/*
 * Copyright (c) 2003-2005 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/fcntl.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/ubc.h>
#include <sys/vnode.h>
#include <sys/vnode_internal.h>
#include <sys/kauth.h>

#include <hfs/hfs.h>
#include <hfs/hfs_endian.h>
#include <hfs/hfs_format.h>
#include <hfs/hfs_mount.h>
#include <hfs/hfs_hotfiles.h>

#include "hfscommon/headers/BTreeScanner.h"


#define HFC_DEBUG  0
#define HFC_VERBOSE 0



/*
 * Hot File List (runtime).
 */
typedef struct hotfileinfo {
        u_int32_t  hf_fileid;
        u_int32_t  hf_temperature;
        u_int32_t  hf_blocks;
} hotfileinfo_t;

typedef struct hotfilelist {
        u_int32_t     hfl_magic;
        u_int32_t     hfl_version;
        time_t        hfl_duration;    /* duration of sample period */
        int           hfl_count;       /* count of hot files recorded */
        int           hfl_next;        /* next file to move */
        int           hfl_totalblocks; /* total hot file blocks */
        int           hfl_reclaimblks; /* blocks to reclaim in HFV */
        u_int32_t     hfl_spare[2];
        hotfileinfo_t hfl_hotfile[1];  /* array of hot files */
} hotfilelist_t;


/*
 * Hot File Entry (runtime).
 */
typedef struct hotfile_entry {
        struct  hotfile_entry  *left;
        struct  hotfile_entry  *right;
        u_int32_t  fileid;
        u_int32_t  temperature;
        u_int32_t  blocks;
} hotfile_entry_t;

/*
 * Hot File Recording Data (runtime).
 */
typedef struct hotfile_data {
        struct hfsmount *hfsmp;
        long             refcount;
        int              activefiles;  /* active number of hot files */
        u_int32_t        threshold;
        u_int32_t        maxblocks;
        hotfile_entry_t *rootentry;
        hotfile_entry_t *freelist;
        hotfile_entry_t *coldest;
        hotfile_entry_t  entries[1];
} hotfile_data_t;

static int  hfs_recording_start (struct hfsmount *);
static int  hfs_recording_stop (struct hfsmount *);


/*
 * Hot File Data recording functions (in-memory binary tree).
 */
static void              hf_insert (hotfile_data_t *, hotfile_entry_t *);
static void              hf_delete (hotfile_data_t *, u_int32_t, u_int32_t);
static hotfile_entry_t * hf_coldest (hotfile_data_t *);
static hotfile_entry_t * hf_getnewentry (hotfile_data_t *);
static void              hf_getsortedlist (hotfile_data_t *, hotfilelist_t *);

#if HFC_DEBUG
static hotfile_entry_t * hf_lookup (hotfile_data_t *, u_int32_t, u_int32_t);
static void  hf_maxdepth(hotfile_entry_t *, int, int *);
static void  hf_printtree (hotfile_entry_t *);
#endif

/*
 * Hot File misc support functions.
 */
static int  hotfiles_collect (struct hfsmount *);
static int  hotfiles_age (struct hfsmount *);
static int  hotfiles_adopt (struct hfsmount *);
static int  hotfiles_evict (struct hfsmount *, struct proc *);
static int  hotfiles_refine (struct hfsmount *);
static int  hotextents(struct hfsmount *, HFSPlusExtentDescriptor *);
static int  hfs_addhotfile_internal(struct vnode *);


/*
 * Hot File Cluster B-tree (on disk) functions.
 */
static int  hfc_btree_create (struct hfsmount *, int, int);
static int  hfc_btree_open (struct hfsmount *, struct vnode **);
static int  hfc_btree_close (struct hfsmount *, struct vnode *);
static int  hfc_comparekeys (HotFileKey *, HotFileKey *);


char hfc_tag[] = "CLUSTERED HOT FILES B-TREE     ";

extern int  UBCINFOEXISTS(struct vnode * vp);
extern int  hfs_vnop_write(struct vnop_write_args *ap);


/*
 *========================================================================
 *                       HOT FILE INTERFACE ROUTINES
 *========================================================================
 */

/*
 * Start recording the hotest files on a file system.
 *
 * Requires that the hfc_mutex be held.
 */
static int
hfs_recording_start(struct hfsmount *hfsmp)
{
        hotfile_data_t *hotdata;
        struct timeval tv;
        int maxentries;
        size_t size;
        int i;
        int error;

        if ((hfsmp->hfs_flags & HFS_READ_ONLY) ||
            (hfsmp->jnl == NULL) ||
            (hfsmp->hfs_flags & HFS_METADATA_ZONE) == 0) {
                return (EPERM);
        }
        if (HFSTOVCB(hfsmp)->freeBlocks < (2 * (u_int32_t)hfsmp->hfs_hotfile_maxblks)) {
                return (ENOSPC);
        }
        if (hfsmp->hfc_stage != HFC_IDLE) {
                return (EBUSY);
        }
        hfsmp->hfc_stage = HFC_BUSY;

        /*
         * Dump previous recording data.
         */
        if (hfsmp->hfc_recdata) {
                void * tmp;

                tmp = hfsmp->hfc_recdata;
                hfsmp->hfc_recdata = NULL;
                FREE(tmp, M_TEMP);
        }

        microuptime(&tv);

        /*
         * On first startup check for suspended recording.
         */
        if (hfsmp->hfc_timebase == 0 &&
            hfc_btree_open(hfsmp, &hfsmp->hfc_filevp) == 0) {
                HotFilesInfo hotfileinfo;

                if ((BTGetUserData(VTOF(hfsmp->hfc_filevp), &hotfileinfo,
                                   sizeof(hotfileinfo)) == 0) &&
                    (SWAP_BE32 (hotfileinfo.magic) == HFC_MAGIC) &&
                    (SWAP_BE32 (hotfileinfo.timeleft) > 0) &&
                    (SWAP_BE32 (hotfileinfo.timebase) > 0)) {
                        hfsmp->hfc_maxfiles = SWAP_BE32 (hotfileinfo.maxfilecnt);
                        hfsmp->hfc_timeout = SWAP_BE32 (hotfileinfo.timeleft) + tv.tv_sec ;
                        hfsmp->hfc_timebase = SWAP_BE32 (hotfileinfo.timebase);
#if HFC_VERBOSE
                        printf("Resume recording hot files on %s (%d secs left)\n",
                                hfsmp->vcbVN, SWAP_BE32 (hotfileinfo.timeleft));
#endif
                } else {
                        hfsmp->hfc_maxfiles = HFC_DEFAULT_FILE_COUNT;
                        hfsmp->hfc_timebase = tv.tv_sec + 1;
                        hfsmp->hfc_timeout = hfsmp->hfc_timebase + HFC_DEFAULT_DURATION;
                }
                (void) hfc_btree_close(hfsmp, hfsmp->hfc_filevp);
                hfsmp->hfc_filevp = NULL;
        } else {
                struct cat_attr cattr;
                u_int32_t cnid;

                /*
                 * Make sure a btree file exists.
                 */
                cnid = GetFileInfo(HFSTOVCB(hfsmp), kRootDirID, HFC_FILENAME, &cattr, NULL);
                if ((cnid == 0) &&
                    !S_ISREG(cattr.ca_mode) &&
                    (error = hfc_btree_create(hfsmp, HFSTOVCB(hfsmp)->blockSize, HFC_DEFAULT_FILE_COUNT))) {
                        hfsmp->hfc_stage = HFC_IDLE;
                        wakeup((caddr_t)&hfsmp->hfc_stage);
                        return (error);
                }
#if HFC_VERBOSE
                printf("HFS: begin recording hot files on %s\n", hfsmp->vcbVN);
#endif
                hfsmp->hfc_maxfiles = HFC_DEFAULT_FILE_COUNT;
                hfsmp->hfc_timeout = tv.tv_sec + HFC_DEFAULT_DURATION;

                /* Reset time base.  */
                if (hfsmp->hfc_timebase == 0) {
                        hfsmp->hfc_timebase = tv.tv_sec + 1;
                } else {
                        time_t cumulativebase;

                        cumulativebase = hfsmp->hfc_timeout - (HFC_CUMULATIVE_CYCLES * HFC_DEFAULT_DURATION);
                        hfsmp->hfc_timebase = MAX(hfsmp->hfc_timebase, cumulativebase);
                }
        }

        if ((hfsmp->hfc_maxfiles == 0) ||
            (hfsmp->hfc_maxfiles > HFC_MAXIMUM_FILE_COUNT)) {
                hfsmp->hfc_maxfiles = HFC_DEFAULT_FILE_COUNT;
        }
        maxentries = hfsmp->hfc_maxfiles;

        size = sizeof(hotfile_data_t) + (maxentries * sizeof(hotfile_entry_t));
        MALLOC(hotdata, hotfile_data_t *, size, M_TEMP, M_WAITOK);
        bzero(hotdata, size);

        for (i = 1; i < maxentries ; i++)
                hotdata->entries[i-1].right = &hotdata->entries[i];
        
        hotdata->freelist = &hotdata->entries[0];
        /* 
         * Establish minimum temperature and maximum file size.
         */
        hotdata->threshold = HFC_MINIMUM_TEMPERATURE;
        hotdata->maxblocks = HFC_MAXIMUM_FILESIZE / HFSTOVCB(hfsmp)->blockSize;
        hotdata->hfsmp = hfsmp;
        
        hfsmp->hfc_recdata = hotdata;
        hfsmp->hfc_stage = HFC_RECORDING;
        wakeup((caddr_t)&hfsmp->hfc_stage);
        return (0);
}

/*
 * Stop recording the hotest files on a file system.
 *
 * Requires that the hfc_mutex be held.
 */
static int
hfs_recording_stop(struct hfsmount *hfsmp)
{
        hotfile_data_t *hotdata;
        hotfilelist_t  *listp;
        struct timeval tv;
        size_t  size;
        enum hfc_stage newstage = HFC_IDLE;
        int  error;

        if (hfsmp->hfc_stage != HFC_RECORDING)
                return (EPERM);

        hotfiles_collect(hfsmp);

        if (hfsmp->hfc_stage != HFC_RECORDING)
                return (0);

        hfsmp->hfc_stage = HFC_BUSY;

        /*
         * Convert hot file data into a simple file id list....
         *
         * then dump the sample data
         */
#if HFC_VERBOSE
        printf("HFS: end of hot file recording on %s\n", hfsmp->vcbVN);
#endif
        hotdata = (hotfile_data_t *)hfsmp->hfc_recdata;
        if (hotdata == NULL)
                return (0);
        hfsmp->hfc_recdata = NULL;
        hfsmp->hfc_stage = HFC_EVALUATION;
        wakeup((caddr_t)&hfsmp->hfc_stage);

#if HFC_VERBOSE
        printf("  curentries: %d\n", hotdata->activefiles);
#endif
        /*
         * If no hot files recorded then we're done.
         */
        if (hotdata->rootentry == NULL) {
                error = 0;
                goto out;
        }

        /* Open the B-tree file for writing... */
        if (hfsmp->hfc_filevp)
                panic("hfs_recording_stop: hfc_filevp exists (vp = 0x%08x)", hfsmp->hfc_filevp);

        error = hfc_btree_open(hfsmp, &hfsmp->hfc_filevp);
        if (error) {
                goto out;
        }

        /*
         * Age the previous set of clustered hot files.
         */
        error = hotfiles_age(hfsmp);
        if (error) {
                (void) hfc_btree_close(hfsmp, hfsmp->hfc_filevp);
                hfsmp->hfc_filevp = NULL;
                goto out;
        }

        /*
         * Create a sorted list of hotest files.
         */
        size = sizeof(hotfilelist_t);
        size += sizeof(hotfileinfo_t) * (hotdata->activefiles - 1);
        MALLOC(listp, hotfilelist_t *, size, M_TEMP, M_WAITOK);
        bzero(listp, size);

        hf_getsortedlist(hotdata, listp);       /* NOTE: destroys hot file tree! */
        microuptime(&tv);
        listp->hfl_duration = tv.tv_sec - hfsmp->hfc_timebase;
        hfsmp->hfc_recdata = listp;

        /*
         * Account for duplicates.
         */
        error = hotfiles_refine(hfsmp);
        if (error) {
                (void) hfc_btree_close(hfsmp, hfsmp->hfc_filevp);
                hfsmp->hfc_filevp = NULL;
                goto out;
        }

        /*
         * Compute the amount of space to reclaim...
         */
        if (listp->hfl_totalblocks > hfsmp->hfs_hotfile_freeblks) {
                listp->hfl_reclaimblks =
                        MIN(listp->hfl_totalblocks, hfsmp->hfs_hotfile_maxblks) -
                        hfsmp->hfs_hotfile_freeblks;
#if HFC_VERBOSE
                printf("hfs_recording_stop: need to reclaim %d blocks\n", listp->hfl_reclaimblks);
#endif
                if (listp->hfl_reclaimblks)
                        newstage = HFC_EVICTION;
                else
                        newstage = HFC_ADOPTION;
        } else {
                newstage = HFC_ADOPTION;
        }
        
        if (newstage == HFC_ADOPTION && listp->hfl_totalblocks == 0) {
                (void) hfc_btree_close(hfsmp, hfsmp->hfc_filevp);
                hfsmp->hfc_filevp = NULL;
                newstage = HFC_IDLE;
        }
out:
#if HFC_VERBOSE
        if (newstage == HFC_EVICTION)
                printf("HFS: evicting coldest files\n");
        else if (newstage == HFC_ADOPTION)
                printf("HFS: adopting hotest files\n");
#endif
        FREE(hotdata, M_TEMP);

        hfsmp->hfc_stage = newstage;
        wakeup((caddr_t)&hfsmp->hfc_stage);
        return (error);
}

/*
 * Suspend recording the hotest files on a file system.
 */
__private_extern__
int
hfs_recording_suspend(struct hfsmount *hfsmp)
{
        HotFilesInfo hotfileinfo;
        hotfile_data_t *hotdata = NULL;
        struct timeval tv;
        int  error;

        if (hfsmp->hfc_stage == HFC_DISABLED)
                return (0);

        lck_mtx_lock(&hfsmp->hfc_mutex);

        /*
         * XXX NOTE
         * A suspend can occur during eval/evict/adopt stage.
         * In that case we would need to write out info and
         * flush our HFBT vnode. Currently we just bail.
         */

        hotdata = (hotfile_data_t *)hfsmp->hfc_recdata;
        if (hotdata == NULL || hfsmp->hfc_stage != HFC_RECORDING) {
                error = 0;
                goto out;
        }
        hfsmp->hfc_stage = HFC_BUSY;

#if HFC_VERBOSE
        printf("HFS: suspend hot file recording on %s\n", hfsmp->vcbVN);
#endif
        error = hfc_btree_open(hfsmp, &hfsmp->hfc_filevp);
        if (error) {
                printf("hfs_recording_suspend: err %d opening btree\n", error);
                goto out;
        }

        if (hfs_start_transaction(hfsmp) != 0) {
            error = EINVAL;
            goto out;
        }
        if (hfs_lock(VTOC(hfsmp->hfc_filevp), HFS_EXCLUSIVE_LOCK) != 0) {
                error = EPERM;
                goto out;
        }

        microuptime(&tv);
        hotfileinfo.magic       = SWAP_BE32 (HFC_MAGIC);
        hotfileinfo.version     = SWAP_BE32 (HFC_VERSION);
        hotfileinfo.duration    = SWAP_BE32 (HFC_DEFAULT_DURATION);
        hotfileinfo.timebase    = SWAP_BE32 (hfsmp->hfc_timebase);
        hotfileinfo.timeleft    = SWAP_BE32 (hfsmp->hfc_timeout - tv.tv_sec);
        hotfileinfo.threshold   = SWAP_BE32 (hotdata->threshold);
        hotfileinfo.maxfileblks = SWAP_BE32 (hotdata->maxblocks);
        hotfileinfo.maxfilecnt  = SWAP_BE32 (HFC_DEFAULT_FILE_COUNT);
        strcpy(hotfileinfo.tag, hfc_tag);
        (void) BTSetUserData(VTOF(hfsmp->hfc_filevp), &hotfileinfo, sizeof(hotfileinfo));

        hfs_unlock(VTOC(hfsmp->hfc_filevp));
        hfs_end_transaction(hfsmp);
out:
        if (hfsmp->hfc_filevp) {
                (void) hfc_btree_close(hfsmp, hfsmp->hfc_filevp);
                hfsmp->hfc_filevp = NULL;
        }
        if (hotdata) {
                FREE(hotdata, M_TEMP);
                hfsmp->hfc_recdata = NULL;
        }
        hfsmp->hfc_stage = HFC_DISABLED;
        wakeup((caddr_t)&hfsmp->hfc_stage);
exit:
        lck_mtx_unlock(&hfsmp->hfc_mutex);
        return (error);
}


/*
 *
 */
__private_extern__
int
hfs_recording_init(struct hfsmount *hfsmp)
{
        CatalogKey * keyp;
        CatalogRecord * datap;
        u_int32_t  dataSize;
        HFSPlusCatalogFile *filep;
        BTScanState scanstate;
        BTreeIterator * iterator;
        FSBufferDescriptor  record;
        HotFileKey * key;
        filefork_t * filefork;
        u_int32_t  data;
        struct cat_attr cattr;
        u_int32_t  cnid;
        int error = 0;

        int inserted = 0;  /* debug variables */
        int filecount = 0;

        /*
         * For now, only the boot volume is supported.
         */
        if ((vfs_flags(HFSTOVFS(hfsmp)) & MNT_ROOTFS) == 0) {
                hfsmp->hfc_stage = HFC_DISABLED;
                return (EPERM);
        }

        /*
         * If the Hot File btree exists then metadata zone is ready.
         */
        cnid = GetFileInfo(HFSTOVCB(hfsmp), kRootDirID, HFC_FILENAME, &cattr, NULL);
        if (cnid != 0 && S_ISREG(cattr.ca_mode)) {
                if (hfsmp->hfc_stage == HFC_DISABLED)
                        hfsmp->hfc_stage = HFC_IDLE;
                return (0);
        }
        error = hfc_btree_create(hfsmp, HFSTOVCB(hfsmp)->blockSize, HFC_DEFAULT_FILE_COUNT);
        if (error) {
#if HFC_VERBOSE
                printf("Error %d creating hot file b-tree on %s \n", error, hfsmp->vcbVN);
#endif
                return (error);
        }
        /*
         * Open the Hot File B-tree file for writing.
         */
        if (hfsmp->hfc_filevp)
                panic("hfs_recording_init: hfc_filevp exists (vp = 0x%08x)", hfsmp->hfc_filevp);
        error = hfc_btree_open(hfsmp, &hfsmp->hfc_filevp);
        if (error) {
#if HFC_VERBOSE
                printf("Error %d opening hot file b-tree on %s \n", error, hfsmp->vcbVN);
#endif
                return (error);
        }
        MALLOC(iterator, BTreeIterator *, sizeof(*iterator), M_TEMP, M_WAITOK);
        bzero(iterator, sizeof(*iterator));
        key = (HotFileKey*) &iterator->key;
        key->keyLength = HFC_KEYLENGTH;

        record.bufferAddress = &data;
        record.itemSize = sizeof(u_int32_t);
        record.itemCount = 1;
#if HFC_VERBOSE
        printf("Evaluating space for \"%s\" metadata zone...\n", HFSTOVCB(hfsmp)->vcbVN);
#endif
        /*
         * Get ready to scan the Catalog file.
         */
        error = BTScanInitialize(VTOF(HFSTOVCB(hfsmp)->catalogRefNum), 0, 0, 0,
                               kCatSearchBufferSize, &scanstate);
        if (error) {
                printf("hfs_recording_init: err %d BTScanInit\n", error);
                goto out2;
        }

        /*
         * The writes to Hot File B-tree file are journaled.
         */
        if (hfs_start_transaction(hfsmp) != 0) {
            error = EINVAL;
            goto out1;
        } 
        if (hfs_lock(VTOC(hfsmp->hfc_filevp), HFS_EXCLUSIVE_LOCK) != 0) {
                error = EPERM;
                goto out1;
        }
        filefork = VTOF(hfsmp->hfc_filevp);

        /*
         * Visit all the catalog btree leaf records.
         */
        for (;;) {
                error = BTScanNextRecord(&scanstate, 0, (void **)&keyp, (void **)&datap, &dataSize);
                if (error) {
                        if (error == btNotFound)
                                error = 0;
                        else
                                printf("hfs_recording_init: err %d BTScanNext\n", error);
                        break;
                }
                if ((datap->recordType != kHFSPlusFileRecord) ||
                    (dataSize != sizeof(HFSPlusCatalogFile))) {
                        continue;
                }
                filep = (HFSPlusCatalogFile *)datap;
                filecount++;
                if (filep->dataFork.totalBlocks == 0) {
                        continue;
                }
                /*
                 * Any file that has blocks inside the hot file
                 * space is recorded for later eviction.
                 *
                 * For now, resource forks are ignored.
                 */
                if (!hotextents(hfsmp, &filep->dataFork.extents[0])) {
                        continue;
                }
                cnid = filep->fileID;

                /* Skip over journal files. */
                if (cnid == hfsmp->hfs_jnlfileid || cnid == hfsmp->hfs_jnlinfoblkid) {
                        continue;
                }
                /*
                 * XXX - need to skip quota files as well.
                 */

                /* Insert a hot file entry. */
                key->keyLength   = HFC_KEYLENGTH;
                key->temperature = HFC_MINIMUM_TEMPERATURE;
                key->fileID      = cnid;
                key->forkType    = 0;
                data = 0x3f3f3f3f;
                error = BTInsertRecord(filefork, iterator, &record, record.itemSize);
                if (error) {
                        printf("hfs_recording_init: BTInsertRecord failed %d (fileid %d)\n", error, key->fileID);
                        error = MacToVFSError(error);
                        break;
                }

                /* Insert the corresponding thread record. */
                key->keyLength = HFC_KEYLENGTH;
                key->temperature = HFC_LOOKUPTAG;
                key->fileID = cnid;
                key->forkType = 0;
                data = HFC_MINIMUM_TEMPERATURE;
                error = BTInsertRecord(filefork, iterator, &record, record.itemSize);
                if (error) {
                        printf("hfs_recording_init: BTInsertRecord failed %d (fileid %d)\n", error, key->fileID);
                        error = MacToVFSError(error);
                        break;
                }
                inserted++;
        }
        (void) BTFlushPath(filefork);
        hfs_unlock(VTOC(hfsmp->hfc_filevp));

        hfs_end_transaction(hfsmp);
#if HFC_VERBOSE
        printf("%d files identified out of %d\n", inserted, filecount);
#endif
        
out1:
        (void) BTScanTerminate(&scanstate, &data, &data, &data);
out2:   
        FREE(iterator, M_TEMP);
        if (hfsmp->hfc_filevp) {
                (void) hfc_btree_close(hfsmp, hfsmp->hfc_filevp);
                hfsmp->hfc_filevp = NULL;
        }
        if (error == 0)
                hfsmp->hfc_stage = HFC_IDLE;

        return (error);
}

/*
 * Use sync to perform ocassional background work.
 */
__private_extern__
int
hfs_hotfilesync(struct hfsmount *hfsmp, struct proc *p)
{
        if (hfsmp->hfc_stage) {
                struct timeval tv;

                lck_mtx_lock(&hfsmp->hfc_mutex);

                switch (hfsmp->hfc_stage) {
                case HFC_IDLE:
                        (void) hfs_recording_start(hfsmp);
                        break;
        
                case HFC_RECORDING:
                        microuptime(&tv);
                        if (tv.tv_sec > hfsmp->hfc_timeout)
                                (void) hfs_recording_stop(hfsmp);
                        break;
        
                case HFC_EVICTION:
                        (void) hotfiles_evict(hfsmp, p);
                        break;
        
                case HFC_ADOPTION:
                        (void) hotfiles_adopt(hfsmp);
                        break;
                default:
                        break;
                }

                lck_mtx_unlock(&hfsmp->hfc_mutex);
        }
        return (0);
}

/*
 * Add a hot file to the recording list.
 *
 * This can happen when a hot file gets reclaimed or at the
 * end of the recording period for any active hot file.
 *
 * NOTE: Since both the data and resource fork can  be hot,
 * there can be two entries for the same file id.
 *
 * Note: the cnode is locked on entry.
 */
__private_extern__
int
hfs_addhotfile(struct vnode *vp)
{
        hfsmount_t *hfsmp;
        int error;

        hfsmp = VTOHFS(vp);
        if (hfsmp->hfc_stage != HFC_RECORDING)
                return (0);

        lck_mtx_lock(&hfsmp->hfc_mutex);
        error = hfs_addhotfile_internal(vp);
        lck_mtx_unlock(&hfsmp->hfc_mutex);
        return (error);
}

static int
hfs_addhotfile_internal(struct vnode *vp)
{
        hotfile_data_t *hotdata;
        hotfile_entry_t *entry;
        hfsmount_t *hfsmp;
        cnode_t *cp;
        filefork_t *ffp;
        u_int32_t temperature;

        hfsmp = VTOHFS(vp);
        if (hfsmp->hfc_stage != HFC_RECORDING)
                return (0);

        if ((!vnode_isreg(vp) && !vnode_islnk(vp)) || vnode_issystem(vp)) {
                return (0);
        }
        /* Skip resource forks for now. */
        if (VNODE_IS_RSRC(vp)) {
                return (0);
        }
        if ((hotdata = (hotfile_data_t *)hfsmp->hfc_recdata) == NULL) {
                return (0);
        }
        ffp = VTOF(vp);
        cp = VTOC(vp);

        if ((ffp->ff_bytesread == 0) ||
            (ffp->ff_blocks == 0) ||
            (ffp->ff_blocks > hotdata->maxblocks) ||
            (cp->c_flag & (C_DELETED | C_NOEXISTS)) ||
            (cp->c_flags & UF_NODUMP) ||
            (cp->c_atime < hfsmp->hfc_timebase)) {
                return (0);
        }

        temperature = ffp->ff_bytesread / ffp->ff_size;
        if (temperature < hotdata->threshold) {
                return (0);
        }
        /*
         * If there is room or this file is hotter than
         * the coldest one then add it to the list.
         *
         */
        if ((hotdata->activefiles < hfsmp->hfc_maxfiles) ||
            (hotdata->coldest == NULL) ||
            (temperature > hotdata->coldest->temperature)) {
                ++hotdata->refcount;
                entry = hf_getnewentry(hotdata);
                entry->temperature = temperature;
                entry->fileid = cp->c_fileid;
                entry->blocks = ffp->ff_blocks;
                hf_insert(hotdata, entry);
                --hotdata->refcount;
        }

        return (0);
}

/*
 * Remove a hot file from the recording list.
 *
 * This can happen when a hot file becomes
 * an active vnode (active hot files are
 * not kept in the recording list until the
 * end of the recording period).
 *
 * Note: the cnode is locked on entry.
 */
__private_extern__
int
hfs_removehotfile(struct vnode *vp)
{
        hotfile_data_t *hotdata;
        hfsmount_t *hfsmp;
        cnode_t *cp;
        filefork_t *ffp;
        u_int32_t temperature;

        hfsmp = VTOHFS(vp);
        if (hfsmp->hfc_stage != HFC_RECORDING)
                return (0);

        if ((!vnode_isreg(vp) && !vnode_islnk(vp)) || vnode_issystem(vp)) {
                return (0);
        }

        ffp = VTOF(vp);
        cp = VTOC(vp);

        if ((ffp->ff_bytesread == 0) || (ffp->ff_blocks == 0) ||
            (cp->c_atime < hfsmp->hfc_timebase)) {
                return (0);
        }

        lck_mtx_lock(&hfsmp->hfc_mutex);
        if (hfsmp->hfc_stage != HFC_RECORDING)
                goto out;
        if ((hotdata = (hotfile_data_t *)hfsmp->hfc_recdata) == NULL)
                goto out;

        temperature = ffp->ff_bytesread / ffp->ff_size;
        if (temperature < hotdata->threshold)
                goto out;

        if (hotdata->coldest && (temperature >= hotdata->coldest->temperature)) {
                ++hotdata->refcount;
                hf_delete(hotdata, VTOC(vp)->c_fileid, temperature);
                --hotdata->refcount;
        }
out:
        lck_mtx_unlock(&hfsmp->hfc_mutex);
        return (0);
}


/*
 *========================================================================
 *                     HOT FILE MAINTENANCE ROUTINES
 *========================================================================
 */

static int
hotfiles_collect_callback(struct vnode *vp, __unused void *cargs)
{
        if ((vnode_isreg(vp) || vnode_islnk(vp)) && !vnode_issystem(vp))
                (void) hfs_addhotfile_internal(vp);

        return (VNODE_RETURNED);
}

/*
 * Add all active hot files to the recording list.
 */
static int
hotfiles_collect(struct hfsmount *hfsmp)
{
        struct mount *mp = HFSTOVFS(hfsmp);

        if (vfs_busy(mp, LK_NOWAIT))
                return (0);

        /*
         * hotfiles_collect_callback will be called for each vnode
         * hung off of this mount point
         * the vnode will be
         * properly referenced and unreferenced around the callback
         */
        vnode_iterate(mp, 0, hotfiles_collect_callback, (void *)NULL);

        vfs_unbusy(mp);

        return (0);
}


/*
 * Update the data of a btree record
 * This is called from within BTUpdateRecord.
 */
static int
update_callback(const HotFileKey *key, u_int32_t *data, u_int32_t *state)
{
        if (key->temperature == HFC_LOOKUPTAG)
                *data = *state;
        return (0);
}

/*
 * Identify files already in hot area.
 */
static int
hotfiles_refine(struct hfsmount *hfsmp)
{
        BTreeIterator * iterator;
        struct mount *mp;
        filefork_t * filefork;
        hotfilelist_t  *listp;
        FSBufferDescriptor  record;
        HotFileKey * key;
        u_int32_t  data;
        int  i;
        int  error = 0;


        if ((listp = (hotfilelist_t  *)hfsmp->hfc_recdata) == NULL)
                return (0);     

        mp = HFSTOVFS(hfsmp);

        MALLOC(iterator, BTreeIterator *, sizeof(*iterator), M_TEMP, M_WAITOK);
        bzero(iterator, sizeof(*iterator));
        key = (HotFileKey*) &iterator->key;

        record.bufferAddress = &data;
        record.itemSize = sizeof(u_int32_t);
        record.itemCount = 1;

        if (hfs_start_transaction(hfsmp) != 0) {
            error = EINVAL;
            goto out;
        } 
        if (hfs_lock(VTOC(hfsmp->hfc_filevp), HFS_EXCLUSIVE_LOCK) != 0) {
                error = EPERM;
                goto out;
        }
        filefork = VTOF(hfsmp->hfc_filevp);

        for (i = 0; i < listp->hfl_count; ++i) {
                /*
                 * Check if entry (thread) is already in hot area.
                 */
                key->keyLength = HFC_KEYLENGTH;
                key->temperature = HFC_LOOKUPTAG;
                key->fileID = listp->hfl_hotfile[i].hf_fileid;
                key->forkType = 0;
                (void) BTInvalidateHint(iterator);
                if (BTSearchRecord(filefork, iterator, &record, NULL, iterator) != 0) {
                        continue;  /* not in hot area, so skip */
                }

                /*
                 * Update thread entry with latest temperature.
                 */
                error = BTUpdateRecord(filefork, iterator,
                                (IterateCallBackProcPtr)update_callback,
                                &listp->hfl_hotfile[i].hf_temperature);
                if (error) {
                        printf("hotfiles_refine: BTUpdateRecord failed %d (file %d)\n", error, key->fileID);
                        error = MacToVFSError(error);
                //      break;
                }
                /*
                 * Re-key entry with latest temperature.
                 */
                key->keyLength = HFC_KEYLENGTH;
                key->temperature = data;
                key->fileID = listp->hfl_hotfile[i].hf_fileid;
                key->forkType = 0;
                /* Pick up record data. */
                (void) BTInvalidateHint(iterator);
                (void) BTSearchRecord(filefork, iterator, &record, NULL, iterator);
                error = BTDeleteRecord(filefork, iterator);
                if (error) {
                        printf("hotfiles_refine: BTDeleteRecord failed %d (file %d)\n", error, key->fileID);
                        error = MacToVFSError(error);
                        break;
                }
                key->keyLength = HFC_KEYLENGTH;
                key->temperature = listp->hfl_hotfile[i].hf_temperature;
                key->fileID = listp->hfl_hotfile[i].hf_fileid;
                key->forkType = 0;
                error = BTInsertRecord(filefork, iterator, &record, record.itemSize);
                if (error) {
                        printf("hotfiles_refine: BTInsertRecord failed %d (file %d)\n", error, key->fileID);
                        error = MacToVFSError(error);
                        break;
                }

                /*
                 * Invalidate this entry in the list.
                 */
                listp->hfl_hotfile[i].hf_temperature = 0;
                listp->hfl_totalblocks -= listp->hfl_hotfile[i].hf_blocks;
                
        } /* end for */

        (void) BTFlushPath(filefork);
        hfs_unlock(VTOC(hfsmp->hfc_filevp));

        hfs_end_transaction(hfsmp);
out:
        FREE(iterator, M_TEMP); 
        return (error);
}

/*
 * Move new hot files into hot area.
 *
 * Requires that the hfc_mutex be held.
 */
static int
hotfiles_adopt(struct hfsmount *hfsmp)
{
        BTreeIterator * iterator;
        struct vnode *vp;
        filefork_t * filefork;
        hotfilelist_t  *listp;
        FSBufferDescriptor  record;
        HotFileKey * key;
        u_int32_t  data;
        enum hfc_stage stage;
        int  fileblocks;
        int  blksmoved;
        int  i;
        int  last;
        int  error = 0;
        int  startedtrans = 0;

        if ((listp = (hotfilelist_t  *)hfsmp->hfc_recdata) == NULL)
                return (0);     

        if (hfsmp->hfc_stage != HFC_ADOPTION) {
                return (EBUSY);
        }
        if (hfs_lock(VTOC(hfsmp->hfc_filevp), HFS_EXCLUSIVE_LOCK) != 0) {
                return (EPERM);
        }

        stage = hfsmp->hfc_stage;
        hfsmp->hfc_stage = HFC_BUSY;

        blksmoved = 0;
        last = listp->hfl_next + HFC_FILESPERSYNC;
        if (last > listp->hfl_count)
                last = listp->hfl_count;

        MALLOC(iterator, BTreeIterator *, sizeof(*iterator), M_TEMP, M_WAITOK);
        bzero(iterator, sizeof(*iterator));
        key = (HotFileKey*) &iterator->key;
        key->keyLength = HFC_KEYLENGTH;

        record.bufferAddress = &data;
        record.itemSize = sizeof(u_int32_t);
        record.itemCount = 1;

        filefork = VTOF(hfsmp->hfc_filevp);

        for (i = listp->hfl_next; (i < last) && (blksmoved < HFC_BLKSPERSYNC); ++i) {
                /*
                 * Skip invalid entries (already in hot area).
                 */
                if (listp->hfl_hotfile[i].hf_temperature == 0) {
                                listp->hfl_next++;
                                continue;
                }
                /*
                 * Acquire a vnode for this file.
                 */
                error = hfs_vget(hfsmp, listp->hfl_hotfile[i].hf_fileid, &vp, 0);
                if (error) {
                        if (error == ENOENT) {
                                error = 0;
                                listp->hfl_next++;
                                continue;  /* stale entry, go to next */
                        }
                        break;
                }
                if (!vnode_isreg(vp) && !vnode_islnk(vp)) {
                        printf("hotfiles_adopt: huh, not a file %d (%d)\n", listp->hfl_hotfile[i].hf_fileid, VTOC(vp)->c_cnid);
                        hfs_unlock(VTOC(vp));
                        vnode_put(vp);
                        listp->hfl_hotfile[i].hf_temperature = 0;
                        listp->hfl_next++;
                        continue;  /* stale entry, go to next */
                }
                if (hotextents(hfsmp, &VTOF(vp)->ff_extents[0])) {
                        hfs_unlock(VTOC(vp));
                        vnode_put(vp);
                        listp->hfl_hotfile[i].hf_temperature = 0;
                        listp->hfl_next++;
                        listp->hfl_totalblocks -= listp->hfl_hotfile[i].hf_blocks;
                        continue;  /* stale entry, go to next */
                }
                fileblocks = VTOF(vp)->ff_blocks;
                if (fileblocks > hfsmp->hfs_hotfile_freeblks) {
                        hfs_unlock(VTOC(vp));
                        vnode_put(vp);
                        listp->hfl_next++;
                        listp->hfl_totalblocks -= fileblocks;
                        continue;  /* entry too big, go to next */
                }
                
                if ((blksmoved > 0) &&
                    (blksmoved + fileblocks) > HFC_BLKSPERSYNC) {
                        hfs_unlock(VTOC(vp));
                        vnode_put(vp);
                        break;  /* adopt this entry the next time around */
                }
                /* Start a new transaction. */
                if (hfs_start_transaction(hfsmp) != 0) {
                    error = EINVAL;
                    hfs_unlock(VTOC(vp));
                    vnode_put(vp);
                    break;
                }
                startedtrans = 1;

                if (VTOC(vp)->c_desc.cd_nameptr)
                        data = *(u_int32_t *)(VTOC(vp)->c_desc.cd_nameptr);
                else
                        data = 0x3f3f3f3f;

                error = hfs_relocate(vp, hfsmp->hfs_hotfile_start, kauth_cred_get(), current_proc());
                hfs_unlock(VTOC(vp));
                vnode_put(vp);
                if (error)
                        break;
                
                /* Keep hot file free space current. */
                hfsmp->hfs_hotfile_freeblks -= fileblocks;
                listp->hfl_totalblocks -= fileblocks;
                
                /* Insert hot file entry */
                key->keyLength   = HFC_KEYLENGTH;
                key->temperature = listp->hfl_hotfile[i].hf_temperature;
                key->fileID      = listp->hfl_hotfile[i].hf_fileid;
                key->forkType    = 0;

                error = BTInsertRecord(filefork, iterator, &record, record.itemSize);
                if (error) {
                        printf("hotfiles_adopt: BTInsertRecord failed %d (fileid %d)\n", error, key->fileID);
                        error = MacToVFSError(error);
                        stage = HFC_IDLE;
                        break;
                }

                /* Insert thread record */
                key->keyLength = HFC_KEYLENGTH;
                key->temperature = HFC_LOOKUPTAG;
                key->fileID = listp->hfl_hotfile[i].hf_fileid;
                key->forkType = 0;
                data = listp->hfl_hotfile[i].hf_temperature;
                error = BTInsertRecord(filefork, iterator, &record, record.itemSize);
                if (error) {
                        printf("hotfiles_adopt: BTInsertRecord failed %d (fileid %d)\n", error, key->fileID);
                        error = MacToVFSError(error);
                        stage = HFC_IDLE;
                        break;
                }
                (void) BTFlushPath(filefork);

                /* Transaction complete. */
                if (startedtrans) {
                    hfs_end_transaction(hfsmp);
                    startedtrans = 0;
                }

                blksmoved += fileblocks;
                listp->hfl_next++;
                if (listp->hfl_next >= listp->hfl_count) {
                        break;
                }
                if (hfsmp->hfs_hotfile_freeblks <= 0) {
#if HFC_VERBOSE
                        printf("hotfiles_adopt: free space exhausted (%d)\n", hfsmp->hfs_hotfile_freeblks);
#endif
                        break;
                }
        } /* end for */

#if HFC_VERBOSE
        printf("hotfiles_adopt: [%d] adopted %d blocks (%d left)\n", listp->hfl_next, blksmoved, listp->hfl_totalblocks);
#endif
        /* Finish any outstanding transactions. */
        if (startedtrans) {
                (void) BTFlushPath(filefork);
                hfs_end_transaction(hfsmp);
                startedtrans = 0;
        }
        hfs_unlock(VTOC(hfsmp->hfc_filevp));

        if ((listp->hfl_next >= listp->hfl_count) || (hfsmp->hfs_hotfile_freeblks <= 0)) {
#if HFC_VERBOSE
                printf("hotfiles_adopt: all done relocating %d files\n", listp->hfl_count);
                printf("hotfiles_adopt: %d blocks free in hot file band\n", hfsmp->hfs_hotfile_freeblks);
#endif
                stage = HFC_IDLE;
        }
        FREE(iterator, M_TEMP);

        if (stage != HFC_ADOPTION && hfsmp->hfc_filevp) {
                (void) hfc_btree_close(hfsmp, hfsmp->hfc_filevp);
                hfsmp->hfc_filevp = NULL;
        }
        hfsmp->hfc_stage = stage;
        wakeup((caddr_t)&hfsmp->hfc_stage);
        return (error);
}

/*
 * Reclaim space by evicting the coldest files.
 *
 * Requires that the hfc_mutex be held.
 */
static int
hotfiles_evict(struct hfsmount *hfsmp, struct proc *p)
{
        BTreeIterator * iterator;
        struct vnode *vp;
        HotFileKey * key;
        filefork_t * filefork;
        hotfilelist_t  *listp;
        enum hfc_stage stage;
        u_int32_t savedtemp;
        int  blksmoved;
        int  filesmoved;
        int  fileblocks;
        int  error = 0;
        int  startedtrans = 0;
        int  bt_op;

        if (hfsmp->hfc_stage != HFC_EVICTION) {
                return (EBUSY);
        }

        if ((listp = (hotfilelist_t  *)hfsmp->hfc_recdata) == NULL)
                return (0);     

        if (hfs_lock(VTOC(hfsmp->hfc_filevp), HFS_EXCLUSIVE_LOCK) != 0) {
                return (EPERM);
        }

        stage = hfsmp->hfc_stage;
        hfsmp->hfc_stage = HFC_BUSY;

        filesmoved = blksmoved = 0;
        bt_op = kBTreeFirstRecord;

        MALLOC(iterator, BTreeIterator *, sizeof(*iterator), M_TEMP, M_WAITOK);
        bzero(iterator, sizeof(*iterator));
        key = (HotFileKey*) &iterator->key;

        filefork = VTOF(hfsmp->hfc_filevp);

        while (listp->hfl_reclaimblks > 0 &&
               blksmoved < HFC_BLKSPERSYNC &&
               filesmoved < HFC_FILESPERSYNC) {

                /*
                 * Obtain the first record (ie the coldest one).
                 */
                if (BTIterateRecord(filefork, bt_op, iterator, NULL, NULL) != 0) {
#if HFC_VERBOSE
                        printf("hotfiles_evict: no more records\n");
#endif
                        error = 0;
                        stage = HFC_ADOPTION;
                        break;
                }
                if (key->keyLength != HFC_KEYLENGTH) {
                        printf("hotfiles_evict: invalid key length %d\n", key->keyLength);
                        error = EFTYPE;
                        break;
                }               
                if (key->temperature == HFC_LOOKUPTAG) {
#if HFC_VERBOSE
                        printf("hotfiles_evict: ran into thread records\n");
#endif
                        error = 0;
                        stage = HFC_ADOPTION;
                        break;
                }
                /*
                 * Aquire the vnode for this file.
                 */
                error = hfs_vget(hfsmp, key->fileID, &vp, 0);

                /* Start a new transaction. */
                if (hfs_start_transaction(hfsmp) != 0) {
                    if (error == 0) {
                        hfs_unlock(VTOC(vp));
                        vnode_put(vp);
                    }
                    error = EINVAL;
                    break;
                }
                startedtrans = 1;

                if (error) {
                        if (error == ENOENT) {
                                goto delete;  /* stale entry, go to next */
                        } else {
                                printf("hotfiles_evict: err %d getting file %d\n",
                                       error, key->fileID);
                        }
                        break;
                }
                if (!vnode_isreg(vp) && !vnode_islnk(vp)) {
                        printf("hotfiles_evict: huh, not a file %d\n", key->fileID);
                        hfs_unlock(VTOC(vp));
                        vnode_put(vp);
                        goto delete;  /* invalid entry, go to next */
                }
                fileblocks = VTOF(vp)->ff_blocks;
                if ((blksmoved > 0) &&
                    (blksmoved + fileblocks) > HFC_BLKSPERSYNC) {
                        hfs_unlock(VTOC(vp));
                        vnode_put(vp);
                        break;
                }
                /*
                 * Make sure file is in the hot area.
                 */
                if (!hotextents(hfsmp, &VTOF(vp)->ff_extents[0])) {
#if HFC_VERBOSE
                        printf("hotfiles_evict: file %d isn't hot!\n", key->fileID);
#endif
                        hfs_unlock(VTOC(vp));
                        vnode_put(vp);
                        goto delete;  /* stale entry, go to next */
                }
                
                /*
                 * Relocate file out of hot area.
                 */
                error = hfs_relocate(vp, HFSTOVCB(hfsmp)->nextAllocation, proc_ucred(p), p);
                if (error) {
                        printf("hotfiles_evict: err %d relocating file %d\n", error, key->fileID);
                        hfs_unlock(VTOC(vp));
                        vnode_put(vp);
                        bt_op = kBTreeNextRecord;
                        goto next;  /* go to next */
                }

                //
                // We do not believe that this call to hfs_fsync() is
                // necessary and it causes a journal transaction
                // deadlock so we are removing it.
                //
                // (void) hfs_fsync(vp, MNT_WAIT, 0, p);

                hfs_unlock(VTOC(vp));
                vnode_put(vp);

                hfsmp->hfs_hotfile_freeblks += fileblocks;
                listp->hfl_reclaimblks -= fileblocks;
                if (listp->hfl_reclaimblks < 0)
                        listp->hfl_reclaimblks = 0;
                blksmoved += fileblocks;
                filesmoved++;
delete:
                error = BTDeleteRecord(filefork, iterator);
                if (error) {
                        error = MacToVFSError(error);
                        break;
                }
                savedtemp = key->temperature;
                key->temperature = HFC_LOOKUPTAG;
                error = BTDeleteRecord(filefork, iterator);
                if (error) {
                        error = MacToVFSError(error);
                        break;
                }
                key->temperature = savedtemp;
next:
                (void) BTFlushPath(filefork);

                /* Transaction complete. */
                if (startedtrans) {
                        hfs_end_transaction(hfsmp);
                        startedtrans = 0;
                }

        } /* end while */

#if HFC_VERBOSE
        printf("hotfiles_evict: moved %d files (%d blks, %d to go)\n", filesmoved, blksmoved, listp->hfl_reclaimblks);
#endif
        /* Finish any outstanding transactions. */
        if (startedtrans) {
                (void) BTFlushPath(filefork);
                hfs_end_transaction(hfsmp);
                startedtrans = 0;
        }
        hfs_unlock(VTOC(hfsmp->hfc_filevp));

        /*
         * Move to next stage when finished.
         */
        if (listp->hfl_reclaimblks <= 0) {
                stage = HFC_ADOPTION;
#if HFC_VERBOSE
                printf("hotfiles_evict: %d blocks free in hot file band\n", hfsmp->hfs_hotfile_freeblks);
#endif
        }
        FREE(iterator, M_TEMP); 
        hfsmp->hfc_stage = stage;
        wakeup((caddr_t)&hfsmp->hfc_stage);
        return (error);
}

/*
 * Age the existing records in the hot files b-tree.
 */
static int
hotfiles_age(struct hfsmount *hfsmp)
{
        BTreeInfoRec  btinfo;
        BTreeIterator * iterator;
        BTreeIterator * prev_iterator;
        FSBufferDescriptor  record;
        FSBufferDescriptor  prev_record;
        HotFileKey * key;
        HotFileKey * prev_key;
        filefork_t * filefork;
        u_int32_t  data;
        u_int32_t  prev_data;
        u_int32_t  newtemp;
        int  error;
        int  i;
        int  numrecs;
        int  aged = 0;
        u_int16_t  reclen;


        MALLOC(iterator, BTreeIterator *, 2 * sizeof(*iterator), M_TEMP, M_WAITOK);
        bzero(iterator, 2 * sizeof(*iterator));
        key = (HotFileKey*) &iterator->key;

        prev_iterator = &iterator[1];
        prev_key = (HotFileKey*) &prev_iterator->key;

        record.bufferAddress = &data;
        record.itemSize = sizeof(data);
        record.itemCount = 1;
        prev_record.bufferAddress = &prev_data;
        prev_record.itemSize = sizeof(prev_data);
        prev_record.itemCount = 1;

        /*
         * Capture b-tree changes inside a transaction
         */
        if (hfs_start_transaction(hfsmp) != 0) {
            error = EINVAL;
            goto out2;
        } 
        if (hfs_lock(VTOC(hfsmp->hfc_filevp), HFS_EXCLUSIVE_LOCK) != 0) {
                error = EPERM;
                goto out1;
        }
        filefork = VTOF(hfsmp->hfc_filevp);

        error = BTGetInformation(filefork, 0, &btinfo);
        if (error) {
                error = MacToVFSError(error);
                goto out;
        }
        if (btinfo.numRecords < 2) {
                error = 0;
                goto out;
        }
        
        /* Only want 1st half of leaf records */
        numrecs = (btinfo.numRecords /= 2) - 1;

        error = BTIterateRecord(filefork, kBTreeFirstRecord, iterator, &record, &reclen);
        if (error) {
                printf("hfs_agehotfiles: BTIterateRecord: %d\n", error);
                error = MacToVFSError(error);
                goto out;
        }
        bcopy(iterator, prev_iterator, sizeof(BTreeIterator));
        prev_data = data;

        for (i = 0; i < numrecs; ++i) {
                error = BTIterateRecord(filefork, kBTreeNextRecord, iterator, &record, &reclen);
                if (error == 0) {
                        if (key->temperature < prev_key->temperature) {
                                printf("hfs_agehotfiles: out of order keys!\n");
                                error = EFTYPE;
                                break;
                        }
                        if (reclen != sizeof(data)) {
                                printf("hfs_agehotfiles: invalid record length %d\n", reclen);
                                error = EFTYPE;
                                break;
                        }
                        if (key->keyLength != HFC_KEYLENGTH) {
                                printf("hfs_agehotfiles: invalid key length %d\n", key->keyLength);
                                error = EFTYPE;
                                break;
                        }
                } else if ((error == fsBTEndOfIterationErr || error == fsBTRecordNotFoundErr) &&
                    (i == (numrecs - 1))) {
                        error = 0;
                } else if (error) {
                        printf("hfs_agehotfiles: %d of %d BTIterateRecord: %d\n", i, numrecs, error);
                        error = MacToVFSError(error);
                        break;
                }
                if (prev_key->temperature == HFC_LOOKUPTAG) {
#if HFC_VERBOSE 
                        printf("hfs_agehotfiles: ran into thread record\n");
#endif
                        error = 0;
                        break;
                }
                error = BTDeleteRecord(filefork, prev_iterator);
                if (error) {
                        printf("hfs_agehotfiles: BTDeleteRecord failed %d (file %d)\n", error, prev_key->fileID);
                        error = MacToVFSError(error);
                        break;
                }
                
                /* Age by halving the temperature (floor = 4) */
                newtemp = MAX(prev_key->temperature >> 1, 4);
                prev_key->temperature = newtemp;
        
                error = BTInsertRecord(filefork, prev_iterator, &prev_record, prev_record.itemSize);
                if (error) {
                        printf("hfs_agehotfiles: BTInsertRecord failed %d (file %d)\n", error, prev_key->fileID);
                        error = MacToVFSError(error);
                        break;
                }
                ++aged;
                /*
                 * Update thread entry with latest temperature.
                 */
                prev_key->temperature = HFC_LOOKUPTAG;
                error = BTUpdateRecord(filefork, prev_iterator,
                                (IterateCallBackProcPtr)update_callback,
                                &newtemp);
                if (error) {
                        printf("hfs_agehotfiles: %d of %d BTUpdateRecord failed %d (file %d, %d)\n",
                                i, numrecs, error, prev_key->fileID, newtemp);
                        error = MacToVFSError(error);
                //      break;
                }

                bcopy(iterator, prev_iterator, sizeof(BTreeIterator));
                prev_data = data;

        } /* end for */

#if HFC_VERBOSE 
        if (error == 0)
                printf("hfs_agehotfiles: aged %d records out of %d\n", aged, btinfo.numRecords);
#endif
        (void) BTFlushPath(filefork);
out:
        hfs_unlock(VTOC(hfsmp->hfc_filevp));
out1:
        hfs_end_transaction(hfsmp);
out2:
        FREE(iterator, M_TEMP); 
        return (error);
}

/*
 * Return true if any blocks (or all blocks if all is true)
 * are contained in the hot file region.
 */
static int
hotextents(struct hfsmount *hfsmp, HFSPlusExtentDescriptor * extents)
{
        u_int32_t  b1, b2;
        int  i;
        int  inside = 0;

        for (i = 0; i < kHFSPlusExtentDensity; ++i) {
                b1 = extents[i].startBlock;
                if (b1 == 0)
                        break;
                b2 = b1 + extents[i].blockCount - 1;
                if ((b1 >= hfsmp->hfs_hotfile_start &&
                     b2 <= hfsmp->hfs_hotfile_end) ||
                    (b1 < hfsmp->hfs_hotfile_end && 
                     b2 > hfsmp->hfs_hotfile_end)) {
                        inside = 1;
                        break;
                }
        }
        return (inside);
}


/*
 *========================================================================
 *                       HOT FILE B-TREE ROUTINES
 *========================================================================
 */

/*
 * Open the hot files b-tree for writing.
 *
 * On successful exit the vnode has a reference but not an iocount.
 */
static int
hfc_btree_open(struct hfsmount *hfsmp, struct vnode **vpp)
{
        struct proc *p;
        struct vnode *vp;
        struct cat_desc  cdesc;
        struct cat_attr  cattr;
        struct cat_fork  cfork;
        static char filename[] = HFC_FILENAME;
        int  error;
        int  retry = 0;
        int lockflags;

        *vpp = NULL;
        p = current_proc();

        bzero(&cdesc, sizeof(cdesc));
        cdesc.cd_parentcnid = kRootDirID;
        cdesc.cd_nameptr = filename;
        cdesc.cd_namelen = strlen(filename);

        lockflags = hfs_systemfile_lock(hfsmp, SFL_CATALOG, HFS_SHARED_LOCK);

        error = cat_lookup(hfsmp, &cdesc, 0, &cdesc, &cattr, &cfork, NULL);

        hfs_systemfile_unlock(hfsmp, lockflags);

        if (error) {
                printf("hfc_btree_open: cat_lookup error %d\n", error);
                return (error);
        }
again:
        cdesc.cd_flags |= CD_ISMETA;
        error = hfs_getnewvnode(hfsmp, NULL, NULL, &cdesc, 0, &cattr, &cfork, &vp);
        if (error) {
                printf("hfc_btree_open: hfs_getnewvnode error %d\n", error);
                cat_releasedesc(&cdesc);
                return (error);
        }
        if (!vnode_issystem(vp)) {
#if HFC_VERBOSE
                printf("hfc_btree_open: file has UBC, try again\n");
#endif
                hfs_unlock(VTOC(vp));
                vnode_recycle(vp);
                vnode_put(vp);
                if (retry++ == 0)
                        goto again;
                else
                        return (EBUSY);
        }

        /* Open the B-tree file for writing... */
        error = BTOpenPath(VTOF(vp), (KeyCompareProcPtr) hfc_comparekeys);      
        if (error) {
                printf("hfc_btree_open: BTOpenPath error %d\n", error);
                error = MacToVFSError(error);
        }

        hfs_unlock(VTOC(vp));
        if (error == 0) {
                *vpp = vp;
                vnode_ref(vp);  /* keep a reference while its open */
        }
        vnode_put(vp);

        if (!vnode_issystem(vp))
                panic("hfc_btree_open: not a system file (vp = 0x%08x)", vp);

        if (UBCINFOEXISTS(vp))
                panic("hfc_btree_open: has UBCInfo (vp = 0x%08x)", vp);

        return (error);
}

/*
 * Close the hot files b-tree.
 *
 * On entry the vnode has a reference.
 */
static int
hfc_btree_close(struct hfsmount *hfsmp, struct vnode *vp)
{
        struct proc *p = current_proc();
        int  error = 0;


        if (hfsmp->jnl) {
            journal_flush(hfsmp->jnl);
        }

        if (vnode_get(vp) == 0) {
                error = hfs_lock(VTOC(vp), HFS_EXCLUSIVE_LOCK);
                if (error == 0) {
                        (void) hfs_fsync(vp, MNT_WAIT, 0, p);
                        error = BTClosePath(VTOF(vp));
                        hfs_unlock(VTOC(vp));
                }
                vnode_rele(vp);
                vnode_recycle(vp);
                vnode_put(vp);
        }
        
        return (error);
}

/*
 *  Create a hot files btree file.
 *
 */
static int
hfc_btree_create(struct hfsmount *hfsmp, int nodesize, int entries)
{
        struct vnode *dvp = NULL;
        struct vnode *vp = NULL;
        struct cnode *cp = NULL;
        struct vfs_context context;
        struct vnode_attr va;
        struct componentname cname;
        static char filename[] = HFC_FILENAME;
        int  error;

        context.vc_proc = current_proc();
        context.vc_ucred = kauth_cred_get();

        if (hfsmp->hfc_filevp)
                panic("hfc_btree_create: hfc_filevp exists (vp = 0x%08x)", hfsmp->hfc_filevp);

        error = VFS_ROOT(HFSTOVFS(hfsmp), &dvp, &context);
        if (error) {
                return (error);
        }
        cname.cn_nameiop = CREATE;
        cname.cn_flags = ISLASTCN;
        cname.cn_context = &context;
        cname.cn_pnbuf = filename;
        cname.cn_pnlen = sizeof(filename);
        cname.cn_nameptr = filename;
        cname.cn_namelen = strlen(filename);
        cname.cn_hash = 0;
        cname.cn_consume = 0;

        VATTR_INIT(&va);
        VATTR_SET(&va, va_type, VREG);
        VATTR_SET(&va, va_mode, S_IFREG | S_IRUSR | S_IWUSR);
        VATTR_SET(&va, va_uid, 0);
        VATTR_SET(&va, va_gid, 0);

        /* call ourselves directly, ignore the higher-level VFS file creation code */
        error = VNOP_CREATE(dvp, &vp, &cname, &va, &context);
        if (error) {
                printf("HFS: error %d creating HFBT on %s\n", error, HFSTOVCB(hfsmp)->vcbVN);
                goto out;
        }
        if (dvp) {
                vnode_put(dvp);
                dvp = NULL;
        }
        if ((error = hfs_lock(VTOC(vp), HFS_EXCLUSIVE_LOCK))) {
                goto out;
        }
        cp = VTOC(vp);

        /* Don't use non-regular files or files with links. */
        if (!vnode_isreg(vp) || cp->c_nlink != 1) {
                error = EFTYPE;
                goto out;
        }

        printf("HFS: created HFBT on %s\n", HFSTOVCB(hfsmp)->vcbVN);

        if (VTOF(vp)->ff_size < (u_int64_t)nodesize) {
                caddr_t  buffer;
                u_int16_t *index;
                u_int16_t  offset;
                BTNodeDescriptor  *ndp;
                BTHeaderRec  *bthp;
                HotFilesInfo *hotfileinfo;
                int  nodecnt;
                int  filesize;
                int  entirespernode;

                /*
                 * Mark it invisible (truncate will pull these changes).
                 */
                ((FndrFileInfo *)&cp->c_finderinfo[0])->fdFlags |=
                        SWAP_BE16 (kIsInvisible + kNameLocked);

                if (kmem_alloc(kernel_map, (vm_offset_t *)&buffer, nodesize)) {
                        error = ENOMEM;
                        goto out;
                }       
                bzero(buffer, nodesize);
                index = (int16_t *)buffer;
        
                entirespernode = (nodesize - sizeof(BTNodeDescriptor) - 2) /
                                 (sizeof(HotFileKey) + 6);
                nodecnt = 2 + howmany(entries * 2, entirespernode);
                nodecnt = roundup(nodecnt, 8);
                filesize = nodecnt * nodesize;
        
                /* FILL IN THE NODE DESCRIPTOR:  */
                ndp = (BTNodeDescriptor *)buffer;
                ndp->kind = kBTHeaderNode;
                ndp->numRecords = SWAP_BE16 (3);
                offset = sizeof(BTNodeDescriptor);
                index[(nodesize / 2) - 1] = SWAP_BE16 (offset);
        
                /* FILL IN THE HEADER RECORD:  */
                bthp = (BTHeaderRec *)((UInt8 *)buffer + offset);
                bthp->nodeSize     = SWAP_BE16 (nodesize);
                bthp->totalNodes   = SWAP_BE32 (filesize / nodesize);
                bthp->freeNodes    = SWAP_BE32 (nodecnt - 1);
                bthp->clumpSize    = SWAP_BE32 (filesize);
                bthp->btreeType    = kUserBTreeType; /* non-metadata */
                bthp->attributes  |= SWAP_BE32 (kBTBigKeysMask);
                bthp->maxKeyLength = SWAP_BE16 (HFC_KEYLENGTH);
                offset += sizeof(BTHeaderRec);
                index[(nodesize / 2) - 2] = SWAP_BE16 (offset);
        
                /* FILL IN THE USER RECORD:  */
                hotfileinfo = (HotFilesInfo *)((UInt8 *)buffer + offset);
                hotfileinfo->magic       = SWAP_BE32 (HFC_MAGIC);
                hotfileinfo->version     = SWAP_BE32 (HFC_VERSION);
                hotfileinfo->duration    = SWAP_BE32 (HFC_DEFAULT_DURATION);
                hotfileinfo->timebase    = 0;
                hotfileinfo->timeleft    = 0;
                hotfileinfo->threshold   = SWAP_BE32 (HFC_MINIMUM_TEMPERATURE);
                hotfileinfo->maxfileblks = SWAP_BE32 (HFC_MAXIMUM_FILESIZE / HFSTOVCB(hfsmp)->blockSize);
                hotfileinfo->maxfilecnt  = SWAP_BE32 (HFC_DEFAULT_FILE_COUNT);
                strcpy(hotfileinfo->tag, hfc_tag);
                offset += kBTreeHeaderUserBytes;
                index[(nodesize / 2) - 3] = SWAP_BE16 (offset);
        
                /* FILL IN THE MAP RECORD (only one node in use). */
                *((u_int8_t *)buffer + offset) = 0x80;
                offset += nodesize - sizeof(BTNodeDescriptor) - sizeof(BTHeaderRec)
                                   - kBTreeHeaderUserBytes - (4 * sizeof(int16_t));
                index[(nodesize / 2) - 4] = SWAP_BE16 (offset);

                vnode_setnoflush(vp);
                error = hfs_truncate(vp, (off_t)filesize, IO_NDELAY, 0, &context);
                if (error) {
                        printf("HFS: error %d growing HFBT on %s\n", error, HFSTOVCB(hfsmp)->vcbVN);
                        goto out;
                }
                cp->c_flag |= C_ZFWANTSYNC;
                cp->c_zftimeout = 1;
                
                if (error == 0) {
                        struct vnop_write_args args;
                        uio_t auio;

                        auio = uio_create(1, 0, UIO_SYSSPACE32, UIO_WRITE);
                        uio_addiov(auio, (uintptr_t)buffer, nodesize);

                        args.a_desc = &vnop_write_desc;
                        args.a_vp = vp;
                        args.a_uio = auio;
                        args.a_ioflag = 0;
                        args.a_context = &context;

                        hfs_unlock(cp);
                        cp = NULL;

                        error = hfs_vnop_write(&args);
                        if (error)
                                printf("HFS: error %d writing HFBT on %s\n", error, HFSTOVCB(hfsmp)->vcbVN);

                        uio_free(auio);
                }
                kmem_free(kernel_map, (vm_offset_t)buffer, nodesize);
        }
out:
        if (dvp) {
                vnode_put(dvp);
        }
        if (vp) {
                if (cp)
                        hfs_unlock(cp);
                vnode_recycle(vp);
                vnode_put(vp);
        }
        return (error);
}

/*
 * Compare two hot file b-tree keys.
 *
 * Result:   +n  search key > trial key
 *            0  search key = trial key
 *           -n  search key < trial key
 */
static int
hfc_comparekeys(HotFileKey *searchKey, HotFileKey *trialKey)
{
        /*
         * Compared temperatures first.
         */
        if (searchKey->temperature == trialKey->temperature) {
                /*
                 * Temperatures are equal so compare file ids.
                 */
                if (searchKey->fileID == trialKey->fileID) {
                        /*
                         * File ids are equal so compare fork types.
                         */
                        if (searchKey->forkType == trialKey->forkType) {
                                return (0);
                        } else if (searchKey->forkType > trialKey->forkType) {
                                return (1);
                        }
                } else if (searchKey->fileID > trialKey->fileID) {
                        return (1);
                }
        } else if (searchKey->temperature > trialKey->temperature) {
                return (1);
        }
        
        return (-1);
}


/*
 *========================================================================
 *               HOT FILE DATA COLLECTING ROUTINES
 *========================================================================
 */

/*
 * Lookup a hot file entry in the tree.
 */
#if HFC_DEBUG
static hotfile_entry_t *
hf_lookup(hotfile_data_t *hotdata, u_int32_t fileid, u_int32_t temperature)
{
        hotfile_entry_t *entry = hotdata->rootentry;

        while (entry &&
               entry->temperature != temperature &&
               entry->fileid != fileid) {

                if (temperature > entry->temperature)
                        entry = entry->right;
                else if (temperature < entry->temperature)
                        entry = entry->left;
                else if (fileid > entry->fileid)
                        entry = entry->right;
                else
                        entry = entry->left;
        }
        return (entry);
}
#endif

/*
 * Insert a hot file entry into the tree.
 */
static void
hf_insert(hotfile_data_t *hotdata, hotfile_entry_t *newentry) 
{
        hotfile_entry_t *entry = hotdata->rootentry;
        u_int32_t fileid = newentry->fileid;
        u_int32_t temperature = newentry->temperature;

        if (entry == NULL) {
                hotdata->rootentry = newentry;
                hotdata->coldest = newentry;
                hotdata->activefiles++;
                return;
        }

        while (entry) {
                if (temperature > entry->temperature) {
                        if (entry->right)
                                entry = entry->right;
                        else {
                                entry->right = newentry;
                                break;
                        }
                } else if (temperature < entry->temperature) {
                        if (entry->left) 
                                entry = entry->left;
                        else {
                                entry->left = newentry;
                                break;
                        }
                } else if (fileid > entry->fileid) { 
                        if (entry->right)

                                entry = entry->right;
                        else {
                                if (entry->fileid != fileid)
                                        entry->right = newentry;
                                break;
                        }
                } else { 
                        if (entry->left) 
                                entry = entry->left;
                        else {
                                if (entry->fileid != fileid)
                                        entry->left = newentry;
                                break;
                        }
                }
        }

        hotdata->activefiles++;
}

/*
 * Find the coldest entry in the tree.
 */
static hotfile_entry_t *
hf_coldest(hotfile_data_t *hotdata)
{
        hotfile_entry_t *entry = hotdata->rootentry;

        if (entry) {
                while (entry->left)
                        entry = entry->left;
        }
        return (entry);
}

/*
 * Find the hottest entry in the tree.
 */
static hotfile_entry_t *
hf_hottest(hotfile_data_t *hotdata)
{
        hotfile_entry_t *entry = hotdata->rootentry;

        if (entry) {
                while (entry->right)
                        entry = entry->right;
        }
        return (entry);
}

/*
 * Delete a hot file entry from the tree.
 */
static void
hf_delete(hotfile_data_t *hotdata, u_int32_t fileid, u_int32_t temperature)
{
        hotfile_entry_t *entry, *parent, *next;

        parent = NULL;
        entry = hotdata->rootentry;

        while (entry &&
               entry->temperature != temperature &&
               entry->fileid != fileid) {

                parent = entry;
                if (temperature > entry->temperature)
                        entry = entry->right;
                else if (temperature < entry->temperature)
                        entry = entry->left;
                else if (fileid > entry->fileid)
                        entry = entry->right;
                else
                        entry = entry->left;
        }

        if (entry) {
                /*
                 * Reorginize the sub-trees spanning from our entry.
                 */
                if ((next = entry->right)) {
                        hotfile_entry_t *pnextl, *psub;
                        /*
                         * Tree pruning: take the left branch of the
                         * current entry and place it at the lowest
                         * left branch of the current right branch 
                         */
                        psub = next;
                        
                        /* Walk the Right/Left sub tree from current entry */
                        while ((pnextl = psub->left))
                                psub = pnextl;  
                        
                        /* Plug the old left tree to the new ->Right leftmost entry */  
                        psub->left = entry->left;
        
                } else /* only left sub-tree, simple case */ {  
                        next = entry->left;
                }
                /* 
                 * Now, plug the current entry sub tree to
                 * the good pointer of our parent entry.
                 */
                if (parent == NULL)
                        hotdata->rootentry = next;
                else if (parent->left == entry)
                        parent->left = next;
                else
                        parent->right = next;   
                
                /* Place entry back on the free-list */
                entry->left = 0;
                entry->fileid = 0;
                entry->temperature = 0;

                entry->right = hotdata->freelist; 
                hotdata->freelist = entry;              
                hotdata->activefiles--;
                
                if (hotdata->coldest == entry || hotdata->coldest == NULL) {
                        hotdata->coldest = hf_coldest(hotdata);
                }

        }
}

/*
 * Get a free hot file entry.
 */
static hotfile_entry_t *
hf_getnewentry(hotfile_data_t *hotdata)
{
        hotfile_entry_t * entry;
        
        /*
         * When the free list is empty then steal the coldest one
         */
        if (hotdata->freelist == NULL) {
                entry = hf_coldest(hotdata);
                hf_delete(hotdata, entry->fileid, entry->temperature);
        }
        entry = hotdata->freelist;
        hotdata->freelist = entry->right;
        entry->right = 0;
        
        return (entry);
}


/*
 * Generate a sorted list of hot files (hottest to coldest).
 *
 * As a side effect, every node in the hot file tree will be
 * deleted (moved to the free list).
 */
static void
hf_getsortedlist(hotfile_data_t * hotdata, hotfilelist_t *sortedlist)
{
        int i = 0;
        hotfile_entry_t *entry;
        
        while ((entry = hf_hottest(hotdata)) != NULL) {
                sortedlist->hfl_hotfile[i].hf_fileid = entry->fileid;
                sortedlist->hfl_hotfile[i].hf_temperature = entry->temperature;
                sortedlist->hfl_hotfile[i].hf_blocks = entry->blocks;
                sortedlist->hfl_totalblocks += entry->blocks;
                ++i;

                hf_delete(hotdata, entry->fileid, entry->temperature);
        }
        
        sortedlist->hfl_count = i;
        
#if HFC_VERBOSE
        printf("HFS: hf_getsortedlist returned %d entries\n", i);
#endif
}


#if HFC_DEBUG
static void
hf_maxdepth(hotfile_entry_t * root, int depth, int *maxdepth)
{
        if (root) {
                depth++;
                if (depth > *maxdepth)
                        *maxdepth = depth;
                hf_maxdepth(root->left, depth, maxdepth);
                hf_maxdepth(root->right, depth, maxdepth);
        }
}

static void
hf_printtree(hotfile_entry_t * root)
{
        if (root) {
                hf_printtree(root->left);
                printf("temperature: % 8d, fileid %d\n", root->temperature, root->fileid);
                hf_printtree(root->right);
        }
}
#endif