ufs_dirhash.c revision 178110
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 178110 2008-04-11 09:48:12Z jeff $"); 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/lockmgr.h> 42#include <sys/mutex.h> 43#include <sys/malloc.h> 44#include <sys/fnv_hash.h> 45#include <sys/proc.h> 46#include <sys/bio.h> 47#include <sys/buf.h> 48#include <sys/vnode.h> 49#include <sys/mount.h> 50#include <sys/sysctl.h> 51#include <vm/uma.h> 52 53#include <ufs/ufs/quota.h> 54#include <ufs/ufs/inode.h> 55#include <ufs/ufs/dir.h> 56#include <ufs/ufs/dirhash.h> 57#include <ufs/ufs/extattr.h> 58#include <ufs/ufs/ufsmount.h> 59#include <ufs/ufs/ufs_extern.h> 60 61#define WRAPINCR(val, limit) (((val) + 1 == (limit)) ? 0 : ((val) + 1)) 62#define WRAPDECR(val, limit) (((val) == 0) ? ((limit) - 1) : ((val) - 1)) 63#define OFSFMT(vp) ((vp)->v_mount->mnt_maxsymlinklen <= 0) 64#define BLKFREE2IDX(n) ((n) > DH_NFSTATS ? DH_NFSTATS : (n)) 65 66static MALLOC_DEFINE(M_DIRHASH, "ufs_dirhash", "UFS directory hash tables"); 67 68static SYSCTL_NODE(_vfs, OID_AUTO, ufs, CTLFLAG_RD, 0, "UFS filesystem"); 69 70static int ufs_mindirhashsize = DIRBLKSIZ * 5; 71SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_minsize, CTLFLAG_RW, 72 &ufs_mindirhashsize, 73 0, "minimum directory size in bytes for which to use hashed lookup"); 74static int ufs_dirhashmaxmem = 2 * 1024 * 1024; 75SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_maxmem, CTLFLAG_RW, &ufs_dirhashmaxmem, 76 0, "maximum allowed dirhash memory usage"); 77static int ufs_dirhashmem; 78SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_mem, CTLFLAG_RD, &ufs_dirhashmem, 79 0, "current dirhash memory usage"); 80static int ufs_dirhashcheck = 0; 81SYSCTL_INT(_vfs_ufs, OID_AUTO, dirhash_docheck, CTLFLAG_RW, &ufs_dirhashcheck, 82 0, "enable extra sanity tests"); 83 84 85static int ufsdirhash_hash(struct dirhash *dh, char *name, int namelen); 86static void ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff); 87static void ufsdirhash_delslot(struct dirhash *dh, int slot); 88static int ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, 89 doff_t offset); 90static doff_t ufsdirhash_getprev(struct direct *dp, doff_t offset); 91static int ufsdirhash_recycle(int wanted); 92static void ufsdirhash_free_locked(struct inode *ip); 93 94static uma_zone_t ufsdirhash_zone; 95 96#define DIRHASHLIST_LOCK() mtx_lock(&ufsdirhash_mtx) 97#define DIRHASHLIST_UNLOCK() mtx_unlock(&ufsdirhash_mtx) 98#define DIRHASH_BLKALLOC_WAITOK() uma_zalloc(ufsdirhash_zone, M_WAITOK) 99#define DIRHASH_BLKFREE(ptr) uma_zfree(ufsdirhash_zone, (ptr)) 100#define DIRHASH_ASSERT_LOCKED(dh) \ 101 lockmgr_assert(&(dh)->dh_lock, KA_LOCKED) 102 103/* Dirhash list; recently-used entries are near the tail. */ 104static TAILQ_HEAD(, dirhash) ufsdirhash_list; 105 106/* Protects: ufsdirhash_list, `dh_list' field, ufs_dirhashmem. */ 107static struct mtx ufsdirhash_mtx; 108 109/* 110 * Locking: 111 * 112 * The relationship between inode and dirhash is protected either by an 113 * exclusive vnode lock or the vnode interlock where a shared vnode lock 114 * may be used. The dirhash_mtx is acquired after the dirhash lock. 115 * 116 * ufsdirhash_build() acquires a shared lock on the dirhash when it is 117 * successful. This lock is released after a call to ufsdirhash_lookup(). 118 * 119 * Functions requiring exclusive access use ufsdirhash_acquire() which may 120 * free a dirhash structure that was recycled by ufsdirhash_recycle(). 121 * 122 * The dirhash lock may be held across io operations. 123 */ 124 125/* 126 * Release the lock on a dirhash. 127 */ 128static void 129ufsdirhash_release(struct dirhash *dh) 130{ 131 132 lockmgr(&dh->dh_lock, LK_RELEASE, 0); 133} 134 135/* 136 * Either acquire an existing hash locked shared or create a new hash and 137 * return it exclusively locked. May return NULL if the allocation fails. 138 * 139 * The vnode interlock is used to protect the i_dirhash pointer from 140 * simultaneous access while only a shared vnode lock is held. 141 */ 142static struct dirhash * 143ufsdirhash_create(struct inode *ip) 144{ 145 struct dirhash *ndh; 146 struct dirhash *dh; 147 struct vnode *vp; 148 int error; 149 150 error = 0; 151 ndh = dh = NULL; 152 vp = ip->i_vnode; 153 for (;;) { 154 /* Racy check for i_dirhash to prefetch an dirhash structure. */ 155 if (ip->i_dirhash == NULL && ndh == NULL) { 156 MALLOC(ndh, struct dirhash *, sizeof *dh, M_DIRHASH, 157 M_NOWAIT | M_ZERO); 158 if (ndh == NULL) 159 return (NULL); 160 lockinit(&ndh->dh_lock, PRIBIO, "dirhash", 0, 0); 161 lockmgr(&ndh->dh_lock, LK_EXCLUSIVE, NULL); 162 } 163 /* 164 * Check i_dirhash. If it's NULL just try to use a 165 * preallocated structure. If none exists loop and try again. 166 */ 167 VI_LOCK(vp); 168 dh = ip->i_dirhash; 169 if (dh == NULL) { 170 ip->i_dirhash = ndh; 171 VI_UNLOCK(vp); 172 if (ndh == NULL) 173 continue; 174 return (ndh); 175 } 176 /* Try to acquire shared on existing hashes. */ 177 if (lockmgr(&dh->dh_lock, LK_SHARED | LK_INTERLOCK, 178 VI_MTX(vp))) 179 continue; 180 /* The hash could've been recycled while we were waiting. */ 181 if (ip->i_dirhash != dh) { 182 ufsdirhash_release(dh); 183 continue; 184 } 185 /* If the hash is still valid we've succeeded. */ 186 if (dh->dh_hash != NULL) 187 break; 188 /* 189 * If the hash is NULL it has been recycled. Try to upgrade 190 * so we can recreate it. If we fail the upgrade another 191 * thread must've already exclusively locked it. 192 */ 193 if (lockmgr(&dh->dh_lock, LK_UPGRADE | LK_SLEEPFAIL, NULL) == 0) 194 break; 195 } 196 /* Free the preallocated structure if it was not necessary. */ 197 if (ndh) { 198 lockmgr(&ndh->dh_lock, LK_RELEASE, NULL); 199 lockdestroy(&ndh->dh_lock); 200 FREE(ndh, M_DIRHASH); 201 } 202 return (dh); 203} 204 205/* 206 * Acquire an exclusive lock on an existing hash. Requires an exclusive 207 * vnode lock to protect the i_dirhash pointer. hashes that have been 208 * recycled are reclaimed here and NULL is returned. 209 */ 210static struct dirhash * 211ufsdirhash_acquire(struct inode *ip) 212{ 213 struct dirhash *dh; 214 struct vnode *vp; 215 216 ASSERT_VOP_ELOCKED(ip->i_vnode, __FUNCTION__); 217 218 vp = ip->i_vnode; 219 dh = ip->i_dirhash; 220 if (dh == NULL) 221 return (NULL); 222 lockmgr(&dh->dh_lock, LK_EXCLUSIVE, 0); 223 if (dh->dh_hash != NULL) 224 return (dh); 225 ufsdirhash_free_locked(ip); 226 return (NULL); 227} 228 229/* 230 * Acquire exclusively and free the hash pointed to by ip. Works with a 231 * shared or exclusive vnode lock. 232 */ 233void 234ufsdirhash_free(struct inode *ip) 235{ 236 struct dirhash *dh; 237 struct vnode *vp; 238 239 vp = ip->i_vnode; 240 for (;;) { 241 VI_LOCK(vp); 242 dh = ip->i_dirhash; 243 if (dh == NULL) { 244 VI_UNLOCK(vp); 245 return; 246 } 247 if (lockmgr(&dh->dh_lock, LK_EXCLUSIVE | LK_INTERLOCK, 248 VI_MTX(vp))) 249 continue; 250 if (ip->i_dirhash == dh) 251 break; 252 ufsdirhash_release(dh); 253 } 254 ufsdirhash_free_locked(ip); 255} 256 257/* 258 * Attempt to build up a hash table for the directory contents in 259 * inode 'ip'. Returns 0 on success, or -1 of the operation failed. 260 */ 261int 262ufsdirhash_build(struct inode *ip) 263{ 264 struct dirhash *dh; 265 struct buf *bp = NULL; 266 struct direct *ep; 267 struct vnode *vp; 268 doff_t bmask, pos; 269 int dirblocks, i, j, memreqd, nblocks, narrays, nslots, slot; 270 271 /* Take care of a decreased sysctl value. */ 272 while (ufs_dirhashmem > ufs_dirhashmaxmem) 273 if (ufsdirhash_recycle(0) != 0) 274 return (-1); 275 276 /* Check if we can/should use dirhash. */ 277 if (ip->i_size < ufs_mindirhashsize || OFSFMT(ip->i_vnode) || 278 ip->i_effnlink == 0) { 279 if (ip->i_dirhash) 280 ufsdirhash_free(ip); 281 return (-1); 282 } 283 dh = ufsdirhash_create(ip); 284 if (dh == NULL) 285 return (-1); 286 if (dh->dh_hash != NULL) 287 return (0); 288 289 vp = ip->i_vnode; 290 /* Allocate 50% more entries than this dir size could ever need. */ 291 KASSERT(ip->i_size >= DIRBLKSIZ, ("ufsdirhash_build size")); 292 nslots = ip->i_size / DIRECTSIZ(1); 293 nslots = (nslots * 3 + 1) / 2; 294 narrays = howmany(nslots, DH_NBLKOFF); 295 nslots = narrays * DH_NBLKOFF; 296 dirblocks = howmany(ip->i_size, DIRBLKSIZ); 297 nblocks = (dirblocks * 3 + 1) / 2; 298 memreqd = sizeof(*dh) + narrays * sizeof(*dh->dh_hash) + 299 narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) + 300 nblocks * sizeof(*dh->dh_blkfree); 301 DIRHASHLIST_LOCK(); 302 if (memreqd + ufs_dirhashmem > ufs_dirhashmaxmem) { 303 DIRHASHLIST_UNLOCK(); 304 if (memreqd > ufs_dirhashmaxmem / 2) 305 goto fail; 306 /* Try to free some space. */ 307 if (ufsdirhash_recycle(memreqd) != 0) 308 goto fail; 309 /* Enough was freed, and list has been locked. */ 310 } 311 ufs_dirhashmem += memreqd; 312 DIRHASHLIST_UNLOCK(); 313 314 /* Initialise the hash table and block statistics. */ 315 dh->dh_memreq = memreqd; 316 dh->dh_narrays = narrays; 317 dh->dh_hlen = nslots; 318 dh->dh_nblk = nblocks; 319 dh->dh_dirblks = dirblocks; 320 for (i = 0; i < DH_NFSTATS; i++) 321 dh->dh_firstfree[i] = -1; 322 dh->dh_firstfree[DH_NFSTATS] = 0; 323 dh->dh_hused = 0; 324 dh->dh_seqopt = 0; 325 dh->dh_seqoff = 0; 326 dh->dh_score = DH_SCOREINIT; 327 328 /* 329 * Use non-blocking mallocs so that we will revert to a linear 330 * lookup on failure rather than potentially blocking forever. 331 */ 332 MALLOC(dh->dh_hash, doff_t **, narrays * sizeof(dh->dh_hash[0]), 333 M_DIRHASH, M_NOWAIT | M_ZERO); 334 if (dh->dh_hash == NULL) 335 goto fail; 336 MALLOC(dh->dh_blkfree, u_int8_t *, nblocks * sizeof(dh->dh_blkfree[0]), 337 M_DIRHASH, M_NOWAIT); 338 if (dh->dh_blkfree == NULL) 339 goto fail; 340 for (i = 0; i < narrays; i++) { 341 if ((dh->dh_hash[i] = DIRHASH_BLKALLOC_WAITOK()) == NULL) 342 goto fail; 343 for (j = 0; j < DH_NBLKOFF; j++) 344 dh->dh_hash[i][j] = DIRHASH_EMPTY; 345 } 346 for (i = 0; i < dirblocks; i++) 347 dh->dh_blkfree[i] = DIRBLKSIZ / DIRALIGN; 348 bmask = VFSTOUFS(vp->v_mount)->um_mountp->mnt_stat.f_iosize - 1; 349 pos = 0; 350 while (pos < ip->i_size) { 351 /* If necessary, get the next directory block. */ 352 if ((pos & bmask) == 0) { 353 if (bp != NULL) 354 brelse(bp); 355 if (UFS_BLKATOFF(vp, (off_t)pos, NULL, &bp) != 0) 356 goto fail; 357 } 358 359 /* Add this entry to the hash. */ 360 ep = (struct direct *)((char *)bp->b_data + (pos & bmask)); 361 if (ep->d_reclen == 0 || ep->d_reclen > 362 DIRBLKSIZ - (pos & (DIRBLKSIZ - 1))) { 363 /* Corrupted directory. */ 364 brelse(bp); 365 goto fail; 366 } 367 if (ep->d_ino != 0) { 368 /* Add the entry (simplified ufsdirhash_add). */ 369 slot = ufsdirhash_hash(dh, ep->d_name, ep->d_namlen); 370 while (DH_ENTRY(dh, slot) != DIRHASH_EMPTY) 371 slot = WRAPINCR(slot, dh->dh_hlen); 372 dh->dh_hused++; 373 DH_ENTRY(dh, slot) = pos; 374 ufsdirhash_adjfree(dh, pos, -DIRSIZ(0, ep)); 375 } 376 pos += ep->d_reclen; 377 } 378 379 if (bp != NULL) 380 brelse(bp); 381 DIRHASHLIST_LOCK(); 382 TAILQ_INSERT_TAIL(&ufsdirhash_list, dh, dh_list); 383 dh->dh_onlist = 1; 384 DIRHASHLIST_UNLOCK(); 385 lockmgr(&dh->dh_lock, LK_DOWNGRADE, 0); 386 return (0); 387 388fail: 389 ufsdirhash_free_locked(ip); 390 return (-1); 391} 392 393/* 394 * Free any hash table associated with inode 'ip'. 395 */ 396static void 397ufsdirhash_free_locked(struct inode *ip) 398{ 399 struct dirhash *dh; 400 struct vnode *vp; 401 int i; 402 403 DIRHASH_ASSERT_LOCKED(ip->i_dirhash); 404 /* 405 * Clear the pointer in the inode to prevent new threads from 406 * finding the dead structure. 407 */ 408 vp = ip->i_vnode; 409 VI_LOCK(vp); 410 dh = ip->i_dirhash; 411 ip->i_dirhash = NULL; 412 VI_UNLOCK(vp); 413 /* 414 * Drain waiters. They will abort when they see that ip->i_dirhash 415 * is NULL after locking. 416 */ 417 lockmgr(&dh->dh_lock, LK_RELEASE, 0); 418 lockmgr(&dh->dh_lock, LK_DRAIN, 0); 419 /* 420 * Handle partially recycled as well as fully constructed hashes. 421 */ 422 if (dh->dh_hash != NULL) { 423 for (i = 0; i < dh->dh_narrays; i++) 424 if (dh->dh_hash[i] != NULL) 425 DIRHASH_BLKFREE(dh->dh_hash[i]); 426 FREE(dh->dh_hash, M_DIRHASH); 427 if (dh->dh_blkfree != NULL) 428 FREE(dh->dh_blkfree, M_DIRHASH); 429 } 430 DIRHASHLIST_LOCK(); 431 if (dh->dh_onlist) 432 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 433 ufs_dirhashmem -= dh->dh_memreq; 434 DIRHASHLIST_UNLOCK(); 435 /* 436 * Release the lock and reclaim datastructure memory. 437 */ 438 lockmgr(&dh->dh_lock, LK_RELEASE, 0); 439 lockdestroy(&dh->dh_lock); 440 FREE(dh, M_DIRHASH); 441 442 return; 443} 444 445/* 446 * Find the offset of the specified name within the given inode. 447 * Returns 0 on success, ENOENT if the entry does not exist, or 448 * EJUSTRETURN if the caller should revert to a linear search. 449 * 450 * If successful, the directory offset is stored in *offp, and a 451 * pointer to a struct buf containing the entry is stored in *bpp. If 452 * prevoffp is non-NULL, the offset of the previous entry within 453 * the DIRBLKSIZ-sized block is stored in *prevoffp (if the entry 454 * is the first in a block, the start of the block is used). 455 * 456 * Must be called with the hash locked. Returns with the hash unlocked. 457 */ 458int 459ufsdirhash_lookup(struct inode *ip, char *name, int namelen, doff_t *offp, 460 struct buf **bpp, doff_t *prevoffp) 461{ 462 struct dirhash *dh, *dh_next; 463 struct direct *dp; 464 struct vnode *vp; 465 struct buf *bp; 466 doff_t blkoff, bmask, offset, prevoff; 467 int i, slot; 468 int error; 469 470 dh = ip->i_dirhash; 471 KASSERT(dh != NULL && dh->dh_hash != NULL, 472 ("ufsdirhash_lookup: Invalid dirhash %p\n", dh)); 473 DIRHASH_ASSERT_LOCKED(dh); 474 /* 475 * Move this dirhash towards the end of the list if it has a 476 * score higher than the next entry, and acquire the dh_lock. 477 */ 478 DIRHASHLIST_LOCK(); 479 if (TAILQ_NEXT(dh, dh_list) != NULL) { 480 /* 481 * If the new score will be greater than that of the next 482 * entry, then move this entry past it. With both mutexes 483 * held, dh_next won't go away, but its dh_score could 484 * change; that's not important since it is just a hint. 485 */ 486 if ((dh_next = TAILQ_NEXT(dh, dh_list)) != NULL && 487 dh->dh_score >= dh_next->dh_score) { 488 KASSERT(dh->dh_onlist, ("dirhash: not on list")); 489 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 490 TAILQ_INSERT_AFTER(&ufsdirhash_list, dh_next, dh, 491 dh_list); 492 } 493 } 494 /* Update the score. */ 495 if (dh->dh_score < DH_SCOREMAX) 496 dh->dh_score++; 497 DIRHASHLIST_UNLOCK(); 498 499 vp = ip->i_vnode; 500 bmask = VFSTOUFS(vp->v_mount)->um_mountp->mnt_stat.f_iosize - 1; 501 blkoff = -1; 502 bp = NULL; 503restart: 504 slot = ufsdirhash_hash(dh, name, namelen); 505 506 if (dh->dh_seqopt) { 507 /* 508 * Sequential access optimisation. dh_seqoff contains the 509 * offset of the directory entry immediately following 510 * the last entry that was looked up. Check if this offset 511 * appears in the hash chain for the name we are looking for. 512 */ 513 for (i = slot; (offset = DH_ENTRY(dh, i)) != DIRHASH_EMPTY; 514 i = WRAPINCR(i, dh->dh_hlen)) 515 if (offset == dh->dh_seqoff) 516 break; 517 if (offset == dh->dh_seqoff) { 518 /* 519 * We found an entry with the expected offset. This 520 * is probably the entry we want, but if not, the 521 * code below will turn off seqopt and retry. 522 */ 523 slot = i; 524 } else 525 dh->dh_seqopt = 0; 526 } 527 528 for (; (offset = DH_ENTRY(dh, slot)) != DIRHASH_EMPTY; 529 slot = WRAPINCR(slot, dh->dh_hlen)) { 530 if (offset == DIRHASH_DEL) 531 continue; 532 if (offset < 0 || offset >= ip->i_size) 533 panic("ufsdirhash_lookup: bad offset in hash array"); 534 if ((offset & ~bmask) != blkoff) { 535 if (bp != NULL) 536 brelse(bp); 537 blkoff = offset & ~bmask; 538 if (UFS_BLKATOFF(vp, (off_t)blkoff, NULL, &bp) != 0) { 539 error = EJUSTRETURN; 540 goto fail; 541 } 542 } 543 dp = (struct direct *)(bp->b_data + (offset & bmask)); 544 if (dp->d_reclen == 0 || dp->d_reclen > 545 DIRBLKSIZ - (offset & (DIRBLKSIZ - 1))) { 546 /* Corrupted directory. */ 547 error = EJUSTRETURN; 548 goto fail; 549 } 550 if (dp->d_namlen == namelen && 551 bcmp(dp->d_name, name, namelen) == 0) { 552 /* Found. Get the prev offset if needed. */ 553 if (prevoffp != NULL) { 554 if (offset & (DIRBLKSIZ - 1)) { 555 prevoff = ufsdirhash_getprev(dp, 556 offset); 557 if (prevoff == -1) { 558 error = EJUSTRETURN; 559 goto fail; 560 } 561 } else 562 prevoff = offset; 563 *prevoffp = prevoff; 564 } 565 566 /* Check for sequential access, and update offset. */ 567 if (dh->dh_seqopt == 0 && dh->dh_seqoff == offset) 568 dh->dh_seqopt = 1; 569 dh->dh_seqoff = offset + DIRSIZ(0, dp); 570 *bpp = bp; 571 *offp = offset; 572 ufsdirhash_release(dh); 573 return (0); 574 } 575 576 /* 577 * When the name doesn't match in the seqopt case, go back 578 * and search normally. 579 */ 580 if (dh->dh_seqopt) { 581 dh->dh_seqopt = 0; 582 goto restart; 583 } 584 } 585 error = ENOENT; 586fail: 587 ufsdirhash_release(dh); 588 if (bp != NULL) 589 brelse(bp); 590 return (error); 591} 592 593/* 594 * Find a directory block with room for 'slotneeded' bytes. Returns 595 * the offset of the directory entry that begins the free space. 596 * This will either be the offset of an existing entry that has free 597 * space at the end, or the offset of an entry with d_ino == 0 at 598 * the start of a DIRBLKSIZ block. 599 * 600 * To use the space, the caller may need to compact existing entries in 601 * the directory. The total number of bytes in all of the entries involved 602 * in the compaction is stored in *slotsize. In other words, all of 603 * the entries that must be compacted are exactly contained in the 604 * region beginning at the returned offset and spanning *slotsize bytes. 605 * 606 * Returns -1 if no space was found, indicating that the directory 607 * must be extended. 608 */ 609doff_t 610ufsdirhash_findfree(struct inode *ip, int slotneeded, int *slotsize) 611{ 612 struct direct *dp; 613 struct dirhash *dh; 614 struct buf *bp; 615 doff_t pos, slotstart; 616 int dirblock, error, freebytes, i; 617 618 dh = ip->i_dirhash; 619 KASSERT(dh != NULL && dh->dh_hash != NULL, 620 ("ufsdirhash_findfree: Invalid dirhash %p\n", dh)); 621 DIRHASH_ASSERT_LOCKED(dh); 622 623 /* Find a directory block with the desired free space. */ 624 dirblock = -1; 625 for (i = howmany(slotneeded, DIRALIGN); i <= DH_NFSTATS; i++) 626 if ((dirblock = dh->dh_firstfree[i]) != -1) 627 break; 628 if (dirblock == -1) 629 return (-1); 630 631 KASSERT(dirblock < dh->dh_nblk && 632 dh->dh_blkfree[dirblock] >= howmany(slotneeded, DIRALIGN), 633 ("ufsdirhash_findfree: bad stats")); 634 pos = dirblock * DIRBLKSIZ; 635 error = UFS_BLKATOFF(ip->i_vnode, (off_t)pos, (char **)&dp, &bp); 636 if (error) 637 return (-1); 638 639 /* Find the first entry with free space. */ 640 for (i = 0; i < DIRBLKSIZ; ) { 641 if (dp->d_reclen == 0) { 642 brelse(bp); 643 return (-1); 644 } 645 if (dp->d_ino == 0 || dp->d_reclen > DIRSIZ(0, dp)) 646 break; 647 i += dp->d_reclen; 648 dp = (struct direct *)((char *)dp + dp->d_reclen); 649 } 650 if (i > DIRBLKSIZ) { 651 brelse(bp); 652 return (-1); 653 } 654 slotstart = pos + i; 655 656 /* Find the range of entries needed to get enough space */ 657 freebytes = 0; 658 while (i < DIRBLKSIZ && freebytes < slotneeded) { 659 freebytes += dp->d_reclen; 660 if (dp->d_ino != 0) 661 freebytes -= DIRSIZ(0, dp); 662 if (dp->d_reclen == 0) { 663 brelse(bp); 664 return (-1); 665 } 666 i += dp->d_reclen; 667 dp = (struct direct *)((char *)dp + dp->d_reclen); 668 } 669 if (i > DIRBLKSIZ) { 670 brelse(bp); 671 return (-1); 672 } 673 if (freebytes < slotneeded) 674 panic("ufsdirhash_findfree: free mismatch"); 675 brelse(bp); 676 *slotsize = pos + i - slotstart; 677 return (slotstart); 678} 679 680/* 681 * Return the start of the unused space at the end of a directory, or 682 * -1 if there are no trailing unused blocks. 683 */ 684doff_t 685ufsdirhash_enduseful(struct inode *ip) 686{ 687 688 struct dirhash *dh; 689 int i; 690 691 dh = ip->i_dirhash; 692 DIRHASH_ASSERT_LOCKED(dh); 693 KASSERT(dh != NULL && dh->dh_hash != NULL, 694 ("ufsdirhash_enduseful: Invalid dirhash %p\n", dh)); 695 696 if (dh->dh_blkfree[dh->dh_dirblks - 1] != DIRBLKSIZ / DIRALIGN) 697 return (-1); 698 699 for (i = dh->dh_dirblks - 1; i >= 0; i--) 700 if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN) 701 break; 702 703 return ((doff_t)(i + 1) * DIRBLKSIZ); 704} 705 706/* 707 * Insert information into the hash about a new directory entry. dirp 708 * points to a struct direct containing the entry, and offset specifies 709 * the offset of this entry. 710 */ 711void 712ufsdirhash_add(struct inode *ip, struct direct *dirp, doff_t offset) 713{ 714 struct dirhash *dh; 715 int slot; 716 717 if ((dh = ufsdirhash_acquire(ip)) == NULL) 718 return; 719 720 KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ, 721 ("ufsdirhash_add: bad offset")); 722 /* 723 * Normal hash usage is < 66%. If the usage gets too high then 724 * remove the hash entirely and let it be rebuilt later. 725 */ 726 if (dh->dh_hused >= (dh->dh_hlen * 3) / 4) { 727 ufsdirhash_free_locked(ip); 728 return; 729 } 730 731 /* Find a free hash slot (empty or deleted), and add the entry. */ 732 slot = ufsdirhash_hash(dh, dirp->d_name, dirp->d_namlen); 733 while (DH_ENTRY(dh, slot) >= 0) 734 slot = WRAPINCR(slot, dh->dh_hlen); 735 if (DH_ENTRY(dh, slot) == DIRHASH_EMPTY) 736 dh->dh_hused++; 737 DH_ENTRY(dh, slot) = offset; 738 739 /* Update the per-block summary info. */ 740 ufsdirhash_adjfree(dh, offset, -DIRSIZ(0, dirp)); 741 ufsdirhash_release(dh); 742} 743 744/* 745 * Remove the specified directory entry from the hash. The entry to remove 746 * is defined by the name in `dirp', which must exist at the specified 747 * `offset' within the directory. 748 */ 749void 750ufsdirhash_remove(struct inode *ip, struct direct *dirp, doff_t offset) 751{ 752 struct dirhash *dh; 753 int slot; 754 755 if ((dh = ufsdirhash_acquire(ip)) == NULL) 756 return; 757 758 KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ, 759 ("ufsdirhash_remove: bad offset")); 760 /* Find the entry */ 761 slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, offset); 762 763 /* Remove the hash entry. */ 764 ufsdirhash_delslot(dh, slot); 765 766 /* Update the per-block summary info. */ 767 ufsdirhash_adjfree(dh, offset, DIRSIZ(0, dirp)); 768 ufsdirhash_release(dh); 769} 770 771/* 772 * Change the offset associated with a directory entry in the hash. Used 773 * when compacting directory blocks. 774 */ 775void 776ufsdirhash_move(struct inode *ip, struct direct *dirp, doff_t oldoff, 777 doff_t newoff) 778{ 779 struct dirhash *dh; 780 int slot; 781 782 if ((dh = ufsdirhash_acquire(ip)) == NULL) 783 return; 784 785 KASSERT(oldoff < dh->dh_dirblks * DIRBLKSIZ && 786 newoff < dh->dh_dirblks * DIRBLKSIZ, 787 ("ufsdirhash_move: bad offset")); 788 /* Find the entry, and update the offset. */ 789 slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, oldoff); 790 DH_ENTRY(dh, slot) = newoff; 791 ufsdirhash_release(dh); 792} 793 794/* 795 * Inform dirhash that the directory has grown by one block that 796 * begins at offset (i.e. the new length is offset + DIRBLKSIZ). 797 */ 798void 799ufsdirhash_newblk(struct inode *ip, doff_t offset) 800{ 801 struct dirhash *dh; 802 int block; 803 804 if ((dh = ufsdirhash_acquire(ip)) == NULL) 805 return; 806 807 KASSERT(offset == dh->dh_dirblks * DIRBLKSIZ, 808 ("ufsdirhash_newblk: bad offset")); 809 block = offset / DIRBLKSIZ; 810 if (block >= dh->dh_nblk) { 811 /* Out of space; must rebuild. */ 812 ufsdirhash_free_locked(ip); 813 return; 814 } 815 dh->dh_dirblks = block + 1; 816 817 /* Account for the new free block. */ 818 dh->dh_blkfree[block] = DIRBLKSIZ / DIRALIGN; 819 if (dh->dh_firstfree[DH_NFSTATS] == -1) 820 dh->dh_firstfree[DH_NFSTATS] = block; 821 ufsdirhash_release(dh); 822} 823 824/* 825 * Inform dirhash that the directory is being truncated. 826 */ 827void 828ufsdirhash_dirtrunc(struct inode *ip, doff_t offset) 829{ 830 struct dirhash *dh; 831 int block, i; 832 833 if ((dh = ufsdirhash_acquire(ip)) == NULL) 834 return; 835 836 KASSERT(offset <= dh->dh_dirblks * DIRBLKSIZ, 837 ("ufsdirhash_dirtrunc: bad offset")); 838 block = howmany(offset, DIRBLKSIZ); 839 /* 840 * If the directory shrinks to less than 1/8 of dh_nblk blocks 841 * (about 20% of its original size due to the 50% extra added in 842 * ufsdirhash_build) then free it, and let the caller rebuild 843 * if necessary. 844 */ 845 if (block < dh->dh_nblk / 8 && dh->dh_narrays > 1) { 846 ufsdirhash_free_locked(ip); 847 return; 848 } 849 850 /* 851 * Remove any `first free' information pertaining to the 852 * truncated blocks. All blocks we're removing should be 853 * completely unused. 854 */ 855 if (dh->dh_firstfree[DH_NFSTATS] >= block) 856 dh->dh_firstfree[DH_NFSTATS] = -1; 857 for (i = block; i < dh->dh_dirblks; i++) 858 if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN) 859 panic("ufsdirhash_dirtrunc: blocks in use"); 860 for (i = 0; i < DH_NFSTATS; i++) 861 if (dh->dh_firstfree[i] >= block) 862 panic("ufsdirhash_dirtrunc: first free corrupt"); 863 dh->dh_dirblks = block; 864 ufsdirhash_release(dh); 865} 866 867/* 868 * Debugging function to check that the dirhash information about 869 * a directory block matches its actual contents. Panics if a mismatch 870 * is detected. 871 * 872 * On entry, `buf' should point to the start of an in-core 873 * DIRBLKSIZ-sized directory block, and `offset' should contain the 874 * offset from the start of the directory of that block. 875 */ 876void 877ufsdirhash_checkblock(struct inode *ip, char *buf, doff_t offset) 878{ 879 struct dirhash *dh; 880 struct direct *dp; 881 int block, ffslot, i, nfree; 882 883 if (!ufs_dirhashcheck) 884 return; 885 if ((dh = ufsdirhash_acquire(ip)) == NULL) 886 return; 887 888 block = offset / DIRBLKSIZ; 889 if ((offset & (DIRBLKSIZ - 1)) != 0 || block >= dh->dh_dirblks) 890 panic("ufsdirhash_checkblock: bad offset"); 891 892 nfree = 0; 893 for (i = 0; i < DIRBLKSIZ; i += dp->d_reclen) { 894 dp = (struct direct *)(buf + i); 895 if (dp->d_reclen == 0 || i + dp->d_reclen > DIRBLKSIZ) 896 panic("ufsdirhash_checkblock: bad dir"); 897 898 if (dp->d_ino == 0) { 899#if 0 900 /* 901 * XXX entries with d_ino == 0 should only occur 902 * at the start of a DIRBLKSIZ block. However the 903 * ufs code is tolerant of such entries at other 904 * offsets, and fsck does not fix them. 905 */ 906 if (i != 0) 907 panic("ufsdirhash_checkblock: bad dir inode"); 908#endif 909 nfree += dp->d_reclen; 910 continue; 911 } 912 913 /* Check that the entry exists (will panic if it doesn't). */ 914 ufsdirhash_findslot(dh, dp->d_name, dp->d_namlen, offset + i); 915 916 nfree += dp->d_reclen - DIRSIZ(0, dp); 917 } 918 if (i != DIRBLKSIZ) 919 panic("ufsdirhash_checkblock: bad dir end"); 920 921 if (dh->dh_blkfree[block] * DIRALIGN != nfree) 922 panic("ufsdirhash_checkblock: bad free count"); 923 924 ffslot = BLKFREE2IDX(nfree / DIRALIGN); 925 for (i = 0; i <= DH_NFSTATS; i++) 926 if (dh->dh_firstfree[i] == block && i != ffslot) 927 panic("ufsdirhash_checkblock: bad first-free"); 928 if (dh->dh_firstfree[ffslot] == -1) 929 panic("ufsdirhash_checkblock: missing first-free entry"); 930 ufsdirhash_release(dh); 931} 932 933/* 934 * Hash the specified filename into a dirhash slot. 935 */ 936static int 937ufsdirhash_hash(struct dirhash *dh, char *name, int namelen) 938{ 939 u_int32_t hash; 940 941 /* 942 * We hash the name and then some other bit of data that is 943 * invariant over the dirhash's lifetime. Otherwise names 944 * differing only in the last byte are placed close to one 945 * another in the table, which is bad for linear probing. 946 */ 947 hash = fnv_32_buf(name, namelen, FNV1_32_INIT); 948 hash = fnv_32_buf(&dh, sizeof(dh), hash); 949 return (hash % dh->dh_hlen); 950} 951 952/* 953 * Adjust the number of free bytes in the block containing `offset' 954 * by the value specified by `diff'. 955 * 956 * The caller must ensure we have exclusive access to `dh'; normally 957 * that means that dh_lock should be held, but this is also called 958 * from ufsdirhash_build() where exclusive access can be assumed. 959 */ 960static void 961ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff) 962{ 963 int block, i, nfidx, ofidx; 964 965 /* Update the per-block summary info. */ 966 block = offset / DIRBLKSIZ; 967 KASSERT(block < dh->dh_nblk && block < dh->dh_dirblks, 968 ("dirhash bad offset")); 969 ofidx = BLKFREE2IDX(dh->dh_blkfree[block]); 970 dh->dh_blkfree[block] = (int)dh->dh_blkfree[block] + (diff / DIRALIGN); 971 nfidx = BLKFREE2IDX(dh->dh_blkfree[block]); 972 973 /* Update the `first free' list if necessary. */ 974 if (ofidx != nfidx) { 975 /* If removing, scan forward for the next block. */ 976 if (dh->dh_firstfree[ofidx] == block) { 977 for (i = block + 1; i < dh->dh_dirblks; i++) 978 if (BLKFREE2IDX(dh->dh_blkfree[i]) == ofidx) 979 break; 980 dh->dh_firstfree[ofidx] = (i < dh->dh_dirblks) ? i : -1; 981 } 982 983 /* Make this the new `first free' if necessary */ 984 if (dh->dh_firstfree[nfidx] > block || 985 dh->dh_firstfree[nfidx] == -1) 986 dh->dh_firstfree[nfidx] = block; 987 } 988} 989 990/* 991 * Find the specified name which should have the specified offset. 992 * Returns a slot number, and panics on failure. 993 * 994 * `dh' must be locked on entry and remains so on return. 995 */ 996static int 997ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, doff_t offset) 998{ 999 int slot; 1000 1001 DIRHASH_ASSERT_LOCKED(dh); 1002 1003 /* Find the entry. */ 1004 KASSERT(dh->dh_hused < dh->dh_hlen, ("dirhash find full")); 1005 slot = ufsdirhash_hash(dh, name, namelen); 1006 while (DH_ENTRY(dh, slot) != offset && 1007 DH_ENTRY(dh, slot) != DIRHASH_EMPTY) 1008 slot = WRAPINCR(slot, dh->dh_hlen); 1009 if (DH_ENTRY(dh, slot) != offset) 1010 panic("ufsdirhash_findslot: '%.*s' not found", namelen, name); 1011 1012 return (slot); 1013} 1014 1015/* 1016 * Remove the entry corresponding to the specified slot from the hash array. 1017 * 1018 * `dh' must be locked on entry and remains so on return. 1019 */ 1020static void 1021ufsdirhash_delslot(struct dirhash *dh, int slot) 1022{ 1023 int i; 1024 1025 DIRHASH_ASSERT_LOCKED(dh); 1026 1027 /* Mark the entry as deleted. */ 1028 DH_ENTRY(dh, slot) = DIRHASH_DEL; 1029 1030 /* If this is the end of a chain of DIRHASH_DEL slots, remove them. */ 1031 for (i = slot; DH_ENTRY(dh, i) == DIRHASH_DEL; ) 1032 i = WRAPINCR(i, dh->dh_hlen); 1033 if (DH_ENTRY(dh, i) == DIRHASH_EMPTY) { 1034 i = WRAPDECR(i, dh->dh_hlen); 1035 while (DH_ENTRY(dh, i) == DIRHASH_DEL) { 1036 DH_ENTRY(dh, i) = DIRHASH_EMPTY; 1037 dh->dh_hused--; 1038 i = WRAPDECR(i, dh->dh_hlen); 1039 } 1040 KASSERT(dh->dh_hused >= 0, ("ufsdirhash_delslot neg hlen")); 1041 } 1042} 1043 1044/* 1045 * Given a directory entry and its offset, find the offset of the 1046 * previous entry in the same DIRBLKSIZ-sized block. Returns an 1047 * offset, or -1 if there is no previous entry in the block or some 1048 * other problem occurred. 1049 */ 1050static doff_t 1051ufsdirhash_getprev(struct direct *dirp, doff_t offset) 1052{ 1053 struct direct *dp; 1054 char *blkbuf; 1055 doff_t blkoff, prevoff; 1056 int entrypos, i; 1057 1058 blkoff = offset & ~(DIRBLKSIZ - 1); /* offset of start of block */ 1059 entrypos = offset & (DIRBLKSIZ - 1); /* entry relative to block */ 1060 blkbuf = (char *)dirp - entrypos; 1061 prevoff = blkoff; 1062 1063 /* If `offset' is the start of a block, there is no previous entry. */ 1064 if (entrypos == 0) 1065 return (-1); 1066 1067 /* Scan from the start of the block until we get to the entry. */ 1068 for (i = 0; i < entrypos; i += dp->d_reclen) { 1069 dp = (struct direct *)(blkbuf + i); 1070 if (dp->d_reclen == 0 || i + dp->d_reclen > entrypos) 1071 return (-1); /* Corrupted directory. */ 1072 prevoff = blkoff + i; 1073 } 1074 return (prevoff); 1075} 1076 1077/* 1078 * Try to free up `wanted' bytes by stealing memory from existing 1079 * dirhashes. Returns zero with list locked if successful. 1080 */ 1081static int 1082ufsdirhash_recycle(int wanted) 1083{ 1084 struct dirhash *dh; 1085 doff_t **hash; 1086 u_int8_t *blkfree; 1087 int i, mem, narrays; 1088 1089 DIRHASHLIST_LOCK(); 1090 dh = TAILQ_FIRST(&ufsdirhash_list); 1091 while (wanted + ufs_dirhashmem > ufs_dirhashmaxmem) { 1092 /* Decrement the score; only recycle if it becomes zero. */ 1093 if (dh == NULL || --dh->dh_score > 0) { 1094 DIRHASHLIST_UNLOCK(); 1095 return (-1); 1096 } 1097 /* 1098 * If we can't lock it it's in use and we don't want to 1099 * recycle it anyway. 1100 */ 1101 if (lockmgr(&dh->dh_lock, LK_EXCLUSIVE | LK_NOWAIT, NULL)) { 1102 dh = TAILQ_NEXT(dh, dh_list); 1103 continue; 1104 } 1105 KASSERT(dh->dh_hash != NULL, ("dirhash: NULL hash on list")); 1106 1107 /* Remove it from the list and detach its memory. */ 1108 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 1109 dh->dh_onlist = 0; 1110 hash = dh->dh_hash; 1111 dh->dh_hash = NULL; 1112 blkfree = dh->dh_blkfree; 1113 dh->dh_blkfree = NULL; 1114 narrays = dh->dh_narrays; 1115 mem = dh->dh_memreq; 1116 dh->dh_memreq = 0; 1117 1118 /* Unlock everything, free the detached memory. */ 1119 ufsdirhash_release(dh); 1120 DIRHASHLIST_UNLOCK(); 1121 for (i = 0; i < narrays; i++) 1122 DIRHASH_BLKFREE(hash[i]); 1123 FREE(hash, M_DIRHASH); 1124 FREE(blkfree, M_DIRHASH); 1125 1126 /* Account for the returned memory, and repeat if necessary. */ 1127 DIRHASHLIST_LOCK(); 1128 ufs_dirhashmem -= mem; 1129 dh = TAILQ_FIRST(&ufsdirhash_list); 1130 } 1131 /* Success; return with list locked. */ 1132 return (0); 1133} 1134 1135 1136void 1137ufsdirhash_init() 1138{ 1139 ufsdirhash_zone = uma_zcreate("DIRHASH", DH_NBLKOFF * sizeof(doff_t), 1140 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 1141 mtx_init(&ufsdirhash_mtx, "dirhash list", NULL, MTX_DEF); 1142 TAILQ_INIT(&ufsdirhash_list); 1143} 1144 1145void 1146ufsdirhash_uninit() 1147{ 1148 KASSERT(TAILQ_EMPTY(&ufsdirhash_list), ("ufsdirhash_uninit")); 1149 uma_zdestroy(ufsdirhash_zone); 1150 mtx_destroy(&ufsdirhash_mtx); 1151} 1152 1153#endif /* UFS_DIRHASH */ 1154