ufs_dirhash.c revision 274835
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 274835 2014-11-22 00:42:30Z davide $"); 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_dirhashreclaimpercent = 10; 89static int ufsdirhash_set_reclaimpercent(SYSCTL_HANDLER_ARGS); 90SYSCTL_PROC(_vfs_ufs, OID_AUTO, dirhash_reclaimpercent, 91 CTLTYPE_INT | CTLFLAG_RW, 0, 0, ufsdirhash_set_reclaimpercent, "I", 92 "set percentage of dirhash cache to be removed in low VM events"); 93 94 95static int ufsdirhash_hash(struct dirhash *dh, char *name, int namelen); 96static void ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff); 97static void ufsdirhash_delslot(struct dirhash *dh, int slot); 98static int ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, 99 doff_t offset); 100static doff_t ufsdirhash_getprev(struct direct *dp, doff_t offset); 101static int ufsdirhash_recycle(int wanted); 102static void ufsdirhash_lowmem(void); 103static void ufsdirhash_free_locked(struct inode *ip); 104 105static uma_zone_t ufsdirhash_zone; 106 107#define DIRHASHLIST_LOCK() mtx_lock(&ufsdirhash_mtx) 108#define DIRHASHLIST_UNLOCK() mtx_unlock(&ufsdirhash_mtx) 109#define DIRHASH_BLKALLOC_WAITOK() uma_zalloc(ufsdirhash_zone, M_WAITOK) 110#define DIRHASH_BLKFREE(ptr) uma_zfree(ufsdirhash_zone, (ptr)) 111#define DIRHASH_ASSERT_LOCKED(dh) \ 112 sx_assert(&(dh)->dh_lock, SA_LOCKED) 113 114/* Dirhash list; recently-used entries are near the tail. */ 115static TAILQ_HEAD(, dirhash) ufsdirhash_list; 116 117/* Protects: ufsdirhash_list, `dh_list' field, ufs_dirhashmem. */ 118static struct mtx ufsdirhash_mtx; 119 120/* 121 * Locking: 122 * 123 * The relationship between inode and dirhash is protected either by an 124 * exclusive vnode lock or the vnode interlock where a shared vnode lock 125 * may be used. The dirhash_mtx is acquired after the dirhash lock. To 126 * handle teardown races, code wishing to lock the dirhash for an inode 127 * when using a shared vnode lock must obtain a private reference on the 128 * dirhash while holding the vnode interlock. They can drop it once they 129 * have obtained the dirhash lock and verified that the dirhash wasn't 130 * recycled while they waited for the dirhash lock. 131 * 132 * ufsdirhash_build() acquires a shared lock on the dirhash when it is 133 * successful. This lock is released after a call to ufsdirhash_lookup(). 134 * 135 * Functions requiring exclusive access use ufsdirhash_acquire() which may 136 * free a dirhash structure that was recycled by ufsdirhash_recycle(). 137 * 138 * The dirhash lock may be held across io operations. 139 * 140 * WITNESS reports a lock order reversal between the "bufwait" lock 141 * and the "dirhash" lock. However, this specific reversal will not 142 * cause a deadlock. To get a deadlock, one would have to lock a 143 * buffer followed by the dirhash while a second thread locked a 144 * buffer while holding the dirhash lock. The second order can happen 145 * under a shared or exclusive vnode lock for the associated directory 146 * in lookup(). The first order, however, can only happen under an 147 * exclusive vnode lock (e.g. unlink(), rename(), etc.). Thus, for 148 * a thread to be doing a "bufwait" -> "dirhash" order, it has to hold 149 * an exclusive vnode lock. That exclusive vnode lock will prevent 150 * any other threads from doing a "dirhash" -> "bufwait" order. 151 */ 152 153static void 154ufsdirhash_hold(struct dirhash *dh) 155{ 156 157 refcount_acquire(&dh->dh_refcount); 158} 159 160static void 161ufsdirhash_drop(struct dirhash *dh) 162{ 163 164 if (refcount_release(&dh->dh_refcount)) { 165 sx_destroy(&dh->dh_lock); 166 free(dh, M_DIRHASH); 167 } 168} 169 170/* 171 * Release the lock on a dirhash. 172 */ 173static void 174ufsdirhash_release(struct dirhash *dh) 175{ 176 177 sx_unlock(&dh->dh_lock); 178} 179 180/* 181 * Either acquire an existing hash locked shared or create a new hash and 182 * return it exclusively locked. May return NULL if the allocation fails. 183 * 184 * The vnode interlock is used to protect the i_dirhash pointer from 185 * simultaneous access while only a shared vnode lock is held. 186 */ 187static struct dirhash * 188ufsdirhash_create(struct inode *ip) 189{ 190 struct dirhash *ndh; 191 struct dirhash *dh; 192 struct vnode *vp; 193 int error; 194 195 error = 0; 196 ndh = dh = NULL; 197 vp = ip->i_vnode; 198 for (;;) { 199 /* Racy check for i_dirhash to prefetch a dirhash structure. */ 200 if (ip->i_dirhash == NULL && ndh == NULL) { 201 ndh = malloc(sizeof *dh, M_DIRHASH, 202 M_NOWAIT | M_ZERO); 203 if (ndh == NULL) 204 return (NULL); 205 refcount_init(&ndh->dh_refcount, 1); 206 207 /* 208 * The DUPOK is to prevent warnings from the 209 * sx_slock() a few lines down which is safe 210 * since the duplicate lock in that case is 211 * the one for this dirhash we are creating 212 * now which has no external references until 213 * after this function returns. 214 */ 215 sx_init_flags(&ndh->dh_lock, "dirhash", SX_DUPOK); 216 sx_xlock(&ndh->dh_lock); 217 } 218 /* 219 * Check i_dirhash. If it's NULL just try to use a 220 * preallocated structure. If none exists loop and try again. 221 */ 222 VI_LOCK(vp); 223 dh = ip->i_dirhash; 224 if (dh == NULL) { 225 ip->i_dirhash = ndh; 226 VI_UNLOCK(vp); 227 if (ndh == NULL) 228 continue; 229 return (ndh); 230 } 231 ufsdirhash_hold(dh); 232 VI_UNLOCK(vp); 233 234 /* Acquire a shared lock on existing hashes. */ 235 sx_slock(&dh->dh_lock); 236 237 /* The hash could've been recycled while we were waiting. */ 238 VI_LOCK(vp); 239 if (ip->i_dirhash != dh) { 240 VI_UNLOCK(vp); 241 ufsdirhash_release(dh); 242 ufsdirhash_drop(dh); 243 continue; 244 } 245 VI_UNLOCK(vp); 246 ufsdirhash_drop(dh); 247 248 /* If the hash is still valid we've succeeded. */ 249 if (dh->dh_hash != NULL) 250 break; 251 /* 252 * If the hash is NULL it has been recycled. Try to upgrade 253 * so we can recreate it. If we fail the upgrade, drop our 254 * lock and try again. 255 */ 256 if (sx_try_upgrade(&dh->dh_lock)) 257 break; 258 sx_sunlock(&dh->dh_lock); 259 } 260 /* Free the preallocated structure if it was not necessary. */ 261 if (ndh) { 262 ufsdirhash_release(ndh); 263 ufsdirhash_drop(ndh); 264 } 265 return (dh); 266} 267 268/* 269 * Acquire an exclusive lock on an existing hash. Requires an exclusive 270 * vnode lock to protect the i_dirhash pointer. hashes that have been 271 * recycled are reclaimed here and NULL is returned. 272 */ 273static struct dirhash * 274ufsdirhash_acquire(struct inode *ip) 275{ 276 struct dirhash *dh; 277 struct vnode *vp; 278 279 ASSERT_VOP_ELOCKED(ip->i_vnode, __FUNCTION__); 280 281 vp = ip->i_vnode; 282 dh = ip->i_dirhash; 283 if (dh == NULL) 284 return (NULL); 285 sx_xlock(&dh->dh_lock); 286 if (dh->dh_hash != NULL) 287 return (dh); 288 ufsdirhash_free_locked(ip); 289 return (NULL); 290} 291 292/* 293 * Acquire exclusively and free the hash pointed to by ip. Works with a 294 * shared or exclusive vnode lock. 295 */ 296void 297ufsdirhash_free(struct inode *ip) 298{ 299 struct dirhash *dh; 300 struct vnode *vp; 301 302 vp = ip->i_vnode; 303 for (;;) { 304 /* Grab a reference on this inode's dirhash if it has one. */ 305 VI_LOCK(vp); 306 dh = ip->i_dirhash; 307 if (dh == NULL) { 308 VI_UNLOCK(vp); 309 return; 310 } 311 ufsdirhash_hold(dh); 312 VI_UNLOCK(vp); 313 314 /* Exclusively lock the dirhash. */ 315 sx_xlock(&dh->dh_lock); 316 317 /* If this dirhash still belongs to this inode, then free it. */ 318 VI_LOCK(vp); 319 if (ip->i_dirhash == dh) { 320 VI_UNLOCK(vp); 321 ufsdirhash_drop(dh); 322 break; 323 } 324 VI_UNLOCK(vp); 325 326 /* 327 * This inode's dirhash has changed while we were 328 * waiting for the dirhash lock, so try again. 329 */ 330 ufsdirhash_release(dh); 331 ufsdirhash_drop(dh); 332 } 333 ufsdirhash_free_locked(ip); 334} 335 336/* 337 * Attempt to build up a hash table for the directory contents in 338 * inode 'ip'. Returns 0 on success, or -1 of the operation failed. 339 */ 340int 341ufsdirhash_build(struct inode *ip) 342{ 343 struct dirhash *dh; 344 struct buf *bp = NULL; 345 struct direct *ep; 346 struct vnode *vp; 347 doff_t bmask, pos; 348 int dirblocks, i, j, memreqd, nblocks, narrays, nslots, slot; 349 350 /* Take care of a decreased sysctl value. */ 351 while (ufs_dirhashmem > ufs_dirhashmaxmem) { 352 if (ufsdirhash_recycle(0) != 0) 353 return (-1); 354 /* Recycled enough memory, so unlock the list. */ 355 DIRHASHLIST_UNLOCK(); 356 } 357 358 /* Check if we can/should use dirhash. */ 359 if (ip->i_size < ufs_mindirhashsize || OFSFMT(ip->i_vnode) || 360 ip->i_effnlink == 0) { 361 if (ip->i_dirhash) 362 ufsdirhash_free(ip); 363 return (-1); 364 } 365 dh = ufsdirhash_create(ip); 366 if (dh == NULL) 367 return (-1); 368 if (dh->dh_hash != NULL) 369 return (0); 370 371 vp = ip->i_vnode; 372 /* Allocate 50% more entries than this dir size could ever need. */ 373 KASSERT(ip->i_size >= DIRBLKSIZ, ("ufsdirhash_build size")); 374 nslots = ip->i_size / DIRECTSIZ(1); 375 nslots = (nslots * 3 + 1) / 2; 376 narrays = howmany(nslots, DH_NBLKOFF); 377 nslots = narrays * DH_NBLKOFF; 378 dirblocks = howmany(ip->i_size, DIRBLKSIZ); 379 nblocks = (dirblocks * 3 + 1) / 2; 380 memreqd = sizeof(*dh) + narrays * sizeof(*dh->dh_hash) + 381 narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) + 382 nblocks * sizeof(*dh->dh_blkfree); 383 DIRHASHLIST_LOCK(); 384 if (memreqd + ufs_dirhashmem > ufs_dirhashmaxmem) { 385 DIRHASHLIST_UNLOCK(); 386 if (memreqd > ufs_dirhashmaxmem / 2) 387 goto fail; 388 /* Try to free some space. */ 389 if (ufsdirhash_recycle(memreqd) != 0) 390 goto fail; 391 /* Enough was freed, and list has been locked. */ 392 } 393 ufs_dirhashmem += memreqd; 394 DIRHASHLIST_UNLOCK(); 395 396 /* Initialise the hash table and block statistics. */ 397 dh->dh_memreq = memreqd; 398 dh->dh_narrays = narrays; 399 dh->dh_hlen = nslots; 400 dh->dh_nblk = nblocks; 401 dh->dh_dirblks = dirblocks; 402 for (i = 0; i < DH_NFSTATS; i++) 403 dh->dh_firstfree[i] = -1; 404 dh->dh_firstfree[DH_NFSTATS] = 0; 405 dh->dh_hused = 0; 406 dh->dh_seqoff = -1; 407 dh->dh_score = DH_SCOREINIT; 408 dh->dh_lastused = time_second; 409 410 /* 411 * Use non-blocking mallocs so that we will revert to a linear 412 * lookup on failure rather than potentially blocking forever. 413 */ 414 dh->dh_hash = malloc(narrays * sizeof(dh->dh_hash[0]), 415 M_DIRHASH, M_NOWAIT | M_ZERO); 416 if (dh->dh_hash == NULL) 417 goto fail; 418 dh->dh_blkfree = malloc(nblocks * sizeof(dh->dh_blkfree[0]), 419 M_DIRHASH, M_NOWAIT); 420 if (dh->dh_blkfree == NULL) 421 goto fail; 422 for (i = 0; i < narrays; i++) { 423 if ((dh->dh_hash[i] = DIRHASH_BLKALLOC_WAITOK()) == NULL) 424 goto fail; 425 for (j = 0; j < DH_NBLKOFF; j++) 426 dh->dh_hash[i][j] = DIRHASH_EMPTY; 427 } 428 for (i = 0; i < dirblocks; i++) 429 dh->dh_blkfree[i] = DIRBLKSIZ / DIRALIGN; 430 bmask = vp->v_mount->mnt_stat.f_iosize - 1; 431 pos = 0; 432 while (pos < ip->i_size) { 433 /* If necessary, get the next directory block. */ 434 if ((pos & bmask) == 0) { 435 if (bp != NULL) 436 brelse(bp); 437 if (UFS_BLKATOFF(vp, (off_t)pos, NULL, &bp) != 0) 438 goto fail; 439 } 440 441 /* Add this entry to the hash. */ 442 ep = (struct direct *)((char *)bp->b_data + (pos & bmask)); 443 if (ep->d_reclen == 0 || ep->d_reclen > 444 DIRBLKSIZ - (pos & (DIRBLKSIZ - 1))) { 445 /* Corrupted directory. */ 446 brelse(bp); 447 goto fail; 448 } 449 if (ep->d_ino != 0) { 450 /* Add the entry (simplified ufsdirhash_add). */ 451 slot = ufsdirhash_hash(dh, ep->d_name, ep->d_namlen); 452 while (DH_ENTRY(dh, slot) != DIRHASH_EMPTY) 453 slot = WRAPINCR(slot, dh->dh_hlen); 454 dh->dh_hused++; 455 DH_ENTRY(dh, slot) = pos; 456 ufsdirhash_adjfree(dh, pos, -DIRSIZ(0, ep)); 457 } 458 pos += ep->d_reclen; 459 } 460 461 if (bp != NULL) 462 brelse(bp); 463 DIRHASHLIST_LOCK(); 464 TAILQ_INSERT_TAIL(&ufsdirhash_list, dh, dh_list); 465 dh->dh_onlist = 1; 466 DIRHASHLIST_UNLOCK(); 467 sx_downgrade(&dh->dh_lock); 468 return (0); 469 470fail: 471 ufsdirhash_free_locked(ip); 472 return (-1); 473} 474 475/* 476 * Free any hash table associated with inode 'ip'. 477 */ 478static void 479ufsdirhash_free_locked(struct inode *ip) 480{ 481 struct dirhash *dh; 482 struct vnode *vp; 483 int i; 484 485 DIRHASH_ASSERT_LOCKED(ip->i_dirhash); 486 487 /* 488 * Clear the pointer in the inode to prevent new threads from 489 * finding the dead structure. 490 */ 491 vp = ip->i_vnode; 492 VI_LOCK(vp); 493 dh = ip->i_dirhash; 494 ip->i_dirhash = NULL; 495 VI_UNLOCK(vp); 496 497 /* 498 * Remove the hash from the list since we are going to free its 499 * memory. 500 */ 501 DIRHASHLIST_LOCK(); 502 if (dh->dh_onlist) 503 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 504 ufs_dirhashmem -= dh->dh_memreq; 505 DIRHASHLIST_UNLOCK(); 506 507 /* 508 * At this point, any waiters for the lock should hold their 509 * own reference on the dirhash structure. They will drop 510 * that reference once they grab the vnode interlock and see 511 * that ip->i_dirhash is NULL. 512 */ 513 sx_xunlock(&dh->dh_lock); 514 515 /* 516 * Handle partially recycled as well as fully constructed hashes. 517 */ 518 if (dh->dh_hash != NULL) { 519 for (i = 0; i < dh->dh_narrays; i++) 520 if (dh->dh_hash[i] != NULL) 521 DIRHASH_BLKFREE(dh->dh_hash[i]); 522 free(dh->dh_hash, M_DIRHASH); 523 if (dh->dh_blkfree != NULL) 524 free(dh->dh_blkfree, M_DIRHASH); 525 } 526 527 /* 528 * Drop the inode's reference to the data structure. 529 */ 530 ufsdirhash_drop(dh); 531} 532 533/* 534 * Find the offset of the specified name within the given inode. 535 * Returns 0 on success, ENOENT if the entry does not exist, or 536 * EJUSTRETURN if the caller should revert to a linear search. 537 * 538 * If successful, the directory offset is stored in *offp, and a 539 * pointer to a struct buf containing the entry is stored in *bpp. If 540 * prevoffp is non-NULL, the offset of the previous entry within 541 * the DIRBLKSIZ-sized block is stored in *prevoffp (if the entry 542 * is the first in a block, the start of the block is used). 543 * 544 * Must be called with the hash locked. Returns with the hash unlocked. 545 */ 546int 547ufsdirhash_lookup(struct inode *ip, char *name, int namelen, doff_t *offp, 548 struct buf **bpp, doff_t *prevoffp) 549{ 550 struct dirhash *dh, *dh_next; 551 struct direct *dp; 552 struct vnode *vp; 553 struct buf *bp; 554 doff_t blkoff, bmask, offset, prevoff, seqoff; 555 int i, slot; 556 int error; 557 558 dh = ip->i_dirhash; 559 KASSERT(dh != NULL && dh->dh_hash != NULL, 560 ("ufsdirhash_lookup: Invalid dirhash %p\n", dh)); 561 DIRHASH_ASSERT_LOCKED(dh); 562 /* 563 * Move this dirhash towards the end of the list if it has a 564 * score higher than the next entry, and acquire the dh_lock. 565 */ 566 DIRHASHLIST_LOCK(); 567 if (TAILQ_NEXT(dh, dh_list) != NULL) { 568 /* 569 * If the new score will be greater than that of the next 570 * entry, then move this entry past it. With both mutexes 571 * held, dh_next won't go away, but its dh_score could 572 * change; that's not important since it is just a hint. 573 */ 574 if ((dh_next = TAILQ_NEXT(dh, dh_list)) != NULL && 575 dh->dh_score >= dh_next->dh_score) { 576 KASSERT(dh->dh_onlist, ("dirhash: not on list")); 577 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 578 TAILQ_INSERT_AFTER(&ufsdirhash_list, dh_next, dh, 579 dh_list); 580 } 581 } 582 /* Update the score. */ 583 if (dh->dh_score < DH_SCOREMAX) 584 dh->dh_score++; 585 586 /* Update last used time. */ 587 dh->dh_lastused = time_second; 588 DIRHASHLIST_UNLOCK(); 589 590 vp = ip->i_vnode; 591 bmask = vp->v_mount->mnt_stat.f_iosize - 1; 592 blkoff = -1; 593 bp = NULL; 594 seqoff = dh->dh_seqoff; 595restart: 596 slot = ufsdirhash_hash(dh, name, namelen); 597 598 if (seqoff != -1) { 599 /* 600 * Sequential access optimisation. seqoff contains the 601 * offset of the directory entry immediately following 602 * the last entry that was looked up. Check if this offset 603 * appears in the hash chain for the name we are looking for. 604 */ 605 for (i = slot; (offset = DH_ENTRY(dh, i)) != DIRHASH_EMPTY; 606 i = WRAPINCR(i, dh->dh_hlen)) 607 if (offset == seqoff) 608 break; 609 if (offset == seqoff) { 610 /* 611 * We found an entry with the expected offset. This 612 * is probably the entry we want, but if not, the 613 * code below will retry. 614 */ 615 slot = i; 616 } else 617 seqoff = -1; 618 } 619 620 for (; (offset = DH_ENTRY(dh, slot)) != DIRHASH_EMPTY; 621 slot = WRAPINCR(slot, dh->dh_hlen)) { 622 if (offset == DIRHASH_DEL) 623 continue; 624 if (offset < 0 || offset >= ip->i_size) 625 panic("ufsdirhash_lookup: bad offset in hash array"); 626 if ((offset & ~bmask) != blkoff) { 627 if (bp != NULL) 628 brelse(bp); 629 blkoff = offset & ~bmask; 630 if (UFS_BLKATOFF(vp, (off_t)blkoff, NULL, &bp) != 0) { 631 error = EJUSTRETURN; 632 goto fail; 633 } 634 } 635 KASSERT(bp != NULL, ("no buffer allocated")); 636 dp = (struct direct *)(bp->b_data + (offset & bmask)); 637 if (dp->d_reclen == 0 || dp->d_reclen > 638 DIRBLKSIZ - (offset & (DIRBLKSIZ - 1))) { 639 /* Corrupted directory. */ 640 error = EJUSTRETURN; 641 goto fail; 642 } 643 if (dp->d_namlen == namelen && 644 bcmp(dp->d_name, name, namelen) == 0) { 645 /* Found. Get the prev offset if needed. */ 646 if (prevoffp != NULL) { 647 if (offset & (DIRBLKSIZ - 1)) { 648 prevoff = ufsdirhash_getprev(dp, 649 offset); 650 if (prevoff == -1) { 651 error = EJUSTRETURN; 652 goto fail; 653 } 654 } else 655 prevoff = offset; 656 *prevoffp = prevoff; 657 } 658 659 /* Update offset. */ 660 dh->dh_seqoff = offset + DIRSIZ(0, dp); 661 *bpp = bp; 662 *offp = offset; 663 ufsdirhash_release(dh); 664 return (0); 665 } 666 667 /* 668 * When the name doesn't match in the sequential 669 * optimization case, go back and search normally. 670 */ 671 if (seqoff != -1) { 672 seqoff = -1; 673 goto restart; 674 } 675 } 676 error = ENOENT; 677fail: 678 ufsdirhash_release(dh); 679 if (bp != NULL) 680 brelse(bp); 681 return (error); 682} 683 684/* 685 * Find a directory block with room for 'slotneeded' bytes. Returns 686 * the offset of the directory entry that begins the free space. 687 * This will either be the offset of an existing entry that has free 688 * space at the end, or the offset of an entry with d_ino == 0 at 689 * the start of a DIRBLKSIZ block. 690 * 691 * To use the space, the caller may need to compact existing entries in 692 * the directory. The total number of bytes in all of the entries involved 693 * in the compaction is stored in *slotsize. In other words, all of 694 * the entries that must be compacted are exactly contained in the 695 * region beginning at the returned offset and spanning *slotsize bytes. 696 * 697 * Returns -1 if no space was found, indicating that the directory 698 * must be extended. 699 */ 700doff_t 701ufsdirhash_findfree(struct inode *ip, int slotneeded, int *slotsize) 702{ 703 struct direct *dp; 704 struct dirhash *dh; 705 struct buf *bp; 706 doff_t pos, slotstart; 707 int dirblock, error, freebytes, i; 708 709 dh = ip->i_dirhash; 710 KASSERT(dh != NULL && dh->dh_hash != NULL, 711 ("ufsdirhash_findfree: Invalid dirhash %p\n", dh)); 712 DIRHASH_ASSERT_LOCKED(dh); 713 714 /* Find a directory block with the desired free space. */ 715 dirblock = -1; 716 for (i = howmany(slotneeded, DIRALIGN); i <= DH_NFSTATS; i++) 717 if ((dirblock = dh->dh_firstfree[i]) != -1) 718 break; 719 if (dirblock == -1) 720 return (-1); 721 722 KASSERT(dirblock < dh->dh_nblk && 723 dh->dh_blkfree[dirblock] >= howmany(slotneeded, DIRALIGN), 724 ("ufsdirhash_findfree: bad stats")); 725 pos = dirblock * DIRBLKSIZ; 726 error = UFS_BLKATOFF(ip->i_vnode, (off_t)pos, (char **)&dp, &bp); 727 if (error) 728 return (-1); 729 730 /* Find the first entry with free space. */ 731 for (i = 0; i < DIRBLKSIZ; ) { 732 if (dp->d_reclen == 0) { 733 brelse(bp); 734 return (-1); 735 } 736 if (dp->d_ino == 0 || dp->d_reclen > DIRSIZ(0, dp)) 737 break; 738 i += dp->d_reclen; 739 dp = (struct direct *)((char *)dp + dp->d_reclen); 740 } 741 if (i > DIRBLKSIZ) { 742 brelse(bp); 743 return (-1); 744 } 745 slotstart = pos + i; 746 747 /* Find the range of entries needed to get enough space */ 748 freebytes = 0; 749 while (i < DIRBLKSIZ && freebytes < slotneeded) { 750 freebytes += dp->d_reclen; 751 if (dp->d_ino != 0) 752 freebytes -= DIRSIZ(0, dp); 753 if (dp->d_reclen == 0) { 754 brelse(bp); 755 return (-1); 756 } 757 i += dp->d_reclen; 758 dp = (struct direct *)((char *)dp + dp->d_reclen); 759 } 760 if (i > DIRBLKSIZ) { 761 brelse(bp); 762 return (-1); 763 } 764 if (freebytes < slotneeded) 765 panic("ufsdirhash_findfree: free mismatch"); 766 brelse(bp); 767 *slotsize = pos + i - slotstart; 768 return (slotstart); 769} 770 771/* 772 * Return the start of the unused space at the end of a directory, or 773 * -1 if there are no trailing unused blocks. 774 */ 775doff_t 776ufsdirhash_enduseful(struct inode *ip) 777{ 778 779 struct dirhash *dh; 780 int i; 781 782 dh = ip->i_dirhash; 783 DIRHASH_ASSERT_LOCKED(dh); 784 KASSERT(dh != NULL && dh->dh_hash != NULL, 785 ("ufsdirhash_enduseful: Invalid dirhash %p\n", dh)); 786 787 if (dh->dh_blkfree[dh->dh_dirblks - 1] != DIRBLKSIZ / DIRALIGN) 788 return (-1); 789 790 for (i = dh->dh_dirblks - 1; i >= 0; i--) 791 if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN) 792 break; 793 794 return ((doff_t)(i + 1) * DIRBLKSIZ); 795} 796 797/* 798 * Insert information into the hash about a new directory entry. dirp 799 * points to a struct direct containing the entry, and offset specifies 800 * the offset of this entry. 801 */ 802void 803ufsdirhash_add(struct inode *ip, struct direct *dirp, doff_t offset) 804{ 805 struct dirhash *dh; 806 int slot; 807 808 if ((dh = ufsdirhash_acquire(ip)) == NULL) 809 return; 810 811 KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ, 812 ("ufsdirhash_add: bad offset")); 813 /* 814 * Normal hash usage is < 66%. If the usage gets too high then 815 * remove the hash entirely and let it be rebuilt later. 816 */ 817 if (dh->dh_hused >= (dh->dh_hlen * 3) / 4) { 818 ufsdirhash_free_locked(ip); 819 return; 820 } 821 822 /* Find a free hash slot (empty or deleted), and add the entry. */ 823 slot = ufsdirhash_hash(dh, dirp->d_name, dirp->d_namlen); 824 while (DH_ENTRY(dh, slot) >= 0) 825 slot = WRAPINCR(slot, dh->dh_hlen); 826 if (DH_ENTRY(dh, slot) == DIRHASH_EMPTY) 827 dh->dh_hused++; 828 DH_ENTRY(dh, slot) = offset; 829 830 /* Update last used time. */ 831 dh->dh_lastused = time_second; 832 833 /* Update the per-block summary info. */ 834 ufsdirhash_adjfree(dh, offset, -DIRSIZ(0, dirp)); 835 ufsdirhash_release(dh); 836} 837 838/* 839 * Remove the specified directory entry from the hash. The entry to remove 840 * is defined by the name in `dirp', which must exist at the specified 841 * `offset' within the directory. 842 */ 843void 844ufsdirhash_remove(struct inode *ip, struct direct *dirp, doff_t offset) 845{ 846 struct dirhash *dh; 847 int slot; 848 849 if ((dh = ufsdirhash_acquire(ip)) == NULL) 850 return; 851 852 KASSERT(offset < dh->dh_dirblks * DIRBLKSIZ, 853 ("ufsdirhash_remove: bad offset")); 854 /* Find the entry */ 855 slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, offset); 856 857 /* Remove the hash entry. */ 858 ufsdirhash_delslot(dh, slot); 859 860 /* Update the per-block summary info. */ 861 ufsdirhash_adjfree(dh, offset, DIRSIZ(0, dirp)); 862 ufsdirhash_release(dh); 863} 864 865/* 866 * Change the offset associated with a directory entry in the hash. Used 867 * when compacting directory blocks. 868 */ 869void 870ufsdirhash_move(struct inode *ip, struct direct *dirp, doff_t oldoff, 871 doff_t newoff) 872{ 873 struct dirhash *dh; 874 int slot; 875 876 if ((dh = ufsdirhash_acquire(ip)) == NULL) 877 return; 878 879 KASSERT(oldoff < dh->dh_dirblks * DIRBLKSIZ && 880 newoff < dh->dh_dirblks * DIRBLKSIZ, 881 ("ufsdirhash_move: bad offset")); 882 /* Find the entry, and update the offset. */ 883 slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, oldoff); 884 DH_ENTRY(dh, slot) = newoff; 885 ufsdirhash_release(dh); 886} 887 888/* 889 * Inform dirhash that the directory has grown by one block that 890 * begins at offset (i.e. the new length is offset + DIRBLKSIZ). 891 */ 892void 893ufsdirhash_newblk(struct inode *ip, doff_t offset) 894{ 895 struct dirhash *dh; 896 int block; 897 898 if ((dh = ufsdirhash_acquire(ip)) == NULL) 899 return; 900 901 KASSERT(offset == dh->dh_dirblks * DIRBLKSIZ, 902 ("ufsdirhash_newblk: bad offset")); 903 block = offset / DIRBLKSIZ; 904 if (block >= dh->dh_nblk) { 905 /* Out of space; must rebuild. */ 906 ufsdirhash_free_locked(ip); 907 return; 908 } 909 dh->dh_dirblks = block + 1; 910 911 /* Account for the new free block. */ 912 dh->dh_blkfree[block] = DIRBLKSIZ / DIRALIGN; 913 if (dh->dh_firstfree[DH_NFSTATS] == -1) 914 dh->dh_firstfree[DH_NFSTATS] = block; 915 ufsdirhash_release(dh); 916} 917 918/* 919 * Inform dirhash that the directory is being truncated. 920 */ 921void 922ufsdirhash_dirtrunc(struct inode *ip, doff_t offset) 923{ 924 struct dirhash *dh; 925 int block, i; 926 927 if ((dh = ufsdirhash_acquire(ip)) == NULL) 928 return; 929 930 KASSERT(offset <= dh->dh_dirblks * DIRBLKSIZ, 931 ("ufsdirhash_dirtrunc: bad offset")); 932 block = howmany(offset, DIRBLKSIZ); 933 /* 934 * If the directory shrinks to less than 1/8 of dh_nblk blocks 935 * (about 20% of its original size due to the 50% extra added in 936 * ufsdirhash_build) then free it, and let the caller rebuild 937 * if necessary. 938 */ 939 if (block < dh->dh_nblk / 8 && dh->dh_narrays > 1) { 940 ufsdirhash_free_locked(ip); 941 return; 942 } 943 944 /* 945 * Remove any `first free' information pertaining to the 946 * truncated blocks. All blocks we're removing should be 947 * completely unused. 948 */ 949 if (dh->dh_firstfree[DH_NFSTATS] >= block) 950 dh->dh_firstfree[DH_NFSTATS] = -1; 951 for (i = block; i < dh->dh_dirblks; i++) 952 if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN) 953 panic("ufsdirhash_dirtrunc: blocks in use"); 954 for (i = 0; i < DH_NFSTATS; i++) 955 if (dh->dh_firstfree[i] >= block) 956 panic("ufsdirhash_dirtrunc: first free corrupt"); 957 dh->dh_dirblks = block; 958 ufsdirhash_release(dh); 959} 960 961/* 962 * Debugging function to check that the dirhash information about 963 * a directory block matches its actual contents. Panics if a mismatch 964 * is detected. 965 * 966 * On entry, `buf' should point to the start of an in-core 967 * DIRBLKSIZ-sized directory block, and `offset' should contain the 968 * offset from the start of the directory of that block. 969 */ 970void 971ufsdirhash_checkblock(struct inode *ip, char *buf, doff_t offset) 972{ 973 struct dirhash *dh; 974 struct direct *dp; 975 int block, ffslot, i, nfree; 976 977 if (!ufs_dirhashcheck) 978 return; 979 if ((dh = ufsdirhash_acquire(ip)) == NULL) 980 return; 981 982 block = offset / DIRBLKSIZ; 983 if ((offset & (DIRBLKSIZ - 1)) != 0 || block >= dh->dh_dirblks) 984 panic("ufsdirhash_checkblock: bad offset"); 985 986 nfree = 0; 987 for (i = 0; i < DIRBLKSIZ; i += dp->d_reclen) { 988 dp = (struct direct *)(buf + i); 989 if (dp->d_reclen == 0 || i + dp->d_reclen > DIRBLKSIZ) 990 panic("ufsdirhash_checkblock: bad dir"); 991 992 if (dp->d_ino == 0) { 993#if 0 994 /* 995 * XXX entries with d_ino == 0 should only occur 996 * at the start of a DIRBLKSIZ block. However the 997 * ufs code is tolerant of such entries at other 998 * offsets, and fsck does not fix them. 999 */ 1000 if (i != 0) 1001 panic("ufsdirhash_checkblock: bad dir inode"); 1002#endif 1003 nfree += dp->d_reclen; 1004 continue; 1005 } 1006 1007 /* Check that the entry exists (will panic if it doesn't). */ 1008 ufsdirhash_findslot(dh, dp->d_name, dp->d_namlen, offset + i); 1009 1010 nfree += dp->d_reclen - DIRSIZ(0, dp); 1011 } 1012 if (i != DIRBLKSIZ) 1013 panic("ufsdirhash_checkblock: bad dir end"); 1014 1015 if (dh->dh_blkfree[block] * DIRALIGN != nfree) 1016 panic("ufsdirhash_checkblock: bad free count"); 1017 1018 ffslot = BLKFREE2IDX(nfree / DIRALIGN); 1019 for (i = 0; i <= DH_NFSTATS; i++) 1020 if (dh->dh_firstfree[i] == block && i != ffslot) 1021 panic("ufsdirhash_checkblock: bad first-free"); 1022 if (dh->dh_firstfree[ffslot] == -1) 1023 panic("ufsdirhash_checkblock: missing first-free entry"); 1024 ufsdirhash_release(dh); 1025} 1026 1027/* 1028 * Hash the specified filename into a dirhash slot. 1029 */ 1030static int 1031ufsdirhash_hash(struct dirhash *dh, char *name, int namelen) 1032{ 1033 u_int32_t hash; 1034 1035 /* 1036 * We hash the name and then some other bit of data that is 1037 * invariant over the dirhash's lifetime. Otherwise names 1038 * differing only in the last byte are placed close to one 1039 * another in the table, which is bad for linear probing. 1040 */ 1041 hash = fnv_32_buf(name, namelen, FNV1_32_INIT); 1042 hash = fnv_32_buf(&dh, sizeof(dh), hash); 1043 return (hash % dh->dh_hlen); 1044} 1045 1046/* 1047 * Adjust the number of free bytes in the block containing `offset' 1048 * by the value specified by `diff'. 1049 * 1050 * The caller must ensure we have exclusive access to `dh'; normally 1051 * that means that dh_lock should be held, but this is also called 1052 * from ufsdirhash_build() where exclusive access can be assumed. 1053 */ 1054static void 1055ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff) 1056{ 1057 int block, i, nfidx, ofidx; 1058 1059 /* Update the per-block summary info. */ 1060 block = offset / DIRBLKSIZ; 1061 KASSERT(block < dh->dh_nblk && block < dh->dh_dirblks, 1062 ("dirhash bad offset")); 1063 ofidx = BLKFREE2IDX(dh->dh_blkfree[block]); 1064 dh->dh_blkfree[block] = (int)dh->dh_blkfree[block] + (diff / DIRALIGN); 1065 nfidx = BLKFREE2IDX(dh->dh_blkfree[block]); 1066 1067 /* Update the `first free' list if necessary. */ 1068 if (ofidx != nfidx) { 1069 /* If removing, scan forward for the next block. */ 1070 if (dh->dh_firstfree[ofidx] == block) { 1071 for (i = block + 1; i < dh->dh_dirblks; i++) 1072 if (BLKFREE2IDX(dh->dh_blkfree[i]) == ofidx) 1073 break; 1074 dh->dh_firstfree[ofidx] = (i < dh->dh_dirblks) ? i : -1; 1075 } 1076 1077 /* Make this the new `first free' if necessary */ 1078 if (dh->dh_firstfree[nfidx] > block || 1079 dh->dh_firstfree[nfidx] == -1) 1080 dh->dh_firstfree[nfidx] = block; 1081 } 1082} 1083 1084/* 1085 * Find the specified name which should have the specified offset. 1086 * Returns a slot number, and panics on failure. 1087 * 1088 * `dh' must be locked on entry and remains so on return. 1089 */ 1090static int 1091ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, doff_t offset) 1092{ 1093 int slot; 1094 1095 DIRHASH_ASSERT_LOCKED(dh); 1096 1097 /* Find the entry. */ 1098 KASSERT(dh->dh_hused < dh->dh_hlen, ("dirhash find full")); 1099 slot = ufsdirhash_hash(dh, name, namelen); 1100 while (DH_ENTRY(dh, slot) != offset && 1101 DH_ENTRY(dh, slot) != DIRHASH_EMPTY) 1102 slot = WRAPINCR(slot, dh->dh_hlen); 1103 if (DH_ENTRY(dh, slot) != offset) 1104 panic("ufsdirhash_findslot: '%.*s' not found", namelen, name); 1105 1106 return (slot); 1107} 1108 1109/* 1110 * Remove the entry corresponding to the specified slot from the hash array. 1111 * 1112 * `dh' must be locked on entry and remains so on return. 1113 */ 1114static void 1115ufsdirhash_delslot(struct dirhash *dh, int slot) 1116{ 1117 int i; 1118 1119 DIRHASH_ASSERT_LOCKED(dh); 1120 1121 /* Mark the entry as deleted. */ 1122 DH_ENTRY(dh, slot) = DIRHASH_DEL; 1123 1124 /* If this is the end of a chain of DIRHASH_DEL slots, remove them. */ 1125 for (i = slot; DH_ENTRY(dh, i) == DIRHASH_DEL; ) 1126 i = WRAPINCR(i, dh->dh_hlen); 1127 if (DH_ENTRY(dh, i) == DIRHASH_EMPTY) { 1128 i = WRAPDECR(i, dh->dh_hlen); 1129 while (DH_ENTRY(dh, i) == DIRHASH_DEL) { 1130 DH_ENTRY(dh, i) = DIRHASH_EMPTY; 1131 dh->dh_hused--; 1132 i = WRAPDECR(i, dh->dh_hlen); 1133 } 1134 KASSERT(dh->dh_hused >= 0, ("ufsdirhash_delslot neg hlen")); 1135 } 1136} 1137 1138/* 1139 * Given a directory entry and its offset, find the offset of the 1140 * previous entry in the same DIRBLKSIZ-sized block. Returns an 1141 * offset, or -1 if there is no previous entry in the block or some 1142 * other problem occurred. 1143 */ 1144static doff_t 1145ufsdirhash_getprev(struct direct *dirp, doff_t offset) 1146{ 1147 struct direct *dp; 1148 char *blkbuf; 1149 doff_t blkoff, prevoff; 1150 int entrypos, i; 1151 1152 blkoff = offset & ~(DIRBLKSIZ - 1); /* offset of start of block */ 1153 entrypos = offset & (DIRBLKSIZ - 1); /* entry relative to block */ 1154 blkbuf = (char *)dirp - entrypos; 1155 prevoff = blkoff; 1156 1157 /* If `offset' is the start of a block, there is no previous entry. */ 1158 if (entrypos == 0) 1159 return (-1); 1160 1161 /* Scan from the start of the block until we get to the entry. */ 1162 for (i = 0; i < entrypos; i += dp->d_reclen) { 1163 dp = (struct direct *)(blkbuf + i); 1164 if (dp->d_reclen == 0 || i + dp->d_reclen > entrypos) 1165 return (-1); /* Corrupted directory. */ 1166 prevoff = blkoff + i; 1167 } 1168 return (prevoff); 1169} 1170 1171/* 1172 * Delete the given dirhash and reclaim its memory. Assumes that 1173 * ufsdirhash_list is locked, and leaves it locked. Also assumes 1174 * that dh is locked. Returns the amount of memory freed. 1175 */ 1176static int 1177ufsdirhash_destroy(struct dirhash *dh) 1178{ 1179 doff_t **hash; 1180 u_int8_t *blkfree; 1181 int i, mem, narrays; 1182 1183 KASSERT(dh->dh_hash != NULL, ("dirhash: NULL hash on list")); 1184 1185 /* Remove it from the list and detach its memory. */ 1186 TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list); 1187 dh->dh_onlist = 0; 1188 hash = dh->dh_hash; 1189 dh->dh_hash = NULL; 1190 blkfree = dh->dh_blkfree; 1191 dh->dh_blkfree = NULL; 1192 narrays = dh->dh_narrays; 1193 mem = dh->dh_memreq; 1194 dh->dh_memreq = 0; 1195 1196 /* Unlock dirhash and free the detached memory. */ 1197 ufsdirhash_release(dh); 1198 for (i = 0; i < narrays; i++) 1199 DIRHASH_BLKFREE(hash[i]); 1200 free(hash, M_DIRHASH); 1201 free(blkfree, M_DIRHASH); 1202 1203 /* Account for the returned memory. */ 1204 ufs_dirhashmem -= mem; 1205 1206 return (mem); 1207} 1208 1209/* 1210 * Try to free up `wanted' bytes by stealing memory from existing 1211 * dirhashes. Returns zero with list locked if successful. 1212 */ 1213static int 1214ufsdirhash_recycle(int wanted) 1215{ 1216 struct dirhash *dh; 1217 1218 DIRHASHLIST_LOCK(); 1219 dh = TAILQ_FIRST(&ufsdirhash_list); 1220 while (wanted + ufs_dirhashmem > ufs_dirhashmaxmem) { 1221 /* Decrement the score; only recycle if it becomes zero. */ 1222 if (dh == NULL || --dh->dh_score > 0) { 1223 DIRHASHLIST_UNLOCK(); 1224 return (-1); 1225 } 1226 /* 1227 * If we can't lock it it's in use and we don't want to 1228 * recycle it anyway. 1229 */ 1230 if (!sx_try_xlock(&dh->dh_lock)) { 1231 dh = TAILQ_NEXT(dh, dh_list); 1232 continue; 1233 } 1234 1235 ufsdirhash_destroy(dh); 1236 1237 /* Repeat if necessary. */ 1238 dh = TAILQ_FIRST(&ufsdirhash_list); 1239 } 1240 /* Success; return with list locked. */ 1241 return (0); 1242} 1243 1244/* 1245 * Callback that frees some dirhashes when the system is low on virtual memory. 1246 */ 1247static void 1248ufsdirhash_lowmem() 1249{ 1250 struct dirhash *dh, *dh_temp; 1251 int memfreed, memwanted; 1252 1253 ufs_dirhashlowmemcount++; 1254 memfreed = 0; 1255 memwanted = ufs_dirhashmem * ufs_dirhashreclaimpercent / 100; 1256 1257 DIRHASHLIST_LOCK(); 1258 1259 /* 1260 * Reclaim up to memwanted from the oldest dirhashes. This will allow 1261 * us to make some progress when the system is running out of memory 1262 * without compromising the dinamicity of maximum age. If the situation 1263 * does not improve lowmem will be eventually retriggered and free some 1264 * other entry in the cache. The entries on the head of the list should 1265 * be the oldest. If during list traversal we can't get a lock on the 1266 * dirhash, it will be skipped. 1267 */ 1268 TAILQ_FOREACH_SAFE(dh, &ufsdirhash_list, dh_list, dh_temp) { 1269 if (sx_try_xlock(&dh->dh_lock)) 1270 memfreed += ufsdirhash_destroy(dh); 1271 if (memfreed >= memwanted) 1272 break; 1273 } 1274 DIRHASHLIST_UNLOCK(); 1275} 1276 1277static int 1278ufsdirhash_set_reclaimpercent(SYSCTL_HANDLER_ARGS) 1279{ 1280 int error, v; 1281 1282 v = ufs_dirhashreclaimpercent; 1283 error = sysctl_handle_int(oidp, &v, v, req); 1284 if (error) 1285 return (error); 1286 if (req->newptr == NULL) 1287 return (error); 1288 if (v == ufs_dirhashreclaimpercent) 1289 return (0); 1290 1291 /* Refuse invalid percentages */ 1292 if (v < 0 || v > 100) 1293 return (EINVAL); 1294 ufs_dirhashreclaimpercent = v; 1295 return (0); 1296} 1297 1298void 1299ufsdirhash_init() 1300{ 1301 ufs_dirhashmaxmem = lmax(roundup(hibufspace / 64, PAGE_SIZE), 1302 2 * 1024 * 1024); 1303 1304 ufsdirhash_zone = uma_zcreate("DIRHASH", DH_NBLKOFF * sizeof(doff_t), 1305 NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0); 1306 mtx_init(&ufsdirhash_mtx, "dirhash list", NULL, MTX_DEF); 1307 TAILQ_INIT(&ufsdirhash_list); 1308 1309 /* Register a callback function to handle low memory signals */ 1310 EVENTHANDLER_REGISTER(vm_lowmem, ufsdirhash_lowmem, NULL, 1311 EVENTHANDLER_PRI_FIRST); 1312} 1313 1314void 1315ufsdirhash_uninit() 1316{ 1317 KASSERT(TAILQ_EMPTY(&ufsdirhash_list), ("ufsdirhash_uninit")); 1318 uma_zdestroy(ufsdirhash_zone); 1319 mtx_destroy(&ufsdirhash_mtx); 1320} 1321 1322#endif /* UFS_DIRHASH */ 1323