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 2008 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 #pragma ident "%Z%%M% %I% %E% SMI"
27
28 /*
29 * The idea behind composition-based stacked filesystems is to add a
30 * vnode to the stack of vnodes for each mount. These vnodes have their
31 * own set of mount options and filesystem-specific functions, so they
32 * can modify data or operations before they are passed along. Such a
33 * filesystem must maintain a mapping from the underlying vnodes to its
34 * interposing vnodes.
35 *
36 * In lofs, this mapping is implemented by a hashtable. Each bucket
37 * contains a count of the number of nodes currently contained, the
38 * chain of vnodes, and a lock to protect the list of vnodes. The
39 * hashtable dynamically grows if the number of vnodes in the table as a
40 * whole exceeds the size of the table left-shifted by
41 * lo_resize_threshold. In order to minimize lock contention, there is
42 * no global lock protecting the hashtable, hence obtaining the
43 * per-bucket locks consists of a dance to make sure we've actually
44 * locked the correct bucket. Acquiring a bucket lock doesn't involve
45 * locking the hashtable itself, so we refrain from freeing old
46 * hashtables, and store them in a linked list of retired hashtables;
47 * the list is freed when the filesystem is unmounted.
48 */
49
50 #include <sys/param.h>
51 #include <sys/kmem.h>
52 #include <sys/vfs.h>
53 #include <sys/vnode.h>
54 #include <sys/cmn_err.h>
55 #include <sys/systm.h>
56 #include <sys/t_lock.h>
57 #include <sys/debug.h>
58 #include <sys/atomic.h>
59
60 #include <sys/fs/lofs_node.h>
61 #include <sys/fs/lofs_info.h>
62 /*
63 * Due to the hashing algorithm, the size of the hash table needs to be a
64 * power of 2.
65 */
66 #define LOFS_DEFAULT_HTSIZE (1 << 6)
67
68 #define ltablehash(vp, tblsz) ((((intptr_t)(vp))>>10) & ((tblsz)-1))
69
70 /*
71 * The following macros can only be safely used when the desired bucket
72 * is already locked.
73 */
74 /*
75 * The lock in the hashtable associated with the given vnode.
76 */
77 #define TABLE_LOCK(vp, li) \
78 (&(li)->li_hashtable[ltablehash((vp), (li)->li_htsize)].lh_lock)
79
80 /*
81 * The bucket in the hashtable that the given vnode hashes to.
82 */
83 #define TABLE_BUCKET(vp, li) \
84 ((li)->li_hashtable[ltablehash((vp), (li)->li_htsize)].lh_chain)
85
86 /*
87 * Number of elements currently in the bucket that the vnode hashes to.
88 */
89 #define TABLE_COUNT(vp, li) \
90 ((li)->li_hashtable[ltablehash((vp), (li)->li_htsize)].lh_count)
91
92 /*
93 * Grab/Drop the lock for the bucket this vnode hashes to.
94 */
95 #define TABLE_LOCK_ENTER(vp, li) table_lock_enter(vp, li)
96 #define TABLE_LOCK_EXIT(vp, li) \
97 mutex_exit(&(li)->li_hashtable[ltablehash((vp), \
98 (li)->li_htsize)].lh_lock)
99
100 static lnode_t *lfind(struct vnode *, struct loinfo *);
101 static void lsave(lnode_t *, struct loinfo *);
102 static struct vfs *makelfsnode(struct vfs *, struct loinfo *);
103 static struct lfsnode *lfsfind(struct vfs *, struct loinfo *);
104
105 uint_t lo_resize_threshold = 1;
106 uint_t lo_resize_factor = 2;
107
108 static kmem_cache_t *lnode_cache;
109
110 /*
111 * Since the hashtable itself isn't protected by a lock, obtaining a
112 * per-bucket lock proceeds as follows:
113 *
114 * (a) li->li_htlock protects li->li_hashtable, li->li_htsize, and
115 * li->li_retired.
116 *
117 * (b) Per-bucket locks (lh_lock) protect the contents of the bucket.
118 *
119 * (c) Locking order for resizing the hashtable is li_htlock then
120 * lh_lock.
121 *
122 * To grab the bucket lock we:
123 *
124 * (1) Stash away the htsize and the pointer to the hashtable to make
125 * sure neither change while we're using them.
126 *
127 * (2) lgrow() updates the pointer to the hashtable before it updates
128 * the size: the worst case scenario is that we have the wrong size (but
129 * the correct table), so we hash to the wrong bucket, grab the wrong
130 * lock, and then realize that things have changed, rewind and start
131 * again. If both the size and the table changed since we loaded them,
132 * we'll realize that too and restart.
133 *
134 * (3) The protocol for growing the hashtable involves holding *all* the
135 * locks in the table, hence the unlocking code (TABLE_LOCK_EXIT())
136 * doesn't need to do any dances, since neither the table nor the size
137 * can change while any bucket lock is held.
138 *
139 * (4) If the hashtable is growing (by thread t1) while another thread
140 * (t2) is trying to grab a bucket lock, t2 might have a stale reference
141 * to li->li_htsize:
142 *
143 * - t1 grabs all locks in lgrow()
144 * - t2 loads li->li_htsize and li->li_hashtable
145 * - t1 changes li->hashtable
146 * - t2 loads from an offset in the "stale" hashtable and tries to grab
147 * the relevant mutex.
148 *
149 * If t1 had free'd the stale hashtable, t2 would be in trouble. Hence,
150 * stale hashtables are not freed but stored in a list of "retired"
151 * hashtables, which is emptied when the filesystem is unmounted.
152 */
153 static void
table_lock_enter(vnode_t * vp,struct loinfo * li)154 table_lock_enter(vnode_t *vp, struct loinfo *li)
155 {
156 struct lobucket *chain;
157 uint_t htsize;
158 uint_t hash;
159
160 for (;;) {
161 htsize = li->li_htsize;
162 membar_consumer();
163 chain = (struct lobucket *)li->li_hashtable;
164 hash = ltablehash(vp, htsize);
165 mutex_enter(&chain[hash].lh_lock);
166 if (li->li_hashtable == chain && li->li_htsize == htsize)
167 break;
168 mutex_exit(&chain[hash].lh_lock);
169 }
170 }
171
172 void
lofs_subrinit(void)173 lofs_subrinit(void)
174 {
175 /*
176 * Initialize the cache.
177 */
178 lnode_cache = kmem_cache_create("lnode_cache", sizeof (lnode_t),
179 0, NULL, NULL, NULL, NULL, NULL, 0);
180 }
181
182 void
lofs_subrfini(void)183 lofs_subrfini(void)
184 {
185 kmem_cache_destroy(lnode_cache);
186 }
187
188 /*
189 * Initialize a (struct loinfo), and initialize the hashtable to have
190 * htsize buckets.
191 */
192 void
lsetup(struct loinfo * li,uint_t htsize)193 lsetup(struct loinfo *li, uint_t htsize)
194 {
195 li->li_refct = 0;
196 li->li_lfs = NULL;
197 if (htsize == 0)
198 htsize = LOFS_DEFAULT_HTSIZE;
199 li->li_htsize = htsize;
200 li->li_hashtable = kmem_zalloc(htsize * sizeof (*li->li_hashtable),
201 KM_SLEEP);
202 mutex_init(&li->li_lfslock, NULL, MUTEX_DEFAULT, NULL);
203 mutex_init(&li->li_htlock, NULL, MUTEX_DEFAULT, NULL);
204 li->li_retired = NULL;
205 }
206
207 /*
208 * Destroy a (struct loinfo)
209 */
210 void
ldestroy(struct loinfo * li)211 ldestroy(struct loinfo *li)
212 {
213 uint_t i, htsize;
214 struct lobucket *table;
215 struct lo_retired_ht *lrhp, *trhp;
216
217 mutex_destroy(&li->li_htlock);
218 mutex_destroy(&li->li_lfslock);
219 htsize = li->li_htsize;
220 table = li->li_hashtable;
221 for (i = 0; i < htsize; i++)
222 mutex_destroy(&table[i].lh_lock);
223 kmem_free(table, htsize * sizeof (*li->li_hashtable));
224
225 /*
226 * Free the retired hashtables.
227 */
228 lrhp = li->li_retired;
229 while (lrhp != NULL) {
230 trhp = lrhp;
231 lrhp = lrhp->lrh_next;
232 kmem_free(trhp->lrh_table,
233 trhp->lrh_size * sizeof (*li->li_hashtable));
234 kmem_free(trhp, sizeof (*trhp));
235 }
236 li->li_retired = NULL;
237 }
238
239 /*
240 * Return a looped back vnode for the given vnode.
241 * If no lnode exists for this vnode create one and put it
242 * in a table hashed by vnode. If the lnode for
243 * this vnode is already in the table return it (ref count is
244 * incremented by lfind). The lnode will be flushed from the
245 * table when lo_inactive calls freelonode. The creation of
246 * a new lnode can be forced via the LOF_FORCE flag even if
247 * the vnode exists in the table. This is used in the creation
248 * of a terminating lnode when looping is detected. A unique
249 * lnode is required for the correct evaluation of the current
250 * working directory.
251 * NOTE: vp is assumed to be a held vnode.
252 */
253 struct vnode *
makelonode(struct vnode * vp,struct loinfo * li,int flag)254 makelonode(struct vnode *vp, struct loinfo *li, int flag)
255 {
256 lnode_t *lp, *tlp;
257 struct vfs *vfsp;
258 vnode_t *nvp;
259
260 lp = NULL;
261 TABLE_LOCK_ENTER(vp, li);
262 if (flag != LOF_FORCE)
263 lp = lfind(vp, li);
264 if ((flag == LOF_FORCE) || (lp == NULL)) {
265 /*
266 * Optimistically assume that we won't need to sleep.
267 */
268 lp = kmem_cache_alloc(lnode_cache, KM_NOSLEEP);
269 nvp = vn_alloc(KM_NOSLEEP);
270 if (lp == NULL || nvp == NULL) {
271 TABLE_LOCK_EXIT(vp, li);
272 /* The lnode allocation may have succeeded, save it */
273 tlp = lp;
274 if (tlp == NULL) {
275 tlp = kmem_cache_alloc(lnode_cache, KM_SLEEP);
276 }
277 if (nvp == NULL) {
278 nvp = vn_alloc(KM_SLEEP);
279 }
280 lp = NULL;
281 TABLE_LOCK_ENTER(vp, li);
282 if (flag != LOF_FORCE)
283 lp = lfind(vp, li);
284 if (lp != NULL) {
285 kmem_cache_free(lnode_cache, tlp);
286 vn_free(nvp);
287 VN_RELE(vp);
288 goto found_lnode;
289 }
290 lp = tlp;
291 }
292 atomic_add_32(&li->li_refct, 1);
293 vfsp = makelfsnode(vp->v_vfsp, li);
294 lp->lo_vnode = nvp;
295 VN_SET_VFS_TYPE_DEV(nvp, vfsp, vp->v_type, vp->v_rdev);
296 nvp->v_flag |= (vp->v_flag & (VNOMOUNT|VNOMAP|VDIROPEN));
297 vn_setops(nvp, lo_vnodeops);
298 nvp->v_data = (caddr_t)lp;
299 lp->lo_vp = vp;
300 lp->lo_looping = 0;
301 lsave(lp, li);
302 vn_exists(vp);
303 } else {
304 VN_RELE(vp);
305 }
306
307 found_lnode:
308 TABLE_LOCK_EXIT(vp, li);
309 return (ltov(lp));
310 }
311
312 /*
313 * Get/Make vfs structure for given real vfs
314 */
315 static struct vfs *
makelfsnode(struct vfs * vfsp,struct loinfo * li)316 makelfsnode(struct vfs *vfsp, struct loinfo *li)
317 {
318 struct lfsnode *lfs;
319 struct lfsnode *tlfs;
320
321 /*
322 * Don't grab any locks for the fast (common) case.
323 */
324 if (vfsp == li->li_realvfs)
325 return (li->li_mountvfs);
326 ASSERT(li->li_refct > 0);
327 mutex_enter(&li->li_lfslock);
328 if ((lfs = lfsfind(vfsp, li)) == NULL) {
329 mutex_exit(&li->li_lfslock);
330 lfs = kmem_zalloc(sizeof (*lfs), KM_SLEEP);
331 mutex_enter(&li->li_lfslock);
332 if ((tlfs = lfsfind(vfsp, li)) != NULL) {
333 kmem_free(lfs, sizeof (*lfs));
334 lfs = tlfs;
335 goto found_lfs;
336 }
337 lfs->lfs_realvfs = vfsp;
338
339 /*
340 * Even though the lfsnode is strictly speaking a private
341 * implementation detail of lofs, it should behave as a regular
342 * vfs_t for the benefit of the rest of the kernel.
343 */
344 VFS_INIT(&lfs->lfs_vfs, lo_vfsops, (caddr_t)li);
345 lfs->lfs_vfs.vfs_fstype = li->li_mountvfs->vfs_fstype;
346 lfs->lfs_vfs.vfs_flag =
347 ((vfsp->vfs_flag | li->li_mflag) & ~li->li_dflag) &
348 INHERIT_VFS_FLAG;
349 lfs->lfs_vfs.vfs_bsize = vfsp->vfs_bsize;
350 lfs->lfs_vfs.vfs_dev = vfsp->vfs_dev;
351 lfs->lfs_vfs.vfs_fsid = vfsp->vfs_fsid;
352
353 if (vfsp->vfs_mntpt != NULL) {
354 lfs->lfs_vfs.vfs_mntpt = vfs_getmntpoint(vfsp);
355 /* Leave a reference to the mountpoint */
356 }
357
358 (void) VFS_ROOT(vfsp, &lfs->lfs_realrootvp);
359
360 /*
361 * We use 1 instead of 0 as the value to associate with
362 * an idle lfs_vfs. This is to prevent VFS_RELE()
363 * trying to kmem_free() our lfs_t (which is the wrong
364 * size).
365 */
366 VFS_HOLD(&lfs->lfs_vfs);
367 lfs->lfs_next = li->li_lfs;
368 li->li_lfs = lfs;
369 vfs_propagate_features(vfsp, &lfs->lfs_vfs);
370 }
371
372 found_lfs:
373 VFS_HOLD(&lfs->lfs_vfs);
374 mutex_exit(&li->li_lfslock);
375 return (&lfs->lfs_vfs);
376 }
377
378 /*
379 * Free lfs node since no longer in use
380 */
381 static void
freelfsnode(struct lfsnode * lfs,struct loinfo * li)382 freelfsnode(struct lfsnode *lfs, struct loinfo *li)
383 {
384 struct lfsnode *prev = NULL;
385 struct lfsnode *this;
386
387 ASSERT(MUTEX_HELD(&li->li_lfslock));
388 ASSERT(li->li_refct > 0);
389 for (this = li->li_lfs; this != NULL; this = this->lfs_next) {
390 if (this == lfs) {
391 ASSERT(lfs->lfs_vfs.vfs_count == 1);
392 if (prev == NULL)
393 li->li_lfs = lfs->lfs_next;
394 else
395 prev->lfs_next = lfs->lfs_next;
396 if (lfs->lfs_realrootvp != NULL) {
397 VN_RELE(lfs->lfs_realrootvp);
398 }
399 if (lfs->lfs_vfs.vfs_mntpt != NULL)
400 refstr_rele(lfs->lfs_vfs.vfs_mntpt);
401 if (lfs->lfs_vfs.vfs_implp != NULL) {
402 ASSERT(lfs->lfs_vfs.vfs_femhead == NULL);
403 ASSERT(lfs->lfs_vfs.vfs_vskap == NULL);
404 ASSERT(lfs->lfs_vfs.vfs_fstypevsp == NULL);
405 kmem_free(lfs->lfs_vfs.vfs_implp,
406 sizeof (vfs_impl_t));
407 }
408 sema_destroy(&lfs->lfs_vfs.vfs_reflock);
409 kmem_free(lfs, sizeof (struct lfsnode));
410 return;
411 }
412 prev = this;
413 }
414 panic("freelfsnode");
415 /*NOTREACHED*/
416 }
417
418 /*
419 * Find lfs given real vfs and mount instance(li)
420 */
421 static struct lfsnode *
lfsfind(struct vfs * vfsp,struct loinfo * li)422 lfsfind(struct vfs *vfsp, struct loinfo *li)
423 {
424 struct lfsnode *lfs;
425
426 ASSERT(MUTEX_HELD(&li->li_lfslock));
427
428 /*
429 * We need to handle the case where a UFS filesystem was forced
430 * unmounted and then a subsequent mount got the same vfs
431 * structure. If the new mount lies in the lofs hierarchy, then
432 * this will confuse lofs, because the original vfsp (of the
433 * forced unmounted filesystem) is still around. We check for
434 * this condition here.
435 *
436 * If we find a cache vfsp hit, then we check to see if the
437 * cached filesystem was forced unmounted. Skip all such
438 * entries. This should be safe to do since no
439 * makelonode()->makelfsnode()->lfsfind() calls should be
440 * generated for such force-unmounted filesystems (because (ufs)
441 * lookup would've returned an error).
442 */
443 for (lfs = li->li_lfs; lfs != NULL; lfs = lfs->lfs_next) {
444 if (lfs->lfs_realvfs == vfsp) {
445 struct vnode *realvp;
446
447 realvp = lfs->lfs_realrootvp;
448 if (realvp == NULL)
449 continue;
450 if (realvp->v_vfsp == NULL || realvp->v_type == VBAD)
451 continue;
452 return (lfs);
453 }
454 }
455 return (NULL);
456 }
457
458 /*
459 * Find real vfs given loopback vfs
460 */
461 struct vfs *
lo_realvfs(struct vfs * vfsp,struct vnode ** realrootvpp)462 lo_realvfs(struct vfs *vfsp, struct vnode **realrootvpp)
463 {
464 struct loinfo *li = vtoli(vfsp);
465 struct lfsnode *lfs;
466
467 ASSERT(li->li_refct > 0);
468 if (vfsp == li->li_mountvfs) {
469 if (realrootvpp != NULL)
470 *realrootvpp = vtol(li->li_rootvp)->lo_vp;
471 return (li->li_realvfs);
472 }
473 mutex_enter(&li->li_lfslock);
474 for (lfs = li->li_lfs; lfs != NULL; lfs = lfs->lfs_next) {
475 if (vfsp == &lfs->lfs_vfs) {
476 if (realrootvpp != NULL)
477 *realrootvpp = lfs->lfs_realrootvp;
478 mutex_exit(&li->li_lfslock);
479 return (lfs->lfs_realvfs);
480 }
481 }
482 panic("lo_realvfs");
483 /*NOTREACHED*/
484 }
485
486 /*
487 * Lnode lookup stuff.
488 * These routines maintain a table of lnodes hashed by vp so
489 * that the lnode for a vp can be found if it already exists.
490 *
491 * NB: A lofs shadow vnode causes exactly one VN_HOLD() on the
492 * underlying vnode.
493 */
494
495 /*
496 * Retire old hashtables.
497 */
498 static void
lretire(struct loinfo * li,struct lobucket * table,uint_t size)499 lretire(struct loinfo *li, struct lobucket *table, uint_t size)
500 {
501 struct lo_retired_ht *lrhp;
502
503 lrhp = kmem_alloc(sizeof (*lrhp), KM_SLEEP);
504 lrhp->lrh_table = table;
505 lrhp->lrh_size = size;
506
507 mutex_enter(&li->li_htlock);
508 lrhp->lrh_next = li->li_retired;
509 li->li_retired = lrhp;
510 mutex_exit(&li->li_htlock);
511 }
512
513 /*
514 * Grow the hashtable.
515 */
516 static void
lgrow(struct loinfo * li,uint_t newsize)517 lgrow(struct loinfo *li, uint_t newsize)
518 {
519 uint_t oldsize;
520 uint_t i;
521 struct lobucket *oldtable, *newtable;
522
523 /*
524 * It's OK to not have enough memory to resize the hashtable.
525 * We'll go down this path the next time we add something to the
526 * table, and retry the allocation then.
527 */
528 if ((newtable = kmem_zalloc(newsize * sizeof (*li->li_hashtable),
529 KM_NOSLEEP)) == NULL)
530 return;
531
532 mutex_enter(&li->li_htlock);
533 if (newsize <= li->li_htsize) {
534 mutex_exit(&li->li_htlock);
535 kmem_free(newtable, newsize * sizeof (*li->li_hashtable));
536 return;
537 }
538 oldsize = li->li_htsize;
539 oldtable = li->li_hashtable;
540
541 /*
542 * Grab all locks so TABLE_LOCK_ENTER() calls block until the
543 * resize is complete.
544 */
545 for (i = 0; i < oldsize; i++)
546 mutex_enter(&oldtable[i].lh_lock);
547 /*
548 * li->li_hashtable gets set before li->li_htsize, so in the
549 * time between the two assignments, callers of
550 * TABLE_LOCK_ENTER() cannot hash to a bucket beyond oldsize,
551 * hence we only need to grab the locks up to oldsize.
552 */
553 for (i = 0; i < oldsize; i++)
554 mutex_enter(&newtable[i].lh_lock);
555 /*
556 * Rehash.
557 */
558 for (i = 0; i < oldsize; i++) {
559 lnode_t *tlp, *nlp;
560
561 for (tlp = oldtable[i].lh_chain; tlp != NULL; tlp = nlp) {
562 uint_t hash = ltablehash(tlp->lo_vp, newsize);
563
564 nlp = tlp->lo_next;
565 tlp->lo_next = newtable[hash].lh_chain;
566 newtable[hash].lh_chain = tlp;
567 newtable[hash].lh_count++;
568 }
569 }
570
571 /*
572 * As soon as we store the new hashtable, future locking operations
573 * will use it. Therefore, we must ensure that all the state we've
574 * just established reaches global visibility before the new hashtable
575 * does.
576 */
577 membar_producer();
578 li->li_hashtable = newtable;
579
580 /*
581 * table_lock_enter() relies on the fact that li->li_hashtable
582 * is set to its new value before li->li_htsize.
583 */
584 membar_producer();
585 li->li_htsize = newsize;
586
587 /*
588 * The new state is consistent now, so we can drop all the locks.
589 */
590 for (i = 0; i < oldsize; i++) {
591 mutex_exit(&newtable[i].lh_lock);
592 mutex_exit(&oldtable[i].lh_lock);
593 }
594 mutex_exit(&li->li_htlock);
595
596 lretire(li, oldtable, oldsize);
597 }
598
599 /*
600 * Put a lnode in the table
601 */
602 static void
lsave(lnode_t * lp,struct loinfo * li)603 lsave(lnode_t *lp, struct loinfo *li)
604 {
605 ASSERT(lp->lo_vp);
606 ASSERT(MUTEX_HELD(TABLE_LOCK(lp->lo_vp, li)));
607
608 #ifdef LODEBUG
609 lo_dprint(4, "lsave lp %p hash %d\n",
610 lp, ltablehash(lp->lo_vp, li));
611 #endif
612
613 TABLE_COUNT(lp->lo_vp, li)++;
614 lp->lo_next = TABLE_BUCKET(lp->lo_vp, li);
615 TABLE_BUCKET(lp->lo_vp, li) = lp;
616
617 if (li->li_refct > (li->li_htsize << lo_resize_threshold)) {
618 TABLE_LOCK_EXIT(lp->lo_vp, li);
619 lgrow(li, li->li_htsize << lo_resize_factor);
620 TABLE_LOCK_ENTER(lp->lo_vp, li);
621 }
622 }
623
624 /*
625 * Our version of vfs_rele() that stops at 1 instead of 0, and calls
626 * freelfsnode() instead of kmem_free().
627 */
628 static void
lfs_rele(struct lfsnode * lfs,struct loinfo * li)629 lfs_rele(struct lfsnode *lfs, struct loinfo *li)
630 {
631 vfs_t *vfsp = &lfs->lfs_vfs;
632
633 ASSERT(MUTEX_HELD(&li->li_lfslock));
634 ASSERT(vfsp->vfs_count > 1);
635 if (atomic_add_32_nv(&vfsp->vfs_count, -1) == 1)
636 freelfsnode(lfs, li);
637 }
638
639 /*
640 * Remove a lnode from the table
641 */
642 void
freelonode(lnode_t * lp)643 freelonode(lnode_t *lp)
644 {
645 lnode_t *lt;
646 lnode_t *ltprev = NULL;
647 struct lfsnode *lfs, *nextlfs;
648 struct vfs *vfsp;
649 struct vnode *vp = ltov(lp);
650 struct vnode *realvp = realvp(vp);
651 struct loinfo *li = vtoli(vp->v_vfsp);
652
653 #ifdef LODEBUG
654 lo_dprint(4, "freelonode lp %p hash %d\n",
655 lp, ltablehash(lp->lo_vp, li));
656 #endif
657 TABLE_LOCK_ENTER(lp->lo_vp, li);
658
659 mutex_enter(&vp->v_lock);
660 if (vp->v_count > 1) {
661 vp->v_count--; /* release our hold from vn_rele */
662 mutex_exit(&vp->v_lock);
663 TABLE_LOCK_EXIT(lp->lo_vp, li);
664 return;
665 }
666 mutex_exit(&vp->v_lock);
667
668 for (lt = TABLE_BUCKET(lp->lo_vp, li); lt != NULL;
669 ltprev = lt, lt = lt->lo_next) {
670 if (lt == lp) {
671 #ifdef LODEBUG
672 lo_dprint(4, "freeing %p, vfsp %p\n",
673 vp, vp->v_vfsp);
674 #endif
675 atomic_add_32(&li->li_refct, -1);
676 vfsp = vp->v_vfsp;
677 vn_invalid(vp);
678 if (vfsp != li->li_mountvfs) {
679 mutex_enter(&li->li_lfslock);
680 /*
681 * Check for unused lfs
682 */
683 lfs = li->li_lfs;
684 while (lfs != NULL) {
685 nextlfs = lfs->lfs_next;
686 if (vfsp == &lfs->lfs_vfs) {
687 lfs_rele(lfs, li);
688 break;
689 }
690 if (lfs->lfs_vfs.vfs_count == 1) {
691 /*
692 * Lfs is idle
693 */
694 freelfsnode(lfs, li);
695 }
696 lfs = nextlfs;
697 }
698 mutex_exit(&li->li_lfslock);
699 }
700 if (ltprev == NULL) {
701 TABLE_BUCKET(lt->lo_vp, li) = lt->lo_next;
702 } else {
703 ltprev->lo_next = lt->lo_next;
704 }
705 TABLE_COUNT(lt->lo_vp, li)--;
706 TABLE_LOCK_EXIT(lt->lo_vp, li);
707 kmem_cache_free(lnode_cache, lt);
708 vn_free(vp);
709 VN_RELE(realvp);
710 return;
711 }
712 }
713 panic("freelonode");
714 /*NOTREACHED*/
715 }
716
717 /*
718 * Lookup a lnode by vp
719 */
720 static lnode_t *
lfind(struct vnode * vp,struct loinfo * li)721 lfind(struct vnode *vp, struct loinfo *li)
722 {
723 lnode_t *lt;
724
725 ASSERT(MUTEX_HELD(TABLE_LOCK(vp, li)));
726
727 lt = TABLE_BUCKET(vp, li);
728 while (lt != NULL) {
729 if (lt->lo_vp == vp) {
730 VN_HOLD(ltov(lt));
731 return (lt);
732 }
733 lt = lt->lo_next;
734 }
735 return (NULL);
736 }
737
738 #ifdef LODEBUG
739 static int lofsdebug;
740 #endif /* LODEBUG */
741
742 /*
743 * Utilities used by both client and server
744 * Standard levels:
745 * 0) no debugging
746 * 1) hard failures
747 * 2) soft failures
748 * 3) current test software
749 * 4) main procedure entry points
750 * 5) main procedure exit points
751 * 6) utility procedure entry points
752 * 7) utility procedure exit points
753 * 8) obscure procedure entry points
754 * 9) obscure procedure exit points
755 * 10) random stuff
756 * 11) all <= 1
757 * 12) all <= 2
758 * 13) all <= 3
759 * ...
760 */
761
762 #ifdef LODEBUG
763 /*VARARGS2*/
lo_dprint(level,str,a1,a2,a3,a4,a5,a6,a7,a8,a9)764 lo_dprint(level, str, a1, a2, a3, a4, a5, a6, a7, a8, a9)
765 int level;
766 char *str;
767 int a1, a2, a3, a4, a5, a6, a7, a8, a9;
768 {
769
770 if (lofsdebug == level || (lofsdebug > 10 && (lofsdebug - 10) >= level))
771 printf(str, a1, a2, a3, a4, a5, a6, a7, a8, a9);
772 }
773 #endif
774