ufs_dirhash.c revision 284021
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: stable/10/sys/ufs/ufs/ufs_dirhash.c 284021 2015-06-05 08:36:25Z kib $"); 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 69static MALLOC_DEFINE(M_DIRHASH, "ufs_dirhash", "UFS directory hash tables"); 70 71static int ufs_mindirhashsize = DIRBLKSIZ * 5; 72SYSCTL_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"); 75static int ufs_dirhashmaxmem = 2 * 1024 * 1024; /* NOTE: initial value. It is 76 tuned in ufsdirhash_init() */ 77SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_maxmem, CTLFLAG_RW, &ufs_dirhashmaxmem, 78 0, "maximum allowed dirhash memory usage"); 79static int ufs_dirhashmem; 80SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_mem, CTLFLAG_RD, &ufs_dirhashmem, 81 0, "current dirhash memory usage"); 82static int ufs_dirhashcheck = 0; 83SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_docheck, CTLFLAG_RW, &ufs_dirhashcheck, 84 0, "enable extra sanity tests"); 85static int ufs_dirhashlowmemcount = 0; 86SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_lowmemcount, CTLFLAG_RD, 87 &ufs_dirhashlowmemcount, 0, "number of times low memory hook called"); 88static int ufs_dirhashreclaimage = 60; 89SYSCTL_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 94static int ufsdirhash_hash(struct dirhash *dh, char *name, int namelen); 95static void ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff); 96static void ufsdirhash_delslot(struct dirhash *dh, int slot); 97static int ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, 98 doff_t offset); 99static doff_t ufsdirhash_getprev(struct direct *dp, doff_t offset); 100static int ufsdirhash_recycle(int wanted); 101static void ufsdirhash_lowmem(void); 102static void ufsdirhash_free_locked(struct inode *ip); 103 104static 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. */ 114static TAILQ_HEAD(, dirhash) ufsdirhash_list; 115 116/* Protects: ufsdirhash_list, `dh_list' field, ufs_dirhashmem. */ 117static 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 152static void 153ufsdirhash_hold(struct dirhash *dh) 154{ 155 156 refcount_acquire(&dh->dh_refcount); 157} 158 159static void 160ufsdirhash_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 */ 172static void 173ufsdirhash_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 */ 186static struct dirhash * 187ufsdirhash_create(struct inode *ip) 188{ 189 struct dirhash *ndh; 190 struct dirhash *dh; 191 struct vnode *vp; 192 193 ndh = dh = NULL; 194 vp = ip->i_vnode; 195 for (;;) { 196 /* Racy check for i_dirhash to prefetch a dirhash structure. */ 197 if (ip->i_dirhash == NULL && ndh == NULL) { 198 ndh = malloc(sizeof *dh, M_DIRHASH, 199 M_NOWAIT | M_ZERO); 200 if (ndh == NULL) 201 return (NULL); 202 refcount_init(&ndh->dh_refcount, 1); 203 204 /* 205 * The DUPOK is to prevent warnings from the 206 * sx_slock() a few lines down which is safe 207 * since the duplicate lock in that case is 208 * the one for this dirhash we are creating 209 * now which has no external references until 210 * after this function returns. 211 */ 212 sx_init_flags(&ndh->dh_lock, "dirhash", SX_DUPOK); 213 sx_xlock(&ndh->dh_lock); 214 } 215 /* 216 * Check i_dirhash. If it's NULL just try to use a 217 * preallocated structure. If none exists loop and try again. 218 */ 219 VI_LOCK(vp); 220 dh = ip->i_dirhash; 221 if (dh == NULL) { 222 ip->i_dirhash = ndh; 223 VI_UNLOCK(vp); 224 if (ndh == NULL) 225 continue; 226 return (ndh); 227 } 228 ufsdirhash_hold(dh); 229 VI_UNLOCK(vp); 230 231 /* Acquire a shared lock on existing hashes. */ 232 sx_slock(&dh->dh_lock); 233 234 /* The hash could've been recycled while we were waiting. */ 235 VI_LOCK(vp); 236 if (ip->i_dirhash != dh) { 237 VI_UNLOCK(vp); 238 ufsdirhash_release(dh); 239 ufsdirhash_drop(dh); 240 continue; 241 } 242 VI_UNLOCK(vp); 243 ufsdirhash_drop(dh); 244 245 /* If the hash is still valid we've succeeded. */ 246 if (dh->dh_hash != NULL) 247 break; 248 /* 249 * If the hash is NULL it has been recycled. Try to upgrade 250 * so we can recreate it. If we fail the upgrade, drop our 251 * lock and try again. 252 */ 253 if (sx_try_upgrade(&dh->dh_lock)) 254 break; 255 sx_sunlock(&dh->dh_lock); 256 } 257 /* Free the preallocated structure if it was not necessary. */ 258 if (ndh) { 259 ufsdirhash_release(ndh); 260 ufsdirhash_drop(ndh); 261 } 262 return (dh); 263} 264 265/* 266 * Acquire an exclusive lock on an existing hash. Requires an exclusive 267 * vnode lock to protect the i_dirhash pointer. hashes that have been 268 * recycled are reclaimed here and NULL is returned. 269 */ 270static struct dirhash * 271ufsdirhash_acquire(struct inode *ip) 272{ 273 struct dirhash *dh; 274 275 ASSERT_VOP_ELOCKED(ip->i_vnode, __FUNCTION__); 276 277 dh = ip->i_dirhash; 278 if (dh == NULL) 279 return (NULL); 280 sx_xlock(&dh->dh_lock); 281 if (dh->dh_hash != NULL) 282 return (dh); 283 ufsdirhash_free_locked(ip); 284 return (NULL); 285} 286 287/* 288 * Acquire exclusively and free the hash pointed to by ip. Works with a 289 * shared or exclusive vnode lock. 290 */ 291void 292ufsdirhash_free(struct inode *ip) 293{ 294 struct dirhash *dh; 295 struct vnode *vp; 296 297 vp = ip->i_vnode; 298 for (;;) { 299 /* Grab a reference on this inode's dirhash if it has one. */ 300 VI_LOCK(vp); 301 dh = ip->i_dirhash; 302 if (dh == NULL) { 303 VI_UNLOCK(vp); 304 return; 305 } 306 ufsdirhash_hold(dh); 307 VI_UNLOCK(vp); 308 309 /* Exclusively lock the dirhash. */ 310 sx_xlock(&dh->dh_lock); 311 312 /* If this dirhash still belongs to this inode, then free it. */ 313 VI_LOCK(vp); 314 if (ip->i_dirhash == dh) { 315 VI_UNLOCK(vp); 316 ufsdirhash_drop(dh); 317 break; 318 } 319 VI_UNLOCK(vp); 320 321 /* 322 * This inode's dirhash has changed while we were 323 * waiting for the dirhash lock, so try again. 324 */ 325 ufsdirhash_release(dh); 326 ufsdirhash_drop(dh); 327 } 328 ufsdirhash_free_locked(ip); 329} 330 331/* 332 * Attempt to build up a hash table for the directory contents in 333 * inode 'ip'. Returns 0 on success, or -1 of the operation failed. 334 */ 335int 336ufsdirhash_build(struct inode *ip) 337{ 338 struct dirhash *dh; 339 struct buf *bp = NULL; 340 struct direct *ep; 341 struct vnode *vp; 342 doff_t bmask, pos; 343 int dirblocks, i, j, memreqd, nblocks, narrays, nslots, slot; 344 345 /* Take care of a decreased sysctl value. */ 346 while (ufs_dirhashmem > ufs_dirhashmaxmem) { 347 if (ufsdirhash_recycle(0) != 0) 348 return (-1); 349 /* Recycled enough memory, so unlock the list. */ 350 DIRHASHLIST_UNLOCK(); 351 } 352 353 /* Check if we can/should use dirhash. */ 354 if (ip->i_size < ufs_mindirhashsize || OFSFMT(ip->i_vnode) || 355 ip->i_effnlink == 0) { 356 if (ip->i_dirhash) 357 ufsdirhash_free(ip); 358 return (-1); 359 } 360 dh = ufsdirhash_create(ip); 361 if (dh == NULL) 362 return (-1); 363 if (dh->dh_hash != NULL) 364 return (0); 365 366 vp = ip->i_vnode; 367 /* Allocate 50% more entries than this dir size could ever need. */ 368 KASSERT(ip->i_size >= DIRBLKSIZ, ("ufsdirhash_build size")); 369 nslots = ip->i_size / DIRECTSIZ(1); 370 nslots = (nslots * 3 + 1) / 2; 371 narrays = howmany(nslots, DH_NBLKOFF); 372 nslots = narrays * DH_NBLKOFF; 373 dirblocks = howmany(ip->i_size, DIRBLKSIZ); 374 nblocks = (dirblocks * 3 + 1) / 2; 375 memreqd = sizeof(*dh) + narrays * sizeof(*dh->dh_hash) + 376 narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) + 377 nblocks * sizeof(*dh->dh_blkfree); 378 DIRHASHLIST_LOCK(); 379 if (memreqd + ufs_dirhashmem > ufs_dirhashmaxmem) { 380 DIRHASHLIST_UNLOCK(); 381 if (memreqd > ufs_dirhashmaxmem / 2) 382 goto fail; 383 /* Try to free some space. */ 384 if (ufsdirhash_recycle(memreqd) != 0) 385 goto fail; 386 /* Enough was freed, and list has been locked. */ 387 } 388 ufs_dirhashmem += memreqd; 389 DIRHASHLIST_UNLOCK(); 390 391 /* Initialise the hash table and block statistics. */ 392 dh->dh_memreq = memreqd; 393 dh->dh_narrays = narrays; 394 dh->dh_hlen = nslots; 395 dh->dh_nblk = nblocks; 396 dh->dh_dirblks = dirblocks; 397 for (i = 0; i < DH_NFSTATS; i++) 398 dh->dh_firstfree[i] = -1; 399 dh->dh_firstfree[DH_NFSTATS] = 0; 400 dh->dh_hused = 0; 401 dh->dh_seqoff = -1; 402 dh->dh_score = DH_SCOREINIT; 403 dh->dh_lastused = time_second; 404 405 /* 406 * Use non-blocking mallocs so that we will revert to a linear 407 * lookup on failure rather than potentially blocking forever. 408 */ 409 dh->dh_hash = malloc(narrays * sizeof(dh->dh_hash[0]), 410 M_DIRHASH, M_NOWAIT | M_ZERO); 411 if (dh->dh_hash == NULL) 412 goto fail; 413 dh->dh_blkfree = malloc(nblocks * sizeof(dh->dh_blkfree[0]), 414 M_DIRHASH, M_NOWAIT); 415 if (dh->dh_blkfree == NULL) 416 goto fail; 417 for (i = 0; i < narrays; i++) { 418 if ((dh->dh_hash[i] = DIRHASH_BLKALLOC_WAITOK()) == NULL) 419 goto fail; 420 for (j = 0; j < DH_NBLKOFF; j++) 421 dh->dh_hash[i][j] = DIRHASH_EMPTY; 422 } 423 for (i = 0; i < dirblocks; i++) 424 dh->dh_blkfree[i] = DIRBLKSIZ / DIRALIGN; 425 bmask = vp->v_mount->mnt_stat.f_iosize - 1; 426 pos = 0; 427 while (pos < ip->i_size) { 428 /* If necessary, get the next directory block. */ 429 if ((pos & bmask) == 0) { 430 if (bp != NULL) 431 brelse(bp); 432 if (UFS_BLKATOFF(vp, (off_t)pos, NULL, &bp) != 0) 433 goto fail; 434 } 435 436 /* Add this entry to the hash. */ 437 ep = (struct direct *)((char *)bp->b_data + (pos & bmask)); 438 if (ep->d_reclen == 0 || ep->d_reclen > 439 DIRBLKSIZ - (pos & (DIRBLKSIZ - 1))) { 440 /* Corrupted directory. */ 441 brelse(bp); 442 goto fail; 443 } 444 if (ep->d_ino != 0) { 445 /* Add the entry (simplified ufsdirhash_add). */ 446 slot = ufsdirhash_hash(dh, ep->d_name, ep->d_namlen); 447 while (DH_ENTRY(dh, slot) != DIRHASH_EMPTY) 448 slot = WRAPINCR(slot, dh->dh_hlen); 449 dh->dh_hused++; 450 DH_ENTRY(dh, slot) = pos; 451 ufsdirhash_adjfree(dh, pos, -DIRSIZ(0, ep)); 452 } 453 pos += ep->d_reclen; 454 } 455 456 if (bp != NULL) 457 brelse(bp); 458 DIRHASHLIST_LOCK(); 459 TAILQ_INSERT_TAIL(&ufsdirhash_list, dh, dh_list); 460 dh->dh_onlist = 1; 461 DIRHASHLIST_UNLOCK(); 462 sx_downgrade(&dh->dh_lock); 463 return (0); 464 465fail: 466 ufsdirhash_free_locked(ip); 467 return (-1); 468} 469 470/* 471 * Free any hash table associated with inode 'ip'. 472 */ 473static void 474ufsdirhash_free_locked(struct inode *ip) 475{ 476 struct dirhash *dh; 477 struct vnode *vp; 478 int i; 479 480 DIRHASH_ASSERT_LOCKED(ip->i_dirhash); 481 482 /* 483 * Clear the pointer in the inode to prevent new threads from 484 * finding the dead structure. 485 */ 486 vp = ip->i_vnode; 487 VI_LOCK(vp); 488 dh = ip->i_dirhash; 489 ip->i_dirhash = NULL; 490 VI_UNLOCK(vp); 491 492 /* 493 * Remove the hash from the list since we are going to free its 494 * memory. 495 */ 496 DIRHASHLIST_LOCK(); 497 if (dh->dh_onlist) 498 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 499 ufs_dirhashmem -= dh->dh_memreq; 500 DIRHASHLIST_UNLOCK(); 501 502 /* 503 * At this point, any waiters for the lock should hold their 504 * own reference on the dirhash structure. They will drop 505 * that reference once they grab the vnode interlock and see 506 * that ip->i_dirhash is NULL. 507 */ 508 sx_xunlock(&dh->dh_lock); 509 510 /* 511 * Handle partially recycled as well as fully constructed hashes. 512 */ 513 if (dh->dh_hash != NULL) { 514 for (i = 0; i < dh->dh_narrays; i++) 515 if (dh->dh_hash[i] != NULL) 516 DIRHASH_BLKFREE(dh->dh_hash[i]); 517 free(dh->dh_hash, M_DIRHASH); 518 if (dh->dh_blkfree != NULL) 519 free(dh->dh_blkfree, M_DIRHASH); 520 } 521 522 /* 523 * Drop the inode's reference to the data structure. 524 */ 525 ufsdirhash_drop(dh); 526} 527 528/* 529 * Find the offset of the specified name within the given inode. 530 * Returns 0 on success, ENOENT if the entry does not exist, or 531 * EJUSTRETURN if the caller should revert to a linear search. 532 * 533 * If successful, the directory offset is stored in *offp, and a 534 * pointer to a struct buf containing the entry is stored in *bpp. If 535 * prevoffp is non-NULL, the offset of the previous entry within 536 * the DIRBLKSIZ-sized block is stored in *prevoffp (if the entry 537 * is the first in a block, the start of the block is used). 538 * 539 * Must be called with the hash locked. Returns with the hash unlocked. 540 */ 541int 542ufsdirhash_lookup(struct inode *ip, char *name, int namelen, doff_t *offp, 543 struct buf **bpp, doff_t *prevoffp) 544{ 545 struct dirhash *dh, *dh_next; 546 struct direct *dp; 547 struct vnode *vp; 548 struct buf *bp; 549 doff_t blkoff, bmask, offset, prevoff, seqoff; 550 int i, slot; 551 int error; 552 553 dh = ip->i_dirhash; 554 KASSERT(dh != NULL && dh->dh_hash != NULL, 555 ("ufsdirhash_lookup: Invalid dirhash %p\n", dh)); 556 DIRHASH_ASSERT_LOCKED(dh); 557 /* 558 * Move this dirhash towards the end of the list if it has a 559 * score higher than the next entry, and acquire the dh_lock. 560 */ 561 DIRHASHLIST_LOCK(); 562 if (TAILQ_NEXT(dh, dh_list) != NULL) { 563 /* 564 * If the new score will be greater than that of the next 565 * entry, then move this entry past it. With both mutexes 566 * held, dh_next won't go away, but its dh_score could 567 * change; that's not important since it is just a hint. 568 */ 569 if ((dh_next = TAILQ_NEXT(dh, dh_list)) != NULL && 570 dh->dh_score >= dh_next->dh_score) { 571 KASSERT(dh->dh_onlist, ("dirhash: not on list")); 572 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 573 TAILQ_INSERT_AFTER(&ufsdirhash_list, dh_next, dh, 574 dh_list); 575 } 576 } 577 /* Update the score. */ 578 if (dh->dh_score < DH_SCOREMAX) 579 dh->dh_score++; 580 581 /* Update last used time. */ 582 dh->dh_lastused = time_second; 583 DIRHASHLIST_UNLOCK(); 584 585 vp = ip->i_vnode; 586 bmask = vp->v_mount->mnt_stat.f_iosize - 1; 587 blkoff = -1; 588 bp = NULL; 589 seqoff = dh->dh_seqoff; 590restart: 591 slot = ufsdirhash_hash(dh, name, namelen); 592 593 if (seqoff != -1) { 594 /* 595 * Sequential access optimisation. seqoff contains the 596 * offset of the directory entry immediately following 597 * the last entry that was looked up. Check if this offset 598 * appears in the hash chain for the name we are looking for. 599 */ 600 for (i = slot; (offset = DH_ENTRY(dh, i)) != DIRHASH_EMPTY; 601 i = WRAPINCR(i, dh->dh_hlen)) 602 if (offset == seqoff) 603 break; 604 if (offset == seqoff) { 605 /* 606 * We found an entry with the expected offset. This 607 * is probably the entry we want, but if not, the 608 * code below will retry. 609 */ 610 slot = i; 611 } else 612 seqoff = -1; 613 } 614 615 for (; (offset = DH_ENTRY(dh, slot)) != DIRHASH_EMPTY; 616 slot = WRAPINCR(slot, dh->dh_hlen)) { 617 if (offset == DIRHASH_DEL) 618 continue; 619 if (offset < 0 || offset >= ip->i_size) 620 panic("ufsdirhash_lookup: bad offset in hash array"); 621 if ((offset & ~bmask) != blkoff) { 622 if (bp != NULL) 623 brelse(bp); 624 blkoff = offset & ~bmask; 625 if (UFS_BLKATOFF(vp, (off_t)blkoff, NULL, &bp) != 0) { 626 error = EJUSTRETURN; 627 goto fail; 628 } 629 } 630 KASSERT(bp != NULL, ("no buffer allocated")); 631 dp = (struct direct *)(bp->b_data + (offset & bmask)); 632 if (dp->d_reclen == 0 || dp->d_reclen > 633 DIRBLKSIZ - (offset & (DIRBLKSIZ - 1))) { 634 /* Corrupted directory. */ 635 error = EJUSTRETURN; 636 goto fail; 637 } 638 if (dp->d_namlen == namelen && 639 bcmp(dp->d_name, name, namelen) == 0) { 640 /* Found. Get the prev offset if needed. */ 641 if (prevoffp != NULL) { 642 if (offset & (DIRBLKSIZ - 1)) { 643 prevoff = ufsdirhash_getprev(dp, 644 offset); 645 if (prevoff == -1) { 646 error = EJUSTRETURN; 647 goto fail; 648 } 649 } else 650 prevoff = offset; 651 *prevoffp = prevoff; 652 } 653 654 /* Update offset. */ 655 dh->dh_seqoff = offset + DIRSIZ(0, dp); 656 *bpp = bp; 657 *offp = offset; 658 ufsdirhash_release(dh); 659 return (0); 660 } 661 662 /* 663 * When the name doesn't match in the sequential 664 * optimization case, go back and search normally. 665 */ 666 if (seqoff != -1) { 667 seqoff = -1; 668 goto restart; 669 } 670 } 671 error = ENOENT; 672fail: 673 ufsdirhash_release(dh); 674 if (bp != NULL) 675 brelse(bp); 676 return (error); 677} 678 679/* 680 * Find a directory block with room for 'slotneeded' bytes. Returns 681 * the offset of the directory entry that begins the free space. 682 * This will either be the offset of an existing entry that has free 683 * space at the end, or the offset of an entry with d_ino == 0 at 684 * the start of a DIRBLKSIZ block. 685 * 686 * To use the space, the caller may need to compact existing entries in 687 * the directory. The total number of bytes in all of the entries involved 688 * in the compaction is stored in *slotsize. In other words, all of 689 * the entries that must be compacted are exactly contained in the 690 * region beginning at the returned offset and spanning *slotsize bytes. 691 * 692 * Returns -1 if no space was found, indicating that the directory 693 * must be extended. 694 */ 695doff_t 696ufsdirhash_findfree(struct inode *ip, int slotneeded, int *slotsize) 697{ 698 struct direct *dp; 699 struct dirhash *dh; 700 struct buf *bp; 701 doff_t pos, slotstart; 702 int dirblock, error, freebytes, i; 703 704 dh = ip->i_dirhash; 705 KASSERT(dh != NULL && dh->dh_hash != NULL, 706 ("ufsdirhash_findfree: Invalid dirhash %p\n", dh)); 707 DIRHASH_ASSERT_LOCKED(dh); 708 709 /* Find a directory block with the desired free space. */ 710 dirblock = -1; 711 for (i = howmany(slotneeded, DIRALIGN); i <= DH_NFSTATS; i++) 712 if ((dirblock = dh->dh_firstfree[i]) != -1) 713 break; 714 if (dirblock == -1) 715 return (-1); 716 717 KASSERT(dirblock < dh->dh_nblk && 718 dh->dh_blkfree[dirblock] >= howmany(slotneeded, DIRALIGN), 719 ("ufsdirhash_findfree: bad stats")); 720 pos = dirblock * DIRBLKSIZ; 721 error = UFS_BLKATOFF(ip->i_vnode, (off_t)pos, (char **)&dp, &bp); 722 if (error) 723 return (-1); 724 725 /* Find the first entry with free space. */ 726 for (i = 0; i < DIRBLKSIZ; ) { 727 if (dp->d_reclen == 0) { 728 brelse(bp); 729 return (-1); 730 } 731 if (dp->d_ino == 0 || dp->d_reclen > DIRSIZ(0, dp)) 732 break; 733 i += dp->d_reclen; 734 dp = (struct direct *)((char *)dp + dp->d_reclen); 735 } 736 if (i > DIRBLKSIZ) { 737 brelse(bp); 738 return (-1); 739 } 740 slotstart = pos + i; 741 742 /* Find the range of entries needed to get enough space */ 743 freebytes = 0; 744 while (i < DIRBLKSIZ && freebytes < slotneeded) { 745 freebytes += dp->d_reclen; 746 if (dp->d_ino != 0) 747 freebytes -= DIRSIZ(0, dp); 748 if (dp->d_reclen == 0) { 749 brelse(bp); 750 return (-1); 751 } 752 i += dp->d_reclen; 753 dp = (struct direct *)((char *)dp + dp->d_reclen); 754 } 755 if (i > DIRBLKSIZ) { 756 brelse(bp); 757 return (-1); 758 } 759 if (freebytes < slotneeded) 760 panic("ufsdirhash_findfree: free mismatch"); 761 brelse(bp); 762 *slotsize = pos + i - slotstart; 763 return (slotstart); 764} 765 766/* 767 * Return the start of the unused space at the end of a directory, or 768 * -1 if there are no trailing unused blocks. 769 */ 770doff_t 771ufsdirhash_enduseful(struct inode *ip) 772{ 773 774 struct dirhash *dh; 775 int i; 776 777 dh = ip->i_dirhash; 778 DIRHASH_ASSERT_LOCKED(dh); 779 KASSERT(dh != NULL && dh->dh_hash != NULL, 780 ("ufsdirhash_enduseful: Invalid dirhash %p\n", dh)); 781 782 if (dh->dh_blkfree[dh->dh_dirblks - 1] != DIRBLKSIZ / DIRALIGN) 783 return (-1); 784 785 for (i = dh->dh_dirblks - 1; i >= 0; i--) 786 if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN) 787 break; 788 789 return ((doff_t)(i + 1) * DIRBLKSIZ); 790} 791 792/* 793 * Insert information into the hash about a new directory entry. dirp 794 * points to a struct direct containing the entry, and offset specifies 795 * the offset of this entry. 796 */ 797void 798ufsdirhash_add(struct inode *ip, struct direct *dirp, doff_t offset) 799{ 800 struct dirhash *dh; 801 int slot; 802 803 if ((dh = ufsdirhash_acquire(ip)) == NULL) 804 return; 805 806 KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ, 807 ("ufsdirhash_add: bad offset")); 808 /* 809 * Normal hash usage is < 66%. If the usage gets too high then 810 * remove the hash entirely and let it be rebuilt later. 811 */ 812 if (dh->dh_hused >= (dh->dh_hlen * 3) / 4) { 813 ufsdirhash_free_locked(ip); 814 return; 815 } 816 817 /* Find a free hash slot (empty or deleted), and add the entry. */ 818 slot = ufsdirhash_hash(dh, dirp->d_name, dirp->d_namlen); 819 while (DH_ENTRY(dh, slot) >= 0) 820 slot = WRAPINCR(slot, dh->dh_hlen); 821 if (DH_ENTRY(dh, slot) == DIRHASH_EMPTY) 822 dh->dh_hused++; 823 DH_ENTRY(dh, slot) = offset; 824 825 /* Update last used time. */ 826 dh->dh_lastused = time_second; 827 828 /* Update the per-block summary info. */ 829 ufsdirhash_adjfree(dh, offset, -DIRSIZ(0, dirp)); 830 ufsdirhash_release(dh); 831} 832 833/* 834 * Remove the specified directory entry from the hash. The entry to remove 835 * is defined by the name in `dirp', which must exist at the specified 836 * `offset' within the directory. 837 */ 838void 839ufsdirhash_remove(struct inode *ip, struct direct *dirp, doff_t offset) 840{ 841 struct dirhash *dh; 842 int slot; 843 844 if ((dh = ufsdirhash_acquire(ip)) == NULL) 845 return; 846 847 KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ, 848 ("ufsdirhash_remove: bad offset")); 849 /* Find the entry */ 850 slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, offset); 851 852 /* Remove the hash entry. */ 853 ufsdirhash_delslot(dh, slot); 854 855 /* Update the per-block summary info. */ 856 ufsdirhash_adjfree(dh, offset, DIRSIZ(0, dirp)); 857 ufsdirhash_release(dh); 858} 859 860/* 861 * Change the offset associated with a directory entry in the hash. Used 862 * when compacting directory blocks. 863 */ 864void 865ufsdirhash_move(struct inode *ip, struct direct *dirp, doff_t oldoff, 866 doff_t newoff) 867{ 868 struct dirhash *dh; 869 int slot; 870 871 if ((dh = ufsdirhash_acquire(ip)) == NULL) 872 return; 873 874 KASSERT(oldoff < dh->dh_dirblks * DIRBLKSIZ && 875 newoff < dh->dh_dirblks * DIRBLKSIZ, 876 ("ufsdirhash_move: bad offset")); 877 /* Find the entry, and update the offset. */ 878 slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, oldoff); 879 DH_ENTRY(dh, slot) = newoff; 880 ufsdirhash_release(dh); 881} 882 883/* 884 * Inform dirhash that the directory has grown by one block that 885 * begins at offset (i.e. the new length is offset + DIRBLKSIZ). 886 */ 887void 888ufsdirhash_newblk(struct inode *ip, doff_t offset) 889{ 890 struct dirhash *dh; 891 int block; 892 893 if ((dh = ufsdirhash_acquire(ip)) == NULL) 894 return; 895 896 KASSERT(offset == dh->dh_dirblks * DIRBLKSIZ, 897 ("ufsdirhash_newblk: bad offset")); 898 block = offset / DIRBLKSIZ; 899 if (block >= dh->dh_nblk) { 900 /* Out of space; must rebuild. */ 901 ufsdirhash_free_locked(ip); 902 return; 903 } 904 dh->dh_dirblks = block + 1; 905 906 /* Account for the new free block. */ 907 dh->dh_blkfree[block] = DIRBLKSIZ / DIRALIGN; 908 if (dh->dh_firstfree[DH_NFSTATS] == -1) 909 dh->dh_firstfree[DH_NFSTATS] = block; 910 ufsdirhash_release(dh); 911} 912 913/* 914 * Inform dirhash that the directory is being truncated. 915 */ 916void 917ufsdirhash_dirtrunc(struct inode *ip, doff_t offset) 918{ 919 struct dirhash *dh; 920 int block, i; 921 922 if ((dh = ufsdirhash_acquire(ip)) == NULL) 923 return; 924 925 KASSERT(offset <= dh->dh_dirblks * DIRBLKSIZ, 926 ("ufsdirhash_dirtrunc: bad offset")); 927 block = howmany(offset, DIRBLKSIZ); 928 /* 929 * If the directory shrinks to less than 1/8 of dh_nblk blocks 930 * (about 20% of its original size due to the 50% extra added in 931 * ufsdirhash_build) then free it, and let the caller rebuild 932 * if necessary. 933 */ 934 if (block < dh->dh_nblk / 8 && dh->dh_narrays > 1) { 935 ufsdirhash_free_locked(ip); 936 return; 937 } 938 939 /* 940 * Remove any `first free' information pertaining to the 941 * truncated blocks. All blocks we're removing should be 942 * completely unused. 943 */ 944 if (dh->dh_firstfree[DH_NFSTATS] >= block) 945 dh->dh_firstfree[DH_NFSTATS] = -1; 946 for (i = block; i < dh->dh_dirblks; i++) 947 if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN) 948 panic("ufsdirhash_dirtrunc: blocks in use"); 949 for (i = 0; i < DH_NFSTATS; i++) 950 if (dh->dh_firstfree[i] >= block) 951 panic("ufsdirhash_dirtrunc: first free corrupt"); 952 dh->dh_dirblks = block; 953 ufsdirhash_release(dh); 954} 955 956/* 957 * Debugging function to check that the dirhash information about 958 * a directory block matches its actual contents. Panics if a mismatch 959 * is detected. 960 * 961 * On entry, `buf' should point to the start of an in-core 962 * DIRBLKSIZ-sized directory block, and `offset' should contain the 963 * offset from the start of the directory of that block. 964 */ 965void 966ufsdirhash_checkblock(struct inode *ip, char *buf, doff_t offset) 967{ 968 struct dirhash *dh; 969 struct direct *dp; 970 int block, ffslot, i, nfree; 971 972 if (!ufs_dirhashcheck) 973 return; 974 if ((dh = ufsdirhash_acquire(ip)) == NULL) 975 return; 976 977 block = offset / DIRBLKSIZ; 978 if ((offset & (DIRBLKSIZ - 1)) != 0 || block >= dh->dh_dirblks) 979 panic("ufsdirhash_checkblock: bad offset"); 980 981 nfree = 0; 982 for (i = 0; i < DIRBLKSIZ; i += dp->d_reclen) { 983 dp = (struct direct *)(buf + i); 984 if (dp->d_reclen == 0 || i + dp->d_reclen > DIRBLKSIZ) 985 panic("ufsdirhash_checkblock: bad dir"); 986 987 if (dp->d_ino == 0) { 988#if 0 989 /* 990 * XXX entries with d_ino == 0 should only occur 991 * at the start of a DIRBLKSIZ block. However the 992 * ufs code is tolerant of such entries at other 993 * offsets, and fsck does not fix them. 994 */ 995 if (i != 0) 996 panic("ufsdirhash_checkblock: bad dir inode"); 997#endif 998 nfree += dp->d_reclen; 999 continue; 1000 } 1001 1002 /* Check that the entry exists (will panic if it doesn't). */ 1003 ufsdirhash_findslot(dh, dp->d_name, dp->d_namlen, offset + i); 1004 1005 nfree += dp->d_reclen - DIRSIZ(0, dp); 1006 } 1007 if (i != DIRBLKSIZ) 1008 panic("ufsdirhash_checkblock: bad dir end"); 1009 1010 if (dh->dh_blkfree[block] * DIRALIGN != nfree) 1011 panic("ufsdirhash_checkblock: bad free count"); 1012 1013 ffslot = BLKFREE2IDX(nfree / DIRALIGN); 1014 for (i = 0; i <= DH_NFSTATS; i++) 1015 if (dh->dh_firstfree[i] == block && i != ffslot) 1016 panic("ufsdirhash_checkblock: bad first-free"); 1017 if (dh->dh_firstfree[ffslot] == -1) 1018 panic("ufsdirhash_checkblock: missing first-free entry"); 1019 ufsdirhash_release(dh); 1020} 1021 1022/* 1023 * Hash the specified filename into a dirhash slot. 1024 */ 1025static int 1026ufsdirhash_hash(struct dirhash *dh, char *name, int namelen) 1027{ 1028 u_int32_t hash; 1029 1030 /* 1031 * We hash the name and then some other bit of data that is 1032 * invariant over the dirhash's lifetime. Otherwise names 1033 * differing only in the last byte are placed close to one 1034 * another in the table, which is bad for linear probing. 1035 */ 1036 hash = fnv_32_buf(name, namelen, FNV1_32_INIT); 1037 hash = fnv_32_buf(&dh, sizeof(dh), hash); 1038 return (hash % dh->dh_hlen); 1039} 1040 1041/* 1042 * Adjust the number of free bytes in the block containing `offset' 1043 * by the value specified by `diff'. 1044 * 1045 * The caller must ensure we have exclusive access to `dh'; normally 1046 * that means that dh_lock should be held, but this is also called 1047 * from ufsdirhash_build() where exclusive access can be assumed. 1048 */ 1049static void 1050ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff) 1051{ 1052 int block, i, nfidx, ofidx; 1053 1054 /* Update the per-block summary info. */ 1055 block = offset / DIRBLKSIZ; 1056 KASSERT(block < dh->dh_nblk && block < dh->dh_dirblks, 1057 ("dirhash bad offset")); 1058 ofidx = BLKFREE2IDX(dh->dh_blkfree[block]); 1059 dh->dh_blkfree[block] = (int)dh->dh_blkfree[block] + (diff / DIRALIGN); 1060 nfidx = BLKFREE2IDX(dh->dh_blkfree[block]); 1061 1062 /* Update the `first free' list if necessary. */ 1063 if (ofidx != nfidx) { 1064 /* If removing, scan forward for the next block. */ 1065 if (dh->dh_firstfree[ofidx] == block) { 1066 for (i = block + 1; i < dh->dh_dirblks; i++) 1067 if (BLKFREE2IDX(dh->dh_blkfree[i]) == ofidx) 1068 break; 1069 dh->dh_firstfree[ofidx] = (i < dh->dh_dirblks) ? i : -1; 1070 } 1071 1072 /* Make this the new `first free' if necessary */ 1073 if (dh->dh_firstfree[nfidx] > block || 1074 dh->dh_firstfree[nfidx] == -1) 1075 dh->dh_firstfree[nfidx] = block; 1076 } 1077} 1078 1079/* 1080 * Find the specified name which should have the specified offset. 1081 * Returns a slot number, and panics on failure. 1082 * 1083 * `dh' must be locked on entry and remains so on return. 1084 */ 1085static int 1086ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, doff_t offset) 1087{ 1088 int slot; 1089 1090 DIRHASH_ASSERT_LOCKED(dh); 1091 1092 /* Find the entry. */ 1093 KASSERT(dh->dh_hused < dh->dh_hlen, ("dirhash find full")); 1094 slot = ufsdirhash_hash(dh, name, namelen); 1095 while (DH_ENTRY(dh, slot) != offset && 1096 DH_ENTRY(dh, slot) != DIRHASH_EMPTY) 1097 slot = WRAPINCR(slot, dh->dh_hlen); 1098 if (DH_ENTRY(dh, slot) != offset) 1099 panic("ufsdirhash_findslot: '%.*s' not found", namelen, name); 1100 1101 return (slot); 1102} 1103 1104/* 1105 * Remove the entry corresponding to the specified slot from the hash array. 1106 * 1107 * `dh' must be locked on entry and remains so on return. 1108 */ 1109static void 1110ufsdirhash_delslot(struct dirhash *dh, int slot) 1111{ 1112 int i; 1113 1114 DIRHASH_ASSERT_LOCKED(dh); 1115 1116 /* Mark the entry as deleted. */ 1117 DH_ENTRY(dh, slot) = DIRHASH_DEL; 1118 1119 /* If this is the end of a chain of DIRHASH_DEL slots, remove them. */ 1120 for (i = slot; DH_ENTRY(dh, i) == DIRHASH_DEL; ) 1121 i = WRAPINCR(i, dh->dh_hlen); 1122 if (DH_ENTRY(dh, i) == DIRHASH_EMPTY) { 1123 i = WRAPDECR(i, dh->dh_hlen); 1124 while (DH_ENTRY(dh, i) == DIRHASH_DEL) { 1125 DH_ENTRY(dh, i) = DIRHASH_EMPTY; 1126 dh->dh_hused--; 1127 i = WRAPDECR(i, dh->dh_hlen); 1128 } 1129 KASSERT(dh->dh_hused >= 0, ("ufsdirhash_delslot neg hlen")); 1130 } 1131} 1132 1133/* 1134 * Given a directory entry and its offset, find the offset of the 1135 * previous entry in the same DIRBLKSIZ-sized block. Returns an 1136 * offset, or -1 if there is no previous entry in the block or some 1137 * other problem occurred. 1138 */ 1139static doff_t 1140ufsdirhash_getprev(struct direct *dirp, doff_t offset) 1141{ 1142 struct direct *dp; 1143 char *blkbuf; 1144 doff_t blkoff, prevoff; 1145 int entrypos, i; 1146 1147 blkoff = offset & ~(DIRBLKSIZ - 1); /* offset of start of block */ 1148 entrypos = offset & (DIRBLKSIZ - 1); /* entry relative to block */ 1149 blkbuf = (char *)dirp - entrypos; 1150 prevoff = blkoff; 1151 1152 /* If `offset' is the start of a block, there is no previous entry. */ 1153 if (entrypos == 0) 1154 return (-1); 1155 1156 /* Scan from the start of the block until we get to the entry. */ 1157 for (i = 0; i < entrypos; i += dp->d_reclen) { 1158 dp = (struct direct *)(blkbuf + i); 1159 if (dp->d_reclen == 0 || i + dp->d_reclen > entrypos) 1160 return (-1); /* Corrupted directory. */ 1161 prevoff = blkoff + i; 1162 } 1163 return (prevoff); 1164} 1165 1166/* 1167 * Delete the given dirhash and reclaim its memory. Assumes that 1168 * ufsdirhash_list is locked, and leaves it locked. Also assumes 1169 * that dh is locked. Returns the amount of memory freed. 1170 */ 1171static int 1172ufsdirhash_destroy(struct dirhash *dh) 1173{ 1174 doff_t **hash; 1175 u_int8_t *blkfree; 1176 int i, mem, narrays; 1177 1178 KASSERT(dh->dh_hash != NULL, ("dirhash: NULL hash on list")); 1179 1180 /* Remove it from the list and detach its memory. */ 1181 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 1182 dh->dh_onlist = 0; 1183 hash = dh->dh_hash; 1184 dh->dh_hash = NULL; 1185 blkfree = dh->dh_blkfree; 1186 dh->dh_blkfree = NULL; 1187 narrays = dh->dh_narrays; 1188 mem = dh->dh_memreq; 1189 dh->dh_memreq = 0; 1190 1191 /* Unlock dirhash and free the detached memory. */ 1192 ufsdirhash_release(dh); 1193 for (i = 0; i < narrays; i++) 1194 DIRHASH_BLKFREE(hash[i]); 1195 free(hash, M_DIRHASH); 1196 free(blkfree, M_DIRHASH); 1197 1198 /* Account for the returned memory. */ 1199 ufs_dirhashmem -= mem; 1200 1201 return (mem); 1202} 1203 1204/* 1205 * Try to free up `wanted' bytes by stealing memory from existing 1206 * dirhashes. Returns zero with list locked if successful. 1207 */ 1208static int 1209ufsdirhash_recycle(int wanted) 1210{ 1211 struct dirhash *dh; 1212 1213 DIRHASHLIST_LOCK(); 1214 dh = TAILQ_FIRST(&ufsdirhash_list); 1215 while (wanted + ufs_dirhashmem > ufs_dirhashmaxmem) { 1216 /* Decrement the score; only recycle if it becomes zero. */ 1217 if (dh == NULL || --dh->dh_score > 0) { 1218 DIRHASHLIST_UNLOCK(); 1219 return (-1); 1220 } 1221 /* 1222 * If we can't lock it it's in use and we don't want to 1223 * recycle it anyway. 1224 */ 1225 if (!sx_try_xlock(&dh->dh_lock)) { 1226 dh = TAILQ_NEXT(dh, dh_list); 1227 continue; 1228 } 1229 1230 ufsdirhash_destroy(dh); 1231 1232 /* Repeat if necessary. */ 1233 dh = TAILQ_FIRST(&ufsdirhash_list); 1234 } 1235 /* Success; return with list locked. */ 1236 return (0); 1237} 1238 1239/* 1240 * Callback that frees some dirhashes when the system is low on virtual memory. 1241 */ 1242static void 1243ufsdirhash_lowmem() 1244{ 1245 struct dirhash *dh, *dh_temp; 1246 int memfreed = 0; 1247 /* 1248 * Will free a *minimum* of 10% of the dirhash, but possibly much 1249 * more (depending on dirhashreclaimage). System with large dirhashes 1250 * probably also need a much larger dirhashreclaimage. 1251 * XXX: this percentage may need to be adjusted. 1252 */ 1253 int memwanted = ufs_dirhashmem / 10; 1254 1255 ufs_dirhashlowmemcount++; 1256 1257 DIRHASHLIST_LOCK(); 1258 /* 1259 * Delete dirhashes not used for more than ufs_dirhashreclaimage 1260 * seconds. If we can't get a lock on the dirhash, it will be skipped. 1261 */ 1262 TAILQ_FOREACH_SAFE(dh, &ufsdirhash_list, dh_list, dh_temp) { 1263 if (!sx_try_xlock(&dh->dh_lock)) 1264 continue; 1265 if (time_second - dh->dh_lastused > ufs_dirhashreclaimage) 1266 memfreed += ufsdirhash_destroy(dh); 1267 /* Unlock if we didn't delete the dirhash */ 1268 else 1269 ufsdirhash_release(dh); 1270 } 1271 1272 /* 1273 * If not enough memory was freed, keep deleting hashes from the head 1274 * of the dirhash list. The ones closest to the head should be the 1275 * oldest. 1276 */ 1277 if (memfreed < memwanted) { 1278 TAILQ_FOREACH_SAFE(dh, &ufsdirhash_list, dh_list, dh_temp) { 1279 if (!sx_try_xlock(&dh->dh_lock)) 1280 continue; 1281 memfreed += ufsdirhash_destroy(dh); 1282 if (memfreed >= memwanted) 1283 break; 1284 } 1285 } 1286 DIRHASHLIST_UNLOCK(); 1287} 1288 1289 1290void 1291ufsdirhash_init() 1292{ 1293 ufs_dirhashmaxmem = lmax(roundup(hibufspace / 64, PAGE_SIZE), 1294 2 * 1024 * 1024); 1295 1296 ufsdirhash_zone = uma_zcreate("DIRHASH", DH_NBLKOFF * sizeof(doff_t), 1297 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 1298 mtx_init(&ufsdirhash_mtx, "dirhash list", NULL, MTX_DEF); 1299 TAILQ_INIT(&ufsdirhash_list); 1300 1301 /* Register a callback function to handle low memory signals */ 1302 EVENTHANDLER_REGISTER(vm_lowmem, ufsdirhash_lowmem, NULL, 1303 EVENTHANDLER_PRI_FIRST); 1304} 1305 1306void 1307ufsdirhash_uninit() 1308{ 1309 KASSERT(TAILQ_EMPTY(&ufsdirhash_list), ("ufsdirhash_uninit")); 1310 uma_zdestroy(ufsdirhash_zone); 1311 mtx_destroy(&ufsdirhash_mtx); 1312} 1313 1314#endif /* UFS_DIRHASH */ 1315