1 /*-
2 * Copyright (c) 2001, 2002 Ian Dowse. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 */
25
26 /*
27 * This implements a hash-based lookup scheme for UFS directories.
28 */
29
30 #include <sys/cdefs.h>
31 __FBSDID("$FreeBSD$");
32
33 #include "opt_ufs.h"
34
35 #ifdef UFS_DIRHASH
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/kernel.h>
40 #include <sys/lock.h>
41 #include <sys/mutex.h>
42 #include <sys/malloc.h>
43 #include <sys/fnv_hash.h>
44 #include <sys/proc.h>
45 #include <sys/bio.h>
46 #include <sys/buf.h>
47 #include <sys/vnode.h>
48 #include <sys/mount.h>
49 #include <sys/refcount.h>
50 #include <sys/sysctl.h>
51 #include <sys/sx.h>
52 #include <sys/eventhandler.h>
53 #include <sys/time.h>
54 #include <vm/uma.h>
55
56 #include <ufs/ufs/quota.h>
57 #include <ufs/ufs/inode.h>
58 #include <ufs/ufs/dir.h>
59 #include <ufs/ufs/dirhash.h>
60 #include <ufs/ufs/extattr.h>
61 #include <ufs/ufs/ufsmount.h>
62 #include <ufs/ufs/ufs_extern.h>
63
64 #define WRAPINCR(val, limit) (((val) + 1 == (limit)) ? 0 : ((val) + 1))
65 #define WRAPDECR(val, limit) (((val) == 0) ? ((limit) - 1) : ((val) - 1))
66 #define OFSFMT(vp) ((vp)->v_mount->mnt_maxsymlinklen <= 0)
67 #define BLKFREE2IDX(n) ((n) > DH_NFSTATS ? DH_NFSTATS : (n))
68
69 static MALLOC_DEFINE(M_DIRHASH, "ufs_dirhash", "UFS directory hash tables");
70
71 static int ufs_mindirhashsize = DIRBLKSIZ * 5;
72 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_minsize, CTLFLAG_RW,
73 &ufs_mindirhashsize,
74 0, "minimum directory size in bytes for which to use hashed lookup");
75 static int ufs_dirhashmaxmem = 2 * 1024 * 1024; /* NOTE: initial value. It is
76 tuned in ufsdirhash_init() */
77 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_maxmem, CTLFLAG_RW, &ufs_dirhashmaxmem,
78 0, "maximum allowed dirhash memory usage");
79 static int ufs_dirhashmem;
80 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_mem, CTLFLAG_RD, &ufs_dirhashmem,
81 0, "current dirhash memory usage");
82 static int ufs_dirhashcheck = 0;
83 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_docheck, CTLFLAG_RW, &ufs_dirhashcheck,
84 0, "enable extra sanity tests");
85 static int ufs_dirhashlowmemcount = 0;
86 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_lowmemcount, CTLFLAG_RD,
87 &ufs_dirhashlowmemcount, 0, "number of times low memory hook called");
88 static int ufs_dirhashreclaimage = 5;
89 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_reclaimage, CTLFLAG_RW,
90 &ufs_dirhashreclaimage, 0,
91 "max time in seconds of hash inactivity before deletion in low VM events");
92
93
94 static int ufsdirhash_hash(struct dirhash *dh, char *name, int namelen);
95 static void ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff);
96 static void ufsdirhash_delslot(struct dirhash *dh, int slot);
97 static int ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen,
98 doff_t offset);
99 static doff_t ufsdirhash_getprev(struct direct *dp, doff_t offset);
100 static int ufsdirhash_recycle(int wanted);
101 static void ufsdirhash_lowmem(void);
102 static void ufsdirhash_free_locked(struct inode *ip);
103
104 static uma_zone_t ufsdirhash_zone;
105
106 #define DIRHASHLIST_LOCK() mtx_lock(&ufsdirhash_mtx)
107 #define DIRHASHLIST_UNLOCK() mtx_unlock(&ufsdirhash_mtx)
108 #define DIRHASH_BLKALLOC_WAITOK() uma_zalloc(ufsdirhash_zone, M_WAITOK)
109 #define DIRHASH_BLKFREE(ptr) uma_zfree(ufsdirhash_zone, (ptr))
110 #define DIRHASH_ASSERT_LOCKED(dh) \
111 sx_assert(&(dh)->dh_lock, SA_LOCKED)
112
113 /* Dirhash list; recently-used entries are near the tail. */
114 static TAILQ_HEAD(, dirhash) ufsdirhash_list;
115
116 /* Protects: ufsdirhash_list, `dh_list' field, ufs_dirhashmem. */
117 static struct mtx ufsdirhash_mtx;
118
119 /*
120 * Locking:
121 *
122 * The relationship between inode and dirhash is protected either by an
123 * exclusive vnode lock or the vnode interlock where a shared vnode lock
124 * may be used. The dirhash_mtx is acquired after the dirhash lock. To
125 * handle teardown races, code wishing to lock the dirhash for an inode
126 * when using a shared vnode lock must obtain a private reference on the
127 * dirhash while holding the vnode interlock. They can drop it once they
128 * have obtained the dirhash lock and verified that the dirhash wasn't
129 * recycled while they waited for the dirhash lock.
130 *
131 * ufsdirhash_build() acquires a shared lock on the dirhash when it is
132 * successful. This lock is released after a call to ufsdirhash_lookup().
133 *
134 * Functions requiring exclusive access use ufsdirhash_acquire() which may
135 * free a dirhash structure that was recycled by ufsdirhash_recycle().
136 *
137 * The dirhash lock may be held across io operations.
138 *
139 * WITNESS reports a lock order reversal between the "bufwait" lock
140 * and the "dirhash" lock. However, this specific reversal will not
141 * cause a deadlock. To get a deadlock, one would have to lock a
142 * buffer followed by the dirhash while a second thread locked a
143 * buffer while holding the dirhash lock. The second order can happen
144 * under a shared or exclusive vnode lock for the associated directory
145 * in lookup(). The first order, however, can only happen under an
146 * exclusive vnode lock (e.g. unlink(), rename(), etc.). Thus, for
147 * a thread to be doing a "bufwait" -> "dirhash" order, it has to hold
148 * an exclusive vnode lock. That exclusive vnode lock will prevent
149 * any other threads from doing a "dirhash" -> "bufwait" order.
150 */
151
152 static void
153 ufsdirhash_hold(struct dirhash *dh)
154 {
155
156 refcount_acquire(&dh->dh_refcount);
157 }
158
159 static void
160 ufsdirhash_drop(struct dirhash *dh)
161 {
162
163 if (refcount_release(&dh->dh_refcount)) {
164 sx_destroy(&dh->dh_lock);
165 free(dh, M_DIRHASH);
166 }
167 }
168
169 /*
170 * Release the lock on a dirhash.
171 */
172 static void
173 ufsdirhash_release(struct dirhash *dh)
174 {
175
176 sx_unlock(&dh->dh_lock);
177 }
178
179 /*
180 * Either acquire an existing hash locked shared or create a new hash and
181 * return it exclusively locked. May return NULL if the allocation fails.
182 *
183 * The vnode interlock is used to protect the i_dirhash pointer from
184 * simultaneous access while only a shared vnode lock is held.
185 */
186 static struct dirhash *
187 ufsdirhash_create(struct inode *ip)
188 {
189 struct dirhash *ndh;
190 struct dirhash *dh;
191 struct vnode *vp;
192 int error;
193
194 error = 0;
195 ndh = dh = NULL;
196 vp = ip->i_vnode;
197 for (;;) {
198 /* Racy check for i_dirhash to prefetch a dirhash structure. */
199 if (ip->i_dirhash == NULL && ndh == NULL) {
200 ndh = malloc(sizeof *dh, M_DIRHASH,
201 M_NOWAIT | M_ZERO);
202 if (ndh == NULL)
203 return (NULL);
204 refcount_init(&ndh->dh_refcount, 1);
205
206 /*
207 * The DUPOK is to prevent warnings from the
208 * sx_slock() a few lines down which is safe
209 * since the duplicate lock in that case is
210 * the one for this dirhash we are creating
211 * now which has no external references until
212 * after this function returns.
213 */
214 sx_init_flags(&ndh->dh_lock, "dirhash", SX_DUPOK);
215 sx_xlock(&ndh->dh_lock);
216 }
217 /*
218 * Check i_dirhash. If it's NULL just try to use a
219 * preallocated structure. If none exists loop and try again.
220 */
221 VI_LOCK(vp);
222 dh = ip->i_dirhash;
223 if (dh == NULL) {
224 ip->i_dirhash = ndh;
225 VI_UNLOCK(vp);
226 if (ndh == NULL)
227 continue;
228 return (ndh);
229 }
230 ufsdirhash_hold(dh);
231 VI_UNLOCK(vp);
232
233 /* Acquire a shared lock on existing hashes. */
234 sx_slock(&dh->dh_lock);
235
236 /* The hash could've been recycled while we were waiting. */
237 VI_LOCK(vp);
238 if (ip->i_dirhash != dh) {
239 VI_UNLOCK(vp);
240 ufsdirhash_release(dh);
241 ufsdirhash_drop(dh);
242 continue;
243 }
244 VI_UNLOCK(vp);
245 ufsdirhash_drop(dh);
246
247 /* If the hash is still valid we've succeeded. */
248 if (dh->dh_hash != NULL)
249 break;
250 /*
251 * If the hash is NULL it has been recycled. Try to upgrade
252 * so we can recreate it. If we fail the upgrade, drop our
253 * lock and try again.
254 */
255 if (sx_try_upgrade(&dh->dh_lock))
256 break;
257 sx_sunlock(&dh->dh_lock);
258 }
259 /* Free the preallocated structure if it was not necessary. */
260 if (ndh) {
261 ufsdirhash_release(ndh);
262 ufsdirhash_drop(ndh);
263 }
264 return (dh);
265 }
266
267 /*
268 * Acquire an exclusive lock on an existing hash. Requires an exclusive
269 * vnode lock to protect the i_dirhash pointer. hashes that have been
270 * recycled are reclaimed here and NULL is returned.
271 */
272 static struct dirhash *
273 ufsdirhash_acquire(struct inode *ip)
274 {
275 struct dirhash *dh;
276 struct vnode *vp;
277
278 ASSERT_VOP_ELOCKED(ip->i_vnode, __FUNCTION__);
279
280 vp = ip->i_vnode;
281 dh = ip->i_dirhash;
282 if (dh == NULL)
283 return (NULL);
284 sx_xlock(&dh->dh_lock);
285 if (dh->dh_hash != NULL)
286 return (dh);
287 ufsdirhash_free_locked(ip);
288 return (NULL);
289 }
290
291 /*
292 * Acquire exclusively and free the hash pointed to by ip. Works with a
293 * shared or exclusive vnode lock.
294 */
295 void
296 ufsdirhash_free(struct inode *ip)
297 {
298 struct dirhash *dh;
299 struct vnode *vp;
300
301 vp = ip->i_vnode;
302 for (;;) {
303 /* Grab a reference on this inode's dirhash if it has one. */
304 VI_LOCK(vp);
305 dh = ip->i_dirhash;
306 if (dh == NULL) {
307 VI_UNLOCK(vp);
308 return;
309 }
310 ufsdirhash_hold(dh);
311 VI_UNLOCK(vp);
312
313 /* Exclusively lock the dirhash. */
314 sx_xlock(&dh->dh_lock);
315
316 /* If this dirhash still belongs to this inode, then free it. */
317 VI_LOCK(vp);
318 if (ip->i_dirhash == dh) {
319 VI_UNLOCK(vp);
320 ufsdirhash_drop(dh);
321 break;
322 }
323 VI_UNLOCK(vp);
324
325 /*
326 * This inode's dirhash has changed while we were
327 * waiting for the dirhash lock, so try again.
328 */
329 ufsdirhash_release(dh);
330 ufsdirhash_drop(dh);
331 }
332 ufsdirhash_free_locked(ip);
333 }
334
335 /*
336 * Attempt to build up a hash table for the directory contents in
337 * inode 'ip'. Returns 0 on success, or -1 of the operation failed.
338 */
339 int
340 ufsdirhash_build(struct inode *ip)
341 {
342 struct dirhash *dh;
343 struct buf *bp = NULL;
344 struct direct *ep;
345 struct vnode *vp;
346 doff_t bmask, pos;
347 int dirblocks, i, j, memreqd, nblocks, narrays, nslots, slot;
348
349 /* Take care of a decreased sysctl value. */
350 while (ufs_dirhashmem > ufs_dirhashmaxmem) {
351 if (ufsdirhash_recycle(0) != 0)
352 return (-1);
353 /* Recycled enough memory, so unlock the list. */
354 DIRHASHLIST_UNLOCK();
355 }
356
357 /* Check if we can/should use dirhash. */
358 if (ip->i_size < ufs_mindirhashsize || OFSFMT(ip->i_vnode) ||
359 ip->i_effnlink == 0) {
360 if (ip->i_dirhash)
361 ufsdirhash_free(ip);
362 return (-1);
363 }
364 dh = ufsdirhash_create(ip);
365 if (dh == NULL)
366 return (-1);
367 if (dh->dh_hash != NULL)
368 return (0);
369
370 vp = ip->i_vnode;
371 /* Allocate 50% more entries than this dir size could ever need. */
372 KASSERT(ip->i_size >= DIRBLKSIZ, ("ufsdirhash_build size"));
373 nslots = ip->i_size / DIRECTSIZ(1);
374 nslots = (nslots * 3 + 1) / 2;
375 narrays = howmany(nslots, DH_NBLKOFF);
376 nslots = narrays * DH_NBLKOFF;
377 dirblocks = howmany(ip->i_size, DIRBLKSIZ);
378 nblocks = (dirblocks * 3 + 1) / 2;
379 memreqd = sizeof(*dh) + narrays * sizeof(*dh->dh_hash) +
380 narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) +
381 nblocks * sizeof(*dh->dh_blkfree);
382 DIRHASHLIST_LOCK();
383 if (memreqd + ufs_dirhashmem > ufs_dirhashmaxmem) {
384 DIRHASHLIST_UNLOCK();
385 if (memreqd > ufs_dirhashmaxmem / 2)
386 goto fail;
387 /* Try to free some space. */
388 if (ufsdirhash_recycle(memreqd) != 0)
389 goto fail;
390 /* Enough was freed, and list has been locked. */
391 }
392 ufs_dirhashmem += memreqd;
393 DIRHASHLIST_UNLOCK();
394
395 /* Initialise the hash table and block statistics. */
396 dh->dh_memreq = memreqd;
397 dh->dh_narrays = narrays;
398 dh->dh_hlen = nslots;
399 dh->dh_nblk = nblocks;
400 dh->dh_dirblks = dirblocks;
401 for (i = 0; i < DH_NFSTATS; i++)
402 dh->dh_firstfree[i] = -1;
403 dh->dh_firstfree[DH_NFSTATS] = 0;
404 dh->dh_hused = 0;
405 dh->dh_seqoff = -1;
406 dh->dh_score = DH_SCOREINIT;
407 dh->dh_lastused = time_second;
408
409 /*
410 * Use non-blocking mallocs so that we will revert to a linear
411 * lookup on failure rather than potentially blocking forever.
412 */
413 dh->dh_hash = malloc(narrays * sizeof(dh->dh_hash[0]),
414 M_DIRHASH, M_NOWAIT | M_ZERO);
415 if (dh->dh_hash == NULL)
416 goto fail;
417 dh->dh_blkfree = malloc(nblocks * sizeof(dh->dh_blkfree[0]),
418 M_DIRHASH, M_NOWAIT);
419 if (dh->dh_blkfree == NULL)
420 goto fail;
421 for (i = 0; i < narrays; i++) {
422 if ((dh->dh_hash[i] = DIRHASH_BLKALLOC_WAITOK()) == NULL)
423 goto fail;
424 for (j = 0; j < DH_NBLKOFF; j++)
425 dh->dh_hash[i][j] = DIRHASH_EMPTY;
426 }
427 for (i = 0; i < dirblocks; i++)
428 dh->dh_blkfree[i] = DIRBLKSIZ / DIRALIGN;
429 bmask = vp->v_mount->mnt_stat.f_iosize - 1;
430 pos = 0;
431 while (pos < ip->i_size) {
432 /* If necessary, get the next directory block. */
433 if ((pos & bmask) == 0) {
434 if (bp != NULL)
435 brelse(bp);
436 if (UFS_BLKATOFF(vp, (off_t)pos, NULL, &bp) != 0)
437 goto fail;
438 }
439
440 /* Add this entry to the hash. */
441 ep = (struct direct *)((char *)bp->b_data + (pos & bmask));
442 if (ep->d_reclen == 0 || ep->d_reclen >
443 DIRBLKSIZ - (pos & (DIRBLKSIZ - 1))) {
444 /* Corrupted directory. */
445 brelse(bp);
446 goto fail;
447 }
448 if (ep->d_ino != 0) {
449 /* Add the entry (simplified ufsdirhash_add). */
450 slot = ufsdirhash_hash(dh, ep->d_name, ep->d_namlen);
451 while (DH_ENTRY(dh, slot) != DIRHASH_EMPTY)
452 slot = WRAPINCR(slot, dh->dh_hlen);
453 dh->dh_hused++;
454 DH_ENTRY(dh, slot) = pos;
455 ufsdirhash_adjfree(dh, pos, -DIRSIZ(0, ep));
456 }
457 pos += ep->d_reclen;
458 }
459
460 if (bp != NULL)
461 brelse(bp);
462 DIRHASHLIST_LOCK();
463 TAILQ_INSERT_TAIL(&ufsdirhash_list, dh, dh_list);
464 dh->dh_onlist = 1;
465 DIRHASHLIST_UNLOCK();
466 sx_downgrade(&dh->dh_lock);
467 return (0);
468
469 fail:
470 ufsdirhash_free_locked(ip);
471 return (-1);
472 }
473
474 /*
475 * Free any hash table associated with inode 'ip'.
476 */
477 static void
478 ufsdirhash_free_locked(struct inode *ip)
479 {
480 struct dirhash *dh;
481 struct vnode *vp;
482 int i;
483
484 DIRHASH_ASSERT_LOCKED(ip->i_dirhash);
485
486 /*
487 * Clear the pointer in the inode to prevent new threads from
488 * finding the dead structure.
489 */
490 vp = ip->i_vnode;
491 VI_LOCK(vp);
492 dh = ip->i_dirhash;
493 ip->i_dirhash = NULL;
494 VI_UNLOCK(vp);
495
496 /*
497 * Remove the hash from the list since we are going to free its
498 * memory.
499 */
500 DIRHASHLIST_LOCK();
501 if (dh->dh_onlist)
502 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list);
503 ufs_dirhashmem -= dh->dh_memreq;
504 DIRHASHLIST_UNLOCK();
505
506 /*
507 * At this point, any waiters for the lock should hold their
508 * own reference on the dirhash structure. They will drop
509 * that reference once they grab the vnode interlock and see
510 * that ip->i_dirhash is NULL.
511 */
512 sx_xunlock(&dh->dh_lock);
513
514 /*
515 * Handle partially recycled as well as fully constructed hashes.
516 */
517 if (dh->dh_hash != NULL) {
518 for (i = 0; i < dh->dh_narrays; i++)
519 if (dh->dh_hash[i] != NULL)
520 DIRHASH_BLKFREE(dh->dh_hash[i]);
521 free(dh->dh_hash, M_DIRHASH);
522 if (dh->dh_blkfree != NULL)
523 free(dh->dh_blkfree, M_DIRHASH);
524 }
525
526 /*
527 * Drop the inode's reference to the data structure.
528 */
529 ufsdirhash_drop(dh);
530 }
531
532 /*
533 * Find the offset of the specified name within the given inode.
534 * Returns 0 on success, ENOENT if the entry does not exist, or
535 * EJUSTRETURN if the caller should revert to a linear search.
536 *
537 * If successful, the directory offset is stored in *offp, and a
538 * pointer to a struct buf containing the entry is stored in *bpp. If
539 * prevoffp is non-NULL, the offset of the previous entry within
540 * the DIRBLKSIZ-sized block is stored in *prevoffp (if the entry
541 * is the first in a block, the start of the block is used).
542 *
543 * Must be called with the hash locked. Returns with the hash unlocked.
544 */
545 int
546 ufsdirhash_lookup(struct inode *ip, char *name, int namelen, doff_t *offp,
547 struct buf **bpp, doff_t *prevoffp)
548 {
549 struct dirhash *dh, *dh_next;
550 struct direct *dp;
551 struct vnode *vp;
552 struct buf *bp;
553 doff_t blkoff, bmask, offset, prevoff, seqoff;
554 int i, slot;
555 int error;
556
557 dh = ip->i_dirhash;
558 KASSERT(dh != NULL && dh->dh_hash != NULL,
559 ("ufsdirhash_lookup: Invalid dirhash %p\n", dh));
560 DIRHASH_ASSERT_LOCKED(dh);
561 /*
562 * Move this dirhash towards the end of the list if it has a
563 * score higher than the next entry, and acquire the dh_lock.
564 */
565 DIRHASHLIST_LOCK();
566 if (TAILQ_NEXT(dh, dh_list) != NULL) {
567 /*
568 * If the new score will be greater than that of the next
569 * entry, then move this entry past it. With both mutexes
570 * held, dh_next won't go away, but its dh_score could
571 * change; that's not important since it is just a hint.
572 */
573 if ((dh_next = TAILQ_NEXT(dh, dh_list)) != NULL &&
574 dh->dh_score >= dh_next->dh_score) {
575 KASSERT(dh->dh_onlist, ("dirhash: not on list"));
576 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list);
577 TAILQ_INSERT_AFTER(&ufsdirhash_list, dh_next, dh,
578 dh_list);
579 }
580 }
581 /* Update the score. */
582 if (dh->dh_score < DH_SCOREMAX)
583 dh->dh_score++;
584
585 /* Update last used time. */
586 dh->dh_lastused = time_second;
587 DIRHASHLIST_UNLOCK();
588
589 vp = ip->i_vnode;
590 bmask = vp->v_mount->mnt_stat.f_iosize - 1;
591 blkoff = -1;
592 bp = NULL;
593 seqoff = dh->dh_seqoff;
594 restart:
595 slot = ufsdirhash_hash(dh, name, namelen);
596
597 if (seqoff != -1) {
598 /*
599 * Sequential access optimisation. seqoff contains the
600 * offset of the directory entry immediately following
601 * the last entry that was looked up. Check if this offset
602 * appears in the hash chain for the name we are looking for.
603 */
604 for (i = slot; (offset = DH_ENTRY(dh, i)) != DIRHASH_EMPTY;
605 i = WRAPINCR(i, dh->dh_hlen))
606 if (offset == seqoff)
607 break;
608 if (offset == seqoff) {
609 /*
610 * We found an entry with the expected offset. This
611 * is probably the entry we want, but if not, the
612 * code below will retry.
613 */
614 slot = i;
615 } else
616 seqoff = -1;
617 }
618
619 for (; (offset = DH_ENTRY(dh, slot)) != DIRHASH_EMPTY;
620 slot = WRAPINCR(slot, dh->dh_hlen)) {
621 if (offset == DIRHASH_DEL)
622 continue;
623 if (offset < 0 || offset >= ip->i_size)
624 panic("ufsdirhash_lookup: bad offset in hash array");
625 if ((offset & ~bmask) != blkoff) {
626 if (bp != NULL)
627 brelse(bp);
628 blkoff = offset & ~bmask;
629 if (UFS_BLKATOFF(vp, (off_t)blkoff, NULL, &bp) != 0) {
630 error = EJUSTRETURN;
631 goto fail;
632 }
633 }
634 KASSERT(bp != NULL, ("no buffer allocated"));
635 dp = (struct direct *)(bp->b_data + (offset & bmask));
636 if (dp->d_reclen == 0 || dp->d_reclen >
637 DIRBLKSIZ - (offset & (DIRBLKSIZ - 1))) {
638 /* Corrupted directory. */
639 error = EJUSTRETURN;
640 goto fail;
641 }
642 if (dp->d_namlen == namelen &&
643 bcmp(dp->d_name, name, namelen) == 0) {
644 /* Found. Get the prev offset if needed. */
645 if (prevoffp != NULL) {
646 if (offset & (DIRBLKSIZ - 1)) {
647 prevoff = ufsdirhash_getprev(dp,
648 offset);
649 if (prevoff == -1) {
650 error = EJUSTRETURN;
651 goto fail;
652 }
653 } else
654 prevoff = offset;
655 *prevoffp = prevoff;
656 }
657
658 /* Update offset. */
659 dh->dh_seqoff = offset + DIRSIZ(0, dp);
660 *bpp = bp;
661 *offp = offset;
662 ufsdirhash_release(dh);
663 return (0);
664 }
665
666 /*
667 * When the name doesn't match in the sequential
668 * optimization case, go back and search normally.
669 */
670 if (seqoff != -1) {
671 seqoff = -1;
672 goto restart;
673 }
674 }
675 error = ENOENT;
676 fail:
677 ufsdirhash_release(dh);
678 if (bp != NULL)
679 brelse(bp);
680 return (error);
681 }
682
683 /*
684 * Find a directory block with room for 'slotneeded' bytes. Returns
685 * the offset of the directory entry that begins the free space.
686 * This will either be the offset of an existing entry that has free
687 * space at the end, or the offset of an entry with d_ino == 0 at
688 * the start of a DIRBLKSIZ block.
689 *
690 * To use the space, the caller may need to compact existing entries in
691 * the directory. The total number of bytes in all of the entries involved
692 * in the compaction is stored in *slotsize. In other words, all of
693 * the entries that must be compacted are exactly contained in the
694 * region beginning at the returned offset and spanning *slotsize bytes.
695 *
696 * Returns -1 if no space was found, indicating that the directory
697 * must be extended.
698 */
699 doff_t
700 ufsdirhash_findfree(struct inode *ip, int slotneeded, int *slotsize)
701 {
702 struct direct *dp;
703 struct dirhash *dh;
704 struct buf *bp;
705 doff_t pos, slotstart;
706 int dirblock, error, freebytes, i;
707
708 dh = ip->i_dirhash;
709 KASSERT(dh != NULL && dh->dh_hash != NULL,
710 ("ufsdirhash_findfree: Invalid dirhash %p\n", dh));
711 DIRHASH_ASSERT_LOCKED(dh);
712
713 /* Find a directory block with the desired free space. */
714 dirblock = -1;
715 for (i = howmany(slotneeded, DIRALIGN); i <= DH_NFSTATS; i++)
716 if ((dirblock = dh->dh_firstfree[i]) != -1)
717 break;
718 if (dirblock == -1)
719 return (-1);
720
721 KASSERT(dirblock < dh->dh_nblk &&
722 dh->dh_blkfree[dirblock] >= howmany(slotneeded, DIRALIGN),
723 ("ufsdirhash_findfree: bad stats"));
724 pos = dirblock * DIRBLKSIZ;
725 error = UFS_BLKATOFF(ip->i_vnode, (off_t)pos, (char **)&dp, &bp);
726 if (error)
727 return (-1);
728
729 /* Find the first entry with free space. */
730 for (i = 0; i < DIRBLKSIZ; ) {
731 if (dp->d_reclen == 0) {
732 brelse(bp);
733 return (-1);
734 }
735 if (dp->d_ino == 0 || dp->d_reclen > DIRSIZ(0, dp))
736 break;
737 i += dp->d_reclen;
738 dp = (struct direct *)((char *)dp + dp->d_reclen);
739 }
740 if (i > DIRBLKSIZ) {
741 brelse(bp);
742 return (-1);
743 }
744 slotstart = pos + i;
745
746 /* Find the range of entries needed to get enough space */
747 freebytes = 0;
748 while (i < DIRBLKSIZ && freebytes < slotneeded) {
749 freebytes += dp->d_reclen;
750 if (dp->d_ino != 0)
751 freebytes -= DIRSIZ(0, dp);
752 if (dp->d_reclen == 0) {
753 brelse(bp);
754 return (-1);
755 }
756 i += dp->d_reclen;
757 dp = (struct direct *)((char *)dp + dp->d_reclen);
758 }
759 if (i > DIRBLKSIZ) {
760 brelse(bp);
761 return (-1);
762 }
763 if (freebytes < slotneeded)
764 panic("ufsdirhash_findfree: free mismatch");
765 brelse(bp);
766 *slotsize = pos + i - slotstart;
767 return (slotstart);
768 }
769
770 /*
771 * Return the start of the unused space at the end of a directory, or
772 * -1 if there are no trailing unused blocks.
773 */
774 doff_t
775 ufsdirhash_enduseful(struct inode *ip)
776 {
777
778 struct dirhash *dh;
779 int i;
780
781 dh = ip->i_dirhash;
782 DIRHASH_ASSERT_LOCKED(dh);
783 KASSERT(dh != NULL && dh->dh_hash != NULL,
784 ("ufsdirhash_enduseful: Invalid dirhash %p\n", dh));
785
786 if (dh->dh_blkfree[dh->dh_dirblks - 1] != DIRBLKSIZ / DIRALIGN)
787 return (-1);
788
789 for (i = dh->dh_dirblks - 1; i >= 0; i--)
790 if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN)
791 break;
792
793 return ((doff_t)(i + 1) * DIRBLKSIZ);
794 }
795
796 /*
797 * Insert information into the hash about a new directory entry. dirp
798 * points to a struct direct containing the entry, and offset specifies
799 * the offset of this entry.
800 */
801 void
802 ufsdirhash_add(struct inode *ip, struct direct *dirp, doff_t offset)
803 {
804 struct dirhash *dh;
805 int slot;
806
807 if ((dh = ufsdirhash_acquire(ip)) == NULL)
808 return;
809
810 KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ,
811 ("ufsdirhash_add: bad offset"));
812 /*
813 * Normal hash usage is < 66%. If the usage gets too high then
814 * remove the hash entirely and let it be rebuilt later.
815 */
816 if (dh->dh_hused >= (dh->dh_hlen * 3) / 4) {
817 ufsdirhash_free_locked(ip);
818 return;
819 }
820
821 /* Find a free hash slot (empty or deleted), and add the entry. */
822 slot = ufsdirhash_hash(dh, dirp->d_name, dirp->d_namlen);
823 while (DH_ENTRY(dh, slot) >= 0)
824 slot = WRAPINCR(slot, dh->dh_hlen);
825 if (DH_ENTRY(dh, slot) == DIRHASH_EMPTY)
826 dh->dh_hused++;
827 DH_ENTRY(dh, slot) = offset;
828
829 /* Update last used time. */
830 dh->dh_lastused = time_second;
831
832 /* Update the per-block summary info. */
833 ufsdirhash_adjfree(dh, offset, -DIRSIZ(0, dirp));
834 ufsdirhash_release(dh);
835 }
836
837 /*
838 * Remove the specified directory entry from the hash. The entry to remove
839 * is defined by the name in `dirp', which must exist at the specified
840 * `offset' within the directory.
841 */
842 void
843 ufsdirhash_remove(struct inode *ip, struct direct *dirp, doff_t offset)
844 {
845 struct dirhash *dh;
846 int slot;
847
848 if ((dh = ufsdirhash_acquire(ip)) == NULL)
849 return;
850
851 KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ,
852 ("ufsdirhash_remove: bad offset"));
853 /* Find the entry */
854 slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, offset);
855
856 /* Remove the hash entry. */
857 ufsdirhash_delslot(dh, slot);
858
859 /* Update the per-block summary info. */
860 ufsdirhash_adjfree(dh, offset, DIRSIZ(0, dirp));
861 ufsdirhash_release(dh);
862 }
863
864 /*
865 * Change the offset associated with a directory entry in the hash. Used
866 * when compacting directory blocks.
867 */
868 void
869 ufsdirhash_move(struct inode *ip, struct direct *dirp, doff_t oldoff,
870 doff_t newoff)
871 {
872 struct dirhash *dh;
873 int slot;
874
875 if ((dh = ufsdirhash_acquire(ip)) == NULL)
876 return;
877
878 KASSERT(oldoff < dh->dh_dirblks * DIRBLKSIZ &&
879 newoff < dh->dh_dirblks * DIRBLKSIZ,
880 ("ufsdirhash_move: bad offset"));
881 /* Find the entry, and update the offset. */
882 slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, oldoff);
883 DH_ENTRY(dh, slot) = newoff;
884 ufsdirhash_release(dh);
885 }
886
887 /*
888 * Inform dirhash that the directory has grown by one block that
889 * begins at offset (i.e. the new length is offset + DIRBLKSIZ).
890 */
891 void
892 ufsdirhash_newblk(struct inode *ip, doff_t offset)
893 {
894 struct dirhash *dh;
895 int block;
896
897 if ((dh = ufsdirhash_acquire(ip)) == NULL)
898 return;
899
900 KASSERT(offset == dh->dh_dirblks * DIRBLKSIZ,
901 ("ufsdirhash_newblk: bad offset"));
902 block = offset / DIRBLKSIZ;
903 if (block >= dh->dh_nblk) {
904 /* Out of space; must rebuild. */
905 ufsdirhash_free_locked(ip);
906 return;
907 }
908 dh->dh_dirblks = block + 1;
909
910 /* Account for the new free block. */
911 dh->dh_blkfree[block] = DIRBLKSIZ / DIRALIGN;
912 if (dh->dh_firstfree[DH_NFSTATS] == -1)
913 dh->dh_firstfree[DH_NFSTATS] = block;
914 ufsdirhash_release(dh);
915 }
916
917 /*
918 * Inform dirhash that the directory is being truncated.
919 */
920 void
921 ufsdirhash_dirtrunc(struct inode *ip, doff_t offset)
922 {
923 struct dirhash *dh;
924 int block, i;
925
926 if ((dh = ufsdirhash_acquire(ip)) == NULL)
927 return;
928
929 KASSERT(offset <= dh->dh_dirblks * DIRBLKSIZ,
930 ("ufsdirhash_dirtrunc: bad offset"));
931 block = howmany(offset, DIRBLKSIZ);
932 /*
933 * If the directory shrinks to less than 1/8 of dh_nblk blocks
934 * (about 20% of its original size due to the 50% extra added in
935 * ufsdirhash_build) then free it, and let the caller rebuild
936 * if necessary.
937 */
938 if (block < dh->dh_nblk / 8 && dh->dh_narrays > 1) {
939 ufsdirhash_free_locked(ip);
940 return;
941 }
942
943 /*
944 * Remove any `first free' information pertaining to the
945 * truncated blocks. All blocks we're removing should be
946 * completely unused.
947 */
948 if (dh->dh_firstfree[DH_NFSTATS] >= block)
949 dh->dh_firstfree[DH_NFSTATS] = -1;
950 for (i = block; i < dh->dh_dirblks; i++)
951 if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN)
952 panic("ufsdirhash_dirtrunc: blocks in use");
953 for (i = 0; i < DH_NFSTATS; i++)
954 if (dh->dh_firstfree[i] >= block)
955 panic("ufsdirhash_dirtrunc: first free corrupt");
956 dh->dh_dirblks = block;
957 ufsdirhash_release(dh);
958 }
959
960 /*
961 * Debugging function to check that the dirhash information about
962 * a directory block matches its actual contents. Panics if a mismatch
963 * is detected.
964 *
965 * On entry, `buf' should point to the start of an in-core
966 * DIRBLKSIZ-sized directory block, and `offset' should contain the
967 * offset from the start of the directory of that block.
968 */
969 void
970 ufsdirhash_checkblock(struct inode *ip, char *buf, doff_t offset)
971 {
972 struct dirhash *dh;
973 struct direct *dp;
974 int block, ffslot, i, nfree;
975
976 if (!ufs_dirhashcheck)
977 return;
978 if ((dh = ufsdirhash_acquire(ip)) == NULL)
979 return;
980
981 block = offset / DIRBLKSIZ;
982 if ((offset & (DIRBLKSIZ - 1)) != 0 || block >= dh->dh_dirblks)
983 panic("ufsdirhash_checkblock: bad offset");
984
985 nfree = 0;
986 for (i = 0; i < DIRBLKSIZ; i += dp->d_reclen) {
987 dp = (struct direct *)(buf + i);
988 if (dp->d_reclen == 0 || i + dp->d_reclen > DIRBLKSIZ)
989 panic("ufsdirhash_checkblock: bad dir");
990
991 if (dp->d_ino == 0) {
992 #if 0
993 /*
994 * XXX entries with d_ino == 0 should only occur
995 * at the start of a DIRBLKSIZ block. However the
996 * ufs code is tolerant of such entries at other
997 * offsets, and fsck does not fix them.
998 */
999 if (i != 0)
1000 panic("ufsdirhash_checkblock: bad dir inode");
1001 #endif
1002 nfree += dp->d_reclen;
1003 continue;
1004 }
1005
1006 /* Check that the entry exists (will panic if it doesn't). */
1007 ufsdirhash_findslot(dh, dp->d_name, dp->d_namlen, offset + i);
1008
1009 nfree += dp->d_reclen - DIRSIZ(0, dp);
1010 }
1011 if (i != DIRBLKSIZ)
1012 panic("ufsdirhash_checkblock: bad dir end");
1013
1014 if (dh->dh_blkfree[block] * DIRALIGN != nfree)
1015 panic("ufsdirhash_checkblock: bad free count");
1016
1017 ffslot = BLKFREE2IDX(nfree / DIRALIGN);
1018 for (i = 0; i <= DH_NFSTATS; i++)
1019 if (dh->dh_firstfree[i] == block && i != ffslot)
1020 panic("ufsdirhash_checkblock: bad first-free");
1021 if (dh->dh_firstfree[ffslot] == -1)
1022 panic("ufsdirhash_checkblock: missing first-free entry");
1023 ufsdirhash_release(dh);
1024 }
1025
1026 /*
1027 * Hash the specified filename into a dirhash slot.
1028 */
1029 static int
1030 ufsdirhash_hash(struct dirhash *dh, char *name, int namelen)
1031 {
1032 u_int32_t hash;
1033
1034 /*
1035 * We hash the name and then some other bit of data that is
1036 * invariant over the dirhash's lifetime. Otherwise names
1037 * differing only in the last byte are placed close to one
1038 * another in the table, which is bad for linear probing.
1039 */
1040 hash = fnv_32_buf(name, namelen, FNV1_32_INIT);
1041 hash = fnv_32_buf(&dh, sizeof(dh), hash);
1042 return (hash % dh->dh_hlen);
1043 }
1044
1045 /*
1046 * Adjust the number of free bytes in the block containing `offset'
1047 * by the value specified by `diff'.
1048 *
1049 * The caller must ensure we have exclusive access to `dh'; normally
1050 * that means that dh_lock should be held, but this is also called
1051 * from ufsdirhash_build() where exclusive access can be assumed.
1052 */
1053 static void
1054 ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff)
1055 {
1056 int block, i, nfidx, ofidx;
1057
1058 /* Update the per-block summary info. */
1059 block = offset / DIRBLKSIZ;
1060 KASSERT(block < dh->dh_nblk && block < dh->dh_dirblks,
1061 ("dirhash bad offset"));
1062 ofidx = BLKFREE2IDX(dh->dh_blkfree[block]);
1063 dh->dh_blkfree[block] = (int)dh->dh_blkfree[block] + (diff / DIRALIGN);
1064 nfidx = BLKFREE2IDX(dh->dh_blkfree[block]);
1065
1066 /* Update the `first free' list if necessary. */
1067 if (ofidx != nfidx) {
1068 /* If removing, scan forward for the next block. */
1069 if (dh->dh_firstfree[ofidx] == block) {
1070 for (i = block + 1; i < dh->dh_dirblks; i++)
1071 if (BLKFREE2IDX(dh->dh_blkfree[i]) == ofidx)
1072 break;
1073 dh->dh_firstfree[ofidx] = (i < dh->dh_dirblks) ? i : -1;
1074 }
1075
1076 /* Make this the new `first free' if necessary */
1077 if (dh->dh_firstfree[nfidx] > block ||
1078 dh->dh_firstfree[nfidx] == -1)
1079 dh->dh_firstfree[nfidx] = block;
1080 }
1081 }
1082
1083 /*
1084 * Find the specified name which should have the specified offset.
1085 * Returns a slot number, and panics on failure.
1086 *
1087 * `dh' must be locked on entry and remains so on return.
1088 */
1089 static int
1090 ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, doff_t offset)
1091 {
1092 int slot;
1093
1094 DIRHASH_ASSERT_LOCKED(dh);
1095
1096 /* Find the entry. */
1097 KASSERT(dh->dh_hused < dh->dh_hlen, ("dirhash find full"));
1098 slot = ufsdirhash_hash(dh, name, namelen);
1099 while (DH_ENTRY(dh, slot) != offset &&
1100 DH_ENTRY(dh, slot) != DIRHASH_EMPTY)
1101 slot = WRAPINCR(slot, dh->dh_hlen);
1102 if (DH_ENTRY(dh, slot) != offset)
1103 panic("ufsdirhash_findslot: '%.*s' not found", namelen, name);
1104
1105 return (slot);
1106 }
1107
1108 /*
1109 * Remove the entry corresponding to the specified slot from the hash array.
1110 *
1111 * `dh' must be locked on entry and remains so on return.
1112 */
1113 static void
1114 ufsdirhash_delslot(struct dirhash *dh, int slot)
1115 {
1116 int i;
1117
1118 DIRHASH_ASSERT_LOCKED(dh);
1119
1120 /* Mark the entry as deleted. */
1121 DH_ENTRY(dh, slot) = DIRHASH_DEL;
1122
1123 /* If this is the end of a chain of DIRHASH_DEL slots, remove them. */
1124 for (i = slot; DH_ENTRY(dh, i) == DIRHASH_DEL; )
1125 i = WRAPINCR(i, dh->dh_hlen);
1126 if (DH_ENTRY(dh, i) == DIRHASH_EMPTY) {
1127 i = WRAPDECR(i, dh->dh_hlen);
1128 while (DH_ENTRY(dh, i) == DIRHASH_DEL) {
1129 DH_ENTRY(dh, i) = DIRHASH_EMPTY;
1130 dh->dh_hused--;
1131 i = WRAPDECR(i, dh->dh_hlen);
1132 }
1133 KASSERT(dh->dh_hused >= 0, ("ufsdirhash_delslot neg hlen"));
1134 }
1135 }
1136
1137 /*
1138 * Given a directory entry and its offset, find the offset of the
1139 * previous entry in the same DIRBLKSIZ-sized block. Returns an
1140 * offset, or -1 if there is no previous entry in the block or some
1141 * other problem occurred.
1142 */
1143 static doff_t
1144 ufsdirhash_getprev(struct direct *dirp, doff_t offset)
1145 {
1146 struct direct *dp;
1147 char *blkbuf;
1148 doff_t blkoff, prevoff;
1149 int entrypos, i;
1150
1151 blkoff = offset & ~(DIRBLKSIZ - 1); /* offset of start of block */
1152 entrypos = offset & (DIRBLKSIZ - 1); /* entry relative to block */
1153 blkbuf = (char *)dirp - entrypos;
1154 prevoff = blkoff;
1155
1156 /* If `offset' is the start of a block, there is no previous entry. */
1157 if (entrypos == 0)
1158 return (-1);
1159
1160 /* Scan from the start of the block until we get to the entry. */
1161 for (i = 0; i < entrypos; i += dp->d_reclen) {
1162 dp = (struct direct *)(blkbuf + i);
1163 if (dp->d_reclen == 0 || i + dp->d_reclen > entrypos)
1164 return (-1); /* Corrupted directory. */
1165 prevoff = blkoff + i;
1166 }
1167 return (prevoff);
1168 }
1169
1170 /*
1171 * Delete the given dirhash and reclaim its memory. Assumes that
1172 * ufsdirhash_list is locked, and leaves it locked. Also assumes
1173 * that dh is locked. Returns the amount of memory freed.
1174 */
1175 static int
1176 ufsdirhash_destroy(struct dirhash *dh)
1177 {
1178 doff_t **hash;
1179 u_int8_t *blkfree;
1180 int i, mem, narrays;
1181
1182 KASSERT(dh->dh_hash != NULL, ("dirhash: NULL hash on list"));
1183
1184 /* Remove it from the list and detach its memory. */
1185 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list);
1186 dh->dh_onlist = 0;
1187 hash = dh->dh_hash;
1188 dh->dh_hash = NULL;
1189 blkfree = dh->dh_blkfree;
1190 dh->dh_blkfree = NULL;
1191 narrays = dh->dh_narrays;
1192 mem = dh->dh_memreq;
1193 dh->dh_memreq = 0;
1194
1195 /* Unlock dirhash and free the detached memory. */
1196 ufsdirhash_release(dh);
1197 for (i = 0; i < narrays; i++)
1198 DIRHASH_BLKFREE(hash[i]);
1199 free(hash, M_DIRHASH);
1200 free(blkfree, M_DIRHASH);
1201
1202 /* Account for the returned memory. */
1203 ufs_dirhashmem -= mem;
1204
1205 return (mem);
1206 }
1207
1208 /*
1209 * Try to free up `wanted' bytes by stealing memory from existing
1210 * dirhashes. Returns zero with list locked if successful.
1211 */
1212 static int
1213 ufsdirhash_recycle(int wanted)
1214 {
1215 struct dirhash *dh;
1216
1217 DIRHASHLIST_LOCK();
1218 dh = TAILQ_FIRST(&ufsdirhash_list);
1219 while (wanted + ufs_dirhashmem > ufs_dirhashmaxmem) {
1220 /* Decrement the score; only recycle if it becomes zero. */
1221 if (dh == NULL || --dh->dh_score > 0) {
1222 DIRHASHLIST_UNLOCK();
1223 return (-1);
1224 }
1225 /*
1226 * If we can't lock it it's in use and we don't want to
1227 * recycle it anyway.
1228 */
1229 if (!sx_try_xlock(&dh->dh_lock)) {
1230 dh = TAILQ_NEXT(dh, dh_list);
1231 continue;
1232 }
1233
1234 ufsdirhash_destroy(dh);
1235
1236 /* Repeat if necessary. */
1237 dh = TAILQ_FIRST(&ufsdirhash_list);
1238 }
1239 /* Success; return with list locked. */
1240 return (0);
1241 }
1242
1243 /*
1244 * Callback that frees some dirhashes when the system is low on virtual memory.
1245 */
1246 static void
1247 ufsdirhash_lowmem()
1248 {
1249 struct dirhash *dh, *dh_temp;
1250 int memfreed = 0;
1251 /* XXX: this 10% may need to be adjusted */
1252 int memwanted = ufs_dirhashmem / 10;
1253
1254 ufs_dirhashlowmemcount++;
1255
1256 DIRHASHLIST_LOCK();
1257 /*
1258 * Delete dirhashes not used for more than ufs_dirhashreclaimage
1259 * seconds. If we can't get a lock on the dirhash, it will be skipped.
1260 */
1261 TAILQ_FOREACH_SAFE(dh, &ufsdirhash_list, dh_list, dh_temp) {
1262 if (!sx_try_xlock(&dh->dh_lock))
1263 continue;
1264 if (time_second - dh->dh_lastused > ufs_dirhashreclaimage)
1265 memfreed += ufsdirhash_destroy(dh);
1266 /* Unlock if we didn't delete the dirhash */
1267 else
1268 ufsdirhash_release(dh);
1269 }
1270
1271 /*
1272 * If not enough memory was freed, keep deleting hashes from the head
1273 * of the dirhash list. The ones closest to the head should be the
1274 * oldest.
1275 */
1276 if (memfreed < memwanted) {
1277 TAILQ_FOREACH_SAFE(dh, &ufsdirhash_list, dh_list, dh_temp) {
1278 if (!sx_try_xlock(&dh->dh_lock))
1279 continue;
1280 memfreed += ufsdirhash_destroy(dh);
1281 if (memfreed >= memwanted)
1282 break;
1283 }
1284 }
1285 DIRHASHLIST_UNLOCK();
1286 }
1287
1288
1289 void
1290 ufsdirhash_init()
1291 {
1292 ufs_dirhashmaxmem = lmax(roundup(hibufspace / 64, PAGE_SIZE),
1293 2 * 1024 * 1024);
1294
1295 ufsdirhash_zone = uma_zcreate("DIRHASH", DH_NBLKOFF * sizeof(doff_t),
1296 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
1297 mtx_init(&ufsdirhash_mtx, "dirhash list", NULL, MTX_DEF);
1298 TAILQ_INIT(&ufsdirhash_list);
1299
1300 /* Register a callback function to handle low memory signals */
1301 EVENTHANDLER_REGISTER(vm_lowmem, ufsdirhash_lowmem, NULL,
1302 EVENTHANDLER_PRI_FIRST);
1303 }
1304
1305 void
1306 ufsdirhash_uninit()
1307 {
1308 KASSERT(TAILQ_EMPTY(&ufsdirhash_list), ("ufsdirhash_uninit"));
1309 uma_zdestroy(ufsdirhash_zone);
1310 mtx_destroy(&ufsdirhash_mtx);
1311 }
1312
1313 #endif /* UFS_DIRHASH */
Cache object: 58cf36b24fa2aa9069a7c1501ccea890
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