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: releng/5.2/sys/ufs/ufs/ufs_dirhash.c 116192 2003-06-11 06:34:30Z obrien $");
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/sysctl.h>
50 #include <vm/uma.h>
51
52 #include <ufs/ufs/quota.h>
53 #include <ufs/ufs/inode.h>
54 #include <ufs/ufs/dir.h>
55 #include <ufs/ufs/dirhash.h>
56 #include <ufs/ufs/extattr.h>
57 #include <ufs/ufs/ufsmount.h>
58 #include <ufs/ufs/ufs_extern.h>
59
60 #define WRAPINCR(val, limit) (((val) + 1 == (limit)) ? 0 : ((val) + 1))
61 #define WRAPDECR(val, limit) (((val) == 0) ? ((limit) - 1) : ((val) - 1))
62 #define OFSFMT(vp) ((vp)->v_mount->mnt_maxsymlinklen <= 0)
63 #define BLKFREE2IDX(n) ((n) > DH_NFSTATS ? DH_NFSTATS : (n))
64
65 static MALLOC_DEFINE(M_DIRHASH, "UFS dirhash", "UFS directory hash tables");
66
67 SYSCTL_NODE(_vfs, OID_AUTO, ufs, CTLFLAG_RD, 0, "UFS filesystem");
68
69 static int ufs_mindirhashsize = DIRBLKSIZ * 5;
70 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_minsize, CTLFLAG_RW,
71 &ufs_mindirhashsize,
72 0, "minimum directory size in bytes for which to use hashed lookup");
73 static int ufs_dirhashmaxmem = 2 * 1024 * 1024;
74 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_maxmem, CTLFLAG_RW, &ufs_dirhashmaxmem,
75 0, "maximum allowed dirhash memory usage");
76 static int ufs_dirhashmem;
77 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_mem, CTLFLAG_RD, &ufs_dirhashmem,
78 0, "current dirhash memory usage");
79 static int ufs_dirhashcheck = 0;
80 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_docheck, CTLFLAG_RW, &ufs_dirhashcheck,
81 0, "enable extra sanity tests");
82
83
84 static int ufsdirhash_hash(struct dirhash *dh, char *name, int namelen);
85 static void ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff);
86 static void ufsdirhash_delslot(struct dirhash *dh, int slot);
87 static int ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen,
88 doff_t offset);
89 static doff_t ufsdirhash_getprev(struct direct *dp, doff_t offset);
90 static int ufsdirhash_recycle(int wanted);
91
92 static uma_zone_t ufsdirhash_zone;
93
94 /* Dirhash list; recently-used entries are near the tail. */
95 static TAILQ_HEAD(, dirhash) ufsdirhash_list;
96
97 /* Protects: ufsdirhash_list, `dh_list' field, ufs_dirhashmem. */
98 static struct mtx ufsdirhash_mtx;
99
100 /*
101 * Locking order:
102 * ufsdirhash_mtx
103 * dh_mtx
104 *
105 * The dh_mtx mutex should be acquired either via the inode lock, or via
106 * ufsdirhash_mtx. Only the owner of the inode may free the associated
107 * dirhash, but anything can steal its memory and set dh_hash to NULL.
108 */
109
110 /*
111 * Attempt to build up a hash table for the directory contents in
112 * inode 'ip'. Returns 0 on success, or -1 of the operation failed.
113 */
114 int
115 ufsdirhash_build(struct inode *ip)
116 {
117 struct dirhash *dh;
118 struct buf *bp = NULL;
119 struct direct *ep;
120 struct vnode *vp;
121 doff_t bmask, pos;
122 int dirblocks, i, j, memreqd, nblocks, narrays, nslots, slot;
123
124 /* Check if we can/should use dirhash. */
125 if (ip->i_dirhash == NULL) {
126 if (ip->i_size < ufs_mindirhashsize || OFSFMT(ip->i_vnode))
127 return (-1);
128 } else {
129 /* Hash exists, but sysctls could have changed. */
130 if (ip->i_size < ufs_mindirhashsize ||
131 ufs_dirhashmem > ufs_dirhashmaxmem) {
132 ufsdirhash_free(ip);
133 return (-1);
134 }
135 /* Check if hash exists and is intact (note: unlocked read). */
136 if (ip->i_dirhash->dh_hash != NULL)
137 return (0);
138 /* Free the old, recycled hash and build a new one. */
139 ufsdirhash_free(ip);
140 }
141
142 /* Don't hash removed directories. */
143 if (ip->i_effnlink == 0)
144 return (-1);
145
146 vp = ip->i_vnode;
147 /* Allocate 50% more entries than this dir size could ever need. */
148 KASSERT(ip->i_size >= DIRBLKSIZ, ("ufsdirhash_build size"));
149 nslots = ip->i_size / DIRECTSIZ(1);
150 nslots = (nslots * 3 + 1) / 2;
151 narrays = howmany(nslots, DH_NBLKOFF);
152 nslots = narrays * DH_NBLKOFF;
153 dirblocks = howmany(ip->i_size, DIRBLKSIZ);
154 nblocks = (dirblocks * 3 + 1) / 2;
155
156 memreqd = sizeof(*dh) + narrays * sizeof(*dh->dh_hash) +
157 narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) +
158 nblocks * sizeof(*dh->dh_blkfree);
159 mtx_lock(&ufsdirhash_mtx);
160 if (memreqd + ufs_dirhashmem > ufs_dirhashmaxmem) {
161 mtx_unlock(&ufsdirhash_mtx);
162 if (memreqd > ufs_dirhashmaxmem / 2)
163 return (-1);
164
165 /* Try to free some space. */
166 if (ufsdirhash_recycle(memreqd) != 0)
167 return (-1);
168 /* Enough was freed, and ufsdirhash_mtx has been locked. */
169 }
170 ufs_dirhashmem += memreqd;
171 mtx_unlock(&ufsdirhash_mtx);
172
173 /*
174 * Use non-blocking mallocs so that we will revert to a linear
175 * lookup on failure rather than potentially blocking forever.
176 */
177 MALLOC(dh, struct dirhash *, sizeof *dh, M_DIRHASH, M_NOWAIT | M_ZERO);
178 if (dh == NULL) {
179 mtx_lock(&ufsdirhash_mtx);
180 ufs_dirhashmem -= memreqd;
181 mtx_unlock(&ufsdirhash_mtx);
182 return (-1);
183 }
184 MALLOC(dh->dh_hash, doff_t **, narrays * sizeof(dh->dh_hash[0]),
185 M_DIRHASH, M_NOWAIT | M_ZERO);
186 MALLOC(dh->dh_blkfree, u_int8_t *, nblocks * sizeof(dh->dh_blkfree[0]),
187 M_DIRHASH, M_NOWAIT);
188 if (dh->dh_hash == NULL || dh->dh_blkfree == NULL)
189 goto fail;
190 for (i = 0; i < narrays; i++) {
191 if ((dh->dh_hash[i] = uma_zalloc(ufsdirhash_zone,
192 M_WAITOK)) == NULL)
193 goto fail;
194 for (j = 0; j < DH_NBLKOFF; j++)
195 dh->dh_hash[i][j] = DIRHASH_EMPTY;
196 }
197
198 /* Initialise the hash table and block statistics. */
199 mtx_init(&dh->dh_mtx, "dirhash", NULL, MTX_DEF);
200 dh->dh_narrays = narrays;
201 dh->dh_hlen = nslots;
202 dh->dh_nblk = nblocks;
203 dh->dh_dirblks = dirblocks;
204 for (i = 0; i < dirblocks; i++)
205 dh->dh_blkfree[i] = DIRBLKSIZ / DIRALIGN;
206 for (i = 0; i < DH_NFSTATS; i++)
207 dh->dh_firstfree[i] = -1;
208 dh->dh_firstfree[DH_NFSTATS] = 0;
209 dh->dh_seqopt = 0;
210 dh->dh_seqoff = 0;
211 dh->dh_score = DH_SCOREINIT;
212 ip->i_dirhash = dh;
213
214 bmask = VFSTOUFS(vp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
215 pos = 0;
216 while (pos < ip->i_size) {
217 /* If necessary, get the next directory block. */
218 if ((pos & bmask) == 0) {
219 if (bp != NULL)
220 brelse(bp);
221 if (UFS_BLKATOFF(vp, (off_t)pos, NULL, &bp) != 0)
222 goto fail;
223 }
224
225 /* Add this entry to the hash. */
226 ep = (struct direct *)((char *)bp->b_data + (pos & bmask));
227 if (ep->d_reclen == 0 || ep->d_reclen >
228 DIRBLKSIZ - (pos & (DIRBLKSIZ - 1))) {
229 /* Corrupted directory. */
230 brelse(bp);
231 goto fail;
232 }
233 if (ep->d_ino != 0) {
234 /* Add the entry (simplified ufsdirhash_add). */
235 slot = ufsdirhash_hash(dh, ep->d_name, ep->d_namlen);
236 while (DH_ENTRY(dh, slot) != DIRHASH_EMPTY)
237 slot = WRAPINCR(slot, dh->dh_hlen);
238 dh->dh_hused++;
239 DH_ENTRY(dh, slot) = pos;
240 ufsdirhash_adjfree(dh, pos, -DIRSIZ(0, ep));
241 }
242 pos += ep->d_reclen;
243 }
244
245 if (bp != NULL)
246 brelse(bp);
247 mtx_lock(&ufsdirhash_mtx);
248 TAILQ_INSERT_TAIL(&ufsdirhash_list, dh, dh_list);
249 dh->dh_onlist = 1;
250 mtx_unlock(&ufsdirhash_mtx);
251 return (0);
252
253 fail:
254 if (dh->dh_hash != NULL) {
255 for (i = 0; i < narrays; i++)
256 if (dh->dh_hash[i] != NULL)
257 uma_zfree(ufsdirhash_zone, dh->dh_hash[i]);
258 FREE(dh->dh_hash, M_DIRHASH);
259 }
260 if (dh->dh_blkfree != NULL)
261 FREE(dh->dh_blkfree, M_DIRHASH);
262 FREE(dh, M_DIRHASH);
263 ip->i_dirhash = NULL;
264 mtx_lock(&ufsdirhash_mtx);
265 ufs_dirhashmem -= memreqd;
266 mtx_unlock(&ufsdirhash_mtx);
267 return (-1);
268 }
269
270 /*
271 * Free any hash table associated with inode 'ip'.
272 */
273 void
274 ufsdirhash_free(struct inode *ip)
275 {
276 struct dirhash *dh;
277 int i, mem;
278
279 if ((dh = ip->i_dirhash) == NULL)
280 return;
281 mtx_lock(&ufsdirhash_mtx);
282 mtx_lock(&dh->dh_mtx);
283 if (dh->dh_onlist)
284 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list);
285 mtx_unlock(&dh->dh_mtx);
286 mtx_unlock(&ufsdirhash_mtx);
287
288 /* The dirhash pointed to by 'dh' is exclusively ours now. */
289
290 mem = sizeof(*dh);
291 if (dh->dh_hash != NULL) {
292 for (i = 0; i < dh->dh_narrays; i++)
293 uma_zfree(ufsdirhash_zone, dh->dh_hash[i]);
294 FREE(dh->dh_hash, M_DIRHASH);
295 FREE(dh->dh_blkfree, M_DIRHASH);
296 mem += dh->dh_narrays * sizeof(*dh->dh_hash) +
297 dh->dh_narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) +
298 dh->dh_nblk * sizeof(*dh->dh_blkfree);
299 }
300 mtx_destroy(&dh->dh_mtx);
301 FREE(dh, M_DIRHASH);
302 ip->i_dirhash = NULL;
303
304 mtx_lock(&ufsdirhash_mtx);
305 ufs_dirhashmem -= mem;
306 mtx_unlock(&ufsdirhash_mtx);
307 }
308
309 /*
310 * Find the offset of the specified name within the given inode.
311 * Returns 0 on success, ENOENT if the entry does not exist, or
312 * EJUSTRETURN if the caller should revert to a linear search.
313 *
314 * If successful, the directory offset is stored in *offp, and a
315 * pointer to a struct buf containing the entry is stored in *bpp. If
316 * prevoffp is non-NULL, the offset of the previous entry within
317 * the DIRBLKSIZ-sized block is stored in *prevoffp (if the entry
318 * is the first in a block, the start of the block is used).
319 */
320 int
321 ufsdirhash_lookup(struct inode *ip, char *name, int namelen, doff_t *offp,
322 struct buf **bpp, doff_t *prevoffp)
323 {
324 struct dirhash *dh, *dh_next;
325 struct direct *dp;
326 struct vnode *vp;
327 struct buf *bp;
328 doff_t blkoff, bmask, offset, prevoff;
329 int i, slot;
330
331 if ((dh = ip->i_dirhash) == NULL)
332 return (EJUSTRETURN);
333 /*
334 * Move this dirhash towards the end of the list if it has a
335 * score higher than the next entry, and acquire the dh_mtx.
336 * Optimise the case where it's already the last by performing
337 * an unlocked read of the TAILQ_NEXT pointer.
338 *
339 * In both cases, end up holding just dh_mtx.
340 */
341 if (TAILQ_NEXT(dh, dh_list) != NULL) {
342 mtx_lock(&ufsdirhash_mtx);
343 mtx_lock(&dh->dh_mtx);
344 /*
345 * If the new score will be greater than that of the next
346 * entry, then move this entry past it. With both mutexes
347 * held, dh_next won't go away, but its dh_score could
348 * change; that's not important since it is just a hint.
349 */
350 if (dh->dh_hash != NULL &&
351 (dh_next = TAILQ_NEXT(dh, dh_list)) != NULL &&
352 dh->dh_score >= dh_next->dh_score) {
353 KASSERT(dh->dh_onlist, ("dirhash: not on list"));
354 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list);
355 TAILQ_INSERT_AFTER(&ufsdirhash_list, dh_next, dh,
356 dh_list);
357 }
358 mtx_unlock(&ufsdirhash_mtx);
359 } else {
360 /* Already the last, though that could change as we wait. */
361 mtx_lock(&dh->dh_mtx);
362 }
363 if (dh->dh_hash == NULL) {
364 mtx_unlock(&dh->dh_mtx);
365 ufsdirhash_free(ip);
366 return (EJUSTRETURN);
367 }
368
369 /* Update the score. */
370 if (dh->dh_score < DH_SCOREMAX)
371 dh->dh_score++;
372
373 vp = ip->i_vnode;
374 bmask = VFSTOUFS(vp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
375 blkoff = -1;
376 bp = NULL;
377 restart:
378 slot = ufsdirhash_hash(dh, name, namelen);
379
380 if (dh->dh_seqopt) {
381 /*
382 * Sequential access optimisation. dh_seqoff contains the
383 * offset of the directory entry immediately following
384 * the last entry that was looked up. Check if this offset
385 * appears in the hash chain for the name we are looking for.
386 */
387 for (i = slot; (offset = DH_ENTRY(dh, i)) != DIRHASH_EMPTY;
388 i = WRAPINCR(i, dh->dh_hlen))
389 if (offset == dh->dh_seqoff)
390 break;
391 if (offset == dh->dh_seqoff) {
392 /*
393 * We found an entry with the expected offset. This
394 * is probably the entry we want, but if not, the
395 * code below will turn off seqoff and retry.
396 */
397 slot = i;
398 } else
399 dh->dh_seqopt = 0;
400 }
401
402 for (; (offset = DH_ENTRY(dh, slot)) != DIRHASH_EMPTY;
403 slot = WRAPINCR(slot, dh->dh_hlen)) {
404 if (offset == DIRHASH_DEL)
405 continue;
406 mtx_unlock(&dh->dh_mtx);
407
408 if (offset < 0 || offset >= ip->i_size)
409 panic("ufsdirhash_lookup: bad offset in hash array");
410 if ((offset & ~bmask) != blkoff) {
411 if (bp != NULL)
412 brelse(bp);
413 blkoff = offset & ~bmask;
414 if (UFS_BLKATOFF(vp, (off_t)blkoff, NULL, &bp) != 0)
415 return (EJUSTRETURN);
416 }
417 dp = (struct direct *)(bp->b_data + (offset & bmask));
418 if (dp->d_reclen == 0 || dp->d_reclen >
419 DIRBLKSIZ - (offset & (DIRBLKSIZ - 1))) {
420 /* Corrupted directory. */
421 brelse(bp);
422 return (EJUSTRETURN);
423 }
424 if (dp->d_namlen == namelen &&
425 bcmp(dp->d_name, name, namelen) == 0) {
426 /* Found. Get the prev offset if needed. */
427 if (prevoffp != NULL) {
428 if (offset & (DIRBLKSIZ - 1)) {
429 prevoff = ufsdirhash_getprev(dp,
430 offset);
431 if (prevoff == -1) {
432 brelse(bp);
433 return (EJUSTRETURN);
434 }
435 } else
436 prevoff = offset;
437 *prevoffp = prevoff;
438 }
439
440 /* Check for sequential access, and update offset. */
441 if (dh->dh_seqopt == 0 && dh->dh_seqoff == offset)
442 dh->dh_seqopt = 1;
443 dh->dh_seqoff = offset + DIRSIZ(0, dp);
444
445 *bpp = bp;
446 *offp = offset;
447 return (0);
448 }
449
450 mtx_lock(&dh->dh_mtx);
451 if (dh->dh_hash == NULL) {
452 mtx_unlock(&dh->dh_mtx);
453 if (bp != NULL)
454 brelse(bp);
455 ufsdirhash_free(ip);
456 return (EJUSTRETURN);
457 }
458 /*
459 * When the name doesn't match in the seqopt case, go back
460 * and search normally.
461 */
462 if (dh->dh_seqopt) {
463 dh->dh_seqopt = 0;
464 goto restart;
465 }
466 }
467 mtx_unlock(&dh->dh_mtx);
468 if (bp != NULL)
469 brelse(bp);
470 return (ENOENT);
471 }
472
473 /*
474 * Find a directory block with room for 'slotneeded' bytes. Returns
475 * the offset of the directory entry that begins the free space.
476 * This will either be the offset of an existing entry that has free
477 * space at the end, or the offset of an entry with d_ino == 0 at
478 * the start of a DIRBLKSIZ block.
479 *
480 * To use the space, the caller may need to compact existing entries in
481 * the directory. The total number of bytes in all of the entries involved
482 * in the compaction is stored in *slotsize. In other words, all of
483 * the entries that must be compacted are exactly contained in the
484 * region beginning at the returned offset and spanning *slotsize bytes.
485 *
486 * Returns -1 if no space was found, indicating that the directory
487 * must be extended.
488 */
489 doff_t
490 ufsdirhash_findfree(struct inode *ip, int slotneeded, int *slotsize)
491 {
492 struct direct *dp;
493 struct dirhash *dh;
494 struct buf *bp;
495 doff_t pos, slotstart;
496 int dirblock, error, freebytes, i;
497
498 if ((dh = ip->i_dirhash) == NULL)
499 return (-1);
500 mtx_lock(&dh->dh_mtx);
501 if (dh->dh_hash == NULL) {
502 mtx_unlock(&dh->dh_mtx);
503 ufsdirhash_free(ip);
504 return (-1);
505 }
506
507 /* Find a directory block with the desired free space. */
508 dirblock = -1;
509 for (i = howmany(slotneeded, DIRALIGN); i <= DH_NFSTATS; i++)
510 if ((dirblock = dh->dh_firstfree[i]) != -1)
511 break;
512 if (dirblock == -1) {
513 mtx_unlock(&dh->dh_mtx);
514 return (-1);
515 }
516
517 KASSERT(dirblock < dh->dh_nblk &&
518 dh->dh_blkfree[dirblock] >= howmany(slotneeded, DIRALIGN),
519 ("ufsdirhash_findfree: bad stats"));
520 mtx_unlock(&dh->dh_mtx);
521 pos = dirblock * DIRBLKSIZ;
522 error = UFS_BLKATOFF(ip->i_vnode, (off_t)pos, (char **)&dp, &bp);
523 if (error)
524 return (-1);
525
526 /* Find the first entry with free space. */
527 for (i = 0; i < DIRBLKSIZ; ) {
528 if (dp->d_reclen == 0) {
529 brelse(bp);
530 return (-1);
531 }
532 if (dp->d_ino == 0 || dp->d_reclen > DIRSIZ(0, dp))
533 break;
534 i += dp->d_reclen;
535 dp = (struct direct *)((char *)dp + dp->d_reclen);
536 }
537 if (i > DIRBLKSIZ) {
538 brelse(bp);
539 return (-1);
540 }
541 slotstart = pos + i;
542
543 /* Find the range of entries needed to get enough space */
544 freebytes = 0;
545 while (i < DIRBLKSIZ && freebytes < slotneeded) {
546 freebytes += dp->d_reclen;
547 if (dp->d_ino != 0)
548 freebytes -= DIRSIZ(0, dp);
549 if (dp->d_reclen == 0) {
550 brelse(bp);
551 return (-1);
552 }
553 i += dp->d_reclen;
554 dp = (struct direct *)((char *)dp + dp->d_reclen);
555 }
556 if (i > DIRBLKSIZ) {
557 brelse(bp);
558 return (-1);
559 }
560 if (freebytes < slotneeded)
561 panic("ufsdirhash_findfree: free mismatch");
562 brelse(bp);
563 *slotsize = pos + i - slotstart;
564 return (slotstart);
565 }
566
567 /*
568 * Return the start of the unused space at the end of a directory, or
569 * -1 if there are no trailing unused blocks.
570 */
571 doff_t
572 ufsdirhash_enduseful(struct inode *ip)
573 {
574
575 struct dirhash *dh;
576 int i;
577
578 if ((dh = ip->i_dirhash) == NULL)
579 return (-1);
580 mtx_lock(&dh->dh_mtx);
581 if (dh->dh_hash == NULL) {
582 mtx_unlock(&dh->dh_mtx);
583 ufsdirhash_free(ip);
584 return (-1);
585 }
586
587 if (dh->dh_blkfree[dh->dh_dirblks - 1] != DIRBLKSIZ / DIRALIGN) {
588 mtx_unlock(&dh->dh_mtx);
589 return (-1);
590 }
591
592 for (i = dh->dh_dirblks - 1; i >= 0; i--)
593 if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN)
594 break;
595 mtx_unlock(&dh->dh_mtx);
596 return ((doff_t)(i + 1) * DIRBLKSIZ);
597 }
598
599 /*
600 * Insert information into the hash about a new directory entry. dirp
601 * points to a struct direct containing the entry, and offset specifies
602 * the offset of this entry.
603 */
604 void
605 ufsdirhash_add(struct inode *ip, struct direct *dirp, doff_t offset)
606 {
607 struct dirhash *dh;
608 int slot;
609
610 if ((dh = ip->i_dirhash) == NULL)
611 return;
612 mtx_lock(&dh->dh_mtx);
613 if (dh->dh_hash == NULL) {
614 mtx_unlock(&dh->dh_mtx);
615 ufsdirhash_free(ip);
616 return;
617 }
618
619 KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ,
620 ("ufsdirhash_add: bad offset"));
621 /*
622 * Normal hash usage is < 66%. If the usage gets too high then
623 * remove the hash entirely and let it be rebuilt later.
624 */
625 if (dh->dh_hused >= (dh->dh_hlen * 3) / 4) {
626 mtx_unlock(&dh->dh_mtx);
627 ufsdirhash_free(ip);
628 return;
629 }
630
631 /* Find a free hash slot (empty or deleted), and add the entry. */
632 slot = ufsdirhash_hash(dh, dirp->d_name, dirp->d_namlen);
633 while (DH_ENTRY(dh, slot) >= 0)
634 slot = WRAPINCR(slot, dh->dh_hlen);
635 if (DH_ENTRY(dh, slot) == DIRHASH_EMPTY)
636 dh->dh_hused++;
637 DH_ENTRY(dh, slot) = offset;
638
639 /* Update the per-block summary info. */
640 ufsdirhash_adjfree(dh, offset, -DIRSIZ(0, dirp));
641 mtx_unlock(&dh->dh_mtx);
642 }
643
644 /*
645 * Remove the specified directory entry from the hash. The entry to remove
646 * is defined by the name in `dirp', which must exist at the specified
647 * `offset' within the directory.
648 */
649 void
650 ufsdirhash_remove(struct inode *ip, struct direct *dirp, doff_t offset)
651 {
652 struct dirhash *dh;
653 int slot;
654
655 if ((dh = ip->i_dirhash) == NULL)
656 return;
657 mtx_lock(&dh->dh_mtx);
658 if (dh->dh_hash == NULL) {
659 mtx_unlock(&dh->dh_mtx);
660 ufsdirhash_free(ip);
661 return;
662 }
663
664 KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ,
665 ("ufsdirhash_remove: bad offset"));
666 /* Find the entry */
667 slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, offset);
668
669 /* Remove the hash entry. */
670 ufsdirhash_delslot(dh, slot);
671
672 /* Update the per-block summary info. */
673 ufsdirhash_adjfree(dh, offset, DIRSIZ(0, dirp));
674 mtx_unlock(&dh->dh_mtx);
675 }
676
677 /*
678 * Change the offset associated with a directory entry in the hash. Used
679 * when compacting directory blocks.
680 */
681 void
682 ufsdirhash_move(struct inode *ip, struct direct *dirp, doff_t oldoff,
683 doff_t newoff)
684 {
685 struct dirhash *dh;
686 int slot;
687
688 if ((dh = ip->i_dirhash) == NULL)
689 return;
690 mtx_lock(&dh->dh_mtx);
691 if (dh->dh_hash == NULL) {
692 mtx_unlock(&dh->dh_mtx);
693 ufsdirhash_free(ip);
694 return;
695 }
696
697 KASSERT(oldoff < dh->dh_dirblks * DIRBLKSIZ &&
698 newoff < dh->dh_dirblks * DIRBLKSIZ,
699 ("ufsdirhash_move: bad offset"));
700 /* Find the entry, and update the offset. */
701 slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, oldoff);
702 DH_ENTRY(dh, slot) = newoff;
703 mtx_unlock(&dh->dh_mtx);
704 }
705
706 /*
707 * Inform dirhash that the directory has grown by one block that
708 * begins at offset (i.e. the new length is offset + DIRBLKSIZ).
709 */
710 void
711 ufsdirhash_newblk(struct inode *ip, doff_t offset)
712 {
713 struct dirhash *dh;
714 int block;
715
716 if ((dh = ip->i_dirhash) == NULL)
717 return;
718 mtx_lock(&dh->dh_mtx);
719 if (dh->dh_hash == NULL) {
720 mtx_unlock(&dh->dh_mtx);
721 ufsdirhash_free(ip);
722 return;
723 }
724
725 KASSERT(offset == dh->dh_dirblks * DIRBLKSIZ,
726 ("ufsdirhash_newblk: bad offset"));
727 block = offset / DIRBLKSIZ;
728 if (block >= dh->dh_nblk) {
729 /* Out of space; must rebuild. */
730 mtx_unlock(&dh->dh_mtx);
731 ufsdirhash_free(ip);
732 return;
733 }
734 dh->dh_dirblks = block + 1;
735
736 /* Account for the new free block. */
737 dh->dh_blkfree[block] = DIRBLKSIZ / DIRALIGN;
738 if (dh->dh_firstfree[DH_NFSTATS] == -1)
739 dh->dh_firstfree[DH_NFSTATS] = block;
740 mtx_unlock(&dh->dh_mtx);
741 }
742
743 /*
744 * Inform dirhash that the directory is being truncated.
745 */
746 void
747 ufsdirhash_dirtrunc(struct inode *ip, doff_t offset)
748 {
749 struct dirhash *dh;
750 int block, i;
751
752 if ((dh = ip->i_dirhash) == NULL)
753 return;
754 mtx_lock(&dh->dh_mtx);
755 if (dh->dh_hash == NULL) {
756 mtx_unlock(&dh->dh_mtx);
757 ufsdirhash_free(ip);
758 return;
759 }
760
761 KASSERT(offset <= dh->dh_dirblks * DIRBLKSIZ,
762 ("ufsdirhash_dirtrunc: bad offset"));
763 block = howmany(offset, DIRBLKSIZ);
764 /*
765 * If the directory shrinks to less than 1/8 of dh_nblk blocks
766 * (about 20% of its original size due to the 50% extra added in
767 * ufsdirhash_build) then free it, and let the caller rebuild
768 * if necessary.
769 */
770 if (block < dh->dh_nblk / 8 && dh->dh_narrays > 1) {
771 mtx_unlock(&dh->dh_mtx);
772 ufsdirhash_free(ip);
773 return;
774 }
775
776 /*
777 * Remove any `first free' information pertaining to the
778 * truncated blocks. All blocks we're removing should be
779 * completely unused.
780 */
781 if (dh->dh_firstfree[DH_NFSTATS] >= block)
782 dh->dh_firstfree[DH_NFSTATS] = -1;
783 for (i = block; i < dh->dh_dirblks; i++)
784 if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN)
785 panic("ufsdirhash_dirtrunc: blocks in use");
786 for (i = 0; i < DH_NFSTATS; i++)
787 if (dh->dh_firstfree[i] >= block)
788 panic("ufsdirhash_dirtrunc: first free corrupt");
789 dh->dh_dirblks = block;
790 mtx_unlock(&dh->dh_mtx);
791 }
792
793 /*
794 * Debugging function to check that the dirhash information about
795 * a directory block matches its actual contents. Panics if a mismatch
796 * is detected.
797 *
798 * On entry, `buf' should point to the start of an in-core
799 * DIRBLKSIZ-sized directory block, and `offset' should contain the
800 * offset from the start of the directory of that block.
801 */
802 void
803 ufsdirhash_checkblock(struct inode *ip, char *buf, doff_t offset)
804 {
805 struct dirhash *dh;
806 struct direct *dp;
807 int block, ffslot, i, nfree;
808
809 if (!ufs_dirhashcheck)
810 return;
811 if ((dh = ip->i_dirhash) == NULL)
812 return;
813 mtx_lock(&dh->dh_mtx);
814 if (dh->dh_hash == NULL) {
815 mtx_unlock(&dh->dh_mtx);
816 ufsdirhash_free(ip);
817 return;
818 }
819
820 block = offset / DIRBLKSIZ;
821 if ((offset & (DIRBLKSIZ - 1)) != 0 || block >= dh->dh_dirblks)
822 panic("ufsdirhash_checkblock: bad offset");
823
824 nfree = 0;
825 for (i = 0; i < DIRBLKSIZ; i += dp->d_reclen) {
826 dp = (struct direct *)(buf + i);
827 if (dp->d_reclen == 0 || i + dp->d_reclen > DIRBLKSIZ)
828 panic("ufsdirhash_checkblock: bad dir");
829
830 if (dp->d_ino == 0) {
831 #if 0
832 /*
833 * XXX entries with d_ino == 0 should only occur
834 * at the start of a DIRBLKSIZ block. However the
835 * ufs code is tolerant of such entries at other
836 * offsets, and fsck does not fix them.
837 */
838 if (i != 0)
839 panic("ufsdirhash_checkblock: bad dir inode");
840 #endif
841 nfree += dp->d_reclen;
842 continue;
843 }
844
845 /* Check that the entry exists (will panic if it doesn't). */
846 ufsdirhash_findslot(dh, dp->d_name, dp->d_namlen, offset + i);
847
848 nfree += dp->d_reclen - DIRSIZ(0, dp);
849 }
850 if (i != DIRBLKSIZ)
851 panic("ufsdirhash_checkblock: bad dir end");
852
853 if (dh->dh_blkfree[block] * DIRALIGN != nfree)
854 panic("ufsdirhash_checkblock: bad free count");
855
856 ffslot = BLKFREE2IDX(nfree / DIRALIGN);
857 for (i = 0; i <= DH_NFSTATS; i++)
858 if (dh->dh_firstfree[i] == block && i != ffslot)
859 panic("ufsdirhash_checkblock: bad first-free");
860 if (dh->dh_firstfree[ffslot] == -1)
861 panic("ufsdirhash_checkblock: missing first-free entry");
862 mtx_unlock(&dh->dh_mtx);
863 }
864
865 /*
866 * Hash the specified filename into a dirhash slot.
867 */
868 static int
869 ufsdirhash_hash(struct dirhash *dh, char *name, int namelen)
870 {
871 u_int32_t hash;
872
873 /*
874 * We hash the name and then some other bit of data that is
875 * invariant over the dirhash's lifetime. Otherwise names
876 * differing only in the last byte are placed close to one
877 * another in the table, which is bad for linear probing.
878 */
879 hash = fnv_32_buf(name, namelen, FNV1_32_INIT);
880 hash = fnv_32_buf(dh, sizeof(dh), hash);
881 return (hash % dh->dh_hlen);
882 }
883
884 /*
885 * Adjust the number of free bytes in the block containing `offset'
886 * by the value specified by `diff'.
887 *
888 * The caller must ensure we have exclusive access to `dh'; normally
889 * that means that dh_mtx should be held, but this is also called
890 * from ufsdirhash_build() where exclusive access can be assumed.
891 */
892 static void
893 ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff)
894 {
895 int block, i, nfidx, ofidx;
896
897 /* Update the per-block summary info. */
898 block = offset / DIRBLKSIZ;
899 KASSERT(block < dh->dh_nblk && block < dh->dh_dirblks,
900 ("dirhash bad offset"));
901 ofidx = BLKFREE2IDX(dh->dh_blkfree[block]);
902 dh->dh_blkfree[block] = (int)dh->dh_blkfree[block] + (diff / DIRALIGN);
903 nfidx = BLKFREE2IDX(dh->dh_blkfree[block]);
904
905 /* Update the `first free' list if necessary. */
906 if (ofidx != nfidx) {
907 /* If removing, scan forward for the next block. */
908 if (dh->dh_firstfree[ofidx] == block) {
909 for (i = block + 1; i < dh->dh_dirblks; i++)
910 if (BLKFREE2IDX(dh->dh_blkfree[i]) == ofidx)
911 break;
912 dh->dh_firstfree[ofidx] = (i < dh->dh_dirblks) ? i : -1;
913 }
914
915 /* Make this the new `first free' if necessary */
916 if (dh->dh_firstfree[nfidx] > block ||
917 dh->dh_firstfree[nfidx] == -1)
918 dh->dh_firstfree[nfidx] = block;
919 }
920 }
921
922 /*
923 * Find the specified name which should have the specified offset.
924 * Returns a slot number, and panics on failure.
925 *
926 * `dh' must be locked on entry and remains so on return.
927 */
928 static int
929 ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, doff_t offset)
930 {
931 int slot;
932
933 mtx_assert(&dh->dh_mtx, MA_OWNED);
934
935 /* Find the entry. */
936 KASSERT(dh->dh_hused < dh->dh_hlen, ("dirhash find full"));
937 slot = ufsdirhash_hash(dh, name, namelen);
938 while (DH_ENTRY(dh, slot) != offset &&
939 DH_ENTRY(dh, slot) != DIRHASH_EMPTY)
940 slot = WRAPINCR(slot, dh->dh_hlen);
941 if (DH_ENTRY(dh, slot) != offset)
942 panic("ufsdirhash_findslot: '%.*s' not found", namelen, name);
943
944 return (slot);
945 }
946
947 /*
948 * Remove the entry corresponding to the specified slot from the hash array.
949 *
950 * `dh' must be locked on entry and remains so on return.
951 */
952 static void
953 ufsdirhash_delslot(struct dirhash *dh, int slot)
954 {
955 int i;
956
957 mtx_assert(&dh->dh_mtx, MA_OWNED);
958
959 /* Mark the entry as deleted. */
960 DH_ENTRY(dh, slot) = DIRHASH_DEL;
961
962 /* If this is the end of a chain of DIRHASH_DEL slots, remove them. */
963 for (i = slot; DH_ENTRY(dh, i) == DIRHASH_DEL; )
964 i = WRAPINCR(i, dh->dh_hlen);
965 if (DH_ENTRY(dh, i) == DIRHASH_EMPTY) {
966 i = WRAPDECR(i, dh->dh_hlen);
967 while (DH_ENTRY(dh, i) == DIRHASH_DEL) {
968 DH_ENTRY(dh, i) = DIRHASH_EMPTY;
969 dh->dh_hused--;
970 i = WRAPDECR(i, dh->dh_hlen);
971 }
972 KASSERT(dh->dh_hused >= 0, ("ufsdirhash_delslot neg hlen"));
973 }
974 }
975
976 /*
977 * Given a directory entry and its offset, find the offset of the
978 * previous entry in the same DIRBLKSIZ-sized block. Returns an
979 * offset, or -1 if there is no previous entry in the block or some
980 * other problem occurred.
981 */
982 static doff_t
983 ufsdirhash_getprev(struct direct *dirp, doff_t offset)
984 {
985 struct direct *dp;
986 char *blkbuf;
987 doff_t blkoff, prevoff;
988 int entrypos, i;
989
990 blkoff = offset & ~(DIRBLKSIZ - 1); /* offset of start of block */
991 entrypos = offset & (DIRBLKSIZ - 1); /* entry relative to block */
992 blkbuf = (char *)dirp - entrypos;
993 prevoff = blkoff;
994
995 /* If `offset' is the start of a block, there is no previous entry. */
996 if (entrypos == 0)
997 return (-1);
998
999 /* Scan from the start of the block until we get to the entry. */
1000 for (i = 0; i < entrypos; i += dp->d_reclen) {
1001 dp = (struct direct *)(blkbuf + i);
1002 if (dp->d_reclen == 0 || i + dp->d_reclen > entrypos)
1003 return (-1); /* Corrupted directory. */
1004 prevoff = blkoff + i;
1005 }
1006 return (prevoff);
1007 }
1008
1009 /*
1010 * Try to free up `wanted' bytes by stealing memory from existing
1011 * dirhashes. Returns zero with ufsdirhash_mtx locked if successful.
1012 */
1013 static int
1014 ufsdirhash_recycle(int wanted)
1015 {
1016 struct dirhash *dh;
1017 doff_t **hash;
1018 u_int8_t *blkfree;
1019 int i, mem, narrays;
1020
1021 mtx_lock(&ufsdirhash_mtx);
1022 while (wanted + ufs_dirhashmem > ufs_dirhashmaxmem) {
1023 /* Find a dirhash, and lock it. */
1024 if ((dh = TAILQ_FIRST(&ufsdirhash_list)) == NULL) {
1025 mtx_unlock(&ufsdirhash_mtx);
1026 return (-1);
1027 }
1028 mtx_lock(&dh->dh_mtx);
1029 KASSERT(dh->dh_hash != NULL, ("dirhash: NULL hash on list"));
1030
1031 /* Decrement the score; only recycle if it becomes zero. */
1032 if (--dh->dh_score > 0) {
1033 mtx_unlock(&dh->dh_mtx);
1034 mtx_unlock(&ufsdirhash_mtx);
1035 return (-1);
1036 }
1037
1038 /* Remove it from the list and detach its memory. */
1039 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list);
1040 dh->dh_onlist = 0;
1041 hash = dh->dh_hash;
1042 dh->dh_hash = NULL;
1043 blkfree = dh->dh_blkfree;
1044 dh->dh_blkfree = NULL;
1045 narrays = dh->dh_narrays;
1046 mem = narrays * sizeof(*dh->dh_hash) +
1047 narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) +
1048 dh->dh_nblk * sizeof(*dh->dh_blkfree);
1049
1050 /* Unlock everything, free the detached memory. */
1051 mtx_unlock(&dh->dh_mtx);
1052 mtx_unlock(&ufsdirhash_mtx);
1053 for (i = 0; i < narrays; i++)
1054 uma_zfree(ufsdirhash_zone, hash[i]);
1055 FREE(hash, M_DIRHASH);
1056 FREE(blkfree, M_DIRHASH);
1057
1058 /* Account for the returned memory, and repeat if necessary. */
1059 mtx_lock(&ufsdirhash_mtx);
1060 ufs_dirhashmem -= mem;
1061 }
1062 /* Success; return with ufsdirhash_mtx locked. */
1063 return (0);
1064 }
1065
1066
1067 void
1068 ufsdirhash_init()
1069 {
1070 ufsdirhash_zone = uma_zcreate("DIRHASH", DH_NBLKOFF * sizeof(doff_t),
1071 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
1072 mtx_init(&ufsdirhash_mtx, "dirhash list", NULL, MTX_DEF);
1073 TAILQ_INIT(&ufsdirhash_list);
1074 }
1075
1076 void
1077 ufsdirhash_uninit()
1078 {
1079 KASSERT(TAILQ_EMPTY(&ufsdirhash_list), ("ufsdirhash_uninit"));
1080 uma_zdestroy(ufsdirhash_zone);
1081 mtx_destroy(&ufsdirhash_mtx);
1082 }
1083
1084 #endif /* UFS_DIRHASH */
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