/*
 * Copyright 2000, International Business Machines Corporation and others.
 *$All Rights Reserved.
 * 
 * This software has been released under the terms of the IBM Public
 * License.  For details, see the LICENSE file in the top-level source
 * directory or online at http://www.openafs.org/dl/license10.html
 */

/*
 * Implements:
 */
#include <afsconfig.h>
#include "afs/param.h"

RCSID
    ("$Header: /cvs/openafs/src/afs/afs_dcache.c,v 1.42 2004/05/08 04:33:07 shadow Exp $");

#include "afs/sysincludes.h"	/*Standard vendor system headers */
#include "afsincludes.h"	/*AFS-based standard headers */
#include "afs/afs_stats.h"	/* statistics */
#include "afs/afs_cbqueue.h"
#include "afs/afs_osidnlc.h"

/* Forward declarations. */
static void afs_GetDownD(int anumber, int *aneedSpace);
static void afs_FreeDiscardedDCache(void);
static void afs_DiscardDCache(struct dcache *);
static void afs_FreeDCache(struct dcache *);

/*
 * --------------------- Exported definitions ---------------------
 */
afs_lock_t afs_xdcache;		/*Lock: alloc new disk cache entries */
afs_int32 afs_freeDCList;	/*Free list for disk cache entries */
afs_int32 afs_freeDCCount;	/*Count of elts in freeDCList */
afs_int32 afs_discardDCList;	/*Discarded disk cache entries */
afs_int32 afs_discardDCCount;	/*Count of elts in discardDCList */
struct dcache *afs_freeDSList;	/*Free list for disk slots */
struct dcache *afs_Initial_freeDSList;	/*Initial list for above */
ino_t cacheInode;		/*Inode for CacheItems file */
struct osi_file *afs_cacheInodep = 0;	/* file for CacheItems inode */
struct afs_q afs_DLRU;		/*dcache LRU */
afs_int32 afs_dhashsize = 1024;
afs_int32 *afs_dvhashTbl;	/*Data cache hash table */
afs_int32 *afs_dchashTbl;	/*Data cache hash table */
afs_int32 *afs_dvnextTbl;	/*Dcache hash table links */
afs_int32 *afs_dcnextTbl;	/*Dcache hash table links */
struct dcache **afs_indexTable;	/*Pointers to dcache entries */
afs_hyper_t *afs_indexTimes;	/*Dcache entry Access times */
afs_int32 *afs_indexUnique;	/*dcache entry Fid.Unique */
unsigned char *afs_indexFlags;	/*(only one) Is there data there? */
afs_hyper_t afs_indexCounter;	/*Fake time for marking index
				 * entries */
afs_int32 afs_cacheFiles = 0;	/*Size of afs_indexTable */
afs_int32 afs_cacheBlocks;	/*1K blocks in cache */
afs_int32 afs_cacheStats;	/*Stat entries in cache */
afs_int32 afs_blocksUsed;	/*Number of blocks in use */
afs_int32 afs_blocksDiscarded;	/*Blocks freed but not truncated */
afs_int32 afs_fsfragsize = 1023;	/*Underlying Filesystem minimum unit 
					 *of disk allocation usually 1K
					 *this value is (truefrag -1 ) to
					 *save a bunch of subtracts... */
#ifdef AFS_64BIT_CLIENT
#ifdef AFS_VM_RDWR_ENV
afs_size_t afs_vmMappingEnd;	/* for large files (>= 2GB) the VM
				 * mapping an 32bit addressing machines
				 * can only be used below the 2 GB
				 * line. From this point upwards we
				 * must do direct I/O into the cache
				 * files. The value should be on a
				 * chunk boundary. */
#endif /* AFS_VM_RDWR_ENV */
#endif /* AFS_64BIT_CLIENT */

/* The following is used to ensure that new dcache's aren't obtained when
 * the cache is nearly full.
 */
int afs_WaitForCacheDrain = 0;
int afs_TruncateDaemonRunning = 0;
int afs_CacheTooFull = 0;

afs_int32 afs_dcentries;	/* In-memory dcache entries */


int dcacheDisabled = 0;

static int afs_UFSCacheFetchProc(), afs_UFSCacheStoreProc();
struct afs_cacheOps afs_UfsCacheOps = {
    osi_UFSOpen,
    osi_UFSTruncate,
    afs_osi_Read,
    afs_osi_Write,
    osi_UFSClose,
    afs_UFSRead,
    afs_UFSWrite,
    afs_UFSCacheFetchProc,
    afs_UFSCacheStoreProc,
    afs_UFSGetDSlot,
    afs_UFSGetVolSlot,
    afs_UFSHandleLink,
};

struct afs_cacheOps afs_MemCacheOps = {
    afs_MemCacheOpen,
    afs_MemCacheTruncate,
    afs_MemReadBlk,
    afs_MemWriteBlk,
    afs_MemCacheClose,
    afs_MemRead,
    afs_MemWrite,
    afs_MemCacheFetchProc,
    afs_MemCacheStoreProc,
    afs_MemGetDSlot,
    afs_MemGetVolSlot,
    afs_MemHandleLink,
};

int cacheDiskType;		/*Type of backing disk for cache */
struct afs_cacheOps *afs_cacheType;




/*
 * afs_StoreWarn
 *
 * Description:
 *	Warn about failing to store a file.
 *
 * Parameters:
 *	acode   : Associated error code.
 *	avolume : Volume involved.
 *	aflags  : How to handle the output:
 *			aflags & 1: Print out on console
 *			aflags & 2: Print out on controlling tty
 *
 * Environment:
 *	Call this from close call when vnodeops is RCS unlocked.
 */

void
afs_StoreWarn(register afs_int32 acode, afs_int32 avolume,
	      register afs_int32 aflags)
{
    static char problem_fmt[] =
	"afs: failed to store file in volume %d (%s)\n";
    static char problem_fmt_w_error[] =
	"afs: failed to store file in volume %d (error %d)\n";
    static char netproblems[] = "network problems";
    static char partfull[] = "partition full";
    static char overquota[] = "over quota";

    AFS_STATCNT(afs_StoreWarn);
    if (acode < 0) {
	/*
	 * Network problems
	 */
	if (aflags & 1)
	    afs_warn(problem_fmt, avolume, netproblems);
	if (aflags & 2)
	    afs_warnuser(problem_fmt, avolume, netproblems);
    } else if (acode == ENOSPC) {
	/*
	 * Partition full
	 */
	if (aflags & 1)
	    afs_warn(problem_fmt, avolume, partfull);
	if (aflags & 2)
	    afs_warnuser(problem_fmt, avolume, partfull);
    } else
#ifdef	EDQUOT
	/* EDQUOT doesn't exist on solaris and won't be sent by the server.
	 * Instead ENOSPC will be sent...
	 */
    if (acode == EDQUOT) {
	/*
	 * Quota exceeded
	 */
	if (aflags & 1)
	    afs_warn(problem_fmt, avolume, overquota);
	if (aflags & 2)
	    afs_warnuser(problem_fmt, avolume, overquota);
    } else
#endif
    {
	/*
	 * Unknown error
	 */
	if (aflags & 1)
	    afs_warn(problem_fmt_w_error, avolume, acode);
	if (aflags & 2)
	    afs_warnuser(problem_fmt_w_error, avolume, acode);
    }
}				/*afs_StoreWarn */

void
afs_MaybeWakeupTruncateDaemon(void)
{
    if (!afs_CacheTooFull && afs_CacheIsTooFull()) {
	afs_CacheTooFull = 1;
	if (!afs_TruncateDaemonRunning)
	    afs_osi_Wakeup((int *)afs_CacheTruncateDaemon);
    } else if (!afs_TruncateDaemonRunning
	       && afs_blocksDiscarded > CM_MAXDISCARDEDCHUNKS) {
	afs_osi_Wakeup((int *)afs_CacheTruncateDaemon);
    }
}

/* Keep statistics on run time for afs_CacheTruncateDaemon. This is a
 * struct so we need only export one symbol for AIX.
 */
static struct CTD_stats {
    osi_timeval_t CTD_beforeSleep;
    osi_timeval_t CTD_afterSleep;
    osi_timeval_t CTD_sleepTime;
    osi_timeval_t CTD_runTime;
    int CTD_nSleeps;
} CTD_stats;

u_int afs_min_cache = 0;
void
afs_CacheTruncateDaemon(void)
{
    osi_timeval_t CTD_tmpTime;
    u_int counter;
    u_int cb_lowat;
    u_int dc_hiwat =
	(100 - CM_DCACHECOUNTFREEPCT +
	 CM_DCACHEEXTRAPCT) * afs_cacheFiles / 100;
    afs_min_cache =
	(((10 * AFS_CHUNKSIZE(0)) + afs_fsfragsize) & ~afs_fsfragsize) >> 10;

    osi_GetuTime(&CTD_stats.CTD_afterSleep);
    afs_TruncateDaemonRunning = 1;
    while (1) {
	cb_lowat = ((CM_DCACHESPACEFREEPCT - CM_DCACHEEXTRAPCT)
		    * afs_cacheBlocks) / 100;
	MObtainWriteLock(&afs_xdcache, 266);
	if (afs_CacheTooFull) {
	    int space_needed, slots_needed;
	    /* if we get woken up, we should try to clean something out */
	    for (counter = 0; counter < 10; counter++) {
		space_needed =
		    afs_blocksUsed - afs_blocksDiscarded - cb_lowat;
		slots_needed =
		    dc_hiwat - afs_freeDCCount - afs_discardDCCount;
		afs_GetDownD(slots_needed, &space_needed);
		if ((space_needed <= 0) && (slots_needed <= 0)) {
		    break;
		}
		if (afs_termState == AFSOP_STOP_TRUNCDAEMON)
		    break;
	    }
	    if (!afs_CacheIsTooFull())
		afs_CacheTooFull = 0;
	}
	MReleaseWriteLock(&afs_xdcache);

	/*
	 * This is a defensive check to try to avoid starving threads
	 * that may need the global lock so thay can help free some
	 * cache space. If this thread won't be sleeping or truncating
	 * any cache files then give up the global lock so other
	 * threads get a chance to run.
	 */
	if ((afs_termState != AFSOP_STOP_TRUNCDAEMON) && afs_CacheTooFull
	    && (!afs_blocksDiscarded || afs_WaitForCacheDrain)) {
	    afs_osi_Wait(100, 0, 0);	/* 100 milliseconds */
	}

	/*
	 * This is where we free the discarded cache elements.
	 */
	while (afs_blocksDiscarded && !afs_WaitForCacheDrain
	       && (afs_termState != AFSOP_STOP_TRUNCDAEMON)) {
	    afs_FreeDiscardedDCache();
	}

	/* See if we need to continue to run. Someone may have
	 * signalled us while we were executing.
	 */
	if (!afs_WaitForCacheDrain && !afs_CacheTooFull
	    && (afs_termState != AFSOP_STOP_TRUNCDAEMON)) {
	    /* Collect statistics on truncate daemon. */
	    CTD_stats.CTD_nSleeps++;
	    osi_GetuTime(&CTD_stats.CTD_beforeSleep);
	    afs_stats_GetDiff(CTD_tmpTime, CTD_stats.CTD_afterSleep,
			      CTD_stats.CTD_beforeSleep);
	    afs_stats_AddTo(CTD_stats.CTD_runTime, CTD_tmpTime);

	    afs_TruncateDaemonRunning = 0;
	    afs_osi_Sleep((int *)afs_CacheTruncateDaemon);
	    afs_TruncateDaemonRunning = 1;

	    osi_GetuTime(&CTD_stats.CTD_afterSleep);
	    afs_stats_GetDiff(CTD_tmpTime, CTD_stats.CTD_beforeSleep,
			      CTD_stats.CTD_afterSleep);
	    afs_stats_AddTo(CTD_stats.CTD_sleepTime, CTD_tmpTime);
	}
	if (afs_termState == AFSOP_STOP_TRUNCDAEMON) {
#ifdef AFS_AFSDB_ENV
	    afs_termState = AFSOP_STOP_AFSDB;
#else
	    afs_termState = AFSOP_STOP_RXEVENT;
#endif
	    afs_osi_Wakeup(&afs_termState);
	    break;
	}
    }
}


/*
 * afs_AdjustSize
 *
 * Description:
 * 	Make adjustment for the new size in the disk cache entry
 *
 * Major Assumptions Here:
 *      Assumes that frag size is an integral power of two, less one,
 *      and that this is a two's complement machine.  I don't
 *      know of any filesystems which violate this assumption...
 *
 * Parameters:
 *	adc	 : Ptr to dcache entry.
 *	anewsize : New size desired.
 */

void
afs_AdjustSize(register struct dcache *adc, register afs_int32 newSize)
{
    register afs_int32 oldSize;

    AFS_STATCNT(afs_AdjustSize);

    adc->dflags |= DFEntryMod;
    oldSize = ((adc->f.chunkBytes + afs_fsfragsize) ^ afs_fsfragsize) >> 10;	/* round up */
    adc->f.chunkBytes = newSize;
    if (!newSize)
	adc->validPos = 0;
    newSize = ((newSize + afs_fsfragsize) ^ afs_fsfragsize) >> 10;	/* round up */
    if (newSize > oldSize) {
	/* We're growing the file, wakeup the daemon */
	afs_MaybeWakeupTruncateDaemon();
    }
    afs_blocksUsed += (newSize - oldSize);
    afs_stats_cmperf.cacheBlocksInUse = afs_blocksUsed;	/* XXX */
}


/*
 * afs_GetDownD
 *
 * Description:
 *	This routine is responsible for moving at least one entry (but up
 *	to some number of them) from the LRU queue to the free queue.
 *
 * Parameters:
 *	anumber	   : Number of entries that should ideally be moved.
 *	aneedSpace : How much space we need (1K blocks);
 *
 * Environment:
 *	The anumber parameter is just a hint; at least one entry MUST be
 *	moved, or we'll panic.  We must be called with afs_xdcache
 *	write-locked.  We should try to satisfy both anumber and aneedspace,
 *      whichever is more demanding - need to do several things:
 *      1.  only grab up to anumber victims if aneedSpace <= 0, not
 *          the whole set of MAXATONCE.
 *      2.  dynamically choose MAXATONCE to reflect severity of
 *          demand: something like (*aneedSpace >> (logChunk - 9)) 
 *  N.B. if we're called with aneedSpace <= 0 and anumber > 0, that
 *  indicates that the cache is not properly configured/tuned or
 *  something. We should be able to automatically correct that problem.
 */

#define	MAXATONCE   16		/* max we can obtain at once */
static void
afs_GetDownD(int anumber, int *aneedSpace)
{

    struct dcache *tdc;
    struct VenusFid *afid;
    afs_int32 i, j;
    afs_hyper_t vtime;
    int skip, phase;
    register struct vcache *tvc;
    afs_uint32 victims[MAXATONCE];
    struct dcache *victimDCs[MAXATONCE];
    afs_hyper_t victimTimes[MAXATONCE];	/* youngest (largest LRU time) first */
    afs_uint32 victimPtr;	/* next free item in victim arrays */
    afs_hyper_t maxVictimTime;	/* youngest (largest LRU time) victim */
    afs_uint32 maxVictimPtr;	/* where it is */
    int discard;

    AFS_STATCNT(afs_GetDownD);
    if (CheckLock(&afs_xdcache) != -1)
	osi_Panic("getdownd nolock");
    /* decrement anumber first for all dudes in free list */
    /* SHOULD always decrement anumber first, even if aneedSpace >0, 
     * because we should try to free space even if anumber <=0 */
    if (!aneedSpace || *aneedSpace <= 0) {
	anumber -= afs_freeDCCount;
	if (anumber <= 0)
	    return;		/* enough already free */
    }
    /* bounds check parameter */
    if (anumber > MAXATONCE)
	anumber = MAXATONCE;	/* all we can do */

    /*
     * The phase variable manages reclaims.  Set to 0, the first pass,
     * we don't reclaim active entries.  Set to 1, we reclaim even active
     * ones.
     */
    phase = 0;
    for (i = 0; i < afs_cacheFiles; i++)
	/* turn off all flags */
	afs_indexFlags[i] &= ~IFFlag;

    while (anumber > 0 || (aneedSpace && *aneedSpace > 0)) {
	/* find oldest entries for reclamation */
	maxVictimPtr = victimPtr = 0;
	hzero(maxVictimTime);
	/* select victims from access time array */
	for (i = 0; i < afs_cacheFiles; i++) {
	    if (afs_indexFlags[i] & (IFDataMod | IFFree | IFDiscarded)) {
		/* skip if dirty or already free */
		continue;
	    }
	    tdc = afs_indexTable[i];
	    if (tdc && (tdc->refCount != 0)) {
		/* Referenced; can't use it! */
		continue;
	    }
	    hset(vtime, afs_indexTimes[i]);

	    /* if we've already looked at this one, skip it */
	    if (afs_indexFlags[i] & IFFlag)
		continue;

	    if (victimPtr < MAXATONCE) {
		/* if there's at least one free victim slot left */
		victims[victimPtr] = i;
		hset(victimTimes[victimPtr], vtime);
		if (hcmp(vtime, maxVictimTime) > 0) {
		    hset(maxVictimTime, vtime);
		    maxVictimPtr = victimPtr;
		}
		victimPtr++;
	    } else if (hcmp(vtime, maxVictimTime) < 0) {
		/*
		 * We're older than youngest victim, so we replace at
		 * least one victim
		 */
		/* find youngest (largest LRU) victim */
		j = maxVictimPtr;
		if (j == victimPtr)
		    osi_Panic("getdownd local");
		victims[j] = i;
		hset(victimTimes[j], vtime);
		/* recompute maxVictimTime */
		hset(maxVictimTime, vtime);
		for (j = 0; j < victimPtr; j++)
		    if (hcmp(maxVictimTime, victimTimes[j]) < 0) {
			hset(maxVictimTime, victimTimes[j]);
			maxVictimPtr = j;
		    }
	    }
	}			/* big for loop */

	/* now really reclaim the victims */
	j = 0;			/* flag to track if we actually got any of the victims */
	/* first, hold all the victims, since we're going to release the lock
	 * during the truncate operation.
	 */
	for (i = 0; i < victimPtr; i++) {
	    tdc = afs_GetDSlot(victims[i], 0);
	    /* We got tdc->tlock(R) here */
	    if (tdc->refCount == 1)
		victimDCs[i] = tdc;
	    else
		victimDCs[i] = 0;
	    ReleaseReadLock(&tdc->tlock);
	    if (!victimDCs[i])
		afs_PutDCache(tdc);
	}
	for (i = 0; i < victimPtr; i++) {
	    /* q is first elt in dcache entry */
	    tdc = victimDCs[i];
	    /* now, since we're dropping the afs_xdcache lock below, we
	     * have to verify, before proceeding, that there are no other
	     * references to this dcache entry, even now.  Note that we
	     * compare with 1, since we bumped it above when we called
	     * afs_GetDSlot to preserve the entry's identity.
	     */
	    if (tdc && tdc->refCount == 1) {
		unsigned char chunkFlags;
		afs_size_t tchunkoffset = 0;
		afid = &tdc->f.fid;
		/* xdcache is lower than the xvcache lock */
		MReleaseWriteLock(&afs_xdcache);
		MObtainReadLock(&afs_xvcache);
		tvc = afs_FindVCache(afid, 0, 0 /* no stats, no vlru */ );
		MReleaseReadLock(&afs_xvcache);
		MObtainWriteLock(&afs_xdcache, 527);
		skip = 0;
		if (tdc->refCount > 1)
		    skip = 1;
		if (tvc) {
		    tchunkoffset = AFS_CHUNKTOBASE(tdc->f.chunk);
		    chunkFlags = afs_indexFlags[tdc->index];
		    if (phase == 0 && osi_Active(tvc))
			skip = 1;
		    if (phase > 0 && osi_Active(tvc)
			&& (tvc->states & CDCLock)
			&& (chunkFlags & IFAnyPages))
			skip = 1;
		    if (chunkFlags & IFDataMod)
			skip = 1;
		    afs_Trace4(afs_iclSetp, CM_TRACE_GETDOWND,
			       ICL_TYPE_POINTER, tvc, ICL_TYPE_INT32, skip,
			       ICL_TYPE_INT32, tdc->index, ICL_TYPE_OFFSET,
			       ICL_HANDLE_OFFSET(tchunkoffset));

#if	defined(AFS_SUN5_ENV)
		    /*
		     * Now we try to invalidate pages.  We do this only for
		     * Solaris.  For other platforms, it's OK to recycle a
		     * dcache entry out from under a page, because the strategy
		     * function can call afs_GetDCache().
		     */
		    if (!skip && (chunkFlags & IFAnyPages)) {
			int code;

			MReleaseWriteLock(&afs_xdcache);
			MObtainWriteLock(&tvc->vlock, 543);
			if (tvc->multiPage) {
			    skip = 1;
			    goto endmultipage;
			}
			/* block locking pages */
			tvc->vstates |= VPageCleaning;
			/* block getting new pages */
			tvc->activeV++;
			MReleaseWriteLock(&tvc->vlock);
			/* One last recheck */
			MObtainWriteLock(&afs_xdcache, 333);
			chunkFlags = afs_indexFlags[tdc->index];
			if (tdc->refCount > 1 || (chunkFlags & IFDataMod)
			    || (osi_Active(tvc) && (tvc->states & CDCLock)
				&& (chunkFlags & IFAnyPages))) {
			    skip = 1;
			    MReleaseWriteLock(&afs_xdcache);
			    goto endputpage;
			}
			MReleaseWriteLock(&afs_xdcache);

			code = osi_VM_GetDownD(tvc, tdc);

			MObtainWriteLock(&afs_xdcache, 269);
			/* we actually removed all pages, clean and dirty */
			if (code == 0) {
			    afs_indexFlags[tdc->index] &=
				~(IFDirtyPages | IFAnyPages);
			} else
			    skip = 1;
			MReleaseWriteLock(&afs_xdcache);
		      endputpage:
			MObtainWriteLock(&tvc->vlock, 544);
			if (--tvc->activeV == 0
			    && (tvc->vstates & VRevokeWait)) {
			    tvc->vstates &= ~VRevokeWait;
			    afs_osi_Wakeup((char *)&tvc->vstates);

			}
			if (tvc->vstates & VPageCleaning) {
			    tvc->vstates &= ~VPageCleaning;
			    afs_osi_Wakeup((char *)&tvc->vstates);
			}
		      endmultipage:
			MReleaseWriteLock(&tvc->vlock);
		    } else
#endif /* AFS_SUN5_ENV */
		    {
			MReleaseWriteLock(&afs_xdcache);
		    }

		    AFS_FAST_RELE(tvc);
		    MObtainWriteLock(&afs_xdcache, 528);
		    if (afs_indexFlags[tdc->index] &
			(IFDataMod | IFDirtyPages | IFAnyPages))
			skip = 1;
		    if (tdc->refCount > 1)
			skip = 1;
		}
#if	defined(AFS_SUN5_ENV)
		else {
		    /* no vnode, so IFDirtyPages is spurious (we don't
		     * sweep dcaches on vnode recycling, so we can have
		     * DIRTYPAGES set even when all pages are gone).  Just
		     * clear the flag.
		     * Hold vcache lock to prevent vnode from being
		     * created while we're clearing IFDirtyPages.
		     */
		    afs_indexFlags[tdc->index] &=
			~(IFDirtyPages | IFAnyPages);
		}
#endif
		if (skip) {
		    /* skip this guy and mark him as recently used */
		    afs_indexFlags[tdc->index] |= IFFlag;
		    afs_Trace4(afs_iclSetp, CM_TRACE_GETDOWND,
			       ICL_TYPE_POINTER, tvc, ICL_TYPE_INT32, 2,
			       ICL_TYPE_INT32, tdc->index, ICL_TYPE_OFFSET,
			       ICL_HANDLE_OFFSET(tchunkoffset));
		} else {
		    /* flush this dude from the data cache and reclaim;
		     * first, make sure no one will care that we damage
		     * it, by removing it from all hash tables.  Then,
		     * melt it down for parts.  Note that any concurrent
		     * (new possibility!) calls to GetDownD won't touch
		     * this guy because his reference count is > 0. */
		    afs_Trace4(afs_iclSetp, CM_TRACE_GETDOWND,
			       ICL_TYPE_POINTER, tvc, ICL_TYPE_INT32, 3,
			       ICL_TYPE_INT32, tdc->index, ICL_TYPE_OFFSET,
			       ICL_HANDLE_OFFSET(tchunkoffset));
#ifndef	AFS_DEC_ENV
		    AFS_STATCNT(afs_gget);
#endif
		    afs_HashOutDCache(tdc);
		    if (tdc->f.chunkBytes != 0) {
			discard = 1;
			if (aneedSpace)
			    *aneedSpace -=
				(tdc->f.chunkBytes + afs_fsfragsize) >> 10;
		    } else {
			discard = 0;
		    }
		    if (discard) {
			afs_DiscardDCache(tdc);
		    } else {
			afs_FreeDCache(tdc);
		    }
		    anumber--;
		    j = 1;	/* we reclaimed at least one victim */
		}
	    }
	    afs_PutDCache(tdc);
	}

	if (phase == 0) {
	    /* Phase is 0 and no one was found, so try phase 1 (ignore
	     * osi_Active flag) */
	    if (j == 0) {
		phase = 1;
		for (i = 0; i < afs_cacheFiles; i++)
		    /* turn off all flags */
		    afs_indexFlags[i] &= ~IFFlag;
	    }
	} else {
	    /* found no one in phase 1, we're hosed */
	    if (victimPtr == 0)
		break;
	}
    }				/* big while loop */
    return;

}				/*afs_GetDownD */


/*
 * Description: remove adc from any hash tables that would allow it to be located
 * again by afs_FindDCache or afs_GetDCache.
 *
 * Parameters: adc -- pointer to dcache entry to remove from hash tables.
 *
 * Locks: Must have the afs_xdcache lock write-locked to call this function.
 */
int
afs_HashOutDCache(struct dcache *adc)
{
    int i, us;

#ifndef	AFS_DEC_ENV
    AFS_STATCNT(afs_glink);
#endif
    /* we know this guy's in the LRUQ.  We'll move dude into DCQ below */
    DZap(&adc->f.inode);
    /* if this guy is in the hash table, pull him out */
    if (adc->f.fid.Fid.Volume != 0) {
	/* remove entry from first hash chains */
	i = DCHash(&adc->f.fid, adc->f.chunk);
	us = afs_dchashTbl[i];
	if (us == adc->index) {
	    /* first dude in the list */
	    afs_dchashTbl[i] = afs_dcnextTbl[adc->index];
	} else {
	    /* somewhere on the chain */
	    while (us != NULLIDX) {
		if (afs_dcnextTbl[us] == adc->index) {
		    /* found item pointing at the one to delete */
		    afs_dcnextTbl[us] = afs_dcnextTbl[adc->index];
		    break;
		}
		us = afs_dcnextTbl[us];
	    }
	    if (us == NULLIDX)
		osi_Panic("dcache hc");
	}
	/* remove entry from *other* hash chain */
	i = DVHash(&adc->f.fid);
	us = afs_dvhashTbl[i];
	if (us == adc->index) {
	    /* first dude in the list */
	    afs_dvhashTbl[i] = afs_dvnextTbl[adc->index];
	} else {
	    /* somewhere on the chain */
	    while (us != NULLIDX) {
		if (afs_dvnextTbl[us] == adc->index) {
		    /* found item pointing at the one to delete */
		    afs_dvnextTbl[us] = afs_dvnextTbl[adc->index];
		    break;
		}
		us = afs_dvnextTbl[us];
	    }
	    if (us == NULLIDX)
		osi_Panic("dcache hv");
	}
    }

    /* prevent entry from being found on a reboot (it is already out of
     * the hash table, but after a crash, we just look at fid fields of
     * stable (old) entries).
     */
    adc->f.fid.Fid.Volume = 0;	/* invalid */

    /* mark entry as modified */
    adc->dflags |= DFEntryMod;

    /* all done */
    return 0;
}				/*afs_HashOutDCache */


/*
 * afs_FlushDCache
 *
 * Description:
 *	Flush the given dcache entry, pulling it from hash chains
 *	and truncating the associated cache file.
 *
 * Arguments:
 *	adc: Ptr to dcache entry to flush.
 *
 * Environment:
 *	This routine must be called with the afs_xdcache lock held
 *	(in write mode)
 */

void
afs_FlushDCache(register struct dcache *adc)
{
    AFS_STATCNT(afs_FlushDCache);
    /*
     * Bump the number of cache files flushed.
     */
    afs_stats_cmperf.cacheFlushes++;

    /* remove from all hash tables */
    afs_HashOutDCache(adc);

    /* Free its space; special case null operation, since truncate operation
     * in UFS is slow even in this case, and this allows us to pre-truncate
     * these files at more convenient times with fewer locks set
     * (see afs_GetDownD).
     */
    if (adc->f.chunkBytes != 0) {
	afs_DiscardDCache(adc);
	afs_MaybeWakeupTruncateDaemon();
    } else {
	afs_FreeDCache(adc);
    }

    if (afs_WaitForCacheDrain) {
	if (afs_blocksUsed <=
	    (CM_CACHESIZEDRAINEDPCT * afs_cacheBlocks) / 100) {
	    afs_WaitForCacheDrain = 0;
	    afs_osi_Wakeup(&afs_WaitForCacheDrain);
	}
    }
}				/*afs_FlushDCache */


/*
 * afs_FreeDCache
 *
 * Description: put a dcache entry on the free dcache entry list.
 *
 * Parameters: adc -- dcache entry to free
 *
 * Environment: called with afs_xdcache lock write-locked.
 */
static void
afs_FreeDCache(register struct dcache *adc)
{
    /* Thread on free list, update free list count and mark entry as
     * freed in its indexFlags element.  Also, ensure DCache entry gets
     * written out (set DFEntryMod).
     */

    afs_dvnextTbl[adc->index] = afs_freeDCList;
    afs_freeDCList = adc->index;
    afs_freeDCCount++;
    afs_indexFlags[adc->index] |= IFFree;
    adc->dflags |= DFEntryMod;

    if (afs_WaitForCacheDrain) {
	if ((afs_blocksUsed - afs_blocksDiscarded) <=
	    (CM_CACHESIZEDRAINEDPCT * afs_cacheBlocks) / 100) {
	    afs_WaitForCacheDrain = 0;
	    afs_osi_Wakeup(&afs_WaitForCacheDrain);
	}
    }
}

/*
 * afs_DiscardDCache
 *
 * Description:
 * 	Discard the cache element by moving it to the discardDCList.
 *      This puts the cache element into a quasi-freed state, where
 *      the space may be reused, but the file has not been truncated.
 *
 * Major Assumptions Here:
 *      Assumes that frag size is an integral power of two, less one,
 *      and that this is a two's complement machine.  I don't
 *      know of any filesystems which violate this assumption...
 *
 * Parameters:
 *	adc	 : Ptr to dcache entry.
 *
 * Environment:
 *	Must be called with afs_xdcache write-locked.
 */

static void
afs_DiscardDCache(register struct dcache *adc)
{
    register afs_int32 size;

    AFS_STATCNT(afs_DiscardDCache);

    osi_Assert(adc->refCount == 1);

    size = ((adc->f.chunkBytes + afs_fsfragsize) ^ afs_fsfragsize) >> 10;	/* round up */
    afs_blocksDiscarded += size;
    afs_stats_cmperf.cacheBlocksDiscarded = afs_blocksDiscarded;

    afs_dvnextTbl[adc->index] = afs_discardDCList;
    afs_discardDCList = adc->index;
    afs_discardDCCount++;

    adc->f.fid.Fid.Volume = 0;
    adc->dflags |= DFEntryMod;
    afs_indexFlags[adc->index] |= IFDiscarded;

    if (afs_WaitForCacheDrain) {
	if ((afs_blocksUsed - afs_blocksDiscarded) <=
	    (CM_CACHESIZEDRAINEDPCT * afs_cacheBlocks) / 100) {
	    afs_WaitForCacheDrain = 0;
	    afs_osi_Wakeup(&afs_WaitForCacheDrain);
	}
    }

}				/*afs_DiscardDCache */

/*
 * afs_FreeDiscardedDCache
 *
 * Description:
 *     Free the next element on the list of discarded cache elements.
 */
static void
afs_FreeDiscardedDCache(void)
{
    register struct dcache *tdc;
    register struct osi_file *tfile;
    register afs_int32 size;

    AFS_STATCNT(afs_FreeDiscardedDCache);

    MObtainWriteLock(&afs_xdcache, 510);
    if (!afs_blocksDiscarded) {
	MReleaseWriteLock(&afs_xdcache);
	return;
    }

    /*
     * Get an entry from the list of discarded cache elements
     */
    tdc = afs_GetDSlot(afs_discardDCList, 0);
    osi_Assert(tdc->refCount == 1);
    ReleaseReadLock(&tdc->tlock);

    afs_discardDCList = afs_dvnextTbl[tdc->index];
    afs_dvnextTbl[tdc->index] = NULLIDX;
    afs_discardDCCount--;
    size = ((tdc->f.chunkBytes + afs_fsfragsize) ^ afs_fsfragsize) >> 10;	/* round up */
    afs_blocksDiscarded -= size;
    afs_stats_cmperf.cacheBlocksDiscarded = afs_blocksDiscarded;
    /* We can lock because we just took it off the free list */
    ObtainWriteLock(&tdc->lock, 626);
    MReleaseWriteLock(&afs_xdcache);

    /*
     * Truncate the element to reclaim its space
     */
    tfile = afs_CFileOpen(tdc->f.inode);
    afs_CFileTruncate(tfile, 0);
    afs_CFileClose(tfile);
    afs_AdjustSize(tdc, 0);

    /*
     * Free the element we just truncated
     */
    MObtainWriteLock(&afs_xdcache, 511);
    afs_indexFlags[tdc->index] &= ~IFDiscarded;
    afs_FreeDCache(tdc);
    ReleaseWriteLock(&tdc->lock);
    afs_PutDCache(tdc);
    MReleaseWriteLock(&afs_xdcache);
}

/*
 * afs_MaybeFreeDiscardedDCache
 *
 * Description:
 *      Free as many entries from the list of discarded cache elements
 *      as we need to get the free space down below CM_WAITFORDRAINPCT (98%).
 *
 * Parameters:
 *      None
 */
int
afs_MaybeFreeDiscardedDCache(void)
{

    AFS_STATCNT(afs_MaybeFreeDiscardedDCache);

    while (afs_blocksDiscarded
	   && (afs_blocksUsed >
	       (CM_WAITFORDRAINPCT * afs_cacheBlocks) / 100)) {
	afs_FreeDiscardedDCache();
    }
    return 0;
}

/*
 * afs_GetDownDSlot
 *
 * Description:
 *	Try to free up a certain number of disk slots.
 *
 * Parameters:
 *	anumber : Targeted number of disk slots to free up.
 *
 * Environment:
 *	Must be called with afs_xdcache write-locked.
 */
static void
afs_GetDownDSlot(int anumber)
{
    struct afs_q *tq, *nq;
    struct dcache *tdc;
    int ix;
    unsigned int cnt;

    AFS_STATCNT(afs_GetDownDSlot);
    if (cacheDiskType == AFS_FCACHE_TYPE_MEM)
	osi_Panic("diskless getdowndslot");

    if (CheckLock(&afs_xdcache) != -1)
	osi_Panic("getdowndslot nolock");

    /* decrement anumber first for all dudes in free list */
    for (tdc = afs_freeDSList; tdc; tdc = (struct dcache *)tdc->lruq.next)
	anumber--;
    if (anumber <= 0)
	return;			/* enough already free */

    for (cnt = 0, tq = afs_DLRU.prev; tq != &afs_DLRU && anumber > 0;
	 tq = nq, cnt++) {
	tdc = (struct dcache *)tq;	/* q is first elt in dcache entry */
	nq = QPrev(tq);		/* in case we remove it */
	if (tdc->refCount == 0) {
	    if ((ix = tdc->index) == NULLIDX)
		osi_Panic("getdowndslot");
	    /* pull the entry out of the lruq and put it on the free list */
	    QRemove(&tdc->lruq);

	    /* write-through if modified */
	    if (tdc->dflags & DFEntryMod) {
#if defined(AFS_SGI_ENV) && defined(AFS_SGI_SHORTSTACK)
		/*
		 * ask proxy to do this for us - we don't have the stack space
		 */
		while (tdc->dflags & DFEntryMod) {
		    int s;
		    AFS_GUNLOCK();
		    s = SPLOCK(afs_sgibklock);
		    if (afs_sgibklist == NULL) {
			/* if slot is free, grab it. */
			afs_sgibklist = tdc;
			SV_SIGNAL(&afs_sgibksync);
		    }
		    /* wait for daemon to (start, then) finish. */
		    SP_WAIT(afs_sgibklock, s, &afs_sgibkwait, PINOD);
		    AFS_GLOCK();
		}
#else
		tdc->dflags &= ~DFEntryMod;
		afs_WriteDCache(tdc, 1);
#endif
	    }

	    tdc->stamp = 0;
#ifdef IHINT
	    if (tdc->ihint) {
		struct osi_file *f = (struct osi_file *)tdc->ihint;
		tdc->ihint = 0;
		afs_UFSClose(f);
		nihints--;
	    }
#endif /* IHINT */


	    /* finally put the entry in the free list */
	    afs_indexTable[ix] = NULL;
	    afs_indexFlags[ix] &= ~IFEverUsed;
	    tdc->index = NULLIDX;
	    tdc->lruq.next = (struct afs_q *)afs_freeDSList;
	    afs_freeDSList = tdc;
	    anumber--;
	}
    }
}				/*afs_GetDownDSlot */


/*
 * afs_RefDCache
 *
 * Description:
 *	Increment the reference count on a disk cache entry,
 *	which already has a non-zero refcount.  In order to
 *	increment the refcount of a zero-reference entry, you
 *	have to hold afs_xdcache.
 *
 * Parameters:
 *	adc : Pointer to the dcache entry to increment.
 *
 * Environment:
 *	Nothing interesting.
 */
int
afs_RefDCache(struct dcache *adc)
{
    ObtainWriteLock(&adc->tlock, 627);
    if (adc->refCount < 0)
	osi_Panic("RefDCache: negative refcount");
    adc->refCount++;
    ReleaseWriteLock(&adc->tlock);
    return 0;
}


/*
 * afs_PutDCache
 *
 * Description:
 *	Decrement the reference count on a disk cache entry.
 *
 * Parameters:
 *	ad : Ptr to the dcache entry to decrement.
 *
 * Environment:
 *	Nothing interesting.
 */
int
afs_PutDCache(register struct dcache *adc)
{
    AFS_STATCNT(afs_PutDCache);
    ObtainWriteLock(&adc->tlock, 276);
    if (adc->refCount <= 0)
	osi_Panic("putdcache");
    --adc->refCount;
    ReleaseWriteLock(&adc->tlock);
    return 0;
}


/*
 * afs_TryToSmush
 *
 * Description:
 *	Try to discard all data associated with this file from the
 *	cache.
 *
 * Parameters:
 *	avc : Pointer to the cache info for the file.
 *
 * Environment:
 *	Both pvnLock and lock are write held.
 */
void
afs_TryToSmush(register struct vcache *avc, struct AFS_UCRED *acred, int sync)
{
    register struct dcache *tdc;
    register int index;
    register int i;
    AFS_STATCNT(afs_TryToSmush);
    afs_Trace2(afs_iclSetp, CM_TRACE_TRYTOSMUSH, ICL_TYPE_POINTER, avc,
	       ICL_TYPE_OFFSET, ICL_HANDLE_OFFSET(avc->m.Length));
    sync = 1;			/* XX Temp testing XX */

#if     defined(AFS_SUN5_ENV)
    ObtainWriteLock(&avc->vlock, 573);
    avc->activeV++;		/* block new getpages */
    ReleaseWriteLock(&avc->vlock);
#endif

    /* Flush VM pages */
    osi_VM_TryToSmush(avc, acred, sync);

    /*
     * Get the hash chain containing all dce's for this fid
     */
    i = DVHash(&avc->fid);
    MObtainWriteLock(&afs_xdcache, 277);
    for (index = afs_dvhashTbl[i]; index != NULLIDX; index = i) {
	i = afs_dvnextTbl[index];	/* next pointer this hash table */
	if (afs_indexUnique[index] == avc->fid.Fid.Unique) {
	    int releaseTlock = 1;
	    tdc = afs_GetDSlot(index, NULL);
	    if (!FidCmp(&tdc->f.fid, &avc->fid)) {
		if (sync) {
		    if ((afs_indexFlags[index] & IFDataMod) == 0
			&& tdc->refCount == 1) {
			ReleaseReadLock(&tdc->tlock);
			releaseTlock = 0;
			afs_FlushDCache(tdc);
		    }
		} else
		    afs_indexTable[index] = 0;
	    }
	    if (releaseTlock)
		ReleaseReadLock(&tdc->tlock);
	    afs_PutDCache(tdc);
	}
    }
#if	defined(AFS_SUN5_ENV)
    ObtainWriteLock(&avc->vlock, 545);
    if (--avc->activeV == 0 && (avc->vstates & VRevokeWait)) {
	avc->vstates &= ~VRevokeWait;
	afs_osi_Wakeup((char *)&avc->vstates);
    }
    ReleaseWriteLock(&avc->vlock);
#endif
    MReleaseWriteLock(&afs_xdcache);
    /*
     * It's treated like a callback so that when we do lookups we'll invalidate the unique bit if any
     * trytoSmush occured during the lookup call
     */
    afs_allCBs++;
}

/*
 * afs_FindDCache
 *
 * Description:
 *	Given the cached info for a file and a byte offset into the
 *	file, make sure the dcache entry for that file and containing
 *	the given byte is available, returning it to our caller.
 *
 * Parameters:
 *	avc   : Pointer to the (held) vcache entry to look in.
 *	abyte : Which byte we want to get to.
 *
 * Returns:
 *	Pointer to the dcache entry covering the file & desired byte,
 *	or NULL if not found.
 *
 * Environment:
 *	The vcache entry is held upon entry.
 */

struct dcache *
afs_FindDCache(register struct vcache *avc, afs_size_t abyte)
{
    afs_int32 chunk;
    register afs_int32 i, index;
    register struct dcache *tdc;

    AFS_STATCNT(afs_FindDCache);
    chunk = AFS_CHUNK(abyte);

    /*
     * Hash on the [fid, chunk] and get the corresponding dcache index
     * after write-locking the dcache.
     */
    i = DCHash(&avc->fid, chunk);
    MObtainWriteLock(&afs_xdcache, 278);
    for (index = afs_dchashTbl[i]; index != NULLIDX;) {
	if (afs_indexUnique[index] == avc->fid.Fid.Unique) {
	    tdc = afs_GetDSlot(index, NULL);
	    ReleaseReadLock(&tdc->tlock);
	    if (!FidCmp(&tdc->f.fid, &avc->fid) && chunk == tdc->f.chunk) {
		break;		/* leaving refCount high for caller */
	    }
	    afs_PutDCache(tdc);
	}
	index = afs_dcnextTbl[index];
    }
    MReleaseWriteLock(&afs_xdcache);
    if (index != NULLIDX) {
	hset(afs_indexTimes[tdc->index], afs_indexCounter);
	hadd32(afs_indexCounter, 1);
	return tdc;
    } else
	return NULL;

}				/*afs_FindDCache */


/*
 * afs_UFSCacheStoreProc
 *
 * Description:
 *	Called upon store.
 *
 * Parameters:
 *	acall : Ptr to the Rx call structure involved.
 *	afile : Ptr to the related file descriptor.
 *	alen  : Size of the file in bytes.
 *	avc   : Ptr to the vcache entry.
 *      shouldWake : is it "safe" to return early from close() ?
 *	abytesToXferP  : Set to the number of bytes to xfer.
 *			 NOTE: This parameter is only used if AFS_NOSTATS
 *				is not defined.
 *	abytesXferredP : Set to the number of bytes actually xferred.
 *			 NOTE: This parameter is only used if AFS_NOSTATS
 *				is not defined.
 *
 * Environment:
 *	Nothing interesting.
 */
static int
afs_UFSCacheStoreProc(register struct rx_call *acall, struct osi_file *afile,
		      register afs_int32 alen, struct vcache *avc,
		      int *shouldWake, afs_size_t * abytesToXferP,
		      afs_size_t * abytesXferredP)
{
    afs_int32 code, got;
    register char *tbuffer;
    register int tlen;

    AFS_STATCNT(UFS_CacheStoreProc);

#ifndef AFS_NOSTATS
    /*
     * In this case, alen is *always* the amount of data we'll be trying
     * to ship here.
     */
    (*abytesToXferP) = alen;
    (*abytesXferredP) = 0;
#endif /* AFS_NOSTATS */

    afs_Trace4(afs_iclSetp, CM_TRACE_STOREPROC, ICL_TYPE_POINTER, avc,
	       ICL_TYPE_FID, &(avc->fid), ICL_TYPE_OFFSET,
	       ICL_HANDLE_OFFSET(avc->m.Length), ICL_TYPE_INT32, alen);
    tbuffer = osi_AllocLargeSpace(AFS_LRALLOCSIZ);
    while (alen > 0) {
	tlen = (alen > AFS_LRALLOCSIZ ? AFS_LRALLOCSIZ : alen);
	got = afs_osi_Read(afile, -1, tbuffer, tlen);
	if ((got < 0)
#if defined(KERNEL_HAVE_UERROR)
	    || (got != tlen && getuerror())
#endif
	    ) {
	    osi_FreeLargeSpace(tbuffer);
	    return EIO;
	}
	afs_Trace2(afs_iclSetp, CM_TRACE_STOREPROC2, ICL_TYPE_OFFSET,
		   ICL_HANDLE_OFFSET(*tbuffer), ICL_TYPE_INT32, got);
	RX_AFS_GUNLOCK();
	code = rx_Write(acall, tbuffer, got);	/* writing 0 bytes will
						 * push a short packet.  Is that really what we want, just because the
						 * data didn't come back from the disk yet?  Let's try it and see. */
	RX_AFS_GLOCK();
#ifndef AFS_NOSTATS
	(*abytesXferredP) += code;
#endif /* AFS_NOSTATS */
	if (code != got) {
	    osi_FreeLargeSpace(tbuffer);
	    return -33;
	}
	alen -= got;
	/*
	 * If file has been locked on server, we can allow the store
	 * to continue.
	 */
	if (shouldWake && *shouldWake && (rx_GetRemoteStatus(acall) & 1)) {
	    *shouldWake = 0;	/* only do this once */
	    afs_wakeup(avc);
	}
    }
    afs_Trace4(afs_iclSetp, CM_TRACE_STOREPROC, ICL_TYPE_POINTER, avc,
	       ICL_TYPE_FID, &(avc->fid), ICL_TYPE_OFFSET,
	       ICL_HANDLE_OFFSET(avc->m.Length), ICL_TYPE_INT32, alen);
    osi_FreeLargeSpace(tbuffer);
    return 0;

}				/* afs_UFSCacheStoreProc */


/*
 * afs_UFSCacheFetchProc
 *
 * Description:
 *	Routine called on fetch; also tells people waiting for data
 *	that more has arrived.
 *
 * Parameters:
 *	acall : Ptr to the Rx call structure.
 *	afile : File descriptor for the cache file.
 *	abase : Base offset to fetch.
 *	adc   : Ptr to the dcache entry for the file, write-locked.
 *      avc   : Ptr to the vcache entry for the file.
 *	abytesToXferP  : Set to the number of bytes to xfer.
 *			 NOTE: This parameter is only used if AFS_NOSTATS
 *				is not defined.
 *	abytesXferredP : Set to the number of bytes actually xferred.
 *			 NOTE: This parameter is only used if AFS_NOSTATS
 *				is not defined.
 *
 * Environment:
 *	Nothing interesting.
 */

static int
afs_UFSCacheFetchProc(register struct rx_call *acall, struct osi_file *afile,
		      afs_size_t abase, struct dcache *adc,
		      struct vcache *avc, afs_size_t * abytesToXferP,
		      afs_size_t * abytesXferredP, afs_int32 lengthFound)
{
    afs_int32 length;
    register afs_int32 code;
    register char *tbuffer;
    register int tlen;
    int moredata = 0;

    AFS_STATCNT(UFS_CacheFetchProc);
    osi_Assert(WriteLocked(&adc->lock));
    afile->offset = 0;		/* Each time start from the beginning */
    length = lengthFound;
#ifndef AFS_NOSTATS
    (*abytesToXferP) = 0;
    (*abytesXferredP) = 0;
#endif /* AFS_NOSTATS */
    tbuffer = osi_AllocLargeSpace(AFS_LRALLOCSIZ);
    adc->validPos = abase;
    do {
	if (moredata) {
	    RX_AFS_GUNLOCK();
	    code = rx_Read(acall, (char *)&length, sizeof(afs_int32));
	    RX_AFS_GLOCK();
	    length = ntohl(length);
	    if (code != sizeof(afs_int32)) {
		osi_FreeLargeSpace(tbuffer);
		code = rx_Error(acall);
		return (code ? code : -1);	/* try to return code, not -1 */
	    }
	}
	/*
	 * The fetch protocol is extended for the AFS/DFS translator
	 * to allow multiple blocks of data, each with its own length,
	 * to be returned. As long as the top bit is set, there are more
	 * blocks expected.
	 *
	 * We do not do this for AFS file servers because they sometimes
	 * return large negative numbers as the transfer size.
	 */
	if (avc->states & CForeign) {
	    moredata = length & 0x80000000;
	    length &= ~0x80000000;
	} else {
	    moredata = 0;
	}
#ifndef AFS_NOSTATS
	(*abytesToXferP) += length;
#endif /* AFS_NOSTATS */
	while (length > 0) {
	    tlen = (length > AFS_LRALLOCSIZ ? AFS_LRALLOCSIZ : length);
#ifdef RX_KERNEL_TRACE
	    afs_Trace1(afs_iclSetp, CM_TRACE_TIMESTAMP, ICL_TYPE_STRING,
		       "before rx_Read");
#endif
	    RX_AFS_GUNLOCK();
	    code = rx_Read(acall, tbuffer, tlen);
	    RX_AFS_GLOCK();
#ifdef RX_KERNEL_TRACE
	    afs_Trace1(afs_iclSetp, CM_TRACE_TIMESTAMP, ICL_TYPE_STRING,
		       "after rx_Read");
#endif
#ifndef AFS_NOSTATS
	    (*abytesXferredP) += code;
#endif /* AFS_NOSTATS */
	    if (code != tlen) {
		osi_FreeLargeSpace(tbuffer);
		afs_Trace3(afs_iclSetp, CM_TRACE_FETCH64READ,
			   ICL_TYPE_POINTER, avc, ICL_TYPE_INT32, code,
			   ICL_TYPE_INT32, length);
		return -34;
	    }
	    code = afs_osi_Write(afile, -1, tbuffer, tlen);
	    if (code != tlen) {
		osi_FreeLargeSpace(tbuffer);
		return EIO;
	    }
	    abase += tlen;
	    length -= tlen;
	    adc->validPos = abase;
	    if (afs_osi_Wakeup(&adc->validPos) == 0)
		afs_Trace4(afs_iclSetp, CM_TRACE_DCACHEWAKE, ICL_TYPE_STRING,
			   __FILE__, ICL_TYPE_INT32, __LINE__,
			   ICL_TYPE_POINTER, adc, ICL_TYPE_INT32,
			   adc->dflags);
	}
    } while (moredata);
    osi_FreeLargeSpace(tbuffer);
    return 0;

}				/* afs_UFSCacheFetchProc */

/*
 * afs_GetDCache
 *
 * Description:
 *	This function is called to obtain a reference to data stored in
 *	the disk cache, locating a chunk of data containing the desired
 *	byte and returning a reference to the disk cache entry, with its
 *	reference count incremented.
 *
 * Parameters:
 * IN:
 *	avc     : Ptr to a vcache entry (unlocked)
 *	abyte   : Byte position in the file desired
 *	areq    : Request structure identifying the requesting user.
 *	aflags  : Settings as follows:
 *			1 : Set locks
 *			2 : Return after creating entry.
 *			4 : called from afs_vnop_write.c
 *			    *alen contains length of data to be written.
 * OUT:
 *	aoffset : Set to the offset within the chunk where the resident
 *		  byte is located.
 *	alen    : Set to the number of bytes of data after the desired
 *		  byte (including the byte itself) which can be read
 *		  from this chunk.
 *
 * Environment:
 *	The vcache entry pointed to by avc is unlocked upon entry.
 */

struct tlocal1 {
    struct AFSVolSync tsync;
    struct AFSFetchStatus OutStatus;
    struct AFSCallBack CallBack;
};

/*
 * Update the vnode-to-dcache hint if we can get the vnode lock
 * right away.  Assumes dcache entry is at least read-locked.
 */
void
updateV2DC(int lockVc, struct vcache *v, struct dcache *d, int src)
{
    if (!lockVc || 0 == NBObtainWriteLock(&v->lock, src)) {
	if (hsame(v->m.DataVersion, d->f.versionNo) && v->callback) {
	    v->quick.dc = d;
	    v->quick.stamp = d->stamp = MakeStamp();
	    v->quick.minLoc = AFS_CHUNKTOBASE(d->f.chunk);
	    /* Don't think I need these next two lines forever */
	    v->quick.len = d->f.chunkBytes;
	    v->h1.dchint = d;
	}
	if (lockVc)
	    ReleaseWriteLock(&v->lock);
    }
}

/* avc - Write-locked unless aflags & 1 */
struct dcache *
afs_GetDCache(register struct vcache *avc, afs_size_t abyte,
	      register struct vrequest *areq, afs_size_t * aoffset,
	      afs_size_t * alen, int aflags)
{
    register afs_int32 i, code, code1 = 0, shortcut;
#if	defined(AFS_AIX32_ENV) || defined(AFS_SGI_ENV)
    register afs_int32 adjustsize = 0;
#endif
    int setLocks;
    afs_int32 index;
    afs_int32 us;
    afs_int32 chunk;
    afs_size_t maxGoodLength;	/* amount of good data at server */
    struct rx_call *tcall;
    afs_size_t Position = 0;
#ifdef AFS_64BIT_CLIENT
    afs_size_t tsize;
    afs_size_t lengthFound;	/* as returned from server */
#endif /* AFS_64BIT_CLIENT */
    afs_int32 size, tlen;	/* size of segment to transfer */
    struct tlocal1 *tsmall = 0;
    register struct dcache *tdc;
    register struct osi_file *file;
    register struct conn *tc;
    int downDCount = 0;
    struct server *newCallback;
    char setNewCallback;
    char setVcacheStatus;
    char doVcacheUpdate;
    char slowPass = 0;
    int doAdjustSize = 0;
    int doReallyAdjustSize = 0;
    int overWriteWholeChunk = 0;

    XSTATS_DECLS
#ifndef AFS_NOSTATS
    struct afs_stats_xferData *xferP;	/* Ptr to this op's xfer struct */
    osi_timeval_t xferStartTime,	/*FS xfer start time */
      xferStopTime;		/*FS xfer stop time */
    afs_size_t bytesToXfer;	/* # bytes to xfer */
    afs_size_t bytesXferred;	/* # bytes actually xferred */
    struct afs_stats_AccessInfo *accP;	/*Ptr to access record in stats */
    int fromReplica;		/*Are we reading from a replica? */
    int numFetchLoops;		/*# times around the fetch/analyze loop */
#endif /* AFS_NOSTATS */

    AFS_STATCNT(afs_GetDCache);

    if (dcacheDisabled)
	return NULL;

    setLocks = aflags & 1;

    /*
     * Determine the chunk number and offset within the chunk corresponding
     * to the desired byte.
     */
    if (avc->fid.Fid.Vnode & 1) {	/* if (vType(avc) == VDIR) */
	chunk = 0;
    } else {
	chunk = AFS_CHUNK(abyte);
    }

    /* come back to here if we waited for the cache to drain. */
  RetryGetDCache:

    setNewCallback = setVcacheStatus = 0;

    if (setLocks) {
	if (slowPass)
	    ObtainWriteLock(&avc->lock, 616);
	else
	    ObtainReadLock(&avc->lock);
    }

    /*
     * Locks held:
     * avc->lock(R) if setLocks && !slowPass
     * avc->lock(W) if !setLocks || slowPass
     */

    shortcut = 0;

    /* check hints first! (might could use bcmp or some such...) */
    if ((tdc = avc->h1.dchint)) {
	int dcLocked;

	/*
	 * The locking order between afs_xdcache and dcache lock matters.
	 * The hint dcache entry could be anywhere, even on the free list.
	 * Locking afs_xdcache ensures that noone is trying to pull dcache
	 * entries from the free list, and thereby assuming them to be not
	 * referenced and not locked.
	 */
	MObtainReadLock(&afs_xdcache);
	dcLocked = (0 == NBObtainSharedLock(&tdc->lock, 601));

	if (dcLocked && (tdc->index != NULLIDX)
	    && !FidCmp(&tdc->f.fid, &avc->fid) && chunk == tdc->f.chunk
	    && !(afs_indexFlags[tdc->index] & (IFFree | IFDiscarded))) {
	    /* got the right one.  It might not be the right version, and it 
	     * might be fetching, but it's the right dcache entry.
	     */
	    /* All this code should be integrated better with what follows:
	     * I can save a good bit more time under a write lock if I do..
	     */
	    ObtainWriteLock(&tdc->tlock, 603);
	    tdc->refCount++;
	    ReleaseWriteLock(&tdc->tlock);

	    MReleaseReadLock(&afs_xdcache);
	    shortcut = 1;

	    if (hsame(tdc->f.versionNo, avc->m.DataVersion)
		&& !(tdc->dflags & DFFetching)) {

		afs_stats_cmperf.dcacheHits++;
		MObtainWriteLock(&afs_xdcache, 559);
		QRemove(&tdc->lruq);
		QAdd(&afs_DLRU, &tdc->lruq);
		MReleaseWriteLock(&afs_xdcache);

		/* Locks held:
		 * avc->lock(R) if setLocks && !slowPass
		 * avc->lock(W) if !setLocks || slowPass
		 * tdc->lock(S)
		 */
		goto done;
	    }
	} else {
	    if (dcLocked)
		ReleaseSharedLock(&tdc->lock);
	    MReleaseReadLock(&afs_xdcache);
	}

	if (!shortcut)
	    tdc = 0;
    }

    /* Locks held:
     * avc->lock(R) if setLocks && !slowPass
     * avc->lock(W) if !setLocks || slowPass
     * tdc->lock(S) if tdc
     */

    if (!tdc) {			/* If the hint wasn't the right dcache entry */
	/*
	 * Hash on the [fid, chunk] and get the corresponding dcache index
	 * after write-locking the dcache.
	 */
      RetryLookup:

	/* Locks held:
	 * avc->lock(R) if setLocks && !slowPass
	 * avc->lock(W) if !setLocks || slowPass
	 */

	i = DCHash(&avc->fid, chunk);
	/* check to make sure our space is fine */
	afs_MaybeWakeupTruncateDaemon();

	MObtainWriteLock(&afs_xdcache, 280);
	us = NULLIDX;
	for (index = afs_dchashTbl[i]; index != NULLIDX;) {
	    if (afs_indexUnique[index] == avc->fid.Fid.Unique) {
		tdc = afs_GetDSlot(index, NULL);
		ReleaseReadLock(&tdc->tlock);
		/*
		 * Locks held:
		 * avc->lock(R) if setLocks && !slowPass
		 * avc->lock(W) if !setLocks || slowPass
		 * afs_xdcache(W)
		 */
		if (!FidCmp(&tdc->f.fid, &avc->fid) && chunk == tdc->f.chunk) {
		    /* Move it up in the beginning of the list */
		    if (afs_dchashTbl[i] != index) {
			afs_dcnextTbl[us] = afs_dcnextTbl[index];
			afs_dcnextTbl[index] = afs_dchashTbl[i];
			afs_dchashTbl[i] = index;
		    }
		    MReleaseWriteLock(&afs_xdcache);
		    ObtainSharedLock(&tdc->lock, 606);
		    break;	/* leaving refCount high for caller */
		}
		afs_PutDCache(tdc);
		tdc = 0;
	    }
	    us = index;
	    index = afs_dcnextTbl[index];
	}

	/*
	 * If we didn't find the entry, we'll create one.
	 */
	if (index == NULLIDX) {
	    /*
	     * Locks held:
	     * avc->lock(R) if setLocks
	     * avc->lock(W) if !setLocks
	     * afs_xdcache(W)
	     */
	    afs_Trace2(afs_iclSetp, CM_TRACE_GETDCACHE1, ICL_TYPE_POINTER,
		       avc, ICL_TYPE_INT32, chunk);

	    /* Make sure there is a free dcache entry for us to use */
	    if (afs_discardDCList == NULLIDX && afs_freeDCList == NULLIDX) {
		while (1) {
		    if (!setLocks)
			avc->states |= CDCLock;
		    afs_GetDownD(5, (int *)0);	/* just need slots */
		    if (!setLocks)
			avc->states &= ~CDCLock;
		    if (afs_discardDCList != NULLIDX
			|| afs_freeDCList != NULLIDX)
			break;
		    /* If we can't get space for 5 mins we give up and panic */
		    if (++downDCount > 300)
			osi_Panic("getdcache");
		    MReleaseWriteLock(&afs_xdcache);
		    /*
		     * Locks held:
		     * avc->lock(R) if setLocks
		     * avc->lock(W) if !setLocks
		     */
		    afs_osi_Wait(1000, 0, 0);
		    goto RetryLookup;
		}
	    }

	    if (afs_discardDCList == NULLIDX
		|| ((aflags & 2) && afs_freeDCList != NULLIDX)) {

		afs_indexFlags[afs_freeDCList] &= ~IFFree;
		tdc = afs_GetDSlot(afs_freeDCList, 0);
		osi_Assert(tdc->refCount == 1);
		ReleaseReadLock(&tdc->tlock);
		ObtainWriteLock(&tdc->lock, 604);
		afs_freeDCList = afs_dvnextTbl[tdc->index];
		afs_freeDCCount--;
	    } else {
		afs_indexFlags[afs_discardDCList] &= ~IFDiscarded;
		tdc = afs_GetDSlot(afs_discardDCList, 0);
		osi_Assert(tdc->refCount == 1);
		ReleaseReadLock(&tdc->tlock);
		ObtainWriteLock(&tdc->lock, 605);
		afs_discardDCList = afs_dvnextTbl[tdc->index];
		afs_discardDCCount--;
		size =
		    ((tdc->f.chunkBytes +
		      afs_fsfragsize) ^ afs_fsfragsize) >> 10;
		afs_blocksDiscarded -= size;
		afs_stats_cmperf.cacheBlocksDiscarded = afs_blocksDiscarded;
		if (aflags & 2) {
		    /* Truncate the chunk so zeroes get filled properly */
		    file = afs_CFileOpen(tdc->f.inode);
		    afs_CFileTruncate(file, 0);
		    afs_CFileClose(file);
		    afs_AdjustSize(tdc, 0);
		}
	    }

	    /*
	     * Locks held:
	     * avc->lock(R) if setLocks
	     * avc->lock(W) if !setLocks
	     * tdc->lock(W)
	     * afs_xdcache(W)
	     */

	    /*
	     * Fill in the newly-allocated dcache record.
	     */
	    afs_indexFlags[tdc->index] &= ~(IFDirtyPages | IFAnyPages);
	    tdc->f.fid = avc->fid;
	    afs_indexUnique[tdc->index] = tdc->f.fid.Fid.Unique;
	    hones(tdc->f.versionNo);	/* invalid value */
	    tdc->f.chunk = chunk;
	    tdc->validPos = AFS_CHUNKTOBASE(chunk);
	    /* XXX */
	    if (tdc->lruq.prev == &tdc->lruq)
		osi_Panic("lruq 1");

	    /*
	     * Now add to the two hash chains - note that i is still set
	     * from the above DCHash call.
	     */
	    afs_dcnextTbl[tdc->index] = afs_dchashTbl[i];
	    afs_dchashTbl[i] = tdc->index;
	    i = DVHash(&avc->fid);
	    afs_dvnextTbl[tdc->index] = afs_dvhashTbl[i];
	    afs_dvhashTbl[i] = tdc->index;
	    tdc->dflags = DFEntryMod;
	    tdc->mflags = 0;
	    tdc->f.states = 0;
	    afs_MaybeWakeupTruncateDaemon();
	    MReleaseWriteLock(&afs_xdcache);
	    ConvertWToSLock(&tdc->lock);
	}
    }


    /* vcache->dcache hint failed */
    /*
     * Locks held:
     * avc->lock(R) if setLocks && !slowPass
     * avc->lock(W) if !setLocks || slowPass
     * tdc->lock(S)
     */
    afs_Trace4(afs_iclSetp, CM_TRACE_GETDCACHE2, ICL_TYPE_POINTER, avc,
	       ICL_TYPE_POINTER, tdc, ICL_TYPE_INT32,
	       hgetlo(tdc->f.versionNo), ICL_TYPE_INT32,
	       hgetlo(avc->m.DataVersion));
    /*
     * Here we have the entry in tdc, with its refCount incremented.
     * Note: we don't use the S-lock on avc; it costs concurrency when
     * storing a file back to the server.
     */

    /*
     * Not a newly created file so we need to check the file's length and
     * compare data versions since someone could have changed the data or we're
     * reading a file written elsewhere. We only want to bypass doing no-op
     * read rpcs on newly created files (dv of 0) since only then we guarantee
     * that this chunk's data hasn't been filled by another client.
     */
    size = AFS_CHUNKSIZE(abyte);
    if (aflags & 4)		/* called from write */
	tlen = *alen;
    else			/* called from read */
	tlen = tdc->validPos - abyte;
    Position = AFS_CHUNKTOBASE(chunk);
    afs_Trace4(afs_iclSetp, CM_TRACE_GETDCACHE3, ICL_TYPE_INT32, tlen,
	       ICL_TYPE_INT32, aflags, ICL_TYPE_OFFSET,
	       ICL_HANDLE_OFFSET(abyte), ICL_TYPE_OFFSET,
	       ICL_HANDLE_OFFSET(Position));
    if ((aflags & 4) && (hiszero(avc->m.DataVersion)))
	doAdjustSize = 1;
    if ((aflags & 4) && (abyte == Position) && (tlen >= size))
	overWriteWholeChunk = 1;
    if (doAdjustSize || overWriteWholeChunk) {
#if	defined(AFS_AIX32_ENV) || defined(AFS_SGI_ENV)
#ifdef	AFS_SGI_ENV
#ifdef AFS_SGI64_ENV
	if (doAdjustSize)
	    adjustsize = NBPP;
#else /* AFS_SGI64_ENV */
	if (doAdjustSize)
	    adjustsize = 8192;
#endif /* AFS_SGI64_ENV */
#else /* AFS_SGI_ENV */
	if (doAdjustSize)
	    adjustsize = 4096;
#endif /* AFS_SGI_ENV */
	if (AFS_CHUNKTOBASE(chunk) + adjustsize >= avc->m.Length &&
#else /* defined(AFS_AIX32_ENV) || defined(AFS_SGI_ENV) */
#if	defined(AFS_SUN_ENV)  || defined(AFS_OSF_ENV)
	if ((doAdjustSize || (AFS_CHUNKTOBASE(chunk) >= avc->m.Length)) &&
#else
	if (AFS_CHUNKTOBASE(chunk) >= avc->m.Length &&
#endif
#endif /* defined(AFS_AIX32_ENV) || defined(AFS_SGI_ENV) */
	    !hsame(avc->m.DataVersion, tdc->f.versionNo))
	    doReallyAdjustSize = 1;

	if (doReallyAdjustSize || overWriteWholeChunk) {
	    /* no data in file to read at this position */
	    UpgradeSToWLock(&tdc->lock, 607);

	    file = afs_CFileOpen(tdc->f.inode);
	    afs_CFileTruncate(file, 0);
	    afs_CFileClose(file);
	    afs_AdjustSize(tdc, 0);
	    hset(tdc->f.versionNo, avc->m.DataVersion);
	    tdc->dflags |= DFEntryMod;

	    ConvertWToSLock(&tdc->lock);
	}
    }

    /*
     * We must read in the whole chunk if the version number doesn't
     * match.
     */
    if (aflags & 2) {
	/* don't need data, just a unique dcache entry */
	ObtainWriteLock(&afs_xdcache, 608);
	hset(afs_indexTimes[tdc->index], afs_indexCounter);
	hadd32(afs_indexCounter, 1);
	ReleaseWriteLock(&afs_xdcache);

	updateV2DC(setLocks, avc, tdc, 553);
	if (vType(avc) == VDIR)
	    *aoffset = abyte;
	else
	    *aoffset = AFS_CHUNKOFFSET(abyte);
	if (tdc->validPos < abyte)
	    *alen = (afs_size_t) 0;
	else
	    *alen = tdc->validPos - abyte;
	ReleaseSharedLock(&tdc->lock);
	if (setLocks) {
	    if (slowPass)
		ReleaseWriteLock(&avc->lock);
	    else
		ReleaseReadLock(&avc->lock);
	}
	return tdc;		/* check if we're done */
    }

    /*
     * Locks held:
     * avc->lock(R) if setLocks && !slowPass
     * avc->lock(W) if !setLocks || slowPass
     * tdc->lock(S)
     */
    osi_Assert((setLocks && !slowPass) || WriteLocked(&avc->lock));

    setNewCallback = setVcacheStatus = 0;

    /*
     * Locks held:
     * avc->lock(R) if setLocks && !slowPass
     * avc->lock(W) if !setLocks || slowPass
     * tdc->lock(S)
     */
    if (!hsame(avc->m.DataVersion, tdc->f.versionNo) && !overWriteWholeChunk) {
	/*
	 * Version number mismatch.
	 */
	UpgradeSToWLock(&tdc->lock, 609);

	/*
	 * If data ever existed for this vnode, and this is a text object,
	 * do some clearing.  Now, you'd think you need only do the flush
	 * when VTEXT is on, but VTEXT is turned off when the text object
	 * is freed, while pages are left lying around in memory marked
	 * with this vnode.  If we would reactivate (create a new text
	 * object from) this vnode, we could easily stumble upon some of
	 * these old pages in pagein.  So, we always flush these guys.
	 * Sun has a wonderful lack of useful invariants in this system.
	 *
	 * avc->flushDV is the data version # of the file at the last text
	 * flush.  Clearly, at least, we don't have to flush the file more
	 * often than it changes
	 */
	if (hcmp(avc->flushDV, avc->m.DataVersion) < 0) {
	    /*
	     * By here, the cache entry is always write-locked.  We can
	     * deadlock if we call osi_Flush with the cache entry locked...
	     * Unlock the dcache too.
	     */
	    ReleaseWriteLock(&tdc->lock);
	    if (setLocks && !slowPass)
		ReleaseReadLock(&avc->lock);
	    else
		ReleaseWriteLock(&avc->lock);

	    osi_FlushText(avc);
	    /*
	     * Call osi_FlushPages in open, read/write, and map, since it
	     * is too hard here to figure out if we should lock the
	     * pvnLock.
	     */
	    if (setLocks && !slowPass)
		ObtainReadLock(&avc->lock);
	    else
		ObtainWriteLock(&avc->lock, 66);
	    ObtainWriteLock(&tdc->lock, 610);
	}

	/*
	 * Locks held:
	 * avc->lock(R) if setLocks && !slowPass
	 * avc->lock(W) if !setLocks || slowPass
	 * tdc->lock(W)
	 */

	/* Watch for standard race condition around osi_FlushText */
	if (hsame(avc->m.DataVersion, tdc->f.versionNo)) {
	    updateV2DC(setLocks, avc, tdc, 569);	/* set hint */
	    afs_stats_cmperf.dcacheHits++;
	    ConvertWToSLock(&tdc->lock);
	    goto done;
	}

	/* Sleep here when cache needs to be drained. */
	if (setLocks && !slowPass
	    && (afs_blocksUsed >
		(CM_WAITFORDRAINPCT * afs_cacheBlocks) / 100)) {
	    /* Make sure truncate daemon is running */
	    afs_MaybeWakeupTruncateDaemon();
	    ObtainWriteLock(&tdc->tlock, 614);
	    tdc->refCount--;	/* we'll re-obtain the dcache when we re-try. */
	    ReleaseWriteLock(&tdc->tlock);
	    ReleaseWriteLock(&tdc->lock);
	    ReleaseReadLock(&avc->lock);
	    while ((afs_blocksUsed - afs_blocksDiscarded) >
		   (CM_WAITFORDRAINPCT * afs_cacheBlocks) / 100) {
		afs_WaitForCacheDrain = 1;
		afs_osi_Sleep(&afs_WaitForCacheDrain);
	    }
	    afs_MaybeFreeDiscardedDCache();
	    /* need to check if someone else got the chunk first. */
	    goto RetryGetDCache;
	}

	/* Do not fetch data beyond truncPos. */
	maxGoodLength = avc->m.Length;
	if (avc->truncPos < maxGoodLength)
	    maxGoodLength = avc->truncPos;
	Position = AFS_CHUNKBASE(abyte);
	if (vType(avc) == VDIR) {
	    size = avc->m.Length;
	    if (size > tdc->f.chunkBytes) {
		/* pre-reserve space for file */
		afs_AdjustSize(tdc, size);
	    }
	    size = 999999999;	/* max size for transfer */
	} else {
	    size = AFS_CHUNKSIZE(abyte);	/* expected max size */
	    /* don't read past end of good data on server */
	    if (Position + size > maxGoodLength)
		size = maxGoodLength - Position;
	    if (size < 0)
		size = 0;	/* Handle random races */
	    if (size > tdc->f.chunkBytes) {
		/* pre-reserve space for file */
		afs_AdjustSize(tdc, size);	/* changes chunkBytes */
		/* max size for transfer still in size */
	    }
	}
	if (afs_mariner && !tdc->f.chunk)
	    afs_MarinerLog("fetch$Fetching", avc);	/* , Position, size, afs_indexCounter ); */
	/*
	 * Right now, we only have one tool, and it's a hammer.  So, we
	 * fetch the whole file.
	 */
	DZap(&tdc->f.inode);	/* pages in cache may be old */
#ifdef  IHINT
	if (file = tdc->ihint) {
	    if (tdc->f.inode == file->inum)
		usedihint++;
	    else {
		tdc->ihint = 0;
		afs_UFSClose(file);
		file = 0;
		nihints--;
		file = osi_UFSOpen(tdc->f.inode);
	    }
	} else
#endif /* IHINT */
	    file = afs_CFileOpen(tdc->f.inode);
	afs_RemoveVCB(&avc->fid);
	tdc->f.states |= DWriting;
	tdc->dflags |= DFFetching;
	tdc->validPos = Position;	/*  which is AFS_CHUNKBASE(abyte) */
	if (tdc->mflags & DFFetchReq) {
	    tdc->mflags &= ~DFFetchReq;
	    if (afs_osi_Wakeup(&tdc->validPos) == 0)
		afs_Trace4(afs_iclSetp, CM_TRACE_DCACHEWAKE, ICL_TYPE_STRING,
			   __FILE__, ICL_TYPE_INT32, __LINE__,
			   ICL_TYPE_POINTER, tdc, ICL_TYPE_INT32,
			   tdc->dflags);
	}
	tsmall =
	    (struct tlocal1 *)osi_AllocLargeSpace(sizeof(struct tlocal1));
	setVcacheStatus = 0;
#ifndef AFS_NOSTATS
	/*
	 * Remember if we are doing the reading from a replicated volume,
	 * and how many times we've zipped around the fetch/analyze loop.
	 */
	fromReplica = (avc->states & CRO) ? 1 : 0;
	numFetchLoops = 0;
	accP = &(afs_stats_cmfullperf.accessinf);
	if (fromReplica)
	    (accP->replicatedRefs)++;
	else
	    (accP->unreplicatedRefs)++;
#endif /* AFS_NOSTATS */
	/* this is a cache miss */
	afs_Trace4(afs_iclSetp, CM_TRACE_FETCHPROC, ICL_TYPE_POINTER, avc,
		   ICL_TYPE_FID, &(avc->fid), ICL_TYPE_OFFSET,
		   ICL_HANDLE_OFFSET(Position), ICL_TYPE_INT32, size);

	if (size)
	    afs_stats_cmperf.dcacheMisses++;
	code = 0;
	/*
	 * Dynamic root support:  fetch data from local memory.
	 */
	if (afs_IsDynroot(avc)) {
	    char *dynrootDir;
	    int dynrootLen;

	    afs_GetDynroot(&dynrootDir, &dynrootLen, &tsmall->OutStatus);

	    dynrootDir += Position;
	    dynrootLen -= Position;
	    if (size > dynrootLen)
		size = dynrootLen;
	    if (size < 0)
		size = 0;
	    code = afs_CFileWrite(file, 0, dynrootDir, size);
	    afs_PutDynroot();

	    if (code == size)
		code = 0;
	    else
		code = -1;

	    tdc->validPos = Position + size;
	    afs_CFileTruncate(file, size);	/* prune it */
	} else
	    /*
	     * Not a dynamic vnode:  do the real fetch.
	     */
	    do {
		/*
		 * Locks held:
		 * avc->lock(R) if setLocks && !slowPass
		 * avc->lock(W) if !setLocks || slowPass
		 * tdc->lock(W)
		 */

		tc = afs_Conn(&avc->fid, areq, SHARED_LOCK);
		if (tc) {
		    afs_int32 length_hi, length, bytes;
#ifndef AFS_NOSTATS
		    numFetchLoops++;
		    if (fromReplica)
			(accP->numReplicasAccessed)++;

#endif /* AFS_NOSTATS */
		    if (!setLocks || slowPass) {
			avc->callback = tc->srvr->server;
		    } else {
			newCallback = tc->srvr->server;
			setNewCallback = 1;
		    }
		    i = osi_Time();
		    RX_AFS_GUNLOCK();
		    tcall = rx_NewCall(tc->id);
		    RX_AFS_GLOCK();

		    XSTATS_START_TIME(AFS_STATS_FS_RPCIDX_FETCHDATA);
#ifdef AFS_64BIT_CLIENT
		    length_hi = code = 0;
		    if (!afs_serverHasNo64Bit(tc)) {
			tsize = size;
			RX_AFS_GUNLOCK();
			code =
			    StartRXAFS_FetchData64(tcall,
						   (struct AFSFid *)&avc->fid.
						   Fid, Position, tsize);
			if (code != 0) {
			    RX_AFS_GLOCK();
			    afs_Trace2(afs_iclSetp, CM_TRACE_FETCH64CODE,
				       ICL_TYPE_POINTER, avc, ICL_TYPE_INT32,
				       code);
			} else {
			    bytes =
				rx_Read(tcall, (char *)&length_hi,
					sizeof(afs_int32));
			    RX_AFS_GLOCK();
			    if (bytes == sizeof(afs_int32)) {
				length_hi = ntohl(length_hi);
			    } else {
				length_hi = 0;
				code = rx_Error(tcall);
				RX_AFS_GUNLOCK();
				code1 = rx_EndCall(tcall, code);
				RX_AFS_GLOCK();
				tcall = (struct rx_call *)0;
			    }
			}
		    }
		    if (code == RXGEN_OPCODE || afs_serverHasNo64Bit(tc)) {
			if (Position > 0x7FFFFFFF) {
			    code = EFBIG;
			} else {
			    afs_int32 pos;
			    pos = Position;
			    RX_AFS_GUNLOCK();
			    if (!tcall)
				tcall = rx_NewCall(tc->id);
			    code =
				StartRXAFS_FetchData(tcall, (struct AFSFid *)
						     &avc->fid.Fid, pos,
						     size);
			    RX_AFS_GLOCK();
			}
			afs_serverSetNo64Bit(tc);
		    }
		    if (code == 0) {
			RX_AFS_GUNLOCK();
			bytes =
			    rx_Read(tcall, (char *)&length,
				    sizeof(afs_int32));
			RX_AFS_GLOCK();
			if (bytes == sizeof(afs_int32)) {
			    length = ntohl(length);
			} else {
			    code = rx_Error(tcall);
			}
		    }
		    FillInt64(lengthFound, length_hi, length);
		    afs_Trace3(afs_iclSetp, CM_TRACE_FETCH64LENG,
			       ICL_TYPE_POINTER, avc, ICL_TYPE_INT32, code,
			       ICL_TYPE_OFFSET,
			       ICL_HANDLE_OFFSET(lengthFound));
#else /* AFS_64BIT_CLIENT */
		    RX_AFS_GUNLOCK();
		    code =
			StartRXAFS_FetchData(tcall,
					     (struct AFSFid *)&avc->fid.Fid,
					     Position, size);
		    RX_AFS_GLOCK();
		    if (code == 0) {
			RX_AFS_GUNLOCK();
			bytes =
			    rx_Read(tcall, (char *)&length,
				    sizeof(afs_int32));
			RX_AFS_GLOCK();
			if (bytes == sizeof(afs_int32)) {
			    length = ntohl(length);
			} else {
			    code = rx_Error(tcall);
			}
		    }
#endif /* AFS_64BIT_CLIENT */
		    if (code == 0) {

#ifndef AFS_NOSTATS
			xferP =
			    &(afs_stats_cmfullperf.rpc.
			      fsXferTimes[AFS_STATS_FS_XFERIDX_FETCHDATA]);
			osi_GetuTime(&xferStartTime);

			code =
			    afs_CacheFetchProc(tcall, file,
					       (afs_size_t) Position, tdc,
					       avc, &bytesToXfer,
					       &bytesXferred, length);

			osi_GetuTime(&xferStopTime);
			(xferP->numXfers)++;
			if (!code) {
			    (xferP->numSuccesses)++;
			    afs_stats_XferSumBytes
				[AFS_STATS_FS_XFERIDX_FETCHDATA] +=
				bytesXferred;
			    (xferP->sumBytes) +=
				(afs_stats_XferSumBytes
				 [AFS_STATS_FS_XFERIDX_FETCHDATA] >> 10);
			    afs_stats_XferSumBytes
				[AFS_STATS_FS_XFERIDX_FETCHDATA] &= 0x3FF;
			    if (bytesXferred < xferP->minBytes)
				xferP->minBytes = bytesXferred;
			    if (bytesXferred > xferP->maxBytes)
				xferP->maxBytes = bytesXferred;

			    /*
			     * Tally the size of the object.  Note: we tally the actual size,
			     * NOT the number of bytes that made it out over the wire.
			     */
			    if (bytesToXfer <= AFS_STATS_MAXBYTES_BUCKET0)
				(xferP->count[0])++;
			    else if (bytesToXfer <=
				     AFS_STATS_MAXBYTES_BUCKET1)
				(xferP->count[1])++;
			    else if (bytesToXfer <=
				     AFS_STATS_MAXBYTES_BUCKET2)
				(xferP->count[2])++;
			    else if (bytesToXfer <=
				     AFS_STATS_MAXBYTES_BUCKET3)
				(xferP->count[3])++;
			    else if (bytesToXfer <=
				     AFS_STATS_MAXBYTES_BUCKET4)
				(xferP->count[4])++;
			    else if (bytesToXfer <=
				     AFS_STATS_MAXBYTES_BUCKET5)
				(xferP->count[5])++;
			    else if (bytesToXfer <=
				     AFS_STATS_MAXBYTES_BUCKET6)
				(xferP->count[6])++;
			    else if (bytesToXfer <=
				     AFS_STATS_MAXBYTES_BUCKET7)
				(xferP->count[7])++;
			    else
				(xferP->count[8])++;

			    afs_stats_GetDiff(elapsedTime, xferStartTime,
					      xferStopTime);
			    afs_stats_AddTo((xferP->sumTime), elapsedTime);
			    afs_stats_SquareAddTo((xferP->sqrTime),
						  elapsedTime);
			    if (afs_stats_TimeLessThan
				(elapsedTime, (xferP->minTime))) {
				afs_stats_TimeAssign((xferP->minTime),
						     elapsedTime);
			    }
			    if (afs_stats_TimeGreaterThan
				(elapsedTime, (xferP->maxTime))) {
				afs_stats_TimeAssign((xferP->maxTime),
						     elapsedTime);
			    }
			}
#else
			code =
			    afs_CacheFetchProc(tcall, file, Position, tdc,
					       avc, 0, 0, length);
#endif /* AFS_NOSTATS */
		    }
		    if (code == 0) {
			RX_AFS_GUNLOCK();
			code =
			    EndRXAFS_FetchData(tcall, &tsmall->OutStatus,
					       &tsmall->CallBack,
					       &tsmall->tsync);
			RX_AFS_GLOCK();
		    }
		    XSTATS_END_TIME;
		    RX_AFS_GUNLOCK();
		    if (tcall)
			code1 = rx_EndCall(tcall, code);
		    RX_AFS_GLOCK();
		} else {
		    code = -1;
		}
		if (!code && code1)
		    code = code1;

		if (code == 0) {
		    /* callback could have been broken (or expired) in a race here, 
		     * but we return the data anyway.  It's as good as we knew about
		     * when we started. */
		    /* 
		     * validPos is updated by CacheFetchProc, and can only be 
		     * modifed under a dcache write lock, which we've blocked out 
		     */
		    size = tdc->validPos - Position;	/* actual segment size */
		    if (size < 0)
			size = 0;
		    afs_CFileTruncate(file, size);	/* prune it */
		} else {
		    if (!setLocks || slowPass) {
			ObtainWriteLock(&afs_xcbhash, 453);
			afs_DequeueCallback(avc);
			avc->states &= ~(CStatd | CUnique);
			avc->callback = NULL;
			ReleaseWriteLock(&afs_xcbhash);
			if (avc->fid.Fid.Vnode & 1 || (vType(avc) == VDIR))
			    osi_dnlc_purgedp(avc);
		    } else {
			/* Something lost.  Forget about performance, and go
			 * back with a vcache write lock.
			 */
			afs_CFileTruncate(file, 0);
			afs_AdjustSize(tdc, 0);
			afs_CFileClose(file);
			osi_FreeLargeSpace(tsmall);
			tsmall = 0;
			ReleaseWriteLock(&tdc->lock);
			afs_PutDCache(tdc);
			tdc = 0;
			ReleaseReadLock(&avc->lock);
			slowPass = 1;
			goto RetryGetDCache;
		    }
		}

	    } while (afs_Analyze
		     (tc, code, &avc->fid, areq,
		      AFS_STATS_FS_RPCIDX_FETCHDATA, SHARED_LOCK, NULL));

	/*
	 * Locks held:
	 * avc->lock(R) if setLocks && !slowPass
	 * avc->lock(W) if !setLocks || slowPass
	 * tdc->lock(W)
	 */

#ifndef AFS_NOSTATS
	/*
	 * In the case of replicated access, jot down info on the number of
	 * attempts it took before we got through or gave up.
	 */
	if (fromReplica) {
	    if (numFetchLoops <= 1)
		(accP->refFirstReplicaOK)++;
	    if (numFetchLoops > accP->maxReplicasPerRef)
		accP->maxReplicasPerRef = numFetchLoops;
	}
#endif /* AFS_NOSTATS */

	tdc->dflags &= ~DFFetching;
	if (afs_osi_Wakeup(&tdc->validPos) == 0)
	    afs_Trace4(afs_iclSetp, CM_TRACE_DCACHEWAKE, ICL_TYPE_STRING,
		       __FILE__, ICL_TYPE_INT32, __LINE__, ICL_TYPE_POINTER,
		       tdc, ICL_TYPE_INT32, tdc->dflags);
	if (avc->execsOrWriters == 0)
	    tdc->f.states &= ~DWriting;

	/* now, if code != 0, we have an error and should punt.
	 * note that we have the vcache write lock, either because
	 * !setLocks or slowPass.
	 */
	if (code) {
	    afs_CFileTruncate(file, 0);
	    afs_AdjustSize(tdc, 0);
	    afs_CFileClose(file);
	    ZapDCE(tdc);	/* sets DFEntryMod */
	    if (vType(avc) == VDIR) {
		DZap(&tdc->f.inode);
	    }
	    ReleaseWriteLock(&tdc->lock);
	    afs_PutDCache(tdc);
	    ObtainWriteLock(&afs_xcbhash, 454);
	    afs_DequeueCallback(avc);
	    avc->states &= ~(CStatd | CUnique);
	    ReleaseWriteLock(&afs_xcbhash);
	    if (avc->fid.Fid.Vnode & 1 || (vType(avc) == VDIR))
		osi_dnlc_purgedp(avc);
	    /*
	     * Locks held:
	     * avc->lock(W); assert(!setLocks || slowPass)
	     */
	    osi_Assert(!setLocks || slowPass);
	    tdc = NULL;
	    goto done;
	}

	/* otherwise we copy in the just-fetched info */
	afs_CFileClose(file);
	afs_AdjustSize(tdc, size);	/* new size */
	/*
	 * Copy appropriate fields into vcache.  Status is
	 * copied later where we selectively acquire the
	 * vcache write lock.
	 */
	if (slowPass)
	    afs_ProcessFS(avc, &tsmall->OutStatus, areq);
	else
	    setVcacheStatus = 1;
	hset64(tdc->f.versionNo, tsmall->OutStatus.dataVersionHigh,
	       tsmall->OutStatus.DataVersion);
	tdc->dflags |= DFEntryMod;
	afs_indexFlags[tdc->index] |= IFEverUsed;
	ConvertWToSLock(&tdc->lock);
    } /*Data version numbers don't match */
    else {
	/*
	 * Data version numbers match.
	 */
	afs_stats_cmperf.dcacheHits++;
    }				/*Data version numbers match */

    updateV2DC(setLocks, avc, tdc, 335);	/* set hint */
  done:
    /*
     * Locks held:
     * avc->lock(R) if setLocks && !slowPass
     * avc->lock(W) if !setLocks || slowPass
     * tdc->lock(S) if tdc
     */

    /*
     * See if this was a reference to a file in the local cell.
     */
    if (afs_IsPrimaryCellNum(avc->fid.Cell))
	afs_stats_cmperf.dlocalAccesses++;
    else
	afs_stats_cmperf.dremoteAccesses++;

    /* Fix up LRU info */

    if (tdc) {
	MObtainWriteLock(&afs_xdcache, 602);
	hset(afs_indexTimes[tdc->index], afs_indexCounter);
	hadd32(afs_indexCounter, 1);
	MReleaseWriteLock(&afs_xdcache);

	/* return the data */
	if (vType(avc) == VDIR)
	    *aoffset = abyte;
	else
	    *aoffset = AFS_CHUNKOFFSET(abyte);
	*alen = (tdc->f.chunkBytes - *aoffset);
	ReleaseSharedLock(&tdc->lock);
    }

    /*
     * Locks held:
     * avc->lock(R) if setLocks && !slowPass
     * avc->lock(W) if !setLocks || slowPass
     */

    /* Fix up the callback and status values in the vcache */
    doVcacheUpdate = 0;
    if (setLocks && !slowPass) {
	/* DCLOCKXXX
	 *
	 * This is our dirty little secret to parallel fetches.
	 * We don't write-lock the vcache while doing the fetch,
	 * but potentially we'll need to update the vcache after
	 * the fetch is done.
	 *
	 * Drop the read lock and try to re-obtain the write
	 * lock.  If the vcache still has the same DV, it's
	 * ok to go ahead and install the new data.
	 */
	afs_hyper_t currentDV, statusDV;

	hset(currentDV, avc->m.DataVersion);

	if (setNewCallback && avc->callback != newCallback)
	    doVcacheUpdate = 1;

	if (tsmall) {
	    hset64(statusDV, tsmall->OutStatus.dataVersionHigh,
		   tsmall->OutStatus.DataVersion);

	    if (setVcacheStatus && avc->m.Length != tsmall->OutStatus.Length)
		doVcacheUpdate = 1;
	    if (setVcacheStatus && !hsame(currentDV, statusDV))
		doVcacheUpdate = 1;
	}

	ReleaseReadLock(&avc->lock);

	if (doVcacheUpdate) {
	    ObtainWriteLock(&avc->lock, 615);
	    if (!hsame(avc->m.DataVersion, currentDV)) {
		/* We lose.  Someone will beat us to it. */
		doVcacheUpdate = 0;
		ReleaseWriteLock(&avc->lock);
	    }
	}
    }

    /* With slow pass, we've already done all the updates */
    if (slowPass) {
	ReleaseWriteLock(&avc->lock);
    }

    /* Check if we need to perform any last-minute fixes with a write-lock */
    if (!setLocks || doVcacheUpdate) {
	if (setNewCallback)
	    avc->callback = newCallback;
	if (tsmall && setVcacheStatus)
	    afs_ProcessFS(avc, &tsmall->OutStatus, areq);
	if (setLocks)
	    ReleaseWriteLock(&avc->lock);
    }

    if (tsmall)
	osi_FreeLargeSpace(tsmall);

    return tdc;
}				/*afs_GetDCache */


/*
 * afs_WriteThroughDSlots
 *
 * Description:
 *	Sweep through the dcache slots and write out any modified
 *	in-memory data back on to our caching store.
 *
 * Parameters:
 *	None.
 *
 * Environment:
 *	The afs_xdcache is write-locked through this whole affair.
 */
void
afs_WriteThroughDSlots(void)
{
    register struct dcache *tdc;
    register afs_int32 i, touchedit = 0;

    struct afs_q DirtyQ, *tq;

    AFS_STATCNT(afs_WriteThroughDSlots);

    /*
     * Because of lock ordering, we can't grab dcache locks while
     * holding afs_xdcache.  So we enter xdcache, get a reference
     * for every dcache entry, and exit xdcache.
     */
    MObtainWriteLock(&afs_xdcache, 283);
    QInit(&DirtyQ);
    for (i = 0; i < afs_cacheFiles; i++) {
	tdc = afs_indexTable[i];

	/* Grab tlock in case the existing refcount isn't zero */
	if (tdc && !(afs_indexFlags[i] & (IFFree | IFDiscarded))) {
	    ObtainWriteLock(&tdc->tlock, 623);
	    tdc->refCount++;
	    ReleaseWriteLock(&tdc->tlock);

	    QAdd(&DirtyQ, &tdc->dirty);
	}
    }
    MReleaseWriteLock(&afs_xdcache);

    /*
     * Now, for each dcache entry we found, check if it's dirty.
     * If so, get write-lock, get afs_xdcache, which protects
     * afs_cacheInodep, and flush it.  Don't forget to put back
     * the refcounts.
     */

#define DQTODC(q)	((struct dcache *)(((char *) (q)) - sizeof(struct afs_q)))

    for (tq = DirtyQ.prev; tq != &DirtyQ; tq = QPrev(tq)) {
        tdc = DQTODC(tq);
	if (tdc->dflags & DFEntryMod) {
	    int wrLock;

	    wrLock = (0 == NBObtainWriteLock(&tdc->lock, 619));

	    /* Now that we have the write lock, double-check */
	    if (wrLock && (tdc->dflags & DFEntryMod)) {
		tdc->dflags &= ~DFEntryMod;
		MObtainWriteLock(&afs_xdcache, 620);
		afs_WriteDCache(tdc, 1);
		MReleaseWriteLock(&afs_xdcache);
		touchedit = 1;
	    }
	    if (wrLock)
		ReleaseWriteLock(&tdc->lock);
	}

	afs_PutDCache(tdc);
    }

    MObtainWriteLock(&afs_xdcache, 617);
    if (!touchedit && (cacheDiskType != AFS_FCACHE_TYPE_MEM)) {
	/* Touch the file to make sure that the mtime on the file is kept
	 * up-to-date to avoid losing cached files on cold starts because
	 * their mtime seems old...
	 */
	struct afs_fheader theader;

	theader.magic = AFS_FHMAGIC;
	theader.firstCSize = AFS_FIRSTCSIZE;
	theader.otherCSize = AFS_OTHERCSIZE;
	theader.version = AFS_CI_VERSION;
	afs_osi_Write(afs_cacheInodep, 0, &theader, sizeof(theader));
    }
    MReleaseWriteLock(&afs_xdcache);
}

/*
 * afs_MemGetDSlot
 *
 * Description:
 *	Return a pointer to an freshly initialized dcache entry using
 *	a memory-based cache.  The tlock will be read-locked.
 *
 * Parameters:
 *	aslot : Dcache slot to look at.
 *	tmpdc : Ptr to dcache entry.
 *
 * Environment:
 *	Must be called with afs_xdcache write-locked.
 */

struct dcache *
afs_MemGetDSlot(register afs_int32 aslot, register struct dcache *tmpdc)
{
    register struct dcache *tdc;
    int existing = 0;

    AFS_STATCNT(afs_MemGetDSlot);
    if (CheckLock(&afs_xdcache) != -1)
	osi_Panic("getdslot nolock");
    if (aslot < 0 || aslot >= afs_cacheFiles)
	osi_Panic("getdslot slot");
    tdc = afs_indexTable[aslot];
    if (tdc) {
	QRemove(&tdc->lruq);	/* move to queue head */
	QAdd(&afs_DLRU, &tdc->lruq);
	/* We're holding afs_xdcache, but get tlock in case refCount != 0 */
	ObtainWriteLock(&tdc->tlock, 624);
	tdc->refCount++;
	ConvertWToRLock(&tdc->tlock);
	return tdc;
    }
    if (tmpdc == NULL) {
	if (!afs_freeDSList)
	    afs_GetDownDSlot(4);
	if (!afs_freeDSList) {
	    /* none free, making one is better than a panic */
	    afs_stats_cmperf.dcacheXAllocs++;	/* count in case we have a leak */
	    tdc = (struct dcache *)afs_osi_Alloc(sizeof(struct dcache));
#ifdef	KERNEL_HAVE_PIN
	    pin((char *)tdc, sizeof(struct dcache));	/* XXX */
#endif
	} else {
	    tdc = afs_freeDSList;
	    afs_freeDSList = (struct dcache *)tdc->lruq.next;
	    existing = 1;
	}
	tdc->dflags = 0;	/* up-to-date, not in free q */
	tdc->mflags = 0;
	QAdd(&afs_DLRU, &tdc->lruq);
	if (tdc->lruq.prev == &tdc->lruq)
	    osi_Panic("lruq 3");
    } else {
	tdc = tmpdc;
	tdc->f.states = 0;
    }

    /* initialize entry */
    tdc->f.fid.Cell = 0;
    tdc->f.fid.Fid.Volume = 0;
    tdc->f.chunk = -1;
    hones(tdc->f.versionNo);
    tdc->f.inode = aslot;
    tdc->dflags |= DFEntryMod;
    tdc->refCount = 1;
    tdc->index = aslot;
    afs_indexUnique[aslot] = tdc->f.fid.Fid.Unique;

    if (existing) {
	osi_Assert(0 == NBObtainWriteLock(&tdc->lock, 674));
	osi_Assert(0 == NBObtainWriteLock(&tdc->mflock, 675));
	osi_Assert(0 == NBObtainWriteLock(&tdc->tlock, 676));
    }

    RWLOCK_INIT(&tdc->lock, "dcache lock");
    RWLOCK_INIT(&tdc->tlock, "dcache tlock");
    RWLOCK_INIT(&tdc->mflock, "dcache flock");
    ObtainReadLock(&tdc->tlock);

    if (tmpdc == NULL)
	afs_indexTable[aslot] = tdc;
    return tdc;

}				/*afs_MemGetDSlot */

unsigned int last_error = 0, lasterrtime = 0;

/*
 * afs_UFSGetDSlot
 *
 * Description:
 *	Return a pointer to an freshly initialized dcache entry using
 *	a UFS-based disk cache.  The dcache tlock will be read-locked.
 *
 * Parameters:
 *	aslot : Dcache slot to look at.
 *	tmpdc : Ptr to dcache entry.
 *
 * Environment:
 *	afs_xdcache lock write-locked.
 */
struct dcache *
afs_UFSGetDSlot(register afs_int32 aslot, register struct dcache *tmpdc)
{
    register afs_int32 code;
    register struct dcache *tdc;
    int existing = 0;
    int entryok;

    AFS_STATCNT(afs_UFSGetDSlot);
    if (CheckLock(&afs_xdcache) != -1)
	osi_Panic("getdslot nolock");
    if (aslot < 0 || aslot >= afs_cacheFiles)
	osi_Panic("getdslot slot");
    tdc = afs_indexTable[aslot];
    if (tdc) {
	QRemove(&tdc->lruq);	/* move to queue head */
	QAdd(&afs_DLRU, &tdc->lruq);
	/* Grab tlock in case refCount != 0 */
	ObtainWriteLock(&tdc->tlock, 625);
	tdc->refCount++;
	ConvertWToRLock(&tdc->tlock);
	return tdc;
    }
    /* otherwise we should read it in from the cache file */
    /*
     * If we weren't passed an in-memory region to place the file info,
     * we have to allocate one.
     */
    if (tmpdc == NULL) {
	if (!afs_freeDSList)
	    afs_GetDownDSlot(4);
	if (!afs_freeDSList) {
	    /* none free, making one is better than a panic */
	    afs_stats_cmperf.dcacheXAllocs++;	/* count in case we have a leak */
	    tdc = (struct dcache *)afs_osi_Alloc(sizeof(struct dcache));
#ifdef	KERNEL_HAVE_PIN
	    pin((char *)tdc, sizeof(struct dcache));	/* XXX */
#endif
	} else {
	    tdc = afs_freeDSList;
	    afs_freeDSList = (struct dcache *)tdc->lruq.next;
	    existing = 1;
	}
	tdc->dflags = 0;	/* up-to-date, not in free q */
	tdc->mflags = 0;
	QAdd(&afs_DLRU, &tdc->lruq);
	if (tdc->lruq.prev == &tdc->lruq)
	    osi_Panic("lruq 3");
    } else {
	tdc = tmpdc;
	tdc->f.states = 0;
	tdc->ihint = 0;
    }

    /*
     * Seek to the aslot'th entry and read it in.
     */
    code =
	afs_osi_Read(afs_cacheInodep,
		     sizeof(struct fcache) * aslot +
		     sizeof(struct afs_fheader), (char *)(&tdc->f),
		     sizeof(struct fcache));
    entryok = 1;
    if (code != sizeof(struct fcache))
	entryok = 0;
    if (!afs_CellNumValid(tdc->f.fid.Cell))
	entryok = 0;

    if (!entryok) {
	tdc->f.fid.Cell = 0;
	tdc->f.fid.Fid.Volume = 0;
	tdc->f.chunk = -1;
	hones(tdc->f.versionNo);
	tdc->dflags |= DFEntryMod;
#if defined(KERNEL_HAVE_UERROR)
	last_error = getuerror();
#endif
	lasterrtime = osi_Time();
	afs_indexUnique[aslot] = tdc->f.fid.Fid.Unique;
    }
    tdc->refCount = 1;
    tdc->index = aslot;
    if (tdc->f.chunk >= 0)
	tdc->validPos = AFS_CHUNKTOBASE(tdc->f.chunk) + tdc->f.chunkBytes;
    else
	tdc->validPos = 0;

    if (existing) {
	osi_Assert(0 == NBObtainWriteLock(&tdc->lock, 674));
	osi_Assert(0 == NBObtainWriteLock(&tdc->mflock, 675));
	osi_Assert(0 == NBObtainWriteLock(&tdc->tlock, 676));
    }

    RWLOCK_INIT(&tdc->lock, "dcache lock");
    RWLOCK_INIT(&tdc->tlock, "dcache tlock");
    RWLOCK_INIT(&tdc->mflock, "dcache flock");
    ObtainReadLock(&tdc->tlock);

    /*
     * If we didn't read into a temporary dcache region, update the
     * slot pointer table.
     */
    if (tmpdc == NULL)
	afs_indexTable[aslot] = tdc;
    return tdc;

}				/*afs_UFSGetDSlot */



/*
 * afs_WriteDCache
 *
 * Description:
 *	write a particular dcache entry back to its home in the
 *	CacheInfo file.
 *
 * Parameters:
 *	adc   : Pointer to the dcache entry to write.
 *	atime : If true, set the modtime on the file to the current time.
 *
 * Environment:
 *	Must be called with the afs_xdcache lock at least read-locked,
 *	and dcache entry at least read-locked.
 *	The reference count is not changed.
 */

int
afs_WriteDCache(register struct dcache *adc, int atime)
{
    register afs_int32 code;

    if (cacheDiskType == AFS_FCACHE_TYPE_MEM)
	return 0;
    AFS_STATCNT(afs_WriteDCache);
    if (atime)
	adc->f.modTime = osi_Time();
    /*
     * Seek to the right dcache slot and write the in-memory image out to disk.
     */
    afs_cellname_write();
    code =
	afs_osi_Write(afs_cacheInodep,
		      sizeof(struct fcache) * adc->index +
		      sizeof(struct afs_fheader), (char *)(&adc->f),
		      sizeof(struct fcache));
    if (code != sizeof(struct fcache))
	return EIO;
    return 0;
}



/*
 * afs_wakeup
 *
 * Description:
 *	Wake up users of a particular file waiting for stores to take
 *	place.
 *
 * Parameters:
 *	avc : Ptr to related vcache entry.
 *
 * Environment:
 *	Nothing interesting.
 */

int
afs_wakeup(register struct vcache *avc)
{
    register int i;
    register struct brequest *tb;
    tb = afs_brs;
    AFS_STATCNT(afs_wakeup);
    for (i = 0; i < NBRS; i++, tb++) {
	/* if request is valid and for this file, we've found it */
	if (tb->refCount > 0 && avc == tb->vc) {

	    /*
	     * If CSafeStore is on, then we don't awaken the guy
	     * waiting for the store until the whole store has finished.
	     * Otherwise, we do it now.  Note that if CSafeStore is on,
	     * the BStore routine actually wakes up the user, instead
	     * of us.
	     * I think this is redundant now because this sort of thing
	     * is already being handled by the higher-level code.
	     */
	    if ((avc->states & CSafeStore) == 0) {
		tb->code = 0;
		tb->flags |= BUVALID;
		if (tb->flags & BUWAIT) {
		    tb->flags &= ~BUWAIT;
		    afs_osi_Wakeup(tb);
		}
	    }
	    break;
	}
    }
    return 0;
}


/*
 * afs_InitCacheFile
 *
 * Description:
 *	Given a file name and inode, set up that file to be an
 *	active member in the AFS cache.  This also involves checking
 *	the usability of its data.
 *
 * Parameters:
 *	afile  : Name of the cache file to initialize.
 *	ainode : Inode of the file.
 *
 * Environment:
 *	This function is called only during initialization.
 */

int
afs_InitCacheFile(char *afile, ino_t ainode)
{
    register afs_int32 code;
#if defined(AFS_LINUX22_ENV)
    struct dentry *filevp;
#else
    struct vnode *filevp;
#endif
    afs_int32 index;
    int fileIsBad;
    struct osi_file *tfile;
    struct osi_stat tstat;
    register struct dcache *tdc;

    AFS_STATCNT(afs_InitCacheFile);
    index = afs_stats_cmperf.cacheNumEntries;
    if (index >= afs_cacheFiles)
	return EINVAL;

    MObtainWriteLock(&afs_xdcache, 282);
    tdc = afs_GetDSlot(index, NULL);
    ReleaseReadLock(&tdc->tlock);
    MReleaseWriteLock(&afs_xdcache);

    ObtainWriteLock(&tdc->lock, 621);
    MObtainWriteLock(&afs_xdcache, 622);
    if (afile) {
	code = gop_lookupname(afile, AFS_UIOSYS, 0, NULL, &filevp);
	if (code) {
	    ReleaseWriteLock(&afs_xdcache);
	    ReleaseWriteLock(&tdc->lock);
	    afs_PutDCache(tdc);
	    return code;
	}
	/*
	 * We have a VN_HOLD on filevp.  Get the useful info out and
	 * return.  We make use of the fact that the cache is in the
	 * UFS file system, and just record the inode number.
	 */
#ifdef AFS_LINUX22_ENV
	tdc->f.inode = VTOI(filevp->d_inode)->i_number;
	dput(filevp);
#else
	tdc->f.inode = afs_vnodeToInumber(filevp);
#ifdef AFS_DEC_ENV
	grele(filevp);
#else
	AFS_RELE(filevp);
#endif
#endif /* AFS_LINUX22_ENV */
    } else {
	tdc->f.inode = ainode;
    }
    fileIsBad = 0;
    if ((tdc->f.states & DWriting) || tdc->f.fid.Fid.Volume == 0)
	fileIsBad = 1;
    tfile = osi_UFSOpen(tdc->f.inode);
    code = afs_osi_Stat(tfile, &tstat);
    if (code)
	osi_Panic("initcachefile stat");

    /*
     * If file size doesn't match the cache info file, it's probably bad.
     */
    if (tdc->f.chunkBytes != tstat.size)
	fileIsBad = 1;
    tdc->f.chunkBytes = 0;

    /*
     * If file changed within T (120?) seconds of cache info file, it's
     * probably bad.  In addition, if slot changed within last T seconds,
     * the cache info file may be incorrectly identified, and so slot
     * may be bad.
     */
    if (cacheInfoModTime < tstat.mtime + 120)
	fileIsBad = 1;
    if (cacheInfoModTime < tdc->f.modTime + 120)
	fileIsBad = 1;
    /* In case write through is behind, make sure cache items entry is
     * at least as new as the chunk.
     */
    if (tdc->f.modTime < tstat.mtime)
	fileIsBad = 1;
    if (fileIsBad) {
	tdc->f.fid.Fid.Volume = 0;	/* not in the hash table */
	if (tstat.size != 0)
	    osi_UFSTruncate(tfile, 0);
	/* put entry in free cache slot list */
	afs_dvnextTbl[tdc->index] = afs_freeDCList;
	afs_freeDCList = index;
	afs_freeDCCount++;
	afs_indexFlags[index] |= IFFree;
	afs_indexUnique[index] = 0;
    } else {
	/*
	 * We must put this entry in the appropriate hash tables.
	 * Note that i is still set from the above DCHash call
	 */
	code = DCHash(&tdc->f.fid, tdc->f.chunk);
	afs_dcnextTbl[tdc->index] = afs_dchashTbl[code];
	afs_dchashTbl[code] = tdc->index;
	code = DVHash(&tdc->f.fid);
	afs_dvnextTbl[tdc->index] = afs_dvhashTbl[code];
	afs_dvhashTbl[code] = tdc->index;
	afs_AdjustSize(tdc, tstat.size);	/* adjust to new size */
	if (tstat.size > 0)
	    /* has nontrivial amt of data */
	    afs_indexFlags[index] |= IFEverUsed;
	afs_stats_cmperf.cacheFilesReused++;
	/*
	 * Initialize index times to file's mod times; init indexCounter
	 * to max thereof
	 */
	hset32(afs_indexTimes[index], tstat.atime);
	if (hgetlo(afs_indexCounter) < tstat.atime) {
	    hset32(afs_indexCounter, tstat.atime);
	}
	afs_indexUnique[index] = tdc->f.fid.Fid.Unique;
    }				/*File is not bad */

    osi_UFSClose(tfile);
    tdc->f.states &= ~DWriting;
    tdc->dflags &= ~DFEntryMod;
    /* don't set f.modTime; we're just cleaning up */
    afs_WriteDCache(tdc, 0);
    ReleaseWriteLock(&afs_xdcache);
    ReleaseWriteLock(&tdc->lock);
    afs_PutDCache(tdc);
    afs_stats_cmperf.cacheNumEntries++;
    return 0;
}


/*Max # of struct dcache's resident at any time*/
/*
 * If 'dchint' is enabled then in-memory dcache min is increased because of
 * crashes...
 */
#define DDSIZE 200

/* 
 * afs_dcacheInit
 *
 * Description:
 *	Initialize dcache related variables.
 */
void
afs_dcacheInit(int afiles, int ablocks, int aDentries, int achunk, int aflags)
{
    register struct dcache *tdp;
    int i;
    int code;

    afs_freeDCList = NULLIDX;
    afs_discardDCList = NULLIDX;
    afs_freeDCCount = 0;
    afs_freeDSList = NULL;
    hzero(afs_indexCounter);

    LOCK_INIT(&afs_xdcache, "afs_xdcache");

    /*
     * Set chunk size
     */
    if (achunk) {
	if (achunk < 0 || achunk > 30)
	    achunk = 13;	/* Use default */
	AFS_SETCHUNKSIZE(achunk);
    }

    if (!aDentries)
	aDentries = DDSIZE;

    if (aflags & AFSCALL_INIT_MEMCACHE) {
	/*
	 * Use a memory cache instead of a disk cache
	 */
	cacheDiskType = AFS_FCACHE_TYPE_MEM;
	afs_cacheType = &afs_MemCacheOps;
	afiles = (afiles < aDentries) ? afiles : aDentries;	/* min */
	ablocks = afiles * (AFS_FIRSTCSIZE / 1024);
	/* ablocks is reported in 1K blocks */
	code = afs_InitMemCache(afiles, AFS_FIRSTCSIZE, aflags);
	if (code != 0) {
	    printf("afsd: memory cache too large for available memory.\n");
	    printf("afsd: AFS files cannot be accessed.\n\n");
	    dcacheDisabled = 1;
	    afiles = ablocks = 0;
	} else
	    printf("Memory cache: Allocating %d dcache entries...",
		   aDentries);
    } else {
	cacheDiskType = AFS_FCACHE_TYPE_UFS;
	afs_cacheType = &afs_UfsCacheOps;
    }

    if (aDentries > 512)
	afs_dhashsize = 2048;
    /* initialize hash tables */
    afs_dvhashTbl =
	(afs_int32 *) afs_osi_Alloc(afs_dhashsize * sizeof(afs_int32));
    afs_dchashTbl =
	(afs_int32 *) afs_osi_Alloc(afs_dhashsize * sizeof(afs_int32));
    for (i = 0; i < afs_dhashsize; i++) {
	afs_dvhashTbl[i] = NULLIDX;
	afs_dchashTbl[i] = NULLIDX;
    }
    afs_dvnextTbl = (afs_int32 *) afs_osi_Alloc(afiles * sizeof(afs_int32));
    afs_dcnextTbl = (afs_int32 *) afs_osi_Alloc(afiles * sizeof(afs_int32));
    for (i = 0; i < afiles; i++) {
	afs_dvnextTbl[i] = NULLIDX;
	afs_dcnextTbl[i] = NULLIDX;
    }

    /* Allocate and zero the pointer array to the dcache entries */
    afs_indexTable = (struct dcache **)
	afs_osi_Alloc(sizeof(struct dcache *) * afiles);
    memset((char *)afs_indexTable, 0, sizeof(struct dcache *) * afiles);
    afs_indexTimes =
	(afs_hyper_t *) afs_osi_Alloc(afiles * sizeof(afs_hyper_t));
    memset((char *)afs_indexTimes, 0, afiles * sizeof(afs_hyper_t));
    afs_indexUnique =
	(afs_int32 *) afs_osi_Alloc(afiles * sizeof(afs_uint32));
    memset((char *)afs_indexUnique, 0, afiles * sizeof(afs_uint32));
    afs_indexFlags = (u_char *) afs_osi_Alloc(afiles * sizeof(u_char));
    memset((char *)afs_indexFlags, 0, afiles * sizeof(char));

    /* Allocate and thread the struct dcache entries themselves */
    tdp = afs_Initial_freeDSList =
	(struct dcache *)afs_osi_Alloc(aDentries * sizeof(struct dcache));
    memset((char *)tdp, 0, aDentries * sizeof(struct dcache));
#ifdef	KERNEL_HAVE_PIN
    pin((char *)afs_indexTable, sizeof(struct dcache *) * afiles);	/* XXX */
    pin((char *)afs_indexTimes, sizeof(afs_hyper_t) * afiles);	/* XXX */
    pin((char *)afs_indexFlags, sizeof(char) * afiles);	/* XXX */
    pin((char *)afs_indexUnique, sizeof(afs_int32) * afiles);	/* XXX */
    pin((char *)tdp, aDentries * sizeof(struct dcache));	/* XXX */
    pin((char *)afs_dvhashTbl, sizeof(afs_int32) * afs_dhashsize);	/* XXX */
    pin((char *)afs_dchashTbl, sizeof(afs_int32) * afs_dhashsize);	/* XXX */
    pin((char *)afs_dcnextTbl, sizeof(afs_int32) * afiles);	/* XXX */
    pin((char *)afs_dvnextTbl, sizeof(afs_int32) * afiles);	/* XXX */
#endif

    afs_freeDSList = &tdp[0];
    for (i = 0; i < aDentries - 1; i++) {
	tdp[i].lruq.next = (struct afs_q *)(&tdp[i + 1]);
    }
    tdp[aDentries - 1].lruq.next = (struct afs_q *)0;

    afs_stats_cmperf.cacheBlocksOrig = afs_stats_cmperf.cacheBlocksTotal =
	afs_cacheBlocks = ablocks;
    afs_ComputeCacheParms();	/* compute parms based on cache size */

    afs_dcentries = aDentries;
    afs_blocksUsed = 0;
    QInit(&afs_DLRU);
}

/*
 * shutdown_dcache
 *
 */
void
shutdown_dcache(void)
{
    int i;

    afs_osi_Free(afs_dvnextTbl, afs_cacheFiles * sizeof(afs_int32));
    afs_osi_Free(afs_dcnextTbl, afs_cacheFiles * sizeof(afs_int32));
    afs_osi_Free(afs_indexTable, afs_cacheFiles * sizeof(struct dcache *));
    afs_osi_Free(afs_indexTimes, afs_cacheFiles * sizeof(afs_hyper_t));
    afs_osi_Free(afs_indexUnique, afs_cacheFiles * sizeof(afs_uint32));
    afs_osi_Free(afs_indexFlags, afs_cacheFiles * sizeof(u_char));
    afs_osi_Free(afs_Initial_freeDSList,
		 afs_dcentries * sizeof(struct dcache));
#ifdef	KERNEL_HAVE_PIN
    unpin((char *)afs_dcnextTbl, afs_cacheFiles * sizeof(afs_int32));
    unpin((char *)afs_dvnextTbl, afs_cacheFiles * sizeof(afs_int32));
    unpin((char *)afs_indexTable, afs_cacheFiles * sizeof(struct dcache *));
    unpin((char *)afs_indexTimes, afs_cacheFiles * sizeof(afs_hyper_t));
    unpin((char *)afs_indexUnique, afs_cacheFiles * sizeof(afs_uint32));
    unpin((u_char *) afs_indexFlags, afs_cacheFiles * sizeof(u_char));
    unpin(afs_Initial_freeDSList, afs_dcentries * sizeof(struct dcache));
#endif


    for (i = 0; i < afs_dhashsize; i++) {
	afs_dvhashTbl[i] = NULLIDX;
	afs_dchashTbl[i] = NULLIDX;
    }

    afs_osi_Free(afs_dvhashTbl, afs_dhashsize * sizeof(afs_int32));
    afs_osi_Free(afs_dchashTbl, afs_dhashsize * sizeof(afs_int32));

    afs_blocksUsed = afs_dcentries = 0;
    hzero(afs_indexCounter);

    afs_freeDCCount = 0;
    afs_freeDCList = NULLIDX;
    afs_discardDCList = NULLIDX;
    afs_freeDSList = afs_Initial_freeDSList = 0;

    LOCK_INIT(&afs_xdcache, "afs_xdcache");
    QInit(&afs_DLRU);

}
