dmake: do not set MAKEFLAGS=k

[unleashed/tickless.git] / kernel / fs / ufs / lufs.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/systm.h>
#include <sys/types.h>
#include <sys/vnode.h>
#include <sys/buf.h>
#include <sys/errno.h>
#include <sys/fssnap_if.h>
#include <sys/fs/ufs_inode.h>
#include <sys/fs/ufs_filio.h>
#include <sys/sysmacros.h>
#include <sys/modctl.h>
#include <sys/fs/ufs_log.h>
#include <sys/fs/ufs_bio.h>
#include <sys/fs/ufs_fsdir.h>
#include <sys/debug.h>
#include <sys/atomic.h>
#include <sys/kmem.h>
#include <sys/inttypes.h>
#include <sys/vfs.h>
#include <sys/mntent.h>
#include <sys/conf.h>
#include <sys/param.h>
#include <sys/kstat.h>
#include <sys/cmn_err.h>
#include <sys/sdt.h>

#define LUFS_GENID_PRIME        UINT64_C(4294967291)
#define LUFS_GENID_BASE         UINT64_C(311)
#define LUFS_NEXT_ID(id)        ((uint32_t)(((id) * LUFS_GENID_BASE) % \
                                    LUFS_GENID_PRIME))

extern  kmutex_t        ufs_scan_lock;

static kmutex_t log_mutex;      /* general purpose log layer lock */
kmutex_t        ml_scan;        /* Scan thread syncronization */
kcondvar_t      ml_scan_cv;     /* Scan thread syncronization */

struct kmem_cache       *lufs_sv;
struct kmem_cache       *lufs_bp;

/* Tunables */
uint_t          ldl_maxlogsize  = LDL_MAXLOGSIZE;
uint_t          ldl_minlogsize  = LDL_MINLOGSIZE;
uint_t          ldl_softlogcap  = LDL_SOFTLOGCAP;
uint32_t        ldl_divisor     = LDL_DIVISOR;
uint32_t        ldl_mintransfer = LDL_MINTRANSFER;
uint32_t        ldl_maxtransfer = LDL_MAXTRANSFER;
uint32_t        ldl_minbufsize  = LDL_MINBUFSIZE;
uint32_t        ldl_cgsizereq   = 0;

/* Generation of header ids */
static kmutex_t genid_mutex;
static uint32_t last_loghead_ident = UINT32_C(0);

/*
 * Logging delta and roll statistics
 */
struct delta_kstats {
        kstat_named_t ds_superblock_deltas;
        kstat_named_t ds_bitmap_deltas;
        kstat_named_t ds_suminfo_deltas;
        kstat_named_t ds_allocblk_deltas;
        kstat_named_t ds_ab0_deltas;
        kstat_named_t ds_dir_deltas;
        kstat_named_t ds_inode_deltas;
        kstat_named_t ds_fbiwrite_deltas;
        kstat_named_t ds_quota_deltas;
        kstat_named_t ds_shadow_deltas;

        kstat_named_t ds_superblock_rolled;
        kstat_named_t ds_bitmap_rolled;
        kstat_named_t ds_suminfo_rolled;
        kstat_named_t ds_allocblk_rolled;
        kstat_named_t ds_ab0_rolled;
        kstat_named_t ds_dir_rolled;
        kstat_named_t ds_inode_rolled;
        kstat_named_t ds_fbiwrite_rolled;
        kstat_named_t ds_quota_rolled;
        kstat_named_t ds_shadow_rolled;
} dkstats = {
        { "superblock_deltas",  KSTAT_DATA_UINT64 },
        { "bitmap_deltas",      KSTAT_DATA_UINT64 },
        { "suminfo_deltas",     KSTAT_DATA_UINT64 },
        { "allocblk_deltas",    KSTAT_DATA_UINT64 },
        { "ab0_deltas",         KSTAT_DATA_UINT64 },
        { "dir_deltas",         KSTAT_DATA_UINT64 },
        { "inode_deltas",       KSTAT_DATA_UINT64 },
        { "fbiwrite_deltas",    KSTAT_DATA_UINT64 },
        { "quota_deltas",       KSTAT_DATA_UINT64 },
        { "shadow_deltas",      KSTAT_DATA_UINT64 },

        { "superblock_rolled",  KSTAT_DATA_UINT64 },
        { "bitmap_rolled",      KSTAT_DATA_UINT64 },
        { "suminfo_rolled",     KSTAT_DATA_UINT64 },
        { "allocblk_rolled",    KSTAT_DATA_UINT64 },
        { "ab0_rolled",         KSTAT_DATA_UINT64 },
        { "dir_rolled",         KSTAT_DATA_UINT64 },
        { "inode_rolled",       KSTAT_DATA_UINT64 },
        { "fbiwrite_rolled",    KSTAT_DATA_UINT64 },
        { "quota_rolled",       KSTAT_DATA_UINT64 },
        { "shadow_rolled",      KSTAT_DATA_UINT64 }
};

uint64_t delta_stats[DT_MAX];
uint64_t roll_stats[DT_MAX];

/*
 * General logging kstats
 */
struct logstats logstats = {
        { "master_reads",               KSTAT_DATA_UINT64 },
        { "master_writes",              KSTAT_DATA_UINT64 },
        { "log_reads_inmem",            KSTAT_DATA_UINT64 },
        { "log_reads",                  KSTAT_DATA_UINT64 },
        { "log_writes",                 KSTAT_DATA_UINT64 },
        { "log_master_reads",           KSTAT_DATA_UINT64 },
        { "log_roll_reads",             KSTAT_DATA_UINT64 },
        { "log_roll_writes",            KSTAT_DATA_UINT64 }
};

int
trans_not_done(struct buf *cb)
{
        sema_v(&cb->b_io);
        return (0);
}

static void
trans_wait_panic(struct buf *cb)
{
        while ((cb->b_flags & B_DONE) == 0)
                drv_usecwait(10);
}

int
trans_not_wait(struct buf *cb)
{
        /*
         * In case of panic, busy wait for completion
         */
        if (panicstr)
                trans_wait_panic(cb);
        else
                sema_p(&cb->b_io);

        return (geterror(cb));
}

int
trans_wait(struct buf *cb)
{
        /*
         * In case of panic, busy wait for completion and run md daemon queues
         */
        if (panicstr)
                trans_wait_panic(cb);
        return (biowait(cb));
}

static void
setsum(int32_t *sp, int32_t *lp, int nb)
{
        int32_t csum = 0;

        *sp = 0;
        nb /= sizeof (int32_t);
        while (nb--)
                csum += *lp++;
        *sp = csum;
}

static int
checksum(int32_t *sp, int32_t *lp, int nb)
{
        int32_t ssum = *sp;

        setsum(sp, lp, nb);
        if (ssum != *sp) {
                *sp = ssum;
                return (0);
        }
        return (1);
}

void
lufs_unsnarf(ufsvfs_t *ufsvfsp)
{
        ml_unit_t *ul;
        mt_map_t *mtm;

        ul = ufsvfsp->vfs_log;
        if (ul == NULL)
                return;

        mtm = ul->un_logmap;

        /*
         * Wait for a pending top_issue_sync which is
         * dispatched (via taskq_dispatch()) but hasnt completed yet.
         */

        mutex_enter(&mtm->mtm_lock);

        while (mtm->mtm_taskq_sync_count != 0) {
                cv_wait(&mtm->mtm_cv, &mtm->mtm_lock);
        }

        mutex_exit(&mtm->mtm_lock);

        /* Roll committed transactions */
        logmap_roll_dev(ul);

        /* Kill the roll thread */
        logmap_kill_roll(ul);

        /* release saved alloction info */
        if (ul->un_ebp)
                kmem_free(ul->un_ebp, ul->un_nbeb);

        /* release circular bufs */
        free_cirbuf(&ul->un_rdbuf);
        free_cirbuf(&ul->un_wrbuf);

        /* release maps */
        if (ul->un_logmap)
                ul->un_logmap = map_put(ul->un_logmap);
        if (ul->un_deltamap)
                ul->un_deltamap = map_put(ul->un_deltamap);
        if (ul->un_matamap)
                ul->un_matamap = map_put(ul->un_matamap);

        mutex_destroy(&ul->un_log_mutex);
        mutex_destroy(&ul->un_state_mutex);

        /* release state buffer MUST BE LAST!! (contains our ondisk data) */
        if (ul->un_bp)
                brelse(ul->un_bp);
        kmem_free(ul, sizeof (*ul));

        ufsvfsp->vfs_log = NULL;
}

int
lufs_snarf(ufsvfs_t *ufsvfsp, struct fs *fs, int ronly)
{
        buf_t           *bp, *tbp;
        ml_unit_t       *ul;
        extent_block_t  *ebp;
        ic_extent_block_t  *nebp;
        size_t          nb;
        daddr_t         bno;    /* in disk blocks */
        int             i;

        /* LINTED: warning: logical expression always true: op "||" */
        ASSERT(sizeof (ml_odunit_t) < DEV_BSIZE);

        /*
         * Get the allocation table
         *      During a remount the superblock pointed to by the ufsvfsp
         *      is out of date.  Hence the need for the ``new'' superblock
         *      pointer, fs, passed in as a parameter.
         */
        bp = UFS_BREAD(ufsvfsp, ufsvfsp->vfs_dev, logbtodb(fs, fs->fs_logbno),
            fs->fs_bsize);
        if (bp->b_flags & B_ERROR) {
                brelse(bp);
                return (EIO);
        }
        ebp = (void *)bp->b_un.b_addr;
        if (!checksum(&ebp->chksum, (int32_t *)bp->b_un.b_addr,
            fs->fs_bsize)) {
                brelse(bp);
                return (ENODEV);
        }

        /*
         * It is possible to get log blocks with all zeros.
         * We should also check for nextents to be zero in such case.
         */
        if (ebp->type != LUFS_EXTENTS || ebp->nextents == 0) {
                brelse(bp);
                return (EDOM);
        }
        /*
         * Put allocation into memory.  This requires conversion between
         * on the ondisk format of the extent (type extent_t) and the
         * in-core format of the extent (type ic_extent_t).  The
         * difference is the in-core form of the extent block stores
         * the physical offset of the extent in disk blocks, which
         * can require more than a 32-bit field.
         */
        nb = (size_t)(sizeof (ic_extent_block_t) +
            ((ebp->nextents - 1) * sizeof (ic_extent_t)));
        nebp = kmem_alloc(nb, KM_SLEEP);
        nebp->ic_nextents = ebp->nextents;
        nebp->ic_nbytes = ebp->nbytes;
        nebp->ic_nextbno = ebp->nextbno;
        for (i = 0; i < ebp->nextents; i++) {
                nebp->ic_extents[i].ic_lbno = ebp->extents[i].lbno;
                nebp->ic_extents[i].ic_nbno = ebp->extents[i].nbno;
                nebp->ic_extents[i].ic_pbno =
                    logbtodb(fs, ebp->extents[i].pbno);
        }
        brelse(bp);

        /*
         * Get the log state
         */
        bno = nebp->ic_extents[0].ic_pbno;
        bp = UFS_BREAD(ufsvfsp, ufsvfsp->vfs_dev, bno, DEV_BSIZE);
        if (bp->b_flags & B_ERROR) {
                brelse(bp);
                bp = UFS_BREAD(ufsvfsp, ufsvfsp->vfs_dev, bno + 1, DEV_BSIZE);
                if (bp->b_flags & B_ERROR) {
                        brelse(bp);
                        kmem_free(nebp, nb);
                        return (EIO);
                }
        }

        /*
         * Put ondisk struct into an anonymous buffer
         *      This buffer will contain the memory for the ml_odunit struct
         */
        tbp = ngeteblk(dbtob(LS_SECTORS));
        tbp->b_edev = bp->b_edev;
        tbp->b_dev = bp->b_dev;
        tbp->b_blkno = bno;
        bcopy(bp->b_un.b_addr, tbp->b_un.b_addr, DEV_BSIZE);
        bcopy(bp->b_un.b_addr, tbp->b_un.b_addr + DEV_BSIZE, DEV_BSIZE);
        bp->b_flags |= (B_STALE | B_AGE);
        brelse(bp);
        bp = tbp;

        /*
         * Verify the log state
         *
         * read/only mounts w/bad logs are allowed.  umount will
         * eventually roll the bad log until the first IO error.
         * fsck will then repair the file system.
         *
         * read/write mounts with bad logs are not allowed.
         *
         */
        ul = (ml_unit_t *)kmem_zalloc(sizeof (*ul), KM_SLEEP);
        bcopy(bp->b_un.b_addr, &ul->un_ondisk, sizeof (ml_odunit_t));
        if ((ul->un_chksum != ul->un_head_ident + ul->un_tail_ident) ||
            (ul->un_version != LUFS_VERSION_LATEST) ||
            (!ronly && ul->un_badlog)) {
                kmem_free(ul, sizeof (*ul));
                brelse(bp);
                kmem_free(nebp, nb);
                return (EIO);
        }
        /*
         * Initialize the incore-only fields
         */
        if (ronly)
                ul->un_flags |= LDL_NOROLL;
        ul->un_bp = bp;
        ul->un_ufsvfs = ufsvfsp;
        ul->un_dev = ufsvfsp->vfs_dev;
        ul->un_ebp = nebp;
        ul->un_nbeb = nb;
        ul->un_maxresv = btodb(ul->un_logsize) * LDL_USABLE_BSIZE;
        ul->un_deltamap = map_get(ul, deltamaptype, DELTAMAP_NHASH);
        ul->un_logmap = map_get(ul, logmaptype, LOGMAP_NHASH);
        if (ul->un_debug & MT_MATAMAP)
                ul->un_matamap = map_get(ul, matamaptype, DELTAMAP_NHASH);
        mutex_init(&ul->un_log_mutex, NULL, MUTEX_DEFAULT, NULL);
        mutex_init(&ul->un_state_mutex, NULL, MUTEX_DEFAULT, NULL);

        /*
         * Aquire the ufs_scan_lock before linking the mtm data
         * structure so that we keep ufs_sync() and ufs_update() away
         * when they execute the ufs_scan_inodes() run while we're in
         * progress of enabling/disabling logging.
         */
        mutex_enter(&ufs_scan_lock);
        ufsvfsp->vfs_log = ul;

        /* remember the state of the log before the log scan */
        logmap_logscan(ul);
        mutex_exit(&ufs_scan_lock);

        /*
         * Error during scan
         *
         * If this is a read/only mount; ignore the error.
         * At a later time umount/fsck will repair the fs.
         *
         */
        if (ul->un_flags & LDL_ERROR) {
                if (!ronly) {
                        /*
                         * Aquire the ufs_scan_lock before de-linking
                         * the mtm data structure so that we keep ufs_sync()
                         * and ufs_update() away when they execute the
                         * ufs_scan_inodes() run while we're in progress of
                         * enabling/disabling logging.
                         */
                        mutex_enter(&ufs_scan_lock);
                        lufs_unsnarf(ufsvfsp);
                        mutex_exit(&ufs_scan_lock);
                        return (EIO);
                }
                ul->un_flags &= ~LDL_ERROR;
        }
        if (!ronly)
                logmap_start_roll(ul);
        return (0);
}

uint32_t
lufs_hd_genid(const ml_unit_t *up)
{
        uint32_t id;

        mutex_enter(&genid_mutex);

        /*
         * The formula below implements an exponential, modular sequence.
         *
         * ID(N) = (SEED * (BASE^N)) % PRIME
         *
         * The numbers will be pseudo random.  They depend on SEED, BASE, PRIME,
         * but will sweep through almost all of the range 1....PRIME-1.
         * Most  importantly  they  will  not  repeat  for PRIME-2 (4294967289)
         * repetitions.  If they would repeat that  could possibly cause  hangs,
         * panics at mount/umount and failed mount operations.
         */
        id = LUFS_NEXT_ID(last_loghead_ident);

        /* Checking if new identity used already */
        if (up != NULL && up->un_head_ident == id) {
                DTRACE_PROBE1(head_ident_collision, uint32_t, id);

                /*
                 * The  following  preserves  the  algorithm  for  the fix  for
                 * "panic: free: freeing free frag, dev:0x2000000018, blk:34605,
                 * cg:26, ino:148071,".
                 * If  the header identities  un_head_ident  are  equal  to the
                 * present element  in the sequence,  the next element  of  the
                 * sequence is returned instead.
                 */
                id = LUFS_NEXT_ID(id);
        }

        last_loghead_ident = id;

        mutex_exit(&genid_mutex);

        return (id);
}

static void
lufs_genid_init(void)
{
        uint64_t seed;

        /* Initialization */
        mutex_init(&genid_mutex, NULL, MUTEX_DEFAULT, NULL);

        /* Seed the algorithm */
        do {
                timestruc_t tv;

                gethrestime(&tv);

                seed = (tv.tv_nsec << 3);
                seed ^= tv.tv_sec;

                last_loghead_ident = (uint32_t)(seed % LUFS_GENID_PRIME);
        } while (last_loghead_ident == UINT32_C(0));
}

static int
lufs_initialize(
        ufsvfs_t *ufsvfsp,
        daddr_t bno,
        size_t nb,
        struct fiolog *flp)
{
        ml_odunit_t     *ud, *ud2;
        buf_t           *bp;

        /* LINTED: warning: logical expression always true: op "||" */
        ASSERT(sizeof (ml_odunit_t) < DEV_BSIZE);
        ASSERT(nb >= ldl_minlogsize);

        bp = UFS_GETBLK(ufsvfsp, ufsvfsp->vfs_dev, bno, dbtob(LS_SECTORS));
        bzero(bp->b_un.b_addr, bp->b_bcount);

        ud = (void *)bp->b_un.b_addr;
        ud->od_version = LUFS_VERSION_LATEST;
        ud->od_maxtransfer = MIN(ufsvfsp->vfs_iotransz, ldl_maxtransfer);
        if (ud->od_maxtransfer < ldl_mintransfer)
                ud->od_maxtransfer = ldl_mintransfer;
        ud->od_devbsize = DEV_BSIZE;

        ud->od_requestsize = flp->nbytes_actual;
        ud->od_statesize = dbtob(LS_SECTORS);
        ud->od_logsize = nb - ud->od_statesize;

        ud->od_statebno = INT32_C(0);

        ud->od_head_ident = lufs_hd_genid(NULL);
        ud->od_tail_ident = ud->od_head_ident;
        ud->od_chksum = ud->od_head_ident + ud->od_tail_ident;

        ud->od_bol_lof = dbtob(ud->od_statebno) + ud->od_statesize;
        ud->od_eol_lof = ud->od_bol_lof + ud->od_logsize;
        ud->od_head_lof = ud->od_bol_lof;
        ud->od_tail_lof = ud->od_bol_lof;

        ASSERT(lufs_initialize_debug(ud));

        ud2 = (void *)(bp->b_un.b_addr + DEV_BSIZE);
        bcopy(ud, ud2, sizeof (*ud));

        UFS_BWRITE2(ufsvfsp, bp);
        if (bp->b_flags & B_ERROR) {
                brelse(bp);
                return (EIO);
        }
        brelse(bp);

        return (0);
}

/*
 * Free log space
 *      Assumes the file system is write locked and is not logging
 */
static int
lufs_free(struct ufsvfs *ufsvfsp)
{
        int             error = 0, i, j;
        buf_t           *bp = NULL;
        extent_t        *ep;
        extent_block_t  *ebp;
        struct fs       *fs = ufsvfsp->vfs_fs;
        daddr_t         fno;
        int32_t         logbno;
        long            nfno;
        inode_t         *ip = NULL;
        char            clean;

        /*
         * Nothing to free
         */
        if (fs->fs_logbno == 0)
                return (0);

        /*
         * Mark the file system as FSACTIVE and no log but honor the
         * current value of fs_reclaim.  The reclaim thread could have
         * been active when lufs_disable() was called and if fs_reclaim
         * is reset to zero here it could lead to lost inodes.
         */
        ufsvfsp->vfs_ulockfs.ul_sbowner = curthread;
        mutex_enter(&ufsvfsp->vfs_lock);
        clean = fs->fs_clean;
        logbno = fs->fs_logbno;
        fs->fs_clean = FSACTIVE;
        fs->fs_logbno = INT32_C(0);
        ufs_sbwrite(ufsvfsp);
        mutex_exit(&ufsvfsp->vfs_lock);
        ufsvfsp->vfs_ulockfs.ul_sbowner = (kthread_id_t)-1;
        if (ufsvfsp->vfs_bufp->b_flags & B_ERROR) {
                error = EIO;
                fs->fs_clean = clean;
                fs->fs_logbno = logbno;
                goto errout;
        }

        /*
         * fetch the allocation block
         *      superblock -> one block of extents -> log data
         */
        bp = UFS_BREAD(ufsvfsp, ufsvfsp->vfs_dev, logbtodb(fs, logbno),
            fs->fs_bsize);
        if (bp->b_flags & B_ERROR) {
                error = EIO;
                goto errout;
        }

        /*
         * Free up the allocated space (dummy inode needed for free())
         */
        ip = ufs_alloc_inode(ufsvfsp, UFSROOTINO);
        ebp = (void *)bp->b_un.b_addr;
        for (i = 0, ep = &ebp->extents[0]; i < ebp->nextents; ++i, ++ep) {
                fno = logbtofrag(fs, ep->pbno);
                nfno = dbtofsb(fs, ep->nbno);
                for (j = 0; j < nfno; j += fs->fs_frag, fno += fs->fs_frag)
                        free(ip, fno, fs->fs_bsize, 0);
        }
        free(ip, logbtofrag(fs, logbno), fs->fs_bsize, 0);
        brelse(bp);
        bp = NULL;

        /*
         * Push the metadata dirtied during the allocations
         */
        ufsvfsp->vfs_ulockfs.ul_sbowner = curthread;
        sbupdate(ufsvfsp->vfs_vfs);
        ufsvfsp->vfs_ulockfs.ul_sbowner = (kthread_id_t)-1;
        bflush(ufsvfsp->vfs_dev);
        error = bfinval(ufsvfsp->vfs_dev, 0);
        if (error)
                goto errout;

        /*
         * Free the dummy inode
         */
        ufs_free_inode(ip);

        return (0);

errout:
        /*
         * Free up all resources
         */
        if (bp)
                brelse(bp);
        if (ip)
                ufs_free_inode(ip);
        return (error);
}

/*
 * Allocate log space
 *      Assumes the file system is write locked and is not logging
 */
static int
lufs_alloc(struct ufsvfs *ufsvfsp, struct fiolog *flp, size_t minb, cred_t *cr)
{
        int             error = 0;
        buf_t           *bp = NULL;
        extent_t        *ep, *nep;
        extent_block_t  *ebp;
        struct fs       *fs = ufsvfsp->vfs_fs;
        daddr_t         fno;    /* in frags */
        daddr_t         bno;    /* in disk blocks */
        int32_t         logbno = INT32_C(0);    /* will be fs_logbno */
        struct inode    *ip = NULL;
        size_t          nb = flp->nbytes_actual;
        size_t          tb = 0;

        /*
         * Mark the file system as FSACTIVE
         */
        ufsvfsp->vfs_ulockfs.ul_sbowner = curthread;
        mutex_enter(&ufsvfsp->vfs_lock);
        fs->fs_clean = FSACTIVE;
        ufs_sbwrite(ufsvfsp);
        mutex_exit(&ufsvfsp->vfs_lock);
        ufsvfsp->vfs_ulockfs.ul_sbowner = (kthread_id_t)-1;

        /*
         * Allocate the allocation block (need dummy shadow inode;
         * we use a shadow inode so the quota sub-system ignores
         * the block allocations.)
         *      superblock -> one block of extents -> log data
         */
        ip = ufs_alloc_inode(ufsvfsp, UFSROOTINO);
        ip->i_mode = IFSHAD;            /* make the dummy a shadow inode */
        rw_enter(&ip->i_contents, RW_WRITER);
        fno = contigpref(ufsvfsp, nb + fs->fs_bsize, minb);
        error = alloc(ip, fno, fs->fs_bsize, &fno, cr);
        if (error)
                goto errout;
        bno = fsbtodb(fs, fno);

        bp = UFS_BREAD(ufsvfsp, ufsvfsp->vfs_dev, bno, fs->fs_bsize);
        if (bp->b_flags & B_ERROR) {
                error = EIO;
                goto errout;
        }

        ebp = (void *)bp->b_un.b_addr;
        ebp->type = LUFS_EXTENTS;
        ebp->nextbno = UINT32_C(0);
        ebp->nextents = UINT32_C(0);
        ebp->chksum = INT32_C(0);
        if (fs->fs_magic == FS_MAGIC)
                logbno = bno;
        else
                logbno = dbtofsb(fs, bno);

        /*
         * Initialize the first extent
         */
        ep = &ebp->extents[0];
        error = alloc(ip, fno + fs->fs_frag, fs->fs_bsize, &fno, cr);
        if (error)
                goto errout;
        bno = fsbtodb(fs, fno);

        ep->lbno = UINT32_C(0);
        if (fs->fs_magic == FS_MAGIC)
                ep->pbno = (uint32_t)bno;
        else
                ep->pbno = (uint32_t)fno;
        ep->nbno = (uint32_t)fsbtodb(fs, fs->fs_frag);
        ebp->nextents = UINT32_C(1);
        tb = fs->fs_bsize;
        nb -= fs->fs_bsize;

        while (nb) {
                error = alloc(ip, fno + fs->fs_frag, fs->fs_bsize, &fno, cr);
                if (error) {
                        if (tb < minb)
                                goto errout;
                        error = 0;
                        break;
                }
                bno = fsbtodb(fs, fno);
                if ((daddr_t)((logbtodb(fs, ep->pbno) + ep->nbno) == bno))
                        ep->nbno += (uint32_t)(fsbtodb(fs, fs->fs_frag));
                else {
                        nep = ep + 1;
                        if ((caddr_t)(nep + 1) >
                            (bp->b_un.b_addr + fs->fs_bsize)) {
                                free(ip, fno, fs->fs_bsize, 0);
                                break;
                        }
                        nep->lbno = ep->lbno + ep->nbno;
                        if (fs->fs_magic == FS_MAGIC)
                                nep->pbno = (uint32_t)bno;
                        else
                                nep->pbno = (uint32_t)fno;
                        nep->nbno = (uint32_t)(fsbtodb(fs, fs->fs_frag));
                        ebp->nextents++;
                        ep = nep;
                }
                tb += fs->fs_bsize;
                nb -= fs->fs_bsize;
        }

        if (tb < minb) {        /* Failed to reach minimum log size */
                error = ENOSPC;
                goto errout;
        }

        ebp->nbytes = (uint32_t)tb;
        setsum(&ebp->chksum, (int32_t *)bp->b_un.b_addr, fs->fs_bsize);
        UFS_BWRITE2(ufsvfsp, bp);
        if (bp->b_flags & B_ERROR) {
                error = EIO;
                goto errout;
        }
        /*
         * Initialize the first two sectors of the log
         */
        error = lufs_initialize(ufsvfsp, logbtodb(fs, ebp->extents[0].pbno),
            tb, flp);
        if (error)
                goto errout;

        /*
         * We are done initializing the allocation block and the log
         */
        brelse(bp);
        bp = NULL;

        /*
         * Update the superblock and push the dirty metadata
         */
        ufsvfsp->vfs_ulockfs.ul_sbowner = curthread;
        sbupdate(ufsvfsp->vfs_vfs);
        ufsvfsp->vfs_ulockfs.ul_sbowner = (kthread_id_t)-1;
        bflush(ufsvfsp->vfs_dev);
        error = bfinval(ufsvfsp->vfs_dev, 1);
        if (error)
                goto errout;
        if (ufsvfsp->vfs_bufp->b_flags & B_ERROR) {
                error = EIO;
                goto errout;
        }

        /*
         * Everything is safely on disk; update log space pointer in sb
         */
        ufsvfsp->vfs_ulockfs.ul_sbowner = curthread;
        mutex_enter(&ufsvfsp->vfs_lock);
        fs->fs_logbno = (uint32_t)logbno;
        ufs_sbwrite(ufsvfsp);
        mutex_exit(&ufsvfsp->vfs_lock);
        ufsvfsp->vfs_ulockfs.ul_sbowner = (kthread_id_t)-1;

        /*
         * Free the dummy inode
         */
        rw_exit(&ip->i_contents);
        ufs_free_inode(ip);

        /* inform user of real log size */
        flp->nbytes_actual = tb;
        return (0);

errout:
        /*
         * Free all resources
         */
        if (bp)
                brelse(bp);
        if (logbno) {
                fs->fs_logbno = logbno;
                (void) lufs_free(ufsvfsp);
        }
        if (ip) {
                rw_exit(&ip->i_contents);
                ufs_free_inode(ip);
        }
        return (error);
}

/*
 * Disable logging
 */
int
lufs_disable(vnode_t *vp, struct fiolog *flp)
{
        int             error = 0;
        inode_t         *ip = VTOI(vp);
        ufsvfs_t        *ufsvfsp = ip->i_ufsvfs;
        struct fs       *fs = ufsvfsp->vfs_fs;
        struct lockfs   lf;
        struct ulockfs  *ulp;

        flp->error = FIOLOG_ENONE;

        /*
         * Logging is already disabled; done
         */
        if (fs->fs_logbno == 0 || ufsvfsp->vfs_log == NULL)
                return (0);

        /*
         * Readonly file system
         */
        if (fs->fs_ronly) {
                flp->error = FIOLOG_EROFS;
                return (0);
        }

        /*
         * File system must be write locked to disable logging
         */
        error = ufs_fiolfss(vp, &lf);
        if (error) {
                return (error);
        }
        if (!LOCKFS_IS_ULOCK(&lf)) {
                flp->error = FIOLOG_EULOCK;
                return (0);
        }
        lf.lf_lock = LOCKFS_WLOCK;
        lf.lf_flags = 0;
        lf.lf_comment = NULL;
        error = ufs_fiolfs(vp, &lf, 1);
        if (error) {
                flp->error = FIOLOG_EWLOCK;
                return (0);
        }

        if (ufsvfsp->vfs_log == NULL || fs->fs_logbno == 0)
                goto errout;

        /*
         * WE ARE COMMITTED TO DISABLING LOGGING PAST THIS POINT
         */

        /*
         * Disable logging:
         * Suspend the reclaim thread and force the delete thread to exit.
         *      When a nologging mount has completed there may still be
         *      work for reclaim to do so just suspend this thread until
         *      it's [deadlock-] safe for it to continue.  The delete
         *      thread won't be needed as ufs_iinactive() calls
         *      ufs_delete() when logging is disabled.
         * Freeze and drain reader ops.
         *      Commit any outstanding reader transactions (ufs_flush).
         *      Set the ``unmounted'' bit in the ufstrans struct.
         *      If debug, remove metadata from matamap.
         *      Disable matamap processing.
         *      NULL the trans ops table.
         *      Free all of the incore structs related to logging.
         * Allow reader ops.
         */
        ufs_thread_suspend(&ufsvfsp->vfs_reclaim);
        ufs_thread_exit(&ufsvfsp->vfs_delete);

        vfs_lock_wait(ufsvfsp->vfs_vfs);
        ulp = &ufsvfsp->vfs_ulockfs;
        mutex_enter(&ulp->ul_lock);
        atomic_inc_ulong(&ufs_quiesce_pend);
        (void) ufs_quiesce(ulp);

        (void) ufs_flush(ufsvfsp->vfs_vfs);

        TRANS_MATA_UMOUNT(ufsvfsp);
        ufsvfsp->vfs_domatamap = 0;

        /*
         * Free all of the incore structs
         * Aquire the ufs_scan_lock before de-linking the mtm data
         * structure so that we keep ufs_sync() and ufs_update() away
         * when they execute the ufs_scan_inodes() run while we're in
         * progress of enabling/disabling logging.
         */
        mutex_enter(&ufs_scan_lock);
        (void) lufs_unsnarf(ufsvfsp);
        mutex_exit(&ufs_scan_lock);

        atomic_dec_ulong(&ufs_quiesce_pend);
        mutex_exit(&ulp->ul_lock);
        vfs_setmntopt(ufsvfsp->vfs_vfs, MNTOPT_NOLOGGING, NULL, 0);
        vfs_unlock(ufsvfsp->vfs_vfs);

        fs->fs_rolled = FS_ALL_ROLLED;
        ufsvfsp->vfs_nolog_si = 0;

        /*
         * Free the log space and mark the superblock as FSACTIVE
         */
        (void) lufs_free(ufsvfsp);

        /*
         * Allow the reclaim thread to continue.
         */
        ufs_thread_continue(&ufsvfsp->vfs_reclaim);

        /*
         * Unlock the file system
         */
        lf.lf_lock = LOCKFS_ULOCK;
        lf.lf_flags = 0;
        error = ufs_fiolfs(vp, &lf, 1);
        if (error)
                flp->error = FIOLOG_ENOULOCK;

        return (0);

errout:
        lf.lf_lock = LOCKFS_ULOCK;
        lf.lf_flags = 0;
        (void) ufs_fiolfs(vp, &lf, 1);
        return (error);
}

/*
 * Enable logging
 */
int
lufs_enable(struct vnode *vp, struct fiolog *flp, cred_t *cr)
{
        int             error;
        int             reclaim;
        inode_t         *ip = VTOI(vp);
        ufsvfs_t        *ufsvfsp = ip->i_ufsvfs;
        struct fs       *fs;
        ml_unit_t       *ul;
        struct lockfs   lf;
        struct ulockfs  *ulp;
        vfs_t           *vfsp = ufsvfsp->vfs_vfs;
        uint64_t        tmp_nbytes_actual;
        uint64_t        cg_minlogsize;
        uint32_t        cgsize;
        static int      minlogsizewarn = 0;
        static int      maxlogsizewarn = 0;

        /*
         * Check if logging is already enabled
         */
        if (ufsvfsp->vfs_log) {
                flp->error = FIOLOG_ETRANS;
                /* for root ensure logging option is set */
                vfs_setmntopt(vfsp, MNTOPT_LOGGING, NULL, 0);
                return (0);
        }
        fs = ufsvfsp->vfs_fs;

        /*
         * Come back here to recheck if we had to disable the log.
         */
recheck:
        error = 0;
        reclaim = 0;
        flp->error = FIOLOG_ENONE;

        /*
         * The size of the ufs log is determined using the following rules:
         *
         * 1) If no size is requested the log size is calculated as a
         *    ratio of the total file system size. By default this is
         *    1MB of log per 1GB of file system. This calculation is then
         *    capped at the log size specified by ldl_softlogcap.
         * 2) The log size requested may then be increased based on the
         *    number of cylinder groups contained in the file system.
         *    To prevent a hang the log has to be large enough to contain a
         *    single transaction that alters every cylinder group in the file
         *    system. This is calculated as cg_minlogsize.
         * 3) Finally a check is made that the log size requested is within
         *    the limits of ldl_minlogsize and ldl_maxlogsize.
         */

        /*
         * Adjust requested log size
         */
        flp->nbytes_actual = flp->nbytes_requested;
        if (flp->nbytes_actual == 0) {
                tmp_nbytes_actual =
                    (((uint64_t)fs->fs_size) / ldl_divisor) << fs->fs_fshift;
                flp->nbytes_actual = (uint_t)MIN(tmp_nbytes_actual, INT_MAX);
                /*
                 * The 1MB per 1GB log size allocation only applies up to
                 * ldl_softlogcap size of log.
                 */
                flp->nbytes_actual = MIN(flp->nbytes_actual, ldl_softlogcap);
        }

        cgsize = ldl_cgsizereq ? ldl_cgsizereq : LDL_CGSIZEREQ(fs);

        /*
         * Determine the log size required based on the number of cylinder
         * groups in the file system. The log has to be at least this size
         * to prevent possible hangs due to log space exhaustion.
         */
        cg_minlogsize = cgsize * fs->fs_ncg;

        /*
         * Ensure that the minimum log size isn't so small that it could lead
         * to a full log hang.
         */
        if (ldl_minlogsize < LDL_MINLOGSIZE) {
                ldl_minlogsize = LDL_MINLOGSIZE;
                if (!minlogsizewarn) {
                        cmn_err(CE_WARN, "ldl_minlogsize too small, increasing "
                            "to 0x%x", LDL_MINLOGSIZE);
                        minlogsizewarn = 1;
                }
        }

        /*
         * Ensure that the maximum log size isn't greater than INT_MAX as the
         * logical log offset fields would overflow.
         */
        if (ldl_maxlogsize > INT_MAX) {
                ldl_maxlogsize = INT_MAX;
                if (!maxlogsizewarn) {
                        cmn_err(CE_WARN, "ldl_maxlogsize too large, reducing "
                            "to 0x%x", INT_MAX);
                        maxlogsizewarn = 1;
                }
        }

        if (cg_minlogsize > ldl_maxlogsize) {
                cmn_err(CE_WARN,
                    "%s: reducing calculated log size from 0x%x to "
                    "ldl_maxlogsize (0x%x).", fs->fs_fsmnt, (int)cg_minlogsize,
                    ldl_maxlogsize);
        }

        cg_minlogsize = MAX(cg_minlogsize, ldl_minlogsize);
        cg_minlogsize = MIN(cg_minlogsize, ldl_maxlogsize);

        flp->nbytes_actual = MAX(flp->nbytes_actual, cg_minlogsize);
        flp->nbytes_actual = MAX(flp->nbytes_actual, ldl_minlogsize);
        flp->nbytes_actual = MIN(flp->nbytes_actual, ldl_maxlogsize);
        flp->nbytes_actual = blkroundup(fs, flp->nbytes_actual);

        /*
         * logging is enabled and the log is the right size; done
         */
        ul = ufsvfsp->vfs_log;
        if (ul && fs->fs_logbno && (flp->nbytes_actual == ul->un_requestsize))
                        return (0);

        /*
         * Readonly file system
         */
        if (fs->fs_ronly) {
                flp->error = FIOLOG_EROFS;
                return (0);
        }

        /*
         * File system must be write locked to enable logging
         */
        error = ufs_fiolfss(vp, &lf);
        if (error) {
                return (error);
        }
        if (!LOCKFS_IS_ULOCK(&lf)) {
                flp->error = FIOLOG_EULOCK;
                return (0);
        }
        lf.lf_lock = LOCKFS_WLOCK;
        lf.lf_flags = 0;
        lf.lf_comment = NULL;
        error = ufs_fiolfs(vp, &lf, 1);
        if (error) {
                flp->error = FIOLOG_EWLOCK;
                return (0);
        }

        /*
         * Grab appropriate locks to synchronize with the rest
         * of the system
         */
        vfs_lock_wait(vfsp);
        ulp = &ufsvfsp->vfs_ulockfs;
        mutex_enter(&ulp->ul_lock);

        /*
         * File system must be fairly consistent to enable logging
         */
        if (fs->fs_clean != FSLOG &&
            fs->fs_clean != FSACTIVE &&
            fs->fs_clean != FSSTABLE &&
            fs->fs_clean != FSCLEAN) {
                flp->error = FIOLOG_ECLEAN;
                goto unlockout;
        }

        /*
         * A write-locked file system is only active if there are
         * open deleted files; so remember to set FS_RECLAIM later.
         */
        if (fs->fs_clean == FSACTIVE)
                reclaim = FS_RECLAIM;

        /*
         * Logging is already enabled; must be changing the log's size
         */
        if (fs->fs_logbno && ufsvfsp->vfs_log) {
                /*
                 * Before we can disable logging, we must give up our
                 * lock.  As a consequence of unlocking and disabling the
                 * log, the fs structure may change.  Because of this, when
                 * disabling is complete, we will go back to recheck to
                 * repeat all of the checks that we performed to get to
                 * this point.  Disabling sets fs->fs_logbno to 0, so this
                 * will not put us into an infinite loop.
                 */
                mutex_exit(&ulp->ul_lock);
                vfs_unlock(vfsp);

                lf.lf_lock = LOCKFS_ULOCK;
                lf.lf_flags = 0;
                error = ufs_fiolfs(vp, &lf, 1);
                if (error) {
                        flp->error = FIOLOG_ENOULOCK;
                        return (0);
                }
                error = lufs_disable(vp, flp);
                if (error || (flp->error != FIOLOG_ENONE))
                        return (0);
                goto recheck;
        }

        error = lufs_alloc(ufsvfsp, flp, cg_minlogsize, cr);
        if (error)
                goto errout;

        /*
         * Create all of the incore structs
         */
        error = lufs_snarf(ufsvfsp, fs, 0);
        if (error)
                goto errout;

        /*
         * DON'T ``GOTO ERROUT'' PAST THIS POINT
         */

        /*
         * Pretend we were just mounted with logging enabled
         *              Get the ops vector
         *              If debug, record metadata locations with log subsystem
         *              Start the delete thread
         *              Start the reclaim thread, if necessary
         */
        vfs_setmntopt(vfsp, MNTOPT_LOGGING, NULL, 0);

        TRANS_DOMATAMAP(ufsvfsp);
        TRANS_MATA_MOUNT(ufsvfsp);
        TRANS_MATA_SI(ufsvfsp, fs);
        ufs_thread_start(&ufsvfsp->vfs_delete, ufs_thread_delete, vfsp);
        if (fs->fs_reclaim & (FS_RECLAIM|FS_RECLAIMING)) {
                fs->fs_reclaim &= ~FS_RECLAIM;
                fs->fs_reclaim |=  FS_RECLAIMING;
                ufs_thread_start(&ufsvfsp->vfs_reclaim,
                    ufs_thread_reclaim, vfsp);
        } else
                fs->fs_reclaim |= reclaim;

        mutex_exit(&ulp->ul_lock);
        vfs_unlock(vfsp);

        /*
         * Unlock the file system
         */
        lf.lf_lock = LOCKFS_ULOCK;
        lf.lf_flags = 0;
        error = ufs_fiolfs(vp, &lf, 1);
        if (error) {
                flp->error = FIOLOG_ENOULOCK;
                return (0);
        }

        /*
         * There's nothing in the log yet (we've just allocated it)
         * so directly write out the super block.
         * Note, we have to force this sb out to disk
         * (not just to the log) so that if we crash we know we are logging
         */
        mutex_enter(&ufsvfsp->vfs_lock);
        fs->fs_clean = FSLOG;
        fs->fs_rolled = FS_NEED_ROLL; /* Mark the fs as unrolled */
        UFS_BWRITE2(NULL, ufsvfsp->vfs_bufp);
        mutex_exit(&ufsvfsp->vfs_lock);

        return (0);

errout:
        /*
         * Aquire the ufs_scan_lock before de-linking the mtm data
         * structure so that we keep ufs_sync() and ufs_update() away
         * when they execute the ufs_scan_inodes() run while we're in
         * progress of enabling/disabling logging.
         */
        mutex_enter(&ufs_scan_lock);
        (void) lufs_unsnarf(ufsvfsp);
        mutex_exit(&ufs_scan_lock);

        (void) lufs_free(ufsvfsp);
unlockout:
        mutex_exit(&ulp->ul_lock);
        vfs_unlock(vfsp);

        lf.lf_lock = LOCKFS_ULOCK;
        lf.lf_flags = 0;
        (void) ufs_fiolfs(vp, &lf, 1);
        return (error);
}

void
lufs_read_strategy(ml_unit_t *ul, buf_t *bp)
{
        mt_map_t        *logmap = ul->un_logmap;
        offset_t        mof     = ldbtob(bp->b_blkno);
        off_t           nb      = bp->b_bcount;
        mapentry_t      *age;
        char            *va;
        int             (*saviodone)();
        int             entire_range;

        /*
         * get a linked list of overlapping deltas
         * returns with &mtm->mtm_rwlock held
         */
        entire_range = logmap_list_get(logmap, mof, nb, &age);

        /*
         * no overlapping deltas were found; read master
         */
        if (age == NULL) {
                rw_exit(&logmap->mtm_rwlock);
                if (ul->un_flags & LDL_ERROR) {
                        bp->b_flags |= B_ERROR;
                        bp->b_error = EIO;
                        biodone(bp);
                } else {
                        ul->un_ufsvfs->vfs_iotstamp = ddi_get_lbolt();
                        logstats.ls_lreads.value.ui64++;
                        (void) bdev_strategy(bp);
                        lwp_stat_update(LWP_STAT_INBLK, 1);
                }
                return;
        }

        va = bp_mapin_common(bp, VM_SLEEP);
        /*
         * if necessary, sync read the data from master
         *      errors are returned in bp
         */
        if (!entire_range) {
                saviodone = bp->b_iodone;
                bp->b_iodone = trans_not_done;
                logstats.ls_mreads.value.ui64++;
                (void) bdev_strategy(bp);
                lwp_stat_update(LWP_STAT_INBLK, 1);
                if (trans_not_wait(bp))
                        ldl_seterror(ul, "Error reading master");
                bp->b_iodone = saviodone;
        }

        /*
         * sync read the data from the log
         *      errors are returned inline
         */
        if (ldl_read(ul, va, mof, nb, age)) {
                bp->b_flags |= B_ERROR;
                bp->b_error = EIO;
        }

        /*
         * unlist the deltas
         */
        logmap_list_put(logmap, age);

        /*
         * all done
         */
        if (ul->un_flags & LDL_ERROR) {
                bp->b_flags |= B_ERROR;
                bp->b_error = EIO;
        }
        biodone(bp);
}

void
lufs_write_strategy(ml_unit_t *ul, buf_t *bp)
{
        offset_t        mof     = ldbtob(bp->b_blkno);
        off_t           nb      = bp->b_bcount;
        char            *va;
        mapentry_t      *me;

        ASSERT((nb & DEV_BMASK) == 0);
        ul->un_logmap->mtm_ref = 1;

        /*
         * if there are deltas, move into log
         */
        me = deltamap_remove(ul->un_deltamap, mof, nb);
        if (me) {

                va = bp_mapin_common(bp, VM_SLEEP);

                ASSERT(((ul->un_debug & MT_WRITE_CHECK) == 0) ||
                    (ul->un_matamap == NULL)||
                    matamap_within(ul->un_matamap, mof, nb));

                /*
                 * move to logmap
                 */
                if (ufs_crb_enable) {
                        logmap_add_buf(ul, va, mof, me,
                            bp->b_un.b_addr, nb);
                } else {
                        logmap_add(ul, va, mof, me);
                }

                if (ul->un_flags & LDL_ERROR) {
                        bp->b_flags |= B_ERROR;
                        bp->b_error = EIO;
                }
                biodone(bp);
                return;
        }
        if (ul->un_flags & LDL_ERROR) {
                bp->b_flags |= B_ERROR;
                bp->b_error = EIO;
                biodone(bp);
                return;
        }

        /*
         * Check that we are not updating metadata, or if so then via B_PHYS.
         */
        ASSERT((ul->un_matamap == NULL) ||
            !(matamap_overlap(ul->un_matamap, mof, nb) &&
            ((bp->b_flags & B_PHYS) == 0)));

        ul->un_ufsvfs->vfs_iotstamp = ddi_get_lbolt();
        logstats.ls_lwrites.value.ui64++;

        /* If snapshots are enabled, write through the snapshot driver */
        if (ul->un_ufsvfs->vfs_snapshot)
                fssnap_strategy(&ul->un_ufsvfs->vfs_snapshot, bp);
        else
                (void) bdev_strategy(bp);

        lwp_stat_update(LWP_STAT_OUBLK, 1);
}

void
lufs_strategy(ml_unit_t *ul, buf_t *bp)
{
        if (bp->b_flags & B_READ)
                lufs_read_strategy(ul, bp);
        else
                lufs_write_strategy(ul, bp);
}

/* ARGSUSED */
static int
delta_stats_update(kstat_t *ksp, int rw)
{
        if (rw == KSTAT_WRITE) {
                delta_stats[DT_SB] = dkstats.ds_superblock_deltas.value.ui64;
                delta_stats[DT_CG] = dkstats.ds_bitmap_deltas.value.ui64;
                delta_stats[DT_SI] = dkstats.ds_suminfo_deltas.value.ui64;
                delta_stats[DT_AB] = dkstats.ds_allocblk_deltas.value.ui64;
                delta_stats[DT_ABZERO] = dkstats.ds_ab0_deltas.value.ui64;
                delta_stats[DT_DIR] = dkstats.ds_dir_deltas.value.ui64;
                delta_stats[DT_INODE] = dkstats.ds_inode_deltas.value.ui64;
                delta_stats[DT_FBI] = dkstats.ds_fbiwrite_deltas.value.ui64;
                delta_stats[DT_QR] = dkstats.ds_quota_deltas.value.ui64;
                delta_stats[DT_SHAD] = dkstats.ds_shadow_deltas.value.ui64;

                roll_stats[DT_SB] = dkstats.ds_superblock_rolled.value.ui64;
                roll_stats[DT_CG] = dkstats.ds_bitmap_rolled.value.ui64;
                roll_stats[DT_SI] = dkstats.ds_suminfo_rolled.value.ui64;
                roll_stats[DT_AB] = dkstats.ds_allocblk_rolled.value.ui64;
                roll_stats[DT_ABZERO] = dkstats.ds_ab0_rolled.value.ui64;
                roll_stats[DT_DIR] = dkstats.ds_dir_rolled.value.ui64;
                roll_stats[DT_INODE] = dkstats.ds_inode_rolled.value.ui64;
                roll_stats[DT_FBI] = dkstats.ds_fbiwrite_rolled.value.ui64;
                roll_stats[DT_QR] = dkstats.ds_quota_rolled.value.ui64;
                roll_stats[DT_SHAD] = dkstats.ds_shadow_rolled.value.ui64;
        } else {
                dkstats.ds_superblock_deltas.value.ui64 = delta_stats[DT_SB];
                dkstats.ds_bitmap_deltas.value.ui64 = delta_stats[DT_CG];
                dkstats.ds_suminfo_deltas.value.ui64 = delta_stats[DT_SI];
                dkstats.ds_allocblk_deltas.value.ui64 = delta_stats[DT_AB];
                dkstats.ds_ab0_deltas.value.ui64 = delta_stats[DT_ABZERO];
                dkstats.ds_dir_deltas.value.ui64 = delta_stats[DT_DIR];
                dkstats.ds_inode_deltas.value.ui64 = delta_stats[DT_INODE];
                dkstats.ds_fbiwrite_deltas.value.ui64 = delta_stats[DT_FBI];
                dkstats.ds_quota_deltas.value.ui64 = delta_stats[DT_QR];
                dkstats.ds_shadow_deltas.value.ui64 = delta_stats[DT_SHAD];

                dkstats.ds_superblock_rolled.value.ui64 = roll_stats[DT_SB];
                dkstats.ds_bitmap_rolled.value.ui64 = roll_stats[DT_CG];
                dkstats.ds_suminfo_rolled.value.ui64 = roll_stats[DT_SI];
                dkstats.ds_allocblk_rolled.value.ui64 = roll_stats[DT_AB];
                dkstats.ds_ab0_rolled.value.ui64 = roll_stats[DT_ABZERO];
                dkstats.ds_dir_rolled.value.ui64 = roll_stats[DT_DIR];
                dkstats.ds_inode_rolled.value.ui64 = roll_stats[DT_INODE];
                dkstats.ds_fbiwrite_rolled.value.ui64 = roll_stats[DT_FBI];
                dkstats.ds_quota_rolled.value.ui64 = roll_stats[DT_QR];
                dkstats.ds_shadow_rolled.value.ui64 = roll_stats[DT_SHAD];
        }
        return (0);
}

extern size_t ufs_crb_limit;
extern int ufs_max_crb_divisor;

void
lufs_init(void)
{
        kstat_t *ksp;

        /* Create kmem caches */
        lufs_sv = kmem_cache_create("lufs_save", sizeof (lufs_save_t), 0,
            NULL, NULL, NULL, NULL, NULL, 0);
        lufs_bp = kmem_cache_create("lufs_bufs", sizeof (lufs_buf_t), 0,
            NULL, NULL, NULL, NULL, NULL, 0);

        mutex_init(&log_mutex, NULL, MUTEX_DEFAULT, NULL);

        _init_top();

        if (bio_lufs_strategy == NULL)
                bio_lufs_strategy = (void (*) (void *, buf_t *)) lufs_strategy;

        /*
         * Initialise general logging and delta kstats
         */
        ksp = kstat_create("ufs_log", 0, "logstats", "ufs", KSTAT_TYPE_NAMED,
            sizeof (logstats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL);
        if (ksp) {
                ksp->ks_data = (void *) &logstats;
                kstat_install(ksp);
        }

        ksp = kstat_create("ufs_log", 0, "deltastats", "ufs", KSTAT_TYPE_NAMED,
            sizeof (dkstats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL);
        if (ksp) {
                ksp->ks_data = (void *) &dkstats;
                ksp->ks_update = delta_stats_update;
                kstat_install(ksp);
        }

        /* Initialize  generation of logging ids */
        lufs_genid_init();

        /*
         * Set up the maximum amount of kmem that the crbs (system wide)
         * can use.
         */
        ufs_crb_limit = kmem_maxavail() / ufs_max_crb_divisor;
}