xnu-124.13.tar.gz

[apple/xnu.git] / bsd / hfs / hfs_readwrite.c

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*	@(#)hfs_readwrite.c	1.0
 *
 *	(c) 1990, 1992 NeXT Computer, Inc.  All Rights Reserved
 *	(c) 1998       Apple Computer, Inc.  All Rights Reserved
 *	
 *
 *	hfs_readwrite.c -- vnode operations to deal with reading and writing files.
 *
 *	MODIFICATION HISTORY:
 *	 9-Nov-1999	Scott Roberts	hfs_allocate now returns sizes based on allocation block boundaries (#2398794)
 *	 3-Feb-1999	Pat Dirks		Merged in Joe's change to hfs_truncate to skip vinvalbuf if LEOF isn't changing (#2302796)
 *								Removed superfluous (and potentially dangerous) second call to vinvalbuf() in hfs_truncate.
 *	 2-Dec-1998	Pat Dirks		Added support for read/write bootstrap ioctls.
 *	10-Nov-1998	Pat Dirks		Changed read/write/truncate logic to optimize block sizes for first extents of a file.
 *                              Changed hfs_strategy to correct I/O sizes from cluser code I/O requests in light of
 *                              different block sizing.  Changed bexpand to handle RELEASE_BUFFER flag.
 *	22-Sep-1998	Don Brady		Changed truncate zero-fill to use bwrite after several bawrites have been queued.
 *	11-Sep-1998	Pat Dirks		Fixed buffering logic to not rely on B_CACHE, which is set for empty buffers that
 *								have been pre-read by cluster_read (use b_validend > 0 instead).
 *  27-Aug-1998	Pat Dirks		Changed hfs_truncate to use cluster_write in place of bawrite where possible.
 *	25-Aug-1998	Pat Dirks		Changed hfs_write to do small device-block aligned writes into buffers without doing
 *								read-ahead of the buffer.  Added bexpand to deal with incomplete [dirty] buffers.
 *								Fixed can_cluster macro to use MAXPHYSIO instead of MAXBSIZE.
 *	19-Aug-1998	Don Brady		Remove optimization in hfs_truncate that prevented extra physical blocks from
 *								being truncated (radar #2265750). Also set fcb->fcbEOF before calling vinvalbuf.
 *	 7-Jul-1998	Pat Dirks		Added code to honor IO_NOZEROFILL in hfs_truncate.
 *	16-Jul-1998	Don Brady		In hfs_bmap use MAXPHYSIO instead of MAXBSIZE when calling MapFileBlockC (radar #2263753).
 *	16-Jul-1998	Don Brady		Fix error handling in hfs_allocate (radar #2252265).
 *	04-Jul-1998	chw				Synchronized options in hfs_allocate with flags in call to ExtendFileC
 *	25-Jun-1998	Don Brady		Add missing blockNo incrementing to zero fill loop in hfs_truncate.
 *	22-Jun-1998	Don Brady		Add bp = NULL assignment after brelse in hfs_read.
 *	 4-Jun-1998	Pat Dirks		Split off from hfs_vnodeops.c
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/resourcevar.h>
#include <sys/kernel.h>
#include <sys/fcntl.h>
#include <sys/stat.h>
#include <sys/buf.h>
#include <sys/proc.h>
//#include <mach/machine/vm_types.h>
#include <sys/vnode.h>
#include <sys/uio.h>

#include <miscfs/specfs/specdev.h>


#include <sys/ubc.h>
#include <vm/vm_pageout.h>


#include <sys/kdebug.h>

#include	"hfs.h"
#include	"hfs_dbg.h"
#include	"hfs_endian.h"
#include	"hfscommon/headers/FileMgrInternal.h"
#include	"hfscommon/headers/BTreesInternal.h"


#define can_cluster(size) ((((size & (4096-1))) == 0) && (size <= (MAXPHYSIO/2)))

enum {
	MAXHFSFILESIZE = 0x7FFFFFFF		/* this needs to go in the mount structure */
};

extern u_int32_t GetLogicalBlockSize(struct vnode *vp);

#if DBG_VOP_TEST_LOCKS
extern void DbgVopTest(int maxSlots, int retval, VopDbgStoreRec *VopDbgStore, char *funcname);
#endif

#if HFS_DIAGNOSTIC
void debug_check_blocksizes(struct vnode *vp);
#endif

/*****************************************************************************
*
*	Operations on vnodes
*
*****************************************************************************/

/*
#% read		vp	L L L
#
 vop_read {
     IN struct vnode *vp;
     INOUT struct uio *uio;
     IN int ioflag;
     IN struct ucred *cred;

     */

int
hfs_read(ap)
struct vop_read_args /* {
    struct vnode *a_vp;
    struct uio *a_uio;
    int a_ioflag;
    struct ucred *a_cred;
} */ *ap;
{
    register struct vnode 	*vp;
    struct hfsnode 			*hp;
    register struct uio 	*uio;
    struct buf 				*bp;
    daddr_t 				logBlockNo;
    u_long					fragSize, moveSize, startOffset, ioxfersize;
    long					devBlockSize = 0;
    off_t 					bytesRemaining;
    int 					retval;
    u_short 				mode;
    FCB						*fcb;

    DBG_FUNC_NAME("hfs_read");
    DBG_VOP_LOCKS_DECL(1);
    DBG_VOP_PRINT_FUNCNAME();
    DBG_VOP_PRINT_VNODE_INFO(ap->a_vp);DBG_VOP_CONT(("\n"));
    DBG_VOP_LOCKS_INIT(0,ap->a_vp, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_POS);

    vp = ap->a_vp;
    hp = VTOH(vp);
    fcb = HTOFCB(hp);
    mode = hp->h_meta->h_mode;
    uio = ap->a_uio;

#if HFS_DIAGNOSTIC
    if (uio->uio_rw != UIO_READ)
        panic("%s: mode", funcname);
#endif

    /* Can only read files */
    if (ap->a_vp->v_type != VREG && ap->a_vp->v_type != VLNK) {
        DBG_VOP_LOCKS_TEST(EISDIR);
        return (EISDIR);
    }
    DBG_RW(("\tfile size Ox%X\n", (u_int)fcb->fcbEOF));
    DBG_RW(("\tstarting at offset Ox%X of file, length Ox%X\n", (u_int)uio->uio_offset, (u_int)uio->uio_resid));

#if HFS_DIAGNOSTIC
    debug_check_blocksizes(vp);
#endif

    /*
     * If they didn't ask for any data, then we are done.
     */
    if (uio->uio_resid == 0) {
        DBG_VOP_LOCKS_TEST(E_NONE);
        return (E_NONE);
    }

    /* cant read from a negative offset */
    if (uio->uio_offset < 0) {
        DBG_VOP_LOCKS_TEST(EINVAL);
        return (EINVAL);
    }

    if (uio->uio_offset > fcb->fcbEOF) {
        if ( (!ISHFSPLUS(VTOVCB(vp))) && (uio->uio_offset > (off_t)MAXHFSFILESIZE))
            retval = EFBIG;
        else
            retval = E_NONE;

        DBG_VOP_LOCKS_TEST(retval);
        return (retval);
    }

    VOP_DEVBLOCKSIZE(hp->h_meta->h_devvp, &devBlockSize);

    KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 12)) | DBG_FUNC_START,
                 (int)uio->uio_offset, uio->uio_resid, (int)fcb->fcbEOF,  (int)fcb->fcbPLen, 0);

    if (UBCISVALID(vp))
        retval = cluster_read(vp, uio, (off_t)fcb->fcbEOF, devBlockSize, 0);
    else {

        for (retval = 0, bp = NULL; uio->uio_resid > 0; bp = NULL) {

            if ((bytesRemaining = (fcb->fcbEOF - uio->uio_offset)) <= 0)
                break;

            logBlockNo  = (daddr_t)(uio->uio_offset / PAGE_SIZE_64);
            startOffset = (u_long) (uio->uio_offset & PAGE_MASK_64);
            fragSize    = PAGE_SIZE;

            if (((logBlockNo * PAGE_SIZE) + fragSize) < fcb->fcbEOF)
                ioxfersize = fragSize;
            else {
                ioxfersize = fcb->fcbEOF - (logBlockNo * PAGE_SIZE);
                ioxfersize = (ioxfersize + (devBlockSize - 1)) & ~(devBlockSize - 1);
            }
            DBG_RW(("\tat logBlockNo Ox%X, with Ox%lX left to read\n", logBlockNo, (UInt32)uio->uio_resid));
            moveSize = ioxfersize;
            DBG_RW(("\tmoveSize = Ox%lX; ioxfersize = Ox%lX; startOffset = Ox%lX.\n",
                    moveSize, ioxfersize, startOffset));
            DBG_ASSERT(moveSize >= startOffset);
            moveSize -= startOffset;

            if (bytesRemaining < moveSize)
                moveSize = bytesRemaining;

            if (uio->uio_resid < moveSize) {
                moveSize = uio->uio_resid;
                DBG_RW(("\treducing moveSize to Ox%lX (uio->uio_resid).\n", moveSize));
            };
            if (moveSize == 0) {
                break;
            };

            DBG_RW(("\tat logBlockNo Ox%X, extent of Ox%lX, xfer of Ox%lX; moveSize = Ox%lX\n", logBlockNo, fragSize, ioxfersize, moveSize));

            if (( uio->uio_offset + fragSize) >= fcb->fcbEOF) {
                retval = bread(vp, logBlockNo, ioxfersize, NOCRED, &bp);

            } else if (logBlockNo - 1 == vp->v_lastr && !(vp->v_flag & VRAOFF)) {
                daddr_t nextLogBlockNo = logBlockNo + 1;
                int nextsize;

                if (((nextLogBlockNo * PAGE_SIZE) +
                     (daddr_t)fragSize) < fcb->fcbEOF)
                    nextsize = fragSize;
                else {
                    nextsize = fcb->fcbEOF - (nextLogBlockNo * PAGE_SIZE);
                    nextsize = (nextsize + (devBlockSize - 1)) & ~(devBlockSize - 1);
                }
                retval = breadn(vp, logBlockNo, ioxfersize, &nextLogBlockNo, &nextsize, 1, NOCRED, &bp);
            } else {
                retval = bread(vp, logBlockNo, ioxfersize, NOCRED, &bp);
            };

            if (retval != E_NONE) {
                if (bp) {
                    brelse(bp);
                    bp = NULL;
                }
                break;
            };
            vp->v_lastr = logBlockNo;

            /*
             * We should only get non-zero b_resid when an I/O retval
             * has occurred, which should cause us to break above.
             * However, if the short read did not cause an retval,
             * then we want to ensure that we do not uiomove bad
             * or uninitialized data.
             */
            ioxfersize -= bp->b_resid;

            if (ioxfersize < moveSize) {			/* XXX PPD This should take the offset into account, too! */
                if (ioxfersize == 0)
                    break;
                moveSize = ioxfersize;
            }
            if ((startOffset + moveSize) > bp->b_bcount)
                panic("hfs_read: bad startOffset or moveSize\n");

            DBG_RW(("\tcopying Ox%lX bytes from %lX; resid = Ox%lX...\n", moveSize, (char *)bp->b_data + startOffset, bp->b_resid));

            if ((retval = uiomove((caddr_t)bp->b_data + startOffset, (int)moveSize, uio)))
                break;

            if (S_ISREG(mode) &&
                (((startOffset + moveSize) == fragSize) || (uio->uio_offset == fcb->fcbEOF))) {
                bp->b_flags |= B_AGE;
            };

            DBG_ASSERT(bp->b_bcount == bp->b_validend);

            brelse(bp);
            /* Start of loop resets bp to NULL before reaching outside this block... */
        }

        if (bp != NULL) {
            DBG_ASSERT(bp->b_bcount == bp->b_validend);
            brelse(bp);
        };
    }

    if (HTOVCB(hp)->vcbSigWord == kHFSPlusSigWord)
        hp->h_nodeflags |= IN_ACCESS;

    DBG_VOP_LOCKS_TEST(retval);

    #if HFS_DIAGNOSTIC
        debug_check_blocksizes(vp);
    #endif

    KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 12)) | DBG_FUNC_END,
                (int)uio->uio_offset, uio->uio_resid, (int)fcb->fcbEOF,  (int)fcb->fcbPLen, 0);

    return (retval);
}

/*
 * Write data to a file or directory.
#% write	vp	L L L
#
 vop_write {
     IN struct vnode *vp;
     INOUT struct uio *uio;
     IN int ioflag;
     IN struct ucred *cred;

     */
int
hfs_write(ap)
struct vop_write_args /* {
    struct vnode *a_vp;
    struct uio *a_uio;
    int a_ioflag;
    struct ucred *a_cred;
} */ *ap;
{
    struct hfsnode 		*hp = VTOH(ap->a_vp);
    struct uio 			*uio = ap->a_uio;
    struct vnode 		*vp = ap->a_vp ;
    struct vnode 		*dev;
    struct buf 			*bp;
    struct proc 		*p, *cp;
    struct timeval tv;
    FCB					*fcb = HTOFCB(hp);
    ExtendedVCB			*vcb = HTOVCB(hp);
    long				devBlockSize = 0;
    daddr_t 			logBlockNo;
    long				fragSize;
    off_t 				origFileSize, currOffset, writelimit, bytesToAdd;
    off_t				actualBytesAdded;
    u_long				blkoffset, resid, xfersize, clearSize;
    int					flags, ioflag;
    int 				retval;
    DBG_FUNC_NAME("hfs_write");
    DBG_VOP_LOCKS_DECL(1);
    DBG_VOP_PRINT_FUNCNAME();
    DBG_VOP_PRINT_VNODE_INFO(ap->a_vp);DBG_VOP_CONT(("\n"));
    DBG_RW(("\thfsnode 0x%x (%s)\n", (u_int)hp, H_NAME(hp)));
    DBG_RW(("\tstarting at offset Ox%lX of file, length Ox%lX\n", (UInt32)uio->uio_offset, (UInt32)uio->uio_resid));

    DBG_VOP_LOCKS_INIT(0,ap->a_vp, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_POS);

    dev = hp->h_meta->h_devvp;

#if HFS_DIAGNOSTIC
    debug_check_blocksizes(vp);
#endif

    if (uio->uio_offset < 0) {
        DBG_VOP_LOCKS_TEST(EINVAL);
        return (EINVAL);
    }

    if (uio->uio_resid == 0) {
        DBG_VOP_LOCKS_TEST(E_NONE);
        return (E_NONE);
    }

    if (ap->a_vp->v_type != VREG && ap->a_vp->v_type != VLNK) {		/* Can only write files */
        DBG_VOP_LOCKS_TEST(EISDIR);
        return (EISDIR);
    };

#if HFS_DIAGNOSTIC
	if (uio->uio_rw != UIO_WRITE)
		panic("%s: mode", funcname);
#endif

    ioflag = ap->a_ioflag;
    uio = ap->a_uio;
    vp = ap->a_vp;

    if (ioflag & IO_APPEND)
    	uio->uio_offset = fcb->fcbEOF;
    if ((hp->h_meta->h_pflags & APPEND) && uio->uio_offset != fcb->fcbEOF)
    	return (EPERM);

	writelimit = uio->uio_offset + uio->uio_resid;

    /*
    * Maybe this should be above the vnode op call, but so long as
    * file servers have no limits, I don't think it matters.
    */
    p = uio->uio_procp;
    if (vp->v_type == VREG && p &&
        writelimit > p->p_rlimit[RLIMIT_FSIZE].rlim_cur) {
        psignal(p, SIGXFSZ);
        return (EFBIG);
    };
    VOP_DEVBLOCKSIZE(hp->h_meta->h_devvp, &devBlockSize);

    resid = uio->uio_resid;
    origFileSize = fcb->fcbPLen;
    flags = ioflag & IO_SYNC ? B_SYNC : 0;

    DBG_RW(("\tLEOF is 0x%lX, PEOF is 0x%lX.\n", fcb->fcbEOF, fcb->fcbPLen));

    /*
    NOTE:	In the following loop there are two positions tracked:
    currOffset is the current I/O starting offset.  currOffset is never >LEOF; the
    LEOF is nudged along with currOffset as data is zeroed or written.
    uio->uio_offset is the start of the current I/O operation.  It may be arbitrarily
    beyond currOffset.

    The following is true at all times:

    currOffset <= LEOF <= uio->uio_offset <= writelimit
    */
    currOffset = MIN(uio->uio_offset, fcb->fcbEOF);

    DBG_RW(("\tstarting I/O loop at 0x%lX.\n", (u_long)currOffset));

    cp = current_proc();

    KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 0)) | DBG_FUNC_START,
                (int)uio->uio_offset, uio->uio_resid, (int)fcb->fcbEOF,  (int)fcb->fcbPLen, 0);
    retval = 0;

    if (fcb->fcbEOF > fcb->fcbMaxEOF)
        fcb->fcbMaxEOF = fcb->fcbEOF;

    /* Now test if we need to extend the file */
    /* Doing so will adjust the fcbPLen for us */

    while (writelimit > (off_t)fcb->fcbPLen) {
	
        bytesToAdd = writelimit - fcb->fcbPLen;
        DBG_RW(("\textending file by 0x%lX bytes; 0x%lX blocks free",
                (unsigned long)bytesToAdd, (unsigned long)vcb->freeBlocks));

        /* lock extents b-tree (also protects volume bitmap) */
        retval = hfs_metafilelocking(HTOHFS(hp), kHFSExtentsFileID, LK_EXCLUSIVE, cp);
        if (retval != E_NONE)
            break;

        retval = MacToVFSError(
                            ExtendFileC (vcb,
                                            fcb,
                                            bytesToAdd,
                                            kEFContigBit,
                                            &actualBytesAdded));

        (void) hfs_metafilelocking(HTOHFS(hp), kHFSExtentsFileID, LK_RELEASE, cp);
        DBG_VOP_CONT(("\tactual bytes added = 0x%lX bytes, retval = %d...\n", actualBytesAdded, retval));
        if ((actualBytesAdded == 0) && (retval == E_NONE))
            retval = ENOSPC;
        if (retval != E_NONE)
            break;

        KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 0)) | DBG_FUNC_NONE,
                    (int)uio->uio_offset, uio->uio_resid, (int)fcb->fcbEOF,  (int)fcb->fcbPLen, 0);
    };

    if (UBCISVALID(vp) && retval == E_NONE) {
	  off_t filesize;
	  off_t zero_off;
	  int   lflag;

	  if (writelimit > fcb->fcbEOF)
	      filesize = writelimit;
	  else
	      filesize = fcb->fcbEOF;

	  lflag = (ioflag & IO_SYNC);

	  if (uio->uio_offset > fcb->fcbMaxEOF) {
	      zero_off = fcb->fcbMaxEOF;
	      lflag   |= IO_HEADZEROFILL;
	  } else
	      zero_off = 0;

	  /*
	   * if the write starts beyond the current EOF then
	   * we we'll zero fill from the current EOF to where the write begins
	   */
          retval = cluster_write(vp, uio, fcb->fcbEOF, filesize, zero_off,
				 (off_t)0, devBlockSize, lflag);

	  if (uio->uio_offset > fcb->fcbEOF) {
	      fcb->fcbEOF = uio->uio_offset;

	      if (fcb->fcbEOF > fcb->fcbMaxEOF)
		  fcb->fcbMaxEOF = fcb->fcbEOF;

	      ubc_setsize(vp, (off_t)fcb->fcbEOF);       /* XXX check errors */
	  }
	  if (resid > uio->uio_resid)
	      hp->h_nodeflags |= IN_CHANGE | IN_UPDATE;

    } else {

        while (retval == E_NONE && uio->uio_resid > 0) {

            logBlockNo = currOffset / PAGE_SIZE;
            blkoffset  = currOffset & PAGE_MASK;

            if (((off_t)(fcb->fcbPLen) - currOffset) < PAGE_SIZE_64)
                fragSize = (off_t)(fcb->fcbPLen) - ((off_t)logBlockNo * PAGE_SIZE_64);
            else
                fragSize = PAGE_SIZE;
            xfersize = fragSize - blkoffset;

            DBG_RW(("\tcurrOffset = Ox%lX, logBlockNo = Ox%X, blkoffset = Ox%lX, xfersize = Ox%lX, fragSize = Ox%lX.\n",
                    (unsigned long)currOffset, logBlockNo, blkoffset, xfersize, fragSize));

            /* Make any adjustments for boundary conditions */
            if (currOffset + (off_t)xfersize > writelimit) {
                xfersize = writelimit - currOffset;
                DBG_RW(("\ttrimming xfersize to 0x%lX to match writelimit (uio_resid)...\n", xfersize));
            };

            /*
            * There is no need to read into bp if:
            * We start on a block boundary and will overwrite the whole block
            *
            *						OR
            */
            if ((blkoffset == 0) && (xfersize >= fragSize)) {
                DBG_RW(("\tRequesting %ld-byte block Ox%lX w/o read...\n", fragSize, (long)logBlockNo));

                bp = getblk(vp, logBlockNo, fragSize, 0, 0, BLK_READ);
                retval = 0;

                if (bp->b_blkno == -1) {
                    brelse(bp);
                    retval = EIO;		/* XXX */
                    break;
                }
            } else {

                if (currOffset == fcb->fcbEOF && blkoffset == 0) {
                    bp = getblk(vp, logBlockNo, fragSize, 0, 0, BLK_READ);
                    retval = 0;

                    if (bp->b_blkno == -1) {
                        brelse(bp);
                        retval = EIO;		/* XXX */
                        break;
                    }

                } else {
                    /*
                    * This I/O transfer is not sufficiently aligned, so read the affected block into a buffer:
                    */
                    DBG_VOP(("\tRequesting block Ox%X, size = 0x%08lX...\n", logBlockNo, fragSize));
                    retval = bread(vp, logBlockNo, fragSize, ap->a_cred, &bp);

                    if (retval != E_NONE) {
                        if (bp)
                            brelse(bp);
                        break;
                    }
                }
            }

            /* See if we are starting to write within file boundaries:
                If not, then we need to present a "hole" for the area between
                the current EOF and the start of the current I/O operation:

                Note that currOffset is only less than uio_offset if uio_offset > LEOF...
                */
            if (uio->uio_offset > currOffset) {
                clearSize = MIN(uio->uio_offset - currOffset, xfersize);
                DBG_RW(("\tzeroing Ox%lX bytes Ox%lX bytes into block Ox%X...\n", clearSize, blkoffset, logBlockNo));
                bzero(bp->b_data + blkoffset, clearSize);
                currOffset += clearSize;
                blkoffset += clearSize;
                xfersize -= clearSize;
            };

            if (xfersize > 0) {
                DBG_RW(("\tCopying Ox%lX bytes Ox%lX bytes into block Ox%X... ioflag == 0x%X\n",
                        xfersize, blkoffset, logBlockNo, ioflag));
                retval = uiomove((caddr_t)bp->b_data + blkoffset, (int)xfersize, uio);
                currOffset += xfersize;
            };
            DBG_ASSERT((bp->b_bcount % devBlockSize) == 0);

            if (ioflag & IO_SYNC) {
                (void)VOP_BWRITE(bp);
                //DBG_RW(("\tissuing bwrite\n"));
            } else if ((xfersize + blkoffset) == fragSize) {
                //DBG_RW(("\tissuing bawrite\n"));
                bp->b_flags |= B_AGE;
                bawrite(bp);
            } else {
                //DBG_RW(("\tissuing bdwrite\n"));
                bdwrite(bp);
            };

            /* Update the EOF if we just extended the file
                (the PEOF has already been moved out and the block mapping table has been updated): */
            if (currOffset > fcb->fcbEOF) {
                DBG_VOP(("\textending EOF to 0x%lX...\n", (UInt32)fcb->fcbEOF));
                fcb->fcbEOF = currOffset;

                if (fcb->fcbEOF > fcb->fcbMaxEOF)
			        fcb->fcbMaxEOF = fcb->fcbEOF;

                if (UBCISVALID(vp))
                    ubc_setsize(vp, (off_t)fcb->fcbEOF); /* XXX check errors */
            };

            if (retval || (resid == 0))
                break;
            hp->h_nodeflags |= IN_CHANGE | IN_UPDATE;
        };
    };
    /*
    * If we successfully wrote any data, and we are not the superuser
    * we clear the setuid and setgid bits as a precaution against
    * tampering.
    */
    if (resid > uio->uio_resid && ap->a_cred && ap->a_cred->cr_uid != 0)
    hp->h_meta->h_mode &= ~(ISUID | ISGID);

    if (retval) {
        if (ioflag & IO_UNIT) {
            (void)VOP_TRUNCATE(vp, origFileSize,
                            ioflag & IO_SYNC, ap->a_cred, uio->uio_procp);
            uio->uio_offset -= resid - uio->uio_resid;
            uio->uio_resid = resid;
        }
    } else if (resid > uio->uio_resid && (ioflag & IO_SYNC)) {
        tv = time;
        retval = VOP_UPDATE(vp, &tv, &tv, 1);
    }

    #if HFS_DIAGNOSTIC
    debug_check_blocksizes(vp);
    #endif

    KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 0)) | DBG_FUNC_END,
                (int)uio->uio_offset, uio->uio_resid, (int)fcb->fcbEOF, (int)fcb->fcbPLen, 0);

    DBG_VOP_LOCKS_TEST(retval);
    return (retval);
}


/*

#% ioctl	vp	U U U
#
 vop_ioctl {
     IN struct vnode *vp;
     IN u_long command;
     IN caddr_t data;
     IN int fflag;
     IN struct ucred *cred;
     IN struct proc *p;

     */


/* ARGSUSED */
int
hfs_ioctl(ap)
struct vop_ioctl_args /* {
    struct vnode *a_vp;
    int  a_command;
    caddr_t  a_data;
    int  a_fflag;
    struct ucred *a_cred;
    struct proc *a_p;
} */ *ap;
{
    DBG_FUNC_NAME("hfs_ioctl");
    DBG_VOP_LOCKS_DECL(1);
    DBG_VOP_PRINT_FUNCNAME();
    DBG_VOP_PRINT_VNODE_INFO(ap->a_vp);DBG_VOP_CONT(("\n"));

    DBG_VOP_LOCKS_INIT(0,ap->a_vp, VOPDBG_UNLOCKED, VOPDBG_UNLOCKED, VOPDBG_UNLOCKED, VOPDBG_POS);

    switch (ap->a_command) {
	
    case 1:
    {   register struct hfsnode *hp;
        register struct vnode *vp;
	register struct radvisory *ra;
	FCB *fcb;
	int devBlockSize = 0;
	int error;

	vp = ap->a_vp;

	VOP_LEASE(vp, ap->a_p, ap->a_cred, LEASE_READ);
	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, ap->a_p);

	ra = (struct radvisory *)(ap->a_data);
	hp = VTOH(vp);

	fcb = HTOFCB(hp);

	if (ra->ra_offset >= fcb->fcbEOF) {
	    VOP_UNLOCK(vp, 0, ap->a_p);
	    DBG_VOP_LOCKS_TEST(EFBIG);
	    return (EFBIG);
	}
	VOP_DEVBLOCKSIZE(hp->h_meta->h_devvp, &devBlockSize);

	error = advisory_read(vp, fcb->fcbEOF, ra->ra_offset, ra->ra_count, devBlockSize);
	VOP_UNLOCK(vp, 0, ap->a_p);

	DBG_VOP_LOCKS_TEST(error);
	return (error);
    }

    case 2: /* F_READBOOTBLOCKS */
    case 3: /* F_WRITEBOOTBLOCKS */
      {
	    struct vnode *vp = ap->a_vp;
	    struct hfsnode *hp = VTOH(vp);
	    struct fbootstraptransfer *btd = (struct fbootstraptransfer *)ap->a_data;
	    u_long devBlockSize;
	    int error;
	    struct iovec aiov;
	    struct uio auio;
	    u_long blockNumber;
	    u_long blockOffset;
	    u_long xfersize;
	    struct buf *bp;

        if ((vp->v_flag & VROOT) == 0) return EINVAL;
        if (btd->fbt_offset + btd->fbt_length > 1024) return EINVAL;
	    
	    aiov.iov_base = btd->fbt_buffer;
	    aiov.iov_len = btd->fbt_length;
	    
	    auio.uio_iov = &aiov;
	    auio.uio_iovcnt = 1;
	    auio.uio_offset = btd->fbt_offset;
	    auio.uio_resid = btd->fbt_length;
	    auio.uio_segflg = UIO_USERSPACE;
	    auio.uio_rw = (ap->a_command == 3) ? UIO_WRITE : UIO_READ; /* F_WRITEBOOTSTRAP / F_READBOOTSTRAP */
	    auio.uio_procp = ap->a_p;

	    VOP_DEVBLOCKSIZE(hp->h_meta->h_devvp, &devBlockSize);

	    while (auio.uio_resid > 0) {
	      blockNumber = auio.uio_offset / devBlockSize;
	      error = bread(hp->h_meta->h_devvp, blockNumber, devBlockSize, ap->a_cred, &bp);
	      if (error) {
              if (bp) brelse(bp);
              return error;
          };

          blockOffset = auio.uio_offset % devBlockSize;
	      xfersize = devBlockSize - blockOffset;
	      error = uiomove((caddr_t)bp->b_data + blockOffset, (int)xfersize, &auio);
          if (error) {
              brelse(bp);
              return error;
          };
          if (auio.uio_rw == UIO_WRITE) {
              error = VOP_BWRITE(bp);
              if (error) return error;
          } else {
              brelse(bp);
          };
        };
      };
      return 0;

    default:
        DBG_VOP_LOCKS_TEST(ENOTTY);
        return (ENOTTY);
    }

    return 0;
}

/* ARGSUSED */
int
hfs_select(ap)
struct vop_select_args /* {
    struct vnode *a_vp;
    int  a_which;
    int  a_fflags;
    struct ucred *a_cred;
    struct proc *a_p;
} */ *ap;
{
    DBG_FUNC_NAME("hfs_select");
    DBG_VOP_LOCKS_DECL(1);
    DBG_VOP_PRINT_FUNCNAME();
    DBG_VOP_PRINT_VNODE_INFO(ap->a_vp);DBG_VOP_CONT(("\n"));

    DBG_VOP_LOCKS_INIT(0,ap->a_vp, VOPDBG_LOCKED, VOPDBG_IGNORE, VOPDBG_IGNORE, VOPDBG_POS);

    /*
     * We should really check to see if I/O is possible.
     */
    DBG_VOP_LOCKS_TEST(1);
    return (1);
}



/*
 * Mmap a file
 *
 * NB Currently unsupported.
# XXX - not used
#
 vop_mmap {
     IN struct vnode *vp;
     IN int fflags;
     IN struct ucred *cred;
     IN struct proc *p;

     */

/* ARGSUSED */

int
hfs_mmap(ap)
struct vop_mmap_args /* {
    struct vnode *a_vp;
    int  a_fflags;
    struct ucred *a_cred;
    struct proc *a_p;
} */ *ap;
{
    DBG_FUNC_NAME("hfs_mmap");
    DBG_VOP_LOCKS_DECL(1);
    DBG_VOP_PRINT_FUNCNAME();
    DBG_VOP_PRINT_VNODE_INFO(ap->a_vp);DBG_VOP_CONT(("\n"));

    DBG_VOP_LOCKS_INIT(0,ap->a_vp, VOPDBG_IGNORE, VOPDBG_IGNORE, VOPDBG_IGNORE, VOPDBG_POS);

    DBG_VOP_LOCKS_TEST(EINVAL);
    return (EINVAL);
}



/*
 * Seek on a file
 *
 * Nothing to do, so just return.
# XXX - not used
# Needs work: Is newoff right?  What's it mean?
#
 vop_seek {
     IN struct vnode *vp;
     IN off_t oldoff;
     IN off_t newoff;
     IN struct ucred *cred;
     */
/* ARGSUSED */
int
hfs_seek(ap)
struct vop_seek_args /* {
    struct vnode *a_vp;
    off_t  a_oldoff;
    off_t  a_newoff;
    struct ucred *a_cred;
} */ *ap;
{
    DBG_FUNC_NAME("hfs_seek");
    DBG_VOP_LOCKS_DECL(1);
    DBG_VOP_PRINT_FUNCNAME();
    DBG_VOP_PRINT_VNODE_INFO(ap->a_vp);DBG_VOP_CONT(("\n"));

    DBG_VOP_LOCKS_INIT(0,ap->a_vp, VOPDBG_IGNORE, VOPDBG_IGNORE, VOPDBG_IGNORE, VOPDBG_POS);

    DBG_VOP_LOCKS_TEST(E_NONE);
    return (E_NONE);
}


/*
 * Bmap converts a the logical block number of a file to its physical block
 * number on the disk.
 */

/*
 * vp  - address of vnode file the file
 * bn  - which logical block to convert to a physical block number.
 * vpp - returns the vnode for the block special file holding the filesystem
 *	 containing the file of interest
 * bnp - address of where to return the filesystem physical block number
#% bmap		vp	L L L
#% bmap		vpp	- U -
#
 vop_bmap {
     IN struct vnode *vp;
     IN daddr_t bn;
     OUT struct vnode **vpp;
     IN daddr_t *bnp;
     OUT int *runp;
     */
/*
 * Converts a logical block number to a physical block, and optionally returns
 * the amount of remaining blocks in a run. The logical block is based on hfsNode.logBlockSize.
 * The physical block number is based on the device block size, currently its 512.
 * The block run is returned in logical blocks, and is the REMAINING amount of blocks
 */

int
hfs_bmap(ap)
struct vop_bmap_args /* {
    struct vnode *a_vp;
    daddr_t a_bn;
    struct vnode **a_vpp;
    daddr_t *a_bnp;
    int *a_runp;
} */ *ap;
{
    struct hfsnode 		*hp = VTOH(ap->a_vp);
    struct hfsmount 	*hfsmp = VTOHFS(ap->a_vp);
    int					retval = E_NONE;
    daddr_t				logBlockSize;
    size_t				bytesContAvail = 0;
    struct proc			*p = NULL;
    int					lockExtBtree;

#define DEBUG_BMAP 0
#if DEBUG_BMAP
    DBG_FUNC_NAME("hfs_bmap");
    DBG_VOP_LOCKS_DECL(2);
    DBG_VOP_PRINT_FUNCNAME();
    DBG_VOP_PRINT_VNODE_INFO(ap->a_vp);

    DBG_VOP_LOCKS_INIT(0,ap->a_vp, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_POS);
    if (ap->a_vpp != NULL) {
        DBG_VOP_LOCKS_INIT(1,*ap->a_vpp, VOPDBG_IGNORE, VOPDBG_UNLOCKED, VOPDBG_IGNORE, VOPDBG_POS);
    } else {
        DBG_VOP_LOCKS_INIT(1,NULL, VOPDBG_IGNORE, VOPDBG_IGNORE, VOPDBG_IGNORE, VOPDBG_POS);
	};
#endif

	DBG_IO(("\tMapped blk %d --> ", ap->a_bn));
    /*
     * Check for underlying vnode requests and ensure that logical
     * to physical mapping is requested.
     */
    if (ap->a_vpp != NULL)
        *ap->a_vpp = VTOH(ap->a_vp)->h_meta->h_devvp;
    if (ap->a_bnp == NULL)
        return (0);

    lockExtBtree = hasOverflowExtents(hp);
    if (lockExtBtree)
    {
        p = current_proc();
        retval = hfs_metafilelocking(hfsmp, kHFSExtentsFileID, LK_EXCLUSIVE | LK_CANRECURSE, p);
        if (retval)
            return (retval);
    }

	logBlockSize = GetLogicalBlockSize(ap->a_vp);

	retval = MacToVFSError(
                               MapFileBlockC (HFSTOVCB(hfsmp),
                                              HTOFCB(hp),
                                              MAXPHYSIO,
                                              (off_t)(ap->a_bn * logBlockSize),
                                              ap->a_bnp,
                                              &bytesContAvail));

    if (lockExtBtree) (void) hfs_metafilelocking(hfsmp, kHFSExtentsFileID, LK_RELEASE, p);

    if (retval == E_NONE) {
        /* Figure out how many read ahead blocks there are */
        if (ap->a_runp != NULL) {
            if (can_cluster(logBlockSize)) {
                /* Make sure this result never goes negative: */
                *ap->a_runp = (bytesContAvail < logBlockSize) ? 0 : (bytesContAvail / logBlockSize) - 1;
            } else {
                *ap->a_runp = 0;
            };
        };
    };

    DBG_IO(("%d:%d.\n", *ap->a_bnp, (bytesContAvail < logBlockSize) ? 0 : (bytesContAvail / logBlockSize) - 1));

#if DEBUG_BMAP

    DBG_VOP_LOCKS_TEST(retval);
#endif

    if (ap->a_runp) {
        DBG_ASSERT((*ap->a_runp * logBlockSize) < bytesContAvail);							/* At least *ap->a_runp blocks left and ... */
        if (can_cluster(logBlockSize)) {
            DBG_ASSERT(bytesContAvail - (*ap->a_runp * logBlockSize) < (2*logBlockSize));	/* ... at most 1 logical block accounted for by current block */
                                                                                            /* ... plus some sub-logical block sized piece */
        };
    };

    return (retval);
}

/* blktooff converts logical block number to file offset */

int
hfs_blktooff(ap)
struct vop_blktooff_args /* {
    struct vnode *a_vp;
    daddr_t a_lblkno;  
    off_t *a_offset;
} */ *ap;
{	
	if (ap->a_vp == NULL)
		return (EINVAL);
	*ap->a_offset = (off_t)ap->a_lblkno * PAGE_SIZE_64;

	return(0);
}

int
hfs_offtoblk(ap)
struct vop_offtoblk_args /* {
	struct vnode *a_vp;
	off_t a_offset;    
	daddr_t *a_lblkno;
} */ *ap;
{	
	long lbsize, boff;

	if (ap->a_vp == NULL)
		return (EINVAL);
	*ap->a_lblkno = ap->a_offset / PAGE_SIZE_64;

	return(0);
}

int
hfs_cmap(ap)
struct vop_cmap_args /* {
	struct vnode *a_vp;
	off_t a_foffset;    
	size_t a_size;
	daddr_t *a_bpn;
	size_t *a_run;
	void *a_poff;
} */ *ap;
{
    struct hfsnode 	*hp = VTOH(ap->a_vp);
    struct hfsmount 	*hfsmp = VTOHFS(ap->a_vp);
    size_t				bytesContAvail = 0;
    int			retval = E_NONE;
    int					lockExtBtree;
    struct proc		*p = NULL;

#define DEBUG_CMAP 0
#if DEBUG_CMAP
    DBG_FUNC_NAME("hfs_cmap");
    DBG_VOP_LOCKS_DECL(2);
    DBG_VOP_PRINT_FUNCNAME();
    DBG_VOP_PRINT_VNODE_INFO(ap->a_vp);

    DBG_VOP_LOCKS_INIT(0, ap->a_vp, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_POS);
#endif

    DBG_IO(("\tMapped offset %qx --> ", ap->a_foffset));
    /*
     * Check for underlying vnode requests and ensure that logical
     * to physical mapping is requested.
     */
    if (ap->a_bpn == NULL)
        return (0);

    if (lockExtBtree = hasOverflowExtents(hp))
    {
        p = current_proc();
        if (retval = hfs_metafilelocking(hfsmp, kHFSExtentsFileID, LK_EXCLUSIVE | LK_CANRECURSE, p))
            return (retval);
    }
    retval = MacToVFSError(
			   MapFileBlockC (HFSTOVCB(hfsmp),
					  HTOFCB(hp),
					  ap->a_size,
					  ap->a_foffset,
					  ap->a_bpn,
					  &bytesContAvail));

    if (lockExtBtree) (void) hfs_metafilelocking(hfsmp, kHFSExtentsFileID, LK_RELEASE, p);

    if ((retval == E_NONE) && (ap->a_run))
		*ap->a_run = bytesContAvail;

    if (ap->a_poff)
		*(int *)ap->a_poff = 0;

    DBG_IO(("%d:%d.\n", *ap->a_bpn, bytesContAvail));

#if DEBUG_BMAP

    DBG_VOP_LOCKS_TEST(retval);
#endif

    return (retval);

}

/*
 * Calculate the logical to physical mapping if not done already,
 * then call the device strategy routine.
#
#vop_strategy {
#	IN struct buf *bp;
    */
int
hfs_strategy(ap)
struct vop_strategy_args /* {
    struct buf *a_bp;
} */ *ap;
{
    register struct buf *bp = ap->a_bp;
    register struct vnode *vp = bp->b_vp;
    register struct hfsnode *hp;
    int retval = 0;

	DBG_FUNC_NAME("hfs_strategy");

//	DBG_VOP_PRINT_FUNCNAME();DBG_VOP_CONT(("\n"));

    hp = VTOH(vp);

    if ( !(bp->b_flags & B_VECTORLIST)) {

        if (vp->v_type == VBLK || vp->v_type == VCHR)
	    panic("hfs_strategy: device vnode passed!");

	if (bp->b_flags & B_PAGELIST) {
	    /*
	     * if we have a page list associated with this bp,
	     * then go through cluste_bp since it knows how to 
	     * deal with a page request that might span non-contiguous
	     * physical blocks on the disk...
	     */
	    retval = cluster_bp(bp);
	    vp = hp->h_meta->h_devvp;
	    bp->b_dev = vp->v_rdev;

	    return (retval);
	}
	/*
	 * If we don't already know the filesystem relative block number
	 * then get it using VOP_BMAP().  If VOP_BMAP() returns the block
	 * number as -1 then we've got a hole in the file.  HFS filesystems
	 * don't allow files with holes, so we shouldn't ever see this.
	 */
	if (bp->b_blkno == bp->b_lblkno) {
	    if ((retval = VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL))) {
	        bp->b_error = retval;
		bp->b_flags |= B_ERROR;
		biodone(bp);
		return (retval);
	    }
	    if ((long)bp->b_blkno == -1)
	        clrbuf(bp);
	}
	if ((long)bp->b_blkno == -1) {
	    biodone(bp);
	    return (0);
	}
	if (bp->b_validend == 0) {
	    /* Record the exact size of the I/O transfer about to be made: */
	    DBG_ASSERT(bp->b_validoff == 0);
	    bp->b_validend = bp->b_bcount;
	    DBG_ASSERT(bp->b_dirtyoff == 0);
	};
    }
    vp = hp->h_meta->h_devvp;
    bp->b_dev = vp->v_rdev;
    DBG_IO(("\t\t>>>%s: continuing w/ vp: 0x%x with logBlk Ox%X and phyBlk Ox%X\n", funcname, (u_int)vp, bp->b_lblkno, bp->b_blkno));

    return VOCALL (vp->v_op, VOFFSET(vop_strategy), ap);
}


/*
#% reallocblks	vp	L L L
#
 vop_reallocblks {
     IN struct vnode *vp;
     IN struct cluster_save *buflist;

     */

int
hfs_reallocblks(ap)
struct vop_reallocblks_args /* {
    struct vnode *a_vp;
    struct cluster_save *a_buflist;
} */ *ap;
{
    DBG_FUNC_NAME("hfs_reallocblks");
    DBG_VOP_LOCKS_DECL(1);
    DBG_VOP_PRINT_FUNCNAME();
    DBG_VOP_PRINT_VNODE_INFO(ap->a_vp);DBG_VOP_CONT(("\n"));

    DBG_VOP_LOCKS_INIT(0,ap->a_vp, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_POS);

    /* Currently no support for clustering */		/* XXX */
    DBG_VOP_LOCKS_TEST(ENOSPC);
    return (ENOSPC);
}



/*
#
#% truncate	vp	L L L
#
vop_truncate {
    IN struct vnode *vp;
    IN off_t length;
    IN int flags;	(IO_SYNC)
    IN struct ucred *cred;
    IN struct proc *p;
};
 * Truncate the hfsnode hp to at most length size, freeing (or adding) the
 * disk blocks.
 */
int hfs_truncate(ap)
    struct vop_truncate_args /* {
        struct vnode *a_vp;
        off_t a_length;
        int a_flags;
        struct ucred *a_cred;
        struct proc *a_p;
    } */ *ap;
{
    register struct vnode *vp = ap->a_vp;
    register struct hfsnode *hp = VTOH(vp);
    off_t length = ap->a_length;
    long vflags;
    struct timeval tv;
    int retval;
    FCB *fcb;
    off_t bytesToAdd;
    off_t actualBytesAdded;
    DBG_FUNC_NAME("hfs_truncate");
    DBG_VOP_LOCKS_DECL(1);
    DBG_VOP_PRINT_FUNCNAME();
    DBG_VOP_PRINT_VNODE_INFO(ap->a_vp);DBG_VOP_CONT(("\n"));
    DBG_VOP_LOCKS_INIT(0,ap->a_vp, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_POS);

#if HFS_DIAGNOSTIC
    debug_check_blocksizes(ap->a_vp);
#endif

    fcb = HTOFCB(hp);

    KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 7)) | DBG_FUNC_START,
		 (int)length, fcb->fcbEOF, fcb->fcbPLen, 0, 0);

    if (length < 0) {
        DBG_VOP_LOCKS_TEST(EINVAL);
        return (EINVAL);
    }

    if ((!ISHFSPLUS(VTOVCB(vp))) && (length > (off_t)MAXHFSFILESIZE)) {	
        DBG_VOP_LOCKS_TEST(EFBIG);
	return (EFBIG);
    }

    if (vp->v_type != VREG && vp->v_type != VLNK) {		
        DBG_VOP_LOCKS_TEST(EISDIR);
        return (EISDIR);		/* hfs doesn't support truncating of directories */
    }

    tv = time;
    retval = E_NONE;
	
    DBG_RW(("%s: truncate from Ox%lX to Ox%X bytes\n", funcname, fcb->fcbPLen, length));

    /* 
     * we cannot just check if fcb->fcbEOF == length (as an optimization)
     * since there may be extra physical blocks that also need truncation
     */

    if (fcb->fcbEOF > fcb->fcbMaxEOF)
        fcb->fcbMaxEOF = fcb->fcbEOF;

    /*
     * Lengthen the size of the file. We must ensure that the
     * last byte of the file is allocated. Since the smallest
     * value of fcbEOF is 0, length will be at least 1.
     */
    if (length > fcb->fcbEOF) {
        off_t filePosition;
	daddr_t logBlockNo;
	long logBlockSize;
	long blkOffset;
	off_t bytestoclear;
	int blockZeroCount;
	struct buf *bp=NULL;

	/*
	 * If we don't have enough physical space then
	 * we need to extend the physical size.
	 */
	if (length > fcb->fcbPLen) {
	    /* lock extents b-tree (also protects volume bitmap) */
	    retval = hfs_metafilelocking(HTOHFS(hp), kHFSExtentsFileID, LK_EXCLUSIVE, ap->a_p);
	    if (retval)
	        goto Err_Exit;

	    while ((length > fcb->fcbPLen) && (retval == E_NONE)) {
	        bytesToAdd = length - fcb->fcbPLen;
		retval = MacToVFSError(
                                       ExtendFileC (HTOVCB(hp),
                                                    fcb,
                                                    bytesToAdd,
                                                    kEFAllMask,	/* allocate all requested bytes or none */
                                                    &actualBytesAdded));

		if (actualBytesAdded == 0 && retval == E_NONE) {
		    if (length > fcb->fcbPLen)
		        length = fcb->fcbPLen;
		    break;
		}
	    } 
	    (void) hfs_metafilelocking(HTOHFS(hp), kHFSExtentsFileID, LK_RELEASE, ap->a_p);
	    if (retval)
	        goto Err_Exit;

	    DBG_ASSERT(length <= fcb->fcbPLen);
	    KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 7)) | DBG_FUNC_NONE,
			 (int)length, fcb->fcbEOF, fcb->fcbPLen, 0, 0);
	}
 
	if (! (ap->a_flags & IO_NOZEROFILL)) {

	    if (UBCISVALID(vp) && retval == E_NONE) {
	        u_long    devBlockSize;

		if (length > fcb->fcbMaxEOF) {

		    VOP_DEVBLOCKSIZE(hp->h_meta->h_devvp, &devBlockSize);
		
		    retval = cluster_write(vp, (struct uio *) 0, fcb->fcbEOF, length, fcb->fcbMaxEOF,
					   (off_t)0, devBlockSize, ((ap->a_flags & IO_SYNC) | IO_HEADZEROFILL));

		    if (retval)
		        goto Err_Exit;
		}
	    } else {

	    /*
	     * zero out any new logical space...
	     */
	    bytestoclear = length - fcb->fcbEOF;
	    filePosition = fcb->fcbEOF;

	    while (bytestoclear > 0) {
	        logBlockNo   = (daddr_t)(filePosition / PAGE_SIZE_64);
		blkOffset    = (long)(filePosition & PAGE_MASK_64);  

		if (((off_t)(fcb->fcbPLen) - ((off_t)logBlockNo * (off_t)PAGE_SIZE)) < PAGE_SIZE_64)
		    logBlockSize = (off_t)(fcb->fcbPLen) - ((off_t)logBlockNo * PAGE_SIZE_64);
		else
		    logBlockSize = PAGE_SIZE;
		
		if (logBlockSize < blkOffset)
		    panic("hfs_truncate: bad logBlockSize computed\n");
		        
		blockZeroCount = MIN(bytestoclear, logBlockSize - blkOffset);

		if (blkOffset == 0 && ((bytestoclear >= logBlockSize) || filePosition >= fcb->fcbEOF)) {
		    bp = getblk(vp, logBlockNo, logBlockSize, 0, 0, BLK_WRITE);
		    retval = 0;

		} else {
		    retval = bread(vp, logBlockNo, logBlockSize, ap->a_cred, &bp);
		    if (retval) {
		        brelse(bp);
			goto Err_Exit;
		    }
		}
		bzero((char *)bp->b_data + blkOffset, blockZeroCount);
				
		bp->b_flags |= B_DIRTY | B_AGE;

		if (ap->a_flags & IO_SYNC)
		    VOP_BWRITE(bp);
		else if (logBlockNo % 32)
		    bawrite(bp);
		else
		    VOP_BWRITE(bp);	/* wait after we issue 32 requests */

		bytestoclear -= blockZeroCount;
		filePosition += blockZeroCount;
	    }
	    };
	}
	fcb->fcbEOF = length;

	if (fcb->fcbEOF > fcb->fcbMaxEOF)
	        fcb->fcbMaxEOF = fcb->fcbEOF;

	if (UBCISVALID(vp))
	        ubc_setsize(vp, (off_t)fcb->fcbEOF); /* XXX check errors */

    } else { /* Shorten the size of the file */

        if (fcb->fcbEOF > length) {
	    /*
	     * Any buffers that are past the truncation point need to be
	     * invalidated (to maintain buffer cache consistency).  For
	     * simplicity, we invalidate all the buffers by calling vinvalbuf.
	     */
	    if (UBCISVALID(vp))
	        ubc_setsize(vp, (off_t)length); /* XXX check errors */

	    vflags = ((length > 0) ? V_SAVE : 0)  | V_SAVEMETA;	
	    retval = vinvalbuf(vp, vflags, ap->a_cred, ap->a_p, 0, 0);
	}

	/*
	 * For a TBE process the deallocation of the file blocks is
	 * delayed until the file is closed.  And hfs_close calls
	 * truncate with the IO_NDELAY flag set.  So when IO_NDELAY
	 * isn't set, we make sure this isn't a TBE process.
	 */
	if ((ap->a_flags & IO_NDELAY) || (!ISSET(ap->a_p->p_flag, P_TBE))) {

	    /* lock extents b-tree (also protects volume bitmap) */
	    retval = hfs_metafilelocking(HTOHFS(hp), kHFSExtentsFileID, LK_EXCLUSIVE, ap->a_p);
	    if (retval)
	        goto Err_Exit;
	    retval = MacToVFSError(
                               TruncateFileC(	
                                             HTOVCB(hp),
                                             fcb,
                                             length,
                                             false));
	    (void) hfs_metafilelocking(HTOHFS(hp), kHFSExtentsFileID, LK_RELEASE, ap->a_p);
	    if (retval)
	        goto Err_Exit;

	    fcb->fcbMaxEOF = length;
	}
	fcb->fcbEOF = length;

	if (fcb->fcbFlags & fcbModifiedMask)
	    hp->h_nodeflags |= IN_MODIFIED;
    }
    hp->h_nodeflags |= IN_CHANGE | IN_UPDATE;
    retval = VOP_UPDATE(vp, &tv, &tv, MNT_WAIT);
    if (retval) {
        DBG_ERR(("Could not update truncate"));

	KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 7)) | DBG_FUNC_NONE,
		     -1, -1, -1, retval, 0);
    }
Err_Exit:;

#if HFS_DIAGNOSTIC
    debug_check_blocksizes(ap->a_vp);
#endif

    KERNEL_DEBUG((FSDBG_CODE(DBG_FSRW, 7)) | DBG_FUNC_END,
		 (int)length, fcb->fcbEOF, fcb->fcbPLen, retval, 0);

    DBG_VOP_LOCKS_TEST(retval);
    return (retval);
}



/*
#
#% allocate	vp	L L L
#
vop_allocate {
    IN struct vnode *vp;
    IN off_t length;
    IN int flags;
    IN struct ucred *cred;
    IN struct proc *p;
};
 * allocate the hfsnode hp to at most length size
 */
int hfs_allocate(ap)
    struct vop_allocate_args /* {
        struct vnode *a_vp;
        off_t a_length;
        u_int32_t  a_flags;
	off_t *a_bytesallocated;
        struct ucred *a_cred;
        struct proc *a_p;
    } */ *ap;
{
    register struct vnode *vp = ap->a_vp;
    register struct hfsnode *hp = VTOH(vp);
    off_t	length = ap->a_length;
    off_t	startingPEOF;
    off_t	moreBytesRequested;
    off_t	actualBytesAdded;
    long vflags;
    struct timeval tv;
    int retval, retval2;
    FCB *fcb;
    UInt32 extendFlags =0;   /* For call to ExtendFileC */
    DBG_FUNC_NAME("hfs_allocate");
    DBG_VOP_LOCKS_DECL(1);
    DBG_VOP_PRINT_FUNCNAME();
    DBG_VOP_PRINT_VNODE_INFO(ap->a_vp);DBG_VOP_CONT(("\n"));
    DBG_VOP_LOCKS_INIT(0,ap->a_vp, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_POS);

    /* Set the number of bytes allocated to 0 so that the caller will know that we
       did nothing.  ExtendFileC will fill this in for us if we actually allocate space */

    *(ap->a_bytesallocated) = 0; 

    /* Now for some error checking */

    if (length < (off_t)0) {
        DBG_VOP_LOCKS_TEST(EINVAL);
        return (EINVAL);
    }

    if (vp->v_type != VREG && vp->v_type != VLNK) {
        DBG_VOP_LOCKS_TEST(EISDIR);
        return (EISDIR);        /* hfs doesn't support truncating of directories */
    }

    /* Fill in the flags word for the call to Extend the file */

	if (ap->a_flags & ALLOCATECONTIG) {
		extendFlags |= kEFContigMask;
	}

    if (ap->a_flags & ALLOCATEALL) {
		extendFlags |= kEFAllMask;
	}

    fcb = HTOFCB(hp);
    tv = time;
    retval = E_NONE;
    startingPEOF = fcb->fcbPLen;

    if (ap->a_flags & ALLOCATEFROMPEOF) {
		length += fcb->fcbPLen;
	}

    DBG_RW(("%s: allocate from Ox%lX to Ox%X bytes\n", funcname, fcb->fcbPLen, (u_int)length));

    /* If no changes are necesary, then we're done */
    if (fcb->fcbPLen == length)
    	goto Std_Exit;

    /*
    * Lengthen the size of the file. We must ensure that the
    * last byte of the file is allocated. Since the smallest
    * value of fcbPLen is 0, length will be at least 1.
    */
    if (length > fcb->fcbPLen) {
		moreBytesRequested = length - fcb->fcbPLen;
		
		/* lock extents b-tree (also protects volume bitmap) */
		retval = hfs_metafilelocking(HTOHFS(hp), kHFSExtentsFileID, LK_EXCLUSIVE, ap->a_p);
		if (retval) goto Err_Exit;

		retval = MacToVFSError(
								ExtendFileC(HTOVCB(hp),
											fcb,
											moreBytesRequested,
											extendFlags,
											&actualBytesAdded));

		*(ap->a_bytesallocated) = actualBytesAdded;

		(void) hfs_metafilelocking(HTOHFS(hp), kHFSExtentsFileID, LK_RELEASE, ap->a_p);

		DBG_ASSERT(length <= fcb->fcbPLen);

		/*
		 * if we get an error and no changes were made then exit
		 * otherwise we must do the VOP_UPDATE to reflect the changes
		 */
        if (retval && (startingPEOF == fcb->fcbPLen)) goto Err_Exit;
        
        /*
         * Adjust actualBytesAdded to be allocation block aligned, not
         * clump size aligned.
         * NOTE: So what we are reporting does not affect reality
         * until the file is closed, when we truncate the file to allocation
         * block size.
         */

		if ((actualBytesAdded != 0) && (moreBytesRequested < actualBytesAdded)) {
			u_long					blks, blocksize;
			
			blocksize = VTOVCB(vp)->blockSize;
			blks = moreBytesRequested / blocksize;
			if ((blks * blocksize) != moreBytesRequested)
				blks++;
			
			*(ap->a_bytesallocated) = blks * blocksize;
		}

    } else { /* Shorten the size of the file */

    	if (fcb->fcbEOF > length) {
			/*
			 * Any buffers that are past the truncation point need to be
			 * invalidated (to maintain buffer cache consistency).  For
			 * simplicity, we invalidate all the buffers by calling vinvalbuf.
			 */
			vflags = ((length > 0) ? V_SAVE : 0) | V_SAVEMETA;
			(void) vinvalbuf(vp, vflags, ap->a_cred, ap->a_p, 0, 0);
		}

       /* lock extents b-tree (also protects volume bitmap) */
        retval = hfs_metafilelocking(HTOHFS(hp), kHFSExtentsFileID, LK_EXCLUSIVE, ap->a_p);
        if (retval) goto Err_Exit;

        retval = MacToVFSError(
                            TruncateFileC(
                                            HTOVCB(hp),
                                            fcb,
                                            length,
                                            false));
        (void) hfs_metafilelocking(HTOHFS(hp), kHFSExtentsFileID, LK_RELEASE, ap->a_p);

		/*
		 * if we get an error and no changes were made then exit
		 * otherwise we must do the VOP_UPDATE to reflect the changes
		 */
		if (retval && (startingPEOF == fcb->fcbPLen)) goto Err_Exit;
        if (fcb->fcbFlags & fcbModifiedMask)
           hp->h_nodeflags |= IN_MODIFIED;

        DBG_ASSERT(length <= fcb->fcbPLen)  // DEBUG DEBUG DEBUG DEBUG DEBUG DEBUG DEBUG

        if (fcb->fcbEOF > fcb->fcbPLen) {
			fcb->fcbEOF = fcb->fcbPLen;
			fcb->fcbMaxEOF = fcb->fcbPLen;

			if (UBCISVALID(vp))
				ubc_setsize(vp, (off_t)fcb->fcbEOF); /* XXX check errors */
        }
    }

Std_Exit:
    hp->h_nodeflags |= IN_CHANGE | IN_UPDATE;
	retval2 = VOP_UPDATE(vp, &tv, &tv, MNT_WAIT);

    if (retval == 0) retval = retval2;

Err_Exit:
    DBG_VOP_LOCKS_TEST(retval);
    return (retval);
}




/* pagein for HFS filesystem, similar to hfs_read(), but without cluster_read() */
int
hfs_pagein(ap)
	struct vop_pagein_args /* {
	   	struct vnode *a_vp,
	   	upl_t 	      a_pl,
		vm_offset_t   a_pl_offset,
		off_t         a_f_offset,
		size_t        a_size,
		struct ucred *a_cred,
		int           a_flags
	} */ *ap;
{
    register struct vnode *vp;
    struct hfsnode 	  *hp;
    FCB			  *fcb;
    long		   devBlockSize = 0;
    int 		   retval;

    DBG_FUNC_NAME("hfs_pagein");
    DBG_VOP_LOCKS_DECL(1);
    DBG_VOP_PRINT_FUNCNAME();
    DBG_VOP_PRINT_VNODE_INFO(vp);DBG_VOP_CONT(("\n"));
    DBG_VOP_LOCKS_INIT(0,vp, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_POS);

    vp  = ap->a_vp;
    hp  = VTOH(vp);
    fcb = HTOFCB(hp);

    if (vp->v_type != VREG && vp->v_type != VLNK)
	panic("hfs_pagein: vp not UBC type\n");

    DBG_VOP(("\tfile size Ox%X\n", (u_int)fcb->fcbEOF));
    DBG_VOP(("\tstarting at offset Ox%X of file, length Ox%X\n", (u_int)ap->a_f_offset, (u_int)ap->a_size));

#if HFS_DIAGNOSTIC
    debug_check_blocksizes(vp);
#endif

    VOP_DEVBLOCKSIZE(hp->h_meta->h_devvp, &devBlockSize);

    retval = cluster_pagein(vp, ap->a_pl, ap->a_pl_offset, ap->a_f_offset,
			 ap->a_size, (off_t)fcb->fcbEOF, devBlockSize,
			 ap->a_flags);

#if HFS_DIAGNOSTIC
    debug_check_blocksizes(vp);
#endif
    DBG_VOP_LOCKS_TEST(retval);

    return (retval);
}

/* 
 * pageout for HFS filesystem.
 */
int
hfs_pageout(ap)
	struct vop_pageout_args /* {
	   struct vnode *a_vp,
	   upl_t         a_pl,
	   vm_offset_t   a_pl_offset,
	   off_t         a_f_offset,
	   size_t        a_size,
	   struct ucred *a_cred,
	   int           a_flags
	} */ *ap;
{
	struct vnode	*vp = ap->a_vp;
	struct hfsnode	*hp =  VTOH(vp);
	FCB	        *fcb = HTOFCB(hp);
	int              retval;
	long             devBlockSize = 0;

	DBG_FUNC_NAME("hfs_pageout");
	DBG_VOP_LOCKS_DECL(1);
	DBG_VOP_PRINT_FUNCNAME();
	DBG_VOP_PRINT_VNODE_INFO(vp);DBG_VOP_CONT(("\n"));
	DBG_VOP(("\thfsnode 0x%x (%s)\n", (u_int)hp, H_NAME(hp)));
	DBG_VOP(("\tstarting at offset Ox%lX of file, length Ox%lX\n", 
		(UInt32)ap->a_f_offset, (UInt32)ap->a_size));

	DBG_VOP_LOCKS_INIT(0, vp, VOPDBG_LOCKED, 
		VOPDBG_LOCKED, VOPDBG_LOCKED, VOPDBG_POS);

#if HFS_DIAGNOSTIC
	debug_check_blocksizes(vp);
#endif

	if (UBCINVALID(vp))
		panic("hfs_pageout: Not a  VREG: vp=%x", vp);

	VOP_DEVBLOCKSIZE(hp->h_meta->h_devvp, &devBlockSize);

	retval = cluster_pageout(vp, ap->a_pl, ap->a_pl_offset, ap->a_f_offset, ap->a_size,
				 (off_t)fcb->fcbEOF, devBlockSize, ap->a_flags);
	/*
	 * If we successfully wrote any data, and we are not the superuser
	 * we clear the setuid and setgid bits as a precaution against
	 * tampering.
	 */
	if (retval == 0 && ap->a_cred && ap->a_cred->cr_uid != 0)
		hp->h_meta->h_mode &= ~(ISUID | ISGID);

#if HFS_DIAGNOSTIC
	debug_check_blocksizes(vp);
#endif

	DBG_VOP_LOCKS_TEST(retval);
	return (retval);
}

/*
 * Intercept B-Tree node writes to unswap them if necessary.
#
#vop_bwrite {
#	IN struct buf *bp;
 */
int
hfs_bwrite(ap)
struct vop_bwrite_args /* {
    struct buf *a_bp;
} */ *ap;
{
    register struct buf *bp = ap->a_bp;
    register struct vnode *vp = bp->b_vp;
    BlockDescriptor block;
    int retval = 0;

	DBG_FUNC_NAME("hfs_bwrite");

#if BYTE_ORDER == LITTLE_ENDIAN
    /* Trap B-Tree writes */
    if ((H_FILEID(VTOH(vp)) == kHFSExtentsFileID) ||
        (H_FILEID(VTOH(vp)) == kHFSCatalogFileID)) {

        /* Swap if the B-Tree node is in native byte order */
        if (((UInt16 *)((char *)bp->b_data + bp->b_bcount - 2))[0] == 0x000e) {
            /* Prepare the block pointer */
            block.blockHeader = bp;
            block.buffer = bp->b_data + IOBYTEOFFSETFORBLK(bp->b_blkno, VTOHFS(vp)->hfs_phys_block_size);
            block.blockReadFromDisk = (bp->b_flags & B_CACHE) == 0;	/* not found in cache ==> came from disk */
            block.blockSize = bp->b_bcount;
    
            /* Endian un-swap B-Tree node */
            SWAP_BT_NODE (&block, ISHFSPLUS (VTOVCB(vp)), H_FILEID(VTOH(vp)), 1);
        }

        /* We don't check to make sure that it's 0x0e00 because it could be all zeros */
    }
#endif

    retval = vn_bwrite (ap);

    return (retval);
}