Rename printf -> kprintf in sys/ and add some defines where necessary

[dragonfly.git] / sys / vfs / union / union_vfsops.c

/*
 * Copyright (c) 1994, 1995 The Regents of the University of California.
 * Copyright (c) 1994, 1995 Jan-Simon Pendry.
 * All rights reserved.
 *
 * This code is derived from software donated to Berkeley by
 * Jan-Simon Pendry.
 *
 * 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.
 *
 *	@(#)union_vfsops.c	8.20 (Berkeley) 5/20/95
 * $FreeBSD: src/sys/miscfs/union/union_vfsops.c,v 1.39.2.2 2001/10/25 19:18:53 dillon Exp $
 * $DragonFly: src/sys/vfs/union/union_vfsops.c,v 1.29 2006/12/23 00:41:30 swildner Exp $
 */

/*
 * Union Layer
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/nlookup.h>
#include <sys/namei.h>
#include <sys/malloc.h>
#include <sys/filedesc.h>
#include "union.h"
#include <vm/vm_zone.h>

extern struct vop_ops union_vnode_vops;

static MALLOC_DEFINE(M_UNIONFSMNT, "UNION mount", "UNION mount structure");

extern int	union_init (struct vfsconf *);
static int	union_mount (struct mount *mp, char *path, caddr_t data,
				 struct ucred *cred);
static int	union_root (struct mount *mp, struct vnode **vpp);
static int	union_statfs (struct mount *mp, struct statfs *sbp,
				struct ucred *cred);
static int	union_unmount (struct mount *mp, int mntflags);

/*
 * Mount union filesystem
 */
static int
union_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred)
{
	int error = 0;
	struct union_args args;
	struct vnode *lowerrootvp = NULLVP;
	struct vnode *upperrootvp = NULLVP;
	struct union_mount *um = 0;
	struct ucred *cred = 0;
	struct nlookupdata nd;
	char *cp = 0;
	int len;
	u_int size;

	UDEBUG(("union_mount(mp = %p)\n", (void *)mp));

	/*
	 * Disable clustered write, otherwise system becomes unstable.
	 */
	mp->mnt_flag |= MNT_NOCLUSTERW;

	/*
	 * Update is a no-op
	 */
	if (mp->mnt_flag & MNT_UPDATE) {
		/*
		 * Need to provide.
		 * 1. a way to convert between rdonly and rdwr mounts.
		 * 2. support for nfs exports.
		 */
		error = EOPNOTSUPP;
		goto bad;
	}

	/*
	 * Get argument
	 */
	error = copyin(data, (caddr_t)&args, sizeof(struct union_args));
	if (error)
		goto bad;

	/*
	 * Obtain lower vnode. 
	 */

	lowerrootvp = mp->mnt_vnodecovered;
	vref(lowerrootvp);

#if 0
	/*
	 * Unlock lower node to avoid deadlock.
	 */
	if (lowerrootvp->v_tag == VT_UNION)
		vn_unlock(lowerrootvp);
#endif

	/*
	 * Obtain upper vnode by calling nlookup() on the path.  The
	 * upperrootvp will be turned referenced but not locked.
	 */
	error = nlookup_init(&nd, args.target, UIO_USERSPACE, NLC_FOLLOW);
	if (error == 0)
		error = nlookup(&nd);
	if (error == 0)
		error = cache_vref(&nd.nl_nch, nd.nl_cred, &upperrootvp);
	nlookup_done(&nd);
	if (error)
		goto bad;

	UDEBUG(("mount_root UPPERVP %p locked = %d\n", upperrootvp,
	    vn_islocked(upperrootvp)));

	/*
	 * Check multi union mount to avoid `lock myself again' panic.
	 * Also require that it be a directory.
	 */
	if (upperrootvp == VTOUNION(lowerrootvp)->un_uppervp) {
#ifdef DIAGNOSTIC
		kprintf("union_mount: multi union mount?\n");
#endif
		error = EDEADLK;
		goto bad;
	}

	if (upperrootvp->v_type != VDIR) {
		error = EINVAL;
		goto bad;
	}

	/*
	 * Allocate our union_mount structure and populate the fields.
	 * The vnode references are stored in the union_mount as held,
	 * unlocked references.  Depending on the _BELOW flag, the
	 * filesystems are viewed in a different order.  In effect this
	 * is the same as providing a mount-under option to the mount
	 * syscall.
	 */

	um = (struct union_mount *) malloc(sizeof(struct union_mount),
				M_UNIONFSMNT, M_WAITOK);

	bzero(um, sizeof(struct union_mount));

	um->um_op = args.mntflags & UNMNT_OPMASK;

	switch (um->um_op) {
	case UNMNT_ABOVE:
		um->um_lowervp = lowerrootvp;
		um->um_uppervp = upperrootvp;
		upperrootvp = NULL;
		lowerrootvp = NULL;
		break;

	case UNMNT_BELOW:
		um->um_lowervp = upperrootvp;
		um->um_uppervp = lowerrootvp;
		upperrootvp = NULL;
		lowerrootvp = NULL;
		break;

	case UNMNT_REPLACE:
		vrele(lowerrootvp);
		lowerrootvp = NULL;
		um->um_uppervp = upperrootvp;
		um->um_lowervp = lowerrootvp;
		upperrootvp = NULL;
		break;

	default:
		error = EINVAL;
		goto bad;
	}

	/*
	 * Unless the mount is readonly, ensure that the top layer
	 * supports whiteout operations
	 */
	if ((mp->mnt_flag & MNT_RDONLY) == 0) {
		error = VOP_WHITEOUT(um->um_uppervp, NULL, NAMEI_LOOKUP);
		if (error)
			goto bad;
	}

	/*
	 * File creds and modes for shadowed files are based on the user
	 * that did the mount.
	 */
	um->um_cred = crhold(cred);
	um->um_cmode = UN_DIRMODE;
	if (curproc)
		um->um_cmode &= ~curproc->p_fd->fd_cmask;

	/*
	 * Depending on what you think the MNT_LOCAL flag might mean,
	 * you may want the && to be || on the conditional below.
	 * At the moment it has been defined that the filesystem is
	 * only local if it is all local, ie the MNT_LOCAL flag implies
	 * that the entire namespace is local.  If you think the MNT_LOCAL
	 * flag implies that some of the files might be stored locally
	 * then you will want to change the conditional.
	 */
	if (um->um_op == UNMNT_ABOVE) {
		if (((um->um_lowervp == NULLVP) ||
		     (um->um_lowervp->v_mount->mnt_flag & MNT_LOCAL)) &&
		    (um->um_uppervp->v_mount->mnt_flag & MNT_LOCAL))
			mp->mnt_flag |= MNT_LOCAL;
	}

	/*
	 * Copy in the upper layer's RDONLY flag.  This is for the benefit
	 * of lookup() which explicitly checks the flag, rather than asking
	 * the filesystem for its own opinion.  This means, that an update
	 * mount of the underlying filesystem to go from rdonly to rdwr
	 * will leave the unioned view as read-only.
	 */
	mp->mnt_flag |= (um->um_uppervp->v_mount->mnt_flag & MNT_RDONLY);

	mp->mnt_data = (qaddr_t) um;
	vfs_getnewfsid(mp);

	switch (um->um_op) {
	case UNMNT_ABOVE:
		cp = "<above>:";
		break;
	case UNMNT_BELOW:
		cp = "<below>:";
		break;
	case UNMNT_REPLACE:
		cp = "";
		break;
	}
	len = strlen(cp);
	bcopy(cp, mp->mnt_stat.f_mntfromname, len);

	cp = mp->mnt_stat.f_mntfromname + len;
	len = MNAMELEN - len;

	(void) copyinstr(args.target, cp, len - 1, &size);
	bzero(cp + size, len - size);

	vfs_add_vnodeops(mp, &union_vnode_vops, &mp->mnt_vn_norm_ops);

	(void)union_statfs(mp, &mp->mnt_stat, cred);

	return (0);

bad:
	if (um) {
		if (um->um_uppervp)
			vrele(um->um_uppervp);
		if (um->um_lowervp)
			vrele(um->um_lowervp);
		/* XXX other fields */
		kfree(um, M_UNIONFSMNT);
	}
	if (cred)
		crfree(cred);
	if (upperrootvp)
		vrele(upperrootvp);
	if (lowerrootvp)
		vrele(lowerrootvp);
	return (error);
}

/*
 * Free reference to union layer
 */
static int
union_unmount(struct mount *mp, int mntflags)
{
	struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
	int error;
	int freeing;
	int flags = 0;

	UDEBUG(("union_unmount(mp = %p)\n", (void *)mp));

	if (mntflags & MNT_FORCE)
		flags |= FORCECLOSE;

	/*
	 * Keep flushing vnodes from the mount list.
	 * This is needed because of the un_pvp held
	 * reference to the parent vnode.
	 * If more vnodes have been freed on a given pass,
	 * the try again.  The loop will iterate at most
	 * (d) times, where (d) is the maximum tree depth
	 * in the filesystem.
	 */
	for (freeing = 0; (error = vflush(mp, 0, flags)) != 0;) {
		int n = mp->mnt_nvnodelistsize;

		/* if this is unchanged then stop */
		if (n == freeing)
			break;

		/* otherwise try once more time */
		freeing = n;
	}

	/* If the most recent vflush failed, the filesystem is still busy. */
	if (error)
		return (error);

	/*
	 * Discard references to upper and lower target vnodes.
	 */
	if (um->um_lowervp)
		vrele(um->um_lowervp);
	vrele(um->um_uppervp);
	crfree(um->um_cred);
	/*
	 * Finally, throw away the union_mount structure
	 */
	kfree(mp->mnt_data, M_UNIONFSMNT);	/* XXX */
	mp->mnt_data = 0;
	return (0);
}

static int
union_root(struct mount *mp, struct vnode **vpp)
{
	struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
	int error;

	/*
	 * Supply an unlocked reference to um_uppervp and to um_lowervp.  It
	 * is possible for um_uppervp to be locked without the associated
	 * root union_node being locked.  We let union_allocvp() deal with
	 * it.
	 */
	UDEBUG(("union_root UPPERVP %p locked = %d\n", um->um_uppervp,
	    vn_islocked(um->um_uppervp)));

	vref(um->um_uppervp);
	if (um->um_lowervp)
		vref(um->um_lowervp);

	error = union_allocvp(vpp, mp, NULLVP, NULLVP, NULL, 
		    um->um_uppervp, um->um_lowervp, 1);
	UDEBUG(("error %d\n", error));
	UDEBUG(("union_root2 UPPERVP %p locked = %d\n", um->um_uppervp,
	    vn_islocked(um->um_uppervp)));

	return (error);
}

static int
union_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred)
{
	int error;
	struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
	struct statfs mstat;
	int lbsize;

	UDEBUG(("union_statfs(mp = %p, lvp = %p, uvp = %p)\n",
	    (void *)mp, (void *)um->um_lowervp, (void *)um->um_uppervp));

	bzero(&mstat, sizeof(mstat));

	if (um->um_lowervp) {
		error = VFS_STATFS(um->um_lowervp->v_mount, &mstat, cred);
		if (error)
			return (error);
	}

	/* now copy across the "interesting" information and fake the rest */
#if 0
	sbp->f_type = mstat.f_type;
	sbp->f_flags = mstat.f_flags;
	sbp->f_bsize = mstat.f_bsize;
	sbp->f_iosize = mstat.f_iosize;
#endif
	lbsize = mstat.f_bsize;
	sbp->f_blocks = mstat.f_blocks;
	sbp->f_bfree = mstat.f_bfree;
	sbp->f_bavail = mstat.f_bavail;
	sbp->f_files = mstat.f_files;
	sbp->f_ffree = mstat.f_ffree;

	error = VFS_STATFS(um->um_uppervp->v_mount, &mstat, cred);
	if (error)
		return (error);

	sbp->f_flags = mstat.f_flags;
	sbp->f_bsize = mstat.f_bsize;
	sbp->f_iosize = mstat.f_iosize;

	/*
	 * if the lower and upper blocksizes differ, then frig the
	 * block counts so that the sizes reported by df make some
	 * kind of sense.  none of this makes sense though.
	 */

	if (mstat.f_bsize != lbsize)
		sbp->f_blocks = ((off_t) sbp->f_blocks * lbsize) / mstat.f_bsize;

	/*
	 * The "total" fields count total resources in all layers,
	 * the "free" fields count only those resources which are
	 * free in the upper layer (since only the upper layer
	 * is writeable).
	 */
	sbp->f_blocks += mstat.f_blocks;
	sbp->f_bfree = mstat.f_bfree;
	sbp->f_bavail = mstat.f_bavail;
	sbp->f_files += mstat.f_files;
	sbp->f_ffree = mstat.f_ffree;

	if (sbp != &mp->mnt_stat) {
		sbp->f_type = mp->mnt_vfc->vfc_typenum;
		bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid));
		bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
	}
	return (0);
}

static struct vfsops union_vfsops = {
	.vfs_mount =     	union_mount,
	.vfs_unmount =     	union_unmount,
	.vfs_root =     	union_root,
	.vfs_statfs =     	union_statfs,
	.vfs_sync =     	vfs_stdsync,
	.vfs_init =     	union_init
};

VFS_SET(union_vfsops, union, VFCF_LOOPBACK);