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Annotation of src/sys/ufs/ufs/ufs_dirhash.c, Revision 1.21.10.1

1.21.10.1! yamt        1: /*     $NetBSD: ufs_dirhash.c,v 1.21 2008/01/03 19:28:50 ad Exp $      */
1.1       rumble      2:
                      3: /*
                      4:  * Copyright (c) 2001, 2002 Ian Dowse.  All rights reserved.
                      5:  *
                      6:  * Redistribution and use in source and binary forms, with or without
                      7:  * modification, are permitted provided that the following conditions
                      8:  * are met:
                      9:  * 1. Redistributions of source code must retain the above copyright
                     10:  *    notice, this list of conditions and the following disclaimer.
                     11:  * 2. Redistributions in binary form must reproduce the above copyright
                     12:  *    notice, this list of conditions and the following disclaimer in the
                     13:  *    documentation and/or other materials provided with the distribution.
                     14:  *
                     15:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
                     16:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     17:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     18:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
                     19:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     20:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     21:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     22:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     23:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     24:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     25:  * SUCH DAMAGE.
                     26:  *
                     27:  * $FreeBSD: src/sys/ufs/ufs/ufs_dirhash.c,v 1.3.2.8 2004/12/08 11:54:13 dwmalone Exp $
                     28:  */
                     29:
1.19      rumble     30: #include <sys/cdefs.h>
1.21.10.1! yamt       31: __KERNEL_RCSID(0, "$NetBSD: ufs_dirhash.c,v 1.21 2008/01/03 19:28:50 ad Exp $");
1.19      rumble     32:
1.1       rumble     33: /*
                     34:  * This implements a hash-based lookup scheme for UFS directories.
                     35:  */
                     36:
                     37: #include <sys/param.h>
                     38: #include <sys/systm.h>
                     39: #include <sys/kernel.h>
1.21.10.1! yamt       40: #include <sys/kmem.h>
1.1       rumble     41: #include <sys/types.h>
                     42: #include <sys/hash.h>
                     43: #include <sys/proc.h>
                     44: #include <sys/buf.h>
                     45: #include <sys/vnode.h>
                     46: #include <sys/mount.h>
                     47: #include <sys/pool.h>
                     48: #include <sys/sysctl.h>
1.21.10.1! yamt       49: #include <sys/atomic.h>
1.1       rumble     50:
                     51: #include <ufs/ufs/inode.h>
                     52: #include <ufs/ufs/dir.h>
                     53: #include <ufs/ufs/dirhash.h>
                     54: #include <ufs/ufs/ufsmount.h>
                     55: #include <ufs/ufs/ufs_bswap.h>
                     56: #include <ufs/ufs/ufs_extern.h>
                     57:
                     58: #define WRAPINCR(val, limit)   (((val) + 1 == (limit)) ? 0 : ((val) + 1))
                     59: #define WRAPDECR(val, limit)   (((val) == 0) ? ((limit) - 1) : ((val) - 1))
                     60: #define OFSFMT(ip)             ((ip)->i_ump->um_maxsymlinklen <= 0)
                     61: #define BLKFREE2IDX(n)         ((n) > DH_NFSTATS ? DH_NFSTATS : (n))
                     62:
1.21.10.1! yamt       63: static u_int ufs_dirhashminblks = 5;
        !            64: static u_int ufs_dirhashmaxmem = 2 * 1024 * 1024;
        !            65: static u_int ufs_dirhashmem;
        !            66: static u_int ufs_dirhashcheck = 0;
1.1       rumble     67:
                     68: static int ufsdirhash_hash(struct dirhash *dh, const char *name, int namelen);
                     69: static void ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff,
                     70:           int dirblksiz);
                     71: static void ufsdirhash_delslot(struct dirhash *dh, int slot);
                     72: static int ufsdirhash_findslot(struct dirhash *dh, const char *name,
                     73:           int namelen, doff_t offset);
                     74: static doff_t ufsdirhash_getprev(struct direct *dp, doff_t offset,
                     75:           int dirblksiz);
                     76: static int ufsdirhash_recycle(int wanted);
                     77:
1.21.10.1! yamt       78: static pool_cache_t ufsdirhashblk_cache;
1.21      ad         79: static pool_cache_t ufsdirhash_cache;
1.1       rumble     80:
1.16      ad         81: #define DIRHASHLIST_LOCK()             mutex_enter(&ufsdirhash_lock)
                     82: #define DIRHASHLIST_UNLOCK()           mutex_exit(&ufsdirhash_lock)
                     83: #define DIRHASH_LOCK(dh)               mutex_enter(&(dh)->dh_lock)
                     84: #define DIRHASH_UNLOCK(dh)             mutex_exit(&(dh)->dh_lock)
1.21.10.1! yamt       85: #define DIRHASH_BLKALLOC()             \
        !            86:     pool_cache_get(ufsdirhashblk_cache, PR_NOWAIT)
1.21      ad         87: #define DIRHASH_BLKFREE(ptr)           \
1.21.10.1! yamt       88:     pool_cache_put(ufsdirhashblk_cache, ptr)
1.1       rumble     89:
                     90: /* Dirhash list; recently-used entries are near the tail. */
                     91: static TAILQ_HEAD(, dirhash) ufsdirhash_list;
                     92:
1.16      ad         93: /* Protects: ufsdirhash_list, `dh_list' field, ufs_dirhashmem. */
                     94: static kmutex_t ufsdirhash_lock;
                     95:
1.21.10.1! yamt       96: static struct sysctllog *ufsdirhash_sysctl_log;
        !            97:
1.16      ad         98: /*
                     99:  * Locking order:
                    100:  *     ufsdirhash_lock
                    101:  *     dh_lock
                    102:  *
                    103:  * The dh_lock mutex should be acquired either via the inode lock, or via
                    104:  * ufsdirhash_lock. Only the owner of the inode may free the associated
                    105:  * dirhash, but anything can steal its memory and set dh_hash to NULL.
                    106:  */
                    107:
1.1       rumble    108: /*
                    109:  * Attempt to build up a hash table for the directory contents in
                    110:  * inode 'ip'. Returns 0 on success, or -1 of the operation failed.
                    111:  */
                    112: int
                    113: ufsdirhash_build(struct inode *ip)
                    114: {
                    115:        struct dirhash *dh;
                    116:        struct buf *bp = NULL;
                    117:        struct direct *ep;
                    118:        struct vnode *vp;
                    119:        doff_t bmask, pos;
                    120:        int dirblocks, i, j, memreqd, nblocks, narrays, nslots, slot;
1.2       perry     121:        const int needswap = UFS_MPNEEDSWAP(ip->i_ump);
1.1       rumble    122:        int dirblksiz = ip->i_ump->um_dirblksiz;
                    123:
                    124:        /* Check if we can/should use dirhash. */
                    125:        if (ip->i_dirhash == NULL) {
                    126:                if (ip->i_size < (ufs_dirhashminblks * dirblksiz) || OFSFMT(ip))
                    127:                        return (-1);
                    128:        } else {
                    129:                /* Hash exists, but sysctls could have changed. */
                    130:                if (ip->i_size < (ufs_dirhashminblks * dirblksiz) ||
                    131:                    ufs_dirhashmem > ufs_dirhashmaxmem) {
                    132:                        ufsdirhash_free(ip);
                    133:                        return (-1);
                    134:                }
                    135:                /* Check if hash exists and is intact (note: unlocked read). */
                    136:                if (ip->i_dirhash->dh_hash != NULL)
                    137:                        return (0);
                    138:                /* Free the old, recycled hash and build a new one. */
                    139:                ufsdirhash_free(ip);
                    140:        }
                    141:
                    142:        /* Don't hash removed directories. */
1.21.10.1! yamt      143:        if (ip->i_nlink == 0)
1.1       rumble    144:                return (-1);
                    145:
                    146:        vp = ip->i_vnode;
                    147:        /* Allocate 50% more entries than this dir size could ever need. */
                    148:        KASSERT(ip->i_size >= dirblksiz);
                    149:        nslots = ip->i_size / DIRECTSIZ(1);
                    150:        nslots = (nslots * 3 + 1) / 2;
                    151:        narrays = howmany(nslots, DH_NBLKOFF);
                    152:        nslots = narrays * DH_NBLKOFF;
                    153:        dirblocks = howmany(ip->i_size, dirblksiz);
                    154:        nblocks = (dirblocks * 3 + 1) / 2;
                    155:
                    156:        memreqd = sizeof(*dh) + narrays * sizeof(*dh->dh_hash) +
                    157:            narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) +
                    158:            nblocks * sizeof(*dh->dh_blkfree);
1.21.10.1! yamt      159:
        !           160:        while (atomic_add_int_nv(&ufs_dirhashmem, memreqd) >
        !           161:            ufs_dirhashmaxmem) {
        !           162:                atomic_add_int(&ufs_dirhashmem, -memreqd);
1.1       rumble    163:                if (memreqd > ufs_dirhashmaxmem / 2)
                    164:                        return (-1);
                    165:                /* Try to free some space. */
                    166:                if (ufsdirhash_recycle(memreqd) != 0)
                    167:                        return (-1);
1.21.10.1! yamt      168:                else
        !           169:                        DIRHASHLIST_UNLOCK();
1.1       rumble    170:        }
                    171:
                    172:        /*
                    173:         * Use non-blocking mallocs so that we will revert to a linear
                    174:         * lookup on failure rather than potentially blocking forever.
                    175:         */
1.21.10.1! yamt      176:        dh = pool_cache_get(ufsdirhash_cache, PR_NOWAIT);
1.1       rumble    177:        if (dh == NULL) {
1.21.10.1! yamt      178:                atomic_add_int(&ufs_dirhashmem, -memreqd);
1.1       rumble    179:                return (-1);
                    180:        }
1.21.10.1! yamt      181:        memset(dh, 0, sizeof(*dh));
1.16      ad        182:        mutex_init(&dh->dh_lock, MUTEX_DEFAULT, IPL_NONE);
1.21.10.1! yamt      183:        DIRHASH_LOCK(dh);
        !           184:        dh->dh_hashsz = narrays * sizeof(dh->dh_hash[0]);
        !           185:        dh->dh_hash = kmem_zalloc(dh->dh_hashsz, KM_NOSLEEP);
        !           186:        dh->dh_blkfreesz = nblocks * sizeof(dh->dh_blkfree[0]);
        !           187:        dh->dh_blkfree = kmem_zalloc(dh->dh_blkfreesz, KM_NOSLEEP);
1.1       rumble    188:        if (dh->dh_hash == NULL || dh->dh_blkfree == NULL)
                    189:                goto fail;
                    190:        for (i = 0; i < narrays; i++) {
1.21.10.1! yamt      191:                if ((dh->dh_hash[i] = DIRHASH_BLKALLOC()) == NULL)
1.1       rumble    192:                        goto fail;
                    193:                for (j = 0; j < DH_NBLKOFF; j++)
                    194:                        dh->dh_hash[i][j] = DIRHASH_EMPTY;
                    195:        }
                    196:
                    197:        /* Initialise the hash table and block statistics. */
                    198:        dh->dh_narrays = narrays;
                    199:        dh->dh_hlen = nslots;
                    200:        dh->dh_nblk = nblocks;
                    201:        dh->dh_dirblks = dirblocks;
                    202:        for (i = 0; i < dirblocks; i++)
                    203:                dh->dh_blkfree[i] = dirblksiz / DIRALIGN;
                    204:        for (i = 0; i < DH_NFSTATS; i++)
                    205:                dh->dh_firstfree[i] = -1;
                    206:        dh->dh_firstfree[DH_NFSTATS] = 0;
                    207:        dh->dh_seqopt = 0;
                    208:        dh->dh_seqoff = 0;
                    209:        dh->dh_score = DH_SCOREINIT;
                    210:        ip->i_dirhash = dh;
                    211:
                    212:        bmask = VFSTOUFS(vp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
                    213:        pos = 0;
                    214:        while (pos < ip->i_size) {
1.8       yamt      215:                if ((curcpu()->ci_schedstate.spc_flags & SPCF_SHOULDYIELD)
                    216:                    != 0) {
1.12      ad        217:                        preempt();
1.8       yamt      218:                }
1.1       rumble    219:                /* If necessary, get the next directory block. */
                    220:                if ((pos & bmask) == 0) {
                    221:                        if (bp != NULL)
1.20      ad        222:                                brelse(bp, 0);
1.21.10.1! yamt      223:                        if (ufs_blkatoff(vp, (off_t)pos, NULL, &bp, false) != 0)
1.1       rumble    224:                                goto fail;
                    225:                }
                    226:
                    227:                /* Add this entry to the hash. */
                    228:                ep = (struct direct *)((char *)bp->b_data + (pos & bmask));
                    229:                if (ep->d_reclen == 0 || ep->d_reclen >
                    230:                    dirblksiz - (pos & (dirblksiz - 1))) {
                    231:                        /* Corrupted directory. */
1.20      ad        232:                        brelse(bp, 0);
1.1       rumble    233:                        goto fail;
                    234:                }
                    235:                if (ep->d_ino != 0) {
                    236:                        /* Add the entry (simplified ufsdirhash_add). */
                    237:                        slot = ufsdirhash_hash(dh, ep->d_name, ep->d_namlen);
                    238:                        while (DH_ENTRY(dh, slot) != DIRHASH_EMPTY)
                    239:                                slot = WRAPINCR(slot, dh->dh_hlen);
                    240:                        dh->dh_hused++;
                    241:                        DH_ENTRY(dh, slot) = pos;
                    242:                        ufsdirhash_adjfree(dh, pos, -DIRSIZ(0, ep, needswap),
                    243:                            dirblksiz);
                    244:                }
                    245:                pos += ep->d_reclen;
                    246:        }
                    247:
                    248:        if (bp != NULL)
1.20      ad        249:                brelse(bp, 0);
1.1       rumble    250:        DIRHASHLIST_LOCK();
                    251:        TAILQ_INSERT_TAIL(&ufsdirhash_list, dh, dh_list);
                    252:        dh->dh_onlist = 1;
1.21.10.1! yamt      253:        DIRHASH_UNLOCK(dh);
1.1       rumble    254:        DIRHASHLIST_UNLOCK();
                    255:        return (0);
                    256:
                    257: fail:
1.21.10.1! yamt      258:        DIRHASH_UNLOCK(dh);
1.1       rumble    259:        if (dh->dh_hash != NULL) {
                    260:                for (i = 0; i < narrays; i++)
                    261:                        if (dh->dh_hash[i] != NULL)
                    262:                                DIRHASH_BLKFREE(dh->dh_hash[i]);
1.21.10.1! yamt      263:                kmem_free(dh->dh_hash, dh->dh_hashsz);
1.1       rumble    264:        }
                    265:        if (dh->dh_blkfree != NULL)
1.21.10.1! yamt      266:                kmem_free(dh->dh_blkfree, dh->dh_blkfreesz);
1.16      ad        267:        mutex_destroy(&dh->dh_lock);
1.21.10.1! yamt      268:        pool_cache_put(ufsdirhash_cache, dh);
1.1       rumble    269:        ip->i_dirhash = NULL;
1.21.10.1! yamt      270:        atomic_add_int(&ufs_dirhashmem, -memreqd);
1.1       rumble    271:        return (-1);
                    272: }
                    273:
                    274: /*
                    275:  * Free any hash table associated with inode 'ip'.
                    276:  */
                    277: void
                    278: ufsdirhash_free(struct inode *ip)
                    279: {
                    280:        struct dirhash *dh;
                    281:        int i, mem;
                    282:
                    283:        if ((dh = ip->i_dirhash) == NULL)
                    284:                return;
                    285:
1.21.10.1! yamt      286:        if (dh->dh_onlist) {
        !           287:                DIRHASHLIST_LOCK();
        !           288:                if (dh->dh_onlist)
        !           289:                        TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list);
        !           290:                DIRHASHLIST_UNLOCK();
        !           291:        }
1.1       rumble    292:
1.21.10.1! yamt      293:        /* The dirhash pointed to by 'dh' is exclusively ours now. */
1.1       rumble    294:        mem = sizeof(*dh);
                    295:        if (dh->dh_hash != NULL) {
                    296:                for (i = 0; i < dh->dh_narrays; i++)
                    297:                        DIRHASH_BLKFREE(dh->dh_hash[i]);
1.21.10.1! yamt      298:                kmem_free(dh->dh_hash, dh->dh_hashsz);
        !           299:                kmem_free(dh->dh_blkfree, dh->dh_blkfreesz);
        !           300:                mem += dh->dh_hashsz;
        !           301:                mem += dh->dh_narrays * DH_NBLKOFF * sizeof(**dh->dh_hash);
        !           302:                mem += dh->dh_nblk * sizeof(*dh->dh_blkfree);
1.1       rumble    303:        }
1.16      ad        304:        mutex_destroy(&dh->dh_lock);
1.21.10.1! yamt      305:        pool_cache_put(ufsdirhash_cache, dh);
1.1       rumble    306:        ip->i_dirhash = NULL;
                    307:
1.21.10.1! yamt      308:        atomic_add_int(&ufs_dirhashmem, -mem);
1.1       rumble    309: }
                    310:
                    311: /*
                    312:  * Find the offset of the specified name within the given inode.
                    313:  * Returns 0 on success, ENOENT if the entry does not exist, or
                    314:  * EJUSTRETURN if the caller should revert to a linear search.
                    315:  *
                    316:  * If successful, the directory offset is stored in *offp, and a
                    317:  * pointer to a struct buf containing the entry is stored in *bpp. If
                    318:  * prevoffp is non-NULL, the offset of the previous entry within
                    319:  * the DIRBLKSIZ-sized block is stored in *prevoffp (if the entry
                    320:  * is the first in a block, the start of the block is used).
                    321:  */
                    322: int
                    323: ufsdirhash_lookup(struct inode *ip, const char *name, int namelen, doff_t *offp,
                    324:     struct buf **bpp, doff_t *prevoffp)
                    325: {
                    326:        struct dirhash *dh, *dh_next;
                    327:        struct direct *dp;
                    328:        struct vnode *vp;
                    329:        struct buf *bp;
                    330:        doff_t blkoff, bmask, offset, prevoff;
                    331:        int i, slot;
1.2       perry     332:        const int needswap = UFS_MPNEEDSWAP(ip->i_ump);
1.1       rumble    333:        int dirblksiz = ip->i_ump->um_dirblksiz;
                    334:
                    335:        if ((dh = ip->i_dirhash) == NULL)
                    336:                return (EJUSTRETURN);
1.21.10.1! yamt      337:
1.1       rumble    338:        /*
                    339:         * Move this dirhash towards the end of the list if it has a
1.16      ad        340:         * score higher than the next entry, and acquire the dh_lock.
1.1       rumble    341:         * Optimise the case where it's already the last by performing
                    342:         * an unlocked read of the TAILQ_NEXT pointer.
                    343:         *
1.16      ad        344:         * In both cases, end up holding just dh_lock.
1.1       rumble    345:         */
                    346:        if (TAILQ_NEXT(dh, dh_list) != NULL) {
                    347:                DIRHASHLIST_LOCK();
                    348:                DIRHASH_LOCK(dh);
                    349:                /*
                    350:                 * If the new score will be greater than that of the next
                    351:                 * entry, then move this entry past it. With both mutexes
                    352:                 * held, dh_next won't go away, but its dh_score could
                    353:                 * change; that's not important since it is just a hint.
                    354:                 */
                    355:                if (dh->dh_hash != NULL &&
                    356:                    (dh_next = TAILQ_NEXT(dh, dh_list)) != NULL &&
                    357:                    dh->dh_score >= dh_next->dh_score) {
                    358:                        KASSERT(dh->dh_onlist);
                    359:                        TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list);
                    360:                        TAILQ_INSERT_AFTER(&ufsdirhash_list, dh_next, dh,
                    361:                            dh_list);
                    362:                }
                    363:                DIRHASHLIST_UNLOCK();
                    364:        } else {
                    365:                /* Already the last, though that could change as we wait. */
                    366:                DIRHASH_LOCK(dh);
                    367:        }
                    368:        if (dh->dh_hash == NULL) {
                    369:                DIRHASH_UNLOCK(dh);
                    370:                ufsdirhash_free(ip);
                    371:                return (EJUSTRETURN);
                    372:        }
                    373:
                    374:        /* Update the score. */
                    375:        if (dh->dh_score < DH_SCOREMAX)
                    376:                dh->dh_score++;
                    377:
                    378:        vp = ip->i_vnode;
                    379:        bmask = VFSTOUFS(vp->v_mount)->um_mountp->mnt_stat.f_iosize - 1;
                    380:        blkoff = -1;
                    381:        bp = NULL;
                    382: restart:
                    383:        slot = ufsdirhash_hash(dh, name, namelen);
                    384:
                    385:        if (dh->dh_seqopt) {
                    386:                /*
                    387:                 * Sequential access optimisation. dh_seqoff contains the
                    388:                 * offset of the directory entry immediately following
                    389:                 * the last entry that was looked up. Check if this offset
                    390:                 * appears in the hash chain for the name we are looking for.
                    391:                 */
                    392:                for (i = slot; (offset = DH_ENTRY(dh, i)) != DIRHASH_EMPTY;
                    393:                    i = WRAPINCR(i, dh->dh_hlen))
                    394:                        if (offset == dh->dh_seqoff)
                    395:                                break;
                    396:                if (offset == dh->dh_seqoff) {
                    397:                        /*
                    398:                         * We found an entry with the expected offset. This
                    399:                         * is probably the entry we want, but if not, the
                    400:                         * code below will turn off seqoff and retry.
1.2       perry     401:                         */
1.1       rumble    402:                        slot = i;
1.2       perry     403:                } else
1.1       rumble    404:                        dh->dh_seqopt = 0;
                    405:        }
                    406:
                    407:        for (; (offset = DH_ENTRY(dh, slot)) != DIRHASH_EMPTY;
                    408:            slot = WRAPINCR(slot, dh->dh_hlen)) {
                    409:                if (offset == DIRHASH_DEL)
                    410:                        continue;
                    411:
                    412:                if (offset < 0 || offset >= ip->i_size)
                    413:                        panic("ufsdirhash_lookup: bad offset in hash array");
                    414:                if ((offset & ~bmask) != blkoff) {
                    415:                        if (bp != NULL)
1.20      ad        416:                                brelse(bp, 0);
1.1       rumble    417:                        blkoff = offset & ~bmask;
1.21.10.1! yamt      418:                        if (ufs_blkatoff(vp, (off_t)blkoff,
        !           419:                            NULL, &bp, true) != 0) {
        !           420:                                DIRHASH_UNLOCK(dh);
1.1       rumble    421:                                return (EJUSTRETURN);
1.21.10.1! yamt      422:                        }
1.1       rumble    423:                }
1.13      christos  424:                dp = (struct direct *)((char *)bp->b_data + (offset & bmask));
1.1       rumble    425:                if (dp->d_reclen == 0 || dp->d_reclen >
                    426:                    dirblksiz - (offset & (dirblksiz - 1))) {
                    427:                        /* Corrupted directory. */
1.21.10.1! yamt      428:                        DIRHASH_UNLOCK(dh);
1.20      ad        429:                        brelse(bp, 0);
1.1       rumble    430:                        return (EJUSTRETURN);
                    431:                }
                    432:                if (dp->d_namlen == namelen &&
1.21.10.1! yamt      433:                    memcmp(dp->d_name, name, namelen) == 0) {
1.1       rumble    434:                        /* Found. Get the prev offset if needed. */
                    435:                        if (prevoffp != NULL) {
                    436:                                if (offset & (dirblksiz - 1)) {
                    437:                                        prevoff = ufsdirhash_getprev(dp,
                    438:                                            offset, dirblksiz);
                    439:                                        if (prevoff == -1) {
1.20      ad        440:                                                brelse(bp, 0);
1.1       rumble    441:                                                return (EJUSTRETURN);
                    442:                                        }
                    443:                                } else
                    444:                                        prevoff = offset;
                    445:                                *prevoffp = prevoff;
                    446:                        }
                    447:
                    448:                        /* Check for sequential access, and update offset. */
                    449:                        if (dh->dh_seqopt == 0 && dh->dh_seqoff == offset)
                    450:                                dh->dh_seqopt = 1;
                    451:                        dh->dh_seqoff = offset + DIRSIZ(0, dp, needswap);
1.21.10.1! yamt      452:                        DIRHASH_UNLOCK(dh);
1.1       rumble    453:
                    454:                        *bpp = bp;
                    455:                        *offp = offset;
                    456:                        return (0);
                    457:                }
                    458:
                    459:                if (dh->dh_hash == NULL) {
                    460:                        DIRHASH_UNLOCK(dh);
                    461:                        if (bp != NULL)
1.20      ad        462:                                brelse(bp, 0);
1.1       rumble    463:                        ufsdirhash_free(ip);
                    464:                        return (EJUSTRETURN);
                    465:                }
                    466:                /*
                    467:                 * When the name doesn't match in the seqopt case, go back
                    468:                 * and search normally.
                    469:                 */
                    470:                if (dh->dh_seqopt) {
                    471:                        dh->dh_seqopt = 0;
                    472:                        goto restart;
                    473:                }
                    474:        }
                    475:        DIRHASH_UNLOCK(dh);
                    476:        if (bp != NULL)
1.20      ad        477:                brelse(bp, 0);
1.1       rumble    478:        return (ENOENT);
                    479: }
                    480:
                    481: /*
                    482:  * Find a directory block with room for 'slotneeded' bytes. Returns
                    483:  * the offset of the directory entry that begins the free space.
                    484:  * This will either be the offset of an existing entry that has free
                    485:  * space at the end, or the offset of an entry with d_ino == 0 at
                    486:  * the start of a DIRBLKSIZ block.
                    487:  *
                    488:  * To use the space, the caller may need to compact existing entries in
                    489:  * the directory. The total number of bytes in all of the entries involved
                    490:  * in the compaction is stored in *slotsize. In other words, all of
                    491:  * the entries that must be compacted are exactly contained in the
                    492:  * region beginning at the returned offset and spanning *slotsize bytes.
                    493:  *
                    494:  * Returns -1 if no space was found, indicating that the directory
                    495:  * must be extended.
                    496:  */
                    497: doff_t
                    498: ufsdirhash_findfree(struct inode *ip, int slotneeded, int *slotsize)
                    499: {
                    500:        struct direct *dp;
                    501:        struct dirhash *dh;
                    502:        struct buf *bp;
                    503:        doff_t pos, slotstart;
                    504:        int dirblock, error, freebytes, i;
1.2       perry     505:        const int needswap = UFS_MPNEEDSWAP(ip->i_ump);
1.1       rumble    506:        int dirblksiz = ip->i_ump->um_dirblksiz;
                    507:
                    508:        if ((dh = ip->i_dirhash) == NULL)
                    509:                return (-1);
1.21.10.1! yamt      510:
1.1       rumble    511:        DIRHASH_LOCK(dh);
                    512:        if (dh->dh_hash == NULL) {
                    513:                DIRHASH_UNLOCK(dh);
                    514:                ufsdirhash_free(ip);
                    515:                return (-1);
                    516:        }
                    517:
                    518:        /* Find a directory block with the desired free space. */
                    519:        dirblock = -1;
                    520:        for (i = howmany(slotneeded, DIRALIGN); i <= DH_NFSTATS; i++)
                    521:                if ((dirblock = dh->dh_firstfree[i]) != -1)
                    522:                        break;
                    523:        if (dirblock == -1) {
                    524:                DIRHASH_UNLOCK(dh);
                    525:                return (-1);
                    526:        }
                    527:
                    528:        KASSERT(dirblock < dh->dh_nblk &&
                    529:            dh->dh_blkfree[dirblock] >= howmany(slotneeded, DIRALIGN));
                    530:        pos = dirblock * dirblksiz;
1.21.10.1! yamt      531:        error = ufs_blkatoff(ip->i_vnode, (off_t)pos, (void *)&dp, &bp, false);
        !           532:        if (error) {
        !           533:                DIRHASH_UNLOCK(dh);
1.1       rumble    534:                return (-1);
1.21.10.1! yamt      535:        }
1.1       rumble    536:        /* Find the first entry with free space. */
                    537:        for (i = 0; i < dirblksiz; ) {
                    538:                if (dp->d_reclen == 0) {
1.21.10.1! yamt      539:                        DIRHASH_UNLOCK(dh);
1.20      ad        540:                        brelse(bp, 0);
1.1       rumble    541:                        return (-1);
                    542:                }
                    543:                if (dp->d_ino == 0 || dp->d_reclen > DIRSIZ(0, dp, needswap))
                    544:                        break;
                    545:                i += dp->d_reclen;
                    546:                dp = (struct direct *)((char *)dp + dp->d_reclen);
                    547:        }
                    548:        if (i > dirblksiz) {
1.21.10.1! yamt      549:                DIRHASH_UNLOCK(dh);
1.20      ad        550:                brelse(bp, 0);
1.1       rumble    551:                return (-1);
                    552:        }
                    553:        slotstart = pos + i;
                    554:
                    555:        /* Find the range of entries needed to get enough space */
                    556:        freebytes = 0;
                    557:        while (i < dirblksiz && freebytes < slotneeded) {
                    558:                freebytes += dp->d_reclen;
                    559:                if (dp->d_ino != 0)
                    560:                        freebytes -= DIRSIZ(0, dp, needswap);
                    561:                if (dp->d_reclen == 0) {
1.21.10.1! yamt      562:                        DIRHASH_UNLOCK(dh);
1.20      ad        563:                        brelse(bp, 0);
1.1       rumble    564:                        return (-1);
                    565:                }
                    566:                i += dp->d_reclen;
                    567:                dp = (struct direct *)((char *)dp + dp->d_reclen);
                    568:        }
                    569:        if (i > dirblksiz) {
1.21.10.1! yamt      570:                DIRHASH_UNLOCK(dh);
1.20      ad        571:                brelse(bp, 0);
1.1       rumble    572:                return (-1);
                    573:        }
                    574:        if (freebytes < slotneeded)
                    575:                panic("ufsdirhash_findfree: free mismatch");
1.21.10.1! yamt      576:        DIRHASH_UNLOCK(dh);
1.20      ad        577:        brelse(bp, 0);
1.1       rumble    578:        *slotsize = pos + i - slotstart;
                    579:        return (slotstart);
                    580: }
                    581:
                    582: /*
                    583:  * Return the start of the unused space at the end of a directory, or
                    584:  * -1 if there are no trailing unused blocks.
                    585:  */
                    586: doff_t
                    587: ufsdirhash_enduseful(struct inode *ip)
                    588: {
                    589:        struct dirhash *dh;
                    590:        int i;
                    591:        int dirblksiz = ip->i_ump->um_dirblksiz;
                    592:
                    593:        if ((dh = ip->i_dirhash) == NULL)
                    594:                return (-1);
1.21.10.1! yamt      595:
1.1       rumble    596:        DIRHASH_LOCK(dh);
                    597:        if (dh->dh_hash == NULL) {
                    598:                DIRHASH_UNLOCK(dh);
                    599:                ufsdirhash_free(ip);
                    600:                return (-1);
                    601:        }
                    602:
                    603:        if (dh->dh_blkfree[dh->dh_dirblks - 1] != dirblksiz / DIRALIGN) {
                    604:                DIRHASH_UNLOCK(dh);
                    605:                return (-1);
                    606:        }
                    607:
                    608:        for (i = dh->dh_dirblks - 1; i >= 0; i--)
                    609:                if (dh->dh_blkfree[i] != dirblksiz / DIRALIGN)
                    610:                        break;
                    611:        DIRHASH_UNLOCK(dh);
                    612:        return ((doff_t)(i + 1) * dirblksiz);
                    613: }
                    614:
                    615: /*
                    616:  * Insert information into the hash about a new directory entry. dirp
                    617:  * points to a struct direct containing the entry, and offset specifies
                    618:  * the offset of this entry.
                    619:  */
                    620: void
                    621: ufsdirhash_add(struct inode *ip, struct direct *dirp, doff_t offset)
                    622: {
                    623:        struct dirhash *dh;
                    624:        int slot;
                    625:        const int needswap = UFS_MPNEEDSWAP(ip->i_ump);
                    626:        int dirblksiz = ip->i_ump->um_dirblksiz;
                    627:
                    628:        if ((dh = ip->i_dirhash) == NULL)
                    629:                return;
1.21.10.1! yamt      630:
1.1       rumble    631:        DIRHASH_LOCK(dh);
                    632:        if (dh->dh_hash == NULL) {
                    633:                DIRHASH_UNLOCK(dh);
                    634:                ufsdirhash_free(ip);
                    635:                return;
                    636:        }
                    637:
                    638:        KASSERT(offset < dh->dh_dirblks * dirblksiz);
                    639:        /*
                    640:         * Normal hash usage is < 66%. If the usage gets too high then
                    641:         * remove the hash entirely and let it be rebuilt later.
                    642:         */
                    643:        if (dh->dh_hused >= (dh->dh_hlen * 3) / 4) {
                    644:                DIRHASH_UNLOCK(dh);
                    645:                ufsdirhash_free(ip);
                    646:                return;
                    647:        }
                    648:
                    649:        /* Find a free hash slot (empty or deleted), and add the entry. */
                    650:        slot = ufsdirhash_hash(dh, dirp->d_name, dirp->d_namlen);
                    651:        while (DH_ENTRY(dh, slot) >= 0)
                    652:                slot = WRAPINCR(slot, dh->dh_hlen);
                    653:        if (DH_ENTRY(dh, slot) == DIRHASH_EMPTY)
                    654:                dh->dh_hused++;
                    655:        DH_ENTRY(dh, slot) = offset;
                    656:
                    657:        /* Update the per-block summary info. */
                    658:        ufsdirhash_adjfree(dh, offset, -DIRSIZ(0, dirp, needswap), dirblksiz);
                    659:        DIRHASH_UNLOCK(dh);
                    660: }
                    661:
                    662: /*
                    663:  * Remove the specified directory entry from the hash. The entry to remove
                    664:  * is defined by the name in `dirp', which must exist at the specified
                    665:  * `offset' within the directory.
                    666:  */
                    667: void
                    668: ufsdirhash_remove(struct inode *ip, struct direct *dirp, doff_t offset)
                    669: {
                    670:        struct dirhash *dh;
                    671:        int slot;
                    672:        const int needswap = UFS_MPNEEDSWAP(ip->i_ump);
                    673:        int dirblksiz = ip->i_ump->um_dirblksiz;
                    674:
                    675:        if ((dh = ip->i_dirhash) == NULL)
                    676:                return;
1.21.10.1! yamt      677:
1.1       rumble    678:        DIRHASH_LOCK(dh);
                    679:        if (dh->dh_hash == NULL) {
                    680:                DIRHASH_UNLOCK(dh);
                    681:                ufsdirhash_free(ip);
                    682:                return;
                    683:        }
                    684:
                    685:        KASSERT(offset < dh->dh_dirblks * dirblksiz);
                    686:        /* Find the entry */
                    687:        slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, offset);
                    688:
                    689:        /* Remove the hash entry. */
                    690:        ufsdirhash_delslot(dh, slot);
                    691:
                    692:        /* Update the per-block summary info. */
                    693:        ufsdirhash_adjfree(dh, offset, DIRSIZ(0, dirp, needswap), dirblksiz);
                    694:        DIRHASH_UNLOCK(dh);
                    695: }
                    696:
                    697: /*
                    698:  * Change the offset associated with a directory entry in the hash. Used
                    699:  * when compacting directory blocks.
                    700:  */
                    701: void
                    702: ufsdirhash_move(struct inode *ip, struct direct *dirp, doff_t oldoff,
                    703:     doff_t newoff)
                    704: {
                    705:        struct dirhash *dh;
                    706:        int slot;
                    707:
                    708:        if ((dh = ip->i_dirhash) == NULL)
                    709:                return;
                    710:        DIRHASH_LOCK(dh);
                    711:        if (dh->dh_hash == NULL) {
                    712:                DIRHASH_UNLOCK(dh);
                    713:                ufsdirhash_free(ip);
                    714:                return;
                    715:        }
                    716:
                    717:        KASSERT(oldoff < dh->dh_dirblks * ip->i_ump->um_dirblksiz &&
                    718:            newoff < dh->dh_dirblks * ip->i_ump->um_dirblksiz);
                    719:        /* Find the entry, and update the offset. */
                    720:        slot = ufsdirhash_findslot(dh, dirp->d_name, dirp->d_namlen, oldoff);
                    721:        DH_ENTRY(dh, slot) = newoff;
                    722:        DIRHASH_UNLOCK(dh);
                    723: }
                    724:
                    725: /*
                    726:  * Inform dirhash that the directory has grown by one block that
                    727:  * begins at offset (i.e. the new length is offset + DIRBLKSIZ).
                    728:  */
                    729: void
                    730: ufsdirhash_newblk(struct inode *ip, doff_t offset)
                    731: {
                    732:        struct dirhash *dh;
                    733:        int block;
                    734:        int dirblksiz = ip->i_ump->um_dirblksiz;
                    735:
                    736:        if ((dh = ip->i_dirhash) == NULL)
                    737:                return;
                    738:        DIRHASH_LOCK(dh);
                    739:        if (dh->dh_hash == NULL) {
                    740:                DIRHASH_UNLOCK(dh);
                    741:                ufsdirhash_free(ip);
                    742:                return;
                    743:        }
                    744:
                    745:        KASSERT(offset == dh->dh_dirblks * dirblksiz);
                    746:        block = offset / dirblksiz;
                    747:        if (block >= dh->dh_nblk) {
                    748:                /* Out of space; must rebuild. */
                    749:                DIRHASH_UNLOCK(dh);
                    750:                ufsdirhash_free(ip);
                    751:                return;
                    752:        }
                    753:        dh->dh_dirblks = block + 1;
                    754:
                    755:        /* Account for the new free block. */
                    756:        dh->dh_blkfree[block] = dirblksiz / DIRALIGN;
                    757:        if (dh->dh_firstfree[DH_NFSTATS] == -1)
                    758:                dh->dh_firstfree[DH_NFSTATS] = block;
                    759:        DIRHASH_UNLOCK(dh);
                    760: }
                    761:
                    762: /*
                    763:  * Inform dirhash that the directory is being truncated.
                    764:  */
                    765: void
                    766: ufsdirhash_dirtrunc(struct inode *ip, doff_t offset)
                    767: {
                    768:        struct dirhash *dh;
                    769:        int block, i;
                    770:        int dirblksiz = ip->i_ump->um_dirblksiz;
                    771:
                    772:        if ((dh = ip->i_dirhash) == NULL)
                    773:                return;
1.21.10.1! yamt      774:
1.1       rumble    775:        DIRHASH_LOCK(dh);
                    776:        if (dh->dh_hash == NULL) {
                    777:                DIRHASH_UNLOCK(dh);
                    778:                ufsdirhash_free(ip);
                    779:                return;
                    780:        }
                    781:
                    782:        KASSERT(offset <= dh->dh_dirblks * dirblksiz);
                    783:        block = howmany(offset, dirblksiz);
                    784:        /*
                    785:         * If the directory shrinks to less than 1/8 of dh_nblk blocks
                    786:         * (about 20% of its original size due to the 50% extra added in
                    787:         * ufsdirhash_build) then free it, and let the caller rebuild
                    788:         * if necessary.
                    789:         */
                    790:        if (block < dh->dh_nblk / 8 && dh->dh_narrays > 1) {
                    791:                DIRHASH_UNLOCK(dh);
                    792:                ufsdirhash_free(ip);
                    793:                return;
                    794:        }
                    795:
                    796:        /*
                    797:         * Remove any `first free' information pertaining to the
                    798:         * truncated blocks. All blocks we're removing should be
                    799:         * completely unused.
                    800:         */
                    801:        if (dh->dh_firstfree[DH_NFSTATS] >= block)
                    802:                dh->dh_firstfree[DH_NFSTATS] = -1;
                    803:        for (i = block; i < dh->dh_dirblks; i++)
                    804:                if (dh->dh_blkfree[i] != dirblksiz / DIRALIGN)
                    805:                        panic("ufsdirhash_dirtrunc: blocks in use");
                    806:        for (i = 0; i < DH_NFSTATS; i++)
                    807:                if (dh->dh_firstfree[i] >= block)
                    808:                        panic("ufsdirhash_dirtrunc: first free corrupt");
                    809:        dh->dh_dirblks = block;
                    810:        DIRHASH_UNLOCK(dh);
                    811: }
                    812:
                    813: /*
                    814:  * Debugging function to check that the dirhash information about
                    815:  * a directory block matches its actual contents. Panics if a mismatch
                    816:  * is detected.
                    817:  *
1.3       christos  818:  * On entry, `sbuf' should point to the start of an in-core
1.1       rumble    819:  * DIRBLKSIZ-sized directory block, and `offset' should contain the
                    820:  * offset from the start of the directory of that block.
                    821:  */
                    822: void
1.3       christos  823: ufsdirhash_checkblock(struct inode *ip, char *sbuf, doff_t offset)
1.1       rumble    824: {
                    825:        struct dirhash *dh;
                    826:        struct direct *dp;
                    827:        int block, ffslot, i, nfree;
                    828:        const int needswap = UFS_MPNEEDSWAP(ip->i_ump);
                    829:        int dirblksiz = ip->i_ump->um_dirblksiz;
                    830:
                    831:        if (!ufs_dirhashcheck)
                    832:                return;
                    833:        if ((dh = ip->i_dirhash) == NULL)
                    834:                return;
1.21.10.1! yamt      835:
1.1       rumble    836:        DIRHASH_LOCK(dh);
                    837:        if (dh->dh_hash == NULL) {
                    838:                DIRHASH_UNLOCK(dh);
                    839:                ufsdirhash_free(ip);
                    840:                return;
                    841:        }
                    842:
                    843:        block = offset / dirblksiz;
                    844:        if ((offset & (dirblksiz - 1)) != 0 || block >= dh->dh_dirblks)
                    845:                panic("ufsdirhash_checkblock: bad offset");
                    846:
                    847:        nfree = 0;
                    848:        for (i = 0; i < dirblksiz; i += dp->d_reclen) {
1.3       christos  849:                dp = (struct direct *)(sbuf + i);
1.1       rumble    850:                if (dp->d_reclen == 0 || i + dp->d_reclen > dirblksiz)
                    851:                        panic("ufsdirhash_checkblock: bad dir");
                    852:
                    853:                if (dp->d_ino == 0) {
                    854: #if 0
                    855:                        /*
                    856:                         * XXX entries with d_ino == 0 should only occur
                    857:                         * at the start of a DIRBLKSIZ block. However the
                    858:                         * ufs code is tolerant of such entries at other
                    859:                         * offsets, and fsck does not fix them.
                    860:                         */
                    861:                        if (i != 0)
                    862:                                panic("ufsdirhash_checkblock: bad dir inode");
                    863: #endif
                    864:                        nfree += dp->d_reclen;
                    865:                        continue;
                    866:                }
                    867:
                    868:                /* Check that the entry exists (will panic if it doesn't). */
                    869:                ufsdirhash_findslot(dh, dp->d_name, dp->d_namlen, offset + i);
                    870:
                    871:                nfree += dp->d_reclen - DIRSIZ(0, dp, needswap);
                    872:        }
                    873:        if (i != dirblksiz)
                    874:                panic("ufsdirhash_checkblock: bad dir end");
                    875:
                    876:        if (dh->dh_blkfree[block] * DIRALIGN != nfree)
                    877:                panic("ufsdirhash_checkblock: bad free count");
                    878:
                    879:        ffslot = BLKFREE2IDX(nfree / DIRALIGN);
                    880:        for (i = 0; i <= DH_NFSTATS; i++)
                    881:                if (dh->dh_firstfree[i] == block && i != ffslot)
                    882:                        panic("ufsdirhash_checkblock: bad first-free");
                    883:        if (dh->dh_firstfree[ffslot] == -1)
                    884:                panic("ufsdirhash_checkblock: missing first-free entry");
                    885:        DIRHASH_UNLOCK(dh);
                    886: }
                    887:
                    888: /*
                    889:  * Hash the specified filename into a dirhash slot.
                    890:  */
                    891: static int
                    892: ufsdirhash_hash(struct dirhash *dh, const char *name, int namelen)
                    893: {
                    894:        u_int32_t hash;
                    895:
                    896:        /*
                    897:         * We hash the name and then some other bit of data that is
                    898:         * invariant over the dirhash's lifetime. Otherwise names
                    899:         * differing only in the last byte are placed close to one
                    900:         * another in the table, which is bad for linear probing.
                    901:         */
                    902:        hash = hash32_buf(name, namelen, HASH32_BUF_INIT);
                    903:        hash = hash32_buf(&dh, sizeof(dh), hash);
                    904:        return (hash % dh->dh_hlen);
                    905: }
                    906:
                    907: /*
                    908:  * Adjust the number of free bytes in the block containing `offset'
                    909:  * by the value specified by `diff'.
                    910:  *
                    911:  * The caller must ensure we have exclusive access to `dh'; normally
1.16      ad        912:  * that means that dh_lock should be held, but this is also called
1.1       rumble    913:  * from ufsdirhash_build() where exclusive access can be assumed.
                    914:  */
                    915: static void
                    916: ufsdirhash_adjfree(struct dirhash *dh, doff_t offset, int diff, int dirblksiz)
                    917: {
                    918:        int block, i, nfidx, ofidx;
                    919:
1.21.10.1! yamt      920:        KASSERT(mutex_owned(&dh->dh_lock));
        !           921:
1.1       rumble    922:        /* Update the per-block summary info. */
                    923:        block = offset / dirblksiz;
                    924:        KASSERT(block < dh->dh_nblk && block < dh->dh_dirblks);
                    925:        ofidx = BLKFREE2IDX(dh->dh_blkfree[block]);
                    926:        dh->dh_blkfree[block] = (int)dh->dh_blkfree[block] + (diff / DIRALIGN);
                    927:        nfidx = BLKFREE2IDX(dh->dh_blkfree[block]);
                    928:
                    929:        /* Update the `first free' list if necessary. */
                    930:        if (ofidx != nfidx) {
                    931:                /* If removing, scan forward for the next block. */
                    932:                if (dh->dh_firstfree[ofidx] == block) {
                    933:                        for (i = block + 1; i < dh->dh_dirblks; i++)
                    934:                                if (BLKFREE2IDX(dh->dh_blkfree[i]) == ofidx)
                    935:                                        break;
                    936:                        dh->dh_firstfree[ofidx] = (i < dh->dh_dirblks) ? i : -1;
                    937:                }
                    938:
                    939:                /* Make this the new `first free' if necessary */
                    940:                if (dh->dh_firstfree[nfidx] > block ||
                    941:                    dh->dh_firstfree[nfidx] == -1)
                    942:                        dh->dh_firstfree[nfidx] = block;
                    943:        }
                    944: }
                    945:
                    946: /*
                    947:  * Find the specified name which should have the specified offset.
                    948:  * Returns a slot number, and panics on failure.
                    949:  *
                    950:  * `dh' must be locked on entry and remains so on return.
                    951:  */
                    952: static int
                    953: ufsdirhash_findslot(struct dirhash *dh, const char *name, int namelen,
                    954:     doff_t offset)
                    955: {
                    956:        int slot;
                    957:
1.16      ad        958:        KASSERT(mutex_owned(&dh->dh_lock));
                    959:
1.1       rumble    960:        /* Find the entry. */
                    961:        KASSERT(dh->dh_hused < dh->dh_hlen);
                    962:        slot = ufsdirhash_hash(dh, name, namelen);
                    963:        while (DH_ENTRY(dh, slot) != offset &&
                    964:            DH_ENTRY(dh, slot) != DIRHASH_EMPTY)
                    965:                slot = WRAPINCR(slot, dh->dh_hlen);
                    966:        if (DH_ENTRY(dh, slot) != offset)
                    967:                panic("ufsdirhash_findslot: '%.*s' not found", namelen, name);
                    968:
                    969:        return (slot);
                    970: }
                    971:
                    972: /*
                    973:  * Remove the entry corresponding to the specified slot from the hash array.
                    974:  *
                    975:  * `dh' must be locked on entry and remains so on return.
                    976:  */
                    977: static void
                    978: ufsdirhash_delslot(struct dirhash *dh, int slot)
                    979: {
                    980:        int i;
                    981:
1.16      ad        982:        KASSERT(mutex_owned(&dh->dh_lock));
                    983:
1.1       rumble    984:        /* Mark the entry as deleted. */
                    985:        DH_ENTRY(dh, slot) = DIRHASH_DEL;
                    986:
                    987:        /* If this is the end of a chain of DIRHASH_DEL slots, remove them. */
                    988:        for (i = slot; DH_ENTRY(dh, i) == DIRHASH_DEL; )
                    989:                i = WRAPINCR(i, dh->dh_hlen);
                    990:        if (DH_ENTRY(dh, i) == DIRHASH_EMPTY) {
                    991:                i = WRAPDECR(i, dh->dh_hlen);
                    992:                while (DH_ENTRY(dh, i) == DIRHASH_DEL) {
                    993:                        DH_ENTRY(dh, i) = DIRHASH_EMPTY;
                    994:                        dh->dh_hused--;
                    995:                        i = WRAPDECR(i, dh->dh_hlen);
                    996:                }
                    997:                KASSERT(dh->dh_hused >= 0);
                    998:        }
                    999: }
                   1000:
                   1001: /*
                   1002:  * Given a directory entry and its offset, find the offset of the
                   1003:  * previous entry in the same DIRBLKSIZ-sized block. Returns an
                   1004:  * offset, or -1 if there is no previous entry in the block or some
                   1005:  * other problem occurred.
                   1006:  */
                   1007: static doff_t
                   1008: ufsdirhash_getprev(struct direct *dirp, doff_t offset, int dirblksiz)
                   1009: {
                   1010:        struct direct *dp;
                   1011:        char *blkbuf;
                   1012:        doff_t blkoff, prevoff;
                   1013:        int entrypos, i;
                   1014:
                   1015:        blkoff = offset & ~(dirblksiz - 1);     /* offset of start of block */
                   1016:        entrypos = offset & (dirblksiz - 1);    /* entry relative to block */
                   1017:        blkbuf = (char *)dirp - entrypos;
                   1018:        prevoff = blkoff;
                   1019:
                   1020:        /* If `offset' is the start of a block, there is no previous entry. */
                   1021:        if (entrypos == 0)
                   1022:                return (-1);
                   1023:
                   1024:        /* Scan from the start of the block until we get to the entry. */
                   1025:        for (i = 0; i < entrypos; i += dp->d_reclen) {
                   1026:                dp = (struct direct *)(blkbuf + i);
                   1027:                if (dp->d_reclen == 0 || i + dp->d_reclen > entrypos)
                   1028:                        return (-1);    /* Corrupted directory. */
                   1029:                prevoff = blkoff + i;
                   1030:        }
                   1031:        return (prevoff);
                   1032: }
                   1033:
                   1034: /*
                   1035:  * Try to free up `wanted' bytes by stealing memory from existing
                   1036:  * dirhashes. Returns zero with list locked if successful.
                   1037:  */
                   1038: static int
                   1039: ufsdirhash_recycle(int wanted)
                   1040: {
                   1041:        struct dirhash *dh;
                   1042:        doff_t **hash;
                   1043:        u_int8_t *blkfree;
                   1044:        int i, mem, narrays;
1.21.10.1! yamt     1045:        size_t hashsz, blkfreesz;
1.1       rumble   1046:
                   1047:        DIRHASHLIST_LOCK();
                   1048:        while (wanted + ufs_dirhashmem > ufs_dirhashmaxmem) {
                   1049:                /* Find a dirhash, and lock it. */
                   1050:                if ((dh = TAILQ_FIRST(&ufsdirhash_list)) == NULL) {
                   1051:                        DIRHASHLIST_UNLOCK();
                   1052:                        return (-1);
                   1053:                }
                   1054:                DIRHASH_LOCK(dh);
                   1055:                KASSERT(dh->dh_hash != NULL);
                   1056:
                   1057:                /* Decrement the score; only recycle if it becomes zero. */
                   1058:                if (--dh->dh_score > 0) {
                   1059:                        DIRHASH_UNLOCK(dh);
                   1060:                        DIRHASHLIST_UNLOCK();
                   1061:                        return (-1);
                   1062:                }
                   1063:
                   1064:                /* Remove it from the list and detach its memory. */
                   1065:                TAILQ_REMOVE(&ufsdirhash_list, dh, dh_list);
                   1066:                dh->dh_onlist = 0;
                   1067:                hash = dh->dh_hash;
1.21.10.1! yamt     1068:                hashsz = dh->dh_hashsz;
1.1       rumble   1069:                dh->dh_hash = NULL;
                   1070:                blkfree = dh->dh_blkfree;
1.21.10.1! yamt     1071:                blkfreesz = dh->dh_blkfreesz;
1.1       rumble   1072:                dh->dh_blkfree = NULL;
                   1073:                narrays = dh->dh_narrays;
                   1074:                mem = narrays * sizeof(*dh->dh_hash) +
                   1075:                    narrays * DH_NBLKOFF * sizeof(**dh->dh_hash) +
                   1076:                    dh->dh_nblk * sizeof(*dh->dh_blkfree);
                   1077:
                   1078:                /* Unlock everything, free the detached memory. */
                   1079:                DIRHASH_UNLOCK(dh);
                   1080:                DIRHASHLIST_UNLOCK();
1.21.10.1! yamt     1081:
1.1       rumble   1082:                for (i = 0; i < narrays; i++)
                   1083:                        DIRHASH_BLKFREE(hash[i]);
1.21.10.1! yamt     1084:                kmem_free(hash, hashsz);
        !          1085:                kmem_free(blkfree, blkfreesz);
1.1       rumble   1086:
                   1087:                /* Account for the returned memory, and repeat if necessary. */
                   1088:                DIRHASHLIST_LOCK();
                   1089:                ufs_dirhashmem -= mem;
                   1090:        }
1.21.10.1! yamt     1091:        /* Success. */
1.1       rumble   1092:        return (0);
                   1093: }
                   1094:
1.21.10.1! yamt     1095: static void
        !          1096: ufsdirhash_sysctl_init(void)
1.1       rumble   1097: {
1.4       atatat   1098:        const struct sysctlnode *rnode, *cnode;
1.1       rumble   1099:
1.21.10.1! yamt     1100:        sysctl_createv(&ufsdirhash_sysctl_log, 0, NULL, &rnode,
1.1       rumble   1101:                       CTLFLAG_PERMANENT,
                   1102:                       CTLTYPE_NODE, "vfs", NULL,
                   1103:                       NULL, 0, NULL, 0,
                   1104:                       CTL_VFS, CTL_EOL);
                   1105:
1.21.10.1! yamt     1106:        sysctl_createv(&ufsdirhash_sysctl_log, 0, &rnode, &rnode,
1.1       rumble   1107:                       CTLFLAG_PERMANENT,
                   1108:                       CTLTYPE_NODE, "ufs",
                   1109:                       SYSCTL_DESCR("ufs"),
                   1110:                       NULL, 0, NULL, 0,
                   1111:                       CTL_CREATE, CTL_EOL);
                   1112:
1.21.10.1! yamt     1113:        sysctl_createv(&ufsdirhash_sysctl_log, 0, &rnode, &rnode,
1.1       rumble   1114:                       CTLFLAG_PERMANENT,
                   1115:                       CTLTYPE_NODE, "dirhash",
                   1116:                       SYSCTL_DESCR("dirhash"),
                   1117:                       NULL, 0, NULL, 0,
                   1118:                       CTL_CREATE, CTL_EOL);
                   1119:
1.21.10.1! yamt     1120:        sysctl_createv(&ufsdirhash_sysctl_log, 0, &rnode, &cnode,
1.1       rumble   1121:                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                   1122:                       CTLTYPE_INT, "minblocks",
                   1123:                       SYSCTL_DESCR("minimum hashed directory size in blocks"),
                   1124:                       NULL, 0, &ufs_dirhashminblks, 0,
                   1125:                       CTL_CREATE, CTL_EOL);
                   1126:
1.21.10.1! yamt     1127:        sysctl_createv(&ufsdirhash_sysctl_log, 0, &rnode, &cnode,
1.1       rumble   1128:                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                   1129:                       CTLTYPE_INT, "maxmem",
                   1130:                       SYSCTL_DESCR("maximum dirhash memory usage"),
                   1131:                       NULL, 0, &ufs_dirhashmaxmem, 0,
                   1132:                       CTL_CREATE, CTL_EOL);
                   1133:
1.21.10.1! yamt     1134:        sysctl_createv(&ufsdirhash_sysctl_log, 0, &rnode, &cnode,
1.1       rumble   1135:                       CTLFLAG_PERMANENT|CTLFLAG_READONLY,
                   1136:                       CTLTYPE_INT, "memused",
                   1137:                       SYSCTL_DESCR("current dirhash memory usage"),
                   1138:                       NULL, 0, &ufs_dirhashmem, 0,
                   1139:                       CTL_CREATE, CTL_EOL);
                   1140:
1.21.10.1! yamt     1141:        sysctl_createv(&ufsdirhash_sysctl_log, 0, &rnode, &cnode,
1.1       rumble   1142:                       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
                   1143:                       CTLTYPE_INT, "docheck",
                   1144:                       SYSCTL_DESCR("enable extra sanity checks"),
                   1145:                       NULL, 0, &ufs_dirhashcheck, 0,
                   1146:                       CTL_CREATE, CTL_EOL);
                   1147: }
1.21.10.1! yamt     1148:
        !          1149: void
        !          1150: ufsdirhash_init(void)
        !          1151: {
        !          1152:
        !          1153:        mutex_init(&ufsdirhash_lock, MUTEX_DEFAULT, IPL_NONE);
        !          1154:        ufsdirhashblk_cache = pool_cache_init(DH_NBLKOFF * sizeof(daddr_t), 0,
        !          1155:            0, 0, "dirhashblk", NULL, IPL_NONE, NULL, NULL, NULL);
        !          1156:        ufsdirhash_cache = pool_cache_init(sizeof(struct dirhash), 0,
        !          1157:            0, 0, "dirhash", NULL, IPL_NONE, NULL, NULL, NULL);
        !          1158:        TAILQ_INIT(&ufsdirhash_list);
        !          1159:        ufsdirhash_sysctl_init();
        !          1160: }
        !          1161:
        !          1162: void
        !          1163: ufsdirhash_done(void)
        !          1164: {
        !          1165:
        !          1166:        KASSERT(TAILQ_EMPTY(&ufsdirhash_list));
        !          1167:        pool_cache_destroy(ufsdirhashblk_cache);
        !          1168:        pool_cache_destroy(ufsdirhash_cache);
        !          1169:        mutex_destroy(&ufsdirhash_lock);
        !          1170:        sysctl_teardown(&ufsdirhash_sysctl_log);
        !          1171: }

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