Annotation of sys/ufs/ufs/ufs_dirhash.c, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: ufs_dirhash.c,v 1.15 2007/07/23 17:28:25 kettenis Exp $ */
2: /*
3: * Copyright (c) 2001, 2002 Ian Dowse. All rights reserved.
4: *
5: * Redistribution and use in source and binary forms, with or without
6: * modification, are permitted provided that the following conditions
7: * are met:
8: * 1. Redistributions of source code must retain the above copyright
9: * notice, this list of conditions and the following disclaimer.
10: * 2. Redistributions in binary form must reproduce the above copyright
11: * notice, this list of conditions and the following disclaimer in the
12: * documentation and/or other materials provided with the distribution.
13: *
14: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17: * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24: * SUCH DAMAGE.
25: */
26:
27: /*
28: * This implements a hash-based lookup scheme for UFS directories.
29: */
30:
31: #if 0
32: __FBSDID("$FreeBSD: src/sys/ufs/ufs/ufs_dirhash.c,v 1.18 2004/02/15 21:39:35 dwmalone Exp $");
33: #endif
34:
35: #include <sys/param.h>
36: #include <sys/systm.h>
37: #include <sys/kernel.h>
38: #include <sys/lock.h>
39: #include <sys/rwlock.h>
40: #include <sys/malloc.h>
41: #include <sys/pool.h>
42: #include <sys/proc.h>
43: #include <sys/buf.h>
44: #include <sys/vnode.h>
45: #include <sys/mount.h>
46: #include <sys/sysctl.h>
47: #include <sys/hash.h>
48:
49: #include <ufs/ufs/quota.h>
50: #include <ufs/ufs/inode.h>
51: #include <ufs/ufs/dir.h>
52: #include <ufs/ufs/dirhash.h>
53: #include <ufs/ufs/ufsmount.h>
54: #include <ufs/ufs/ufs_extern.h>
55:
56: #define WRAPINCR(val, limit) (((val) + 1 == (limit)) ? 0 : ((val) + 1))
57: #define WRAPDECR(val, limit) (((val) == 0) ? ((limit) - 1) : ((val) - 1))
58: #define OFSFMT(vp) ((vp)->v_mount->mnt_maxsymlinklen <= 0)
59: #define BLKFREE2IDX(n) ((n) > DH_NFSTATS ? DH_NFSTATS : (n))
60:
61: int ufs_mindirhashsize;
62: int ufs_dirhashmaxmem;
63: int ufs_dirhashmem;
64: int ufs_dirhashcheck;
65:
66:
67: int ufsdirhash_hash(struct dirhash *dh, char *name, int namelen);
68: void ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff);
69: void ufsdirhash_delslot(struct dirhash *dh, int slot);
70: int ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen,
71: doff_t offset);
72: doff_t ufsdirhash_getprev(struct direct *dp, doff_t offset);
73: int ufsdirhash_recycle(int wanted);
74:
75: struct pool ufsdirhash_pool;
76:
77: #define DIRHASHLIST_LOCK()
78: #define DIRHASHLIST_UNLOCK()
79: #define DIRHASH_LOCK(dh)
80: #define DIRHASH_UNLOCK(dh)
81: #define DIRHASH_BLKALLOC() pool_get(&ufsdirhash_pool, PR_NOWAIT)
82: #define DIRHASH_BLKFREE(v) pool_put(&ufsdirhash_pool, v)
83:
84: #define mtx_assert(l, f) /* nothing */
85: #define DIRHASH_ASSERT(e, m) KASSERT((e))
86:
87: /* Dirhash list; recently-used entries are near the tail. */
88: TAILQ_HEAD(, dirhash) ufsdirhash_list;
89:
90: /* Protects: ufsdirhash_list, `dh_list' field, ufs_dirhashmem. */
91:
92: /*
93: * Locking order:
94: * ufsdirhash_mtx
95: * dh_mtx
96: *
97: * The dh_mtx mutex should be acquired either via the inode lock, or via
98: * ufsdirhash_mtx. Only the owner of the inode may free the associated
99: * dirhash, but anything can steal its memory and set dh_hash to NULL.
100: */
101:
102: /*
103: * Attempt to build up a hash table for the directory contents in
104: * inode 'ip'. Returns 0 on success, or -1 of the operation failed.
105: */
106: int
107: ufsdirhash_build(struct inode *ip)
108: {
109: struct dirhash *dh;
110: struct buf *bp = NULL;
111: struct direct *ep;
112: struct vnode *vp;
113: doff_t bmask, pos;
114: int dirblocks, i, j, memreqd, nblocks, narrays, nslots, slot;
115:
116: /* Check if we can/should use dirhash. */
117: if (ip->i_dirhash == NULL) {
118: if (DIP(ip, size) < ufs_mindirhashsize || OFSFMT(ip->i_vnode))
119: return (-1);
120: } else {
121: /* Hash exists, but sysctls could have changed. */
122: if (DIP(ip, size) < ufs_mindirhashsize ||
123: ufs_dirhashmem > ufs_dirhashmaxmem) {
124: ufsdirhash_free(ip);
125: return (-1);
126: }
127: /* Check if hash exists and is intact (note: unlocked read). */
128: if (ip->i_dirhash->dh_hash != NULL)
129: return (0);
130: /* Free the old, recycled hash and build a new one. */
131: ufsdirhash_free(ip);
132: }
133:
134: /* Don't hash removed directories. */
135: if (ip->i_effnlink == 0)
136: return (-1);
137:
138: vp = ip->i_vnode;
139: /* Allocate 50% more entries than this dir size could ever need. */
140: DIRHASH_ASSERT(DIP(ip, size) >= DIRBLKSIZ, ("ufsdirhash_build size"));
141: nslots = DIP(ip, size) / DIRECTSIZ(1);
142: nslots = (nslots * 3 + 1) / 2;
143: narrays = howmany(nslots, DH_NBLKOFF);
144: nslots = narrays * DH_NBLKOFF;
145: dirblocks = howmany(DIP(ip, size), DIRBLKSIZ);
146: nblocks = (dirblocks * 3 + 1) / 2;
147:
148: memreqd = sizeof(*dh) + narrays * sizeof(*dh->dh_hash) +
149: narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) +
150: nblocks * sizeof(*dh->dh_blkfree);
151: DIRHASHLIST_LOCK();
152: if (memreqd + ufs_dirhashmem > ufs_dirhashmaxmem) {
153: DIRHASHLIST_UNLOCK();
154: if (memreqd > ufs_dirhashmaxmem / 2)
155: return (-1);
156:
157: /* Try to free some space. */
158: if (ufsdirhash_recycle(memreqd) != 0)
159: return (-1);
160: /* Enough was freed, and list has been locked. */
161: }
162: ufs_dirhashmem += memreqd;
163: DIRHASHLIST_UNLOCK();
164:
165: /*
166: * Use non-blocking mallocs so that we will revert to a linear
167: * lookup on failure rather than potentially blocking forever.
168: */
169: MALLOC(dh, struct dirhash *, sizeof *dh, M_DIRHASH, M_NOWAIT);
170: if (dh == NULL) {
171: DIRHASHLIST_LOCK();
172: ufs_dirhashmem -= memreqd;
173: DIRHASHLIST_UNLOCK();
174: return (-1);
175: }
176: memset(dh, 0, sizeof *dh);
177: dh->dh_hash = malloc(narrays * sizeof(dh->dh_hash[0]),
178: M_DIRHASH, M_NOWAIT);
179: dh->dh_blkfree = malloc(nblocks * sizeof(dh->dh_blkfree[0]),
180: M_DIRHASH, M_NOWAIT);
181: if (dh->dh_hash == NULL || dh->dh_blkfree == NULL)
182: goto fail;
183: memset(dh->dh_hash, 0, narrays * sizeof(dh->dh_hash[0]));
184: for (i = 0; i < narrays; i++) {
185: if ((dh->dh_hash[i] = DIRHASH_BLKALLOC()) == NULL)
186: goto fail;
187: for (j = 0; j < DH_NBLKOFF; j++)
188: dh->dh_hash[i][j] = DIRHASH_EMPTY;
189: }
190:
191: /* Initialise the hash table and block statistics. */
192: dh->dh_narrays = narrays;
193: dh->dh_hlen = nslots;
194: dh->dh_nblk = nblocks;
195: dh->dh_dirblks = dirblocks;
196: for (i = 0; i < dirblocks; i++)
197: dh->dh_blkfree[i] = DIRBLKSIZ / DIRALIGN;
198: for (i = 0; i < DH_NFSTATS; i++)
199: dh->dh_firstfree[i] = -1;
200: dh->dh_firstfree[DH_NFSTATS] = 0;
201: dh->dh_seqopt = 0;
202: dh->dh_seqoff = 0;
203: dh->dh_score = DH_SCOREINIT;
204: ip->i_dirhash = dh;
205:
206: bmask = VFSTOUFS(vp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
207: pos = 0;
208: while (pos < DIP(ip, size)) {
209: /* If necessary, get the next directory block. */
210: if ((pos & bmask) == 0) {
211: if (bp != NULL)
212: brelse(bp);
213: if (UFS_BUFATOFF(ip, (off_t)pos, NULL, &bp) != 0)
214: goto fail;
215: }
216:
217: /* Add this entry to the hash. */
218: ep = (struct direct *)((char *)bp->b_data + (pos & bmask));
219: if (ep->d_reclen == 0 || ep->d_reclen >
220: DIRBLKSIZ - (pos & (DIRBLKSIZ - 1))) {
221: /* Corrupted directory. */
222: brelse(bp);
223: goto fail;
224: }
225: if (ep->d_ino != 0) {
226: /* Add the entry (simplified ufsdirhash_add). */
227: slot = ufsdirhash_hash(dh, ep->d_name, ep->d_namlen);
228: while (DH_ENTRY(dh, slot) != DIRHASH_EMPTY)
229: slot = WRAPINCR(slot, dh->dh_hlen);
230: dh->dh_hused++;
231: DH_ENTRY(dh, slot) = pos;
232: ufsdirhash_adjfree(dh, pos, -DIRSIZ(0, ep));
233: }
234: pos += ep->d_reclen;
235: }
236:
237: if (bp != NULL)
238: brelse(bp);
239: DIRHASHLIST_LOCK();
240: TAILQ_INSERT_TAIL(&ufsdirhash_list, dh, dh_list);
241: dh->dh_onlist = 1;
242: DIRHASHLIST_UNLOCK();
243: return (0);
244:
245: fail:
246: if (dh->dh_hash != NULL) {
247: for (i = 0; i < narrays; i++)
248: if (dh->dh_hash[i] != NULL)
249: DIRHASH_BLKFREE(dh->dh_hash[i]);
250: free(dh->dh_hash, M_DIRHASH);
251: }
252: if (dh->dh_blkfree != NULL)
253: free(dh->dh_blkfree, M_DIRHASH);
254: FREE(dh, M_DIRHASH);
255: ip->i_dirhash = NULL;
256: DIRHASHLIST_LOCK();
257: ufs_dirhashmem -= memreqd;
258: DIRHASHLIST_UNLOCK();
259: return (-1);
260: }
261:
262: /*
263: * Free any hash table associated with inode 'ip'.
264: */
265: void
266: ufsdirhash_free(struct inode *ip)
267: {
268: struct dirhash *dh;
269: int i, mem;
270:
271: if ((dh = ip->i_dirhash) == NULL)
272: return;
273: DIRHASHLIST_LOCK();
274: DIRHASH_LOCK(dh);
275: if (dh->dh_onlist)
276: TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list);
277: DIRHASH_UNLOCK(dh);
278: DIRHASHLIST_UNLOCK();
279:
280: /* The dirhash pointed to by 'dh' is exclusively ours now. */
281:
282: mem = sizeof(*dh);
283: if (dh->dh_hash != NULL) {
284: for (i = 0; i < dh->dh_narrays; i++)
285: DIRHASH_BLKFREE(dh->dh_hash[i]);
286: free(dh->dh_hash, M_DIRHASH);
287: free(dh->dh_blkfree, M_DIRHASH);
288: mem += dh->dh_narrays * sizeof(*dh->dh_hash) +
289: dh->dh_narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) +
290: dh->dh_nblk * sizeof(*dh->dh_blkfree);
291: }
292: FREE(dh, M_DIRHASH);
293: ip->i_dirhash = NULL;
294:
295: DIRHASHLIST_LOCK();
296: ufs_dirhashmem -= mem;
297: DIRHASHLIST_UNLOCK();
298: }
299:
300: /*
301: * Find the offset of the specified name within the given inode.
302: * Returns 0 on success, ENOENT if the entry does not exist, or
303: * EJUSTRETURN if the caller should revert to a linear search.
304: *
305: * If successful, the directory offset is stored in *offp, and a
306: * pointer to a struct buf containing the entry is stored in *bpp. If
307: * prevoffp is non-NULL, the offset of the previous entry within
308: * the DIRBLKSIZ-sized block is stored in *prevoffp (if the entry
309: * is the first in a block, the start of the block is used).
310: */
311: int
312: ufsdirhash_lookup(struct inode *ip, char *name, int namelen, doff_t *offp,
313: struct buf **bpp, doff_t *prevoffp)
314: {
315: struct dirhash *dh, *dh_next;
316: struct direct *dp;
317: struct vnode *vp;
318: struct buf *bp;
319: doff_t blkoff, bmask, offset, prevoff;
320: int i, slot;
321:
322: if ((dh = ip->i_dirhash) == NULL)
323: return (EJUSTRETURN);
324: /*
325: * Move this dirhash towards the end of the list if it has a
326: * score higher than the next entry, and acquire the dh_mtx.
327: * Optimise the case where it's already the last by performing
328: * an unlocked read of the TAILQ_NEXT pointer.
329: *
330: * In both cases, end up holding just dh_mtx.
331: */
332: if (TAILQ_NEXT(dh, dh_list) != NULL) {
333: DIRHASHLIST_LOCK();
334: DIRHASH_LOCK(dh);
335: /*
336: * If the new score will be greater than that of the next
337: * entry, then move this entry past it. With both mutexes
338: * held, dh_next won't go away, but its dh_score could
339: * change; that's not important since it is just a hint.
340: */
341: if (dh->dh_hash != NULL &&
342: (dh_next = TAILQ_NEXT(dh, dh_list)) != NULL &&
343: dh->dh_score >= dh_next->dh_score) {
344: DIRHASH_ASSERT(dh->dh_onlist, ("dirhash: not on list"));
345: TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list);
346: TAILQ_INSERT_AFTER(&ufsdirhash_list, dh_next, dh,
347: dh_list);
348: }
349: DIRHASHLIST_UNLOCK();
350: } else {
351: /* Already the last, though that could change as we wait. */
352: DIRHASH_LOCK(dh);
353: }
354: if (dh->dh_hash == NULL) {
355: DIRHASH_UNLOCK(dh);
356: ufsdirhash_free(ip);
357: return (EJUSTRETURN);
358: }
359:
360: /* Update the score. */
361: if (dh->dh_score < DH_SCOREMAX)
362: dh->dh_score++;
363:
364: vp = ip->i_vnode;
365: bmask = VFSTOUFS(vp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
366: blkoff = -1;
367: bp = NULL;
368: restart:
369: slot = ufsdirhash_hash(dh, name, namelen);
370:
371: if (dh->dh_seqopt) {
372: /*
373: * Sequential access optimisation. dh_seqoff contains the
374: * offset of the directory entry immediately following
375: * the last entry that was looked up. Check if this offset
376: * appears in the hash chain for the name we are looking for.
377: */
378: for (i = slot; (offset = DH_ENTRY(dh, i)) != DIRHASH_EMPTY;
379: i = WRAPINCR(i, dh->dh_hlen))
380: if (offset == dh->dh_seqoff)
381: break;
382: if (offset == dh->dh_seqoff) {
383: /*
384: * We found an entry with the expected offset. This
385: * is probably the entry we want, but if not, the
386: * code below will turn off seqoff and retry.
387: */
388: slot = i;
389: } else
390: dh->dh_seqopt = 0;
391: }
392:
393: for (; (offset = DH_ENTRY(dh, slot)) != DIRHASH_EMPTY;
394: slot = WRAPINCR(slot, dh->dh_hlen)) {
395: if (offset == DIRHASH_DEL)
396: continue;
397: DIRHASH_UNLOCK(dh);
398:
399: if (offset < 0 || offset >= DIP(ip, size))
400: panic("ufsdirhash_lookup: bad offset in hash array");
401: if ((offset & ~bmask) != blkoff) {
402: if (bp != NULL)
403: brelse(bp);
404: blkoff = offset & ~bmask;
405: if (UFS_BUFATOFF(ip, (off_t)blkoff, NULL, &bp) != 0)
406: return (EJUSTRETURN);
407: }
408: dp = (struct direct *)(bp->b_data + (offset & bmask));
409: if (dp->d_reclen == 0 || dp->d_reclen >
410: DIRBLKSIZ - (offset & (DIRBLKSIZ - 1))) {
411: /* Corrupted directory. */
412: brelse(bp);
413: return (EJUSTRETURN);
414: }
415: if (dp->d_namlen == namelen &&
416: bcmp(dp->d_name, name, namelen) == 0) {
417: /* Found. Get the prev offset if needed. */
418: if (prevoffp != NULL) {
419: if (offset & (DIRBLKSIZ - 1)) {
420: prevoff = ufsdirhash_getprev(dp,
421: offset);
422: if (prevoff == -1) {
423: brelse(bp);
424: return (EJUSTRETURN);
425: }
426: } else
427: prevoff = offset;
428: *prevoffp = prevoff;
429: }
430:
431: /* Check for sequential access, and update offset. */
432: if (dh->dh_seqopt == 0 && dh->dh_seqoff == offset)
433: dh->dh_seqopt = 1;
434: dh->dh_seqoff = offset + DIRSIZ(0, dp);
435:
436: *bpp = bp;
437: *offp = offset;
438: return (0);
439: }
440:
441: DIRHASH_LOCK(dh);
442: if (dh->dh_hash == NULL) {
443: DIRHASH_UNLOCK(dh);
444: if (bp != NULL)
445: brelse(bp);
446: ufsdirhash_free(ip);
447: return (EJUSTRETURN);
448: }
449: /*
450: * When the name doesn't match in the seqopt case, go back
451: * and search normally.
452: */
453: if (dh->dh_seqopt) {
454: dh->dh_seqopt = 0;
455: goto restart;
456: }
457: }
458: DIRHASH_UNLOCK(dh);
459: if (bp != NULL)
460: brelse(bp);
461: return (ENOENT);
462: }
463:
464: /*
465: * Find a directory block with room for 'slotneeded' bytes. Returns
466: * the offset of the directory entry that begins the free space.
467: * This will either be the offset of an existing entry that has free
468: * space at the end, or the offset of an entry with d_ino == 0 at
469: * the start of a DIRBLKSIZ block.
470: *
471: * To use the space, the caller may need to compact existing entries in
472: * the directory. The total number of bytes in all of the entries involved
473: * in the compaction is stored in *slotsize. In other words, all of
474: * the entries that must be compacted are exactly contained in the
475: * region beginning at the returned offset and spanning *slotsize bytes.
476: *
477: * Returns -1 if no space was found, indicating that the directory
478: * must be extended.
479: */
480: doff_t
481: ufsdirhash_findfree(struct inode *ip, int slotneeded, int *slotsize)
482: {
483: struct direct *dp;
484: struct dirhash *dh;
485: struct buf *bp;
486: doff_t pos, slotstart;
487: int dirblock, error, freebytes, i;
488:
489: if ((dh = ip->i_dirhash) == NULL)
490: return (-1);
491: DIRHASH_LOCK(dh);
492: if (dh->dh_hash == NULL) {
493: DIRHASH_UNLOCK(dh);
494: ufsdirhash_free(ip);
495: return (-1);
496: }
497:
498: /* Find a directory block with the desired free space. */
499: dirblock = -1;
500: for (i = howmany(slotneeded, DIRALIGN); i <= DH_NFSTATS; i++)
501: if ((dirblock = dh->dh_firstfree[i]) != -1)
502: break;
503: if (dirblock == -1) {
504: DIRHASH_UNLOCK(dh);
505: return (-1);
506: }
507:
508: DIRHASH_ASSERT(dirblock < dh->dh_nblk &&
509: dh->dh_blkfree[dirblock] >= howmany(slotneeded, DIRALIGN),
510: ("ufsdirhash_findfree: bad stats"));
511: DIRHASH_UNLOCK(dh);
512: pos = dirblock * DIRBLKSIZ;
513: error = UFS_BUFATOFF(ip, (off_t)pos, (char **)&dp, &bp);
514: if (error)
515: return (-1);
516:
517: /* Find the first entry with free space. */
518: for (i = 0; i < DIRBLKSIZ; ) {
519: if (dp->d_reclen == 0) {
520: brelse(bp);
521: return (-1);
522: }
523: if (dp->d_ino == 0 || dp->d_reclen > DIRSIZ(0, dp))
524: break;
525: i += dp->d_reclen;
526: dp = (struct direct *)((char *)dp + dp->d_reclen);
527: }
528: if (i > DIRBLKSIZ) {
529: brelse(bp);
530: return (-1);
531: }
532: slotstart = pos + i;
533:
534: /* Find the range of entries needed to get enough space */
535: freebytes = 0;
536: while (i < DIRBLKSIZ && freebytes < slotneeded) {
537: freebytes += dp->d_reclen;
538: if (dp->d_ino != 0)
539: freebytes -= DIRSIZ(0, dp);
540: if (dp->d_reclen == 0) {
541: brelse(bp);
542: return (-1);
543: }
544: i += dp->d_reclen;
545: dp = (struct direct *)((char *)dp + dp->d_reclen);
546: }
547: if (i > DIRBLKSIZ) {
548: brelse(bp);
549: return (-1);
550: }
551: if (freebytes < slotneeded)
552: panic("ufsdirhash_findfree: free mismatch");
553: brelse(bp);
554: *slotsize = pos + i - slotstart;
555: return (slotstart);
556: }
557:
558: /*
559: * Return the start of the unused space at the end of a directory, or
560: * -1 if there are no trailing unused blocks.
561: */
562: doff_t
563: ufsdirhash_enduseful(struct inode *ip)
564: {
565:
566: struct dirhash *dh;
567: int i;
568:
569: if ((dh = ip->i_dirhash) == NULL)
570: return (-1);
571: DIRHASH_LOCK(dh);
572: if (dh->dh_hash == NULL) {
573: DIRHASH_UNLOCK(dh);
574: ufsdirhash_free(ip);
575: return (-1);
576: }
577:
578: if (dh->dh_blkfree[dh->dh_dirblks - 1] != DIRBLKSIZ / DIRALIGN) {
579: DIRHASH_UNLOCK(dh);
580: return (-1);
581: }
582:
583: for (i = dh->dh_dirblks - 1; i >= 0; i--)
584: if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN)
585: break;
586: DIRHASH_UNLOCK(dh);
587: return ((doff_t)(i + 1) * DIRBLKSIZ);
588: }
589:
590: /*
591: * Insert information into the hash about a new directory entry. dirp
592: * points to a struct direct containing the entry, and offset specifies
593: * the offset of this entry.
594: */
595: void
596: ufsdirhash_add(struct inode *ip, struct direct *dirp, doff_t offset)
597: {
598: struct dirhash *dh;
599: int slot;
600:
601: if ((dh = ip->i_dirhash) == NULL)
602: return;
603: DIRHASH_LOCK(dh);
604: if (dh->dh_hash == NULL) {
605: DIRHASH_UNLOCK(dh);
606: ufsdirhash_free(ip);
607: return;
608: }
609:
610: DIRHASH_ASSERT(offset < dh->dh_dirblks * DIRBLKSIZ,
611: ("ufsdirhash_add: bad offset"));
612: /*
613: * Normal hash usage is < 66%. If the usage gets too high then
614: * remove the hash entirely and let it be rebuilt later.
615: */
616: if (dh->dh_hused >= (dh->dh_hlen * 3) / 4) {
617: DIRHASH_UNLOCK(dh);
618: ufsdirhash_free(ip);
619: return;
620: }
621:
622: /* Find a free hash slot (empty or deleted), and add the entry. */
623: slot = ufsdirhash_hash(dh, dirp->d_name, dirp->d_namlen);
624: while (DH_ENTRY(dh, slot) >= 0)
625: slot = WRAPINCR(slot, dh->dh_hlen);
626: if (DH_ENTRY(dh, slot) == DIRHASH_EMPTY)
627: dh->dh_hused++;
628: DH_ENTRY(dh, slot) = offset;
629:
630: /* Update the per-block summary info. */
631: ufsdirhash_adjfree(dh, offset, -DIRSIZ(0, dirp));
632: DIRHASH_UNLOCK(dh);
633: }
634:
635: /*
636: * Remove the specified directory entry from the hash. The entry to remove
637: * is defined by the name in `dirp', which must exist at the specified
638: * `offset' within the directory.
639: */
640: void
641: ufsdirhash_remove(struct inode *ip, struct direct *dirp, doff_t offset)
642: {
643: struct dirhash *dh;
644: int slot;
645:
646: if ((dh = ip->i_dirhash) == NULL)
647: return;
648: DIRHASH_LOCK(dh);
649: if (dh->dh_hash == NULL) {
650: DIRHASH_UNLOCK(dh);
651: ufsdirhash_free(ip);
652: return;
653: }
654:
655: DIRHASH_ASSERT(offset < dh->dh_dirblks * DIRBLKSIZ,
656: ("ufsdirhash_remove: bad offset"));
657: /* Find the entry */
658: slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, offset);
659:
660: /* Remove the hash entry. */
661: ufsdirhash_delslot(dh, slot);
662:
663: /* Update the per-block summary info. */
664: ufsdirhash_adjfree(dh, offset, DIRSIZ(0, dirp));
665: DIRHASH_UNLOCK(dh);
666: }
667:
668: /*
669: * Change the offset associated with a directory entry in the hash. Used
670: * when compacting directory blocks.
671: */
672: void
673: ufsdirhash_move(struct inode *ip, struct direct *dirp, doff_t oldoff,
674: doff_t newoff)
675: {
676: struct dirhash *dh;
677: int slot;
678:
679: if ((dh = ip->i_dirhash) == NULL)
680: return;
681: DIRHASH_LOCK(dh);
682: if (dh->dh_hash == NULL) {
683: DIRHASH_UNLOCK(dh);
684: ufsdirhash_free(ip);
685: return;
686: }
687:
688: DIRHASH_ASSERT(oldoff < dh->dh_dirblks * DIRBLKSIZ &&
689: newoff < dh->dh_dirblks * DIRBLKSIZ,
690: ("ufsdirhash_move: bad offset"));
691: /* Find the entry, and update the offset. */
692: slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, oldoff);
693: DH_ENTRY(dh, slot) = newoff;
694: DIRHASH_UNLOCK(dh);
695: }
696:
697: /*
698: * Inform dirhash that the directory has grown by one block that
699: * begins at offset (i.e. the new length is offset + DIRBLKSIZ).
700: */
701: void
702: ufsdirhash_newblk(struct inode *ip, doff_t offset)
703: {
704: struct dirhash *dh;
705: int block;
706:
707: if ((dh = ip->i_dirhash) == NULL)
708: return;
709: DIRHASH_LOCK(dh);
710: if (dh->dh_hash == NULL) {
711: DIRHASH_UNLOCK(dh);
712: ufsdirhash_free(ip);
713: return;
714: }
715:
716: DIRHASH_ASSERT(offset == dh->dh_dirblks * DIRBLKSIZ,
717: ("ufsdirhash_newblk: bad offset"));
718: block = offset / DIRBLKSIZ;
719: if (block >= dh->dh_nblk) {
720: /* Out of space; must rebuild. */
721: DIRHASH_UNLOCK(dh);
722: ufsdirhash_free(ip);
723: return;
724: }
725: dh->dh_dirblks = block + 1;
726:
727: /* Account for the new free block. */
728: dh->dh_blkfree[block] = DIRBLKSIZ / DIRALIGN;
729: if (dh->dh_firstfree[DH_NFSTATS] == -1)
730: dh->dh_firstfree[DH_NFSTATS] = block;
731: DIRHASH_UNLOCK(dh);
732: }
733:
734: /*
735: * Inform dirhash that the directory is being truncated.
736: */
737: void
738: ufsdirhash_dirtrunc(struct inode *ip, doff_t offset)
739: {
740: struct dirhash *dh;
741: int block, i;
742:
743: if ((dh = ip->i_dirhash) == NULL)
744: return;
745: DIRHASH_LOCK(dh);
746: if (dh->dh_hash == NULL) {
747: DIRHASH_UNLOCK(dh);
748: ufsdirhash_free(ip);
749: return;
750: }
751:
752: DIRHASH_ASSERT(offset <= dh->dh_dirblks * DIRBLKSIZ,
753: ("ufsdirhash_dirtrunc: bad offset"));
754: block = howmany(offset, DIRBLKSIZ);
755: /*
756: * If the directory shrinks to less than 1/8 of dh_nblk blocks
757: * (about 20% of its original size due to the 50% extra added in
758: * ufsdirhash_build) then free it, and let the caller rebuild
759: * if necessary.
760: */
761: if (block < dh->dh_nblk / 8 && dh->dh_narrays > 1) {
762: DIRHASH_UNLOCK(dh);
763: ufsdirhash_free(ip);
764: return;
765: }
766:
767: /*
768: * Remove any `first free' information pertaining to the
769: * truncated blocks. All blocks we're removing should be
770: * completely unused.
771: */
772: if (dh->dh_firstfree[DH_NFSTATS] >= block)
773: dh->dh_firstfree[DH_NFSTATS] = -1;
774: for (i = block; i < dh->dh_dirblks; i++)
775: if (dh->dh_blkfree[i] != DIRBLKSIZ / DIRALIGN)
776: panic("ufsdirhash_dirtrunc: blocks in use");
777: for (i = 0; i < DH_NFSTATS; i++)
778: if (dh->dh_firstfree[i] >= block)
779: panic("ufsdirhash_dirtrunc: first free corrupt");
780: dh->dh_dirblks = block;
781: DIRHASH_UNLOCK(dh);
782: }
783:
784: /*
785: * Debugging function to check that the dirhash information about
786: * a directory block matches its actual contents. Panics if a mismatch
787: * is detected.
788: *
789: * On entry, `buf' should point to the start of an in-core
790: * DIRBLKSIZ-sized directory block, and `offset' should contain the
791: * offset from the start of the directory of that block.
792: */
793: void
794: ufsdirhash_checkblock(struct inode *ip, char *buf, doff_t offset)
795: {
796: struct dirhash *dh;
797: struct direct *dp;
798: int block, ffslot, i, nfree;
799:
800: if (!ufs_dirhashcheck)
801: return;
802: if ((dh = ip->i_dirhash) == NULL)
803: return;
804: DIRHASH_LOCK(dh);
805: if (dh->dh_hash == NULL) {
806: DIRHASH_UNLOCK(dh);
807: ufsdirhash_free(ip);
808: return;
809: }
810:
811: block = offset / DIRBLKSIZ;
812: if ((offset & (DIRBLKSIZ - 1)) != 0 || block >= dh->dh_dirblks)
813: panic("ufsdirhash_checkblock: bad offset");
814:
815: nfree = 0;
816: for (i = 0; i < DIRBLKSIZ; i += dp->d_reclen) {
817: dp = (struct direct *)(buf + i);
818: if (dp->d_reclen == 0 || i + dp->d_reclen > DIRBLKSIZ)
819: panic("ufsdirhash_checkblock: bad dir");
820:
821: if (dp->d_ino == 0) {
822: #if 0
823: /*
824: * XXX entries with d_ino == 0 should only occur
825: * at the start of a DIRBLKSIZ block. However the
826: * ufs code is tolerant of such entries at other
827: * offsets, and fsck does not fix them.
828: */
829: if (i != 0)
830: panic("ufsdirhash_checkblock: bad dir inode");
831: #endif
832: nfree += dp->d_reclen;
833: continue;
834: }
835:
836: /* Check that the entry exists (will panic if it doesn't). */
837: ufsdirhash_findslot(dh, dp->d_name, dp->d_namlen, offset + i);
838:
839: nfree += dp->d_reclen - DIRSIZ(0, dp);
840: }
841: if (i != DIRBLKSIZ)
842: panic("ufsdirhash_checkblock: bad dir end");
843:
844: if (dh->dh_blkfree[block] * DIRALIGN != nfree)
845: panic("ufsdirhash_checkblock: bad free count");
846:
847: ffslot = BLKFREE2IDX(nfree / DIRALIGN);
848: for (i = 0; i <= DH_NFSTATS; i++)
849: if (dh->dh_firstfree[i] == block && i != ffslot)
850: panic("ufsdirhash_checkblock: bad first-free");
851: if (dh->dh_firstfree[ffslot] == -1)
852: panic("ufsdirhash_checkblock: missing first-free entry");
853: DIRHASH_UNLOCK(dh);
854: }
855:
856: /*
857: * Hash the specified filename into a dirhash slot.
858: */
859: int
860: ufsdirhash_hash(struct dirhash *dh, char *name, int namelen)
861: {
862: u_int32_t hash;
863:
864: /*
865: * We hash the name and then some other bit of data that is
866: * invariant over the dirhash's lifetime. Otherwise names
867: * differing only in the last byte are placed close to one
868: * another in the table, which is bad for linear probing.
869: */
870: hash = hash32_buf(name, namelen, HASHINIT);
871: hash = hash32_buf(&dh, sizeof(dh), hash);
872: return (hash % dh->dh_hlen);
873: }
874:
875: /*
876: * Adjust the number of free bytes in the block containing `offset'
877: * by the value specified by `diff'.
878: *
879: * The caller must ensure we have exclusive access to `dh'; normally
880: * that means that dh_mtx should be held, but this is also called
881: * from ufsdirhash_build() where exclusive access can be assumed.
882: */
883: void
884: ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff)
885: {
886: int block, i, nfidx, ofidx;
887:
888: /* Update the per-block summary info. */
889: block = offset / DIRBLKSIZ;
890: DIRHASH_ASSERT(block < dh->dh_nblk && block < dh->dh_dirblks,
891: ("dirhash bad offset"));
892: ofidx = BLKFREE2IDX(dh->dh_blkfree[block]);
893: dh->dh_blkfree[block] = (int)dh->dh_blkfree[block] + (diff / DIRALIGN);
894: nfidx = BLKFREE2IDX(dh->dh_blkfree[block]);
895:
896: /* Update the `first free' list if necessary. */
897: if (ofidx != nfidx) {
898: /* If removing, scan forward for the next block. */
899: if (dh->dh_firstfree[ofidx] == block) {
900: for (i = block + 1; i < dh->dh_dirblks; i++)
901: if (BLKFREE2IDX(dh->dh_blkfree[i]) == ofidx)
902: break;
903: dh->dh_firstfree[ofidx] = (i < dh->dh_dirblks) ? i : -1;
904: }
905:
906: /* Make this the new `first free' if necessary */
907: if (dh->dh_firstfree[nfidx] > block ||
908: dh->dh_firstfree[nfidx] == -1)
909: dh->dh_firstfree[nfidx] = block;
910: }
911: }
912:
913: /*
914: * Find the specified name which should have the specified offset.
915: * Returns a slot number, and panics on failure.
916: *
917: * `dh' must be locked on entry and remains so on return.
918: */
919: int
920: ufsdirhash_findslot(struct dirhash *dh, char *name, int namelen, doff_t offset)
921: {
922: int slot;
923:
924: mtx_assert(&dh->dh_mtx, MA_OWNED);
925:
926: /* Find the entry. */
927: DIRHASH_ASSERT(dh->dh_hused < dh->dh_hlen, ("dirhash find full"));
928: slot = ufsdirhash_hash(dh, name, namelen);
929: while (DH_ENTRY(dh, slot) != offset &&
930: DH_ENTRY(dh, slot) != DIRHASH_EMPTY)
931: slot = WRAPINCR(slot, dh->dh_hlen);
932: if (DH_ENTRY(dh, slot) != offset)
933: panic("ufsdirhash_findslot: '%.*s' not found", namelen, name);
934:
935: return (slot);
936: }
937:
938: /*
939: * Remove the entry corresponding to the specified slot from the hash array.
940: *
941: * `dh' must be locked on entry and remains so on return.
942: */
943: void
944: ufsdirhash_delslot(struct dirhash *dh, int slot)
945: {
946: int i;
947:
948: mtx_assert(&dh->dh_mtx, MA_OWNED);
949:
950: /* Mark the entry as deleted. */
951: DH_ENTRY(dh, slot) = DIRHASH_DEL;
952:
953: /* If this is the end of a chain of DIRHASH_DEL slots, remove them. */
954: for (i = slot; DH_ENTRY(dh, i) == DIRHASH_DEL; )
955: i = WRAPINCR(i, dh->dh_hlen);
956: if (DH_ENTRY(dh, i) == DIRHASH_EMPTY) {
957: i = WRAPDECR(i, dh->dh_hlen);
958: while (DH_ENTRY(dh, i) == DIRHASH_DEL) {
959: DH_ENTRY(dh, i) = DIRHASH_EMPTY;
960: dh->dh_hused--;
961: i = WRAPDECR(i, dh->dh_hlen);
962: }
963: DIRHASH_ASSERT(dh->dh_hused >= 0, ("ufsdirhash_delslot neg hlen"));
964: }
965: }
966:
967: /*
968: * Given a directory entry and its offset, find the offset of the
969: * previous entry in the same DIRBLKSIZ-sized block. Returns an
970: * offset, or -1 if there is no previous entry in the block or some
971: * other problem occurred.
972: */
973: doff_t
974: ufsdirhash_getprev(struct direct *dirp, doff_t offset)
975: {
976: struct direct *dp;
977: char *blkbuf;
978: doff_t blkoff, prevoff;
979: int entrypos, i;
980:
981: blkoff = offset & ~(DIRBLKSIZ - 1); /* offset of start of block */
982: entrypos = offset & (DIRBLKSIZ - 1); /* entry relative to block */
983: blkbuf = (char *)dirp - entrypos;
984: prevoff = blkoff;
985:
986: /* If `offset' is the start of a block, there is no previous entry. */
987: if (entrypos == 0)
988: return (-1);
989:
990: /* Scan from the start of the block until we get to the entry. */
991: for (i = 0; i < entrypos; i += dp->d_reclen) {
992: dp = (struct direct *)(blkbuf + i);
993: if (dp->d_reclen == 0 || i + dp->d_reclen > entrypos)
994: return (-1); /* Corrupted directory. */
995: prevoff = blkoff + i;
996: }
997: return (prevoff);
998: }
999:
1000: /*
1001: * Try to free up `wanted' bytes by stealing memory from existing
1002: * dirhashes. Returns zero with list locked if successful.
1003: */
1004: int
1005: ufsdirhash_recycle(int wanted)
1006: {
1007: struct dirhash *dh;
1008: doff_t **hash;
1009: u_int8_t *blkfree;
1010: int i, mem, narrays;
1011:
1012: DIRHASHLIST_LOCK();
1013: while (wanted + ufs_dirhashmem > ufs_dirhashmaxmem) {
1014: /* Find a dirhash, and lock it. */
1015: if ((dh = TAILQ_FIRST(&ufsdirhash_list)) == NULL) {
1016: DIRHASHLIST_UNLOCK();
1017: return (-1);
1018: }
1019: DIRHASH_LOCK(dh);
1020: DIRHASH_ASSERT(dh->dh_hash != NULL, ("dirhash: NULL hash on list"));
1021:
1022: /* Decrement the score; only recycle if it becomes zero. */
1023: if (--dh->dh_score > 0) {
1024: DIRHASH_UNLOCK(dh);
1025: DIRHASHLIST_UNLOCK();
1026: return (-1);
1027: }
1028:
1029: /* Remove it from the list and detach its memory. */
1030: TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list);
1031: dh->dh_onlist = 0;
1032: hash = dh->dh_hash;
1033: dh->dh_hash = NULL;
1034: blkfree = dh->dh_blkfree;
1035: dh->dh_blkfree = NULL;
1036: narrays = dh->dh_narrays;
1037: mem = narrays * sizeof(*dh->dh_hash) +
1038: narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) +
1039: dh->dh_nblk * sizeof(*dh->dh_blkfree);
1040:
1041: /* Unlock everything, free the detached memory. */
1042: DIRHASH_UNLOCK(dh);
1043: DIRHASHLIST_UNLOCK();
1044: for (i = 0; i < narrays; i++)
1045: DIRHASH_BLKFREE(hash[i]);
1046: free(hash, M_DIRHASH);
1047: free(blkfree, M_DIRHASH);
1048:
1049: /* Account for the returned memory, and repeat if necessary. */
1050: DIRHASHLIST_LOCK();
1051: ufs_dirhashmem -= mem;
1052: }
1053: /* Success; return with list locked. */
1054: return (0);
1055: }
1056:
1057:
1058: void
1059: ufsdirhash_init()
1060: {
1061: pool_init(&ufsdirhash_pool, DH_NBLKOFF * sizeof(doff_t), 0, 0, 0,
1062: "dirhash", &pool_allocator_nointr);
1063: pool_sethiwat(&ufsdirhash_pool, 512);
1064: TAILQ_INIT(&ufsdirhash_list);
1065: #if defined (__sparc__) && !defined (__sparc64__)
1066: if (!CPU_ISSUN4OR4C)
1067: #elif defined (__vax__)
1068: if (0)
1069: #endif
1070: ufs_dirhashmaxmem = 2 * 1024 * 1024;
1071: ufs_mindirhashsize = 5 * DIRBLKSIZ;
1072: }
1073:
1074: void
1075: ufsdirhash_uninit()
1076: {
1077: DIRHASH_ASSERT(TAILQ_EMPTY(&ufsdirhash_list), ("ufsdirhash_uninit"));
1078: pool_destroy(&ufsdirhash_pool);
1079: }
CVSweb
![[BACK]](/icons/back.gif){kind=icon}
Return to ufs_dirhash.c CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [local] / sys / ufs / ufs