1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2001, 2002 Ian Dowse. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 /* 29 * This implements a hash-based lookup scheme for UFS directories. 30 */ 31 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include "opt_ufs.h" 36 37 #ifdef UFS_DIRHASH 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/kernel.h> 42 #include <sys/lock.h> 43 #include <sys/mutex.h> 44 #include <sys/malloc.h> 45 #include <sys/fnv_hash.h> 46 #include <sys/proc.h> 47 #include <sys/bio.h> 48 #include <sys/buf.h> 49 #include <sys/vnode.h> 50 #include <sys/mount.h> 51 #include <sys/refcount.h> 52 #include <sys/sysctl.h> 53 #include <sys/sx.h> 54 #include <sys/eventhandler.h> 55 #include <sys/time.h> 56 #include <vm/uma.h> 57 58 #include <ufs/ufs/quota.h> 59 #include <ufs/ufs/inode.h> 60 #include <ufs/ufs/dir.h> 61 #include <ufs/ufs/dirhash.h> 62 #include <ufs/ufs/extattr.h> 63 #include <ufs/ufs/ufsmount.h> 64 #include <ufs/ufs/ufs_extern.h> 65 66 #define WRAPINCR(val, limit) (((val) + 1 == (limit)) ? 0 : ((val) + 1)) 67 #define WRAPDECR(val, limit) (((val) == 0) ? ((limit) - 1) : ((val) - 1)) 68 #define OFSFMT(vp) ((vp)->v_mount->mnt_maxsymlinklen <= 0) 69 #define BLKFREE2IDX(n) ((n) > DH_NFSTATS ? DH_NFSTATS : (n)) 70 71 static MALLOC_DEFINE(M_DIRHASH, "ufs_dirhash", "UFS directory hash tables"); 72 73 static int ufs_mindirhashsize = DIRBLKSIZ * 5; 74 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_minsize, CTLFLAG_RW, 75 &ufs_mindirhashsize, 76 0, "minimum directory size in bytes for which to use hashed lookup"); 77 static int ufs_dirhashmaxmem = 2 * 1024 * 1024; /* NOTE: initial value. It is 78 tuned in ufsdirhash_init() */ 79 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_maxmem, CTLFLAG_RW, &ufs_dirhashmaxmem, 80 0, "maximum allowed dirhash memory usage"); 81 static int ufs_dirhashmem; 82 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_mem, CTLFLAG_RD, &ufs_dirhashmem, 83 0, "current dirhash memory usage"); 84 static int ufs_dirhashcheck = 0; 85 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_docheck, CTLFLAG_RW, &ufs_dirhashcheck, 86 0, "enable extra sanity tests"); 87 static int ufs_dirhashlowmemcount = 0; 88 SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_lowmemcount, CTLFLAG_RD, 89 &ufs_dirhashlowmemcount, 0, "number of times low memory hook called"); 90 static int ufs_dirhashreclaimpercent = 10; 91 static int ufsdirhash_set_reclaimpercent(SYSCTL_HANDLER_ARGS); 92 SYSCTL_PROC(_vfs_ufs, OID_AUTO, dirhash_reclaimpercent, 93 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, 94 0, 0, ufsdirhash_set_reclaimpercent, "I", 95 "set percentage of dirhash cache to be removed in low VM events"); 96 97 static int ufsdirhash_hash(struct dirhash *dh, char *name, int namelen); 98 static void ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff); 99 static void ufsdirhash_delslot(struct dirhash *dh, int slot); 100 static int ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, 101 doff_t offset); 102 static doff_t ufsdirhash_getprev(struct direct *dp, doff_t offset); 103 static int ufsdirhash_recycle(int wanted); 104 static void ufsdirhash_lowmem(void); 105 static void ufsdirhash_free_locked(struct inode *ip); 106 107 static uma_zone_t ufsdirhash_zone; 108 109 #define DIRHASHLIST_LOCK() mtx_lock(&ufsdirhash_mtx) 110 #define DIRHASHLIST_UNLOCK() mtx_unlock(&ufsdirhash_mtx) 111 #define DIRHASH_BLKALLOC_WAITOK() uma_zalloc(ufsdirhash_zone, M_WAITOK) 112 #define DIRHASH_BLKFREE(ptr) uma_zfree(ufsdirhash_zone, (ptr)) 113 #define DIRHASH_ASSERT_LOCKED(dh) \ 114 sx_assert(&(dh)->dh_lock, SA_LOCKED) 115 116 /* Dirhash list; recently-used entries are near the tail. */ 117 static TAILQ_HEAD(, dirhash) ufsdirhash_list; 118 119 /* Protects: ufsdirhash_list, `dh_list' field, ufs_dirhashmem. */ 120 static struct mtx ufsdirhash_mtx; 121 122 /* 123 * Locking: 124 * 125 * The relationship between inode and dirhash is protected either by an 126 * exclusive vnode lock or the vnode interlock where a shared vnode lock 127 * may be used. The dirhash_mtx is acquired after the dirhash lock. To 128 * handle teardown races, code wishing to lock the dirhash for an inode 129 * when using a shared vnode lock must obtain a private reference on the 130 * dirhash while holding the vnode interlock. They can drop it once they 131 * have obtained the dirhash lock and verified that the dirhash wasn't 132 * recycled while they waited for the dirhash lock. 133 * 134 * ufsdirhash_build() acquires a shared lock on the dirhash when it is 135 * successful. This lock is released after a call to ufsdirhash_lookup(). 136 * 137 * Functions requiring exclusive access use ufsdirhash_acquire() which may 138 * free a dirhash structure that was recycled by ufsdirhash_recycle(). 139 * 140 * The dirhash lock may be held across io operations. 141 * 142 * WITNESS reports a lock order reversal between the "bufwait" lock 143 * and the "dirhash" lock. However, this specific reversal will not 144 * cause a deadlock. To get a deadlock, one would have to lock a 145 * buffer followed by the dirhash while a second thread locked a 146 * buffer while holding the dirhash lock. The second order can happen 147 * under a shared or exclusive vnode lock for the associated directory 148 * in lookup(). The first order, however, can only happen under an 149 * exclusive vnode lock (e.g. unlink(), rename(), etc.). Thus, for 150 * a thread to be doing a "bufwait" -> "dirhash" order, it has to hold 151 * an exclusive vnode lock. That exclusive vnode lock will prevent 152 * any other threads from doing a "dirhash" -> "bufwait" order. 153 */ 154 155 static void 156 ufsdirhash_hold(struct dirhash *dh) 157 { 158 159 refcount_acquire(&dh->dh_refcount); 160 } 161 162 static void 163 ufsdirhash_drop(struct dirhash *dh) 164 { 165 166 if (refcount_release(&dh->dh_refcount)) { 167 sx_destroy(&dh->dh_lock); 168 free(dh, M_DIRHASH); 169 } 170 } 171 172 /* 173 * Release the lock on a dirhash. 174 */ 175 static void 176 ufsdirhash_release(struct dirhash *dh) 177 { 178 179 sx_unlock(&dh->dh_lock); 180 } 181 182 /* 183 * Either acquire an existing hash locked shared or create a new hash and 184 * return it exclusively locked. May return NULL if the allocation fails. 185 * 186 * The vnode interlock is used to protect the i_dirhash pointer from 187 * simultaneous access while only a shared vnode lock is held. 188 */ 189 static struct dirhash * 190 ufsdirhash_create(struct inode *ip) 191 { 192 struct dirhash *ndh; 193 struct dirhash *dh; 194 struct vnode *vp; 195 bool excl; 196 197 ndh = dh = NULL; 198 vp = ip->i_vnode; 199 excl = false; 200 for (;;) { 201 /* Racy check for i_dirhash to prefetch a dirhash structure. */ 202 if (ip->i_dirhash == NULL && ndh == NULL) { 203 ndh = malloc(sizeof *dh, M_DIRHASH, 204 M_NOWAIT | M_ZERO); 205 if (ndh == NULL) 206 return (NULL); 207 refcount_init(&ndh->dh_refcount, 1); 208 209 /* 210 * The DUPOK is to prevent warnings from the 211 * sx_slock() a few lines down which is safe 212 * since the duplicate lock in that case is 213 * the one for this dirhash we are creating 214 * now which has no external references until 215 * after this function returns. 216 */ 217 sx_init_flags(&ndh->dh_lock, "dirhash", SX_DUPOK); 218 sx_xlock(&ndh->dh_lock); 219 } 220 /* 221 * Check i_dirhash. If it's NULL just try to use a 222 * preallocated structure. If none exists loop and try again. 223 */ 224 VI_LOCK(vp); 225 dh = ip->i_dirhash; 226 if (dh == NULL) { 227 ip->i_dirhash = ndh; 228 VI_UNLOCK(vp); 229 if (ndh == NULL) 230 continue; 231 return (ndh); 232 } 233 ufsdirhash_hold(dh); 234 VI_UNLOCK(vp); 235 236 /* Acquire a lock on existing hashes. */ 237 if (excl) 238 sx_xlock(&dh->dh_lock); 239 else 240 sx_slock(&dh->dh_lock); 241 242 /* The hash could've been recycled while we were waiting. */ 243 VI_LOCK(vp); 244 if (ip->i_dirhash != dh) { 245 VI_UNLOCK(vp); 246 ufsdirhash_release(dh); 247 ufsdirhash_drop(dh); 248 continue; 249 } 250 VI_UNLOCK(vp); 251 ufsdirhash_drop(dh); 252 253 /* If the hash is still valid we've succeeded. */ 254 if (dh->dh_hash != NULL) 255 break; 256 /* 257 * If the hash is NULL it has been recycled. Try to upgrade 258 * so we can recreate it. If we fail the upgrade, drop our 259 * lock and try again. 260 */ 261 if (excl || sx_try_upgrade(&dh->dh_lock)) 262 break; 263 sx_sunlock(&dh->dh_lock); 264 excl = true; 265 } 266 /* Free the preallocated structure if it was not necessary. */ 267 if (ndh) { 268 ufsdirhash_release(ndh); 269 ufsdirhash_drop(ndh); 270 } 271 return (dh); 272 } 273 274 /* 275 * Acquire an exclusive lock on an existing hash. Requires an exclusive 276 * vnode lock to protect the i_dirhash pointer. hashes that have been 277 * recycled are reclaimed here and NULL is returned. 278 */ 279 static struct dirhash * 280 ufsdirhash_acquire(struct inode *ip) 281 { 282 struct dirhash *dh; 283 284 ASSERT_VOP_ELOCKED(ip->i_vnode, __FUNCTION__); 285 286 dh = ip->i_dirhash; 287 if (dh == NULL) 288 return (NULL); 289 sx_xlock(&dh->dh_lock); 290 if (dh->dh_hash != NULL) 291 return (dh); 292 ufsdirhash_free_locked(ip); 293 return (NULL); 294 } 295 296 /* 297 * Acquire exclusively and free the hash pointed to by ip. Works with a 298 * shared or exclusive vnode lock. 299 */ 300 void 301 ufsdirhash_free(struct inode *ip) 302 { 303 struct dirhash *dh; 304 struct vnode *vp; 305 306 vp = ip->i_vnode; 307 for (;;) { 308 /* Grab a reference on this inode's dirhash if it has one. */ 309 VI_LOCK(vp); 310 dh = ip->i_dirhash; 311 if (dh == NULL) { 312 VI_UNLOCK(vp); 313 return; 314 } 315 ufsdirhash_hold(dh); 316 VI_UNLOCK(vp); 317 318 /* Exclusively lock the dirhash. */ 319 sx_xlock(&dh->dh_lock); 320 321 /* If this dirhash still belongs to this inode, then free it. */ 322 VI_LOCK(vp); 323 if (ip->i_dirhash == dh) { 324 VI_UNLOCK(vp); 325 ufsdirhash_drop(dh); 326 break; 327 } 328 VI_UNLOCK(vp); 329 330 /* 331 * This inode's dirhash has changed while we were 332 * waiting for the dirhash lock, so try again. 333 */ 334 ufsdirhash_release(dh); 335 ufsdirhash_drop(dh); 336 } 337 ufsdirhash_free_locked(ip); 338 } 339 340 /* 341 * Attempt to build up a hash table for the directory contents in 342 * inode 'ip'. Returns 0 on success, or -1 of the operation failed. 343 */ 344 int 345 ufsdirhash_build(struct inode *ip) 346 { 347 struct dirhash *dh; 348 struct buf *bp = NULL; 349 struct direct *ep; 350 struct vnode *vp; 351 doff_t bmask, pos; 352 u_int dirblocks, i, narrays, nblocks, nslots; 353 int j, memreqd, slot; 354 355 /* Take care of a decreased sysctl value. */ 356 while (ufs_dirhashmem > ufs_dirhashmaxmem) { 357 if (ufsdirhash_recycle(0) != 0) 358 return (-1); 359 /* Recycled enough memory, so unlock the list. */ 360 DIRHASHLIST_UNLOCK(); 361 } 362 363 /* Check if we can/should use dirhash. */ 364 if (ip->i_size < ufs_mindirhashsize || OFSFMT(ip->i_vnode) || 365 ip->i_effnlink == 0) { 366 if (ip->i_dirhash) 367 ufsdirhash_free(ip); 368 return (-1); 369 } 370 dh = ufsdirhash_create(ip); 371 if (dh == NULL) 372 return (-1); 373 if (dh->dh_hash != NULL) 374 return (0); 375 376 vp = ip->i_vnode; 377 /* Allocate 50% more entries than this dir size could ever need. */ 378 KASSERT(ip->i_size >= DIRBLKSIZ, ("ufsdirhash_build size")); 379 nslots = ip->i_size / DIRECTSIZ(1); 380 nslots = (nslots * 3 + 1) / 2; 381 narrays = howmany(nslots, DH_NBLKOFF); 382 nslots = narrays * DH_NBLKOFF; 383 dirblocks = howmany(ip->i_size, DIRBLKSIZ); 384 nblocks = (dirblocks * 3 + 1) / 2; 385 memreqd = sizeof(*dh) + narrays * sizeof(*dh->dh_hash) + 386 narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) + 387 nblocks * sizeof(*dh->dh_blkfree); 388 DIRHASHLIST_LOCK(); 389 if (memreqd + ufs_dirhashmem > ufs_dirhashmaxmem) { 390 DIRHASHLIST_UNLOCK(); 391 if (memreqd > ufs_dirhashmaxmem / 2) 392 goto fail; 393 /* Try to free some space. */ 394 if (ufsdirhash_recycle(memreqd) != 0) 395 goto fail; 396 /* Enough was freed, and list has been locked. */ 397 } 398 ufs_dirhashmem += memreqd; 399 DIRHASHLIST_UNLOCK(); 400 401 /* Initialise the hash table and block statistics. */ 402 dh->dh_memreq = memreqd; 403 dh->dh_narrays = narrays; 404 dh->dh_hlen = nslots; 405 dh->dh_nblk = nblocks; 406 dh->dh_dirblks = dirblocks; 407 for (i = 0; i < DH_NFSTATS; i++) 408 dh->dh_firstfree[i] = -1; 409 dh->dh_firstfree[DH_NFSTATS] = 0; 410 dh->dh_hused = 0; 411 dh->dh_seqoff = -1; 412 dh->dh_score = DH_SCOREINIT; 413 dh->dh_lastused = time_second; 414 415 /* 416 * Use non-blocking mallocs so that we will revert to a linear 417 * lookup on failure rather than potentially blocking forever. 418 */ 419 dh->dh_hash = malloc(narrays * sizeof(dh->dh_hash[0]), 420 M_DIRHASH, M_NOWAIT | M_ZERO); 421 if (dh->dh_hash == NULL) 422 goto fail; 423 dh->dh_blkfree = malloc(nblocks * sizeof(dh->dh_blkfree[0]), 424 M_DIRHASH, M_NOWAIT); 425 if (dh->dh_blkfree == NULL) 426 goto fail; 427 for (i = 0; i < narrays; i++) { 428 if ((dh->dh_hash[i] = DIRHASH_BLKALLOC_WAITOK()) == NULL) 429 goto fail; 430 for (j = 0; j < DH_NBLKOFF; j++) 431 dh->dh_hash[i][j] = DIRHASH_EMPTY; 432 } 433 for (i = 0; i < dirblocks; i++) 434 dh->dh_blkfree[i] = DIRBLKSIZ / DIRALIGN; 435 bmask = vp->v_mount->mnt_stat.f_iosize - 1; 436 pos = 0; 437 while (pos < ip->i_size) { 438 /* If necessary, get the next directory block. */ 439 if ((pos & bmask) == 0) { 440 if (bp != NULL) 441 brelse(bp); 442 if (UFS_BLKATOFF(vp, (off_t)pos, NULL, &bp) != 0) 443 goto fail; 444 } 445 446 /* Add this entry to the hash. */ 447 ep = (struct direct *)((char *)bp->b_data + (pos & bmask)); 448 if (ep->d_reclen == 0 || ep->d_reclen > 449 DIRBLKSIZ - (pos & (DIRBLKSIZ - 1))) { 450 /* Corrupted directory. */ 451 brelse(bp); 452 goto fail; 453 } 454 if (ep->d_ino != 0) { 455 /* Add the entry (simplified ufsdirhash_add). */ 456 slot = ufsdirhash_hash(dh, ep->d_name, ep->d_namlen); 457 while (DH_ENTRY(dh, slot) != DIRHASH_EMPTY) 458 slot = WRAPINCR(slot, dh->dh_hlen); 459 dh->dh_hused++; 460 DH_ENTRY(dh, slot) = pos; 461 ufsdirhash_adjfree(dh, pos, -DIRSIZ(0, ep)); 462 } 463 pos += ep->d_reclen; 464 } 465 466 if (bp != NULL) 467 brelse(bp); 468 DIRHASHLIST_LOCK(); 469 TAILQ_INSERT_TAIL(&ufsdirhash_list, dh, dh_list); 470 dh->dh_onlist = 1; 471 DIRHASHLIST_UNLOCK(); 472 sx_downgrade(&dh->dh_lock); 473 return (0); 474 475 fail: 476 ufsdirhash_free_locked(ip); 477 return (-1); 478 } 479 480 /* 481 * Free any hash table associated with inode 'ip'. 482 */ 483 static void 484 ufsdirhash_free_locked(struct inode *ip) 485 { 486 struct dirhash *dh; 487 struct vnode *vp; 488 int i; 489 490 DIRHASH_ASSERT_LOCKED(ip->i_dirhash); 491 492 /* 493 * Clear the pointer in the inode to prevent new threads from 494 * finding the dead structure. 495 */ 496 vp = ip->i_vnode; 497 VI_LOCK(vp); 498 dh = ip->i_dirhash; 499 ip->i_dirhash = NULL; 500 VI_UNLOCK(vp); 501 502 /* 503 * Remove the hash from the list since we are going to free its 504 * memory. 505 */ 506 DIRHASHLIST_LOCK(); 507 if (dh->dh_onlist) 508 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 509 ufs_dirhashmem -= dh->dh_memreq; 510 DIRHASHLIST_UNLOCK(); 511 512 /* 513 * At this point, any waiters for the lock should hold their 514 * own reference on the dirhash structure. They will drop 515 * that reference once they grab the vnode interlock and see 516 * that ip->i_dirhash is NULL. 517 */ 518 sx_xunlock(&dh->dh_lock); 519 520 /* 521 * Handle partially recycled as well as fully constructed hashes. 522 */ 523 if (dh->dh_hash != NULL) { 524 for (i = 0; i < dh->dh_narrays; i++) 525 if (dh->dh_hash[i] != NULL) 526 DIRHASH_BLKFREE(dh->dh_hash[i]); 527 free(dh->dh_hash, M_DIRHASH); 528 if (dh->dh_blkfree != NULL) 529 free(dh->dh_blkfree, M_DIRHASH); 530 } 531 532 /* 533 * Drop the inode's reference to the data structure. 534 */ 535 ufsdirhash_drop(dh); 536 } 537 538 /* 539 * Find the offset of the specified name within the given inode. 540 * Returns 0 on success, ENOENT if the entry does not exist, or 541 * EJUSTRETURN if the caller should revert to a linear search. 542 * 543 * If successful, the directory offset is stored in *offp, and a 544 * pointer to a struct buf containing the entry is stored in *bpp. If 545 * prevoffp is non-NULL, the offset of the previous entry within 546 * the DIRBLKSIZ-sized block is stored in *prevoffp (if the entry 547 * is the first in a block, the start of the block is used). 548 * 549 * Must be called with the hash locked. Returns with the hash unlocked. 550 */ 551 int 552 ufsdirhash_lookup(struct inode *ip, char *name, int namelen, doff_t *offp, 553 struct buf **bpp, doff_t *prevoffp) 554 { 555 struct dirhash *dh, *dh_next; 556 struct direct *dp; 557 struct vnode *vp; 558 struct buf *bp; 559 doff_t blkoff, bmask, offset, prevoff, seqoff; 560 int i, slot; 561 int error; 562 563 dh = ip->i_dirhash; 564 KASSERT(dh != NULL && dh->dh_hash != NULL, 565 ("ufsdirhash_lookup: Invalid dirhash %p\n", dh)); 566 DIRHASH_ASSERT_LOCKED(dh); 567 /* 568 * Move this dirhash towards the end of the list if it has a 569 * score higher than the next entry, and acquire the dh_lock. 570 */ 571 DIRHASHLIST_LOCK(); 572 if (TAILQ_NEXT(dh, dh_list) != NULL) { 573 /* 574 * If the new score will be greater than that of the next 575 * entry, then move this entry past it. With both mutexes 576 * held, dh_next won't go away, but its dh_score could 577 * change; that's not important since it is just a hint. 578 */ 579 if ((dh_next = TAILQ_NEXT(dh, dh_list)) != NULL && 580 dh->dh_score >= dh_next->dh_score) { 581 KASSERT(dh->dh_onlist, ("dirhash: not on list")); 582 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 583 TAILQ_INSERT_AFTER(&ufsdirhash_list, dh_next, dh, 584 dh_list); 585 } 586 } 587 /* Update the score. */ 588 if (dh->dh_score < DH_SCOREMAX) 589 dh->dh_score++; 590 591 /* Update last used time. */ 592 dh->dh_lastused = time_second; 593 DIRHASHLIST_UNLOCK(); 594 595 vp = ip->i_vnode; 596 bmask = vp->v_mount->mnt_stat.f_iosize - 1; 597 blkoff = -1; 598 bp = NULL; 599 seqoff = dh->dh_seqoff; 600 restart: 601 slot = ufsdirhash_hash(dh, name, namelen); 602 603 if (seqoff != -1) { 604 /* 605 * Sequential access optimisation. seqoff contains the 606 * offset of the directory entry immediately following 607 * the last entry that was looked up. Check if this offset 608 * appears in the hash chain for the name we are looking for. 609 */ 610 for (i = slot; (offset = DH_ENTRY(dh, i)) != DIRHASH_EMPTY; 611 i = WRAPINCR(i, dh->dh_hlen)) 612 if (offset == seqoff) 613 break; 614 if (offset == seqoff) { 615 /* 616 * We found an entry with the expected offset. This 617 * is probably the entry we want, but if not, the 618 * code below will retry. 619 */ 620 slot = i; 621 } else 622 seqoff = -1; 623 } 624 625 for (; (offset = DH_ENTRY(dh, slot)) != DIRHASH_EMPTY; 626 slot = WRAPINCR(slot, dh->dh_hlen)) { 627 if (offset == DIRHASH_DEL) 628 continue; 629 if (offset < 0 || offset >= ip->i_size) 630 panic("ufsdirhash_lookup: bad offset in hash array"); 631 if ((offset & ~bmask) != blkoff) { 632 if (bp != NULL) 633 brelse(bp); 634 blkoff = offset & ~bmask; 635 if (UFS_BLKATOFF(vp, (off_t)blkoff, NULL, &bp) != 0) { 636 error = EJUSTRETURN; 637 goto fail; 638 } 639 } 640 KASSERT(bp != NULL, ("no buffer allocated")); 641 dp = (struct direct *)(bp->b_data + (offset & bmask)); 642 if (dp->d_reclen == 0 || dp->d_reclen > 643 DIRBLKSIZ - (offset & (DIRBLKSIZ - 1))) { 644 /* Corrupted directory. */ 645 error = EJUSTRETURN; 646 goto fail; 647 } 648 if (dp->d_namlen == namelen && 649 bcmp(dp->d_name, name, namelen) == 0) { 650 /* Found. Get the prev offset if needed. */ 651 if (prevoffp != NULL) { 652 if (offset & (DIRBLKSIZ - 1)) { 653 prevoff = ufsdirhash_getprev(dp, 654 offset); 655 if (prevoff == -1) { 656 error = EJUSTRETURN; 657 goto fail; 658 } 659 } else 660 prevoff = offset; 661 *prevoffp = prevoff; 662 } 663 664 /* Update offset. */ 665 dh->dh_seqoff = offset + DIRSIZ(0, dp); 666 *bpp = bp; 667 *offp = offset; 668 ufsdirhash_release(dh); 669 return (0); 670 } 671 672 /* 673 * When the name doesn't match in the sequential 674 * optimization case, go back and search normally. 675 */ 676 if (seqoff != -1) { 677 seqoff = -1; 678 goto restart; 679 } 680 } 681 error = ENOENT; 682 fail: 683 ufsdirhash_release(dh); 684 if (bp != NULL) 685 brelse(bp); 686 return (error); 687 } 688 689 /* 690 * Find a directory block with room for 'slotneeded' bytes. Returns 691 * the offset of the directory entry that begins the free space. 692 * This will either be the offset of an existing entry that has free 693 * space at the end, or the offset of an entry with d_ino == 0 at 694 * the start of a DIRBLKSIZ block. 695 * 696 * To use the space, the caller may need to compact existing entries in 697 * the directory. The total number of bytes in all of the entries involved 698 * in the compaction is stored in *slotsize. In other words, all of 699 * the entries that must be compacted are exactly contained in the 700 * region beginning at the returned offset and spanning *slotsize bytes. 701 * 702 * Returns -1 if no space was found, indicating that the directory 703 * must be extended. 704 */ 705 doff_t 706 ufsdirhash_findfree(struct inode *ip, int slotneeded, int *slotsize) 707 { 708 struct direct *dp; 709 struct dirhash *dh; 710 struct buf *bp; 711 doff_t pos, slotstart; 712 int dirblock, error, freebytes, i; 713 714 dh = ip->i_dirhash; 715 KASSERT(dh != NULL && dh->dh_hash != NULL, 716 ("ufsdirhash_findfree: Invalid dirhash %p\n", dh)); 717 DIRHASH_ASSERT_LOCKED(dh); 718 719 /* Find a directory block with the desired free space. */ 720 dirblock = -1; 721 for (i = howmany(slotneeded, DIRALIGN); i <= DH_NFSTATS; i++) 722 if ((dirblock = dh->dh_firstfree[i]) != -1) 723 break; 724 if (dirblock == -1) 725 return (-1); 726 727 KASSERT(dirblock < dh->dh_nblk && 728 dh->dh_blkfree[dirblock] >= howmany(slotneeded, DIRALIGN), 729 ("ufsdirhash_findfree: bad stats")); 730 pos = dirblock * DIRBLKSIZ; 731 error = UFS_BLKATOFF(ip->i_vnode, (off_t)pos, (char **)&dp, &bp); 732 if (error) 733 return (-1); 734 735 /* Find the first entry with free space. */ 736 for (i = 0; i < DIRBLKSIZ; ) { 737 if (dp->d_reclen == 0) { 738 brelse(bp); 739 return (-1); 740 } 741 if (dp->d_ino == 0 || dp->d_reclen > DIRSIZ(0, dp)) 742 break; 743 i += dp->d_reclen; 744 dp = (struct direct *)((char *)dp + dp->d_reclen); 745 } 746 if (i > DIRBLKSIZ) { 747 brelse(bp); 748 return (-1); 749 } 750 slotstart = pos + i; 751 752 /* Find the range of entries needed to get enough space */ 753 freebytes = 0; 754 while (i < DIRBLKSIZ && freebytes < slotneeded) { 755 freebytes += dp->d_reclen; 756 if (dp->d_ino != 0) 757 freebytes -= DIRSIZ(0, dp); 758 if (dp->d_reclen == 0) { 759 brelse(bp); 760 return (-1); 761 } 762 i += dp->d_reclen; 763 dp = (struct direct *)((char *)dp + dp->d_reclen); 764 } 765 if (i > DIRBLKSIZ) { 766 brelse(bp); 767 return (-1); 768 } 769 if (freebytes < slotneeded) 770 panic("ufsdirhash_findfree: free mismatch"); 771 brelse(bp); 772 *slotsize = pos + i - slotstart; 773 return (slotstart); 774 } 775 776 /* 777 * Return the start of the unused space at the end of a directory, or 778 * -1 if there are no trailing unused blocks. 779 */ 780 doff_t 781 ufsdirhash_enduseful(struct inode *ip) 782 { 783 784 struct dirhash *dh; 785 int i; 786 787 dh = ip->i_dirhash; 788 DIRHASH_ASSERT_LOCKED(dh); 789 KASSERT(dh != NULL && dh->dh_hash != NULL, 790 ("ufsdirhash_enduseful: Invalid dirhash %p\n", dh)); 791 792 if (dh->dh_blkfree[dh->dh_dirblks - 1] != DIRBLKSIZ / DIRALIGN) 793 return (-1); 794 795 for (i = dh->dh_dirblks - 1; i >= 0; i--) 796 if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN) 797 break; 798 799 return ((doff_t)(i + 1) * DIRBLKSIZ); 800 } 801 802 /* 803 * Insert information into the hash about a new directory entry. dirp 804 * points to a struct direct containing the entry, and offset specifies 805 * the offset of this entry. 806 */ 807 void 808 ufsdirhash_add(struct inode *ip, struct direct *dirp, doff_t offset) 809 { 810 struct dirhash *dh; 811 int slot; 812 813 if ((dh = ufsdirhash_acquire(ip)) == NULL) 814 return; 815 816 KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ, 817 ("ufsdirhash_add: bad offset")); 818 /* 819 * Normal hash usage is < 66%. If the usage gets too high then 820 * remove the hash entirely and let it be rebuilt later. 821 */ 822 if (dh->dh_hused >= (dh->dh_hlen * 3) / 4) { 823 ufsdirhash_free_locked(ip); 824 return; 825 } 826 827 /* Find a free hash slot (empty or deleted), and add the entry. */ 828 slot = ufsdirhash_hash(dh, dirp->d_name, dirp->d_namlen); 829 while (DH_ENTRY(dh, slot) >= 0) 830 slot = WRAPINCR(slot, dh->dh_hlen); 831 if (DH_ENTRY(dh, slot) == DIRHASH_EMPTY) 832 dh->dh_hused++; 833 DH_ENTRY(dh, slot) = offset; 834 835 /* Update last used time. */ 836 dh->dh_lastused = time_second; 837 838 /* Update the per-block summary info. */ 839 ufsdirhash_adjfree(dh, offset, -DIRSIZ(0, dirp)); 840 ufsdirhash_release(dh); 841 } 842 843 /* 844 * Remove the specified directory entry from the hash. The entry to remove 845 * is defined by the name in `dirp', which must exist at the specified 846 * `offset' within the directory. 847 */ 848 void 849 ufsdirhash_remove(struct inode *ip, struct direct *dirp, doff_t offset) 850 { 851 struct dirhash *dh; 852 int slot; 853 854 if ((dh = ufsdirhash_acquire(ip)) == NULL) 855 return; 856 857 KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ, 858 ("ufsdirhash_remove: bad offset")); 859 /* Find the entry */ 860 slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, offset); 861 862 /* Remove the hash entry. */ 863 ufsdirhash_delslot(dh, slot); 864 865 /* Update the per-block summary info. */ 866 ufsdirhash_adjfree(dh, offset, DIRSIZ(0, dirp)); 867 ufsdirhash_release(dh); 868 } 869 870 /* 871 * Change the offset associated with a directory entry in the hash. Used 872 * when compacting directory blocks. 873 */ 874 void 875 ufsdirhash_move(struct inode *ip, struct direct *dirp, doff_t oldoff, 876 doff_t newoff) 877 { 878 struct dirhash *dh; 879 int slot; 880 881 if ((dh = ufsdirhash_acquire(ip)) == NULL) 882 return; 883 884 KASSERT(oldoff < dh->dh_dirblks * DIRBLKSIZ && 885 newoff < dh->dh_dirblks * DIRBLKSIZ, 886 ("ufsdirhash_move: bad offset")); 887 /* Find the entry, and update the offset. */ 888 slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, oldoff); 889 DH_ENTRY(dh, slot) = newoff; 890 ufsdirhash_release(dh); 891 } 892 893 /* 894 * Inform dirhash that the directory has grown by one block that 895 * begins at offset (i.e. the new length is offset + DIRBLKSIZ). 896 */ 897 void 898 ufsdirhash_newblk(struct inode *ip, doff_t offset) 899 { 900 struct dirhash *dh; 901 int block; 902 903 if ((dh = ufsdirhash_acquire(ip)) == NULL) 904 return; 905 906 KASSERT(offset == dh->dh_dirblks * DIRBLKSIZ, 907 ("ufsdirhash_newblk: bad offset")); 908 block = offset / DIRBLKSIZ; 909 if (block >= dh->dh_nblk) { 910 /* Out of space; must rebuild. */ 911 ufsdirhash_free_locked(ip); 912 return; 913 } 914 dh->dh_dirblks = block + 1; 915 916 /* Account for the new free block. */ 917 dh->dh_blkfree[block] = DIRBLKSIZ / DIRALIGN; 918 if (dh->dh_firstfree[DH_NFSTATS] == -1) 919 dh->dh_firstfree[DH_NFSTATS] = block; 920 ufsdirhash_release(dh); 921 } 922 923 /* 924 * Inform dirhash that the directory is being truncated. 925 */ 926 void 927 ufsdirhash_dirtrunc(struct inode *ip, doff_t offset) 928 { 929 struct dirhash *dh; 930 int block, i; 931 932 if ((dh = ufsdirhash_acquire(ip)) == NULL) 933 return; 934 935 KASSERT(offset <= dh->dh_dirblks * DIRBLKSIZ, 936 ("ufsdirhash_dirtrunc: bad offset")); 937 block = howmany(offset, DIRBLKSIZ); 938 /* 939 * If the directory shrinks to less than 1/8 of dh_nblk blocks 940 * (about 20% of its original size due to the 50% extra added in 941 * ufsdirhash_build) then free it, and let the caller rebuild 942 * if necessary. 943 */ 944 if (block < dh->dh_nblk / 8 && dh->dh_narrays > 1) { 945 ufsdirhash_free_locked(ip); 946 return; 947 } 948 949 /* 950 * Remove any `first free' information pertaining to the 951 * truncated blocks. All blocks we're removing should be 952 * completely unused. 953 */ 954 if (dh->dh_firstfree[DH_NFSTATS] >= block) 955 dh->dh_firstfree[DH_NFSTATS] = -1; 956 for (i = block; i < dh->dh_dirblks; i++) 957 if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN) 958 panic("ufsdirhash_dirtrunc: blocks in use"); 959 for (i = 0; i < DH_NFSTATS; i++) 960 if (dh->dh_firstfree[i] >= block) 961 panic("ufsdirhash_dirtrunc: first free corrupt"); 962 dh->dh_dirblks = block; 963 ufsdirhash_release(dh); 964 } 965 966 /* 967 * Debugging function to check that the dirhash information about 968 * a directory block matches its actual contents. Panics if a mismatch 969 * is detected. 970 * 971 * On entry, `buf' should point to the start of an in-core 972 * DIRBLKSIZ-sized directory block, and `offset' should contain the 973 * offset from the start of the directory of that block. 974 */ 975 void 976 ufsdirhash_checkblock(struct inode *ip, char *buf, doff_t offset) 977 { 978 struct dirhash *dh; 979 struct direct *dp; 980 int block, ffslot, i, nfree; 981 982 if (!ufs_dirhashcheck) 983 return; 984 if ((dh = ufsdirhash_acquire(ip)) == NULL) 985 return; 986 987 block = offset / DIRBLKSIZ; 988 if ((offset & (DIRBLKSIZ - 1)) != 0 || block >= dh->dh_dirblks) 989 panic("ufsdirhash_checkblock: bad offset"); 990 991 nfree = 0; 992 for (i = 0; i < DIRBLKSIZ; i += dp->d_reclen) { 993 dp = (struct direct *)(buf + i); 994 if (dp->d_reclen == 0 || i + dp->d_reclen > DIRBLKSIZ) 995 panic("ufsdirhash_checkblock: bad dir"); 996 997 if (dp->d_ino == 0) { 998 #if 0 999 /* 1000 * XXX entries with d_ino == 0 should only occur 1001 * at the start of a DIRBLKSIZ block. However the 1002 * ufs code is tolerant of such entries at other 1003 * offsets, and fsck does not fix them. 1004 */ 1005 if (i != 0) 1006 panic("ufsdirhash_checkblock: bad dir inode"); 1007 #endif 1008 nfree += dp->d_reclen; 1009 continue; 1010 } 1011 1012 /* Check that the entry exists (will panic if it doesn't). */ 1013 ufsdirhash_findslot(dh, dp->d_name, dp->d_namlen, offset + i); 1014 1015 nfree += dp->d_reclen - DIRSIZ(0, dp); 1016 } 1017 if (i != DIRBLKSIZ) 1018 panic("ufsdirhash_checkblock: bad dir end"); 1019 1020 if (dh->dh_blkfree[block] * DIRALIGN != nfree) 1021 panic("ufsdirhash_checkblock: bad free count"); 1022 1023 ffslot = BLKFREE2IDX(nfree / DIRALIGN); 1024 for (i = 0; i <= DH_NFSTATS; i++) 1025 if (dh->dh_firstfree[i] == block && i != ffslot) 1026 panic("ufsdirhash_checkblock: bad first-free"); 1027 if (dh->dh_firstfree[ffslot] == -1) 1028 panic("ufsdirhash_checkblock: missing first-free entry"); 1029 ufsdirhash_release(dh); 1030 } 1031 1032 /* 1033 * Hash the specified filename into a dirhash slot. 1034 */ 1035 static int 1036 ufsdirhash_hash(struct dirhash *dh, char *name, int namelen) 1037 { 1038 u_int32_t hash; 1039 1040 /* 1041 * We hash the name and then some other bit of data that is 1042 * invariant over the dirhash's lifetime. Otherwise names 1043 * differing only in the last byte are placed close to one 1044 * another in the table, which is bad for linear probing. 1045 */ 1046 hash = fnv_32_buf(name, namelen, FNV1_32_INIT); 1047 hash = fnv_32_buf(&dh, sizeof(dh), hash); 1048 return (hash % dh->dh_hlen); 1049 } 1050 1051 /* 1052 * Adjust the number of free bytes in the block containing `offset' 1053 * by the value specified by `diff'. 1054 * 1055 * The caller must ensure we have exclusive access to `dh'; normally 1056 * that means that dh_lock should be held, but this is also called 1057 * from ufsdirhash_build() where exclusive access can be assumed. 1058 */ 1059 static void 1060 ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff) 1061 { 1062 int block, i, nfidx, ofidx; 1063 1064 /* Update the per-block summary info. */ 1065 block = offset / DIRBLKSIZ; 1066 KASSERT(block < dh->dh_nblk && block < dh->dh_dirblks, 1067 ("dirhash bad offset")); 1068 ofidx = BLKFREE2IDX(dh->dh_blkfree[block]); 1069 dh->dh_blkfree[block] = (int)dh->dh_blkfree[block] + (diff / DIRALIGN); 1070 nfidx = BLKFREE2IDX(dh->dh_blkfree[block]); 1071 1072 /* Update the `first free' list if necessary. */ 1073 if (ofidx != nfidx) { 1074 /* If removing, scan forward for the next block. */ 1075 if (dh->dh_firstfree[ofidx] == block) { 1076 for (i = block + 1; i < dh->dh_dirblks; i++) 1077 if (BLKFREE2IDX(dh->dh_blkfree[i]) == ofidx) 1078 break; 1079 dh->dh_firstfree[ofidx] = (i < dh->dh_dirblks) ? i : -1; 1080 } 1081 1082 /* Make this the new `first free' if necessary */ 1083 if (dh->dh_firstfree[nfidx] > block || 1084 dh->dh_firstfree[nfidx] == -1) 1085 dh->dh_firstfree[nfidx] = block; 1086 } 1087 } 1088 1089 /* 1090 * Find the specified name which should have the specified offset. 1091 * Returns a slot number, and panics on failure. 1092 * 1093 * `dh' must be locked on entry and remains so on return. 1094 */ 1095 static int 1096 ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, doff_t offset) 1097 { 1098 int slot; 1099 1100 DIRHASH_ASSERT_LOCKED(dh); 1101 1102 /* Find the entry. */ 1103 KASSERT(dh->dh_hused < dh->dh_hlen, ("dirhash find full")); 1104 slot = ufsdirhash_hash(dh, name, namelen); 1105 while (DH_ENTRY(dh, slot) != offset && 1106 DH_ENTRY(dh, slot) != DIRHASH_EMPTY) 1107 slot = WRAPINCR(slot, dh->dh_hlen); 1108 if (DH_ENTRY(dh, slot) != offset) 1109 panic("ufsdirhash_findslot: '%.*s' not found", namelen, name); 1110 1111 return (slot); 1112 } 1113 1114 /* 1115 * Remove the entry corresponding to the specified slot from the hash array. 1116 * 1117 * `dh' must be locked on entry and remains so on return. 1118 */ 1119 static void 1120 ufsdirhash_delslot(struct dirhash *dh, int slot) 1121 { 1122 int i; 1123 1124 DIRHASH_ASSERT_LOCKED(dh); 1125 1126 /* Mark the entry as deleted. */ 1127 DH_ENTRY(dh, slot) = DIRHASH_DEL; 1128 1129 /* If this is the end of a chain of DIRHASH_DEL slots, remove them. */ 1130 for (i = slot; DH_ENTRY(dh, i) == DIRHASH_DEL; ) 1131 i = WRAPINCR(i, dh->dh_hlen); 1132 if (DH_ENTRY(dh, i) == DIRHASH_EMPTY) { 1133 i = WRAPDECR(i, dh->dh_hlen); 1134 while (DH_ENTRY(dh, i) == DIRHASH_DEL) { 1135 DH_ENTRY(dh, i) = DIRHASH_EMPTY; 1136 dh->dh_hused--; 1137 i = WRAPDECR(i, dh->dh_hlen); 1138 } 1139 KASSERT(dh->dh_hused >= 0, ("ufsdirhash_delslot neg hlen")); 1140 } 1141 } 1142 1143 /* 1144 * Given a directory entry and its offset, find the offset of the 1145 * previous entry in the same DIRBLKSIZ-sized block. Returns an 1146 * offset, or -1 if there is no previous entry in the block or some 1147 * other problem occurred. 1148 */ 1149 static doff_t 1150 ufsdirhash_getprev(struct direct *dirp, doff_t offset) 1151 { 1152 struct direct *dp; 1153 char *blkbuf; 1154 doff_t blkoff, prevoff; 1155 int entrypos, i; 1156 1157 blkoff = rounddown2(offset, DIRBLKSIZ); /* offset of start of block */ 1158 entrypos = offset & (DIRBLKSIZ - 1); /* entry relative to block */ 1159 blkbuf = (char *)dirp - entrypos; 1160 prevoff = blkoff; 1161 1162 /* If `offset' is the start of a block, there is no previous entry. */ 1163 if (entrypos == 0) 1164 return (-1); 1165 1166 /* Scan from the start of the block until we get to the entry. */ 1167 for (i = 0; i < entrypos; i += dp->d_reclen) { 1168 dp = (struct direct *)(blkbuf + i); 1169 if (dp->d_reclen == 0 || i + dp->d_reclen > entrypos) 1170 return (-1); /* Corrupted directory. */ 1171 prevoff = blkoff + i; 1172 } 1173 return (prevoff); 1174 } 1175 1176 /* 1177 * Delete the given dirhash and reclaim its memory. Assumes that 1178 * ufsdirhash_list is locked, and leaves it locked. Also assumes 1179 * that dh is locked. Returns the amount of memory freed. 1180 */ 1181 static int 1182 ufsdirhash_destroy(struct dirhash *dh) 1183 { 1184 doff_t **hash; 1185 u_int8_t *blkfree; 1186 int i, mem, narrays; 1187 1188 KASSERT(dh->dh_hash != NULL, ("dirhash: NULL hash on list")); 1189 1190 /* Remove it from the list and detach its memory. */ 1191 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 1192 dh->dh_onlist = 0; 1193 hash = dh->dh_hash; 1194 dh->dh_hash = NULL; 1195 blkfree = dh->dh_blkfree; 1196 dh->dh_blkfree = NULL; 1197 narrays = dh->dh_narrays; 1198 mem = dh->dh_memreq; 1199 dh->dh_memreq = 0; 1200 1201 /* Unlock dirhash and free the detached memory. */ 1202 ufsdirhash_release(dh); 1203 for (i = 0; i < narrays; i++) 1204 DIRHASH_BLKFREE(hash[i]); 1205 free(hash, M_DIRHASH); 1206 free(blkfree, M_DIRHASH); 1207 1208 /* Account for the returned memory. */ 1209 ufs_dirhashmem -= mem; 1210 1211 return (mem); 1212 } 1213 1214 /* 1215 * Try to free up `wanted' bytes by stealing memory from existing 1216 * dirhashes. Returns zero with list locked if successful. 1217 */ 1218 static int 1219 ufsdirhash_recycle(int wanted) 1220 { 1221 struct dirhash *dh; 1222 1223 DIRHASHLIST_LOCK(); 1224 dh = TAILQ_FIRST(&ufsdirhash_list); 1225 while (wanted + ufs_dirhashmem > ufs_dirhashmaxmem) { 1226 /* Decrement the score; only recycle if it becomes zero. */ 1227 if (dh == NULL || --dh->dh_score > 0) { 1228 DIRHASHLIST_UNLOCK(); 1229 return (-1); 1230 } 1231 /* 1232 * If we can't lock it it's in use and we don't want to 1233 * recycle it anyway. 1234 */ 1235 if (!sx_try_xlock(&dh->dh_lock)) { 1236 dh = TAILQ_NEXT(dh, dh_list); 1237 continue; 1238 } 1239 1240 ufsdirhash_destroy(dh); 1241 1242 /* Repeat if necessary. */ 1243 dh = TAILQ_FIRST(&ufsdirhash_list); 1244 } 1245 /* Success; return with list locked. */ 1246 return (0); 1247 } 1248 1249 /* 1250 * Callback that frees some dirhashes when the system is low on virtual memory. 1251 */ 1252 static void 1253 ufsdirhash_lowmem() 1254 { 1255 struct dirhash *dh, *dh_temp; 1256 int memfreed, memwanted; 1257 1258 ufs_dirhashlowmemcount++; 1259 memfreed = 0; 1260 memwanted = ufs_dirhashmem * ufs_dirhashreclaimpercent / 100; 1261 1262 DIRHASHLIST_LOCK(); 1263 1264 /* 1265 * Reclaim up to memwanted from the oldest dirhashes. This will allow 1266 * us to make some progress when the system is running out of memory 1267 * without compromising the dinamicity of maximum age. If the situation 1268 * does not improve lowmem will be eventually retriggered and free some 1269 * other entry in the cache. The entries on the head of the list should 1270 * be the oldest. If during list traversal we can't get a lock on the 1271 * dirhash, it will be skipped. 1272 */ 1273 TAILQ_FOREACH_SAFE(dh, &ufsdirhash_list, dh_list, dh_temp) { 1274 if (sx_try_xlock(&dh->dh_lock)) 1275 memfreed += ufsdirhash_destroy(dh); 1276 if (memfreed >= memwanted) 1277 break; 1278 } 1279 DIRHASHLIST_UNLOCK(); 1280 } 1281 1282 static int 1283 ufsdirhash_set_reclaimpercent(SYSCTL_HANDLER_ARGS) 1284 { 1285 int error, v; 1286 1287 v = ufs_dirhashreclaimpercent; 1288 error = sysctl_handle_int(oidp, &v, v, req); 1289 if (error) 1290 return (error); 1291 if (req->newptr == NULL) 1292 return (error); 1293 if (v == ufs_dirhashreclaimpercent) 1294 return (0); 1295 1296 /* Refuse invalid percentages */ 1297 if (v < 0 || v > 100) 1298 return (EINVAL); 1299 ufs_dirhashreclaimpercent = v; 1300 return (0); 1301 } 1302 1303 void 1304 ufsdirhash_init() 1305 { 1306 ufs_dirhashmaxmem = lmax(roundup(hibufspace / 64, PAGE_SIZE), 1307 2 * 1024 * 1024); 1308 1309 ufsdirhash_zone = uma_zcreate("DIRHASH", DH_NBLKOFF * sizeof(doff_t), 1310 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 1311 mtx_init(&ufsdirhash_mtx, "dirhash list", NULL, MTX_DEF); 1312 TAILQ_INIT(&ufsdirhash_list); 1313 1314 /* Register a callback function to handle low memory signals */ 1315 EVENTHANDLER_REGISTER(vm_lowmem, ufsdirhash_lowmem, NULL, 1316 EVENTHANDLER_PRI_FIRST); 1317 } 1318 1319 void 1320 ufsdirhash_uninit() 1321 { 1322 KASSERT(TAILQ_EMPTY(&ufsdirhash_list), ("ufsdirhash_uninit")); 1323 uma_zdestroy(ufsdirhash_zone); 1324 mtx_destroy(&ufsdirhash_mtx); 1325 } 1326 1327 #endif /* UFS_DIRHASH */ 1328