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: releng/8.0/sys/fs/fdescfs/fdesc_vnops.c 192013 2009-05-12 09:28:45Z kib $
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)
149 fdntype ftype;
150 unsigned fd_fd;
151 int ix;
152 struct mount *mp;
153 struct vnode **vpp;
154 {
155 struct fdescmount *fmp;
156 struct fdhashhead *fc;
157 struct fdescnode *fd, *fd2;
158 struct vnode *vp, *vp2;
159 struct thread *td;
160 int error = 0;
161
162 td = curthread;
163 fc = FD_NHASH(ix);
164 loop:
165 mtx_lock(&fdesc_hashmtx);
166 /*
167 * If a forced unmount is progressing, we need to drop it. The flags are
168 * protected by the hashmtx.
169 */
170 fmp = (struct fdescmount *)mp->mnt_data;
171 if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) {
172 mtx_unlock(&fdesc_hashmtx);
173 return (-1);
174 }
175
176 LIST_FOREACH(fd, fc, fd_hash) {
177 if (fd->fd_ix == ix && fd->fd_vnode->v_mount == mp) {
178 /* Get reference to vnode in case it's being free'd */
179 vp = fd->fd_vnode;
180 VI_LOCK(vp);
181 mtx_unlock(&fdesc_hashmtx);
182 if (vget(vp, LK_EXCLUSIVE | LK_INTERLOCK, td))
183 goto loop;
184 *vpp = vp;
185 return (0);
186 }
187 }
188 mtx_unlock(&fdesc_hashmtx);
189
190 fd = malloc(sizeof(struct fdescnode), M_TEMP, M_WAITOK);
191
192 error = getnewvnode("fdescfs", mp, &fdesc_vnodeops, &vp);
193 if (error) {
194 free(fd, M_TEMP);
195 return (error);
196 }
197 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
198 vp->v_data = fd;
199 fd->fd_vnode = vp;
200 fd->fd_type = ftype;
201 fd->fd_fd = fd_fd;
202 fd->fd_ix = ix;
203 error = insmntque1(vp, mp, fdesc_insmntque_dtr, NULL);
204 if (error != 0) {
205 *vpp = NULLVP;
206 return (error);
207 }
208
209 /* Make sure that someone didn't beat us when inserting the vnode. */
210 mtx_lock(&fdesc_hashmtx);
211 /*
212 * If a forced unmount is progressing, we need to drop it. The flags are
213 * protected by the hashmtx.
214 */
215 fmp = (struct fdescmount *)mp->mnt_data;
216 if (fmp == NULL || fmp->flags & FMNT_UNMOUNTF) {
217 mtx_unlock(&fdesc_hashmtx);
218 vgone(vp);
219 vput(vp);
220 *vpp = NULLVP;
221 return (-1);
222 }
223
224 LIST_FOREACH(fd2, fc, fd_hash) {
225 if (fd2->fd_ix == ix && fd2->fd_vnode->v_mount == mp) {
226 /* Get reference to vnode in case it's being free'd */
227 vp2 = fd2->fd_vnode;
228 VI_LOCK(vp2);
229 mtx_unlock(&fdesc_hashmtx);
230 error = vget(vp2, LK_EXCLUSIVE | LK_INTERLOCK, td);
231 /* Someone beat us, dec use count and wait for reclaim */
232 vgone(vp);
233 vput(vp);
234 /* If we didn't get it, return no vnode. */
235 if (error)
236 vp2 = NULLVP;
237 *vpp = vp2;
238 return (error);
239 }
240 }
241
242 /* If we came here, we can insert it safely. */
243 LIST_INSERT_HEAD(fc, fd, fd_hash);
244 mtx_unlock(&fdesc_hashmtx);
245 *vpp = vp;
246 return (0);
247 }
248
249 /*
250 * vp is the current namei directory
251 * ndp is the name to locate in that directory...
252 */
253 static int
254 fdesc_lookup(ap)
255 struct vop_lookup_args /* {
256 struct vnode * a_dvp;
257 struct vnode ** a_vpp;
258 struct componentname * a_cnp;
259 } */ *ap;
260 {
261 struct vnode **vpp = ap->a_vpp;
262 struct vnode *dvp = ap->a_dvp;
263 struct componentname *cnp = ap->a_cnp;
264 char *pname = cnp->cn_nameptr;
265 struct thread *td = cnp->cn_thread;
266 struct file *fp;
267 int nlen = cnp->cn_namelen;
268 u_int fd, fd1;
269 int error;
270 struct vnode *fvp;
271
272 if ((cnp->cn_flags & ISLASTCN) &&
273 (cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME)) {
274 error = EROFS;
275 goto bad;
276 }
277
278 if (cnp->cn_namelen == 1 && *pname == '.') {
279 *vpp = dvp;
280 VREF(dvp);
281 return (0);
282 }
283
284 if (VTOFDESC(dvp)->fd_type != Froot) {
285 error = ENOTDIR;
286 goto bad;
287 }
288
289 fd = 0;
290 /* the only time a leading 0 is acceptable is if it's "" */
291 if (*pname == '' && nlen != 1) {
292 error = ENOENT;
293 goto bad;
294 }
295 while (nlen--) {
296 if (*pname < '' || *pname > '9') {
297 error = ENOENT;
298 goto bad;
299 }
300 fd1 = 10 * fd + *pname++ - '';
301 if (fd1 < fd) {
302 error = ENOENT;
303 goto bad;
304 }
305 fd = fd1;
306 }
307
308 if ((error = fget(td, fd, &fp)) != 0)
309 goto bad;
310
311 /* Check if we're looking up ourselves. */
312 if (VTOFDESC(dvp)->fd_ix == FD_DESC + fd) {
313 /*
314 * In case we're holding the last reference to the file, the dvp
315 * will be re-acquired.
316 */
317 vhold(dvp);
318 VOP_UNLOCK(dvp, 0);
319 fdrop(fp, td);
320
321 /* Re-aquire the lock afterwards. */
322 vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE);
323 vdrop(dvp);
324 fvp = dvp;
325 } else {
326 /*
327 * Unlock our root node (dvp) when doing this, since we might
328 * deadlock since the vnode might be locked by another thread
329 * and the root vnode lock will be obtained afterwards (in case
330 * we're looking up the fd of the root vnode), which will be the
331 * opposite lock order. Vhold the root vnode first so we don't
332 * loose it.
333 */
334 vhold(dvp);
335 VOP_UNLOCK(dvp, 0);
336 error = fdesc_allocvp(Fdesc, fd, FD_DESC + fd, dvp->v_mount,
337 &fvp);
338 fdrop(fp, td);
339 /*
340 * The root vnode must be locked last to prevent deadlock condition.
341 */
342 vn_lock(dvp, LK_RETRY | LK_EXCLUSIVE);
343 vdrop(dvp);
344 }
345
346 if (error)
347 goto bad;
348 *vpp = fvp;
349 return (0);
350
351 bad:
352 *vpp = NULL;
353 return (error);
354 }
355
356 static int
357 fdesc_open(ap)
358 struct vop_open_args /* {
359 struct vnode *a_vp;
360 int a_mode;
361 struct ucred *a_cred;
362 struct thread *a_td;
363 } */ *ap;
364 {
365 struct vnode *vp = ap->a_vp;
366
367 if (VTOFDESC(vp)->fd_type == Froot)
368 return (0);
369
370 /*
371 * XXX Kludge: set td->td_proc->p_dupfd to contain the value of the the file
372 * descriptor being sought for duplication. The error return ensures
373 * that the vnode for this device will be released by vn_open. Open
374 * will detect this special error and take the actions in dupfdopen.
375 * Other callers of vn_open or VOP_OPEN will simply report the
376 * error.
377 */
378 ap->a_td->td_dupfd = VTOFDESC(vp)->fd_fd; /* XXX */
379 return (ENODEV);
380 }
381
382 static int
383 fdesc_getattr(ap)
384 struct vop_getattr_args /* {
385 struct vnode *a_vp;
386 struct vattr *a_vap;
387 struct ucred *a_cred;
388 } */ *ap;
389 {
390 struct vnode *vp = ap->a_vp;
391 struct vattr *vap = ap->a_vap;
392
393 vap->va_mode = S_IRUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH;
394 vap->va_fileid = VTOFDESC(vp)->fd_ix;
395 vap->va_uid = 0;
396 vap->va_gid = 0;
397 vap->va_blocksize = DEV_BSIZE;
398 vap->va_atime.tv_sec = boottime.tv_sec;
399 vap->va_atime.tv_nsec = 0;
400 vap->va_mtime = vap->va_atime;
401 vap->va_ctime = vap->va_mtime;
402 vap->va_gen = 0;
403 vap->va_flags = 0;
404 vap->va_bytes = 0;
405 vap->va_filerev = 0;
406
407 switch (VTOFDESC(vp)->fd_type) {
408 case Froot:
409 vap->va_type = VDIR;
410 vap->va_nlink = 2;
411 vap->va_size = DEV_BSIZE;
412 vap->va_rdev = NODEV;
413 break;
414
415 case Fdesc:
416 vap->va_type = VCHR;
417 vap->va_nlink = 1;
418 vap->va_size = 0;
419 vap->va_rdev = makedev(0, vap->va_fileid);
420 break;
421
422 default:
423 panic("fdesc_getattr");
424 break;
425 }
426
427 vp->v_type = vap->va_type;
428 return (0);
429 }
430
431 static int
432 fdesc_setattr(ap)
433 struct vop_setattr_args /* {
434 struct vnode *a_vp;
435 struct vattr *a_vap;
436 struct ucred *a_cred;
437 } */ *ap;
438 {
439 struct vattr *vap = ap->a_vap;
440 struct vnode *vp;
441 struct mount *mp;
442 struct file *fp;
443 struct thread *td = curthread;
444 unsigned fd;
445 int error;
446
447 /*
448 * Can't mess with the root vnode
449 */
450 if (VTOFDESC(ap->a_vp)->fd_type == Froot)
451 return (EACCES);
452
453 fd = VTOFDESC(ap->a_vp)->fd_fd;
454
455 /*
456 * Allow setattr where there is an underlying vnode.
457 */
458 error = getvnode(td->td_proc->p_fd, fd, &fp);
459 if (error) {
460 /*
461 * getvnode() returns EINVAL if the file descriptor is not
462 * backed by a vnode. Silently drop all changes except
463 * chflags(2) in this case.
464 */
465 if (error == EINVAL) {
466 if (vap->va_flags != VNOVAL)
467 error = EOPNOTSUPP;
468 else
469 error = 0;
470 }
471 return (error);
472 }
473 vp = fp->f_vnode;
474 if ((error = vn_start_write(vp, &mp, V_WAIT | PCATCH)) == 0) {
475 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
476 error = VOP_SETATTR(vp, ap->a_vap, ap->a_cred);
477 VOP_UNLOCK(vp, 0);
478 vn_finished_write(mp);
479 }
480 fdrop(fp, td);
481 return (error);
482 }
483
484 #define UIO_MX 16
485
486 static int
487 fdesc_readdir(ap)
488 struct vop_readdir_args /* {
489 struct vnode *a_vp;
490 struct uio *a_uio;
491 struct ucred *a_cred;
492 int *a_eofflag;
493 u_long *a_cookies;
494 int a_ncookies;
495 } */ *ap;
496 {
497 struct uio *uio = ap->a_uio;
498 struct filedesc *fdp;
499 struct dirent d;
500 struct dirent *dp = &d;
501 int error, i, off, fcnt;
502
503 /*
504 * We don't allow exporting fdesc mounts, and currently local
505 * requests do not need cookies.
506 */
507 if (ap->a_ncookies)
508 panic("fdesc_readdir: not hungry");
509
510 if (VTOFDESC(ap->a_vp)->fd_type != Froot)
511 panic("fdesc_readdir: not dir");
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 switch (i) {
526 case 0: /* `.' */
527 case 1: /* `..' */
528 bzero((caddr_t)dp, UIO_MX);
529
530 dp->d_fileno = i + FD_ROOT;
531 dp->d_namlen = i + 1;
532 dp->d_reclen = UIO_MX;
533 bcopy("..", dp->d_name, dp->d_namlen);
534 dp->d_name[i + 1] = '\0';
535 dp->d_type = DT_DIR;
536 break;
537 default:
538 if (fdp->fd_ofiles[fcnt] == NULL) {
539 FILEDESC_SUNLOCK(fdp);
540 goto done;
541 }
542
543 bzero((caddr_t) dp, UIO_MX);
544 dp->d_namlen = sprintf(dp->d_name, "%d", fcnt);
545 dp->d_reclen = UIO_MX;
546 dp->d_type = DT_UNKNOWN;
547 dp->d_fileno = i + FD_DESC;
548 break;
549 }
550 /*
551 * And ship to userland
552 */
553 FILEDESC_SUNLOCK(fdp);
554 error = uiomove(dp, UIO_MX, uio);
555 if (error)
556 goto done;
557 FILEDESC_SLOCK(fdp);
558 i++;
559 fcnt++;
560 }
561 FILEDESC_SUNLOCK(fdp);
562
563 done:
564 uio->uio_offset = i * UIO_MX;
565 return (error);
566 }
567
568 static int
569 fdesc_reclaim(ap)
570 struct vop_reclaim_args /* {
571 struct vnode *a_vp;
572 } */ *ap;
573 {
574 struct vnode *vp;
575 struct fdescnode *fd;
576
577 vp = ap->a_vp;
578 fd = VTOFDESC(vp);
579 fdesc_remove_entry(fd);
580 free(vp->v_data, M_TEMP);
581 vp->v_data = NULL;
582 return (0);
583 }
Cache object: 50d335724cc0f25212fa2da73d8bf89a
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