vfs_subr.c

早期freebsd实现

/*
 * Copyright (c) 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)vfs_subr.c	8.13 (Berkeley) 4/18/94
 */

/*
 * External virtual filesystem routines
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/time.h>
#include <sys/vnode.h>
#include <sys/stat.h>
#include <sys/namei.h>
#include <sys/ucred.h>
#include <sys/buf.h>
#include <sys/errno.h>
#include <sys/malloc.h>
#include <sys/domain.h>
#include <sys/mbuf.h>

#include <vm/vm.h>
#include <sys/sysctl.h>

#include <miscfs/specfs/specdev.h>

enum vtype iftovt_tab[16] = {
	VNON, VFIFO, VCHR, VNON, VDIR, VNON, VBLK, VNON,
	VREG, VNON, VLNK, VNON, VSOCK, VNON, VNON, VBAD,
};
int	vttoif_tab[9] = {
	0, S_IFREG, S_IFDIR, S_IFBLK, S_IFCHR, S_IFLNK,
	S_IFSOCK, S_IFIFO, S_IFMT,
};

/*
 * Insq/Remq for the vnode usage lists.
 */
#define	bufinsvn(bp, dp)	LIST_INSERT_HEAD(dp, bp, b_vnbufs)
#define	bufremvn(bp) {  \
	LIST_REMOVE(bp, b_vnbufs); \
	(bp)->b_vnbufs.le_next = NOLIST; \
}

TAILQ_HEAD(freelst, vnode) vnode_free_list;	/* vnode free list */
struct mntlist mountlist;			/* mounted filesystem list */

/*
 * Initialize the vnode management data structures.
 */
vntblinit()
{

	TAILQ_INIT(&vnode_free_list);
	TAILQ_INIT(&mountlist);
}

/*
 * Lock a filesystem.
 * Used to prevent access to it while mounting and unmounting.
 */
vfs_lock(mp)
	register struct mount *mp;
{

	while(mp->mnt_flag & MNT_MLOCK) {
		mp->mnt_flag |= MNT_MWAIT;
		sleep((caddr_t)mp, PVFS);
	}
	mp->mnt_flag |= MNT_MLOCK;
	return (0);
}

/*
 * Unlock a locked filesystem.
 * Panic if filesystem is not locked.
 */
void
vfs_unlock(mp)
	register struct mount *mp;
{

	if ((mp->mnt_flag & MNT_MLOCK) == 0)
		panic("vfs_unlock: not locked");
	mp->mnt_flag &= ~MNT_MLOCK;
	if (mp->mnt_flag & MNT_MWAIT) {
		mp->mnt_flag &= ~MNT_MWAIT;
		wakeup((caddr_t)mp);
	}
}

/*
 * Mark a mount point as busy.
 * Used to synchronize access and to delay unmounting.
 */
vfs_busy(mp)
	register struct mount *mp;
{

	while(mp->mnt_flag & MNT_MPBUSY) {
		mp->mnt_flag |= MNT_MPWANT;
		sleep((caddr_t)&mp->mnt_flag, PVFS);
	}
	if (mp->mnt_flag & MNT_UNMOUNT)
		return (1);
	mp->mnt_flag |= MNT_MPBUSY;
	return (0);
}

/*
 * Free a busy filesystem.
 * Panic if filesystem is not busy.
 */
vfs_unbusy(mp)
	register struct mount *mp;
{

	if ((mp->mnt_flag & MNT_MPBUSY) == 0)
		panic("vfs_unbusy: not busy");
	mp->mnt_flag &= ~MNT_MPBUSY;
	if (mp->mnt_flag & MNT_MPWANT) {
		mp->mnt_flag &= ~MNT_MPWANT;
		wakeup((caddr_t)&mp->mnt_flag);
	}
}

/*
 * Lookup a mount point by filesystem identifier.
 */
struct mount *
getvfs(fsid)
	fsid_t *fsid;
{
	register struct mount *mp;

	for (mp = mountlist.tqh_first; mp != NULL; mp = mp->mnt_list.tqe_next) {
		if (mp->mnt_stat.f_fsid.val[0] == fsid->val[0] &&
		    mp->mnt_stat.f_fsid.val[1] == fsid->val[1])
			return (mp);
	}
	return ((struct mount *)0);
}

/*
 * Get a new unique fsid
 */
void
getnewfsid(mp, mtype)
	struct mount *mp;
	int mtype;
{
static u_short xxxfs_mntid;

	fsid_t tfsid;

	mp->mnt_stat.f_fsid.val[0] = makedev(nblkdev + mtype, 0);
	mp->mnt_stat.f_fsid.val[1] = mtype;
	if (xxxfs_mntid == 0)
		++xxxfs_mntid;
	tfsid.val[0] = makedev(nblkdev + mtype, xxxfs_mntid);
	tfsid.val[1] = mtype;
	if (mountlist.tqh_first != NULL) {
		while (getvfs(&tfsid)) {
			tfsid.val[0]++;
			xxxfs_mntid++;
		}
	}
	mp->mnt_stat.f_fsid.val[0] = tfsid.val[0];
}

/*
 * Set vnode attributes to VNOVAL
 */
void vattr_null(vap)
	register struct vattr *vap;
{

	vap->va_type = VNON;
	vap->va_size = vap->va_bytes = VNOVAL;
	vap->va_mode = vap->va_nlink = vap->va_uid = vap->va_gid =
		vap->va_fsid = vap->va_fileid =
		vap->va_blocksize = vap->va_rdev =
		vap->va_atime.ts_sec = vap->va_atime.ts_nsec =
		vap->va_mtime.ts_sec = vap->va_mtime.ts_nsec =
		vap->va_ctime.ts_sec = vap->va_ctime.ts_nsec =
		vap->va_flags = vap->va_gen = VNOVAL;
	vap->va_vaflags = 0;
}

/*
 * Routines having to do with the management of the vnode table.
 */
extern int (**dead_vnodeop_p)();
extern void vclean();
long numvnodes;
extern struct vattr va_null;

/*
 * Return the next vnode from the free list.
 */
getnewvnode(tag, mp, vops, vpp)
	enum vtagtype tag;
	struct mount *mp;
	int (**vops)();
	struct vnode **vpp;
{
	register struct vnode *vp;
	int s;

	if ((vnode_free_list.tqh_first == NULL &&
	     numvnodes < 2 * desiredvnodes) ||
	    numvnodes < desiredvnodes) {
		vp = (struct vnode *)malloc((u_long)sizeof *vp,
		    M_VNODE, M_WAITOK);
		bzero((char *)vp, sizeof *vp);
		numvnodes++;
	} else {
		if ((vp = vnode_free_list.tqh_first) == NULL) {
			tablefull("vnode");
			*vpp = 0;
			return (ENFILE);
		}
		if (vp->v_usecount)
			panic("free vnode isn't");
		TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
		/* see comment on why 0xdeadb is set at end of vgone (below) */
		vp->v_freelist.tqe_prev = (struct vnode **)0xdeadb;
		vp->v_lease = NULL;
		if (vp->v_type != VBAD)
			vgone(vp);
#ifdef DIAGNOSTIC
		if (vp->v_data)
			panic("cleaned vnode isn't");
		s = splbio();
		if (vp->v_numoutput)
			panic("Clean vnode has pending I/O's");
		splx(s);
#endif
		vp->v_flag = 0;
		vp->v_lastr = 0;
		vp->v_ralen = 0;
		vp->v_maxra = 0;
		vp->v_lastw = 0;
		vp->v_lasta = 0;
		vp->v_cstart = 0;
		vp->v_clen = 0;
		vp->v_socket = 0;
	}
	vp->v_type = VNON;
	cache_purge(vp);
	vp->v_tag = tag;
	vp->v_op = vops;
	insmntque(vp, mp);
	*vpp = vp;
	vp->v_usecount = 1;
	vp->v_data = 0;
	return (0);
}

/*
 * Move a vnode from one mount queue to another.
 */
insmntque(vp, mp)
	register struct vnode *vp;
	register struct mount *mp;
{

	/*
	 * Delete from old mount point vnode list, if on one.
	 */
	if (vp->v_mount != NULL)
		LIST_REMOVE(vp, v_mntvnodes);
	/*
	 * Insert into list of vnodes for the new mount point, if available.
	 */
	if ((vp->v_mount = mp) == NULL)
		return;
	LIST_INSERT_HEAD(&mp->mnt_vnodelist, vp, v_mntvnodes);
}

/*
 * Update outstanding I/O count and do wakeup if requested.
 */
vwakeup(bp)
	register struct buf *bp;
{
	register struct vnode *vp;

	bp->b_flags &= ~B_WRITEINPROG;
	if (vp = bp->b_vp) {
		vp->v_numoutput--;
		if (vp->v_numoutput < 0)
			panic("vwakeup: neg numoutput");
		if ((vp->v_flag & VBWAIT) && vp->v_numoutput <= 0) {
			if (vp->v_numoutput < 0)
				panic("vwakeup: neg numoutput");
			vp->v_flag &= ~VBWAIT;
			wakeup((caddr_t)&vp->v_numoutput);
		}
	}
}

/*
 * Flush out and invalidate all buffers associated with a vnode.
 * Called with the underlying object locked.
 */
int
vinvalbuf(vp, flags, cred, p, slpflag, slptimeo)
	register struct vnode *vp;
	int flags;
	struct ucred *cred;
	struct proc *p;
	int slpflag, slptimeo;
{
	register struct buf *bp;
	struct buf *nbp, *blist;
	int s, error;

	if (flags & V_SAVE) {
		if (error = VOP_FSYNC(vp, cred, MNT_WAIT, p))
			return (error);
		if (vp->v_dirtyblkhd.lh_first != NULL)
			panic("vinvalbuf: dirty bufs");
	}
	for (;;) {
		if ((blist = vp->v_cleanblkhd.lh_first) && flags & V_SAVEMETA)
			while (blist && blist->b_lblkno < 0)
				blist = blist->b_vnbufs.le_next;
		if (!blist && (blist = vp->v_dirtyblkhd.lh_first) && 
		    (flags & V_SAVEMETA))
			while (blist && blist->b_lblkno < 0)
				blist = blist->b_vnbufs.le_next;
		if (!blist)
			break;

		for (bp = blist; bp; bp = nbp) {
			nbp = bp->b_vnbufs.le_next;
			if (flags & V_SAVEMETA && bp->b_lblkno < 0)
				continue;
			s = splbio();
			if (bp->b_flags & B_BUSY) {
				bp->b_flags |= B_WANTED;
				error = tsleep((caddr_t)bp,
					slpflag | (PRIBIO + 1), "vinvalbuf",
					slptimeo);
				splx(s);
				if (error)
					return (error);
				break;
			}
			bremfree(bp);
			bp->b_flags |= B_BUSY;
			splx(s);
			/*
			 * XXX Since there are no node locks for NFS, I believe
			 * there is a slight chance that a delayed write will
			 * occur while sleeping just above, so check for it.
			 */
			if ((bp->b_flags & B_DELWRI) && (flags & V_SAVE)) {
				(void) VOP_BWRITE(bp);
				break;
			}
			bp->b_flags |= B_INVAL;
			brelse(bp);
		}
	}
	if (!(flags & V_SAVEMETA) &&
	    (vp->v_dirtyblkhd.lh_first || vp->v_cleanblkhd.lh_first))
		panic("vinvalbuf: flush failed");
	return (0);
}

/*
 * Associate a buffer with a vnode.
 */
bgetvp(vp, bp)
	register struct vnode *vp;
	register struct buf *bp;
{

	if (bp->b_vp)
		panic("bgetvp: not free");
	VHOLD(vp);
	bp->b_vp = vp;
	if (vp->v_type == VBLK || vp->v_type == VCHR)
		bp->b_dev = vp->v_rdev;
	else
		bp->b_dev = NODEV;
	/*
	 * Insert onto list for new vnode.
	 */
	bufinsvn(bp, &vp->v_cleanblkhd);
}

/*
 * Disassociate a buffer from a vnode.
 */
brelvp(bp)
	register struct buf *bp;
{
	struct vnode *vp;

	if (bp->b_vp == (struct vnode *) 0)