/*
 * Copyright (c) 2013-2019 The DragonFly Project.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@dragonflybsd.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name of The DragonFly Project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific, prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <vm/vm_kern.h>
#include <vm/vm_extern.h>

#include "hammer2.h"

/*
 * breadth-first search
 */
typedef struct hammer2_chain_save {
        TAILQ_ENTRY(hammer2_chain_save) entry;
        hammer2_chain_t *chain;
} hammer2_chain_save_t;

TAILQ_HEAD(hammer2_chain_save_list, hammer2_chain_save);
typedef struct hammer2_chain_save_list hammer2_chain_save_list_t;

typedef struct hammer2_bulkfree_info {
        hammer2_dev_t           *hmp;
        kmem_anon_desc_t        kp;
        hammer2_off_t           sbase;          /* sub-loop iteration */
        hammer2_off_t           sstop;
        hammer2_bmap_data_t     *bmap;
        int                     depth;
        long                    count_10_00;    /* staged->free      */
        long                    count_11_10;    /* allocated->staged */
        long                    count_00_11;    /* (should not happen) */
        long                    count_01_11;    /* (should not happen) */
        long                    count_10_11;    /* staged->allocated */
        long                    count_l0cleans;
        long                    count_linadjusts;
        long                    count_inodes_scanned;
        long                    count_dirents_scanned;
        long                    count_dedup_factor;
        long                    count_bytes_scanned;
        long                    count_chains_scanned;
        long                    count_chains_reported;
        long                    bulkfree_calls;
        int                     bulkfree_ticks;
        int                     list_alert;
        hammer2_off_t           adj_free;
        hammer2_tid_t           mtid;
        time_t                  save_time;
        hammer2_chain_save_list_t list;
        long                    list_count;
        long                    list_count_max;
        hammer2_chain_save_t    *backout;       /* ins pt while backing out */
        hammer2_dedup_t         *dedup;
        int                     pri;
} hammer2_bulkfree_info_t;

static int h2_bulkfree_test(hammer2_bulkfree_info_t *info,
                        hammer2_blockref_t *bref, int pri, int saved_error);
static uint32_t bigmask_get(hammer2_bmap_data_t *bmap);
static int bigmask_good(hammer2_bmap_data_t *bmap, uint32_t live_bigmask);

/*
 * General bulk scan function with callback.  Called with a referenced
 * but UNLOCKED parent.  The parent is returned in the same state.
 */
static
int
hammer2_bulkfree_scan(hammer2_chain_t *parent,
                  int (*func)(hammer2_bulkfree_info_t *info,
                              hammer2_blockref_t *bref),
                  hammer2_bulkfree_info_t *info)
{
        hammer2_blockref_t bref;
        hammer2_chain_t *chain;
        hammer2_chain_save_t *tail;
        hammer2_chain_save_t *save;
        int first = 1;
        int rup_error;
        int error;
        int e2;

        ++info->pri;

        chain = NULL;
        rup_error = 0;
        error = 0;

        hammer2_chain_lock(parent, HAMMER2_RESOLVE_ALWAYS |
                                   HAMMER2_RESOLVE_SHARED);

        /*
         * End of scan if parent is a PFS
         */
        tail = TAILQ_FIRST(&info->list);

        /*
         * The parent was previously retrieved NODATA and thus has not
         * tested the CRC.  Now that we have locked it normally, check
         * for a CRC problem and skip it if we found one.  The bulk scan
         * cannot safely traverse invalid block tables (we could end up
         * in an endless loop or cause a panic).
         */
        if (parent->error & HAMMER2_ERROR_CHECK) {
                error = parent->error;
                goto done;
        }

        /*
         * Report which PFS is being scanned
         */
        if (parent->bref.type == HAMMER2_BREF_TYPE_INODE &&
            (parent->bref.flags & HAMMER2_BREF_FLAG_PFSROOT)) {
                kprintf("hammer2_bulkfree: Scanning %s\n",
                        parent->data->ipdata.filename);
        }

        /*
         * Generally loop on the contents if we have not been flagged
         * for abort.
         *
         * Remember that these chains are completely isolated from
         * the frontend, so we can release locks temporarily without
         * imploding.
         */
        for (;;) {
                error |= hammer2_chain_scan(parent, &chain, &bref, &first,
                                            HAMMER2_LOOKUP_NODATA |
                                            HAMMER2_LOOKUP_SHARED);

                /*
                 * Handle EOF or other error at current level.  This stops
                 * the bulkfree scan.
                 */
                if (error & ~HAMMER2_ERROR_CHECK)
                        break;

                /*
                 * Account for dirents before thre data_off test, since most
                 * dirents do not need a data reference.
                 */
                if (bref.type == HAMMER2_BREF_TYPE_DIRENT)
                        ++info->count_dirents_scanned;

                /*
                 * Ignore brefs without data (typically dirents)
                 */
                if ((bref.data_off & ~HAMMER2_OFF_MASK_RADIX) == 0)
                        continue;

                /*
                 * Process bref, chain is only non-NULL if the bref
                 * might be recursable (its possible that we sometimes get
                 * a non-NULL chain where the bref cannot be recursed).
                 *
                 * If we already ran down this tree we do not have to do it
                 * again, but we must still recover any cumulative error
                 * recorded from the time we did.
                 */
                ++info->pri;
                e2 = h2_bulkfree_test(info, &bref, 1, 0);
                if (e2) {
                        error |= e2 & ~HAMMER2_ERROR_EOF;
                        continue;
                }

                if (bref.type == HAMMER2_BREF_TYPE_INODE)
                        ++info->count_inodes_scanned;

                error |= func(info, &bref);
                if (error & ~HAMMER2_ERROR_CHECK)
                        break;

                /*
                 * A non-null chain is always returned if it is
                 * recursive, otherwise a non-null chain might be
                 * returned but usually is not when not recursive.
                 */
                if (chain == NULL)
                        continue;

                info->count_bytes_scanned += chain->bytes;
                ++info->count_chains_scanned;

                if (info->count_chains_scanned >=
                    info->count_chains_reported + 1000000 ||
                    (info->count_chains_scanned < 1000000 &&
                     info->count_chains_scanned >=
                     info->count_chains_reported + 100000)) {
                        kprintf(" chains %-7ld inodes %-7ld "
                                "dirents %-7ld bytes %5ldMB\n",
                                info->count_chains_scanned,
                                info->count_inodes_scanned,
                                info->count_dirents_scanned,
                                info->count_bytes_scanned / 1000000);
                        info->count_chains_reported =
                                info->count_chains_scanned;
                }

                /*
                 * Else check type and setup depth-first scan.
                 *
                 * Account for bytes actually read.
                 */
                switch(chain->bref.type) {
                case HAMMER2_BREF_TYPE_INODE:
                case HAMMER2_BREF_TYPE_FREEMAP_NODE:
                case HAMMER2_BREF_TYPE_INDIRECT:
                case HAMMER2_BREF_TYPE_VOLUME:
                case HAMMER2_BREF_TYPE_FREEMAP:
                        ++info->depth;
                        if (chain->error & HAMMER2_ERROR_CHECK) {
                                /*
                                 * Cannot safely recurse chains with crc
                                 * errors, even in emergency mode.
                                 */
                                /* NOP */
                        } else if (info->depth > 16 ||
                                   info->backout ||
                                   (info->depth > hammer2_limit_saved_depth &&
                                   info->list_count >=
                                    (hammer2_limit_saved_chains >> 2)))
                        {
                                /*
                                 * We must defer the recursion if it runs
                                 * too deep or if too many saved chains are
                                 * allocated.
                                 *
                                 * In the case of too many saved chains, we
                                 * have to stop recursing ASAP to avoid an
                                 * explosion of memory use since each radix
                                 * level can hold 512 elements.
                                 *
                                 * If we had to defer at a deeper level
                                 * backout is non-NULL.  We must backout
                                 * completely before resuming.
                                 */
                                if (info->list_count >
                                     hammer2_limit_saved_chains &&
                                    info->list_alert == 0)
                                {
                                        kprintf("hammer2: during bulkfree, "
                                                "saved chains exceeded %ld "
                                                "at depth %d, "
                                                "backing off to less-efficient "
                                                "operation\n",
                                                hammer2_limit_saved_chains,
                                                info->depth);
                                        info->list_alert = 1;
                                }

                                /*
                                 * Must be placed at head so pfsroot scan
                                 * can exhaust saved elements for that pfs
                                 * first.
                                 *
                                 * Must be placed at head for depth-first
                                 * recovery when too many saved chains, to
                                 * limit number of chains saved during
                                 * saved-chain reruns.  The worst-case excess
                                 * is (maximum_depth * 512) saved chains above
                                 * the threshold.
                                 *
                                 * The maximum_depth generally occurs in the
                                 * inode index and can be fairly deep once
                                 * the radix tree becomes a bit fragmented.
                                 * nominally 100M inodes would be only 4 deep,
                                 * plus a maximally sized file would be another
                                 * 8 deep, but with fragmentation it can wind
                                 * up being a lot more.
                                 *
                                 * However, when backing out, we have to place
                                 * all the entries in each parent node not
                                 * yet processed on the list too, and because
                                 * these entries are shallower they must be
                                 * placed after each other in order to maintain
                                 * our depth-first processing.
                                 */
                                save = kmalloc(sizeof(*save), M_HAMMER2,
                                               M_WAITOK | M_ZERO);
                                save->chain = chain;
                                hammer2_chain_ref(chain);

                                if (info->backout) {
                                        TAILQ_INSERT_AFTER(&info->list,
                                                           info->backout,
                                                           save, entry);
                                } else {
                                        TAILQ_INSERT_HEAD(&info->list,
                                                          save, entry);
                                }
                                info->backout = save;
                                ++info->list_count;
                                if (info->list_count_max < info->list_count)
                                        info->list_count_max = info->list_count;

                                /* guess */
                                info->pri += 10;
                        } else {
                                int savepri = info->pri;

                                hammer2_chain_unlock(chain);
                                hammer2_chain_unlock(parent);
                                info->pri = 0;
                                rup_error |= hammer2_bulkfree_scan(chain,
                                                                   func, info);
                                info->pri += savepri;
                                hammer2_chain_lock(parent,
                                                   HAMMER2_RESOLVE_ALWAYS |
                                                   HAMMER2_RESOLVE_SHARED);
                                hammer2_chain_lock(chain,
                                                   HAMMER2_RESOLVE_ALWAYS |
                                                   HAMMER2_RESOLVE_SHARED);
                        }
                        --info->depth;
                        break;
                case HAMMER2_BREF_TYPE_DATA:
                        break;
                default:
                        /* does not recurse */
                        break;
                }
                if (rup_error & HAMMER2_ERROR_ABORTED)
                        break;
        }
        if (chain) {
                hammer2_chain_unlock(chain);
                hammer2_chain_drop(chain);
        }

        /*
         * If this is a PFSROOT, also re-run any defered elements
         * added during our scan so we can report any cumulative errors
         * for the PFS.
         */
        if (parent->bref.type == HAMMER2_BREF_TYPE_INODE &&
            (parent->bref.flags & HAMMER2_BREF_FLAG_PFSROOT)) {
                for (;;) {
                        int opri;

                        save = TAILQ_FIRST(&info->list);
                        if (save == tail)       /* exhaust this PFS only */
                                break;

                        TAILQ_REMOVE(&info->list, save, entry);
                        info->backout = NULL;
                        --info->list_count;
                        opri = info->pri;
                        info->pri = 0;
                        rup_error |= hammer2_bulkfree_scan(save->chain, func, info);
                        hammer2_chain_drop(save->chain);
                        kfree(save, M_HAMMER2);
                        info->pri = opri;
                }
        }

        error |= rup_error;

        /*
         * Report which PFS the errors were encountered in.
         */
        if (parent->bref.type == HAMMER2_BREF_TYPE_INODE &&
            (parent->bref.flags & HAMMER2_BREF_FLAG_PFSROOT) &&
            (error & ~HAMMER2_ERROR_EOF)) {
                kprintf("hammer2_bulkfree: Encountered errors (%08x) "
                        "while scanning \"%s\"\n",
                        error, parent->data->ipdata.filename);
        }

        /*
         * Save with higher pri now that we know what it is.
         */
        h2_bulkfree_test(info, &parent->bref, info->pri + 1,
                         (error & ~HAMMER2_ERROR_EOF));

done:
        hammer2_chain_unlock(parent);

        return (error & ~HAMMER2_ERROR_EOF);
}

/*
 * Bulkfree algorithm
 *
 * Repeat {
 *      Chain flush (partial synchronization) XXX removed
 *      Scan the whole topology - build in-memory freemap (mark 11)
 *      Reconcile the in-memory freemap against the on-disk freemap.
 *              ondisk xx -> ondisk 11 (if allocated)
 *              ondisk 11 -> ondisk 10 (if free in-memory)
 *              ondisk 10 -> ondisk 00 (if free in-memory) - on next pass
 * }
 *
 * The topology scan may have to be performed multiple times to window
 * freemaps which are too large to fit in kernel memory.
 *
 * Races are handled using a double-transition (11->10, 10->00).  The bulkfree
 * scan snapshots the volume root's blockset and thus can run concurrent with
 * normal operations, as long as a full flush is made between each pass to
 * synchronize any modified chains (otherwise their blocks might be improperly
 * freed).
 *
 * Temporary memory in multiples of 32KB is required to reconstruct the leaf
 * hammer2_bmap_data blocks so they can later be compared against the live
 * freemap.  Each 32KB represents 256 x 16KB x 256 = ~1 GB of storage.
 * A 32MB save area thus represents around ~1 TB.  The temporary memory
 * allocated can be specified.  If it is not sufficient multiple topology
 * passes will be made.
 */

/*
 * Bulkfree callback info
 */
static void hammer2_bulkfree_thread(void *arg __unused);
static void cbinfo_bmap_init(hammer2_bulkfree_info_t *cbinfo, size_t size);
static int h2_bulkfree_callback(hammer2_bulkfree_info_t *cbinfo,
                        hammer2_blockref_t *bref);
static int h2_bulkfree_sync(hammer2_bulkfree_info_t *cbinfo);
static void h2_bulkfree_sync_adjust(hammer2_bulkfree_info_t *cbinfo,
                        hammer2_off_t data_off, hammer2_bmap_data_t *live,
                        hammer2_bmap_data_t *bmap, hammer2_key_t alloc_base);

void
hammer2_bulkfree_init(hammer2_dev_t *hmp)
{
        hammer2_thr_create(&hmp->bfthr, NULL, hmp,
                           hmp->devrepname, -1, -1,
                           hammer2_bulkfree_thread);
}

void
hammer2_bulkfree_uninit(hammer2_dev_t *hmp)
{
        hammer2_thr_delete(&hmp->bfthr);
}

static void
hammer2_bulkfree_thread(void *arg)
{
        hammer2_thread_t *thr = arg;
        hammer2_ioc_bulkfree_t bfi;
        uint32_t flags;

        for (;;) {
                hammer2_thr_wait_any(thr,
                                     HAMMER2_THREAD_STOP |
                                     HAMMER2_THREAD_FREEZE |
                                     HAMMER2_THREAD_UNFREEZE |
                                     HAMMER2_THREAD_REMASTER,
                                     hz * 60);

                flags = thr->flags;
                cpu_ccfence();
                if (flags & HAMMER2_THREAD_STOP)
                        break;
                if (flags & HAMMER2_THREAD_FREEZE) {
                        hammer2_thr_signal2(thr, HAMMER2_THREAD_FROZEN,
                                                 HAMMER2_THREAD_FREEZE);
                        continue;
                }
                if (flags & HAMMER2_THREAD_UNFREEZE) {
                        hammer2_thr_signal2(thr, 0,
                                                 HAMMER2_THREAD_FROZEN |
                                                 HAMMER2_THREAD_UNFREEZE);
                        continue;
                }
                if (flags & HAMMER2_THREAD_FROZEN)
                        continue;
                if (flags & HAMMER2_THREAD_REMASTER) {
                        hammer2_thr_signal2(thr, 0, HAMMER2_THREAD_REMASTER);
                        bzero(&bfi, sizeof(bfi));
                        bfi.size = 8192 * 1024;
                        /* hammer2_bulkfree_pass(thr->hmp, &bfi); */
                }
        }
        thr->td = NULL;
        hammer2_thr_signal(thr, HAMMER2_THREAD_STOPPED);
        /* structure can go invalid at this point */
}

int
hammer2_bulkfree_pass(hammer2_dev_t *hmp, hammer2_chain_t *vchain,
                      hammer2_ioc_bulkfree_t *bfi)
{
        hammer2_bulkfree_info_t cbinfo;
        hammer2_chain_save_t *save;
        hammer2_off_t incr;
        size_t size;
        int error;

        /*
         * We have to clear the live dedup cache as it might have entries
         * that are freeable as of now.  Any new entries in the dedup cache
         * made after this point, even if they become freeable, will have
         * previously been fully allocated and will be protected by the
         * 2-stage bulkfree.
         */
        hammer2_dedup_clear(hmp);

        /*
         * Setup for free pass using the buffer size specified by the
         * hammer2 utility, 32K-aligned.
         */
        bzero(&cbinfo, sizeof(cbinfo));
        size = (bfi->size + HAMMER2_FREEMAP_LEVELN_PSIZE - 1) &
               ~(size_t)(HAMMER2_FREEMAP_LEVELN_PSIZE - 1);

        /*
         * Cap at 1/4 physical memory (hammer2 utility will not normally
         * ever specify a buffer this big, but leave the option available).
         */
        if (size > kmem_lim_size() * 1024 * 1024 / 4) {
                size = kmem_lim_size() * 1024 * 1024 / 4;
                kprintf("hammer2: Warning: capping bulkfree buffer at %jdM\n",
                        (intmax_t)size / (1024 * 1024));
        }

#define HAMMER2_FREEMAP_SIZEDIV \
        (HAMMER2_FREEMAP_LEVEL1_SIZE / HAMMER2_FREEMAP_LEVELN_PSIZE)

        /*
         * Cap at the size needed to cover the whole volume to avoid
         * making an unnecessarily large allocation.
         */
        if (size > hmp->total_size / HAMMER2_FREEMAP_SIZEDIV)
                size = howmany(hmp->total_size, HAMMER2_FREEMAP_SIZEDIV);

        /*
         * Minimum bitmap buffer size, then align to a LEVELN_PSIZE (32K)
         * boundary.
         */
        if (size < 1024 * 1024)
                size = 1024 * 1024;
        size = (size + HAMMER2_FREEMAP_LEVELN_PSIZE - 1) &
               ~(size_t)(HAMMER2_FREEMAP_LEVELN_PSIZE - 1);

        cbinfo.hmp = hmp;
        cbinfo.bmap = kmem_alloc_swapbacked(&cbinfo.kp, size, VM_SUBSYS_HAMMER);
        cbinfo.dedup = kmalloc(sizeof(*cbinfo.dedup) * HAMMER2_DEDUP_HEUR_SIZE,
                               M_HAMMER2, M_WAITOK | M_ZERO);

        kprintf("hammer2: bulkfree buf=%jdM\n",
                (intmax_t)size / (1024 * 1024));

        /*
         * Normalize start point to a 1GB boundary.  We operate on a
         * 32KB leaf bitmap boundary which represents 1GB of storage.
         */
        cbinfo.sbase = bfi->sbase;
        if (cbinfo.sbase > hmp->total_size)
                cbinfo.sbase = hmp->total_size;
        cbinfo.sbase &= ~HAMMER2_FREEMAP_LEVEL1_MASK;
        TAILQ_INIT(&cbinfo.list);

        cbinfo.bulkfree_ticks = ticks;

        /*
         * Loop on a full meta-data scan as many times as required to
         * get through all available storage.
         */
        error = 0;
        while (cbinfo.sbase < hmp->total_size) {
                /*
                 * We have enough ram to represent (incr) bytes of storage.
                 * Each 32KB of ram represents 1GB of storage.
                 *
                 * We must also clean out our de-duplication heuristic for
                 * each (incr) bytes of storage, otherwise we wind up not
                 * scanning meta-data for later areas of storage because
                 * they had already been scanned in earlier areas of storage.
                 * Since the ranging is different, we have to restart
                 * the dedup heuristic too.
                 */
                int allmedia;

                cbinfo_bmap_init(&cbinfo, size);
                bzero(cbinfo.dedup, sizeof(*cbinfo.dedup) *
                                    HAMMER2_DEDUP_HEUR_SIZE);
                cbinfo.count_inodes_scanned = 0;
                cbinfo.count_dirents_scanned = 0;
                cbinfo.count_bytes_scanned = 0;
                cbinfo.count_chains_scanned = 0;
                cbinfo.count_chains_reported = 0;

                incr = size / HAMMER2_FREEMAP_LEVELN_PSIZE *
                       HAMMER2_FREEMAP_LEVEL1_SIZE;
                if (hmp->total_size - cbinfo.sbase <= incr) {
                        cbinfo.sstop = hmp->total_size;
                        allmedia = 1;
                } else {
                        cbinfo.sstop = cbinfo.sbase + incr;
                        allmedia = 0;
                }
                kprintf("hammer2: pass %016jx-%016jx ",
                        (intmax_t)cbinfo.sbase,
                        (intmax_t)cbinfo.sstop);
                if (allmedia && cbinfo.sbase == 0)
                        kprintf("(all media)\n");
                else if (allmedia)
                        kprintf("(remaining media)\n");
                else
                        kprintf("(%jdGB of media)\n",
                                (intmax_t)incr / (1024L*1024*1024));

                /*
                 * Scan topology for stuff inside this range.
                 *
                 * NOTE - By not using a transaction the operation can
                 *        run concurrent with the frontend as well as
                 *        with flushes.
                 *
                 *        We cannot safely set a mtid without a transaction,
                 *        and in fact we don't want to set one anyway.  We
                 *        want the bulkfree to be passive and no interfere
                 *        with crash recovery.
                 */
#undef HAMMER2_BULKFREE_TRANS   /* undef - don't use transaction */
#ifdef HAMMER2_BULKFREE_TRANS
                hammer2_trans_init(hmp->spmp, 0);
                cbinfo.mtid = hammer2_trans_sub(hmp->spmp);
#else
                cbinfo.mtid = 0;
#endif
                cbinfo.pri = 0;
                error |= hammer2_bulkfree_scan(vchain,
                                               h2_bulkfree_callback, &cbinfo);

                while ((save = TAILQ_FIRST(&cbinfo.list)) != NULL &&
                       (error & ~HAMMER2_ERROR_CHECK) == 0) {
                        TAILQ_REMOVE(&cbinfo.list, save, entry);
                        --cbinfo.list_count;
                        cbinfo.pri = 0;
                        cbinfo.backout = NULL;
                        error |= hammer2_bulkfree_scan(save->chain,
                                                       h2_bulkfree_callback,
                                                       &cbinfo);
                        hammer2_chain_drop(save->chain);
                        kfree(save, M_HAMMER2);
                }
                while (save) {
                        TAILQ_REMOVE(&cbinfo.list, save, entry);
                        --cbinfo.list_count;
                        hammer2_chain_drop(save->chain);
                        kfree(save, M_HAMMER2);
                        save = TAILQ_FIRST(&cbinfo.list);
                }
                cbinfo.backout = NULL;

                /*
                 * If the complete scan succeeded we can synchronize our
                 * in-memory freemap against live storage.  If an abort
                 * occured we cannot safely synchronize our partially
                 * filled-out in-memory freemap.
                 *
                 * We still synchronize on CHECK failures.  That is, we still
                 * want bulkfree to operate even if the filesystem has defects.
                 */
                if (error & ~HAMMER2_ERROR_CHECK) {
                        kprintf("bulkfree lastdrop %d %d error=0x%04x\n",
                                vchain->refs, vchain->core.chain_count, error);
                } else {
                        if (error & HAMMER2_ERROR_CHECK) {
                                kprintf("bulkfree lastdrop %d %d "
                                        "(with check errors)\n",
                                        vchain->refs, vchain->core.chain_count);
                        } else {
                                kprintf("bulkfree lastdrop %d %d\n",
                                        vchain->refs, vchain->core.chain_count);
                        }

                        error = h2_bulkfree_sync(&cbinfo);

                        hammer2_voldata_lock(hmp);
                        hammer2_voldata_modify(hmp);
                        hmp->voldata.allocator_free += cbinfo.adj_free;
                        hammer2_voldata_unlock(hmp);
                }

                /*
                 * Cleanup for next loop.
                 */
#ifdef HAMMER2_BULKFREE_TRANS
                hammer2_trans_done(hmp->spmp, 0);
#endif
                if (error & ~HAMMER2_ERROR_CHECK)
                        break;
                cbinfo.sbase = cbinfo.sstop;
                cbinfo.adj_free = 0;
        }
        kmem_free_swapbacked(&cbinfo.kp);
        kfree(cbinfo.dedup, M_HAMMER2);
        cbinfo.dedup = NULL;

        bfi->sstop = cbinfo.sbase;

        incr = bfi->sstop / (hmp->total_size / 10000);
        if (incr > 10000)
                incr = 10000;

        kprintf("bulkfree pass statistics (%d.%02d%% storage processed):\n",
                (int)incr / 100,
                (int)incr % 100);

        if (error & ~HAMMER2_ERROR_CHECK) {
                kprintf("    bulkfree was aborted\n");
        } else {
                if (error & HAMMER2_ERROR_CHECK) {
                        kprintf("    WARNING: bulkfree "
                                "encountered CRC errors\n");
                }
                kprintf("    transition->free   %ld\n", cbinfo.count_10_00);
                kprintf("    transition->staged %ld\n", cbinfo.count_11_10);
                kprintf("    ERR(00)->allocated %ld\n", cbinfo.count_00_11);
                kprintf("    ERR(01)->allocated %ld\n", cbinfo.count_01_11);
                kprintf("    staged->allocated  %ld\n", cbinfo.count_10_11);
                kprintf("    ~4MB segs cleaned  %ld\n", cbinfo.count_l0cleans);
                kprintf("    linear adjusts     %ld\n",
                        cbinfo.count_linadjusts);
                kprintf("    dedup factor       %ld\n",
                        cbinfo.count_dedup_factor);
                kprintf("    max saved chains   %ld\n", cbinfo.list_count_max);
        }

        return error;
}

static void
cbinfo_bmap_init(hammer2_bulkfree_info_t *cbinfo, size_t size)
{
        hammer2_bmap_data_t *bmap = cbinfo->bmap;
        hammer2_key_t key = cbinfo->sbase;
        hammer2_key_t lokey;
        hammer2_key_t hikey;

        lokey = (cbinfo->hmp->voldata.allocator_beg + HAMMER2_SEGMASK64) &
                ~HAMMER2_SEGMASK64;
        hikey = cbinfo->hmp->total_size & ~HAMMER2_SEGMASK64;

        bzero(bmap, size);
        while (size) {
                bzero(bmap, sizeof(*bmap));
                if (lokey < H2FMBASE(key, HAMMER2_FREEMAP_LEVEL1_RADIX))
                        lokey = H2FMBASE(key, HAMMER2_FREEMAP_LEVEL1_RADIX);
                if (lokey < H2FMZONEBASE(key) + HAMMER2_ZONE_SEG64)
                        lokey = H2FMZONEBASE(key) + HAMMER2_ZONE_SEG64;
                if (key < lokey || key >= hikey) {
                        memset(bmap->bitmapq, -1,
                               sizeof(bmap->bitmapq));
                        bmap->avail = 0;
                        bmap->linear = HAMMER2_SEGSIZE;
                } else {
                        bmap->avail = HAMMER2_FREEMAP_LEVEL0_SIZE;
                }
                size -= sizeof(*bmap);
                key += HAMMER2_FREEMAP_LEVEL0_SIZE;
                ++bmap;
        }
}

static int
h2_bulkfree_callback(hammer2_bulkfree_info_t *cbinfo, hammer2_blockref_t *bref)
{
        hammer2_bmap_data_t *bmap;
        hammer2_off_t data_off;
        uint16_t class;
        size_t bytes;
        int radix;

        /*
         * Check for signal and allow yield to userland during scan.
         */
        if (hammer2_signal_check(&cbinfo->save_time))
                return HAMMER2_ERROR_ABORTED;

        /*
         * Deal with kernel thread cpu or I/O hogging by limiting the
         * number of chains scanned per second to hammer2_bulkfree_tps.
         * Ignore leaf records (DIRENT and DATA), no per-record I/O is
         * involved for those since we don't load their data.
         */
        if (bref->type != HAMMER2_BREF_TYPE_DATA &&
            bref->type != HAMMER2_BREF_TYPE_DIRENT) {
                ++cbinfo->bulkfree_calls;
                if (cbinfo->bulkfree_calls > hammer2_bulkfree_tps) {
                        int dticks = ticks - cbinfo->bulkfree_ticks;
                        if (dticks < 0)
                                dticks = 0;
                        if (dticks < hz) {
                                tsleep(&cbinfo->bulkfree_ticks, 0,
                                       "h2bw", hz - dticks);
                        }
                        cbinfo->bulkfree_calls = 0;
                        cbinfo->bulkfree_ticks = ticks;
                }
        }

        /*
         * Calculate the data offset and determine if it is within
         * the current freemap range being gathered.
         */
        data_off = bref->data_off & ~HAMMER2_OFF_MASK_RADIX;
        if (data_off < cbinfo->sbase || data_off >= cbinfo->sstop)
                return 0;
        if (data_off < cbinfo->hmp->voldata.allocator_beg)
                return 0;
        if (data_off >= cbinfo->hmp->total_size)
                return 0;

        /*
         * Calculate the information needed to generate the in-memory
         * freemap record.
         *
         * Hammer2 does not allow allocations to cross the L1 (1GB) boundary,
         * it's a problem if it does.  (Or L0 (4MB) for that matter).
         */
        radix = (int)(bref->data_off & HAMMER2_OFF_MASK_RADIX);
        KKASSERT(radix != 0);
        bytes = (size_t)1 << radix;
        class = (bref->type << 8) | HAMMER2_PBUFRADIX;

        if (data_off + bytes > cbinfo->sstop) {
                kprintf("hammer2_bulkfree_scan: illegal 1GB boundary "
                        "%016jx %016jx/%d\n",
                        (intmax_t)bref->data_off,
                        (intmax_t)bref->key,
                        bref->keybits);
                bytes = cbinfo->sstop - data_off;       /* XXX */
        }

        /*
         * Convert to a storage offset relative to the beginning of the
         * storage range we are collecting.  Then lookup the level0 bmap entry.
         */
        data_off -= cbinfo->sbase;
        bmap = cbinfo->bmap + (data_off >> HAMMER2_FREEMAP_LEVEL0_RADIX);

        /*
         * Convert data_off to a bmap-relative value (~4MB storage range).
         * Adjust linear, class, and avail.
         *
         * Hammer2 does not allow allocations to cross the L0 (4MB) boundary,
         */
        data_off &= HAMMER2_FREEMAP_LEVEL0_MASK;
        if (data_off + bytes > HAMMER2_FREEMAP_LEVEL0_SIZE) {
                kprintf("hammer2_bulkfree_scan: illegal 4MB boundary "
                        "%016jx %016jx/%d\n",
                        (intmax_t)bref->data_off,
                        (intmax_t)bref->key,
                        bref->keybits);
                bytes = HAMMER2_FREEMAP_LEVEL0_SIZE - data_off;
        }

        if (bmap->class == 0) {
                bmap->class = class;
                bmap->avail = HAMMER2_FREEMAP_LEVEL0_SIZE;
        }

        /*
         * NOTE: bmap->class does not have to match class.  Classification
         *       is relaxed when free space is low, so some mixing can occur.
         */
#if 0
        /*
         * XXX removed
         */
        if (bmap->class != class) {
                kprintf("hammer2_bulkfree_scan: illegal mixed class "
                        "%016jx %016jx/%d (%04x vs %04x)\n",
                        (intmax_t)bref->data_off,
                        (intmax_t)bref->key,
                        bref->keybits,
                        class, bmap->class);
        }
#endif

        /*
         * Just record the highest byte-granular offset for now.  Do not
         * match against allocations which are in multiples of whole blocks.
         *
         * Make sure that any in-block linear offset at least covers the
         * data range.  This can cause bmap->linear to become block-aligned.
         */
        if (bytes & HAMMER2_FREEMAP_BLOCK_MASK) {
                if (bmap->linear < (int32_t)data_off + (int32_t)bytes)
                        bmap->linear = (int32_t)data_off + (int32_t)bytes;
        } else if (bmap->linear >= (int32_t)data_off &&
                   bmap->linear < (int32_t)data_off + (int32_t)bytes) {
                bmap->linear = (int32_t)data_off + (int32_t)bytes;
        }

        /*
         * Adjust the hammer2_bitmap_t bitmap[HAMMER2_BMAP_ELEMENTS].
         * 64-bit entries, 2 bits per entry, to code 11.
         *
         * NOTE: data_off mask to 524288, shift right by 14 (radix for 16384),
         *       and multiply shift amount by 2 for sets of 2 bits.
         *
         * NOTE: The allocation can be smaller than HAMMER2_FREEMAP_BLOCK_SIZE.
         *       also, data_off may not be FREEMAP_BLOCK_SIZE aligned.
         */
        while (bytes > 0) {
                hammer2_bitmap_t bmask;
                int bindex;

                bindex = (int)data_off >> (HAMMER2_FREEMAP_BLOCK_RADIX +
                                           HAMMER2_BMAP_INDEX_RADIX);
                bmask = (hammer2_bitmap_t)3 <<
                        ((((int)data_off & HAMMER2_BMAP_INDEX_MASK) >>
                         HAMMER2_FREEMAP_BLOCK_RADIX) << 1);

                /*
                 * NOTE! The (avail) calculation is bitmap-granular.  Multiple
                 *       sub-granular records can wind up at the same bitmap
                 *       position.
                 */
                if ((bmap->bitmapq[bindex] & bmask) == 0) {
                        if (bytes < HAMMER2_FREEMAP_BLOCK_SIZE) {
                                bmap->avail -= HAMMER2_FREEMAP_BLOCK_SIZE;
                        } else {
                                bmap->avail -= bytes;
                        }
                        bmap->bitmapq[bindex] |= bmask;
                }
                data_off += HAMMER2_FREEMAP_BLOCK_SIZE;
                if (bytes < HAMMER2_FREEMAP_BLOCK_SIZE)
                        bytes = 0;
                else
                        bytes -= HAMMER2_FREEMAP_BLOCK_SIZE;
        }
        return 0;
}

/*
 * Synchronize the in-memory bitmap with the live freemap.  This is not a
 * direct copy.  Instead the bitmaps must be compared:
 *
 *      In-memory       Live-freemap
 *         00             11 -> 10      (do nothing if live modified)
 *                        10 -> 00      (do nothing if live modified)
 *         11             10 -> 11      handles race against live
 *                        ** -> 11      nominally warn of corruption
 *
 * We must also fixup the hints in HAMMER2_BREF_TYPE_FREEMAP_LEAF.
 */
static int
h2_bulkfree_sync(hammer2_bulkfree_info_t *cbinfo)
{
        hammer2_off_t data_off;
        hammer2_key_t key;
        hammer2_key_t key_dummy;
        hammer2_bmap_data_t *bmap;
        hammer2_bmap_data_t *live;
        hammer2_chain_t *live_parent;
        hammer2_chain_t *live_chain;
        int bmapindex;
        int error;

        kprintf("hammer2_bulkfree - range ");

        if (cbinfo->sbase < cbinfo->hmp->voldata.allocator_beg)
                kprintf("%016jx-",
                        (intmax_t)cbinfo->hmp->voldata.allocator_beg);
        else
                kprintf("%016jx-",
                        (intmax_t)cbinfo->sbase);

        if (cbinfo->sstop > cbinfo->hmp->total_size)
                kprintf("%016jx\n",
                        (intmax_t)cbinfo->hmp->total_size);
        else
                kprintf("%016jx\n",
                        (intmax_t)cbinfo->sstop);

        data_off = cbinfo->sbase;
        bmap = cbinfo->bmap;

        live_parent = &cbinfo->hmp->fchain;
        hammer2_chain_ref(live_parent);
        hammer2_chain_lock(live_parent, HAMMER2_RESOLVE_ALWAYS);
        live_chain = NULL;
        error = 0;

        /*
         * Iterate each hammer2_bmap_data_t line (128 bytes) managing
         * 4MB of storage.
         */
        while (data_off < cbinfo->sstop) {
                /*
                 * The freemap is not used below allocator_beg or beyond
                 * total_size.
                 */

                if (data_off < cbinfo->hmp->voldata.allocator_beg)
                        goto next;
                if (data_off >= cbinfo->hmp->total_size)
                        goto next;

                /*
                 * Locate the freemap leaf on the live filesystem
                 */
                key = (data_off & ~HAMMER2_FREEMAP_LEVEL1_MASK);

                if (live_chain == NULL || live_chain->bref.key != key) {
                        if (live_chain) {
                                hammer2_chain_unlock(live_chain);
                                hammer2_chain_drop(live_chain);
                        }
                        live_chain = hammer2_chain_lookup(
                                            &live_parent,
                                            &key_dummy,
                                            key,
                                            key + HAMMER2_FREEMAP_LEVEL1_MASK,
                                            &error,
                                            HAMMER2_LOOKUP_ALWAYS);
                        if (error) {
                                kprintf("hammer2_bulkfree: freemap lookup "
                                        "error near %016jx, error %s\n",
                                        (intmax_t)data_off,
                                        hammer2_error_str(live_chain->error));
                                break;
                        }
                }
                if (live_chain == NULL) {
                        /*
                         * XXX if we implement a full recovery mode we need
                         * to create/recreate missing freemap chains if our
                         * bmap has any allocated blocks.
                         */
                        if (bmap->class &&
                            bmap->avail != HAMMER2_FREEMAP_LEVEL0_SIZE) {
                                kprintf("hammer2_bulkfree: cannot locate "
                                        "live leaf for allocated data "
                                        "near %016jx\n",
                                        (intmax_t)data_off);
                        }
                        goto next;
                }
                if (live_chain->error) {
                        kprintf("hammer2_bulkfree: unable to access freemap "
                                "near %016jx, error %s\n",
                                (intmax_t)data_off,
                                hammer2_error_str(live_chain->error));
                        hammer2_chain_unlock(live_chain);
                        hammer2_chain_drop(live_chain);
                        live_chain = NULL;
                        goto next;
                }

                bmapindex = (data_off & HAMMER2_FREEMAP_LEVEL1_MASK) >>
                            HAMMER2_FREEMAP_LEVEL0_RADIX;
                live = &live_chain->data->bmdata[bmapindex];

                /*
                 * Shortcut if the bitmaps match and the live linear
                 * indicator is sane.  We can't do a perfect check of
                 * live->linear because the only real requirement is that
                 * if it is not block-aligned, that it not cover the space
                 * within its current block which overlaps one of the data
                 * ranges we scan.  We don't retain enough fine-grained
                 * data in our scan to be able to set it exactly.
                 *
                 * TODO - we could shortcut this by testing that both
                 * live->class and bmap->class are 0, and both avails are
                 * set to HAMMER2_FREEMAP_LEVEL0_SIZE (4MB).
                 */
                if (bcmp(live->bitmapq, bmap->bitmapq,
                         sizeof(bmap->bitmapq)) == 0 &&
                    live->linear >= bmap->linear &&
                    (hammer2_aux_flags & 1) == 0 &&
                    bigmask_good(bmap, live_chain->bref.check.freemap.bigmask))
                {
                        goto next;
                }
                if (hammer2_debug & 1) {
                        kprintf("live %016jx %04d.%04x (avail=%d) "
                                "bigmask %08x->%08x\n",
                                data_off, bmapindex, live->class, live->avail,
                                live_chain->bref.check.freemap.bigmask,
                                live_chain->bref.check.freemap.bigmask |
                                bigmask_get(bmap));
                }

                if (hammer2_chain_modify(live_chain, cbinfo->mtid, 0, 0)) {
                        kprintf("hammer2_bulkfree: unable to modify freemap "
                                "at %016jx for data-block %016jx, error %s\n",
                                live_chain->bref.data_off,
                                (intmax_t)data_off,
                                hammer2_error_str(live_chain->error));
                        hammer2_chain_unlock(live_chain);
                        hammer2_chain_drop(live_chain);
                        live_chain = NULL;
                        goto next;
                }
                live_chain->bref.check.freemap.bigmask = -1;
                cbinfo->hmp->freemap_relaxed = 0;       /* reset heuristic */
                live = &live_chain->data->bmdata[bmapindex];

                h2_bulkfree_sync_adjust(cbinfo, data_off, live, bmap,
                                        live_chain->bref.key +
                                        bmapindex *
                                        HAMMER2_FREEMAP_LEVEL0_SIZE);
next:
                data_off += HAMMER2_FREEMAP_LEVEL0_SIZE;
                ++bmap;
        }
        if (live_chain) {
                hammer2_chain_unlock(live_chain);
                hammer2_chain_drop(live_chain);
        }
        if (live_parent) {
                hammer2_chain_unlock(live_parent);
                hammer2_chain_drop(live_parent);
        }
        return error;
}

/*
 * Merge the bulkfree bitmap against the existing bitmap.
 */
static
void
h2_bulkfree_sync_adjust(hammer2_bulkfree_info_t *cbinfo,
                        hammer2_off_t data_off, hammer2_bmap_data_t *live,
                        hammer2_bmap_data_t *bmap, hammer2_key_t alloc_base)
{
        int bindex;
        int scount;
        hammer2_off_t tmp_off;
        hammer2_bitmap_t lmask;
        hammer2_bitmap_t mmask;

        tmp_off = data_off;

        for (bindex = 0; bindex < HAMMER2_BMAP_ELEMENTS; ++bindex) {
                lmask = live->bitmapq[bindex];  /* live */
                mmask = bmap->bitmapq[bindex];  /* snapshotted bulkfree */
                if (lmask == mmask) {
                        tmp_off += HAMMER2_BMAP_INDEX_SIZE;
                        continue;
                }

                for (scount = 0;
                     scount < HAMMER2_BMAP_BITS_PER_ELEMENT;
                     scount += 2) {
                        if ((mmask & 3) == 0) {
                                /*
                                 * in-memory 00         live 11 -> 10
                                 *                      live 10 -> 00
                                 *
                                 * Storage might be marked allocated or
                                 * staged and must be remarked staged or
                                 * free.
                                 */
                                switch (lmask & 3) {
                                case 0: /* 00 */
                                        break;
                                case 1: /* 01 */
                                        kprintf("hammer2_bulkfree: cannot "
                                                "transition m=00/l=01\n");
                                        break;
                                case 2: /* 10 -> 00 */
                                        live->bitmapq[bindex] &=
                                            ~((hammer2_bitmap_t)2 << scount);
                                        live->avail +=
                                                HAMMER2_FREEMAP_BLOCK_SIZE;
                                        if (live->avail >
                                            HAMMER2_FREEMAP_LEVEL0_SIZE) {
                                                live->avail =
                                                    HAMMER2_FREEMAP_LEVEL0_SIZE;
                                        }
                                        cbinfo->adj_free +=
                                                HAMMER2_FREEMAP_BLOCK_SIZE;
                                        ++cbinfo->count_10_00;
                                        hammer2_io_dedup_assert(
                                                cbinfo->hmp,
                                                tmp_off |
                                                HAMMER2_FREEMAP_BLOCK_RADIX,
                                                HAMMER2_FREEMAP_BLOCK_SIZE);
                                        break;
                                case 3: /* 11 -> 10 */
                                        live->bitmapq[bindex] &=
                                            ~((hammer2_bitmap_t)1 << scount);
                                        ++cbinfo->count_11_10;
                                        hammer2_io_dedup_delete(
                                                cbinfo->hmp,
                                                HAMMER2_BREF_TYPE_DATA,
                                                tmp_off |
                                                HAMMER2_FREEMAP_BLOCK_RADIX,
                                                HAMMER2_FREEMAP_BLOCK_SIZE);
                                        break;
                                }
                        } else if ((mmask & 3) == 3) {
                                /*
                                 * in-memory 11         live 10 -> 11
                                 *                      live ** -> 11
                                 *
                                 * Storage might be incorrectly marked free
                                 * or staged and must be remarked fully
                                 * allocated.
                                 */
                                switch (lmask & 3) {
                                case 0: /* 00 */
                                        /*
                                         * This case is not supposed to
                                         * happen.  If it does, it means
                                         * that an allocated block was
                                         * thought by the filesystem to be
                                         * free.
                                         */
                                        kprintf("hammer2_bulkfree: "
                                                "00->11 critical freemap "
                                                "transition for datablock "
                                                "%016jx\n",
                                                tmp_off);
                                        ++cbinfo->count_00_11;
                                        cbinfo->adj_free -=
                                                HAMMER2_FREEMAP_BLOCK_SIZE;
                                        live->avail -=
                                                HAMMER2_FREEMAP_BLOCK_SIZE;
                                        if ((int32_t)live->avail < 0)
                                                live->avail = 0;
                                        break;
                                case 1: /* 01 */
                                        ++cbinfo->count_01_11;
                                        break;
                                case 2: /* 10 -> 11 */
                                        ++cbinfo->count_10_11;
                                        break;
                                case 3: /* 11 */
                                        break;
                                }
                                live->bitmapq[bindex] |=
                                        ((hammer2_bitmap_t)3 << scount);
                        }
                        mmask >>= 2;
                        lmask >>= 2;
                        tmp_off += HAMMER2_FREEMAP_BLOCK_SIZE;
                }
        }

        /*
         * Determine if the live bitmap is completely free and reset its
         * fields if so.  Otherwise check to see if we can reduce the linear
         * offset.
         */
        for (bindex = HAMMER2_BMAP_ELEMENTS - 1; bindex >= 0; --bindex) {
                if (live->bitmapq[bindex] != 0)
                        break;
        }
        if (bindex < 0) {
                /*
                 * Completely empty, reset entire segment
                 */
#if 0
                kprintf("hammer2: cleanseg %016jx.%04x (%d)\n",
                        alloc_base, live->class, live->avail);
#endif
                live->avail = HAMMER2_FREEMAP_LEVEL0_SIZE;
                live->class = 0;
                live->linear = 0;
                ++cbinfo->count_l0cleans;
        } else if (bindex < 7) {
                /*
                 * Partially full, bitmapq[bindex] != 0.  Our bulkfree pass
                 * does not record enough information to set live->linear
                 * exactly.
                 *
                 * NOTE: Setting live->linear to a sub-block (16K) boundary
                 *       forces the live code to iterate to the next fully
                 *       free block.  It does NOT mean that all blocks above
                 *       live->linear are available.
                 *
                 *       Setting live->linear to a fragmentary (less than
                 *       16K) boundary allows allocations to iterate within
                 *       that sub-block.
                 */
                if (live->linear < bmap->linear &&
                    ((live->linear ^ bmap->linear) &
                     ~HAMMER2_FREEMAP_BLOCK_MASK) == 0) {
                        /*
                         * If greater than but still within the same
                         * sub-block as live we can adjust linear upward.
                         */
                        live->linear = bmap->linear;
                        ++cbinfo->count_linadjusts;
                } else {
                        /*
                         * Otherwise adjust to the nearest higher or same
                         * sub-block boundary.  The live system may have
                         * bounced live->linear around so we cannot make any
                         * assumptions with regards to available fragmentary
                         * allocations.
                         */
                        live->linear =
                                (bmap->linear + HAMMER2_FREEMAP_BLOCK_MASK) &
                                ~HAMMER2_FREEMAP_BLOCK_MASK;
                        ++cbinfo->count_linadjusts;
                }
        } else {
                /*
                 * Completely full, effectively disable the linear iterator
                 */
                live->linear = HAMMER2_SEGSIZE;
        }

#if 0
        if (bmap->class) {
                kprintf("%016jx %04d.%04x (avail=%7d) "
                        "%08x %08x %08x %08x %08x %08x %08x %08x\n",
                        (intmax_t)data_off,
                        (int)((data_off &
                               HAMMER2_FREEMAP_LEVEL1_MASK) >>
                              HAMMER2_FREEMAP_LEVEL0_RADIX),
                        bmap->class,
                        bmap->avail,
                        bmap->bitmap[0], bmap->bitmap[1],
                        bmap->bitmap[2], bmap->bitmap[3],
                        bmap->bitmap[4], bmap->bitmap[5],
                        bmap->bitmap[6], bmap->bitmap[7]);
        }
#endif
}

/*
 * BULKFREE DEDUP HEURISTIC
 *
 * WARNING! This code is SMP safe but the heuristic allows SMP collisions.
 *          All fields must be loaded into locals and validated.
 */
static
int
h2_bulkfree_test(hammer2_bulkfree_info_t *cbinfo, hammer2_blockref_t *bref,
                 int pri, int saved_error)
{
        hammer2_dedup_t *dedup;
        int best;
        int n;
        int i;

        n = hammer2_icrc32(&bref->data_off, sizeof(bref->data_off));
        dedup = cbinfo->dedup + (n & (HAMMER2_DEDUP_HEUR_MASK & ~7));

        for (i = best = 0; i < 8; ++i) {
                if (dedup[i].data_off == bref->data_off) {
                        if (dedup[i].ticks < pri)
                                dedup[i].ticks = pri;
                        if (pri == 1)
                                cbinfo->count_dedup_factor += dedup[i].ticks;
                        return (dedup[i].saved_error | HAMMER2_ERROR_EOF);
                }
                if (dedup[i].ticks < dedup[best].ticks)
                        best = i;
        }
        dedup[best].data_off = bref->data_off;
        dedup[best].ticks = pri;
        dedup[best].saved_error = saved_error;

        return 0;
}

/*
 * Calculate what the bigmask should be.  bigmask is permissive, so the
 * bits returned must be set at a minimum in the live bigmask.  Other bits
 * might also be set in the live bigmask.
 */
static uint32_t
bigmask_get(hammer2_bmap_data_t *bmap)
{
        hammer2_bitmap_t mask;  /* 64-bit mask to check */
        hammer2_bitmap_t scan;
        uint32_t bigmask;
        uint32_t radix_mask;
        int iter;
        int i;
        int j;

        bigmask = 0;
        for (i = 0; i < HAMMER2_BMAP_ELEMENTS; ++i) {
                mask = bmap->bitmapq[i];

                radix_mask = 1U << HAMMER2_FREEMAP_BLOCK_RADIX;
                radix_mask |= radix_mask - 1;
                iter = 2;       /* each bitmap entry is 2 bits. 2, 4, 8... */
                while (iter <= HAMMER2_BMAP_BITS_PER_ELEMENT) {
                        if (iter == HAMMER2_BMAP_BITS_PER_ELEMENT)
                                scan = -1;
                        else
                                scan = (1LU << iter) - 1;
                        j = 0;
                        while (j < HAMMER2_BMAP_BITS_PER_ELEMENT) {
                                /*
                                 * Check if all bits are 0 (free block).
                                 * If so, set the bit in bigmask for the
                                 * allocation radix under test.
                                 */
                                if ((scan & mask) == 0) {
                                        bigmask |= radix_mask;
                                }
                                scan <<= iter;
                                j += iter;
                        }
                        iter <<= 1;
                        radix_mask = (radix_mask << 1) | 1;
                }
        }
        return bigmask;
}

static int
bigmask_good(hammer2_bmap_data_t *bmap, uint32_t live_bigmask)
{
        uint32_t bigmask;

        bigmask = bigmask_get(bmap);
        return ((live_bigmask & bigmask) == bigmask);
}