openbsd-20021112

[openafs.git] / src / afs / VNOPS / afs_vnop_lookup.c

/*
 * 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:
 * afs_lookup
 * EvalMountPoint
 * afs_DoBulkStat
 *
 * Locals:
 * afs_strcat
 * AFS_EQ_ATSYS (macro)
 * afs_index
 */

#include <afsconfig.h>
#include "afs/param.h"

RCSID("$Header$");

#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/nfsclient.h"
#include "afs/exporter.h"
#include "afs/afs_osidnlc.h"


extern struct DirEntry * afs_dir_GetBlob();

#ifdef AFS_LINUX22_ENV
extern struct inode_operations afs_symlink_iops, afs_dir_iops;
#endif


afs_int32 afs_bulkStatsDone;
static int bulkStatCounter = 0; /* counter for bulk stat seq. numbers */
int afs_fakestat_enable = 0;    /* 1: fakestat-all, 2: fakestat-crosscell */


/* this would be faster if it did comparison as int32word, but would be 
 * dependant on byte-order and alignment, and I haven't figured out
 * what "@sys" is in binary... */
#define AFS_EQ_ATSYS(name) (((name)[0]=='@')&&((name)[1]=='s')&&((name)[2]=='y')&&((name)[3]=='s')&&(!(name)[4]))

/* call under write lock, evaluate mvid field from a mt pt.
 * avc is the vnode of the mount point object; must be write-locked.
 * advc is the vnode of the containing directory (optional; if NULL and
 *   EvalMountPoint succeeds, caller must initialize *avolpp->dotdot)
 * avolpp is where we return a pointer to the volume named by the mount pt, if success
 * areq is the identity of the caller.
 *
 * NOTE: this function returns a held volume structure in *volpp if it returns 0!
 */
int EvalMountPoint(register struct vcache *avc, struct vcache *advc, 
        struct volume **avolpp, register struct vrequest *areq)
{
    afs_int32  code;
    struct volume *tvp = 0;
    struct VenusFid tfid;
    struct cell *tcell;
    char   *cpos, *volnamep;
    char   type, *buf;
    afs_int32  prefetchRO;          /* 1=>No  2=>Yes */
    afs_int32  mtptCell, assocCell, hac=0;
    afs_int32  samecell, roname, len;

    AFS_STATCNT(EvalMountPoint);
#ifdef notdef
    if (avc->mvid && (avc->states & CMValid)) return 0; /* done while racing */
#endif
    *avolpp = NULL;
    code = afs_HandleLink(avc, areq);
    if (code) return code;

    /* Determine which cell and volume the mointpoint goes to */
    type = avc->linkData[0];                   /* '#'=>Regular '%'=>RW */
    cpos = afs_strchr(&avc->linkData[1], ':');  /* if cell name present */
    if (cpos) {
       volnamep = cpos+1;
       *cpos = 0;
       tcell = afs_GetCellByName(&avc->linkData[1], READ_LOCK);
       *cpos =  ':';
    } else {
       volnamep = &avc->linkData[1];
       tcell = afs_GetCell(avc->fid.Cell, READ_LOCK);
    }
    if (!tcell) return ENODEV;

    mtptCell = tcell->cellNum;              /* The cell for the mountpoint */
    if (tcell->lcellp) {
       hac = 1;                             /* has associated cell */
       assocCell = tcell->lcellp->cellNum;  /* The associated cell */
    }
    afs_PutCell(tcell, READ_LOCK);          

    /* Is volume name a "<n>.backup" or "<n>.readonly" name */
    len = strlen(volnamep);
    roname = ((len > 9) && (strcmp(&volnamep[len - 9],".readonly") == 0)) ||
             ((len > 7) && (strcmp(&volnamep[len - 7],".backup")   == 0));

    /* When we cross mountpoint, do we stay in the same cell */
    samecell = (avc->fid.Cell == mtptCell) || (hac && (avc->fid.Cell == assocCell));

    /* Decide whether to prefetch the RO. Also means we want the RO.
     * If this is a regular mountpoint with a RW volume name and
     * we cross a cell boundary -or- start from a RO volume, then we will
     * want to prefetch the RO volume when we get the RW below.
     */
    if ( (type == '#') && !roname && (!samecell || (avc->states & CRO)) ) {
       prefetchRO = 2; /* Yes, prefetch the RO */
    } else {
       prefetchRO = 1; /* No prefetch of the RO */
    }

    /* Get the volume struct. Unless this volume name has ".readonly" or
     * ".backup" in it, this will get the volume struct for the RW volume.
     * The RO volume will be prefetched if requested (but not returned).
     */
    tvp = afs_GetVolumeByName(volnamep, mtptCell, prefetchRO, areq, WRITE_LOCK);

    /* If no volume was found in this cell, try the associated linked cell */
    if (!tvp && hac && areq->volumeError) {
       tvp = afs_GetVolumeByName(volnamep, assocCell, prefetchRO, areq, WRITE_LOCK);
    }

    /* Still not found. If we are looking for the RO, then perhaps the RW 
     * doesn't exist? Try adding ".readonly" to volname and look for that.
     * Don't know why we do this. Would have still found it in above call - jpm.
     */
    if (!tvp && (prefetchRO == 2)) {
        buf = (char *)osi_AllocSmallSpace(strlen(volnamep)+10);

        strcpy(buf, volnamep);
        afs_strcat(buf, ".readonly");

        tvp = afs_GetVolumeByName(buf, mtptCell, 1, areq, WRITE_LOCK);
       
        /* Try the associated linked cell if failed */
        if (!tvp && hac && areq->volumeError) {
            tvp = afs_GetVolumeByName(buf, assocCell, 1, areq, WRITE_LOCK);
        }
        osi_FreeSmallSpace(buf);
    }
  
    if (!tvp) return ENODEV;       /* Couldn't find the volume */

    /* Don't cross mountpoint from a BK to a BK volume */
    if ((avc->states & CBackup) && (tvp->states & VBackup)) {
        afs_PutVolume(tvp, WRITE_LOCK);
        return ENODEV;
    }

    /* If we want (prefetched) the RO and it exists, then drop the
     * RW volume and get the RO. Othewise, go with the RW.
     */
    if ((prefetchRO == 2) && tvp->roVol) {
       tfid.Fid.Volume = tvp->roVol;                 /* remember RO volume */
       tfid.Cell       = tvp->cell;
       afs_PutVolume(tvp, WRITE_LOCK);               /* release old volume */
       tvp = afs_GetVolume(&tfid, areq, WRITE_LOCK); /* get the new one */
       if (!tvp) return ENODEV;                      /* oops, can't do it */
    }

    if (avc->mvid == 0)
        avc->mvid = (struct VenusFid *) osi_AllocSmallSpace(sizeof(struct VenusFid));
    avc->mvid->Cell = tvp->cell;
    avc->mvid->Fid.Volume = tvp->volume;
    avc->mvid->Fid.Vnode = 1;
    avc->mvid->Fid.Unique = 1;
    avc->states |= CMValid;

    /* Used to: if the mount point is stored within a backup volume,
     * then we should only update the parent pointer information if
     * there's none already set, so as to avoid updating a volume's ..
     * info with something in an OldFiles directory.
     *
     * Next two lines used to be under this if:
     *
     * if (!(avc->states & CBackup) || tvp->dotdot.Fid.Volume == 0)
     *
     * Now: update mount point back pointer on every call, so that we handle
     * multiple mount points better.  This way, when du tries to go back
     * via chddir(".."), it will end up exactly where it started, yet
     * cd'ing via a new path to a volume will reset the ".." pointer
     * to the new path.
     */
    tvp->mtpoint = avc->fid;    /* setup back pointer to mtpoint */
    if (advc) tvp->dotdot  = advc->fid;

    *avolpp = tvp;
    return 0;
}

/*
 * afs_InitFakeStat
 *
 * Must be called on an afs_fakestat_state object before calling
 * afs_EvalFakeStat or afs_PutFakeStat.  Calling afs_PutFakeStat
 * without calling afs_EvalFakeStat is legal, as long as this
 * function is called.
 */
void afs_InitFakeStat(struct afs_fakestat_state *state)
{
    if (!afs_fakestat_enable)
        return;

    state->valid = 1;
    state->did_eval = 0;
    state->need_release = 0;
}

/*
 * afs_EvalFakeStat_int
 *
 * The actual implementation of afs_EvalFakeStat and afs_TryEvalFakeStat,
 * which is called by those wrapper functions.
 *
 * Only issues RPCs if canblock is non-zero.
 */
int afs_EvalFakeStat_int(struct vcache **avcp, struct afs_fakestat_state *state,
        struct vrequest *areq, int canblock)
{
    struct vcache *tvc, *root_vp;
    struct volume *tvolp = NULL;
    int code = 0;

    if (!afs_fakestat_enable)
        return 0;

    osi_Assert(state->valid == 1);
    osi_Assert(state->did_eval == 0);
    state->did_eval = 1;

    tvc = *avcp;
    if (tvc->mvstat != 1)
        return 0;

    /* Is the call to VerifyVCache really necessary? */
    code = afs_VerifyVCache(tvc, areq);
    if (code)
        goto done;
    if (canblock) {
        ObtainWriteLock(&tvc->lock, 599);
        code = EvalMountPoint(tvc, NULL, &tvolp, areq);
        ReleaseWriteLock(&tvc->lock);
        if (code)
            goto done;
        if (tvolp) {
            tvolp->dotdot = tvc->fid;
            tvolp->dotdot.Fid.Vnode = tvc->parentVnode;
            tvolp->dotdot.Fid.Unique = tvc->parentUnique;
        }
    }
    if (tvc->mvid && (tvc->states & CMValid)) {
        if (!canblock) {
            afs_int32 retry;

            do {
                retry = 0;
                ObtainWriteLock(&afs_xvcache, 597);
                root_vp = afs_FindVCache(tvc->mvid, &retry, 0);
                if (root_vp && retry) {
                    ReleaseWriteLock(&afs_xvcache);
                    afs_PutVCache(root_vp);
                }
            } while (root_vp && retry);
            ReleaseWriteLock(&afs_xvcache);
        } else {
            root_vp = afs_GetVCache(tvc->mvid, areq, NULL, NULL);
        }
        if (!root_vp) {
            code = canblock ? ENOENT : 0;
            goto done;
        }
        if (tvolp) {
            /* Is this always kosher?  Perhaps we should instead use
             * NBObtainWriteLock to avoid potential deadlock.
             */
            ObtainWriteLock(&root_vp->lock, 598);
            if (!root_vp->mvid)
                root_vp->mvid = osi_AllocSmallSpace(sizeof(struct VenusFid));
            *root_vp->mvid = tvolp->dotdot;
            ReleaseWriteLock(&root_vp->lock);
        }
        state->need_release = 1;
        state->root_vp = root_vp;
        *avcp = root_vp;
        code = 0;
    } else {
        code = canblock ? ENOENT : 0;
    }

done:
    if (tvolp)
        afs_PutVolume(tvolp, WRITE_LOCK);
    return code;
}

/*
 * afs_EvalFakeStat
 *
 * Automatically does the equivalent of EvalMountPoint for vcache entries
 * which are mount points.  Remembers enough state to properly release
 * the volume root vcache when afs_PutFakeStat() is called.
 *
 * State variable must be initialized by afs_InitFakeState() beforehand.
 *
 * Returns 0 when everything succeeds and *avcp points to the vcache entry
 * that should be used for the real vnode operation.  Returns non-zero if
 * something goes wrong and the error code should be returned to the user.
 */
int
afs_EvalFakeStat(struct vcache **avcp, struct afs_fakestat_state *state,
        struct vrequest *areq)
{
    return afs_EvalFakeStat_int(avcp, state, areq, 1);
}

/*
 * afs_TryEvalFakeStat
 *
 * Same as afs_EvalFakeStat, but tries not to talk to remote servers
 * and only evaluate the mount point if all the data is already in
 * local caches.
 *
 * Returns 0 if everything succeeds and *avcp points to a valid
 * vcache entry (possibly evaluated).
 */
int afs_TryEvalFakeStat(struct vcache **avcp, struct afs_fakestat_state *state, 
        struct vrequest *areq)
{
    return afs_EvalFakeStat_int(avcp, state, areq, 0);
}

/*
 * afs_PutFakeStat
 *
 * Perform any necessary cleanup at the end of a vnode op, given that
 * afs_InitFakeStat was previously called with this state.
 */
void afs_PutFakeStat(struct afs_fakestat_state *state)
{
    if (!afs_fakestat_enable)
        return;

    osi_Assert(state->valid == 1);
    if (state->need_release)
        afs_PutVCache(state->root_vp);
    state->valid = 0;
}
    
int afs_ENameOK(register char *aname)
{
    register int tlen;

    AFS_STATCNT(ENameOK);
    tlen = strlen(aname);
    if (tlen >= 4 && strcmp(aname+tlen-4, "@sys") == 0) return 0;
    return 1;
}

int afs_getsysname(register struct vrequest *areq, register struct vcache *adp, 
        register char *bufp)
{
    register struct unixuser *au;
    register afs_int32 error;

    if (!afs_nfsexporter) {
        strcpy(bufp, afs_sysname);
        return 0;
    }
    AFS_STATCNT(getsysname);
    au = afs_GetUser(areq->uid, adp->fid.Cell, 0);
    afs_PutUser(au, 0); 
    if (au->exporter) {
        error = EXP_SYSNAME(au->exporter, NULL, bufp);
        if (error) 
            strcpy(bufp, "@sys");
        return -1;
    } else {
        strcpy(bufp, afs_sysname);
        return 0;
    }
}

void Check_AtSys(register struct vcache *avc, const char *aname, 
        struct sysname_info *state, struct vrequest *areq)
{
    if (AFS_EQ_ATSYS(aname)) {
        state->offset = 0;
        state->name = (char *) osi_AllocLargeSpace(AFS_SMALLOCSIZ);
        state->allocked = 1;
        state->index = afs_getsysname(areq, avc, state->name);
    } else {
        state->offset = -1;
        state->allocked = 0;
        state->index = 0;
        state->name = aname;
    }
}

int Next_AtSys(register struct vcache *avc, struct vrequest *areq, 
        struct sysname_info *state)
{
  if (state->index == -1)
    return 0;   /* No list */

  /* Check for the initial state of aname != "@sys" in Check_AtSys*/
  if (state->offset == -1 && state->allocked == 0) {
    register char *tname;
    /* Check for .*@sys */
      for (tname=state->name; *tname; tname++)
        /*Move to the end of the string*/;
      if ((tname > state->name + 4) && (AFS_EQ_ATSYS(tname-4))) {
        state->offset = (tname - 4) - state->name;
        tname = (char *) osi_AllocLargeSpace(AFS_LRALLOCSIZ);
        strncpy(tname, state->name, state->offset);
        state->name = tname;
        state->allocked = 1;
        state->index = afs_getsysname(areq, avc, state->name+state->offset);
        return 1;
      } else
        return 0; /* .*@sys doesn't match either */
  } else if (++(state->index) >= afs_sysnamecount
             || !afs_sysnamelist[(int)state->index])
    return 0;   /* end of list */
  strcpy(state->name+state->offset, afs_sysnamelist[(int)state->index]);
  return 1;
}

#if (defined(AFS_SGI62_ENV) || defined(AFS_SUN57_64BIT_ENV))
extern int BlobScan(ino64_t *afile, afs_int32 ablob);
#else
#if defined AFS_LINUX_64BIT_KERNEL
extern int BlobScan(long *afile, afs_int32 ablob);
#else
extern int BlobScan(afs_int32 *afile, afs_int32 ablob);
#endif
#endif


/* called with an unlocked directory and directory cookie.  Areqp
 * describes who is making the call.
 * Scans the next N (about 30, typically) directory entries, and does
 * a bulk stat call to stat them all.
 *
 * Must be very careful when merging in RPC responses, since we dont
 * want to overwrite newer info that was added by a file system mutating
 * call that ran concurrently with our bulk stat call.
 *
 * We do that, as described below, by not merging in our info (always
 * safe to skip the merge) if the status info is valid in the vcache entry.
 *
 * If adapt ever implements the bulk stat RPC, then this code will need to
 * ensure that vcaches created for failed RPC's to older servers have the
 * CForeign bit set.
 */
static struct vcache *BStvc = NULL;

int afs_DoBulkStat(struct vcache *adp, long dirCookie, struct vrequest *areqp)
{
    int nentries;               /* # of entries to prefetch */
    int nskip;                  /* # of slots in the LRU queue to skip */
    struct vcache *lruvcp;      /* vcache ptr of our goal pos in LRU queue */
    struct dcache *dcp;         /* chunk containing the dir block */
    char *statMemp;             /* status memory block */
    char *cbfMemp;              /* callback and fid memory block */
    afs_size_t temp;            /* temp for holding chunk length, &c. */
    struct AFSFid *fidsp;       /* file IDs were collecting */
    struct AFSCallBack *cbsp;   /* call back pointers */
    struct AFSCallBack *tcbp;   /* temp callback ptr */
    struct AFSFetchStatus *statsp;      /* file status info */
    struct AFSVolSync volSync;  /* vol sync return info */
    struct vcache *tvcp;        /* temp vcp */
    struct afs_q *tq;           /* temp queue variable */
    AFSCBFids fidParm;          /* file ID parm for bulk stat */
    AFSBulkStats statParm;      /* stat info parm for bulk stat */
    int fidIndex;               /* which file were stating */
    struct conn *tcp;           /* conn for call */
    AFSCBs cbParm;              /* callback parm for bulk stat */
    struct server *hostp = 0;   /* host we got callback from */
    long startTime;             /* time we started the call,
                                 * for callback expiration base
                                 */
    afs_size_t statSeqNo;       /* Valued of file size to detect races */
    int code;                   /* error code */
    long newIndex;              /* new index in the dir */
    struct DirEntry *dirEntryp; /* dir entry we are examining */
    int i;
    struct VenusFid afid;       /* file ID we are using now */
    struct VenusFid tfid;       /* another temp. file ID */
    afs_int32 retry;                  /* handle low-level SGI MP race conditions */
    long volStates;             /* flags from vol structure */
    struct volume *volp=0;      /* volume ptr */
    struct VenusFid dotdot;
    int flagIndex;              /* First file with bulk fetch flag set */
    int inlinebulk=0;           /* Did we use InlineBulk RPC or not? */
    XSTATS_DECLS

    /* first compute some basic parameters.  We dont want to prefetch more
     * than a fraction of the cache in any given call, and we want to preserve
     * a portion of the LRU queue in any event, so as to avoid thrashing
     * the entire stat cache (we will at least leave some of it alone).
     * presently dont stat more than 1/8 the cache in any one call.      */
    nentries = afs_cacheStats / 8;

    /* dont bother prefetching more than one calls worth of info */
    if (nentries > AFSCBMAX) nentries = AFSCBMAX;

    /* heuristic to make sure that things fit in 4K.  This means that
     * we shouldnt make it any bigger than 47 entries.  I am typically
     * going to keep it a little lower, since we don't want to load
     * too much of the stat cache.
     */
    if (nentries > 30) nentries = 30;

    /* now, to reduce the stack size, well allocate two 4K blocks,
     * one for fids and callbacks, and one for stat info.  Well set
     * up our pointers to the memory from there, too.
     */
    statMemp = osi_AllocLargeSpace(nentries * sizeof(AFSFetchStatus));
    statsp = (struct AFSFetchStatus *) statMemp;
    cbfMemp = osi_AllocLargeSpace(nentries *
        (sizeof(AFSCallBack) + sizeof(AFSFid)));
    fidsp = (AFSFid *) cbfMemp;
    cbsp = (AFSCallBack *) (cbfMemp + nentries * sizeof(AFSFid));

    /* next, we must iterate over the directory, starting from the specified
     * cookie offset (dirCookie), and counting out nentries file entries.
     * We skip files that already have stat cache entries, since we
     * dont want to bulk stat files that are already in the cache.
     */
tagain:
    code = afs_VerifyVCache(adp, areqp);
    if (code) goto done;

    dcp = afs_GetDCache(adp, (afs_size_t) 0, areqp, &temp, &temp, 1);
    if (!dcp) {
        code = ENOENT;
        goto done;
    }

    /* lock the directory cache entry */
    ObtainReadLock(&adp->lock);
    ObtainReadLock(&dcp->lock);

    /*
     * Make sure that the data in the cache is current. There are two
     * cases we need to worry about:
     * 1. The cache data is being fetched by another process.
     * 2. The cache data is no longer valid
     */
    while ((adp->states & CStatd)
           && (dcp->dflags & DFFetching)
           && hsame(adp->m.DataVersion, dcp->f.versionNo)) {
        afs_Trace4(afs_iclSetp, CM_TRACE_DCACHEWAIT,
                        ICL_TYPE_STRING, __FILE__,
                        ICL_TYPE_INT32, __LINE__,
                        ICL_TYPE_POINTER, dcp,
                        ICL_TYPE_INT32, dcp->dflags);
        ReleaseReadLock(&dcp->lock);
        ReleaseReadLock(&adp->lock);
        afs_osi_Sleep(&dcp->validPos);
        ObtainReadLock(&adp->lock);
        ObtainReadLock(&dcp->lock);
    }
    if (!(adp->states & CStatd)
        || !hsame(adp->m.DataVersion, dcp->f.versionNo)) {
        ReleaseReadLock(&dcp->lock);
        ReleaseReadLock(&adp->lock);
        afs_PutDCache(dcp);
        goto tagain;
    }

    /* Generate a sequence number so we can tell whether we should
     * store the attributes when processing the response. This number is
     * stored in the file size when we set the CBulkFetching bit. If the
     * CBulkFetching is still set and this value hasn't changed, then
     * we know we were the last to set CBulkFetching bit for this file,
     * and it is safe to set the status information for this file.
     */
    statSeqNo = bulkStatCounter++;

    /* now we have dir data in the cache, so scan the dir page */
    fidIndex = 0;
    flagIndex = 0;
    while (1) { /* Should probably have some constant bound */
        /* look for first safe entry to examine in the directory.  BlobScan
         * looks for a the 1st allocated dir after the dirCookie slot.
         */
        newIndex = BlobScan(&dcp->f.inode, (dirCookie>>5));
        if (newIndex == 0) break;

        /* remember the updated directory cookie */
        dirCookie = newIndex << 5;

        /* get a ptr to the dir entry */
        dirEntryp =(struct DirEntry *)afs_dir_GetBlob(&dcp->f.inode, newIndex);
        if (!dirEntryp) break;

        /* dont copy more than we have room for */
        if (fidIndex >= nentries) {
          DRelease((struct buffer *) dirEntryp, 0);
          break;
        }

        /* now, if the dir entry looks good, copy it out to our list.  Vnode
         * 0 means deleted, although it should also be free were it deleted.
         */
        if (dirEntryp->fid.vnode != 0) {
            /* dont copy entries we have in our cache.  This check will
             * also make us skip "." and probably "..", unless it has
             * disappeared from the cache since we did our namei call.
             */
            tfid.Cell = adp->fid.Cell;
            tfid.Fid.Volume = adp->fid.Fid.Volume;
            tfid.Fid.Vnode = ntohl(dirEntryp->fid.vnode);
            tfid.Fid.Unique = ntohl(dirEntryp->fid.vunique);
            do {
              retry = 0;
              ObtainWriteLock(&afs_xvcache, 130);
              tvcp = afs_FindVCache(&tfid, &retry, 0 /* no stats | LRU */);
              if (tvcp && retry) {
                ReleaseWriteLock(&afs_xvcache);
                afs_PutVCache(tvcp);
              }
            } while (tvcp && retry);
            if (!tvcp) {          /* otherwise, create manually */
              tvcp = afs_NewVCache(&tfid, hostp);
              ObtainWriteLock(&tvcp->lock, 505);
              ReleaseWriteLock(&afs_xvcache);
              afs_RemoveVCB(&tfid);
              ReleaseWriteLock(&tvcp->lock);
            } else {
              ReleaseWriteLock(&afs_xvcache);
            }
            if (!tvcp)
              goto done; /* can't happen at present, more's the pity */

            /* WARNING: afs_DoBulkStat uses the Length field to store a
             * sequence number for each bulk status request. Under no
             * circumstances should afs_DoBulkStat store a sequence number
             * if the new length will be ignored when afs_ProcessFS is
             * called with new stats. */
#ifdef AFS_SGI_ENV
            if (!(tvcp->states & (CStatd|CBulkFetching))
                && (tvcp->execsOrWriters <= 0)
                && !afs_DirtyPages(tvcp)
                && !AFS_VN_MAPPED((vnode_t*)tvcp))
#else
            if (!(tvcp->states & (CStatd|CBulkFetching))
                && (tvcp->execsOrWriters <= 0) 
                && !afs_DirtyPages(tvcp))
#endif

            {
                /* this entry doesnt exist in the cache, and is not
                 * already being fetched by someone else, so add it to the
                 * list of file IDs to obtain.
                 *
                 * We detect a callback breaking race condition by checking the
                 * CBulkFetching state bit and the value in the file size.
                 * It is safe to set the status only if the CBulkFetching
                 * flag is still set and the value in the file size does
                 * not change.
                 *
                 * Don't fetch status for dirty files. We need to
                 * preserve the value of the file size. We could
                 * flush the pages, but it wouldn't be worthwhile.
                 */
                memcpy((char *)(fidsp+fidIndex), (char *) &tfid.Fid, sizeof(*fidsp));
                tvcp->states |= CBulkFetching;
                tvcp->m.Length = statSeqNo;
                fidIndex++;
            }
            afs_PutVCache(tvcp);
        }       /* if dir vnode has non-zero entry */

        /* move to the next dir entry by adding in the # of entries
         * used by this dir entry.
         */
        temp = afs_dir_NameBlobs(dirEntryp->name) << 5;
        DRelease((struct buffer *) dirEntryp, 0);
        if (temp <= 0) break;
        dirCookie += temp;
    }   /* while loop over all dir entries */

    /* now release the dir lock and prepare to make the bulk RPC */
    ReleaseReadLock(&dcp->lock);
    ReleaseReadLock(&adp->lock);

    /* release the chunk */
    afs_PutDCache(dcp);

    /* dont make a null call */
    if (fidIndex == 0) goto done;

    do {
        /* setup the RPC parm structures */
        fidParm.AFSCBFids_len = fidIndex;
        fidParm.AFSCBFids_val = fidsp;
        statParm.AFSBulkStats_len = fidIndex;
        statParm.AFSBulkStats_val = statsp;
        cbParm.AFSCBs_len = fidIndex;
        cbParm.AFSCBs_val = cbsp;

        /* start the timer; callback expirations are relative to this */
        startTime = osi_Time();

        tcp = afs_Conn(&adp->fid, areqp, SHARED_LOCK);
        if (tcp) {
            hostp = tcp->srvr->server;
            XSTATS_START_TIME(AFS_STATS_FS_RPCIDX_BULKSTATUS);
            RX_AFS_GUNLOCK();

            if (!(tcp->srvr->server->flags & SNO_INLINEBULK)) {
                code = RXAFS_InlineBulkStatus(tcp->id, &fidParm, &statParm,
                                              &cbParm, &volSync);
                if (code == RXGEN_OPCODE) {
                    tcp->srvr->server->flags |= SNO_INLINEBULK;
                    inlinebulk = 0;
                    code = RXAFS_BulkStatus(tcp->id, &fidParm, &statParm, 
                                            &cbParm, &volSync);
                } else
                    inlinebulk=1;
            } else {
                inlinebulk=0;
                code = RXAFS_BulkStatus(tcp->id, &fidParm, &statParm, &cbParm,
                                        &volSync);
            }
            RX_AFS_GLOCK();
            XSTATS_END_TIME;
        }
        else code = -1;
    } while (afs_Analyze(tcp, code, &adp->fid, areqp, 
                         AFS_STATS_FS_RPCIDX_BULKSTATUS, SHARED_LOCK, NULL));

    /* now, if we didnt get the info, bail out. */
    if (code) goto done;

    /* we need vol flags to create the entries properly */
    dotdot.Fid.Volume = 0;
    volp = afs_GetVolume(&adp->fid, areqp, READ_LOCK);
    if (volp) {
        volStates = volp->states;
        if (volp->dotdot.Fid.Volume != 0)
            dotdot = volp->dotdot;
    }
    else volStates = 0;

    /* find the place to merge the info into  We do this by skipping
     * nskip entries in the LRU queue.  The more we skip, the more
     * we preserve, since the head of the VLRU queue is the most recently
     * referenced file.
     */
  reskip:
    nskip = afs_cacheStats / 2;         /* preserved fraction of the cache */
    ObtainReadLock(&afs_xvcache);
    if (QEmpty(&VLRU)) {
      /* actually a serious error, probably should panic. Probably will 
       * panic soon, oh well. */
      ReleaseReadLock(&afs_xvcache);
      afs_warnuser("afs_DoBulkStat: VLRU empty!");
      goto done;
    }
    if ((VLRU.next->prev != &VLRU) || (VLRU.prev->next != &VLRU)) {
       refpanic ("Bulkstat VLRU inconsistent");
    }
    for(tq = VLRU.next; tq != &VLRU; tq = QNext(tq)) {
        if (--nskip <= 0) break;
        else if (QNext(QPrev(tq)) != tq) {
           BStvc = QTOV(tq);
           refpanic ("BulkStat VLRU inconsistent");
        }
    }
    if (tq != &VLRU) lruvcp = QTOV(tq);
    else lruvcp = QTOV(VLRU.next);

    /* now we have to hold this entry, so that it does not get moved
     * into the free list while we're running.  It could still get
     * moved within the lru queue, but hopefully that will be rare; it
     * doesn't hurt nearly as much.
     */
    retry = 0;
    osi_vnhold(lruvcp, &retry);
    ReleaseReadLock(&afs_xvcache);           /* could be read lock */
    if (retry)
      goto reskip;

    /* otherwise, merge in the info.  We have to be quite careful here,
     * since we need to ensure that we don't merge old info over newer
     * stuff in a stat cache entry.  We're very conservative here: we don't
     * do the merge at all unless we ourselves create the stat cache
     * entry.  That's pretty safe, and should work pretty well, since we
     * typically expect to do the stat cache creation ourselves.
     *
     * We also have to take into account racing token revocations.
     */
    for(i=0; i<fidIndex; i++) {
        if ((&statsp[i])->errorCode) 
            continue;
        afid.Cell = adp->fid.Cell;
        afid.Fid.Volume = adp->fid.Fid.Volume;
        afid.Fid.Vnode = fidsp[i].Vnode;
        afid.Fid.Unique = fidsp[i].Unique;
        do {
           retry = 0;
           ObtainReadLock(&afs_xvcache);
           tvcp = afs_FindVCache(&afid, &retry, 0/* !stats&!lru*/);
           ReleaseReadLock(&afs_xvcache);
        } while (tvcp && retry);

        /* The entry may no longer exist */
        if (tvcp == NULL) {
            continue;
        }

        /* now we have the entry held, but we need to fill it in */
        ObtainWriteLock(&tvcp->lock,131);

        /* if CBulkFetching is not set, or if the file size no longer
         * matches the value we placed there when we set the CBulkFetching
         * flag, then someone else has done something with this node,
         * and we may not have the latest status information for this
         * file.  Leave the entry alone.
         */
        if (!(tvcp->states & CBulkFetching) || (tvcp->m.Length != statSeqNo)) {
            flagIndex++;
            ReleaseWriteLock(&tvcp->lock);
            afs_PutVCache(tvcp);
            continue;
        }

        /* now copy ".." entry back out of volume structure, if necessary */
        if (tvcp->mvstat == 2  && (dotdot.Fid.Volume != 0)) {
            if (!tvcp->mvid)
                tvcp->mvid = (struct VenusFid *) osi_AllocSmallSpace(sizeof(struct VenusFid));
            *tvcp->mvid = dotdot;
        }

        ObtainWriteLock(&afs_xvcache,132);
        if ((VLRU.next->prev != &VLRU) || (VLRU.prev->next != &VLRU)) {
           refpanic ("Bulkstat VLRU inconsistent2");
        }
        if ((QNext(QPrev(&tvcp->vlruq)) != &tvcp->vlruq) 
            || (QPrev(QNext(&tvcp->vlruq)) != &tvcp->vlruq))
        {   refpanic ("Bulkstat VLRU inconsistent4"); }
        if ((QNext(QPrev(&lruvcp->vlruq)) != &lruvcp->vlruq) 
            || (QPrev(QNext(&lruvcp->vlruq)) != &lruvcp->vlruq)) 
        {   refpanic ("Bulkstat VLRU inconsistent5"); }

        if (tvcp != lruvcp) {  /* if they are == don't move it, don't corrupt vlru */
           QRemove(&tvcp->vlruq);
           QAdd(&lruvcp->vlruq, &tvcp->vlruq);
        }

        if ((VLRU.next->prev != &VLRU) || (VLRU.prev->next != &VLRU)) {
           refpanic ("Bulkstat VLRU inconsistent3");
        }
        if ((QNext(QPrev(&tvcp->vlruq)) != &tvcp->vlruq) 
            || (QPrev(QNext(&tvcp->vlruq)) != &tvcp->vlruq))
        {   refpanic ("Bulkstat VLRU inconsistent5"); }
        if ((QNext(QPrev(&lruvcp->vlruq)) != &lruvcp->vlruq) 
            || (QPrev(QNext(&lruvcp->vlruq)) != &lruvcp->vlruq))
        {   refpanic ("Bulkstat VLRU inconsistent6"); }
        ReleaseWriteLock(&afs_xvcache);

        ObtainWriteLock(&afs_xcbhash, 494);

        /* We need to check the flags again. We may have missed
         * something while we were waiting for a lock.
         */
        if (!(tvcp->states & CBulkFetching) || (tvcp->m.Length != statSeqNo)) {
            flagIndex++;
            ReleaseWriteLock(&tvcp->lock);
            ReleaseWriteLock(&afs_xcbhash);
            afs_PutVCache(tvcp);
            continue;
        }

        /* now merge in the resulting status back into the vnode.
         * We only do this if the entry looks clear.
         */
        afs_ProcessFS(tvcp, &statsp[i], areqp);
#ifdef AFS_LINUX22_ENV
        /* overwrite the ops if it's a directory or symlink. */
        if (vType(tvcp) == VDIR)
            tvcp->v.v_op = &afs_dir_iops;
        else if (vType(tvcp) == VLNK)
            tvcp->v.v_op = &afs_symlink_iops;
#endif

        /* do some accounting for bulk stats: mark this entry as
         * loaded, so we can tell if we use it before it gets
         * recycled.
         */
        tvcp->states |= CBulkStat;
        tvcp->states &= ~CBulkFetching;
        flagIndex++;
        afs_bulkStatsDone++;

        /* merge in vol info */
        if (volStates & VRO) tvcp->states |= CRO;
        if (volStates & VBackup) tvcp->states |= CBackup;
        if (volStates & VForeign) tvcp->states |= CForeign;

        /* merge in the callback info */
        tvcp->states |= CTruth;

        /* get ptr to the callback we are interested in */
        tcbp = cbsp + i;

        if (tcbp->ExpirationTime != 0) {
            tvcp->cbExpires = tcbp->ExpirationTime+startTime;
            tvcp->callback = hostp;
            tvcp->states |= CStatd;
            afs_QueueCallback(tvcp, CBHash(tcbp->ExpirationTime), volp);
        }
        else if (tvcp->states & CRO) {
            /* ordinary callback on a read-only volume -- AFS 3.2 style */
            tvcp->cbExpires = 3600+startTime;
            tvcp->callback = hostp;
            tvcp->states |= CStatd;
            afs_QueueCallback(tvcp, CBHash(3600), volp);
        }
        else {
            tvcp->callback = 0;
            tvcp->states &= ~(CStatd|CUnique);  
            afs_DequeueCallback(tvcp);
            if ((tvcp->states & CForeign) || (vType(tvcp) == VDIR)) 
              osi_dnlc_purgedp (tvcp);  /* if it (could be) a directory */
        }
        ReleaseWriteLock(&afs_xcbhash);

        ReleaseWriteLock(&tvcp->lock);
        /* finally, we're done with the entry */
        afs_PutVCache(tvcp);
    }   /* for all files we got back */

    /* finally return the pointer into the LRU queue */
    afs_PutVCache(lruvcp);

  done:
    /* Be sure to turn off the CBulkFetching flags */
    for(i=flagIndex; i<fidIndex; i++) {
        afid.Cell = adp->fid.Cell;
        afid.Fid.Volume = adp->fid.Fid.Volume;
        afid.Fid.Vnode = fidsp[i].Vnode;
        afid.Fid.Unique = fidsp[i].Unique;
        do {
           retry = 0;
           ObtainReadLock(&afs_xvcache);
           tvcp = afs_FindVCache(&afid, &retry, 0/* !stats&!lru*/);
           ReleaseReadLock(&afs_xvcache);
        } while (tvcp && retry);
        if (tvcp != NULL
            && (tvcp->states & CBulkFetching)
            && (tvcp->m.Length == statSeqNo)) {
          tvcp->states &= ~CBulkFetching;
        }
        if (tvcp != NULL) {
          afs_PutVCache(tvcp);
        }
    }
    if ( volp )
        afs_PutVolume(volp, READ_LOCK);
    
    /* If we did the InlineBulk RPC pull out the return code */
    if (inlinebulk) {
        if ((&statsp[0])->errorCode) {
            afs_Analyze(tcp, (&statsp[0])->errorCode, &adp->fid, areqp, 
                        AFS_STATS_FS_RPCIDX_BULKSTATUS, SHARED_LOCK, 
                        NULL);
            code = (&statsp[0])->errorCode;
        }
    } else {
        code = 0;
    }
    osi_FreeLargeSpace(statMemp);
    osi_FreeLargeSpace(cbfMemp);
    return code;
}

/* was: (AFS_DEC_ENV) || defined(AFS_OSF30_ENV) || defined(AFS_NCR_ENV) */
static int AFSDOBULK = 1;

#ifdef  AFS_OSF_ENV
afs_lookup(adp, ndp)
    struct vcache *adp;
    struct nameidata *ndp; {
    char aname[MAXNAMLEN+1];    /* XXX */
    struct vcache **avcp = (struct vcache **)&(ndp->ni_vp);
    struct ucred *acred = ndp->ni_cred;
    int wantparent = ndp->ni_nameiop & WANTPARENT;
    int opflag = ndp->ni_nameiop & OPFLAG;
#else   /* AFS_OSF_ENV */
#if     defined(AFS_SUN5_ENV) || defined(AFS_SGI_ENV)
afs_lookup(OSI_VC_ARG(adp), aname, avcp, pnp, flags, rdir, acred)
    struct pathname *pnp;
    int flags;
    struct vnode *rdir;
#else
#if defined(UKERNEL)
afs_lookup(adp, aname, avcp, acred, flags)
    int flags;
#else    
afs_lookup(adp, aname, avcp, acred)
#endif /* UKERNEL */
#endif /* SUN5 || SGI */
    OSI_VC_DECL(adp);
    struct vcache **avcp;
    char *aname;
    struct AFS_UCRED *acred; {
#endif
    struct vrequest treq;
    char *tname = NULL;
    register struct vcache *tvc=0;
    register afs_int32 code;
    register afs_int32 bulkcode = 0;
    int pass = 0, hit = 0;
    long dirCookie;
    extern afs_int32 afs_mariner;                       /*Writing activity to log?*/
    OSI_VC_CONVERT(adp)
    afs_hyper_t versionNo;
    int no_read_access = 0;
    struct sysname_info sysState;   /* used only for @sys checking */
    int dynrootRetry = 1;
    struct afs_fakestat_state fakestate;
    int tryEvalOnly = 0;

    AFS_STATCNT(afs_lookup);
    afs_InitFakeStat(&fakestate);

    if ((code = afs_InitReq(&treq, acred)))
        goto done;

#ifdef  AFS_OSF_ENV
    ndp->ni_dvp = AFSTOV(adp);
    memcpy(aname, ndp->ni_ptr, ndp->ni_namelen);
    aname[ndp->ni_namelen] = '\0';
#endif  /* AFS_OSF_ENV */

#if defined(AFS_DARWIN_ENV)
    /* Workaround for MacOSX Finder, which tries to look for
     * .DS_Store and Contents under every directory.
     */
    if (afs_fakestat_enable && adp->mvstat == 1) {
        if (strcmp(aname, ".DS_Store") == 0)
            tryEvalOnly = 1;
        if (strcmp(aname, "Contents") == 0)
            tryEvalOnly = 1;
    }
#endif

    if (tryEvalOnly)
        code = afs_TryEvalFakeStat(&adp, &fakestate, &treq);
    else
        code = afs_EvalFakeStat(&adp, &fakestate, &treq);
    if (tryEvalOnly && adp->mvstat == 1)
        code = ENOENT;
    if (code)
        goto done;

    *avcp = NULL;   /* Since some callers don't initialize it */

    /* come back to here if we encounter a non-existent object in a read-only
       volume's directory */

  redo:
    *avcp = NULL;   /* Since some callers don't initialize it */
    bulkcode = 0;

    if (!(adp->states & CStatd)) {
        if ((code = afs_VerifyVCache2(adp, &treq))) {
            goto done;
        }
    }
    else code = 0;

    /* watch for ".." in a volume root */
    if (adp->mvstat == 2 && aname[0] == '.' && aname[1] == '.' && !aname[2]) {
        /* looking up ".." in root via special hacks */
        if (adp->mvid == (struct VenusFid *) 0 || adp->mvid->Fid.Volume == 0) {
#ifdef  AFS_OSF_ENV
            extern struct vcache *afs_globalVp;
            if (adp == afs_globalVp) {
                struct vnode *rvp = AFSTOV(adp);
/*
                ndp->ni_vp = rvp->v_vfsp->vfs_vnodecovered;
                ndp->ni_dvp = ndp->ni_vp;
                VN_HOLD(*avcp);
*/
                code = ENODEV;
                goto done;
            }
#endif
            code = ENODEV;
            goto done;
        }
        /* otherwise we have the fid here, so we use it */
        tvc = afs_GetVCache(adp->mvid, &treq, NULL, NULL);
        afs_Trace3(afs_iclSetp, CM_TRACE_GETVCDOTDOT,
                   ICL_TYPE_FID, adp->mvid, ICL_TYPE_POINTER, tvc, 
                   ICL_TYPE_INT32,  code);
        *avcp = tvc;
        code = (tvc ? 0 : ENOENT);
        hit = 1;
        if (tvc && !VREFCOUNT(tvc)) {
            osi_Panic("TT1");
        }
        if (code) {
            /*printf("LOOKUP GETVCDOTDOT -> %d\n", code);*/
        }
        goto done;
    }

    /* now check the access */
    if (treq.uid != adp->last_looker) {  
        if (!afs_AccessOK(adp, PRSFS_LOOKUP, &treq, CHECK_MODE_BITS)) {
            *avcp = NULL;
            code = EACCES;
            goto done;
        }
        else adp->last_looker = treq.uid;
    } 

    /* Check for read access as well.  We need read access in order to
       stat files, but not to stat subdirectories. */
    if (!afs_AccessOK(adp, PRSFS_LOOKUP, &treq, CHECK_MODE_BITS))
        no_read_access = 1;

    /* special case lookup of ".".  Can we check for it sooner in this code,
     * for instance, way up before "redo:" ??
     * I'm not fiddling with the LRUQ here, either, perhaps I should, or else 
     * invent a lightweight version of GetVCache.
     */
    if (aname[0] == '.' && !aname[1]) { /* special case */
        ObtainReadLock(&afs_xvcache);   
        osi_vnhold(adp, 0);
        ReleaseReadLock(&afs_xvcache);  
        code = 0;
        *avcp = tvc = adp;
        hit = 1;
        if (adp && !VREFCOUNT(adp)) {
            osi_Panic("TT2");
        }
        goto done;
    }

    Check_AtSys(adp, aname, &sysState, &treq);
    tname = sysState.name;

    /* 1st Check_AtSys and lookup by tname is required here, for now,
       because the dnlc is *not* told to remove entries for the parent
       dir of file/dir op that afs_LocalHero likes, but dnlc is informed
       if the cached entry for the parent dir is invalidated for a
       non-local change.
       Otherwise, we'd be able to do a dnlc lookup on an entry ending
       w/@sys and know the dnlc was consistent with reality. */
    tvc = osi_dnlc_lookup (adp, tname, WRITE_LOCK);
    *avcp = tvc;  /* maybe wasn't initialized, but it is now */
    if (tvc) {
        if (no_read_access && vType(tvc) != VDIR && vType(tvc) != VLNK) {
            /* need read access on dir to stat non-directory / non-link */
            afs_PutVCache(tvc);
            *avcp = NULL;
            code = EACCES;
            goto done;
        }
#ifdef AFS_LINUX22_ENV
        if (tvc->mvstat == 2) { /* we don't trust the dnlc for root vcaches */
            AFS_RELE(tvc);
            *avcp = 0;
        }
        else {  
            code = 0;
            hit = 1;
            goto done;
        }
#else /* non - LINUX */
        code = 0;
        hit = 1;
        goto done;
#endif /* linux22 */
    }

    { /* sub-block just to reduce stack usage */
    register struct dcache *tdc;
    afs_size_t dirOffset, dirLen;
    ino_t theDir;
    struct VenusFid tfid;

    /* now we have to lookup the next fid */
    tdc = afs_GetDCache(adp, (afs_size_t) 0, &treq, &dirOffset, &dirLen, 1);
    if (!tdc) {
        *avcp = NULL;           /* redundant, but harmless */
        code = EIO;
        goto done;
    }

    /* now we will just call dir package with appropriate inode.
      Dirs are always fetched in their entirety for now */
    ObtainReadLock(&adp->lock);
    ObtainReadLock(&tdc->lock);

    /*
     * Make sure that the data in the cache is current. There are two
     * cases we need to worry about:
     * 1. The cache data is being fetched by another process.
     * 2. The cache data is no longer valid
     */
    while ((adp->states & CStatd)
           && (tdc->dflags & DFFetching)
           && hsame(adp->m.DataVersion, tdc->f.versionNo)) {
        ReleaseReadLock(&tdc->lock);
        ReleaseReadLock(&adp->lock);
        afs_osi_Sleep(&tdc->validPos);
        ObtainReadLock(&adp->lock);
        ObtainReadLock(&tdc->lock);
    }
    if (!(adp->states & CStatd)
        || !hsame(adp->m.DataVersion, tdc->f.versionNo)) {
        ReleaseReadLock(&tdc->lock);
        ReleaseReadLock(&adp->lock);
        afs_PutDCache(tdc);
        goto redo;
    }

    /* Save the version number for when we call osi_dnlc_enter */
    hset(versionNo, tdc->f.versionNo);

    /*
     * check for, and handle "@sys" if it's there.  We should be able
     * to avoid the alloc and the strcpy with a little work, but it's
     * not pressing.  If there aren't any remote users (ie, via the 
     * NFS translator), we have a slightly easier job.
     * the faster way to do this is to check for *aname == '@' and if 
     * it's there, check for @sys, otherwise, assume there's no @sys 
     * then, if the lookup fails, check for .*@sys...
     */
    /* above now implemented by Check_AtSys and Next_AtSys */

    /* lookup the name in the appropriate dir, and return a cache entry
       on the resulting fid */
    theDir = tdc->f.inode;
    code = afs_dir_LookupOffset(&theDir, sysState.name, &tfid.Fid, &dirCookie);

    /* If the first lookup doesn't succeed, maybe it's got @sys in the name */
    while (code == ENOENT && Next_AtSys(adp, &treq, &sysState))
        code = afs_dir_LookupOffset(&theDir, sysState.name, &tfid.Fid, &dirCookie);
    tname = sysState.name;

    ReleaseReadLock(&tdc->lock);
    afs_PutDCache(tdc);

    if (code == ENOENT && afs_IsDynroot(adp) && dynrootRetry) {
        ReleaseReadLock(&adp->lock);
        dynrootRetry = 0;
        if (tname[0] == '.')
            afs_LookupAFSDB(tname + 1);
        else
            afs_LookupAFSDB(tname);
        if (tname && tname != aname) osi_FreeLargeSpace(tname);
        goto redo;
    } else {
        ReleaseReadLock(&adp->lock);
    }

    /* new fid has same cell and volume */
    tfid.Cell = adp->fid.Cell;
    tfid.Fid.Volume = adp->fid.Fid.Volume;
    afs_Trace4(afs_iclSetp, CM_TRACE_LOOKUP, ICL_TYPE_POINTER, adp, 
               ICL_TYPE_STRING, tname,
               ICL_TYPE_FID, &tfid, ICL_TYPE_INT32, code);

    if (code) {
        if (code != ENOENT) {
            printf("LOOKUP dirLookupOff -> %d\n", code);
        }
        goto done;
    }  

    /* prefetch some entries, if the dir is currently open.  The variable
     * dirCookie tells us where to start prefetching from.
     */
    if (AFSDOBULK && adp->opens > 0 && !(adp->states & CForeign) && !afs_IsDynroot(adp)) {
        afs_int32 retry;
        /* if the entry is not in the cache, or is in the cache,
         * but hasn't been statd, then do a bulk stat operation.
         */
        do {
            retry = 0;
            ObtainReadLock(&afs_xvcache);       
            tvc = afs_FindVCache(&tfid, &retry, 0 /* !stats,!lru */);
            ReleaseReadLock(&afs_xvcache);      
        } while (tvc && retry);

        if (!tvc || !(tvc->states & CStatd)) 
            bulkcode = afs_DoBulkStat(adp, dirCookie, &treq);
        else 
            bulkcode = 0;

        /* if the vcache isn't usable, release it */
        if (tvc && !(tvc->states & CStatd)) {
            afs_PutVCache(tvc);
            tvc = NULL;
        }
    } else {
        tvc = NULL;
        bulkcode = 0;
    }

    /* now get the status info, if we don't already have it */
    /* This is kind of weird, but we might wind up accidentally calling
     * RXAFS_Lookup because we happened upon a file which legitimately
     * has a 0 uniquifier. That is the result of allowing unique to wrap
     * to 0. This was fixed in AFS 3.4. For CForeign, Unique == 0 means that
     * the file has not yet been looked up.
     */
    if (!tvc) {
        afs_int32 cached = 0;
        if (!tfid.Fid.Unique && (adp->states & CForeign)) {
            tvc = afs_LookupVCache(&tfid, &treq, &cached, adp, tname);
        } 
        if (!tvc && !bulkcode) { /* lookup failed or wasn't called */
            tvc = afs_GetVCache(&tfid, &treq, &cached, NULL);
        } 
    } /* if !tvc */
    } /* sub-block just to reduce stack usage */

    if (tvc) {
        int force_eval = afs_fakestat_enable ? 0 : 1;

        if (adp->states & CForeign)
           tvc->states |= CForeign;
        tvc->parentVnode = adp->fid.Fid.Vnode;
        tvc->parentUnique = adp->fid.Fid.Unique;
        tvc->states &= ~CBulkStat;

        if (afs_fakestat_enable == 2 && tvc->mvstat == 1) {
            ObtainSharedLock(&tvc->lock, 680);
            if (!tvc->linkData) {
                UpgradeSToWLock(&tvc->lock, 681);
                code = afs_HandleLink(tvc, &treq);
                ConvertWToRLock(&tvc->lock);
            } else {
                ConvertSToRLock(&tvc->lock);
                code = 0;
            }
            if (!code && !afs_strchr(tvc->linkData, ':'))
                force_eval = 1;
            ReleaseReadLock(&tvc->lock);
        }

#if defined(UKERNEL) && defined(AFS_WEB_ENHANCEMENTS)
        if (!(flags & AFS_LOOKUP_NOEVAL))
            /* don't eval mount points */
#endif /* UKERNEL && AFS_WEB_ENHANCEMENTS */
        if (tvc->mvstat == 1 && force_eval) {
            /* a mt point, possibly unevaluated */
            struct volume *tvolp;

            ObtainWriteLock(&tvc->lock,133);
            code = EvalMountPoint(tvc, adp, &tvolp, &treq);
            ReleaseWriteLock(&tvc->lock);

            if (code) {
                afs_PutVCache(tvc);
                if (tvolp) afs_PutVolume(tvolp, WRITE_LOCK);
                goto done;
            }

            /* next, we want to continue using the target of the mt point */
            if (tvc->mvid && (tvc->states & CMValid)) {
                struct vcache *uvc;
                /* now lookup target, to set .. pointer */
                afs_Trace2(afs_iclSetp, CM_TRACE_LOOKUP1,
                           ICL_TYPE_POINTER, tvc, ICL_TYPE_FID, &tvc->fid);
                uvc = tvc;      /* remember for later */

                if (tvolp && (tvolp->states & VForeign)) {
                    /* XXXX tvolp has ref cnt on but not locked! XXX */
                    tvc = afs_GetRootVCache(tvc->mvid, &treq, NULL, tvolp);
                } else {
                    tvc = afs_GetVCache(tvc->mvid, &treq, NULL, NULL);
                }
                afs_PutVCache(uvc); /* we're done with it */

                if (!tvc) {
                    code = ENOENT;
                    if (tvolp) {
                        afs_PutVolume(tvolp, WRITE_LOCK);
                    }
                    goto done;
                }

                /* now, if we came via a new mt pt (say because of a new
                 * release of a R/O volume), we must reevaluate the ..
                 * ptr to point back to the appropriate place */
                if (tvolp) {
                    ObtainWriteLock(&tvc->lock,134);
                    if (tvc->mvid == NULL) {
                        tvc->mvid = (struct VenusFid *) osi_AllocSmallSpace(sizeof(struct VenusFid));
                    }
                    /* setup backpointer */
                    *tvc->mvid = tvolp->dotdot;
                    ReleaseWriteLock(&tvc->lock);
                    afs_PutVolume(tvolp, WRITE_LOCK);
                }
            }
            else {
                afs_PutVCache(tvc);
                code = ENOENT;
                if (tvolp) afs_PutVolume(tvolp, WRITE_LOCK);
                goto done;
            }
        }
        *avcp = tvc;
        if (tvc && !VREFCOUNT(tvc)) {
            osi_Panic("TT3");
        }
        code = 0;
    }
    else {
        /* if we get here, we found something in a directory that couldn't
           be located (a Multics "connection failure").  If the volume is
           read-only, we try flushing this entry from the cache and trying
           again. */
        if (pass == 0) {
            struct volume *tv;
            tv = afs_GetVolume(&adp->fid, &treq, READ_LOCK);
            if (tv) {
                if (tv->states & VRO) {
                    pass = 1;                   /* try this *once* */
                    ObtainWriteLock(&afs_xcbhash, 495);
                    afs_DequeueCallback(adp);
                    /* re-stat to get later version */
                    adp->states &= ~CStatd;
                    ReleaseWriteLock(&afs_xcbhash);
                    osi_dnlc_purgedp(adp);
                    afs_PutVolume(tv, READ_LOCK);
                    goto redo;
                }
                afs_PutVolume(tv, READ_LOCK);
            }
        }
        code = ENOENT;
    }

done:
    /* put the network buffer back, if need be */
    if (tname != aname && tname) osi_FreeLargeSpace(tname);
    if (code == 0) {
#ifdef  AFS_OSF_ENV
        /* Handle RENAME; only need to check rename "."  */
        if (opflag == RENAME && wantparent && *ndp->ni_next == 0) {
            if (!FidCmp(&(tvc->fid), &(adp->fid))) { 
                afs_PutVCache(*avcp);
                *avcp = NULL;
                afs_PutFakeStat(&fakestate);
                return afs_CheckCode(EISDIR, &treq, 18);
            }
        }
#endif  /* AFS_OSF_ENV */

        if (afs_mariner)
            afs_AddMarinerName(aname, tvc); 

#if defined(UKERNEL) && defined(AFS_WEB_ENHANCEMENTS)
        if (!(flags & AFS_LOOKUP_NOEVAL))
        /* Here we don't enter the name into the DNLC because we want the
        evaluated mount dir to be there (the vcache for the mounted volume)
        rather than the vc of the mount point itself.  we can still find the
        mount point's vc in the vcache by its fid. */
#endif /* UKERNEL && AFS_WEB_ENHANCEMENTS */
        if (!hit) {
            osi_dnlc_enter (adp, aname, tvc, &versionNo);
        }
        else {
#ifdef AFS_LINUX20_ENV
            /* So Linux inode cache is up to date. */
            code = afs_VerifyVCache(tvc, &treq);
#else
            afs_PutFakeStat(&fakestate);
            return 0;  /* can't have been any errors if hit and !code */
#endif
        }
    }
    if (bulkcode) code = bulkcode; else 
    code = afs_CheckCode(code, &treq, 19);
    if (code) {
        /* If there is an error, make sure *avcp is null.
         * Alphas panic otherwise - defect 10719.
         */
        *avcp = NULL;
    }

    afs_PutFakeStat(&fakestate);
    return code;
}