xref: /onnv-gate/usr/src/uts/common/fs/pcfs/pc_node.c (revision 2720:a82b4631f707)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident	"%Z%%M%	%I%	%E% SMI"

#include <sys/param.h>
#include <sys/t_lock.h>
#include <sys/errno.h>
#include <sys/sysmacros.h>
#include <sys/buf.h>
#include <sys/systm.h>
#include <sys/vfs.h>
#include <sys/vnode.h>
#include <sys/kmem.h>
#include <sys/proc.h>
#include <sys/cred.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <vm/pvn.h>
#include <sys/fs/pc_label.h>
#include <sys/fs/pc_fs.h>
#include <sys/fs/pc_dir.h>
#include <sys/fs/pc_node.h>
#include <sys/dirent.h>
#include <sys/fdio.h>
#include <sys/file.h>
#include <sys/conf.h>

struct pchead pcfhead[NPCHASH];
struct pchead pcdhead[NPCHASH];

extern krwlock_t pcnodes_lock;

static int	pc_getentryblock(struct pcnode *, struct buf **);
static int	syncpcp(struct pcnode *, int);

/*
 * fake entry for root directory, since this does not have a parent
 * pointing to it.
 */
struct pcdir pcfs_rootdirentry = {
	"",
	"",
	PCA_DIR
};

void
pc_init(void)
{
	struct pchead *hdp, *hfp;
	int i;
	for (i = 0; i < NPCHASH; i++) {
		hdp = &pcdhead[i];
		hfp = &pcfhead[i];
		hdp->pch_forw =  (struct pcnode *)hdp;
		hdp->pch_back =  (struct pcnode *)hdp;
		hfp->pch_forw =  (struct pcnode *)hfp;
		hfp->pch_back =  (struct pcnode *)hfp;
	}
}

struct pcnode *
pc_getnode(
	struct pcfs *fsp,	/* filsystem for node */
	daddr_t blkno,		/* phys block no of dir entry */
	int offset,		/* offset of dir entry in block */
	struct pcdir *ep)	/* node dir entry */
{
	struct pcnode *pcp;
	struct pchead *hp;
	struct vnode *vp;
	pc_cluster32_t scluster;

	ASSERT(fsp->pcfs_flags & PCFS_LOCKED);
	if (ep == (struct pcdir *)0) {
		ep = &pcfs_rootdirentry;
		scluster = 0;
	} else {
		scluster = pc_getstartcluster(fsp, ep);
	}
	/*
	 * First look for active nodes.
	 * File nodes are identified by the location (blkno, offset) of
	 * its directory entry.
	 * Directory nodes are identified by the starting cluster number
	 * for the entries.
	 */
	if (ep->pcd_attr & PCA_DIR) {
		hp = &pcdhead[PCDHASH(fsp, scluster)];
		rw_enter(&pcnodes_lock, RW_READER);
		for (pcp = hp->pch_forw;
		    pcp != (struct pcnode *)hp; pcp = pcp->pc_forw) {
			if ((fsp == VFSTOPCFS(PCTOV(pcp)->v_vfsp)) &&
			    (scluster == pcp->pc_scluster)) {
				VN_HOLD(PCTOV(pcp));
				rw_exit(&pcnodes_lock);
				return (pcp);
			}
		}
		rw_exit(&pcnodes_lock);
	} else {
		hp = &pcfhead[PCFHASH(fsp, blkno, offset)];
		rw_enter(&pcnodes_lock, RW_READER);
		for (pcp = hp->pch_forw;
		    pcp != (struct pcnode *)hp; pcp = pcp->pc_forw) {
			if ((fsp == VFSTOPCFS(PCTOV(pcp)->v_vfsp)) &&
			    ((pcp->pc_flags & PC_INVAL) == 0) &&
			    (blkno == pcp->pc_eblkno) &&
			    (offset == pcp->pc_eoffset)) {
				VN_HOLD(PCTOV(pcp));
				rw_exit(&pcnodes_lock);
				return (pcp);
			}
		}
		rw_exit(&pcnodes_lock);
	}
	/*
	 * Cannot find node in active list. Allocate memory for a new node
	 * initialize it, and put it on the active list.
	 */
	pcp = kmem_alloc(sizeof (struct pcnode), KM_SLEEP);
	bzero(pcp, sizeof (struct pcnode));
	vp = vn_alloc(KM_SLEEP);
	pcp->pc_vn = vp;
	pcp->pc_entry = *ep;
	pcp->pc_eblkno = blkno;
	pcp->pc_eoffset = offset;
	pcp->pc_scluster = scluster;
	pcp->pc_lcluster = scluster;
	pcp->pc_lindex = 0;
	pcp->pc_flags = 0;
	if (ep->pcd_attr & PCA_DIR) {
		vn_setops(vp, pcfs_dvnodeops);
		vp->v_type = VDIR;
		if (scluster == 0) {
			vp->v_flag = VROOT;
			blkno = offset = 0;
			if (IS_FAT32(fsp)) {
				pcp->pc_size = pc_fileclsize(fsp,
				    fsp->pcfs_rdirstart) * fsp->pcfs_clsize;
			} else {
				pcp->pc_size =
				    fsp->pcfs_rdirsec * fsp->pcfs_secsize;
			}
		} else
			pcp->pc_size = pc_fileclsize(fsp, scluster) *
			    fsp->pcfs_clsize;
	} else {
		vn_setops(vp, pcfs_fvnodeops);
		vp->v_type = VREG;
		vp->v_flag = VNOSWAP;
		fsp->pcfs_frefs++;
		pcp->pc_size = ltohi(ep->pcd_size);
	}
	fsp->pcfs_nrefs++;
	VFS_HOLD(PCFSTOVFS(fsp));
	vp->v_data = (caddr_t)pcp;
	vp->v_vfsp = PCFSTOVFS(fsp);
	vn_exists(vp);
	rw_enter(&pcnodes_lock, RW_WRITER);
	insque(pcp, hp);
	rw_exit(&pcnodes_lock);
	return (pcp);
}

int
syncpcp(struct pcnode *pcp, int flags)
{
	int err;
	if (!vn_has_cached_data(PCTOV(pcp)))
		err = 0;
	else
		err = VOP_PUTPAGE(PCTOV(pcp), (offset_t)0, (uint_t)0,
		    flags, (struct cred *)0);

	return (err);
}

void
pc_rele(struct pcnode *pcp)
{
	struct pcfs *fsp;
	struct vnode *vp;
	int err;

	vp = PCTOV(pcp);
	PC_DPRINTF1(8, "pc_rele vp=0x%p\n", (void *)vp);

	fsp = VFSTOPCFS(vp->v_vfsp);
	ASSERT(fsp->pcfs_flags & PCFS_LOCKED);

	rw_enter(&pcnodes_lock, RW_WRITER);
	pcp->pc_flags |= PC_RELEHOLD;

retry:
	if (vp->v_type != VDIR && (pcp->pc_flags & PC_INVAL) == 0) {
		/*
		 * If the file was removed while active it may be safely
		 * truncated now.
		 */

		if (pcp->pc_entry.pcd_filename[0] == PCD_ERASED) {
			(void) pc_truncate(pcp, 0);
		} else if (pcp->pc_flags & PC_CHG) {
			(void) pc_nodeupdate(pcp);
		}
		err = syncpcp(pcp, B_INVAL);
		if (err) {
			(void) syncpcp(pcp, B_INVAL|B_FORCE);
		}
	}
	if (vn_has_cached_data(vp)) {
		/*
		 * pvn_vplist_dirty will abort all old pages
		 */
		(void) pvn_vplist_dirty(vp, (u_offset_t)0,
		    pcfs_putapage, B_INVAL, (struct cred *)NULL);
	}

	(void) pc_syncfat(fsp);
	mutex_enter(&vp->v_lock);
	if (vn_has_cached_data(vp)) {
		mutex_exit(&vp->v_lock);
		goto retry;
	}
	ASSERT(!vn_has_cached_data(vp));

	vp->v_count--;  /* release our hold from vn_rele */
	if (vp->v_count > 0) { /* Is this check still needed? */
		PC_DPRINTF1(3, "pc_rele: pcp=0x%p HELD AGAIN!\n", (void *)pcp);
		mutex_exit(&vp->v_lock);
		pcp->pc_flags &= ~PC_RELEHOLD;
		rw_exit(&pcnodes_lock);
		return;
	}

	remque(pcp);
	rw_exit(&pcnodes_lock);
	if ((vp->v_type == VREG) && !(pcp->pc_flags & PC_INVAL)) {
		fsp->pcfs_frefs--;
	}
	fsp->pcfs_nrefs--;
	VFS_RELE(vp->v_vfsp);

	if (fsp->pcfs_nrefs < 0) {
		panic("pc_rele: nrefs count");
	}
	if (fsp->pcfs_frefs < 0) {
		panic("pc_rele: frefs count");
	}

	mutex_exit(&vp->v_lock);
	vn_invalid(vp);
	vn_free(vp);
	kmem_free(pcp, sizeof (struct pcnode));
}

/*
 * Mark a pcnode as modified with the current time.
 */
void
pc_mark_mod(struct pcnode *pcp)
{
	timestruc_t now;

	if (PCTOV(pcp)->v_type == VREG) {
		gethrestime(&now);
		if (pc_tvtopct(&now, &pcp->pc_entry.pcd_mtime))
			PC_DPRINTF1(2, "pc_mark_mod failed timestamp "
			    "conversion, curtime = %lld\n",
			    (long long)now.tv_sec);
		pcp->pc_flags |= PC_CHG;
	}
}

/*
 * Mark a pcnode as accessed with the current time.
 */
void
pc_mark_acc(struct pcnode *pcp)
{
	struct pctime pt = { 0, 0 };
	timestruc_t now;

	if (PCTOV(pcp)->v_type == VREG) {
		gethrestime(&now);
		if (pc_tvtopct(&now, &pcp->pc_entry.pcd_mtime))
			PC_DPRINTF1(2, "pc_mark_acc failed timestamp "
			    "conversion, curtime = %lld\n",
			    (long long)now.tv_sec);
		pcp->pc_entry.pcd_ladate = pt.pct_date;
		pcp->pc_flags |= PC_CHG;
	}
}

/*
 * Truncate a file to a length.
 * Node must be locked.
 */
int
pc_truncate(struct pcnode *pcp, uint_t length)
{
	struct pcfs *fsp;
	struct vnode *vp;
	int error = 0;

	PC_DPRINTF3(4, "pc_truncate pcp=0x%p, len=%u, size=%u\n",
	    (void *)pcp, length, pcp->pc_size);
	vp = PCTOV(pcp);
	if (pcp->pc_flags & PC_INVAL)
		return (EIO);
	fsp = VFSTOPCFS(vp->v_vfsp);
	/*
	 * directories are always truncated to zero and are not marked
	 */
	if (vp->v_type == VDIR) {
		error = pc_bfree(pcp, 0);
		return (error);
	}
	/*
	 * If length is the same as the current size
	 * just mark the pcnode and return.
	 */
	if (length > pcp->pc_size) {
		daddr_t bno;
		uint_t llcn;

		/*
		 * We are extending a file.
		 * Extend it with _one_ call to pc_balloc (no holes)
		 * since we don't need to use the block number(s).
		 */
		if ((daddr_t)howmany((offset_t)pcp->pc_size, fsp->pcfs_clsize) <
		    (llcn = (daddr_t)howmany((offset_t)length,
				fsp->pcfs_clsize))) {
			error = pc_balloc(pcp, (daddr_t)(llcn - 1), 1, &bno);
		}
		if (error) {
			PC_DPRINTF1(2, "pc_truncate: error=%d\n", error);
			/*
			 * probably ran out disk space;
			 * determine current file size
			 */
			pcp->pc_size = fsp->pcfs_clsize *
			    pc_fileclsize(fsp, pcp->pc_scluster);
		} else
			pcp->pc_size = length;

	} else if (length < pcp->pc_size) {
		/*
		 * We are shrinking a file.
		 * Free blocks after the block that length points to.
		 */
		if (pc_blkoff(fsp, length) == 0) {
			/*
			 * Truncation to a block (cluster size) boundary only
			 * requires us to invalidate everything after the new
			 * end of the file.
			 */
			(void) pvn_vplist_dirty(PCTOV(pcp), (u_offset_t)length,
				pcfs_putapage, B_INVAL | B_TRUNC, CRED());
		} else {
			/*
			 * pvn_vpzero() cannot deal with more than MAXBSIZE
			 * chunks. Since the FAT clustersize can get larger
			 * than that, we'll zero from the new length to the
			 * end of the cluster for clustersizes smaller than
			 * MAXBSIZE - or the end of the MAXBSIZE block in
			 * case we've got a large clustersize.
			 */
			size_t nbytes =
			    roundup(length, MIN(fsp->pcfs_clsize, MAXBSIZE)) -
			    length;

			pvn_vpzero(PCTOV(pcp), (u_offset_t)length, nbytes);
			(void) pvn_vplist_dirty(PCTOV(pcp),
			    (u_offset_t)length + nbytes,
			    pcfs_putapage, B_INVAL | B_TRUNC, CRED());
		}
		error = pc_bfree(pcp,
		    (pc_cluster32_t)howmany((offset_t)length,
			    fsp->pcfs_clsize));
		pcp->pc_size = length;
	}
	pc_mark_mod(pcp);
	return (error);
}

/*
 * Get block for entry.
 */
static int
pc_getentryblock(struct pcnode *pcp, struct buf **bpp)
{
	struct pcfs *fsp;

	PC_DPRINTF0(7, "pc_getentryblock ");
	fsp = VFSTOPCFS(PCTOV(pcp)->v_vfsp);
	if (pcp->pc_eblkno >= fsp->pcfs_datastart ||
	    (pcp->pc_eblkno - fsp->pcfs_rdirstart) <
	    (fsp->pcfs_rdirsec & ~(fsp->pcfs_spcl - 1))) {
		*bpp = bread(fsp->pcfs_xdev,
		    pc_dbdaddr(fsp, pcp->pc_eblkno), fsp->pcfs_clsize);
	} else {
		*bpp = bread(fsp->pcfs_xdev,
		    pc_dbdaddr(fsp, pcp->pc_eblkno),
		    (int)(fsp->pcfs_datastart-pcp->pc_eblkno) *
		    fsp->pcfs_secsize);
	}
	if ((*bpp)->b_flags & B_ERROR) {
		PC_DPRINTF0(1, "pc_getentryblock: error ");
		brelse(*bpp);
		pc_mark_irrecov(fsp);
		return (EIO);
	}
	return (0);
}

/*
 * Sync all data associated with a file.
 * Flush all the blocks in the buffer cache out to disk, sync the FAT and
 * update the directory entry.
 */
int
pc_nodesync(struct pcnode *pcp)
{
	struct pcfs *fsp;
	int err;
	struct vnode *vp;

	PC_DPRINTF1(7, "pc_nodesync pcp=0x%p\n", (void *)pcp);
	vp = PCTOV(pcp);
	fsp = VFSTOPCFS(vp->v_vfsp);
	err = 0;
	if (pcp->pc_flags & PC_MOD) {
		/*
		 * Flush all data blocks from buffer cache and
		 * update the FAT which points to the data.
		 */
		if (err = syncpcp(pcp, 0)) { /* %% ?? how to handle error? */
			if (err == ENOMEM)
				return (err);
			else {
				pc_mark_irrecov(fsp);
				return (EIO);
			}
		}
		pcp->pc_flags &= ~PC_MOD;
	}
	/*
	 * update the directory entry
	 */
	if (pcp->pc_flags & PC_CHG)
		(void) pc_nodeupdate(pcp);
	return (err);
}

/*
 * Update the node's directory entry.
 */
int
pc_nodeupdate(struct pcnode *pcp)
{
	struct buf *bp;
	int error;
	struct vnode *vp;
	struct pcfs *fsp;

	vp = PCTOV(pcp);
	fsp = VFSTOPCFS(vp->v_vfsp);
	if (IS_FAT32(fsp) && (vp->v_flag & VROOT)) {
		/* no node to update */
		pcp->pc_flags &= ~(PC_CHG | PC_MOD | PC_ACC);
		return (0);
	}
	if (vp->v_flag & VROOT) {
		panic("pc_nodeupdate");
	}
	if (pcp->pc_flags & PC_INVAL)
		return (0);
	PC_DPRINTF3(7, "pc_nodeupdate pcp=0x%p, bn=%ld, off=%d\n", (void *)pcp,
	    pcp->pc_eblkno, pcp->pc_eoffset);

	if (error = pc_getentryblock(pcp, &bp)) {
		return (error);
	}
	if (vp->v_type == VREG) {
		if (pcp->pc_flags & PC_CHG)
			pcp->pc_entry.pcd_attr |= PCA_ARCH;
		pcp->pc_entry.pcd_size = htoli(pcp->pc_size);
	}
	pc_setstartcluster(fsp, &pcp->pc_entry, pcp->pc_scluster);
	*((struct pcdir *)(bp->b_un.b_addr + pcp->pc_eoffset)) = pcp->pc_entry;
	bwrite2(bp);
	error = geterror(bp);
	if (error)
		error = EIO;
	brelse(bp);
	if (error) {
		PC_DPRINTF0(1, "pc_nodeupdate ERROR\n");
		pc_mark_irrecov(VFSTOPCFS(vp->v_vfsp));
	}
	pcp->pc_flags &= ~(PC_CHG | PC_MOD | PC_ACC);
	return (error);
}

/*
 * Verify that the disk in the drive is the same one that we
 * got the pcnode from.
 * MUST be called with node unlocked.
 */
/* ARGSUSED */
int
pc_verify(struct pcfs *fsp)
{
	int fdstatus = 0;
	int error = 0;

	if (!fsp || fsp->pcfs_flags & PCFS_IRRECOV)
		return (EIO);

	if (!(fsp->pcfs_flags & PCFS_NOCHK) && fsp->pcfs_fatp) {
		PC_DPRINTF1(4, "pc_verify fsp=0x%p\n", (void *)fsp);
		error = cdev_ioctl(fsp->pcfs_vfs->vfs_dev,
		    FDGETCHANGE, (intptr_t)&fdstatus, FNATIVE|FKIOCTL,
		    NULL, NULL);

		if (error) {
			if (error == ENOTTY || error == ENXIO) {
				error = 0;
			} else {
				PC_DPRINTF1(1,
				    "pc_verify: FDGETCHANGE ioctl failed: %d\n",
				    error);
				pc_mark_irrecov(fsp);
			}
		} else if (fsp->pcfs_fatjustread) {
			/*
			 * Ignore the results of the ioctl if we just
			 * read the FAT.  There is a good chance that
			 * the disk changed bit will be on, because
			 * we've just mounted and we don't want to
			 * give a false positive that the sky is falling.
			 */
			fsp->pcfs_fatjustread = 0;
		} else {
			/*
			 * Oddly enough we can't check just one flag here. The
			 * x86 floppy driver sets a different flag
			 * (FDGC_DETECTED) than the sparc driver does.
			 * I think this MAY be a bug, and I filed 4165938
			 * to get someone to look at the behavior
			 * a bit more closely.  In the meantime, my testing and
			 * code examination seem to indicate it is safe to
			 * check for either bit being set.
			 */
			if (fdstatus & (FDGC_HISTORY | FDGC_DETECTED)) {
				PC_DPRINTF0(1, "pc_verify: change detected\n");
				pc_mark_irrecov(fsp);
			}
		}
	}
	if (!(error || fsp->pcfs_fatp)) {
		error = pc_getfat(fsp);
	}

	return (error);
}

/*
 * The disk has changed, pulling the rug out from beneath us.
 * Mark the FS as being in an irrecoverable state.
 * In a short while we'll clean up.
 */
void
pc_mark_irrecov(struct pcfs *fsp)
{
	if (!(fsp->pcfs_flags & PCFS_NOCHK)) {
		if (pc_lockfs(fsp, 1, 0)) {
			/*
			 * Locking failed, which currently would
			 * only happen if the FS were already
			 * marked as hosed.  If another reason for
			 * failure were to arise in the future, this
			 * routine would have to change.
			 */
			return;
		}

		fsp->pcfs_flags |= PCFS_IRRECOV;
		cmn_err(CE_WARN,
			"Disk was changed during an update or\n"
			"an irrecoverable error was encountered.\n"
			"File damage is possible.  To prevent further\n"
			"damage, this pcfs instance will now be frozen.\n"
			"Use umount(1M) to release the instance.\n");
		(void) pc_unlockfs(fsp);
	}
}

/*
 * The disk has been changed!
 */
void
pc_diskchanged(struct pcfs *fsp)
{
	struct pcnode	*pcp, *npcp = NULL;
	struct pchead	*hp;
	struct vnode	*vp;
	extern vfs_t	EIO_vfs;
	struct vfs	*vfsp;

	/*
	 * Eliminate all pcnodes (dir & file) associated with this fs.
	 * If the node is internal, ie, no references outside of
	 * pcfs itself, then release the associated vnode structure.
	 * Invalidate the in core FAT.
	 * Invalidate cached data blocks and blocks waiting for I/O.
	 */
	PC_DPRINTF1(1, "pc_diskchanged fsp=0x%p\n", (void *)fsp);

	vfsp = PCFSTOVFS(fsp);

	for (hp = pcdhead; hp < &pcdhead[NPCHASH]; hp++) {
		for (pcp = hp->pch_forw;
		    pcp != (struct pcnode *)hp; pcp = npcp) {
			npcp = pcp -> pc_forw;
			vp = PCTOV(pcp);
			if ((vp->v_vfsp == vfsp) &&
			    !(pcp->pc_flags & PC_RELEHOLD)) {
				mutex_enter(&(vp)->v_lock);
				if (vp->v_count > 0) {
					mutex_exit(&(vp)->v_lock);
					continue;
				}
				mutex_exit(&(vp)->v_lock);
				VN_HOLD(vp);
				remque(pcp);
				vp->v_data = NULL;
				vp->v_vfsp = &EIO_vfs;
				vp->v_type = VBAD;
				VN_RELE(vp);
				if (!(pcp->pc_flags & PC_EXTERNAL)) {
					(void) pvn_vplist_dirty(vp,
					    (u_offset_t)0, pcfs_putapage,
					    B_INVAL | B_TRUNC,
					    (struct cred *)NULL);
					vn_free(vp);
				}
				kmem_free(pcp, sizeof (struct pcnode));
				fsp->pcfs_nrefs --;
				VFS_RELE(vfsp);
			}
		}
	}
	for (hp = pcfhead; fsp->pcfs_frefs && hp < &pcfhead[NPCHASH]; hp++) {
		for (pcp = hp->pch_forw; fsp->pcfs_frefs &&
		    pcp != (struct pcnode *)hp; pcp = npcp) {
			npcp = pcp -> pc_forw;
			vp = PCTOV(pcp);
			if ((vp->v_vfsp == vfsp) &&
			    !(pcp->pc_flags & PC_RELEHOLD)) {
				mutex_enter(&(vp)->v_lock);
				if (vp->v_count > 0) {
					mutex_exit(&(vp)->v_lock);
					continue;
				}
				mutex_exit(&(vp)->v_lock);
				VN_HOLD(vp);
				remque(pcp);
				vp->v_data = NULL;
				vp->v_vfsp = &EIO_vfs;
				vp->v_type = VBAD;
				VN_RELE(vp);
				if (!(pcp->pc_flags & PC_EXTERNAL)) {
					(void) pvn_vplist_dirty(vp,
					    (u_offset_t)0, pcfs_putapage,
					    B_INVAL | B_TRUNC,
					    (struct cred *)NULL);
					vn_free(vp);
				}
				kmem_free(pcp, sizeof (struct pcnode));
				fsp->pcfs_frefs --;
				fsp->pcfs_nrefs --;
				VFS_RELE(vfsp);
			}
		}
	}
#ifdef undef
	if (fsp->pcfs_frefs) {
		rw_exit(&pcnodes_lock);
		panic("pc_diskchanged: frefs");
	}
	if (fsp->pcfs_nrefs) {
		rw_exit(&pcnodes_lock);
		panic("pc_diskchanged: nrefs");
	}
#endif
	if (!(vfsp->vfs_flag & VFS_UNMOUNTED) &&
	    fsp->pcfs_fatp != (uchar_t *)0) {
		pc_invalfat(fsp);
	} else {
		binval(fsp->pcfs_xdev);
	}
}