced unmount is progressing, we need to drop it. The flags are 167 * protected by the hashmtx. 168 */ 169 fmp = (struct fdescmount *)mp->mnt_data; 170 if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) { 171 mtx_unlock(&fdesc_hashmtx); 172 return (-1); 173 } 174 175 LIST_FOREACH(fd, fc, fd_hash) { 176 if (fd->fd_ix == ix && fd->fd_vnode->v_mount == mp) { 177 /* Get reference to vnode in case it's being free'd */ 178 vp = fd->fd_vnode; 179 VI_LOCK(vp); 180 mtx_unlock(&fdesc_hashmtx); 181 if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, td)) 182 goto loop; 183 *vpp = vp; 184 return (0); 185 } 186 } 187 mtx_unlock(&fdesc_hashmtx); 188 189 MALLOC(fd, struct fdescnode *, sizeof(struct fdescnode), M_TEMP, M_WAITOK); 190 191 error = getnewvnode("fdescfs", mp, &fdesc_vnodeops, &vp); 192 if (error) { 193 FREE(fd, M_TEMP); 194 return (error); 195 } 196 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 197 vp->v_data = fd; 198 fd->fd_vnode = vp; 199 fd->fd_type = ftype; 200 fd->fd_fd = fd_fd; 201 fd->fd_ix = ix; 202 error = insmntque1(vp, mp, fdesc_insmntque_dtr, NULL); 203 if (error != 0) { 204 *vpp = NULLVP; 205 return (error); 206 } 207 208 /* Make sure that someone didn't beat us when inserting the vnode. */ 209 mtx_lock(&fdesc_hashmtx); 210 /* 211 * If a forced unmount is progressing, we need to drop it. The flags are 212 * protected by the hashmtx. 213 */ 214 fmp = (struct fdescmount *)mp->mnt_data; 215 if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) { 216 mtx_unlock(&fdesc_hashmtx); 217 vgone(vp); 218 vput(vp); 219 *vpp = NULLVP; 220 return (-1); 221 } 222 223 LIST_FOREACH(fd2, fc, fd_hash) { 224 if (fd2->fd_ix == ix && fd2->fd_vnode->v_mount == mp) { 225 /* Get reference to vnode in case it's being free'd */ 226 vp2 = fd2->fd_vnode; 227 VI_LOCK(vp2); 228 mtx_unlock(&fdesc_hashmtx); 229 error = vget(vp2, LK_EXCLUSIVE | LK_INTERLOCK, td); 230 /* Someone beat us, dec use count and wait for reclaim */ 231 vgone(vp); 232 vput(vp); 233 /* If we didn't get it, return no vnode. */ 234 if (error) 235 vp2 = NULLVP; 236 *vpp = vp2; 237 return (error); 238 } 239 } 240 241 /* If we came here, we can insert it safely. */ 242 LIST_INSERT_HEAD(fc, fd, fd_hash); 243 mtx_unlock(&fdesc_hashmtx); 244 *vpp = vp; 245 return (0); 246 } 247 248 /* 249 * vp is the current namei directory 250 * ndp is the name to locate in that directory... 251 */ 252 static int 253 fdesc_lookup(ap) 254 struct vop_lookup_args /* { 255 struct vnode * a_dvp; 256 struct vnode ** a_vpp; 257 struct componentname * a_cnp; 258 } */ *ap; 259 { 260 struct vnode **vpp = ap->a_vpp; 261 struct vnode *dvp = ap->a_dvp; 262 struct componentname *cnp = ap->a_cnp; 263 char *pname = cnp->cn_nameptr; 264 struct thread *td = cnp->cn_thread; 265 struct file *fp; 266 int nlen = cnp->cn_namelen; 267 u_int fd, fd1; 268 int error; 269 struct vnode *fvp; 270 271 if ((cnp->cn_flags & ISLASTCN) && 272 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) { 273 error = EROFS; 274 goto bad; 275 } 276 277 if (cnp->cn_namelen == 1 && *pname == '.') { 278 *vpp = dvp; 279 VREF(dvp); 280 return (0); 281 } 282 283 if (VTOFDESC(dvp)->fd_type != Froot) { 284 error = ENOTDIR; 285 goto bad; 286 } 287 288 fd = 0; 289 /* the only time a leading 0 is acceptable is if it's "" */ 290 if (*pname == '' && nlen != 1) { 291 error = ENOENT; 292 goto bad; 293 } 294 while (nlen--) { 295 if (*pname < '' || *pname > '9') { 296 error = ENOENT; 297 goto bad; 298 } 299 fd1 = 10 * fd + *pname++ - ''; 300 if (fd1 < fd) { 301 error = ENOENT; 302 goto bad; 303 } 304 fd = fd1; 305 } 306 307 if ((error = fget(td, fd, &fp)) != 0) 308 goto bad; 309 310 /* Check if we're looking up ourselves. */ 311 if (VTOFDESC(dvp)->fd_ix == FD_DESC + fd) { 312 /* 313 * In case we're holding the last reference to the file, the dvp 314 * will be re-acquired. 315 */ 316 vhold(dvp); 317 VOP_UNLOCK(dvp, 0, td); 318 fdrop(fp, td); 319 320 /* Re-aquire the lock afterwards. */ 321 vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE, td); 322 vdrop(dvp); 323 fvp = dvp; 324 } else { 325 /* 326 * Unlock our root node (dvp) when doing this, since we might 327 * deadlock since the vnode might be locked by another thread 328 * and the root vnode lock will be obtained afterwards (in case 329 * we're looking up the fd of the root vnode), which will be the 330 * opposite lock order. Vhold the root vnode first so we don't 331 * loose it. 332 */ 333 vhold(dvp); 334 VOP_UNLOCK(dvp, 0, td); 335 error = fdesc_allocvp(Fdesc, fd, FD_DESC + fd, dvp->v_mount, 336 &fvp, td); 337 fdrop(fp, td); 338 /* 339 * The root vnode must be locked last to prevent deadlock condition. 340 */ 341 vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE, td); 342 vdrop(dvp); 343 } 344 345 if (error) 346 goto bad; 347 *vpp = fvp; 348 return (0); 349 350 bad: 351 *vpp = NULL; 352 return (error); 353 } 354 355 static int 356 fdesc_open(ap) 357 struct vop_open_args /* { 358 struct vnode *a_vp; 359 int a_mode; 360 struct ucred *a_cred; 361 struct thread *a_td; 362 } */ *ap; 363 { 364 struct vnode *vp = ap->a_vp; 365 366 if (VTOFDESC(vp)->fd_type == Froot) 367 return (0); 368 369 /* 370 * XXX Kludge: set td->td_proc->p_dupfd to contain the value of the file 371 * descriptor being sought for duplication. The error return ensures 372 * that the vnode for this device will be released by vn_open. Open 373 * will detect this special error and take the actions in dupfdopen. 374 * Other callers of vn_open or VOP_OPEN will simply report the 375 * error. 376 */ 377 ap->a_td->td_dupfd = VTOFDESC(vp)->fd_fd; /* XXX */ 378 return (ENODEV); 379 } 380 381 static int 382 fdesc_getattr(ap) 383 struct vop_getattr_args /* { 384 struct vnode *a_vp; 385 struct vattr *a_vap; 386 struct ucred *a_cred; 387 struct thread *a_td; 388 } */ *ap; 389 { 390 struct vnode *vp = ap->a_vp; 391 struct vattr *vap = ap->a_vap; 392 struct file *fp; 393 struct stat stb; 394 u_int fd; 395 int error = 0; 396 397 switch (VTOFDESC(vp)->fd_type) { 398 case Froot: 399 vap->va_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH; 400 vap->va_type = VDIR; 401 vap->va_nlink = 2; 402 vap->va_size = DEV_BSIZE; 403 vap->va_fileid = VTOFDESC(vp)->fd_ix; 404 vap->va_uid = 0; 405 vap->va_gid = 0; 406 vap->va_blocksize = DEV_BSIZE; 407 vap->va_atime.tv_sec = boottime.tv_sec; 408 vap->va_atime.tv_nsec = 0; 409 vap->va_mtime = vap->va_atime; 410 vap->va_ctime = vap->va_mtime; 411 vap->va_gen = 0; 412 vap->va_flags = 0; 413 vap->va_rdev = NODEV; 414 vap->va_bytes = 0; 415 vap->va_filerev = 0; 416 break; 417 418 case Fdesc: 419 fd = VTOFDESC(vp)->fd_fd; 420 421 if ((error = fget(ap->a_td, fd, &fp)) != 0) 422 return (error); 423 424 bzero(&stb, sizeof(stb)); 425 error = fo_stat(fp, &stb, ap->a_td->td_ucred, ap->a_td); 426 fdrop(fp, ap->a_td); 427 if (error == 0) { 428 vap->va_type = IFTOVT(stb.st_mode); 429 vap->va_mode = stb.st_mode; 430 #define FDRX (VREAD|VEXEC) 431 if (vap->va_type == VDIR) 432 vap->va_mode &= ~((FDRX)|(FDRX>>3)|(FDRX>>6)); 433 #undef FDRX 434 vap->va_nlink = 1; 435 vap->va_flags = 0; 436 vap->va_bytes = stb.st_blocks * stb.st_blksize; 437 vap->va_fileid = VTOFDESC(vp)->fd_ix; 438 vap->va_size = stb.st_size; 439 vap->va_blocksize = stb.st_blksize; 440 vap->va_rdev = stb.st_rdev; 441 442 /* 443 * If no time data is provided, use the current time. 444 */ 445 if (stb.st_atimespec.tv_sec == 0 && 446 stb.st_atimespec.tv_nsec == 0) 447 nanotime(&stb.st_atimespec); 448 449 if (stb.st_ctimespec.tv_sec == 0 && 450 stb.st_ctimespec.tv_nsec == 0) 451 nanotime(&stb.st_ctimespec); 452 453 if (stb.st_mtimespec.tv_sec == 0 && 454 stb.st_mtimespec.tv_nsec == 0) 455 nanotime(&stb.st_mtimespec); 456 457 vap->va_atime = stb.st_atimespec; 458 vap->va_mtime = stb.st_mtimespec; 459 vap->va_ctime = stb.st_ctimespec; 460 vap->va_uid = stb.st_uid; 461 vap->va_gid = stb.st_gid; 462 vap->va_gen = 0; 463 vap->va_filerev = 0; 464 } 465 break; 466 467 default: 468 panic("fdesc_getattr"); 469 break; 470 } 471 472 if (error == 0) 473 vp->v_type = vap->va_type; 474 return (error); 475 } 476 477 static int 478 fdesc_setattr(ap) 479 struct vop_setattr_args /* { 480 struct vnode *a_vp; 481 struct vattr *a_vap; 482 struct ucred *a_cred; 483 struct thread *a_td; 484 } */ *ap; 485 { 486 struct vattr *vap = ap->a_vap; 487 struct vnode *vp; 488 struct mount *mp; 489 struct file *fp; 490 unsigned fd; 491 int error; 492 493 /* 494 * Can't mess with the root vnode 495 */ 496 if (VTOFDESC(ap->a_vp)->fd_type == Froot) 497 return (EACCES); 498 499 fd = VTOFDESC(ap->a_vp)->fd_fd; 500 501 /* 502 * Allow setattr where there is an underlying vnode. 503 */ 504 error = getvnode(ap->a_td->td_proc->p_fd, fd, &fp); 505 if (error) { 506 /* 507 * getvnode() returns EINVAL if the file descriptor is not 508 * backed by a vnode. Silently drop all changes except 509 * chflags(2) in this case. 510 */ 511 if (error == EINVAL) { 512 if (vap->va_flags != VNOVAL) 513 error = EOPNOTSUPP; 514 else 515 error = 0; 516 } 517 return (error); 518 } 519 vp = fp->f_vnode; 520 if ((error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) == 0) { 521 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, ap->a_td); 522 error = VOP_SETATTR(vp, ap->a_vap, ap->a_cred, ap->a_td); 523 VOP_UNLOCK(vp, 0, ap->a_td); 524 vn_finished_write(mp); 525 } 526 fdrop(fp, ap->a_td); 527 return (error); 528 } 529 530 #define UIO_MX 16 531 532 static int 533 fdesc_readdir(ap) 534 struct vop_readdir_args /* { 535 struct vnode *a_vp; 536 struct uio *a_uio; 537 struct ucred *a_cred; 538 int *a_eofflag; 539 u_long *a_cookies; 540 int a_ncookies; 541 } */ *ap; 542 { 543 struct uio *uio = ap->a_uio; 544 struct filedesc *fdp; 545 struct dirent d; 546 struct dirent *dp = &d; 547 int error, i, off, fcnt; 548 549 /* 550 * We don't allow exporting fdesc mounts, and currently local 551 * requests do not need cookies. 552 */ 553 if (ap->a_ncookies) 554 panic("fdesc_readdir: not hungry"); 555 556 if (VTOFDESC(ap->a_vp)->fd_type != Froot) 557 panic("fdesc_readdir: not dir"); 558 559 off = (int)uio->uio_offset; 560 if (off != uio->uio_offset || off < 0 || (u_int)off % UIO_MX != 0 || 561 uio->uio_resid < UIO_MX) 562 return (EINVAL); 563 i = (u_int)off / UIO_MX; 564 fdp = uio->uio_td->td_proc->p_fd; 565 error = 0; 566 567 fcnt = i - 2; /* The first two nodes are `.' and `..' */ 568 569 FILEDESC_SLOCK(fdp); 570 while (i < fdp->fd_nfiles + 2 && uio->uio_resid >= UIO_MX) { 571 bzero((caddr_t)dp, UIO_MX); 572 switch (i) { 573 case 0: /* `.' */ 574 case 1: /* `..' */ 575 dp->d_fileno = i + FD_ROOT; 576 dp->d_namlen = i + 1; 577 dp->d_reclen = UIO_MX; 578 bcopy("..", dp->d_name, dp->d_namlen); 579 dp->d_name[i + 1] = '\0'; 580 dp->d_type = DT_DIR; 581 break; 582 default: 583 if (fdp->fd_ofiles[fcnt] == NULL) 584 break; 585 dp->d_namlen = sprintf(dp->d_name, "%d", fcnt); 586 dp->d_reclen = UIO_MX; 587 dp->d_type = DT_UNKNOWN; 588 dp->d_fileno = i + FD_DESC; 589 break; 590 } 591 if (dp->d_namlen != 0) { 592 /* 593 * And ship to userland 594 */ 595 FILEDESC_SUNLOCK(fdp); 596 error = uiomove(dp, UIO_MX, uio); 597 if (error) 598 goto done; 599 FILEDESC_SLOCK(fdp); 600 } 601 i++; 602 fcnt++; 603 } 604 FILEDESC_SUNLOCK(fdp); 605 606 done: 607 uio->uio_offset = i * UIO_MX; 608 return (error); 609 } 610 611 static int 612 fdesc_reclaim(ap) 613 struct vop_reclaim_args /* { 614 struct vnode *a_vp; 615 } */ *ap; 616 { 617 struct vnode *vp; 618 struct fdescnode *fd; 619 620 vp = ap->a_vp; 621 fd = VTOFDESC(vp); 622 fdesc_remove_entry(fd); 623 FREE(vp->v_data, M_TEMP); 624 vp->v_data = NULL; 625 return (0); 626 }
Cache object: 8c09f8e58bd56dbf802430fcae447328
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