ufs_dirhash.c revision 184651
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: head/sys/ufs/ufs/ufs_dirhash.c 184651 2008-11-04 18:56:12Z jhb $"); 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 <vm/uma.h> 53 54#include <ufs/ufs/quota.h> 55#include <ufs/ufs/inode.h> 56#include <ufs/ufs/dir.h> 57#include <ufs/ufs/dirhash.h> 58#include <ufs/ufs/extattr.h> 59#include <ufs/ufs/ufsmount.h> 60#include <ufs/ufs/ufs_extern.h> 61 62#define WRAPINCR(val, limit) (((val) + 1 == (limit)) ? 0 : ((val) + 1)) 63#define WRAPDECR(val, limit) (((val) == 0) ? ((limit) - 1) : ((val) - 1)) 64#define OFSFMT(vp) ((vp)->v_mount->mnt_maxsymlinklen <= 0) 65#define BLKFREE2IDX(n) ((n) > DH_NFSTATS ? DH_NFSTATS : (n)) 66 67static MALLOC_DEFINE(M_DIRHASH, "ufs_dirhash", "UFS directory hash tables"); 68 69static SYSCTL_NODE(_vfs, OID_AUTO, ufs, CTLFLAG_RD, 0, "UFS filesystem"); 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; 76SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_maxmem, CTLFLAG_RW, &ufs_dirhashmaxmem, 77 0, "maximum allowed dirhash memory usage"); 78static int ufs_dirhashmem; 79SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_mem, CTLFLAG_RD, &ufs_dirhashmem, 80 0, "current dirhash memory usage"); 81static int ufs_dirhashcheck = 0; 82SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_docheck, CTLFLAG_RW, &ufs_dirhashcheck, 83 0, "enable extra sanity tests"); 84 85 86static int ufsdirhash_hash(struct dirhash *dh, char *name, int namelen); 87static void ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff); 88static void ufsdirhash_delslot(struct dirhash *dh, int slot); 89static int ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, 90 doff_t offset); 91static doff_t ufsdirhash_getprev(struct direct *dp, doff_t offset); 92static int ufsdirhash_recycle(int wanted); 93static void ufsdirhash_free_locked(struct inode *ip); 94 95static uma_zone_t ufsdirhash_zone; 96 97#define DIRHASHLIST_LOCK() mtx_lock(&ufsdirhash_mtx) 98#define DIRHASHLIST_UNLOCK() mtx_unlock(&ufsdirhash_mtx) 99#define DIRHASH_BLKALLOC_WAITOK() uma_zalloc(ufsdirhash_zone, M_WAITOK) 100#define DIRHASH_BLKFREE(ptr) uma_zfree(ufsdirhash_zone, (ptr)) 101#define DIRHASH_ASSERT_LOCKED(dh) \ 102 sx_assert(&(dh)->dh_lock, SA_LOCKED) 103 104/* Dirhash list; recently-used entries are near the tail. */ 105static TAILQ_HEAD(, dirhash) ufsdirhash_list; 106 107/* Protects: ufsdirhash_list, `dh_list' field, ufs_dirhashmem. */ 108static struct mtx ufsdirhash_mtx; 109 110/* 111 * Locking: 112 * 113 * The relationship between inode and dirhash is protected either by an 114 * exclusive vnode lock or the vnode interlock where a shared vnode lock 115 * may be used. The dirhash_mtx is acquired after the dirhash lock. To 116 * handle teardown races, code wishing to lock the dirhash for an inode 117 * when using a shared vnode lock must obtain a private reference on the 118 * dirhash while holding the vnode interlock. They can drop it once they 119 * have obtained the dirhash lock and verified that the dirhash wasn't 120 * recycled while they waited for the dirhash lock. 121 * 122 * ufsdirhash_build() acquires a shared lock on the dirhash when it is 123 * successful. This lock is released after a call to ufsdirhash_lookup(). 124 * 125 * Functions requiring exclusive access use ufsdirhash_acquire() which may 126 * free a dirhash structure that was recycled by ufsdirhash_recycle(). 127 * 128 * The dirhash lock may be held across io operations. 129 */ 130 131static void 132ufsdirhash_hold(struct dirhash *dh) 133{ 134 135 refcount_acquire(&dh->dh_refcount); 136} 137 138static void 139ufsdirhash_drop(struct dirhash *dh) 140{ 141 142 if (refcount_release(&dh->dh_refcount)) { 143 sx_destroy(&dh->dh_lock); 144 free(dh, M_DIRHASH); 145 } 146} 147 148/* 149 * Release the lock on a dirhash. 150 */ 151static void 152ufsdirhash_release(struct dirhash *dh) 153{ 154 155 sx_unlock(&dh->dh_lock); 156} 157 158/* 159 * Either acquire an existing hash locked shared or create a new hash and 160 * return it exclusively locked. May return NULL if the allocation fails. 161 * 162 * The vnode interlock is used to protect the i_dirhash pointer from 163 * simultaneous access while only a shared vnode lock is held. 164 */ 165static struct dirhash * 166ufsdirhash_create(struct inode *ip) 167{ 168 struct dirhash *ndh; 169 struct dirhash *dh; 170 struct vnode *vp; 171 int error; 172 173 error = 0; 174 ndh = dh = NULL; 175 vp = ip->i_vnode; 176 for (;;) { 177 /* Racy check for i_dirhash to prefetch an dirhash structure. */ 178 if (ip->i_dirhash == NULL && ndh == NULL) { 179 ndh = malloc(sizeof *dh, M_DIRHASH, 180 M_NOWAIT | M_ZERO); 181 if (ndh == NULL) 182 return (NULL); 183 refcount_init(&ndh->dh_refcount, 1); 184 185 /* 186 * The DUPOK is to prevent warnings from the 187 * sx_slock() a few lines down which is safe 188 * since the duplicate lock in that case is 189 * the one for this dirhash we are creating 190 * now which has no external references until 191 * after this function returns. 192 */ 193 sx_init_flags(&ndh->dh_lock, "dirhash", SX_DUPOK); 194 sx_xlock(&ndh->dh_lock); 195 } 196 /* 197 * Check i_dirhash. If it's NULL just try to use a 198 * preallocated structure. If none exists loop and try again. 199 */ 200 VI_LOCK(vp); 201 dh = ip->i_dirhash; 202 if (dh == NULL) { 203 ip->i_dirhash = ndh; 204 VI_UNLOCK(vp); 205 if (ndh == NULL) 206 continue; 207 return (ndh); 208 } 209 ufsdirhash_hold(dh); 210 VI_UNLOCK(vp); 211 212 /* Acquire a shared lock on existing hashes. */ 213 sx_slock(&dh->dh_lock); 214 215 /* The hash could've been recycled while we were waiting. */ 216 VI_LOCK(vp); 217 if (ip->i_dirhash != dh) { 218 VI_UNLOCK(vp); 219 ufsdirhash_release(dh); 220 ufsdirhash_drop(dh); 221 continue; 222 } 223 VI_UNLOCK(vp); 224 ufsdirhash_drop(dh); 225 226 /* If the hash is still valid we've succeeded. */ 227 if (dh->dh_hash != NULL) 228 break; 229 /* 230 * If the hash is NULL it has been recycled. Try to upgrade 231 * so we can recreate it. If we fail the upgrade, drop our 232 * lock and try again. 233 */ 234 if (sx_try_upgrade(&dh->dh_lock)) 235 break; 236 sx_sunlock(&dh->dh_lock); 237 } 238 /* Free the preallocated structure if it was not necessary. */ 239 if (ndh) { 240 ufsdirhash_release(ndh); 241 ufsdirhash_drop(ndh); 242 } 243 return (dh); 244} 245 246/* 247 * Acquire an exclusive lock on an existing hash. Requires an exclusive 248 * vnode lock to protect the i_dirhash pointer. hashes that have been 249 * recycled are reclaimed here and NULL is returned. 250 */ 251static struct dirhash * 252ufsdirhash_acquire(struct inode *ip) 253{ 254 struct dirhash *dh; 255 struct vnode *vp; 256 257 ASSERT_VOP_ELOCKED(ip->i_vnode, __FUNCTION__); 258 259 vp = ip->i_vnode; 260 dh = ip->i_dirhash; 261 if (dh == NULL) 262 return (NULL); 263 sx_xlock(&dh->dh_lock); 264 if (dh->dh_hash != NULL) 265 return (dh); 266 ufsdirhash_free_locked(ip); 267 return (NULL); 268} 269 270/* 271 * Acquire exclusively and free the hash pointed to by ip. Works with a 272 * shared or exclusive vnode lock. 273 */ 274void 275ufsdirhash_free(struct inode *ip) 276{ 277 struct dirhash *dh; 278 struct vnode *vp; 279 280 vp = ip->i_vnode; 281 for (;;) { 282 /* Grab a reference on this inode's dirhash if it has one. */ 283 VI_LOCK(vp); 284 dh = ip->i_dirhash; 285 if (dh == NULL) { 286 VI_UNLOCK(vp); 287 return; 288 } 289 ufsdirhash_hold(dh); 290 VI_UNLOCK(vp); 291 292 /* Exclusively lock the dirhash. */ 293 sx_xlock(&dh->dh_lock); 294 295 /* If this dirhash still belongs to this inode, then free it. */ 296 VI_LOCK(vp); 297 if (ip->i_dirhash == dh) { 298 VI_UNLOCK(vp); 299 ufsdirhash_drop(dh); 300 break; 301 } 302 VI_UNLOCK(vp); 303 304 /* 305 * This inode's dirhash has changed while we were 306 * waiting for the dirhash lock, so try again. 307 */ 308 ufsdirhash_release(dh); 309 ufsdirhash_drop(dh); 310 } 311 ufsdirhash_free_locked(ip); 312} 313 314/* 315 * Attempt to build up a hash table for the directory contents in 316 * inode 'ip'. Returns 0 on success, or -1 of the operation failed. 317 */ 318int 319ufsdirhash_build(struct inode *ip) 320{ 321 struct dirhash *dh; 322 struct buf *bp = NULL; 323 struct direct *ep; 324 struct vnode *vp; 325 doff_t bmask, pos; 326 int dirblocks, i, j, memreqd, nblocks, narrays, nslots, slot; 327 328 /* Take care of a decreased sysctl value. */ 329 while (ufs_dirhashmem > ufs_dirhashmaxmem) 330 if (ufsdirhash_recycle(0) != 0) 331 return (-1); 332 333 /* Check if we can/should use dirhash. */ 334 if (ip->i_size < ufs_mindirhashsize || OFSFMT(ip->i_vnode) || 335 ip->i_effnlink == 0) { 336 if (ip->i_dirhash) 337 ufsdirhash_free(ip); 338 return (-1); 339 } 340 dh = ufsdirhash_create(ip); 341 if (dh == NULL) 342 return (-1); 343 if (dh->dh_hash != NULL) 344 return (0); 345 346 vp = ip->i_vnode; 347 /* Allocate 50% more entries than this dir size could ever need. */ 348 KASSERT(ip->i_size >= DIRBLKSIZ, ("ufsdirhash_build size")); 349 nslots = ip->i_size / DIRECTSIZ(1); 350 nslots = (nslots * 3 + 1) / 2; 351 narrays = howmany(nslots, DH_NBLKOFF); 352 nslots = narrays * DH_NBLKOFF; 353 dirblocks = howmany(ip->i_size, DIRBLKSIZ); 354 nblocks = (dirblocks * 3 + 1) / 2; 355 memreqd = sizeof(*dh) + narrays * sizeof(*dh->dh_hash) + 356 narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) + 357 nblocks * sizeof(*dh->dh_blkfree); 358 DIRHASHLIST_LOCK(); 359 if (memreqd + ufs_dirhashmem > ufs_dirhashmaxmem) { 360 DIRHASHLIST_UNLOCK(); 361 if (memreqd > ufs_dirhashmaxmem / 2) 362 goto fail; 363 /* Try to free some space. */ 364 if (ufsdirhash_recycle(memreqd) != 0) 365 goto fail; 366 /* Enough was freed, and list has been locked. */ 367 } 368 ufs_dirhashmem += memreqd; 369 DIRHASHLIST_UNLOCK(); 370 371 /* Initialise the hash table and block statistics. */ 372 dh->dh_memreq = memreqd; 373 dh->dh_narrays = narrays; 374 dh->dh_hlen = nslots; 375 dh->dh_nblk = nblocks; 376 dh->dh_dirblks = dirblocks; 377 for (i = 0; i < DH_NFSTATS; i++) 378 dh->dh_firstfree[i] = -1; 379 dh->dh_firstfree[DH_NFSTATS] = 0; 380 dh->dh_hused = 0; 381 dh->dh_seqopt = 0; 382 dh->dh_seqoff = 0; 383 dh->dh_score = DH_SCOREINIT; 384 385 /* 386 * Use non-blocking mallocs so that we will revert to a linear 387 * lookup on failure rather than potentially blocking forever. 388 */ 389 dh->dh_hash = malloc(narrays * sizeof(dh->dh_hash[0]), 390 M_DIRHASH, M_NOWAIT | M_ZERO); 391 if (dh->dh_hash == NULL) 392 goto fail; 393 dh->dh_blkfree = malloc(nblocks * sizeof(dh->dh_blkfree[0]), 394 M_DIRHASH, M_NOWAIT); 395 if (dh->dh_blkfree == NULL) 396 goto fail; 397 for (i = 0; i < narrays; i++) { 398 if ((dh->dh_hash[i] = DIRHASH_BLKALLOC_WAITOK()) == NULL) 399 goto fail; 400 for (j = 0; j < DH_NBLKOFF; j++) 401 dh->dh_hash[i][j] = DIRHASH_EMPTY; 402 } 403 for (i = 0; i < dirblocks; i++) 404 dh->dh_blkfree[i] = DIRBLKSIZ / DIRALIGN; 405 bmask = VFSTOUFS(vp->v_mount)->um_mountp->mnt_stat.f_iosize - 1; 406 pos = 0; 407 while (pos < ip->i_size) { 408 /* If necessary, get the next directory block. */ 409 if ((pos & bmask) == 0) { 410 if (bp != NULL) 411 brelse(bp); 412 if (UFS_BLKATOFF(vp, (off_t)pos, NULL, &bp) != 0) 413 goto fail; 414 } 415 416 /* Add this entry to the hash. */ 417 ep = (struct direct *)((char *)bp->b_data + (pos & bmask)); 418 if (ep->d_reclen == 0 || ep->d_reclen > 419 DIRBLKSIZ - (pos & (DIRBLKSIZ - 1))) { 420 /* Corrupted directory. */ 421 brelse(bp); 422 goto fail; 423 } 424 if (ep->d_ino != 0) { 425 /* Add the entry (simplified ufsdirhash_add). */ 426 slot = ufsdirhash_hash(dh, ep->d_name, ep->d_namlen); 427 while (DH_ENTRY(dh, slot) != DIRHASH_EMPTY) 428 slot = WRAPINCR(slot, dh->dh_hlen); 429 dh->dh_hused++; 430 DH_ENTRY(dh, slot) = pos; 431 ufsdirhash_adjfree(dh, pos, -DIRSIZ(0, ep)); 432 } 433 pos += ep->d_reclen; 434 } 435 436 if (bp != NULL) 437 brelse(bp); 438 DIRHASHLIST_LOCK(); 439 TAILQ_INSERT_TAIL(&ufsdirhash_list, dh, dh_list); 440 dh->dh_onlist = 1; 441 DIRHASHLIST_UNLOCK(); 442 sx_downgrade(&dh->dh_lock); 443 return (0); 444 445fail: 446 ufsdirhash_free_locked(ip); 447 return (-1); 448} 449 450/* 451 * Free any hash table associated with inode 'ip'. 452 */ 453static void 454ufsdirhash_free_locked(struct inode *ip) 455{ 456 struct dirhash *dh; 457 struct vnode *vp; 458 int i; 459 460 DIRHASH_ASSERT_LOCKED(ip->i_dirhash); 461 462 /* 463 * Clear the pointer in the inode to prevent new threads from 464 * finding the dead structure. 465 */ 466 vp = ip->i_vnode; 467 VI_LOCK(vp); 468 dh = ip->i_dirhash; 469 ip->i_dirhash = NULL; 470 VI_UNLOCK(vp); 471 472 /* 473 * Remove the hash from the list since we are going to free its 474 * memory. 475 */ 476 DIRHASHLIST_LOCK(); 477 if (dh->dh_onlist) 478 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 479 ufs_dirhashmem -= dh->dh_memreq; 480 DIRHASHLIST_UNLOCK(); 481 482 /* 483 * At this point, any waiters for the lock should hold their 484 * own reference on the dirhash structure. They will drop 485 * that reference once they grab the vnode interlock and see 486 * that ip->i_dirhash is NULL. 487 */ 488 sx_xunlock(&dh->dh_lock); 489 490 /* 491 * Handle partially recycled as well as fully constructed hashes. 492 */ 493 if (dh->dh_hash != NULL) { 494 for (i = 0; i < dh->dh_narrays; i++) 495 if (dh->dh_hash[i] != NULL) 496 DIRHASH_BLKFREE(dh->dh_hash[i]); 497 free(dh->dh_hash, M_DIRHASH); 498 if (dh->dh_blkfree != NULL) 499 free(dh->dh_blkfree, M_DIRHASH); 500 } 501 502 /* 503 * Drop the inode's reference to the data structure. 504 */ 505 ufsdirhash_drop(dh); 506} 507 508/* 509 * Find the offset of the specified name within the given inode. 510 * Returns 0 on success, ENOENT if the entry does not exist, or 511 * EJUSTRETURN if the caller should revert to a linear search. 512 * 513 * If successful, the directory offset is stored in *offp, and a 514 * pointer to a struct buf containing the entry is stored in *bpp. If 515 * prevoffp is non-NULL, the offset of the previous entry within 516 * the DIRBLKSIZ-sized block is stored in *prevoffp (if the entry 517 * is the first in a block, the start of the block is used). 518 * 519 * Must be called with the hash locked. Returns with the hash unlocked. 520 */ 521int 522ufsdirhash_lookup(struct inode *ip, char *name, int namelen, doff_t *offp, 523 struct buf **bpp, doff_t *prevoffp) 524{ 525 struct dirhash *dh, *dh_next; 526 struct direct *dp; 527 struct vnode *vp; 528 struct buf *bp; 529 doff_t blkoff, bmask, offset, prevoff; 530 int i, slot; 531 int error; 532 533 dh = ip->i_dirhash; 534 KASSERT(dh != NULL && dh->dh_hash != NULL, 535 ("ufsdirhash_lookup: Invalid dirhash %p\n", dh)); 536 DIRHASH_ASSERT_LOCKED(dh); 537 /* 538 * Move this dirhash towards the end of the list if it has a 539 * score higher than the next entry, and acquire the dh_lock. 540 */ 541 DIRHASHLIST_LOCK(); 542 if (TAILQ_NEXT(dh, dh_list) != NULL) { 543 /* 544 * If the new score will be greater than that of the next 545 * entry, then move this entry past it. With both mutexes 546 * held, dh_next won't go away, but its dh_score could 547 * change; that's not important since it is just a hint. 548 */ 549 if ((dh_next = TAILQ_NEXT(dh, dh_list)) != NULL && 550 dh->dh_score >= dh_next->dh_score) { 551 KASSERT(dh->dh_onlist, ("dirhash: not on list")); 552 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 553 TAILQ_INSERT_AFTER(&ufsdirhash_list, dh_next, dh, 554 dh_list); 555 } 556 } 557 /* Update the score. */ 558 if (dh->dh_score < DH_SCOREMAX) 559 dh->dh_score++; 560 DIRHASHLIST_UNLOCK(); 561 562 vp = ip->i_vnode; 563 bmask = VFSTOUFS(vp->v_mount)->um_mountp->mnt_stat.f_iosize - 1; 564 blkoff = -1; 565 bp = NULL; 566restart: 567 slot = ufsdirhash_hash(dh, name, namelen); 568 569 if (dh->dh_seqopt) { 570 /* 571 * Sequential access optimisation. dh_seqoff contains the 572 * offset of the directory entry immediately following 573 * the last entry that was looked up. Check if this offset 574 * appears in the hash chain for the name we are looking for. 575 */ 576 for (i = slot; (offset = DH_ENTRY(dh, i)) != DIRHASH_EMPTY; 577 i = WRAPINCR(i, dh->dh_hlen)) 578 if (offset == dh->dh_seqoff) 579 break; 580 if (offset == dh->dh_seqoff) { 581 /* 582 * We found an entry with the expected offset. This 583 * is probably the entry we want, but if not, the 584 * code below will turn off seqopt and retry. 585 */ 586 slot = i; 587 } else 588 dh->dh_seqopt = 0; 589 } 590 591 for (; (offset = DH_ENTRY(dh, slot)) != DIRHASH_EMPTY; 592 slot = WRAPINCR(slot, dh->dh_hlen)) { 593 if (offset == DIRHASH_DEL) 594 continue; 595 if (offset < 0 || offset >= ip->i_size) 596 panic("ufsdirhash_lookup: bad offset in hash array"); 597 if ((offset & ~bmask) != blkoff) { 598 if (bp != NULL) 599 brelse(bp); 600 blkoff = offset & ~bmask; 601 if (UFS_BLKATOFF(vp, (off_t)blkoff, NULL, &bp) != 0) { 602 error = EJUSTRETURN; 603 goto fail; 604 } 605 } 606 dp = (struct direct *)(bp->b_data + (offset & bmask)); 607 if (dp->d_reclen == 0 || dp->d_reclen > 608 DIRBLKSIZ - (offset & (DIRBLKSIZ - 1))) { 609 /* Corrupted directory. */ 610 error = EJUSTRETURN; 611 goto fail; 612 } 613 if (dp->d_namlen == namelen && 614 bcmp(dp->d_name, name, namelen) == 0) { 615 /* Found. Get the prev offset if needed. */ 616 if (prevoffp != NULL) { 617 if (offset & (DIRBLKSIZ - 1)) { 618 prevoff = ufsdirhash_getprev(dp, 619 offset); 620 if (prevoff == -1) { 621 error = EJUSTRETURN; 622 goto fail; 623 } 624 } else 625 prevoff = offset; 626 *prevoffp = prevoff; 627 } 628 629 /* Check for sequential access, and update offset. */ 630 if (dh->dh_seqopt == 0 && dh->dh_seqoff == offset) 631 dh->dh_seqopt = 1; 632 dh->dh_seqoff = offset + DIRSIZ(0, dp); 633 *bpp = bp; 634 *offp = offset; 635 ufsdirhash_release(dh); 636 return (0); 637 } 638 639 /* 640 * When the name doesn't match in the seqopt case, go back 641 * and search normally. 642 */ 643 if (dh->dh_seqopt) { 644 dh->dh_seqopt = 0; 645 goto restart; 646 } 647 } 648 error = ENOENT; 649fail: 650 ufsdirhash_release(dh); 651 if (bp != NULL) 652 brelse(bp); 653 return (error); 654} 655 656/* 657 * Find a directory block with room for 'slotneeded' bytes. Returns 658 * the offset of the directory entry that begins the free space. 659 * This will either be the offset of an existing entry that has free 660 * space at the end, or the offset of an entry with d_ino == 0 at 661 * the start of a DIRBLKSIZ block. 662 * 663 * To use the space, the caller may need to compact existing entries in 664 * the directory. The total number of bytes in all of the entries involved 665 * in the compaction is stored in *slotsize. In other words, all of 666 * the entries that must be compacted are exactly contained in the 667 * region beginning at the returned offset and spanning *slotsize bytes. 668 * 669 * Returns -1 if no space was found, indicating that the directory 670 * must be extended. 671 */ 672doff_t 673ufsdirhash_findfree(struct inode *ip, int slotneeded, int *slotsize) 674{ 675 struct direct *dp; 676 struct dirhash *dh; 677 struct buf *bp; 678 doff_t pos, slotstart; 679 int dirblock, error, freebytes, i; 680 681 dh = ip->i_dirhash; 682 KASSERT(dh != NULL && dh->dh_hash != NULL, 683 ("ufsdirhash_findfree: Invalid dirhash %p\n", dh)); 684 DIRHASH_ASSERT_LOCKED(dh); 685 686 /* Find a directory block with the desired free space. */ 687 dirblock = -1; 688 for (i = howmany(slotneeded, DIRALIGN); i <= DH_NFSTATS; i++) 689 if ((dirblock = dh->dh_firstfree[i]) != -1) 690 break; 691 if (dirblock == -1) 692 return (-1); 693 694 KASSERT(dirblock < dh->dh_nblk && 695 dh->dh_blkfree[dirblock] >= howmany(slotneeded, DIRALIGN), 696 ("ufsdirhash_findfree: bad stats")); 697 pos = dirblock * DIRBLKSIZ; 698 error = UFS_BLKATOFF(ip->i_vnode, (off_t)pos, (char **)&dp, &bp); 699 if (error) 700 return (-1); 701 702 /* Find the first entry with free space. */ 703 for (i = 0; i < DIRBLKSIZ; ) { 704 if (dp->d_reclen == 0) { 705 brelse(bp); 706 return (-1); 707 } 708 if (dp->d_ino == 0 || dp->d_reclen > DIRSIZ(0, dp)) 709 break; 710 i += dp->d_reclen; 711 dp = (struct direct *)((char *)dp + dp->d_reclen); 712 } 713 if (i > DIRBLKSIZ) { 714 brelse(bp); 715 return (-1); 716 } 717 slotstart = pos + i; 718 719 /* Find the range of entries needed to get enough space */ 720 freebytes = 0; 721 while (i < DIRBLKSIZ && freebytes < slotneeded) { 722 freebytes += dp->d_reclen; 723 if (dp->d_ino != 0) 724 freebytes -= DIRSIZ(0, dp); 725 if (dp->d_reclen == 0) { 726 brelse(bp); 727 return (-1); 728 } 729 i += dp->d_reclen; 730 dp = (struct direct *)((char *)dp + dp->d_reclen); 731 } 732 if (i > DIRBLKSIZ) { 733 brelse(bp); 734 return (-1); 735 } 736 if (freebytes < slotneeded) 737 panic("ufsdirhash_findfree: free mismatch"); 738 brelse(bp); 739 *slotsize = pos + i - slotstart; 740 return (slotstart); 741} 742 743/* 744 * Return the start of the unused space at the end of a directory, or 745 * -1 if there are no trailing unused blocks. 746 */ 747doff_t 748ufsdirhash_enduseful(struct inode *ip) 749{ 750 751 struct dirhash *dh; 752 int i; 753 754 dh = ip->i_dirhash; 755 DIRHASH_ASSERT_LOCKED(dh); 756 KASSERT(dh != NULL && dh->dh_hash != NULL, 757 ("ufsdirhash_enduseful: Invalid dirhash %p\n", dh)); 758 759 if (dh->dh_blkfree[dh->dh_dirblks - 1] != DIRBLKSIZ / DIRALIGN) 760 return (-1); 761 762 for (i = dh->dh_dirblks - 1; i >= 0; i--) 763 if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN) 764 break; 765 766 return ((doff_t)(i + 1) * DIRBLKSIZ); 767} 768 769/* 770 * Insert information into the hash about a new directory entry. dirp 771 * points to a struct direct containing the entry, and offset specifies 772 * the offset of this entry. 773 */ 774void 775ufsdirhash_add(struct inode *ip, struct direct *dirp, doff_t offset) 776{ 777 struct dirhash *dh; 778 int slot; 779 780 if ((dh = ufsdirhash_acquire(ip)) == NULL) 781 return; 782 783 KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ, 784 ("ufsdirhash_add: bad offset")); 785 /* 786 * Normal hash usage is < 66%. If the usage gets too high then 787 * remove the hash entirely and let it be rebuilt later. 788 */ 789 if (dh->dh_hused >= (dh->dh_hlen * 3) / 4) { 790 ufsdirhash_free_locked(ip); 791 return; 792 } 793 794 /* Find a free hash slot (empty or deleted), and add the entry. */ 795 slot = ufsdirhash_hash(dh, dirp->d_name, dirp->d_namlen); 796 while (DH_ENTRY(dh, slot) >= 0) 797 slot = WRAPINCR(slot, dh->dh_hlen); 798 if (DH_ENTRY(dh, slot) == DIRHASH_EMPTY) 799 dh->dh_hused++; 800 DH_ENTRY(dh, slot) = offset; 801 802 /* Update the per-block summary info. */ 803 ufsdirhash_adjfree(dh, offset, -DIRSIZ(0, dirp)); 804 ufsdirhash_release(dh); 805} 806 807/* 808 * Remove the specified directory entry from the hash. The entry to remove 809 * is defined by the name in `dirp', which must exist at the specified 810 * `offset' within the directory. 811 */ 812void 813ufsdirhash_remove(struct inode *ip, struct direct *dirp, doff_t offset) 814{ 815 struct dirhash *dh; 816 int slot; 817 818 if ((dh = ufsdirhash_acquire(ip)) == NULL) 819 return; 820 821 KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ, 822 ("ufsdirhash_remove: bad offset")); 823 /* Find the entry */ 824 slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, offset); 825 826 /* Remove the hash entry. */ 827 ufsdirhash_delslot(dh, slot); 828 829 /* Update the per-block summary info. */ 830 ufsdirhash_adjfree(dh, offset, DIRSIZ(0, dirp)); 831 ufsdirhash_release(dh); 832} 833 834/* 835 * Change the offset associated with a directory entry in the hash. Used 836 * when compacting directory blocks. 837 */ 838void 839ufsdirhash_move(struct inode *ip, struct direct *dirp, doff_t oldoff, 840 doff_t newoff) 841{ 842 struct dirhash *dh; 843 int slot; 844 845 if ((dh = ufsdirhash_acquire(ip)) == NULL) 846 return; 847 848 KASSERT(oldoff < dh->dh_dirblks * DIRBLKSIZ && 849 newoff < dh->dh_dirblks * DIRBLKSIZ, 850 ("ufsdirhash_move: bad offset")); 851 /* Find the entry, and update the offset. */ 852 slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, oldoff); 853 DH_ENTRY(dh, slot) = newoff; 854 ufsdirhash_release(dh); 855} 856 857/* 858 * Inform dirhash that the directory has grown by one block that 859 * begins at offset (i.e. the new length is offset + DIRBLKSIZ). 860 */ 861void 862ufsdirhash_newblk(struct inode *ip, doff_t offset) 863{ 864 struct dirhash *dh; 865 int block; 866 867 if ((dh = ufsdirhash_acquire(ip)) == NULL) 868 return; 869 870 KASSERT(offset == dh->dh_dirblks * DIRBLKSIZ, 871 ("ufsdirhash_newblk: bad offset")); 872 block = offset / DIRBLKSIZ; 873 if (block >= dh->dh_nblk) { 874 /* Out of space; must rebuild. */ 875 ufsdirhash_free_locked(ip); 876 return; 877 } 878 dh->dh_dirblks = block + 1; 879 880 /* Account for the new free block. */ 881 dh->dh_blkfree[block] = DIRBLKSIZ / DIRALIGN; 882 if (dh->dh_firstfree[DH_NFSTATS] == -1) 883 dh->dh_firstfree[DH_NFSTATS] = block; 884 ufsdirhash_release(dh); 885} 886 887/* 888 * Inform dirhash that the directory is being truncated. 889 */ 890void 891ufsdirhash_dirtrunc(struct inode *ip, doff_t offset) 892{ 893 struct dirhash *dh; 894 int block, i; 895 896 if ((dh = ufsdirhash_acquire(ip)) == NULL) 897 return; 898 899 KASSERT(offset <= dh->dh_dirblks * DIRBLKSIZ, 900 ("ufsdirhash_dirtrunc: bad offset")); 901 block = howmany(offset, DIRBLKSIZ); 902 /* 903 * If the directory shrinks to less than 1/8 of dh_nblk blocks 904 * (about 20% of its original size due to the 50% extra added in 905 * ufsdirhash_build) then free it, and let the caller rebuild 906 * if necessary. 907 */ 908 if (block < dh->dh_nblk / 8 && dh->dh_narrays > 1) { 909 ufsdirhash_free_locked(ip); 910 return; 911 } 912 913 /* 914 * Remove any `first free' information pertaining to the 915 * truncated blocks. All blocks we're removing should be 916 * completely unused. 917 */ 918 if (dh->dh_firstfree[DH_NFSTATS] >= block) 919 dh->dh_firstfree[DH_NFSTATS] = -1; 920 for (i = block; i < dh->dh_dirblks; i++) 921 if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN) 922 panic("ufsdirhash_dirtrunc: blocks in use"); 923 for (i = 0; i < DH_NFSTATS; i++) 924 if (dh->dh_firstfree[i] >= block) 925 panic("ufsdirhash_dirtrunc: first free corrupt"); 926 dh->dh_dirblks = block; 927 ufsdirhash_release(dh); 928} 929 930/* 931 * Debugging function to check that the dirhash information about 932 * a directory block matches its actual contents. Panics if a mismatch 933 * is detected. 934 * 935 * On entry, `buf' should point to the start of an in-core 936 * DIRBLKSIZ-sized directory block, and `offset' should contain the 937 * offset from the start of the directory of that block. 938 */ 939void 940ufsdirhash_checkblock(struct inode *ip, char *buf, doff_t offset) 941{ 942 struct dirhash *dh; 943 struct direct *dp; 944 int block, ffslot, i, nfree; 945 946 if (!ufs_dirhashcheck) 947 return; 948 if ((dh = ufsdirhash_acquire(ip)) == NULL) 949 return; 950 951 block = offset / DIRBLKSIZ; 952 if ((offset & (DIRBLKSIZ - 1)) != 0 || block >= dh->dh_dirblks) 953 panic("ufsdirhash_checkblock: bad offset"); 954 955 nfree = 0; 956 for (i = 0; i < DIRBLKSIZ; i += dp->d_reclen) { 957 dp = (struct direct *)(buf + i); 958 if (dp->d_reclen == 0 || i + dp->d_reclen > DIRBLKSIZ) 959 panic("ufsdirhash_checkblock: bad dir"); 960 961 if (dp->d_ino == 0) { 962#if 0 963 /* 964 * XXX entries with d_ino == 0 should only occur 965 * at the start of a DIRBLKSIZ block. However the 966 * ufs code is tolerant of such entries at other 967 * offsets, and fsck does not fix them. 968 */ 969 if (i != 0) 970 panic("ufsdirhash_checkblock: bad dir inode"); 971#endif 972 nfree += dp->d_reclen; 973 continue; 974 } 975 976 /* Check that the entry exists (will panic if it doesn't). */ 977 ufsdirhash_findslot(dh, dp->d_name, dp->d_namlen, offset + i); 978 979 nfree += dp->d_reclen - DIRSIZ(0, dp); 980 } 981 if (i != DIRBLKSIZ) 982 panic("ufsdirhash_checkblock: bad dir end"); 983 984 if (dh->dh_blkfree[block] * DIRALIGN != nfree) 985 panic("ufsdirhash_checkblock: bad free count"); 986 987 ffslot = BLKFREE2IDX(nfree / DIRALIGN); 988 for (i = 0; i <= DH_NFSTATS; i++) 989 if (dh->dh_firstfree[i] == block && i != ffslot) 990 panic("ufsdirhash_checkblock: bad first-free"); 991 if (dh->dh_firstfree[ffslot] == -1) 992 panic("ufsdirhash_checkblock: missing first-free entry"); 993 ufsdirhash_release(dh); 994} 995 996/* 997 * Hash the specified filename into a dirhash slot. 998 */ 999static int 1000ufsdirhash_hash(struct dirhash *dh, char *name, int namelen) 1001{ 1002 u_int32_t hash; 1003 1004 /* 1005 * We hash the name and then some other bit of data that is 1006 * invariant over the dirhash's lifetime. Otherwise names 1007 * differing only in the last byte are placed close to one 1008 * another in the table, which is bad for linear probing. 1009 */ 1010 hash = fnv_32_buf(name, namelen, FNV1_32_INIT); 1011 hash = fnv_32_buf(&dh, sizeof(dh), hash); 1012 return (hash % dh->dh_hlen); 1013} 1014 1015/* 1016 * Adjust the number of free bytes in the block containing `offset' 1017 * by the value specified by `diff'. 1018 * 1019 * The caller must ensure we have exclusive access to `dh'; normally 1020 * that means that dh_lock should be held, but this is also called 1021 * from ufsdirhash_build() where exclusive access can be assumed. 1022 */ 1023static void 1024ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff) 1025{ 1026 int block, i, nfidx, ofidx; 1027 1028 /* Update the per-block summary info. */ 1029 block = offset / DIRBLKSIZ; 1030 KASSERT(block < dh->dh_nblk && block < dh->dh_dirblks, 1031 ("dirhash bad offset")); 1032 ofidx = BLKFREE2IDX(dh->dh_blkfree[block]); 1033 dh->dh_blkfree[block] = (int)dh->dh_blkfree[block] + (diff / DIRALIGN); 1034 nfidx = BLKFREE2IDX(dh->dh_blkfree[block]); 1035 1036 /* Update the `first free' list if necessary. */ 1037 if (ofidx != nfidx) { 1038 /* If removing, scan forward for the next block. */ 1039 if (dh->dh_firstfree[ofidx] == block) { 1040 for (i = block + 1; i < dh->dh_dirblks; i++) 1041 if (BLKFREE2IDX(dh->dh_blkfree[i]) == ofidx) 1042 break; 1043 dh->dh_firstfree[ofidx] = (i < dh->dh_dirblks) ? i : -1; 1044 } 1045 1046 /* Make this the new `first free' if necessary */ 1047 if (dh->dh_firstfree[nfidx] > block || 1048 dh->dh_firstfree[nfidx] == -1) 1049 dh->dh_firstfree[nfidx] = block; 1050 } 1051} 1052 1053/* 1054 * Find the specified name which should have the specified offset. 1055 * Returns a slot number, and panics on failure. 1056 * 1057 * `dh' must be locked on entry and remains so on return. 1058 */ 1059static int 1060ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, doff_t offset) 1061{ 1062 int slot; 1063 1064 DIRHASH_ASSERT_LOCKED(dh); 1065 1066 /* Find the entry. */ 1067 KASSERT(dh->dh_hused < dh->dh_hlen, ("dirhash find full")); 1068 slot = ufsdirhash_hash(dh, name, namelen); 1069 while (DH_ENTRY(dh, slot) != offset && 1070 DH_ENTRY(dh, slot) != DIRHASH_EMPTY) 1071 slot = WRAPINCR(slot, dh->dh_hlen); 1072 if (DH_ENTRY(dh, slot) != offset) 1073 panic("ufsdirhash_findslot: '%.*s' not found", namelen, name); 1074 1075 return (slot); 1076} 1077 1078/* 1079 * Remove the entry corresponding to the specified slot from the hash array. 1080 * 1081 * `dh' must be locked on entry and remains so on return. 1082 */ 1083static void 1084ufsdirhash_delslot(struct dirhash *dh, int slot) 1085{ 1086 int i; 1087 1088 DIRHASH_ASSERT_LOCKED(dh); 1089 1090 /* Mark the entry as deleted. */ 1091 DH_ENTRY(dh, slot) = DIRHASH_DEL; 1092 1093 /* If this is the end of a chain of DIRHASH_DEL slots, remove them. */ 1094 for (i = slot; DH_ENTRY(dh, i) == DIRHASH_DEL; ) 1095 i = WRAPINCR(i, dh->dh_hlen); 1096 if (DH_ENTRY(dh, i) == DIRHASH_EMPTY) { 1097 i = WRAPDECR(i, dh->dh_hlen); 1098 while (DH_ENTRY(dh, i) == DIRHASH_DEL) { 1099 DH_ENTRY(dh, i) = DIRHASH_EMPTY; 1100 dh->dh_hused--; 1101 i = WRAPDECR(i, dh->dh_hlen); 1102 } 1103 KASSERT(dh->dh_hused >= 0, ("ufsdirhash_delslot neg hlen")); 1104 } 1105} 1106 1107/* 1108 * Given a directory entry and its offset, find the offset of the 1109 * previous entry in the same DIRBLKSIZ-sized block. Returns an 1110 * offset, or -1 if there is no previous entry in the block or some 1111 * other problem occurred. 1112 */ 1113static doff_t 1114ufsdirhash_getprev(struct direct *dirp, doff_t offset) 1115{ 1116 struct direct *dp; 1117 char *blkbuf; 1118 doff_t blkoff, prevoff; 1119 int entrypos, i; 1120 1121 blkoff = offset & ~(DIRBLKSIZ - 1); /* offset of start of block */ 1122 entrypos = offset & (DIRBLKSIZ - 1); /* entry relative to block */ 1123 blkbuf = (char *)dirp - entrypos; 1124 prevoff = blkoff; 1125 1126 /* If `offset' is the start of a block, there is no previous entry. */ 1127 if (entrypos == 0) 1128 return (-1); 1129 1130 /* Scan from the start of the block until we get to the entry. */ 1131 for (i = 0; i < entrypos; i += dp->d_reclen) { 1132 dp = (struct direct *)(blkbuf + i); 1133 if (dp->d_reclen == 0 || i + dp->d_reclen > entrypos) 1134 return (-1); /* Corrupted directory. */ 1135 prevoff = blkoff + i; 1136 } 1137 return (prevoff); 1138} 1139 1140/* 1141 * Try to free up `wanted' bytes by stealing memory from existing 1142 * dirhashes. Returns zero with list locked if successful. 1143 */ 1144static int 1145ufsdirhash_recycle(int wanted) 1146{ 1147 struct dirhash *dh; 1148 doff_t **hash; 1149 u_int8_t *blkfree; 1150 int i, mem, narrays; 1151 1152 DIRHASHLIST_LOCK(); 1153 dh = TAILQ_FIRST(&ufsdirhash_list); 1154 while (wanted + ufs_dirhashmem > ufs_dirhashmaxmem) { 1155 /* Decrement the score; only recycle if it becomes zero. */ 1156 if (dh == NULL || --dh->dh_score > 0) { 1157 DIRHASHLIST_UNLOCK(); 1158 return (-1); 1159 } 1160 /* 1161 * If we can't lock it it's in use and we don't want to 1162 * recycle it anyway. 1163 */ 1164 if (!sx_try_xlock(&dh->dh_lock)) { 1165 dh = TAILQ_NEXT(dh, dh_list); 1166 continue; 1167 } 1168 KASSERT(dh->dh_hash != NULL, ("dirhash: NULL hash on list")); 1169 1170 /* Remove it from the list and detach its memory. */ 1171 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 1172 dh->dh_onlist = 0; 1173 hash = dh->dh_hash; 1174 dh->dh_hash = NULL; 1175 blkfree = dh->dh_blkfree; 1176 dh->dh_blkfree = NULL; 1177 narrays = dh->dh_narrays; 1178 mem = dh->dh_memreq; 1179 dh->dh_memreq = 0; 1180 1181 /* Unlock everything, free the detached memory. */ 1182 ufsdirhash_release(dh); 1183 DIRHASHLIST_UNLOCK(); 1184 for (i = 0; i < narrays; i++) 1185 DIRHASH_BLKFREE(hash[i]); 1186 free(hash, M_DIRHASH); 1187 free(blkfree, M_DIRHASH); 1188 1189 /* Account for the returned memory, and repeat if necessary. */ 1190 DIRHASHLIST_LOCK(); 1191 ufs_dirhashmem -= mem; 1192 dh = TAILQ_FIRST(&ufsdirhash_list); 1193 } 1194 /* Success; return with list locked. */ 1195 return (0); 1196} 1197 1198 1199void 1200ufsdirhash_init() 1201{ 1202 ufsdirhash_zone = uma_zcreate("DIRHASH", DH_NBLKOFF * sizeof(doff_t), 1203 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 1204 mtx_init(&ufsdirhash_mtx, "dirhash list", NULL, MTX_DEF); 1205 TAILQ_INIT(&ufsdirhash_list); 1206} 1207 1208void 1209ufsdirhash_uninit() 1210{ 1211 KASSERT(TAILQ_EMPTY(&ufsdirhash_list), ("ufsdirhash_uninit")); 1212 uma_zdestroy(ufsdirhash_zone); 1213 mtx_destroy(&ufsdirhash_mtx); 1214} 1215 1216#endif /* UFS_DIRHASH */ 1217