1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
23 */
24
25 #include <sys/file.h>
26 #include <sys/stat.h>
27 #include <sys/atomic.h>
28 #include <sys/mntio.h>
29 #include <sys/mnttab.h>
30 #include <sys/mount.h>
31 #include <sys/sunddi.h>
32 #include <sys/sysmacros.h>
33 #include <sys/systm.h>
34 #include <sys/vfs.h>
35 #include <sys/vfs_opreg.h>
36 #include <sys/fs/mntdata.h>
37 #include <fs/fs_subr.h>
38 #include <sys/vmsystm.h>
39 #include <vm/seg_vn.h>
40 #include <sys/time.h>
41 #include <sys/ksynch.h>
42 #include <sys/sdt.h>
43
44 #define MNTROOTINO 2
45
46 static mntnode_t *mntgetnode(vnode_t *);
47
48 vnodeops_t *mntvnodeops;
49 extern void vfs_mnttab_readop(void);
50
51 /*
52 * Design of kernel mnttab accounting.
53 *
54 * mntfs provides two methods of reading the in-kernel mnttab, i.e. the state of
55 * the mounted resources: the read-only file /etc/mnttab, and a collection of
56 * ioctl() commands. Most of these interfaces are public and are described in
57 * mnttab(4). Three private ioctl() commands, MNTIOC_GETMNTENT,
58 * MNTIOC_GETEXTMNTENT and MNTIOC_GETMNTANY, provide for the getmntent(3C)
59 * family of functions, allowing them to support white space in mount names.
60 *
61 * A significant feature of mntfs is that it provides a file descriptor with a
62 * snapshot once it begins to consume mnttab data. Thus, as the process
63 * continues to consume data, its view of the in-kernel mnttab does not change
64 * even if resources are mounted or unmounted. The intent is to ensure that
65 * processes are guaranteed to read self-consistent data even as the system
66 * changes.
67 *
68 * The snapshot is implemented by a "database", unique to each zone, that
69 * comprises a linked list of mntelem_ts. The database is identified by
70 * zone_mntfs_db and is protected by zone_mntfs_db_lock. Each element contains
71 * the text entry in /etc/mnttab for a mounted resource, i.e. a vfs_t, and is
72 * marked with its time of "birth", i.e. creation. An element is "killed", and
73 * marked with its time of death, when it is found to be out of date, e.g. when
74 * the corresponding resource has been unmounted.
75 *
76 * When a process performs the first read() or ioctl() for a file descriptor for
77 * /etc/mnttab, the database is updated by a call to mntfs_snapshot() to ensure
78 * that an element exists for each currently mounted resource. Following this,
79 * the current time is written into a snapshot structure, a mntsnap_t, embedded
80 * in the descriptor's mntnode_t.
81 *
82 * mntfs is able to enumerate the /etc/mnttab entries corresponding to a
83 * particular file descriptor by searching the database for entries that were
84 * born before the appropriate snapshot and that either are still alive or died
85 * after the snapshot was created. Consumers use the iterator function
86 * mntfs_get_next_elem() to identify the next suitable element in the database.
87 *
88 * Each snapshot has a hold on its corresponding database elements, effected by
89 * a per-element reference count. At last close(), a snapshot is destroyed in
90 * mntfs_freesnap() by releasing all of its holds; an element is destroyed if
91 * its reference count becomes zero. Therefore the database never exists unless
92 * there is at least one active consumer of /etc/mnttab.
93 *
94 * getmntent(3C) et al. "do not open, close or rewind the file." This implies
95 * that getmntent() and read() must be able to operate without interaction on
96 * the same file descriptor; this is accomplished by the use of separate
97 * mntsnap_ts for both read() and ioctl().
98 *
99 * mntfs observes the following lock-ordering:
100 *
101 * mnp->mnt_contents -> vfslist -> zonep->zone_mntfs_db_lock
102 *
103 * NOTE: The following variable enables the generation of the "dev=xxx"
104 * in the option string for a mounted file system. Really this should
105 * be gotten rid of altogether, but for the sake of backwards compatibility
106 * we had to leave it in. It is defined as a 32-bit device number. This
107 * means that when 64-bit device numbers are in use, if either the major or
108 * minor part of the device number will not fit in a 16 bit quantity, the
109 * "dev=" will be set to NODEV (0x7fffffff). See PSARC 1999/566 and
110 * 1999/131 for details. The cmpldev() function used to generate the 32-bit
111 * device number handles this check and assigns the proper value.
112 */
113 int mntfs_enabledev = 1; /* enable old "dev=xxx" option */
114
115 extern void vfs_mono_time(timespec_t *);
116 enum { MNTFS_FIRST, MNTFS_SECOND, MNTFS_NEITHER };
117
118 /*
119 * Determine whether a field within a line from /etc/mnttab contains actual
120 * content or simply the marker string "-". This never applies to the time,
121 * therefore the delimiter must be a tab.
122 */
123 #define MNTFS_REAL_FIELD(x) (*(x) != '-' || *((x) + 1) != '\t')
124
125 static int
126 mntfs_devsize(struct vfs *vfsp)
127 {
128 dev32_t odev;
129
130 (void) cmpldev(&odev, vfsp->vfs_dev);
131 return (snprintf(NULL, 0, "dev=%x", odev));
132 }
133
134 static int
135 mntfs_devprint(struct vfs *vfsp, char *buf)
136 {
137 dev32_t odev;
138
139 (void) cmpldev(&odev, vfsp->vfs_dev);
140 return (snprintf(buf, MAX_MNTOPT_STR, "dev=%x", odev));
141 }
142
143 /* Identify which, if either, of two supplied timespec structs is newer. */
144 static int
145 mntfs_newest(timespec_t *a, timespec_t *b)
146 {
147 if (a->tv_sec == b->tv_sec &&
148 a->tv_nsec == b->tv_nsec) {
149 return (MNTFS_NEITHER);
150 } else if (b->tv_sec > a->tv_sec ||
151 (b->tv_sec == a->tv_sec &&
152 b->tv_nsec > a->tv_nsec)) {
153 return (MNTFS_SECOND);
154 } else {
155 return (MNTFS_FIRST);
156 }
157 }
158
159 static int
160 mntfs_optsize(struct vfs *vfsp)
161 {
162 int i, size = 0;
163 mntopt_t *mop;
164
165 for (i = 0; i < vfsp->vfs_mntopts.mo_count; i++) {
166 mop = &vfsp->vfs_mntopts.mo_list[i];
167 if (mop->mo_flags & MO_NODISPLAY)
168 continue;
169 if (mop->mo_flags & MO_SET) {
170 if (size)
171 size++; /* space for comma */
172 size += strlen(mop->mo_name);
173 /*
174 * count option value if there is one
175 */
176 if (mop->mo_arg != NULL) {
177 size += strlen(mop->mo_arg) + 1;
178 }
179 }
180 }
181 if (vfsp->vfs_zone != NULL && vfsp->vfs_zone != global_zone) {
182 /*
183 * Add space for "zone=<zone_name>" if required.
184 */
185 if (size)
186 size++; /* space for comma */
187 size += sizeof ("zone=") - 1;
188 size += strlen(vfsp->vfs_zone->zone_name);
189 }
190 if (mntfs_enabledev) {
191 if (size != 0)
192 size++; /* space for comma */
193 size += mntfs_devsize(vfsp);
194 }
195 if (size == 0)
196 size = strlen("-");
197 return (size);
198 }
199
200 static int
201 mntfs_optprint(struct vfs *vfsp, char *buf)
202 {
203 int i, optinbuf = 0;
204 mntopt_t *mop;
205 char *origbuf = buf;
206
207 for (i = 0; i < vfsp->vfs_mntopts.mo_count; i++) {
208 mop = &vfsp->vfs_mntopts.mo_list[i];
209 if (mop->mo_flags & MO_NODISPLAY)
210 continue;
211 if (mop->mo_flags & MO_SET) {
212 if (optinbuf)
213 *buf++ = ',';
214 else
215 optinbuf = 1;
216 buf += snprintf(buf, MAX_MNTOPT_STR,
217 "%s", mop->mo_name);
218 /*
219 * print option value if there is one
220 */
221 if (mop->mo_arg != NULL) {
222 buf += snprintf(buf, MAX_MNTOPT_STR, "=%s",
223 mop->mo_arg);
224 }
225 }
226 }
227 if (vfsp->vfs_zone != NULL && vfsp->vfs_zone != global_zone) {
228 if (optinbuf)
229 *buf++ = ',';
230 else
231 optinbuf = 1;
232 buf += snprintf(buf, MAX_MNTOPT_STR, "zone=%s",
233 vfsp->vfs_zone->zone_name);
234 }
235 if (mntfs_enabledev) {
236 if (optinbuf++)
237 *buf++ = ',';
238 buf += mntfs_devprint(vfsp, buf);
239 }
240 if (!optinbuf) {
241 buf += snprintf(buf, MAX_MNTOPT_STR, "-");
242 }
243 return (buf - origbuf);
244 }
245
246 void
247 mntfs_populate_text(vfs_t *vfsp, zone_t *zonep, mntelem_t *elemp)
248 {
249 struct extmnttab *tabp = &elemp->mnte_tab;
250 const char *resource, *mntpt;
251 char *cp = elemp->mnte_text;
252 mntpt = refstr_value(vfsp->vfs_mntpt);
253 resource = refstr_value(vfsp->vfs_resource);
254
255 tabp->mnt_special = 0;
256 if (resource != NULL && resource[0] != '\0') {
257 if (resource[0] != '/') {
258 cp += snprintf(cp, MAXPATHLEN, "%s\t", resource);
259 } else if (!ZONE_PATH_VISIBLE(resource, zonep)) {
260 /*
261 * Use the mount point as the resource.
262 */
263 cp += snprintf(cp, MAXPATHLEN, "%s\t",
264 ZONE_PATH_TRANSLATE(mntpt, zonep));
265 } else {
266 cp += snprintf(cp, MAXPATHLEN, "%s\t",
267 ZONE_PATH_TRANSLATE(resource, zonep));
268 }
269 } else {
270 cp += snprintf(cp, MAXPATHLEN, "-\t");
271 }
272
273 tabp->mnt_mountp = (char *)(cp - elemp->mnte_text);
274 if (mntpt != NULL && mntpt[0] != '\0') {
275 /*
276 * We know the mount point is visible from within the zone,
277 * otherwise it wouldn't be on the zone's vfs list.
278 */
279 cp += snprintf(cp, MAXPATHLEN, "%s\t",
280 ZONE_PATH_TRANSLATE(mntpt, zonep));
281 } else {
282 cp += snprintf(cp, MAXPATHLEN, "-\t");
283 }
284
285 tabp->mnt_fstype = (char *)(cp - elemp->mnte_text);
286 cp += snprintf(cp, MAXPATHLEN, "%s\t",
287 vfssw[vfsp->vfs_fstype].vsw_name);
288
289 tabp->mnt_mntopts = (char *)(cp - elemp->mnte_text);
290 cp += mntfs_optprint(vfsp, cp);
291 *cp++ = '\t';
292
293 tabp->mnt_time = (char *)(cp - elemp->mnte_text);
294 cp += snprintf(cp, MAX_MNTOPT_STR, "%ld", vfsp->vfs_mtime);
295 *cp++ = '\n'; /* over-write snprintf's trailing null-byte */
296
297 tabp->mnt_major = getmajor(vfsp->vfs_dev);
298 tabp->mnt_minor = getminor(vfsp->vfs_dev);
299
300 elemp->mnte_text_size = cp - elemp->mnte_text;
301 elemp->mnte_vfs_ctime = vfsp->vfs_hrctime;
302 elemp->mnte_hidden = vfsp->vfs_flag & VFS_NOMNTTAB;
303 }
304
305 /* Determine the length of the /etc/mnttab entry for this vfs_t. */
306 static size_t
307 mntfs_text_len(vfs_t *vfsp, zone_t *zone)
308 {
309 size_t size = 0;
310 const char *resource, *mntpt;
311 size_t mntsize;
312
313 mntpt = refstr_value(vfsp->vfs_mntpt);
314 if (mntpt != NULL && mntpt[0] != '\0') {
315 mntsize = strlen(ZONE_PATH_TRANSLATE(mntpt, zone)) + 1;
316 } else {
317 mntsize = 2; /* "-\t" */
318 }
319 size += mntsize;
320
321 resource = refstr_value(vfsp->vfs_resource);
322 if (resource != NULL && resource[0] != '\0') {
323 if (resource[0] != '/') {
324 size += strlen(resource) + 1;
325 } else if (!ZONE_PATH_VISIBLE(resource, zone)) {
326 /*
327 * Same as the zone's view of the mount point.
328 */
329 size += mntsize;
330 } else {
331 size += strlen(ZONE_PATH_TRANSLATE(resource, zone)) + 1;
332 }
333 } else {
334 size += 2; /* "-\t" */
335 }
336 size += strlen(vfssw[vfsp->vfs_fstype].vsw_name) + 1;
337 size += mntfs_optsize(vfsp);
338 size += snprintf(NULL, 0, "\t%ld\n", vfsp->vfs_mtime);
339 return (size);
340 }
341
342 /* Destroy the resources associated with a snapshot element. */
343 static void
344 mntfs_destroy_elem(mntelem_t *elemp)
345 {
346 kmem_free(elemp->mnte_text, elemp->mnte_text_size);
347 kmem_free(elemp, sizeof (mntelem_t));
348 }
349
350 /*
351 * Return 1 if the given snapshot is in the range of the given element; return
352 * 0 otherwise.
353 */
354 static int
355 mntfs_elem_in_range(mntsnap_t *snapp, mntelem_t *elemp)
356 {
357 timespec_t *stimep = &snapp->mnts_time;
358 timespec_t *btimep = &elemp->mnte_birth;
359 timespec_t *dtimep = &elemp->mnte_death;
360
361 /*
362 * If a snapshot is in range of an element then the snapshot must have
363 * been created after the birth of the element, and either the element
364 * is still alive or it died after the snapshot was created.
365 */
366 if (mntfs_newest(btimep, stimep) == MNTFS_SECOND &&
367 (MNTFS_ELEM_IS_ALIVE(elemp) ||
368 mntfs_newest(stimep, dtimep) == MNTFS_SECOND))
369 return (1);
370 else
371 return (0);
372 }
373
374 /*
375 * Return the next valid database element, after the one provided, for a given
376 * snapshot; return NULL if none exists. The caller must hold the zone's
377 * database lock as a reader before calling this function.
378 */
379 static mntelem_t *
380 mntfs_get_next_elem(mntsnap_t *snapp, mntelem_t *elemp)
381 {
382 int show_hidden = snapp->mnts_flags & MNTS_SHOWHIDDEN;
383
384 do {
385 elemp = elemp->mnte_next;
386 } while (elemp &&
387 (!mntfs_elem_in_range(snapp, elemp) ||
388 (!show_hidden && elemp->mnte_hidden)));
389 return (elemp);
390 }
391
392 /*
393 * This function frees the resources associated with a mntsnap_t. It walks
394 * through the database, decrementing the reference count of any element that
395 * satisfies the snapshot. If the reference count of an element becomes zero
396 * then it is removed from the database.
397 */
398 static void
399 mntfs_freesnap(mntnode_t *mnp, mntsnap_t *snapp)
400 {
401 zone_t *zonep = MTOD(mnp)->mnt_zone_ref.zref_zone;
402 krwlock_t *dblockp = &zonep->zone_mntfs_db_lock;
403 mntelem_t **elempp = &zonep->zone_mntfs_db;
404 mntelem_t *elemp;
405 int show_hidden = snapp->mnts_flags & MNTS_SHOWHIDDEN;
406 size_t number_decremented = 0;
407
408 ASSERT(RW_WRITE_HELD(&mnp->mnt_contents));
409
410 /* Ignore an uninitialised snapshot. */
411 if (snapp->mnts_nmnts == 0)
412 return;
413
414 /* Drop the holds on any matching database elements. */
415 rw_enter(dblockp, RW_WRITER);
416 while ((elemp = *elempp) != NULL) {
417 if (mntfs_elem_in_range(snapp, elemp) &&
418 (!elemp->mnte_hidden || show_hidden) &&
419 ++number_decremented && --elemp->mnte_refcnt == 0) {
420 if ((*elempp = elemp->mnte_next) != NULL)
421 (*elempp)->mnte_prev = elemp->mnte_prev;
422 mntfs_destroy_elem(elemp);
423 } else {
424 elempp = &elemp->mnte_next;
425 }
426 }
427 rw_exit(dblockp);
428 ASSERT(number_decremented == snapp->mnts_nmnts);
429
430 /* Clear the snapshot data. */
431 bzero(snapp, sizeof (mntsnap_t));
432 }
433
434 /* Insert the new database element newp after the existing element prevp. */
435 static void
436 mntfs_insert_after(mntelem_t *newp, mntelem_t *prevp)
437 {
438 newp->mnte_prev = prevp;
439 newp->mnte_next = prevp->mnte_next;
440 prevp->mnte_next = newp;
441 if (newp->mnte_next != NULL)
442 newp->mnte_next->mnte_prev = newp;
443 }
444
445 /* Create and return a copy of a given database element. */
446 static mntelem_t *
447 mntfs_copy(mntelem_t *origp)
448 {
449 mntelem_t *copyp;
450
451 copyp = kmem_zalloc(sizeof (mntelem_t), KM_SLEEP);
452 copyp->mnte_vfs_ctime = origp->mnte_vfs_ctime;
453 copyp->mnte_text_size = origp->mnte_text_size;
454 copyp->mnte_text = kmem_alloc(copyp->mnte_text_size, KM_SLEEP);
455 bcopy(origp->mnte_text, copyp->mnte_text, copyp->mnte_text_size);
456 copyp->mnte_tab = origp->mnte_tab;
457 copyp->mnte_hidden = origp->mnte_hidden;
458
459 return (copyp);
460 }
461
462 /*
463 * Compare two database elements and determine whether or not the vfs_t payload
464 * data of each are the same. Return 1 if so and 0 otherwise.
465 */
466 static int
467 mntfs_is_same_element(mntelem_t *a, mntelem_t *b)
468 {
469 if (a->mnte_hidden == b->mnte_hidden &&
470 a->mnte_text_size == b->mnte_text_size &&
471 bcmp(a->mnte_text, b->mnte_text, a->mnte_text_size) == 0 &&
472 bcmp(&a->mnte_tab, &b->mnte_tab, sizeof (struct extmnttab)) == 0)
473 return (1);
474 else
475 return (0);
476 }
477
478 /*
479 * mntfs_snapshot() updates the database, creating it if necessary, so that it
480 * accurately reflects the state of the in-kernel mnttab. It also increments
481 * the reference count on all database elements that correspond to currently-
482 * mounted resources. Finally, it initialises the appropriate snapshot
483 * structure.
484 *
485 * Each vfs_t is given a high-resolution time stamp, for the benefit of mntfs,
486 * when it is inserted into the in-kernel mnttab. This time stamp is copied into
487 * the corresponding database element when it is created, allowing the element
488 * and the vfs_t to be identified as a pair. It is possible that some file
489 * systems may make unadvertised changes to, for example, a resource's mount
490 * options. Therefore, in order to determine whether a database element is an
491 * up-to-date representation of a given vfs_t, it is compared with a temporary
492 * element generated for this purpose. Although less efficient, this is safer
493 * than implementing an mtime for a vfs_t.
494 *
495 * Some mounted resources are marked as "hidden" with a VFS_NOMNTTAB flag. These
496 * are considered invisible unless the user has already set the MNT_SHOWHIDDEN
497 * flag in the vnode using the MNTIOC_SHOWHIDDEN ioctl.
498 */
499 static void
500 mntfs_snapshot(mntnode_t *mnp, mntsnap_t *snapp)
501 {
502 mntdata_t *mnd = MTOD(mnp);
503 zone_t *zonep = mnd->mnt_zone_ref.zref_zone;
504 int is_global_zone = (zonep == global_zone);
505 int show_hidden = mnp->mnt_flags & MNT_SHOWHIDDEN;
506 vfs_t *vfsp, *firstvfsp, *lastvfsp;
507 vfs_t dummyvfs;
508 vfs_t *dummyvfsp = NULL;
509 krwlock_t *dblockp = &zonep->zone_mntfs_db_lock;
510 mntelem_t **headpp = &zonep->zone_mntfs_db;
511 mntelem_t *elemp;
512 mntelem_t *prevp = NULL;
513 int order;
514 mntelem_t *tempelemp;
515 mntelem_t *newp;
516 mntelem_t *firstp = NULL;
517 size_t nmnts = 0;
518 size_t total_text_size = 0;
519 size_t normal_text_size = 0;
520 int insert_before;
521 timespec_t last_mtime;
522 size_t entry_length, new_entry_length;
523
524
525 ASSERT(RW_WRITE_HELD(&mnp->mnt_contents));
526 vfs_list_read_lock();
527 vfs_mnttab_modtime(&last_mtime);
528
529 /*
530 * If this snapshot already exists then we must have been asked to
531 * rewind the file, i.e. discard the snapshot and create a new one in
532 * its place. In this case we first see if the in-kernel mnttab has
533 * advertised a change; if not then we simply reinitialise the metadata.
534 */
535 if (snapp->mnts_nmnts) {
536 if (mntfs_newest(&last_mtime, &snapp->mnts_last_mtime) ==
537 MNTFS_NEITHER) {
538 /*
539 * An unchanged mtime is no guarantee that the
540 * in-kernel mnttab is unchanged; for example, a
541 * concurrent remount may be between calls to
542 * vfs_setmntopt_nolock() and vfs_mnttab_modtimeupd().
543 * It follows that the database may have changed, and
544 * in particular that some elements in this snapshot
545 * may have been killed by another call to
546 * mntfs_snapshot(). It is therefore not merely
547 * unnecessary to update the snapshot's time but in
548 * fact dangerous; it needs to be left alone.
549 */
550 snapp->mnts_next = snapp->mnts_first;
551 snapp->mnts_flags &= ~MNTS_REWIND;
552 snapp->mnts_foffset = snapp->mnts_ieoffset = 0;
553 vfs_list_unlock();
554 return;
555 } else {
556 mntfs_freesnap(mnp, snapp);
557 }
558 }
559
560 /*
561 * Create a temporary database element. For each vfs_t, the temporary
562 * element will be populated with the corresponding text. If the vfs_t
563 * does not have a corresponding element within the database, or if
564 * there is such an element but it is stale, a copy of the temporary
565 * element is inserted into the database at the appropriate location.
566 */
567 tempelemp = kmem_alloc(sizeof (mntelem_t), KM_SLEEP);
568 entry_length = MNT_LINE_MAX;
569 tempelemp->mnte_text = kmem_alloc(entry_length, KM_SLEEP);
570
571 /* Find the first and last vfs_t for the given zone. */
572 if (is_global_zone) {
573 firstvfsp = rootvfs;
574 lastvfsp = firstvfsp->vfs_prev;
575 } else {
576 firstvfsp = zonep->zone_vfslist;
577 /*
578 * If there isn't already a vfs_t for root then we create a
579 * dummy which will be used as the head of the list (which will
580 * therefore no longer be circular).
581 */
582 if (firstvfsp == NULL ||
583 strcmp(refstr_value(firstvfsp->vfs_mntpt),
584 zonep->zone_rootpath) != 0) {
585 /*
586 * The zone's vfs_ts will have mount points relative to
587 * the zone's root path. The vfs_t for the zone's
588 * root file system would therefore have a mount point
589 * equal to the zone's root path. Since the zone's root
590 * path isn't a mount point, we copy the vfs_t of the
591 * zone's root vnode, and provide it with a fake mount
592 * and resource. However, if the zone's root is a
593 * zfs dataset, use the dataset name as the resource.
594 *
595 * Note that by cloning another vfs_t we also acquire
596 * its high-resolution ctime. This might appear to
597 * violate the requirement that the ctimes in the list
598 * of vfs_ts are unique and monotonically increasing;
599 * this is not the case. The dummy vfs_t appears in only
600 * a non-global zone's vfs_t list, where the cloned
601 * vfs_t would not ordinarily be visible; the ctimes are
602 * therefore unique. The zone's root path must be
603 * available before the zone boots, and so its root
604 * vnode's vfs_t's ctime must be lower than those of any
605 * resources subsequently mounted by the zone. The
606 * ctimes are therefore monotonically increasing.
607 */
608 dummyvfs = *zonep->zone_rootvp->v_vfsp;
609 dummyvfs.vfs_mntpt = refstr_alloc(zonep->zone_rootpath);
610 if (strcmp(vfssw[dummyvfs.vfs_fstype].vsw_name, "zfs")
611 != 0)
612 dummyvfs.vfs_resource = dummyvfs.vfs_mntpt;
613 dummyvfsp = &dummyvfs;
614 if (firstvfsp == NULL) {
615 lastvfsp = dummyvfsp;
616 } else {
617 lastvfsp = firstvfsp->vfs_zone_prev;
618 dummyvfsp->vfs_zone_next = firstvfsp;
619 }
620 firstvfsp = dummyvfsp;
621 } else {
622 lastvfsp = firstvfsp->vfs_zone_prev;
623 }
624 }
625
626 /*
627 * Now walk through all the vfs_ts for this zone. For each one, find the
628 * corresponding database element, creating it first if necessary, and
629 * increment its reference count.
630 */
631 rw_enter(dblockp, RW_WRITER);
632 elemp = zonep->zone_mntfs_db;
633 /* CSTYLED */
634 for (vfsp = firstvfsp;;
635 vfsp = is_global_zone ? vfsp->vfs_next : vfsp->vfs_zone_next) {
636 DTRACE_PROBE1(new__vfs, vfs_t *, vfsp);
637 /* Consider only visible entries. */
638 if ((vfsp->vfs_flag & VFS_NOMNTTAB) == 0 || show_hidden) {
639 /*
640 * Walk through the existing database looking for either
641 * an element that matches the current vfs_t, or for the
642 * correct place in which to insert a new element.
643 */
644 insert_before = 0;
645 for (; elemp; prevp = elemp, elemp = elemp->mnte_next) {
646 DTRACE_PROBE1(considering__elem, mntelem_t *,
647 elemp);
648
649 /* Compare the vfs_t with the element. */
650 order = mntfs_newest(&elemp->mnte_vfs_ctime,
651 &vfsp->vfs_hrctime);
652
653 /*
654 * If we encounter a database element newer than
655 * this vfs_t then we've stepped over a gap
656 * where the element for this vfs_t must be
657 * inserted.
658 */
659 if (order == MNTFS_FIRST) {
660 insert_before = 1;
661 break;
662 }
663
664 /* Dead elements no longer interest us. */
665 if (MNTFS_ELEM_IS_DEAD(elemp))
666 continue;
667
668 /*
669 * If the time stamps are the same then the
670 * element is potential match for the vfs_t,
671 * although it may later prove to be stale.
672 */
673 if (order == MNTFS_NEITHER)
674 break;
675
676 /*
677 * This element must be older than the vfs_t.
678 * It must, therefore, correspond to a vfs_t
679 * that has been unmounted. Since the element is
680 * still alive, we kill it if it is visible.
681 */
682 if (!elemp->mnte_hidden || show_hidden)
683 vfs_mono_time(&elemp->mnte_death);
684 }
685 DTRACE_PROBE2(possible__match, vfs_t *, vfsp,
686 mntelem_t *, elemp);
687
688 /* Create a new database element if required. */
689 new_entry_length = mntfs_text_len(vfsp, zonep);
690 if (new_entry_length > entry_length) {
691 kmem_free(tempelemp->mnte_text, entry_length);
692 tempelemp->mnte_text =
693 kmem_alloc(new_entry_length, KM_SLEEP);
694 entry_length = new_entry_length;
695 }
696 mntfs_populate_text(vfsp, zonep, tempelemp);
697 ASSERT(tempelemp->mnte_text_size == new_entry_length);
698 if (elemp == NULL) {
699 /*
700 * We ran off the end of the database. Insert a
701 * new element at the end.
702 */
703 newp = mntfs_copy(tempelemp);
704 vfs_mono_time(&newp->mnte_birth);
705 if (prevp) {
706 mntfs_insert_after(newp, prevp);
707 } else {
708 newp->mnte_next = NULL;
709 newp->mnte_prev = NULL;
710 ASSERT(*headpp == NULL);
711 *headpp = newp;
712 }
713 elemp = newp;
714 } else if (insert_before) {
715 /*
716 * Insert a new element before the current one.
717 */
718 newp = mntfs_copy(tempelemp);
719 vfs_mono_time(&newp->mnte_birth);
720 if (prevp) {
721 mntfs_insert_after(newp, prevp);
722 } else {
723 newp->mnte_next = elemp;
724 newp->mnte_prev = NULL;
725 elemp->mnte_prev = newp;
726 ASSERT(*headpp == elemp);
727 *headpp = newp;
728 }
729 elemp = newp;
730 } else if (!mntfs_is_same_element(elemp, tempelemp)) {
731 /*
732 * The element corresponds to the vfs_t, but the
733 * vfs_t has changed; it must have been
734 * remounted. Kill the old element and insert a
735 * new one after it.
736 */
737 vfs_mono_time(&elemp->mnte_death);
738 newp = mntfs_copy(tempelemp);
739 vfs_mono_time(&newp->mnte_birth);
740 mntfs_insert_after(newp, elemp);
741 elemp = newp;
742 }
743
744 /* We've found the corresponding element. Hold it. */
745 DTRACE_PROBE1(incrementing, mntelem_t *, elemp);
746 elemp->mnte_refcnt++;
747
748 /*
749 * Update the parameters used to initialise the
750 * snapshot.
751 */
752 nmnts++;
753 total_text_size += elemp->mnte_text_size;
754 if (!elemp->mnte_hidden)
755 normal_text_size += elemp->mnte_text_size;
756 if (!firstp)
757 firstp = elemp;
758
759 prevp = elemp;
760 elemp = elemp->mnte_next;
761 }
762
763 if (vfsp == lastvfsp)
764 break;
765 }
766
767 /*
768 * Any remaining visible database elements that are still alive must be
769 * killed now, because their corresponding vfs_ts must have been
770 * unmounted.
771 */
772 for (; elemp; elemp = elemp->mnte_next) {
773 if (MNTFS_ELEM_IS_ALIVE(elemp) &&
774 (!elemp->mnte_hidden || show_hidden))
775 vfs_mono_time(&elemp->mnte_death);
776 }
777
778 /* Initialise the snapshot. */
779 vfs_mono_time(&snapp->mnts_time);
780 snapp->mnts_last_mtime = last_mtime;
781 snapp->mnts_first = snapp->mnts_next = firstp;
782 snapp->mnts_flags = show_hidden ? MNTS_SHOWHIDDEN : 0;
783 snapp->mnts_nmnts = nmnts;
784 snapp->mnts_text_size = total_text_size;
785 snapp->mnts_foffset = snapp->mnts_ieoffset = 0;
786
787 /*
788 * Record /etc/mnttab's current size and mtime for possible future use
789 * by mntgetattr().
790 */
791 mnd->mnt_size = normal_text_size;
792 mnd->mnt_mtime = last_mtime;
793 if (show_hidden) {
794 mnd->mnt_hidden_size = total_text_size;
795 mnd->mnt_hidden_mtime = last_mtime;
796 }
797
798 /* Clean up. */
799 rw_exit(dblockp);
800 vfs_list_unlock();
801 if (dummyvfsp != NULL)
802 refstr_rele(dummyvfsp->vfs_mntpt);
803 kmem_free(tempelemp->mnte_text, entry_length);
804 kmem_free(tempelemp, sizeof (mntelem_t));
805 }
806
807 /*
808 * Public function to convert vfs_mntopts into a string.
809 * A buffer of sufficient size is allocated, which is returned via bufp,
810 * and whose length is returned via lenp.
811 */
812 void
813 mntfs_getmntopts(struct vfs *vfsp, char **bufp, size_t *lenp)
814 {
815 size_t len;
816 char *buf;
817
818 vfs_list_read_lock();
819
820 len = mntfs_optsize(vfsp) + 1;
821 buf = kmem_alloc(len, KM_NOSLEEP);
822 if (buf == NULL) {
823 *bufp = NULL;
824 vfs_list_unlock();
825 return;
826 }
827 buf[len - 1] = '\0';
828 (void) mntfs_optprint(vfsp, buf);
829 ASSERT(buf[len - 1] == '\0');
830
831 vfs_list_unlock();
832 *bufp = buf;
833 *lenp = len;
834 }
835
836 /* ARGSUSED */
837 static int
838 mntopen(vnode_t **vpp, int flag, cred_t *cr, caller_context_t *ct)
839 {
840 vnode_t *vp = *vpp;
841 mntnode_t *nmnp;
842
843 /*
844 * Not allowed to open for writing, return error.
845 */
846 if (flag & FWRITE)
847 return (EPERM);
848 /*
849 * Create a new mnt/vnode for each open, this will give us a handle to
850 * hang the snapshot on.
851 */
852 nmnp = mntgetnode(vp);
853
854 *vpp = MTOV(nmnp);
855 atomic_inc_32(&MTOD(nmnp)->mnt_nopen);
856 VN_RELE(vp);
857 return (0);
858 }
859
860 /* ARGSUSED */
861 static int
862 mntclose(vnode_t *vp, int flag, int count, offset_t offset, cred_t *cr,
863 caller_context_t *ct)
864 {
865 mntnode_t *mnp = VTOM(vp);
866
867 /* Clean up any locks or shares held by the current process */
868 cleanlocks(vp, ttoproc(curthread)->p_pid, 0);
869 cleanshares(vp, ttoproc(curthread)->p_pid);
870
871 if (count > 1)
872 return (0);
873 if (vp->v_count == 1) {
874 rw_enter(&mnp->mnt_contents, RW_WRITER);
875 mntfs_freesnap(mnp, &mnp->mnt_read);
876 mntfs_freesnap(mnp, &mnp->mnt_ioctl);
877 rw_exit(&mnp->mnt_contents);
878 atomic_dec_32(&MTOD(mnp)->mnt_nopen);
879 }
880 return (0);
881 }
882
883 /* ARGSUSED */
884 static int
885 mntread(vnode_t *vp, uio_t *uio, int ioflag, cred_t *cred, caller_context_t *ct)
886 {
887 mntnode_t *mnp = VTOM(vp);
888 zone_t *zonep = MTOD(mnp)->mnt_zone_ref.zref_zone;
889 mntsnap_t *snapp = &mnp->mnt_read;
890 off_t off = uio->uio_offset;
891 size_t len = uio->uio_resid;
892 char *bufferp;
893 size_t available, copylen;
894 size_t written = 0;
895 mntelem_t *elemp;
896 krwlock_t *dblockp = &zonep->zone_mntfs_db_lock;
897 int error = 0;
898 off_t ieoffset;
899
900 rw_enter(&mnp->mnt_contents, RW_WRITER);
901 if (snapp->mnts_nmnts == 0 || (off == (off_t)0))
902 mntfs_snapshot(mnp, snapp);
903
904 if ((size_t)(off + len) > snapp->mnts_text_size)
905 len = snapp->mnts_text_size - off;
906
907 if (off < 0 || len > snapp->mnts_text_size) {
908 rw_exit(&mnp->mnt_contents);
909 return (EFAULT);
910 }
911
912 if (len == 0) {
913 rw_exit(&mnp->mnt_contents);
914 return (0);
915 }
916
917 /*
918 * For the file offset provided, locate the corresponding database
919 * element and calculate the corresponding offset within its text. If
920 * the file offset is the same as that reached during the last read(2)
921 * then use the saved element and intra-element offset.
922 */
923 rw_enter(dblockp, RW_READER);
924 if (off == 0 || (off == snapp->mnts_foffset)) {
925 elemp = snapp->mnts_next;
926 ieoffset = snapp->mnts_ieoffset;
927 } else {
928 off_t total_off;
929 /*
930 * Find the element corresponding to the requested file offset
931 * by walking through the database and summing the text sizes
932 * of the individual elements. If the requested file offset is
933 * greater than that reached on the last visit then we can start
934 * at the last seen element; otherwise, we have to start at the
935 * beginning.
936 */
937 if (off > snapp->mnts_foffset) {
938 elemp = snapp->mnts_next;
939 total_off = snapp->mnts_foffset - snapp->mnts_ieoffset;
940 } else {
941 elemp = snapp->mnts_first;
942 total_off = 0;
943 }
944 while (off > total_off + elemp->mnte_text_size) {
945 total_off += elemp->mnte_text_size;
946 elemp = mntfs_get_next_elem(snapp, elemp);
947 ASSERT(elemp != NULL);
948 }
949 /* Calculate the intra-element offset. */
950 if (off > total_off)
951 ieoffset = off - total_off;
952 else
953 ieoffset = 0;
954 }
955
956 /*
957 * Create a buffer and populate it with the text from successive
958 * database elements until it is full.
959 */
960 bufferp = kmem_alloc(len, KM_SLEEP);
961 while (written < len) {
962 available = elemp->mnte_text_size - ieoffset;
963 copylen = MIN(len - written, available);
964 bcopy(elemp->mnte_text + ieoffset, bufferp + written, copylen);
965 written += copylen;
966 if (copylen == available) {
967 elemp = mntfs_get_next_elem(snapp, elemp);
968 ASSERT(elemp != NULL || written == len);
969 ieoffset = 0;
970 } else {
971 ieoffset += copylen;
972 }
973 }
974 rw_exit(dblockp);
975
976 /*
977 * Write the populated buffer, update the snapshot's state if
978 * successful and then advertise our read.
979 */
980 error = uiomove(bufferp, len, UIO_READ, uio);
981 if (error == 0) {
982 snapp->mnts_next = elemp;
983 snapp->mnts_foffset = off + len;
984 snapp->mnts_ieoffset = ieoffset;
985 }
986 vfs_mnttab_readop();
987 rw_exit(&mnp->mnt_contents);
988
989 /* Clean up. */
990 kmem_free(bufferp, len);
991 return (error);
992 }
993
994 static int
995 mntgetattr(vnode_t *vp, vattr_t *vap, int flags, cred_t *cr,
996 caller_context_t *ct)
997 {
998 int mask = vap->va_mask;
999 int error;
1000 mntnode_t *mnp = VTOM(vp);
1001 timespec_t mtime, old_mtime;
1002 size_t size, old_size;
1003 mntdata_t *mntdata = MTOD(VTOM(vp));
1004 mntsnap_t *rsnapp, *isnapp;
1005 extern timespec_t vfs_mnttab_ctime;
1006
1007
1008 /* AT_MODE, AT_UID and AT_GID are derived from the underlying file. */
1009 if (mask & AT_MODE|AT_UID|AT_GID) {
1010 if (error = VOP_GETATTR(mnp->mnt_mountvp, vap, flags, cr, ct))
1011 return (error);
1012 }
1013
1014 /*
1015 * There are some minor subtleties in the determination of
1016 * /etc/mnttab's size and mtime. We wish to avoid any condition in
1017 * which, in the vicinity of a change to the in-kernel mnttab, we
1018 * return an old value for one but a new value for the other. We cannot
1019 * simply hold vfslist for the entire calculation because we might need
1020 * to call mntfs_snapshot(), which calls vfs_list_read_lock().
1021 */
1022 if (mask & AT_SIZE|AT_NBLOCKS) {
1023 rw_enter(&mnp->mnt_contents, RW_WRITER);
1024
1025 vfs_list_read_lock();
1026 vfs_mnttab_modtime(&mtime);
1027 if (mnp->mnt_flags & MNT_SHOWHIDDEN) {
1028 old_mtime = mntdata->mnt_hidden_mtime;
1029 old_size = mntdata->mnt_hidden_size;
1030 } else {
1031 old_mtime = mntdata->mnt_mtime;
1032 old_size = mntdata->mnt_size;
1033 }
1034 vfs_list_unlock();
1035
1036 rsnapp = &mnp->mnt_read;
1037 isnapp = &mnp->mnt_ioctl;
1038 if (rsnapp->mnts_nmnts || isnapp->mnts_nmnts) {
1039 /*
1040 * The mntnode already has at least one snapshot from
1041 * which to take the size; the user will understand from
1042 * mnttab(4) that the current size of the in-kernel
1043 * mnttab is irrelevant.
1044 */
1045 size = rsnapp->mnts_nmnts ? rsnapp->mnts_text_size :
1046 isnapp->mnts_text_size;
1047 } else if (mntfs_newest(&mtime, &old_mtime) == MNTFS_NEITHER) {
1048 /*
1049 * There is no existing valid snapshot but the in-kernel
1050 * mnttab has not changed since the time that the last
1051 * one was generated. Use the old file size; note that
1052 * it is guaranteed to be consistent with mtime, which
1053 * may be returned to the user later.
1054 */
1055 size = old_size;
1056 } else {
1057 /*
1058 * There is no snapshot and the in-kernel mnttab has
1059 * changed since the last one was created. We generate a
1060 * new snapshot which we use for not only the size but
1061 * also the mtime, thereby ensuring that the two are
1062 * consistent.
1063 */
1064 mntfs_snapshot(mnp, rsnapp);
1065 size = rsnapp->mnts_text_size;
1066 mtime = rsnapp->mnts_last_mtime;
1067 mntfs_freesnap(mnp, rsnapp);
1068 }
1069
1070 rw_exit(&mnp->mnt_contents);
1071 } else if (mask & AT_ATIME|AT_MTIME) {
1072 vfs_list_read_lock();
1073 vfs_mnttab_modtime(&mtime);
1074 vfs_list_unlock();
1075 }
1076
1077 /* Always look like a regular file. */
1078 if (mask & AT_TYPE)
1079 vap->va_type = VREG;
1080 /* Mode should basically be read only. */
1081 if (mask & AT_MODE)
1082 vap->va_mode &= 07444;
1083 if (mask & AT_FSID)
1084 vap->va_fsid = vp->v_vfsp->vfs_dev;
1085 /* Nodeid is always ROOTINO. */
1086 if (mask & AT_NODEID)
1087 vap->va_nodeid = (ino64_t)MNTROOTINO;
1088 /*
1089 * Set nlink to the number of open vnodes for mnttab info
1090 * plus one for existing.
1091 */
1092 if (mask & AT_NLINK)
1093 vap->va_nlink = mntdata->mnt_nopen + 1;
1094 if (mask & AT_SIZE)
1095 vap->va_size = size;
1096 if (mask & AT_ATIME)
1097 vap->va_atime = mtime;
1098 if (mask & AT_MTIME)
1099 vap->va_mtime = mtime;
1100 if (mask & AT_CTIME)
1101 vap->va_ctime = vfs_mnttab_ctime;
1102 if (mask & AT_RDEV)
1103 vap->va_rdev = 0;
1104 if (mask & AT_BLKSIZE)
1105 vap->va_blksize = DEV_BSIZE;
1106 if (mask & AT_NBLOCKS)
1107 vap->va_nblocks = btod(size);
1108 if (mask & AT_SEQ)
1109 vap->va_seq = 0;
1110
1111 return (0);
1112 }
1113
1114 static int
1115 mntaccess(vnode_t *vp, int mode, int flags, cred_t *cr,
1116 caller_context_t *ct)
1117 {
1118 mntnode_t *mnp = VTOM(vp);
1119
1120 if (mode & (VWRITE|VEXEC))
1121 return (EROFS);
1122
1123 /*
1124 * Do access check on the underlying directory vnode.
1125 */
1126 return (VOP_ACCESS(mnp->mnt_mountvp, mode, flags, cr, ct));
1127 }
1128
1129
1130 /*
1131 * New /mntfs vnode required; allocate it and fill in most of the fields.
1132 */
1133 static mntnode_t *
1134 mntgetnode(vnode_t *dp)
1135 {
1136 mntnode_t *mnp;
1137 vnode_t *vp;
1138
1139 mnp = kmem_zalloc(sizeof (mntnode_t), KM_SLEEP);
1140 mnp->mnt_vnode = vn_alloc(KM_SLEEP);
1141 mnp->mnt_mountvp = VTOM(dp)->mnt_mountvp;
1142 rw_init(&mnp->mnt_contents, NULL, RW_DEFAULT, NULL);
1143 vp = MTOV(mnp);
1144 vp->v_flag = VNOCACHE|VNOMAP|VNOSWAP|VNOMOUNT;
1145 vn_setops(vp, mntvnodeops);
1146 vp->v_vfsp = dp->v_vfsp;
1147 vp->v_type = VREG;
1148 vp->v_data = (caddr_t)mnp;
1149
1150 return (mnp);
1151 }
1152
1153 /*
1154 * Free the storage obtained from mntgetnode().
1155 */
1156 static void
1157 mntfreenode(mntnode_t *mnp)
1158 {
1159 vnode_t *vp = MTOV(mnp);
1160
1161 rw_destroy(&mnp->mnt_contents);
1162 vn_invalid(vp);
1163 vn_free(vp);
1164 kmem_free(mnp, sizeof (*mnp));
1165 }
1166
1167
1168 /* ARGSUSED */
1169 static int
1170 mntfsync(vnode_t *vp, int syncflag, cred_t *cr, caller_context_t *ct)
1171 {
1172 return (0);
1173 }
1174
1175 /* ARGSUSED */
1176 static void
1177 mntinactive(vnode_t *vp, cred_t *cr, caller_context_t *ct)
1178 {
1179 mntnode_t *mnp = VTOM(vp);
1180
1181 mntfreenode(mnp);
1182 }
1183
1184 /*
1185 * lseek(2) is supported only to rewind the file by resetmnttab(3C). Rewinding
1186 * has a special meaning for /etc/mnttab: it forces mntfs to refresh the
1187 * snapshot at the next ioctl().
1188 *
1189 * mnttab(4) explains that "the snapshot...is taken any time a read(2) is
1190 * performed at offset 0". We therefore ignore the read snapshot here.
1191 */
1192 /* ARGSUSED */
1193 static int
1194 mntseek(vnode_t *vp, offset_t ooff, offset_t *noffp, caller_context_t *ct)
1195 {
1196 mntnode_t *mnp = VTOM(vp);
1197
1198 if (*noffp == 0) {
1199 rw_enter(&mnp->mnt_contents, RW_WRITER);
1200 mnp->mnt_ioctl.mnts_flags |= MNTS_REWIND;
1201 rw_exit(&mnp->mnt_contents);
1202 }
1203
1204 return (0);
1205 }
1206
1207 /*
1208 * Return the answer requested to poll().
1209 * POLLRDBAND will return when the mtime of the mnttab
1210 * information is newer than the latest one read for this open.
1211 */
1212 /* ARGSUSED */
1213 static int
1214 mntpoll(vnode_t *vp, short ev, int any, short *revp, pollhead_t **phpp,
1215 caller_context_t *ct)
1216 {
1217 mntnode_t *mnp = VTOM(vp);
1218 mntsnap_t *snapp;
1219
1220 rw_enter(&mnp->mnt_contents, RW_READER);
1221 if (mntfs_newest(&mnp->mnt_ioctl.mnts_last_mtime,
1222 &mnp->mnt_read.mnts_last_mtime) == MNTFS_FIRST)
1223 snapp = &mnp->mnt_ioctl;
1224 else
1225 snapp = &mnp->mnt_read;
1226
1227 *revp = 0;
1228 *phpp = (pollhead_t *)NULL;
1229 if (ev & POLLIN)
1230 *revp |= POLLIN;
1231
1232 if (ev & POLLRDNORM)
1233 *revp |= POLLRDNORM;
1234
1235 if (ev & POLLRDBAND) {
1236 vfs_mnttab_poll(&snapp->mnts_last_mtime, phpp);
1237 if (*phpp == (pollhead_t *)NULL)
1238 *revp |= POLLRDBAND;
1239 }
1240 rw_exit(&mnp->mnt_contents);
1241
1242 if (*revp || *phpp != NULL || any) {
1243 return (0);
1244 }
1245 /*
1246 * If someone is polling an unsupported poll events (e.g.
1247 * POLLOUT, POLLPRI, etc.), just return POLLERR revents.
1248 * That way we will ensure that we don't return a 0
1249 * revents with a NULL pollhead pointer.
1250 */
1251 *revp = POLLERR;
1252 return (0);
1253 }
1254
1255 /*
1256 * mntfs_same_word() returns 1 if two words are the same in the context of
1257 * MNTIOC_GETMNTANY and 0 otherwise.
1258 *
1259 * worda is a memory address that lies somewhere in the buffer bufa; it cannot
1260 * be NULL since this is used to indicate to getmntany(3C) that the user does
1261 * not wish to match a particular field. The text to which worda points is
1262 * supplied by the user; if it is not null-terminated then it cannot match.
1263 *
1264 * Buffer bufb contains a line from /etc/mnttab, in which the fields are
1265 * delimited by tab or new-line characters. offb is the offset of the second
1266 * word within this buffer.
1267 *
1268 * mntfs_same_word() returns 1 if the words are the same and 0 otherwise.
1269 */
1270 int
1271 mntfs_same_word(char *worda, char *bufa, size_t sizea, off_t offb, char *bufb,
1272 size_t sizeb)
1273 {
1274 char *wordb = bufb + offb;
1275 int bytes_remaining;
1276
1277 ASSERT(worda != NULL);
1278
1279 bytes_remaining = MIN(((bufa + sizea) - worda),
1280 ((bufb + sizeb) - wordb));
1281 while (bytes_remaining && *worda == *wordb) {
1282 worda++;
1283 wordb++;
1284 bytes_remaining--;
1285 }
1286 if (bytes_remaining &&
1287 *worda == '\0' && (*wordb == '\t' || *wordb == '\n'))
1288 return (1);
1289 else
1290 return (0);
1291 }
1292
1293 /*
1294 * mntfs_special_info_string() returns which, if either, of VBLK or VCHR
1295 * corresponds to a supplied path. If the path is a special device then the
1296 * function optionally sets the major and minor numbers.
1297 */
1298 vtype_t
1299 mntfs_special_info_string(char *path, uint_t *major, uint_t *minor, cred_t *cr)
1300 {
1301 vattr_t vattr;
1302 vnode_t *vp;
1303 vtype_t type;
1304 int error;
1305
1306 if (path == NULL || *path != '/' ||
1307 lookupnameat(path + 1, UIO_SYSSPACE, FOLLOW, NULLVPP, &vp, rootdir))
1308 return (0);
1309
1310 vattr.va_mask = AT_TYPE | AT_RDEV;
1311 error = VOP_GETATTR(vp, &vattr, ATTR_REAL, cr, NULL);
1312 VN_RELE(vp);
1313
1314 if (error == 0 && ((type = vattr.va_type) == VBLK || type == VCHR)) {
1315 if (major && minor) {
1316 *major = getmajor(vattr.va_rdev);
1317 *minor = getminor(vattr.va_rdev);
1318 }
1319 return (type);
1320 } else {
1321 return (0);
1322 }
1323 }
1324
1325 /*
1326 * mntfs_special_info_element() extracts the name of the mounted resource
1327 * for a given element and copies it into a null-terminated string, which it
1328 * then passes to mntfs_special_info_string().
1329 */
1330 vtype_t
1331 mntfs_special_info_element(mntelem_t *elemp, cred_t *cr)
1332 {
1333 char *newpath;
1334 vtype_t type;
1335
1336 newpath = kmem_alloc(elemp->mnte_text_size, KM_SLEEP);
1337 bcopy(elemp->mnte_text, newpath, (off_t)(elemp->mnte_tab.mnt_mountp));
1338 *(newpath + (off_t)elemp->mnte_tab.mnt_mountp - 1) = '\0';
1339 type = mntfs_special_info_string(newpath, NULL, NULL, cr);
1340 kmem_free(newpath, elemp->mnte_text_size);
1341
1342 return (type);
1343 }
1344
1345 /*
1346 * Convert an address that points to a byte within a user buffer into an
1347 * address that points to the corresponding offset within a kernel buffer. If
1348 * the user address is NULL then make no conversion. If the address does not
1349 * lie within the buffer then reset it to NULL.
1350 */
1351 char *
1352 mntfs_import_addr(char *uaddr, char *ubufp, char *kbufp, size_t bufsize)
1353 {
1354 if (uaddr < ubufp || uaddr >= ubufp + bufsize)
1355 return (NULL);
1356 else
1357 return (kbufp + (uaddr - ubufp));
1358 }
1359
1360 /*
1361 * These 32-bit versions are to support STRUCT_DECL(9F) etc. in
1362 * mntfs_copyout_element() and mntioctl().
1363 */
1364 #ifdef _SYSCALL32_IMPL
1365 typedef struct extmnttab32 {
1366 uint32_t mnt_special;
1367 uint32_t mnt_mountp;
1368 uint32_t mnt_fstype;
1369 uint32_t mnt_mntopts;
1370 uint32_t mnt_time;
1371 uint_t mnt_major;
1372 uint_t mnt_minor;
1373 } extmnttab32_t;
1374
1375 typedef struct mnttab32 {
1376 uint32_t mnt_special;
1377 uint32_t mnt_mountp;
1378 uint32_t mnt_fstype;
1379 uint32_t mnt_mntopts;
1380 uint32_t mnt_time;
1381 } mnttab32_t;
1382
1383 struct mntentbuf32 {
1384 uint32_t mbuf_emp;
1385 uint_t mbuf_bufsize;
1386 uint32_t mbuf_buf;
1387 };
1388 #endif
1389
1390 /*
1391 * mntfs_copyout_element() is common code for the MNTIOC_GETMNTENT,
1392 * MNTIOC_GETEXTMNTENT and MNTIOC_GETMNTANY ioctls. Having identifed the
1393 * database element desired by the user, this function copies out the text and
1394 * the pointers to the relevant userland addresses. It returns 0 on success
1395 * and non-zero otherwise.
1396 */
1397 int
1398 mntfs_copyout_elem(mntelem_t *elemp, struct extmnttab *uemp,
1399 char *ubufp, int cmd, int datamodel)
1400 {
1401 STRUCT_DECL(extmnttab, ktab);
1402 char *dbbufp = elemp->mnte_text;
1403 size_t dbbufsize = elemp->mnte_text_size;
1404 struct extmnttab *dbtabp = &elemp->mnte_tab;
1405 size_t ssize;
1406 char *kbufp;
1407 int error = 0;
1408
1409
1410 /*
1411 * We create a struct extmnttab within the kernel of the size
1412 * determined by the user's data model. We then populate its
1413 * fields by combining the start address of the text buffer
1414 * supplied by the user, ubufp, with the offsets stored for
1415 * this database element within dbtabp, a pointer to a struct
1416 * extmnttab.
1417 *
1418 * Note that if the corresponding field is "-" this signifies
1419 * no real content, and we set the address to NULL. This does
1420 * not apply to mnt_time.
1421 */
1422 STRUCT_INIT(ktab, datamodel);
1423 STRUCT_FSETP(ktab, mnt_special,
1424 MNTFS_REAL_FIELD(dbbufp) ? ubufp : NULL);
1425 STRUCT_FSETP(ktab, mnt_mountp,
1426 MNTFS_REAL_FIELD(dbbufp + (off_t)dbtabp->mnt_mountp) ?
1427 ubufp + (off_t)dbtabp->mnt_mountp : NULL);
1428 STRUCT_FSETP(ktab, mnt_fstype,
1429 MNTFS_REAL_FIELD(dbbufp + (off_t)dbtabp->mnt_fstype) ?
1430 ubufp + (off_t)dbtabp->mnt_fstype : NULL);
1431 STRUCT_FSETP(ktab, mnt_mntopts,
1432 MNTFS_REAL_FIELD(dbbufp + (off_t)dbtabp->mnt_mntopts) ?
1433 ubufp + (off_t)dbtabp->mnt_mntopts : NULL);
1434 STRUCT_FSETP(ktab, mnt_time,
1435 ubufp + (off_t)dbtabp->mnt_time);
1436 if (cmd == MNTIOC_GETEXTMNTENT) {
1437 STRUCT_FSETP(ktab, mnt_major, dbtabp->mnt_major);
1438 STRUCT_FSETP(ktab, mnt_minor, dbtabp->mnt_minor);
1439 ssize = SIZEOF_STRUCT(extmnttab, datamodel);
1440 } else {
1441 ssize = SIZEOF_STRUCT(mnttab, datamodel);
1442 }
1443 if (copyout(STRUCT_BUF(ktab), uemp, ssize))
1444 return (EFAULT);
1445
1446 /*
1447 * We create a text buffer in the kernel into which we copy the
1448 * /etc/mnttab entry for this element. We change the tab and
1449 * new-line delimiters to null bytes before copying out the
1450 * buffer.
1451 */
1452 kbufp = kmem_alloc(dbbufsize, KM_SLEEP);
1453 bcopy(elemp->mnte_text, kbufp, dbbufsize);
1454 *(kbufp + (off_t)dbtabp->mnt_mountp - 1) =
1455 *(kbufp + (off_t)dbtabp->mnt_fstype - 1) =
1456 *(kbufp + (off_t)dbtabp->mnt_mntopts - 1) =
1457 *(kbufp + (off_t)dbtabp->mnt_time - 1) =
1458 *(kbufp + dbbufsize - 1) = '\0';
1459 if (copyout(kbufp, ubufp, dbbufsize))
1460 error = EFAULT;
1461
1462 kmem_free(kbufp, dbbufsize);
1463 return (error);
1464 }
1465
1466 /* ARGSUSED */
1467 static int
1468 mntioctl(struct vnode *vp, int cmd, intptr_t arg, int flag, cred_t *cr,
1469 int *rvalp, caller_context_t *ct)
1470 {
1471 uint_t *up = (uint_t *)arg;
1472 mntnode_t *mnp = VTOM(vp);
1473 mntsnap_t *snapp = &mnp->mnt_ioctl;
1474 int error = 0;
1475 zone_t *zonep = MTOD(mnp)->mnt_zone_ref.zref_zone;
1476 krwlock_t *dblockp = &zonep->zone_mntfs_db_lock;
1477 model_t datamodel = flag & DATAMODEL_MASK;
1478
1479 switch (cmd) {
1480
1481 case MNTIOC_NMNTS: /* get no. of mounted resources */
1482 {
1483 rw_enter(&mnp->mnt_contents, RW_READER);
1484 if (snapp->mnts_nmnts == 0 ||
1485 (snapp->mnts_flags & MNTS_REWIND)) {
1486 if (!rw_tryupgrade(&mnp->mnt_contents)) {
1487 rw_exit(&mnp->mnt_contents);
1488 rw_enter(&mnp->mnt_contents, RW_WRITER);
1489 }
1490 if (snapp->mnts_nmnts == 0 ||
1491 (snapp->mnts_flags & MNTS_REWIND))
1492 mntfs_snapshot(mnp, snapp);
1493 }
1494 rw_exit(&mnp->mnt_contents);
1495
1496 if (suword32(up, snapp->mnts_nmnts) != 0)
1497 error = EFAULT;
1498 break;
1499 }
1500
1501 case MNTIOC_GETDEVLIST: /* get mounted device major/minor nos */
1502 {
1503 size_t len;
1504 uint_t *devlist;
1505 mntelem_t *elemp;
1506 int i = 0;
1507
1508 rw_enter(&mnp->mnt_contents, RW_READER);
1509 if (snapp->mnts_nmnts == 0 ||
1510 (snapp->mnts_flags & MNTS_REWIND)) {
1511 if (!rw_tryupgrade(&mnp->mnt_contents)) {
1512 rw_exit(&mnp->mnt_contents);
1513 rw_enter(&mnp->mnt_contents, RW_WRITER);
1514 }
1515 if (snapp->mnts_nmnts == 0 ||
1516 (snapp->mnts_flags & MNTS_REWIND))
1517 mntfs_snapshot(mnp, snapp);
1518 rw_downgrade(&mnp->mnt_contents);
1519 }
1520
1521 /* Create a local buffer to hold the device numbers. */
1522 len = 2 * snapp->mnts_nmnts * sizeof (uint_t);
1523 devlist = kmem_alloc(len, KM_SLEEP);
1524
1525 /*
1526 * Walk the database elements for this snapshot and add their
1527 * major and minor numbers.
1528 */
1529 rw_enter(dblockp, RW_READER);
1530 for (elemp = snapp->mnts_first; elemp;
1531 elemp = mntfs_get_next_elem(snapp, elemp)) {
1532 devlist[2 * i] = elemp->mnte_tab.mnt_major;
1533 devlist[2 * i + 1] = elemp->mnte_tab.mnt_minor;
1534 i++;
1535 }
1536 rw_exit(dblockp);
1537 ASSERT(i == snapp->mnts_nmnts);
1538 rw_exit(&mnp->mnt_contents);
1539
1540 error = xcopyout(devlist, up, len);
1541 kmem_free(devlist, len);
1542 break;
1543 }
1544
1545 case MNTIOC_SETTAG: /* set tag on mounted file system */
1546 case MNTIOC_CLRTAG: /* clear tag on mounted file system */
1547 {
1548 struct mnttagdesc *dp = (struct mnttagdesc *)arg;
1549 STRUCT_DECL(mnttagdesc, tagdesc);
1550 char *cptr;
1551 uint32_t major, minor;
1552 char tagbuf[MAX_MNTOPT_TAG];
1553 char *pbuf;
1554 size_t len;
1555 uint_t start = 0;
1556 mntdata_t *mntdata = MTOD(mnp);
1557 zone_t *zone = mntdata->mnt_zone_ref.zref_zone;
1558
1559 STRUCT_INIT(tagdesc, flag & DATAMODEL_MASK);
1560 if (copyin(dp, STRUCT_BUF(tagdesc), STRUCT_SIZE(tagdesc))) {
1561 error = EFAULT;
1562 break;
1563 }
1564 pbuf = kmem_alloc(MAXPATHLEN, KM_SLEEP);
1565 if (zone != global_zone) {
1566 (void) strcpy(pbuf, zone->zone_rootpath);
1567 /* truncate "/" and nul */
1568 start = zone->zone_rootpathlen - 2;
1569 ASSERT(pbuf[start] == '/');
1570 }
1571 cptr = STRUCT_FGETP(tagdesc, mtd_mntpt);
1572 error = copyinstr(cptr, pbuf + start, MAXPATHLEN - start, &len);
1573 if (error) {
1574 kmem_free(pbuf, MAXPATHLEN);
1575 break;
1576 }
1577 if (start != 0 && pbuf[start] != '/') {
1578 kmem_free(pbuf, MAXPATHLEN);
1579 error = EINVAL;
1580 break;
1581 }
1582 cptr = STRUCT_FGETP(tagdesc, mtd_tag);
1583 if ((error = copyinstr(cptr, tagbuf, MAX_MNTOPT_TAG, &len))) {
1584 kmem_free(pbuf, MAXPATHLEN);
1585 break;
1586 }
1587 major = STRUCT_FGET(tagdesc, mtd_major);
1588 minor = STRUCT_FGET(tagdesc, mtd_minor);
1589 if (cmd == MNTIOC_SETTAG)
1590 error = vfs_settag(major, minor, pbuf, tagbuf, cr);
1591 else
1592 error = vfs_clrtag(major, minor, pbuf, tagbuf, cr);
1593 kmem_free(pbuf, MAXPATHLEN);
1594 break;
1595 }
1596
1597 case MNTIOC_SHOWHIDDEN:
1598 {
1599 rw_enter(&mnp->mnt_contents, RW_WRITER);
1600 mnp->mnt_flags |= MNT_SHOWHIDDEN;
1601 rw_exit(&mnp->mnt_contents);
1602 break;
1603 }
1604
1605 case MNTIOC_GETMNTANY:
1606 {
1607 STRUCT_DECL(mntentbuf, embuf); /* Our copy of user's embuf */
1608 STRUCT_DECL(extmnttab, ktab); /* Out copy of user's emp */
1609 struct extmnttab *uemp; /* uaddr of user's emp */
1610 char *ubufp; /* uaddr of user's text buf */
1611 size_t ubufsize; /* size of the above */
1612 struct extmnttab preftab; /* our version of user's emp */
1613 char *prefbuf; /* our copy of user's text */
1614 mntelem_t *elemp; /* a database element */
1615 struct extmnttab *dbtabp; /* element's extmnttab */
1616 char *dbbufp; /* element's text buf */
1617 size_t dbbufsize; /* size of the above */
1618 vtype_t type; /* type, if any, of special */
1619
1620
1621 /*
1622 * embuf is a struct embuf within the kernel. We copy into it
1623 * the struct embuf supplied by the user.
1624 */
1625 STRUCT_INIT(embuf, datamodel);
1626 if (copyin((void *) arg, STRUCT_BUF(embuf),
1627 STRUCT_SIZE(embuf))) {
1628 error = EFAULT;
1629 break;
1630 }
1631 uemp = STRUCT_FGETP(embuf, mbuf_emp);
1632 ubufp = STRUCT_FGETP(embuf, mbuf_buf);
1633 ubufsize = STRUCT_FGET(embuf, mbuf_bufsize);
1634
1635 /*
1636 * Check that the text buffer offered by the user is the
1637 * agreed size.
1638 */
1639 if (ubufsize != MNT_LINE_MAX) {
1640 error = EINVAL;
1641 break;
1642 }
1643
1644 /* Copy the user-supplied entry into a local buffer. */
1645 prefbuf = kmem_alloc(MNT_LINE_MAX, KM_SLEEP);
1646 if (copyin(ubufp, prefbuf, MNT_LINE_MAX)) {
1647 kmem_free(prefbuf, MNT_LINE_MAX);
1648 error = EFAULT;
1649 break;
1650 }
1651
1652 /* Ensure that any string within it is null-terminated. */
1653 *(prefbuf + MNT_LINE_MAX - 1) = 0;
1654
1655 /* Copy in the user-supplied mpref */
1656 STRUCT_INIT(ktab, datamodel);
1657 if (copyin(uemp, STRUCT_BUF(ktab),
1658 SIZEOF_STRUCT(mnttab, datamodel))) {
1659 kmem_free(prefbuf, MNT_LINE_MAX);
1660 error = EFAULT;
1661 break;
1662 }
1663
1664 /*
1665 * Copy the members of the user's pref struct into a local
1666 * struct. The pointers need to be offset and verified to
1667 * ensure that they lie within the bounds of the buffer.
1668 */
1669 preftab.mnt_special = mntfs_import_addr(STRUCT_FGETP(ktab,
1670 mnt_special), ubufp, prefbuf, MNT_LINE_MAX);
1671 preftab.mnt_mountp = mntfs_import_addr(STRUCT_FGETP(ktab,
1672 mnt_mountp), ubufp, prefbuf, MNT_LINE_MAX);
1673 preftab.mnt_fstype = mntfs_import_addr(STRUCT_FGETP(ktab,
1674 mnt_fstype), ubufp, prefbuf, MNT_LINE_MAX);
1675 preftab.mnt_mntopts = mntfs_import_addr(STRUCT_FGETP(ktab,
1676 mnt_mntopts), ubufp, prefbuf, MNT_LINE_MAX);
1677 preftab.mnt_time = mntfs_import_addr(STRUCT_FGETP(ktab,
1678 mnt_time), ubufp, prefbuf, MNT_LINE_MAX);
1679
1680 /*
1681 * If the user specifies a mounted resource that is a special
1682 * device then we capture its mode and major and minor numbers;
1683 * cf. the block comment below.
1684 */
1685 type = mntfs_special_info_string(preftab.mnt_special,
1686 &preftab.mnt_major, &preftab.mnt_minor, cr);
1687
1688 rw_enter(&mnp->mnt_contents, RW_WRITER);
1689 if (snapp->mnts_nmnts == 0 ||
1690 (snapp->mnts_flags & MNTS_REWIND))
1691 mntfs_snapshot(mnp, snapp);
1692
1693 /*
1694 * This is the core functionality that implements getmntany().
1695 * We walk through the mntfs database until we find an element
1696 * matching the user's preferences that are contained in
1697 * preftab. Typically, this means checking that the text
1698 * matches. However, the mounted resource is special: if the
1699 * user is looking for a special device then we must find a
1700 * database element with the same major and minor numbers and
1701 * the same type, i.e. VBLK or VCHR. The type is not recorded
1702 * in the element because it cannot be inferred from the vfs_t.
1703 * We therefore check the type of suitable candidates via
1704 * mntfs_special_info_element(); since this calls into the
1705 * underlying file system we make sure to drop the database lock
1706 * first.
1707 */
1708 elemp = snapp->mnts_next;
1709 rw_enter(dblockp, RW_READER);
1710 for (;;) {
1711 for (; elemp; elemp = mntfs_get_next_elem(snapp,
1712 elemp)) {
1713 dbtabp = &elemp->mnte_tab;
1714 dbbufp = elemp->mnte_text;
1715 dbbufsize = elemp->mnte_text_size;
1716
1717 if (((type &&
1718 dbtabp->mnt_major == preftab.mnt_major &&
1719 dbtabp->mnt_minor == preftab.mnt_minor &&
1720 MNTFS_REAL_FIELD(dbbufp)) ||
1721 (!type && (!preftab.mnt_special ||
1722 mntfs_same_word(preftab.mnt_special,
1723 prefbuf, MNT_LINE_MAX, (off_t)0, dbbufp,
1724 dbbufsize)))) &&
1725
1726 (!preftab.mnt_mountp || mntfs_same_word(
1727 preftab.mnt_mountp, prefbuf, MNT_LINE_MAX,
1728 (off_t)dbtabp->mnt_mountp, dbbufp,
1729 dbbufsize)) &&
1730
1731 (!preftab.mnt_fstype || mntfs_same_word(
1732 preftab.mnt_fstype, prefbuf, MNT_LINE_MAX,
1733 (off_t)dbtabp->mnt_fstype, dbbufp,
1734 dbbufsize)) &&
1735
1736 (!preftab.mnt_mntopts || mntfs_same_word(
1737 preftab.mnt_mntopts, prefbuf, MNT_LINE_MAX,
1738 (off_t)dbtabp->mnt_mntopts, dbbufp,
1739 dbbufsize)) &&
1740
1741 (!preftab.mnt_time || mntfs_same_word(
1742 preftab.mnt_time, prefbuf, MNT_LINE_MAX,
1743 (off_t)dbtabp->mnt_time, dbbufp,
1744 dbbufsize)))
1745 break;
1746 }
1747 rw_exit(dblockp);
1748
1749 if (elemp == NULL || type == 0 ||
1750 type == mntfs_special_info_element(elemp, cr))
1751 break;
1752
1753 rw_enter(dblockp, RW_READER);
1754 elemp = mntfs_get_next_elem(snapp, elemp);
1755 }
1756
1757 kmem_free(prefbuf, MNT_LINE_MAX);
1758
1759 /* If we failed to find a match then return EOF. */
1760 if (elemp == NULL) {
1761 rw_exit(&mnp->mnt_contents);
1762 *rvalp = MNTFS_EOF;
1763 break;
1764 }
1765
1766 /*
1767 * Check that the text buffer offered by the user will be large
1768 * enough to accommodate the text for this entry.
1769 */
1770 if (elemp->mnte_text_size > MNT_LINE_MAX) {
1771 rw_exit(&mnp->mnt_contents);
1772 *rvalp = MNTFS_TOOLONG;
1773 break;
1774 }
1775
1776 /*
1777 * Populate the user's struct mnttab and text buffer using the
1778 * element's contents.
1779 */
1780 if (mntfs_copyout_elem(elemp, uemp, ubufp, cmd, datamodel)) {
1781 error = EFAULT;
1782 } else {
1783 rw_enter(dblockp, RW_READER);
1784 elemp = mntfs_get_next_elem(snapp, elemp);
1785 rw_exit(dblockp);
1786 snapp->mnts_next = elemp;
1787 }
1788 rw_exit(&mnp->mnt_contents);
1789 break;
1790 }
1791
1792 case MNTIOC_GETMNTENT:
1793 case MNTIOC_GETEXTMNTENT:
1794 {
1795 STRUCT_DECL(mntentbuf, embuf); /* Our copy of user's embuf */
1796 struct extmnttab *uemp; /* uaddr of user's emp */
1797 char *ubufp; /* uaddr of user's text buf */
1798 size_t ubufsize; /* size of the above */
1799 mntelem_t *elemp; /* a database element */
1800
1801
1802 rw_enter(&mnp->mnt_contents, RW_WRITER);
1803 if (snapp->mnts_nmnts == 0 ||
1804 (snapp->mnts_flags & MNTS_REWIND))
1805 mntfs_snapshot(mnp, snapp);
1806 if ((elemp = snapp->mnts_next) == NULL) {
1807 rw_exit(&mnp->mnt_contents);
1808 *rvalp = MNTFS_EOF;
1809 break;
1810 }
1811
1812 /*
1813 * embuf is a struct embuf within the kernel. We copy into it
1814 * the struct embuf supplied by the user.
1815 */
1816 STRUCT_INIT(embuf, datamodel);
1817 if (copyin((void *) arg, STRUCT_BUF(embuf),
1818 STRUCT_SIZE(embuf))) {
1819 rw_exit(&mnp->mnt_contents);
1820 error = EFAULT;
1821 break;
1822 }
1823 uemp = STRUCT_FGETP(embuf, mbuf_emp);
1824 ubufp = STRUCT_FGETP(embuf, mbuf_buf);
1825 ubufsize = STRUCT_FGET(embuf, mbuf_bufsize);
1826
1827 /*
1828 * Check that the text buffer offered by the user will be large
1829 * enough to accommodate the text for this entry.
1830 */
1831 if (elemp->mnte_text_size > ubufsize) {
1832 rw_exit(&mnp->mnt_contents);
1833 *rvalp = MNTFS_TOOLONG;
1834 break;
1835 }
1836
1837 /*
1838 * Populate the user's struct mnttab and text buffer using the
1839 * element's contents.
1840 */
1841 if (mntfs_copyout_elem(elemp, uemp, ubufp, cmd, datamodel)) {
1842 error = EFAULT;
1843 } else {
1844 rw_enter(dblockp, RW_READER);
1845 elemp = mntfs_get_next_elem(snapp, elemp);
1846 rw_exit(dblockp);
1847 snapp->mnts_next = elemp;
1848 }
1849 rw_exit(&mnp->mnt_contents);
1850 break;
1851 }
1852
1853 default:
1854 error = EINVAL;
1855 break;
1856 }
1857
1858 return (error);
1859 }
1860
1861 /*
1862 * mntfs provides a new vnode for each open(2). Two vnodes will represent the
1863 * same instance of /etc/mnttab if they share the same (zone-specific) vfs.
1864 */
1865 /* ARGSUSED */
1866 int
1867 mntcmp(vnode_t *vp1, vnode_t *vp2, caller_context_t *ct)
1868 {
1869 return (vp1 != NULL && vp2 != NULL && vp1->v_vfsp == vp2->v_vfsp);
1870 }
1871
1872 /*
1873 * /mntfs vnode operations vector
1874 */
1875 const fs_operation_def_t mnt_vnodeops_template[] = {
1876 VOPNAME_OPEN, { .vop_open = mntopen },
1877 VOPNAME_CLOSE, { .vop_close = mntclose },
1878 VOPNAME_READ, { .vop_read = mntread },
1879 VOPNAME_IOCTL, { .vop_ioctl = mntioctl },
1880 VOPNAME_GETATTR, { .vop_getattr = mntgetattr },
1881 VOPNAME_ACCESS, { .vop_access = mntaccess },
1882 VOPNAME_FSYNC, { .vop_fsync = mntfsync },
1883 VOPNAME_INACTIVE, { .vop_inactive = mntinactive },
1884 VOPNAME_SEEK, { .vop_seek = mntseek },
1885 VOPNAME_POLL, { .vop_poll = mntpoll },
1886 VOPNAME_CMP, { .vop_cmp = mntcmp },
1887 VOPNAME_DISPOSE, { .error = fs_error },
1888 VOPNAME_SHRLOCK, { .error = fs_error },
1889 NULL, NULL
1890 };