/*
 * Copyright (c) 1982, 1986, 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. 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_vnops.c	8.2 (Berkeley) 1/21/94
 * $FreeBSD: src/sys/kern/vfs_vnops.c,v 1.87.2.13 2002/12/29 18:19:53 dillon Exp $
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/file2.h>
#include <sys/stat.h>
#include <sys/proc.h>
#include <sys/caps.h>
#include <sys/mount.h>
#include <sys/nlookup.h>
#include <sys/vnode.h>
#include <sys/buf.h>
#include <sys/filio.h>
#include <sys/ttycom.h>
#include <sys/conf.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/spinlock.h>
#include <sys/spinlock2.h>
#include <sys/unistd.h>

#include <sys/mplock2.h>

#include <vm/vm_object.h>

#include <machine/limits.h>

static int vn_closefile (struct file *fp);
static int vn_ioctl (struct file *fp, u_long com, caddr_t data,
		struct ucred *cred, struct sysmsg *msg);
static int vn_read (struct file *fp, struct uio *uio,
		struct ucred *cred, int flags);
static int vn_kqfilter (struct file *fp, struct knote *kn);
static int vn_statfile (struct file *fp, struct stat *sb, struct ucred *cred);
static int vn_write (struct file *fp, struct uio *uio,
		struct ucred *cred, int flags);
static int vn_seek (struct file *fp, off_t offset, int whence, off_t *res);

struct fileops vnode_fileops = {
	.fo_read = vn_read,
	.fo_write = vn_write,
	.fo_ioctl = vn_ioctl,
	.fo_kqfilter = vn_kqfilter,
	.fo_stat = vn_statfile,
	.fo_close = vn_closefile,
	.fo_shutdown = nofo_shutdown,
	.fo_seek = vn_seek
};

/*
 * Common code for vnode open operations.  Check permissions, and call
 * the VOP_NOPEN or VOP_NCREATE routine.
 *
 * The caller is responsible for setting up nd with nlookup_init() and
 * for cleaning it up with nlookup_done(), whether we return an error
 * or not.
 *
 * On success nd->nl_open_vp will hold a referenced and, if requested,
 * locked vnode.  A locked vnode is requested via NLC_LOCKVP.  If fp
 * is non-NULL the vnode will be installed in the file pointer.
 *
 * NOTE: If the caller wishes the namecache entry to be operated with
 *	 a shared lock it must use NLC_SHAREDLOCK.  If NLC_LOCKVP is set
 *	 then the vnode lock will also be shared.
 *
 * NOTE: The vnode is referenced just once on return whether or not it
 *	 is also installed in the file pointer.
 */
int
vn_open(struct nlookupdata *nd, struct file **fpp, int fmode, int cmode)
{
	struct file *fp = fpp ? *fpp : NULL;
	struct vnode *vp;
	struct ucred *cred = nd->nl_cred;
	struct vattr vat;
	struct vattr *vap = &vat;
	int error;
	int vpexcl;
	u_int flags;
	uint64_t osize;
	struct mount *mp;

	/*
	 * Certain combinations are illegal
	 */
	if ((fmode & (FWRITE | O_TRUNC)) == O_TRUNC)
		return(EACCES);

	/*
	 * Lookup the path and create or obtain the vnode.  After a
	 * successful lookup a locked nd->nl_nch will be returned.
	 *
	 * The result of this section should be a locked vnode.
	 *
	 * XXX with only a little work we should be able to avoid locking
	 * the vnode if FWRITE, O_CREAT, and O_TRUNC are *not* set.
	 */
	nd->nl_flags |= NLC_OPEN;
	if (fmode & O_APPEND)
		nd->nl_flags |= NLC_APPEND;
	if (fmode & O_TRUNC)
		nd->nl_flags |= NLC_TRUNCATE;
	if (fmode & FREAD)
		nd->nl_flags |= NLC_READ;
	if (fmode & FWRITE)
		nd->nl_flags |= NLC_WRITE;
	if ((fmode & O_EXCL) == 0 && (fmode & O_NOFOLLOW) == 0)
		nd->nl_flags |= NLC_FOLLOW;

	if (fmode & O_CREAT) {
		/*
		 * CONDITIONAL CREATE FILE CASE
		 *
		 * Setting NLC_CREATE causes a negative hit to store
		 * the negative hit ncp and not return an error.  Then
		 * nc_error or nc_vp may be checked to see if the ncp
		 * represents a negative hit.  NLC_CREATE also requires
		 * write permission on the governing directory or EPERM
		 * is returned.
		 *
		 * If the file exists but is missing write permission,
		 * nlookup() returns EACCES. This has to be handled specially
		 * when combined with O_EXCL.
		 */
		nd->nl_flags |= NLC_CREATE;
		nd->nl_flags |= NLC_REFDVP;
		bwillinode(1);
		error = nlookup(nd);
		if (error == EACCES && nd->nl_nch.ncp->nc_vp != NULL &&
		    (fmode & O_EXCL) && !nd->nl_dir_error)
		{
			error = EEXIST;
		}

		/*
		 * If no error and nd->nl_dvp is NULL, the nlookup represents
		 * a mount-point or cross-mount situation.  e.g.
		 * open("/var/cache", O_CREAT), where /var/cache is a
		 * mount point or a null-mount point.
		 */
		if (error == 0 && nd->nl_dvp == NULL)
			error = EINVAL;
	} else {
		/*
		 * NORMAL OPEN FILE CASE
		 */
		error = nlookup(nd);
	}

	if (error)
		return (error);

	/*
	 * split case to allow us to re-resolve and retry the ncp in case
	 * we get ESTALE.
	 *
	 * (error is 0 on entry / retry)
	 */
again:
	/*
	 * Checks for (likely) filesystem-modifying cases and allows
	 * the filesystem to stall the front-end.
	 */
	if ((fmode & (FWRITE | O_TRUNC)) ||
	    ((fmode & O_CREAT) && nd->nl_nch.ncp->nc_vp == NULL)) {
		error = ncp_writechk(&nd->nl_nch);
		if (error)
			return error;
	}

	vpexcl = 1;
	if (fmode & O_CREAT) {
		if (nd->nl_nch.ncp->nc_vp == NULL) {
			VATTR_NULL(vap);
			vap->va_type = VREG;
			vap->va_mode = cmode;
			vap->va_fuseflags = fmode; /* FUSE */
			if (fmode & O_EXCL)
				vap->va_vaflags |= VA_EXCLUSIVE;
			error = VOP_NCREATE(&nd->nl_nch, nd->nl_dvp, &vp,
					    nd->nl_cred, vap);
			if (error)
				return (error);
			fmode &= ~O_TRUNC;
			/* locked vnode is returned */
		} else {
			if (fmode & O_EXCL) {
				error = EEXIST;
			} else {
				error = cache_vget(&nd->nl_nch, cred,
						    LK_EXCLUSIVE, &vp);
			}
			if (error)
				return (error);
			fmode &= ~O_CREAT;
		}
	} else {
		/*
		 * In most other cases a shared lock on the vnode is
		 * sufficient.  However, the O_RDWR case needs an
		 * exclusive lock if the vnode is executable.  The
		 * NLC_EXCLLOCK_IFEXEC and NCF_NOTX flags help resolve
		 * this.
		 *
		 * NOTE: If NCF_NOTX is not set, we do not know the
		 *	 the state of the 'x' bits and have to get
		 *	 an exclusive lock for the EXCLLOCK_IFEXEC case.
		 */
		if ((nd->nl_flags & NLC_SHAREDLOCK) &&
		    ((nd->nl_flags & NLC_EXCLLOCK_IFEXEC) == 0 ||
		     nd->nl_nch.ncp->nc_flag & NCF_NOTX)) {
			error = cache_vget(&nd->nl_nch, cred, LK_SHARED, &vp);
			vpexcl = 0;
		} else {
			error = cache_vget(&nd->nl_nch, cred,
					   LK_EXCLUSIVE, &vp);
		}
		if (error)
			return (error);
	}

	/*
	 * We have a locked vnode and ncp now.  Note that the ncp will
	 * be cleaned up by the caller if nd->nl_nch is left intact.
	 */
	if (vp->v_type == VLNK) {
		error = EMLINK;
		goto bad;
	}
	if (vp->v_type == VSOCK) {
		error = EOPNOTSUPP;
		goto bad;
	}
	if (vp->v_type != VDIR && (fmode & O_DIRECTORY)) {
		error = ENOTDIR;
		goto bad;
	}
	if ((fmode & O_CREAT) == 0) {
		if (fmode & (FWRITE | O_TRUNC)) {
			if (vp->v_type == VDIR) {
				error = EISDIR;
				goto bad;
			}

			/*
			 * Additional checks on vnode (does not substitute
			 * for ncp_writechk()).
			 */
			error = vn_writechk(vp);
			if (error) {
				/*
				 * Special stale handling, re-resolve the
				 * vnode.
				 */
				if (error == ESTALE) {
					u_int dummy_gen = 0;

					vput(vp);
					vp = NULL;
					if (vpexcl == 0) {
						cache_unlock(&nd->nl_nch);
						cache_lock(&nd->nl_nch);
					}
					cache_setunresolved(&nd->nl_nch);
					error = cache_resolve(&nd->nl_nch,
							      &dummy_gen,
							      cred);
					if (error == 0)
						goto again;
				}
				goto bad;
			}
		}
	}
	if (fmode & O_TRUNC) {
		vn_unlock(vp);				/* XXX */
		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);	/* XXX */
		osize = vp->v_filesize;
		VATTR_NULL(vap);
		vap->va_size = 0;
		error = VOP_SETATTR_FP(vp, vap, cred, fp);
		if (error)
			goto bad;
		error = VOP_GETATTR(vp, vap);
		if (error)
			goto bad;
		mp = vq_vptomp(vp);
		VFS_ACCOUNT(mp, vap->va_uid, vap->va_gid, -osize);
	}

	/*
	 * Set or clear VNSWAPCACHE on the vp based on nd->nl_nch.ncp->nc_flag.
	 * These particular bits a tracked all the way from the root.
	 *
	 * NOTE: Might not work properly on NFS servers due to the
	 * disconnected namecache.
	 */
	flags = nd->nl_nch.ncp->nc_flag;
	if ((flags & (NCF_UF_CACHE | NCF_UF_PCACHE)) &&
	    (flags & (NCF_SF_NOCACHE | NCF_SF_PNOCACHE)) == 0) {
		vsetflags(vp, VSWAPCACHE);
	} else {
		vclrflags(vp, VSWAPCACHE);
	}

	/*
	 * Setup the fp so VOP_OPEN can override it.  No descriptor has been
	 * associated with the fp yet so we own it clean.
	 *
	 * f_nchandle inherits nl_nch.  This used to be necessary only for
	 * directories but now we do it unconditionally so f*() ops
	 * such as fchmod() can access the actual namespace that was
	 * used to open the file.
	 */
	if (fp) {
		if (nd->nl_flags & NLC_APPENDONLY)
			fmode |= FAPPENDONLY;
		fp->f_nchandle = nd->nl_nch;
		cache_zero(&nd->nl_nch);
		cache_unlock(&fp->f_nchandle);
	}

	/*
	 * Get rid of nl_nch.  vn_open does not return it (it returns the
	 * vnode or the file pointer).
	 *
	 * NOTE: We can't leave nl_nch locked through the VOP_OPEN anyway
	 *	 since the VOP_OPEN may block, e.g. on /dev/ttyd0
	 *
	 * NOTE: The VOP_OPEN() can replace the *fpp we supply with its own
	 *	 (it will fdrop/fhold), and can also set the *fpp up however
	 *	 it wants, not necessarily using DTYPE_VNODE.
	 */
	if (nd->nl_nch.ncp)
		cache_put(&nd->nl_nch);

	error = VOP_OPEN(vp, fmode, cred, fpp);
	fp = fpp ? *fpp : NULL;

	if (error) {
		/*
		 * setting f_ops to &badfileops will prevent the descriptor
		 * code from trying to close and release the vnode, since
		 * the open failed we do not want to call close.
		 */
		if (fp) {
			fp->f_data = NULL;
			fp->f_ops = &badfileops;
		}
		goto bad;
	}

#if 0
	/*
	 * Assert that VREG files have been setup for vmio.
	 */
	KASSERT(vp->v_type != VREG || vp->v_object != NULL,
		("vn_open: regular file was not VMIO enabled!"));
#endif

	/*
	 * Return the vnode.  XXX needs some cleaning up.  The vnode is
	 * only returned in the fp == NULL case.
	 *
	 * NOTE: vnode stored in fp may be different
	 */
	if (fp == NULL) {
		nd->nl_open_vp = vp;
		nd->nl_vp_fmode = fmode;
		if ((nd->nl_flags & NLC_LOCKVP) == 0)
			vn_unlock(vp);
	} else {
		vput(vp);
	}
	return (0);
bad:
	if (vp)
		vput(vp);
	return (error);
}

int
vn_opendisk(const char *devname, int fmode, struct vnode **vpp)
{
	struct vnode *vp;
	int error;

	if (strncmp(devname, "/dev/", 5) == 0)
		devname += 5;
	if ((vp = getsynthvnode(devname)) == NULL) {
		error = ENODEV;
	} else {
		error = VOP_OPEN(vp, fmode, proc0.p_ucred, NULL);
		vn_unlock(vp);
		if (error) {
			vrele(vp);
			vp = NULL;
		}
	}
	*vpp = vp;
	return (error);
}

/*
 * Checks for special conditions on the vnode which might prevent writing
 * after the vnode has (likely) been locked.  The vnode might or might not
 * be locked as of this call, but will be at least referenced.
 *
 * Also re-checks the mount RDONLY flag that ncp_writechk() checked prior
 * to the vnode being locked.
 */
int
vn_writechk(struct vnode *vp)
{
	/*
	 * If there's shared text associated with
	 * the vnode, try to free it up once.  If
	 * we fail, we can't allow writing.
	 */
	if (vp->v_flag & VTEXT)
		return (ETXTBSY);
	if (vp->v_mount && (vp->v_mount->mnt_flag & MNT_RDONLY))
		return (EROFS);
	return 0;
}

/*
 * Check whether the underlying mount is read-only.  The mount point
 * referenced by the namecache may be different from the mount point
 * used by the underlying vnode in the case of NULLFS, so a separate
 * check is needed.
 *
 * Must be called PRIOR to any vnodes being locked.
 */
int
ncp_writechk(struct nchandle *nch)
{
	struct mount *mp;

	if ((mp = nch->mount) != NULL) {
		if (mp->mnt_flag & MNT_RDONLY)
			return (EROFS);
		if (mp->mnt_op->vfs_modifying != vfs_stdmodifying)
			VFS_MODIFYING(mp);
	}
	return(0);
}

/*
 * Vnode close call
 *
 * MPSAFE
 */
int
vn_close(struct vnode *vp, int flags, struct file *fp)
{
	int error;

	error = vn_lock(vp, LK_SHARED | LK_RETRY | LK_FAILRECLAIM);
	if (error == 0) {
		error = VOP_CLOSE(vp, flags, fp);
		vn_unlock(vp);
	}
	vrele(vp);
	return (error);
}

/*
 * Sequential heuristic.
 *
 * MPSAFE (f_seqcount and f_nextoff are allowed to race)
 */
static __inline
int
sequential_heuristic(struct uio *uio, struct file *fp)
{
	/*
	 * Sequential heuristic - detect sequential operation
	 *
	 * NOTE: SMP: We allow f_seqcount updates to race.
	 */
	if ((uio->uio_offset == 0 && fp->f_seqcount > 0) ||
	    uio->uio_offset == fp->f_nextoff) {
		int tmpseq = fp->f_seqcount;

		tmpseq += howmany(uio->uio_resid, MAXBSIZE);
		if (tmpseq > IO_SEQMAX)
			tmpseq = IO_SEQMAX;
		fp->f_seqcount = tmpseq;
		return(fp->f_seqcount << IO_SEQSHIFT);
	}

	/*
	 * Not sequential, quick draw-down of seqcount
	 *
	 * NOTE: SMP: We allow f_seqcount updates to race.
	 */
	if (fp->f_seqcount > 1)
		fp->f_seqcount = 1;
	else
		fp->f_seqcount = 0;
	return(0);
}

/*
 * get - lock and return the f_offset field.
 * set - set and unlock the f_offset field.
 *
 * These routines serve the dual purpose of serializing access to the
 * f_offset field (at least on x86) and guaranteeing operational integrity
 * when multiple read()ers and write()ers are present on the same fp.
 *
 * MPSAFE
 */
static __inline off_t
vn_get_fpf_offset(struct file *fp)
{
	u_int	flags;
	u_int	nflags;

	/*
	 * Shortcut critical path.
	 */
	flags = fp->f_flag & ~FOFFSETLOCK;
	if (atomic_cmpset_int(&fp->f_flag, flags, flags | FOFFSETLOCK))
		return(fp->f_offset);

	/*
	 * The hard way
	 */
	for (;;) {
		flags = fp->f_flag;
		if (flags & FOFFSETLOCK) {
			nflags = flags | FOFFSETWAKE;
			tsleep_interlock(&fp->f_flag, 0);
			if (atomic_cmpset_int(&fp->f_flag, flags, nflags))
				tsleep(&fp->f_flag, PINTERLOCKED, "fpoff", 0);
		} else {
			nflags = flags | FOFFSETLOCK;
			if (atomic_cmpset_int(&fp->f_flag, flags, nflags))
				break;
		}
	}
	return(fp->f_offset);
}

/*
 * MPSAFE
 */
static __inline void
vn_set_fpf_offset(struct file *fp, off_t offset)
{
	u_int	flags;
	u_int	nflags;

	/*
	 * We hold the lock so we can set the offset without interference.
	 */
	fp->f_offset = offset;

	/*
	 * Normal release is already a reasonably critical path.
	 */
	for (;;) {
		flags = fp->f_flag;
		nflags = flags & ~(FOFFSETLOCK | FOFFSETWAKE);
		if (atomic_cmpset_int(&fp->f_flag, flags, nflags)) {
			if (flags & FOFFSETWAKE)
				wakeup(&fp->f_flag);
			break;
		}
	}
}

/*
 * MPSAFE
 */
static __inline off_t
vn_poll_fpf_offset(struct file *fp)
{
#if defined(__x86_64__)
	return(fp->f_offset);
#else
	off_t off = vn_get_fpf_offset(fp);
	vn_set_fpf_offset(fp, off);
	return(off);
#endif
}

/*
 * Package up an I/O request on a vnode into a uio and do it.
 *
 * MPSAFE
 */
int
vn_rdwr(enum uio_rw rw, struct vnode *vp, caddr_t base, int len,
	off_t offset, enum uio_seg segflg, int ioflg,
	struct ucred *cred, int *aresid)
{
	struct uio auio;
	struct iovec aiov;
	int error;

	if ((ioflg & IO_NODELOCKED) == 0)
		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
	auio.uio_iov = &aiov;
	auio.uio_iovcnt = 1;
	aiov.iov_base = base;
	aiov.iov_len = len;
	auio.uio_resid = len;
	auio.uio_offset = offset;
	auio.uio_segflg = segflg;
	auio.uio_rw = rw;
	auio.uio_td = curthread;
	if (rw == UIO_READ) {
		error = VOP_READ(vp, &auio, ioflg, cred);
	} else {
		error = VOP_WRITE(vp, &auio, ioflg, cred);
	}
	if (aresid)
		*aresid = auio.uio_resid;
	else
		if (auio.uio_resid && error == 0)
			error = EIO;
	if ((ioflg & IO_NODELOCKED) == 0)
		vn_unlock(vp);
	return (error);
}

/*
 * Package up an I/O request on a vnode into a uio and do it.  The I/O
 * request is split up into smaller chunks and we try to avoid saturating
 * the buffer cache while potentially holding a vnode locked, so we
 * check bwillwrite() before calling vn_rdwr().  We also call lwkt_user_yield()
 * to give other processes a chance to lock the vnode (either other processes
 * core'ing the same binary, or unrelated processes scanning the directory).
 *
 * MPSAFE
 */
int
vn_rdwr_inchunks(enum uio_rw rw, struct vnode *vp, caddr_t base, int len,
		 off_t offset, enum uio_seg segflg, int ioflg,
		 struct ucred *cred, int *aresid)
{
	int error = 0;

	do {
		int chunk;

		/*
		 * Force `offset' to a multiple of MAXBSIZE except possibly
		 * for the first chunk, so that filesystems only need to
		 * write full blocks except possibly for the first and last
		 * chunks.
		 */
		chunk = MAXBSIZE - (uoff_t)offset % MAXBSIZE;

		if (chunk > len)
			chunk = len;
		if (vp->v_type == VREG && (ioflg & IO_RECURSE) == 0) {
			switch(rw) {
			case UIO_READ:
				bwillread(chunk);
				break;
			case UIO_WRITE:
				bwillwrite(chunk);
				break;
			}
		}
		error = vn_rdwr(rw, vp, base, chunk, offset, segflg,
				ioflg, cred, aresid);
		len -= chunk;	/* aresid calc already includes length */
		if (error)
			break;
		offset += chunk;
		base += chunk;
		lwkt_user_yield();
	} while (len);
	if (aresid)
		*aresid += len;
	return (error);
}

/*
 * File pointers can no longer get ripped up by revoke so
 * we don't need to lock access to the vp.
 *
 * f_offset updates are not guaranteed against multiple readers
 */
static int
vn_read(struct file *fp, struct uio *uio, struct ucred *cred, int flags)
{
	struct vnode *vp;
	int error, ioflag;

	KASSERT(uio->uio_td == curthread,
		("uio_td %p is not td %p", uio->uio_td, curthread));
	vp = (struct vnode *)fp->f_data;

	ioflag = 0;
	if (flags & O_FBLOCKING) {
		/* ioflag &= ~IO_NDELAY; */
	} else if (flags & O_FNONBLOCKING) {
		ioflag |= IO_NDELAY;
	} else if (fp->f_flag & FNONBLOCK) {
		ioflag |= IO_NDELAY;
	}
	if (fp->f_flag & O_DIRECT) {
		ioflag |= IO_DIRECT;
	}
	if ((flags & O_FOFFSET) == 0 && (vp->v_flag & VNOTSEEKABLE) == 0)
		uio->uio_offset = vn_get_fpf_offset(fp);
	vn_lock(vp, LK_SHARED | LK_RETRY);
	ioflag |= sequential_heuristic(uio, fp);

	error = VOP_READ_FP(vp, uio, ioflag, cred, fp);
	fp->f_nextoff = uio->uio_offset;
	vn_unlock(vp);
	if ((flags & O_FOFFSET) == 0 && (vp->v_flag & VNOTSEEKABLE) == 0)
		vn_set_fpf_offset(fp, uio->uio_offset);
	return (error);
}

/*
 * MPSAFE
 */
static int
vn_write(struct file *fp, struct uio *uio, struct ucred *cred, int flags)
{
	struct vnode *vp;
	int error, ioflag;

	KASSERT(uio->uio_td == curthread,
		("uio_td %p is not p %p", uio->uio_td, curthread));
	vp = (struct vnode *)fp->f_data;

	ioflag = IO_UNIT;
	if (vp->v_type == VREG &&
	   ((fp->f_flag & O_APPEND) || (flags & O_FAPPEND))) {
		ioflag |= IO_APPEND;
	}

	if (flags & O_FBLOCKING) {
		/* ioflag &= ~IO_NDELAY; */
	} else if (flags & O_FNONBLOCKING) {
		ioflag |= IO_NDELAY;
	} else if (fp->f_flag & FNONBLOCK) {
		ioflag |= IO_NDELAY;
	}
	if (fp->f_flag & O_DIRECT) {
		ioflag |= IO_DIRECT;
	}
	if (flags & O_FASYNCWRITE) {
		/* ioflag &= ~IO_SYNC; */
	} else if (flags & O_FSYNCWRITE) {
		ioflag |= IO_SYNC;
	} else if (fp->f_flag & O_FSYNC) {
		ioflag |= IO_SYNC;
	}

	if (vp->v_mount && (vp->v_mount->mnt_flag & MNT_SYNCHRONOUS))
		ioflag |= IO_SYNC;
	if ((flags & O_FOFFSET) == 0)
		uio->uio_offset = vn_get_fpf_offset(fp);
	if (vp->v_mount)
		VFS_MODIFYING(vp->v_mount);
	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
	ioflag |= sequential_heuristic(uio, fp);
	error = VOP_WRITE_FP(vp, uio, ioflag, cred, fp);
	fp->f_nextoff = uio->uio_offset;
	vn_unlock(vp);
	if ((flags & O_FOFFSET) == 0)
		vn_set_fpf_offset(fp, uio->uio_offset);
	return (error);
}

/*
 * MPSAFE
 */
static int
vn_statfile(struct file *fp, struct stat *sb, struct ucred *cred)
{
	struct vnode *vp;
	int error;

	vp = (struct vnode *)fp->f_data;
	error = vn_stat(vp, sb, cred);
	return (error);
}

/*
 * MPSAFE
 */
int
vn_stat(struct vnode *vp, struct stat *sb, struct ucred *cred)
{
	struct vattr vattr;
	struct vattr *vap;
	int error;
	u_short mode;
	cdev_t dev;

	/*
	 * vp already has a ref and is validated, can call unlocked.
	 */
	vap = &vattr;
	error = VOP_GETATTR(vp, vap);
	if (error)
		return (error);

	/*
	 * Zero the spare stat fields
	 */
	sb->st_lspare = 0;
	sb->st_qspare2 = 0;

	/*
	 * Copy from vattr table
	 */
	if (vap->va_fsid != VNOVAL)
		sb->st_dev = vap->va_fsid;
	else
		sb->st_dev = vp->v_mount->mnt_stat.f_fsid.val[0];
	sb->st_ino = vap->va_fileid;
	mode = vap->va_mode;
	switch (vap->va_type) {
	case VREG:
		mode |= S_IFREG;
		break;
	case VDATABASE:
		mode |= S_IFDB;
		break;
	case VDIR:
		mode |= S_IFDIR;
		break;
	case VBLK:
		mode |= S_IFBLK;
		break;
	case VCHR:
		mode |= S_IFCHR;
		break;
	case VLNK:
		mode |= S_IFLNK;
		/* This is a cosmetic change, symlinks do not have a mode. */
		if (vp->v_mount->mnt_flag & MNT_NOSYMFOLLOW)
			sb->st_mode &= ~ACCESSPERMS;	/* 0000 */
		else
			sb->st_mode |= ACCESSPERMS;	/* 0777 */
		break;
	case VSOCK:
		mode |= S_IFSOCK;
		break;
	case VFIFO:
		mode |= S_IFIFO;
		break;
	default:
		return (EBADF);
	}
	sb->st_mode = mode;
	if (vap->va_nlink > (nlink_t)-1)
		sb->st_nlink = (nlink_t)-1;
	else
		sb->st_nlink = vap->va_nlink;
	sb->st_uid = vap->va_uid;
	sb->st_gid = vap->va_gid;
	sb->st_rdev = devid_from_dev(vp->v_rdev);
	sb->st_size = vap->va_size;
	sb->st_atimespec = vap->va_atime;
	sb->st_mtimespec = vap->va_mtime;
	sb->st_ctimespec = vap->va_ctime;

	/*
	 * A VCHR and VBLK device may track the last access and last modified
	 * time independantly of the filesystem.  This is particularly true
	 * because device read and write calls may bypass the filesystem.
	 */
	if (vp->v_type == VCHR || vp->v_type == VBLK) {
		dev = vp->v_rdev;
		if (dev != NULL) {
			if (dev->si_lastread) {
				sb->st_atimespec.tv_sec = time_second +
							  (dev->si_lastread -
							   time_uptime);
				sb->st_atimespec.tv_nsec = 0;
			}
			if (dev->si_lastwrite) {
				sb->st_mtimespec.tv_sec = time_second +
							  (dev->si_lastwrite -
							   time_uptime);
				sb->st_mtimespec.tv_nsec = 0;
			}
		}
	}

        /*
	 * According to www.opengroup.org, the meaning of st_blksize is
	 *   "a filesystem-specific preferred I/O block size for this
	 *    object.  In some filesystem types, this may vary from file
	 *    to file"
	 * Default to PAGE_SIZE after much discussion.
	 */

	if (vap->va_type == VREG) {
		sb->st_blksize = vap->va_blocksize;
	} else if (vn_isdisk(vp, NULL)) {
		/*
		 * XXX this is broken.  If the device is not yet open (aka
		 * stat() call, aka v_rdev == NULL), how are we supposed
		 * to get a valid block size out of it?
		 */
		dev = vp->v_rdev;

		sb->st_blksize = dev->si_bsize_best;
		if (sb->st_blksize < dev->si_bsize_phys)
			sb->st_blksize = dev->si_bsize_phys;
		if (sb->st_blksize < BLKDEV_IOSIZE)
			sb->st_blksize = BLKDEV_IOSIZE;
	} else {
		sb->st_blksize = PAGE_SIZE;
	}

	sb->st_flags = vap->va_flags;

	error = caps_priv_check(cred, SYSCAP_NOVFS_GENERATION);
	if (error)
		sb->st_gen = 0;
	else
		sb->st_gen = (u_int32_t)vap->va_gen;

	sb->st_blocks = vap->va_bytes / S_BLKSIZE;

	/*
	 * This is for ABI compatibility <= 5.7 (for ABI change made in
	 * 5.7 master).
	 */
	sb->__old_st_blksize = sb->st_blksize;

	return (0);
}

/*
 * MPALMOSTSAFE - acquires mplock
 */
static int
vn_ioctl(struct file *fp, u_long com, caddr_t data, struct ucred *ucred,
	 struct sysmsg *msg)
{
	struct vnode *vp = ((struct vnode *)fp->f_data);
	struct vnode *ovp;
	struct vattr vattr;
	int error;
	off_t size;

	switch (vp->v_type) {
	case VREG:
	case VDIR:
		if (com == FIONREAD) {
			error = VOP_GETATTR(vp, &vattr);
			if (error)
				break;
			size = vattr.va_size;
			if ((vp->v_flag & VNOTSEEKABLE) == 0)
				size -= vn_poll_fpf_offset(fp);
			if (size > 0x7FFFFFFF)
				size = 0x7FFFFFFF;
			*(int *)data = size;
			error = 0;
			break;
		}
		if (com == FIOASYNC) {				/* XXX */
			error = 0;				/* XXX */
			break;
		}
		/* fall into ... */
	default:
#if 0
		return (ENOTTY);
#endif
	case VFIFO:
	case VCHR:
	case VBLK:
		if (com == FIODTYPE) {
			if (vp->v_type != VCHR && vp->v_type != VBLK) {
				error = ENOTTY;
				break;
			}
			*(int *)data = dev_dflags(vp->v_rdev) & D_TYPEMASK;
			error = 0;
			break;
		}
		error = VOP_IOCTL(vp, com, data, fp->f_flag, ucred, msg);
		if (error == 0 && com == TIOCSCTTY) {
			struct proc *p = curthread->td_proc;
			struct session *sess;

			if (p == NULL) {
				error = ENOTTY;
				break;
			}

			get_mplock();
			sess = p->p_session;
			/* Do nothing if reassigning same control tty */
			if (sess->s_ttyvp == vp) {
				error = 0;
				rel_mplock();
				break;
			}

			/* Get rid of reference to old control tty */
			ovp = sess->s_ttyvp;
			vref(vp);
			sess->s_ttyvp = vp;
			if (ovp)
				vrele(ovp);
			rel_mplock();
		}
		break;
	}
	return (error);
}

/*
 * Obtain the requested vnode lock
 *
 *	LK_RETRY	Automatically retry on timeout
 *	LK_FAILRECLAIM	Fail if the vnode is being reclaimed
 *
 * Failures will occur if the vnode is undergoing recyclement, but not
 * all callers expect that the function will fail so the caller must pass
 * LK_FAILOK if it wants to process an error code.
 *
 * Errors can occur for other reasons if you pass in other LK_ flags,
 * regardless of whether you pass in LK_FAILRECLAIM
 */
int
vn_lock(struct vnode *vp, int flags)
{
	int error;

	do {
		error = lockmgr(&vp->v_lock, flags);
		if (error == 0)
			break;
	} while (flags & LK_RETRY);

	/*
	 * Because we (had better!) have a ref on the vnode, once it
	 * goes to VRECLAIMED state it will not be recycled until all
	 * refs go away.  So we can just check the flag.
	 */
	if (error == 0 && (vp->v_flag & VRECLAIMED)) {
		if (flags & LK_FAILRECLAIM) {
			lockmgr(&vp->v_lock, LK_RELEASE);
			error = ENOENT;
		}
	}
	return (error);
}

int
vn_relock(struct vnode *vp, int flags)
{
	int error;

	do {
		error = lockmgr(&vp->v_lock, flags);
		if (error == 0)
			break;
	} while (flags & LK_RETRY);

	return error;
}

#ifdef DEBUG_VN_UNLOCK

void
debug_vn_unlock(struct vnode *vp, const char *filename, int line)
{
	kprintf("vn_unlock from %s:%d\n", filename, line);
	lockmgr(&vp->v_lock, LK_RELEASE);
}

#else

void
vn_unlock(struct vnode *vp)
{
	lockmgr(&vp->v_lock, LK_RELEASE);
}

#endif

/*
 * MPSAFE
 */
int
vn_islocked(struct vnode *vp)
{
	return (lockstatus(&vp->v_lock, curthread));
}

/*
 * Return the lock status of a vnode and unlock the vnode
 * if we owned the lock.  This is not a boolean, if the
 * caller cares what the lock status is the caller must
 * check the various possible values.
 *
 * This only unlocks exclusive locks held by the caller,
 * it will NOT unlock shared locks (there is no way to
 * tell who the shared lock belongs to).
 *
 * MPSAFE
 */
int
vn_islocked_unlock(struct vnode *vp)
{
	int vpls;

	vpls = lockstatus(&vp->v_lock, curthread);
	if (vpls == LK_EXCLUSIVE)
		lockmgr(&vp->v_lock, LK_RELEASE);
	return(vpls);
}

/*
 * Restore a vnode lock that we previously released via
 * vn_islocked_unlock().  This is a NOP if we did not
 * own the original lock.
 *
 * MPSAFE
 */
void
vn_islocked_relock(struct vnode *vp, int vpls)
{
	int error;

	if (vpls == LK_EXCLUSIVE)
		error = lockmgr(&vp->v_lock, vpls);
}

/*
 * MPSAFE
 */
static int
vn_closefile(struct file *fp)
{
	int error;

	fp->f_ops = &badfileops;
	error = vn_close(((struct vnode *)fp->f_data), fp->f_flag, fp);
	return (error);
}

/*
 * MPSAFE
 */
static int
vn_kqfilter(struct file *fp, struct knote *kn)
{
	int error;

	error = VOP_KQFILTER(((struct vnode *)fp->f_data), kn);
	return (error);
}

int
vn_bmap_seekhole_locked(struct vnode *vp, u_long cmd, off_t *off,
    struct ucred *cred)
{
	struct vattr vattr;
	off_t size;
	uint64_t bsize;
	off_t noff, doff;
	int error;

	KASSERT(cmd == FIOSEEKHOLE || cmd == FIOSEEKDATA,
	    ("%s: Wrong command %lu", __func__, cmd));
	KKASSERT(vn_islocked(vp) == LK_EXCLUSIVE);

	if (vp->v_type != VREG) {
		error = ENOTTY;
		goto out;
	}
	error = VOP_GETATTR(vp, &vattr);
	if (vattr.va_size <= OFF_MAX)
		size = vattr.va_size;
	else
		error = EFBIG;
	if (error != 0)
		goto out;
	noff = *off;
	if (noff < 0 || noff >= size) {
		error = ENXIO;
		goto out;
	}

	vm_object_page_clean(vp->v_object, 0, 0, OBJPC_SYNC);

	bsize = vp->v_mount->mnt_stat.f_iosize;
	for (; noff < size; noff += bsize - noff % bsize) {
		error = VOP_BMAP(vp, noff, &doff, NULL, NULL, BUF_CMD_SEEK);
		if (error == EOPNOTSUPP) {
			error = ENOTTY;
			goto out;
		}
		if ((doff == NOOFFSET && cmd == FIOSEEKHOLE) ||
		    (doff != NOOFFSET && cmd == FIOSEEKDATA)) {
			if (noff < *off)
				noff = *off;
			goto out;
		}
	}
	if (noff > size)
		noff = size;
	/* noff == size. There is an implicit hole at the end of file. */
	if (cmd == FIOSEEKDATA)
		error = ENXIO;
out:
	if (error == 0)
		*off = noff;
	return (error);
}

int
vn_bmap_seekhole(struct vnode *vp, u_long cmd, off_t *off, struct ucred *cred)
{
	int error;

	KASSERT(cmd == FIOSEEKHOLE || cmd == FIOSEEKDATA,
	    ("%s: Wrong command %lu", __func__, cmd));

	if (vn_lock(vp, LK_EXCLUSIVE) != 0)
		return (EBADF);
	error = vn_bmap_seekhole_locked(vp, cmd, off, cred);
	vn_unlock(vp);
	return (error);
}

int
vn_seek(struct file *fp, off_t offset, int whence, off_t *res)
{
	/*
	 * NOTE: devfs_dev_fileops uses exact same code
	 */
	struct thread *td = curthread;
	struct vnode *vp;
	struct vattr_lite lva;
	off_t new_offset;
	int error;

	vp = (struct vnode *)fp->f_data;

	switch (whence) {
	case L_INCR:
		spin_lock(&fp->f_spin);
		new_offset = fp->f_offset + offset;
		error = 0;
		break;
	case L_XTND:
		error = VOP_GETATTR_LITE(vp, &lva);
		spin_lock(&fp->f_spin);
		new_offset = offset + lva.va_size;
		break;
	case L_SET:
		new_offset = offset;
		error = 0;
		spin_lock(&fp->f_spin);
		break;
	case SEEK_DATA:
		error = fo_ioctl(fp, FIOSEEKDATA, (caddr_t)&offset,
		    td->td_ucred, NULL);
		if (error == ENOTTY)
			error = EINVAL;
		new_offset = offset;
		spin_lock(&fp->f_spin);
		break;
	case SEEK_HOLE:
		error = fo_ioctl(fp, FIOSEEKHOLE, (caddr_t)&offset,
		    td->td_ucred, NULL);
		if (error == ENOTTY)
			error = EINVAL;
		new_offset = offset;
		spin_lock(&fp->f_spin);
		break;
	default:
		new_offset = 0;
		error = EINVAL;
		spin_lock(&fp->f_spin);
		break;
	}

	/*
	 * Validate the seek position.  Negative offsets are not allowed
	 * for regular files or directories.
	 *
	 * Normally we would also not want to allow negative offsets for
	 * character and block-special devices.  However kvm addresses
	 * on 64 bit architectures might appear to be negative and must
	 * be allowed.
	 */
	if (error == 0) {
		if (new_offset < 0 &&
		    (vp->v_type == VREG || vp->v_type == VDIR)) {
			error = EINVAL;
		} else {
			fp->f_offset = new_offset;
		}
	}
	*res = fp->f_offset;
	spin_unlock(&fp->f_spin);

	return (error);
}