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+/*
+ * 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
+ * $FreeBSD$
+ */
+
+/*
+ * 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/namei.h>
+#include <sys/malloc.h>
+#include <sys/filedesc.h>
+#include <miscfs/union/union.h>
+#include <vm/vm_zone.h>
+
+static MALLOC_DEFINE(M_UNIONFSMNT, "UNION mount", "UNION mount structure");
+
+extern int union_init __P((struct vfsconf *));
+static int union_mount __P((struct mount *mp, char *path, caddr_t data,
+ struct nameidata *ndp, struct proc *p));
+static int union_root __P((struct mount *mp, struct vnode **vpp));
+static int union_statfs __P((struct mount *mp, struct statfs *sbp,
+ struct proc *p));
+static int union_unmount __P((struct mount *mp, int mntflags,
+ struct proc *p));
+
+/*
+ * Mount union filesystem
+ */
+static int
+union_mount(mp, path, data, ndp, p)
+ struct mount *mp;
+ char *path;
+ caddr_t data;
+ struct nameidata *ndp;
+ struct proc *p;
+{
+ int error = 0;
+ struct union_args args;
+ struct vnode *lowerrootvp = NULLVP;
+ struct vnode *upperrootvp = NULLVP;
+ struct union_mount *um = 0;
+ struct ucred *cred = 0;
+ 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. Vnode is stored in mp->mnt_vnodecovered.
+ * We need to reference it but not lock it.
+ */
+
+ lowerrootvp = mp->mnt_vnodecovered;
+ VREF(lowerrootvp);
+
+#if 0
+ /*
+ * Unlock lower node to avoid deadlock.
+ */
+ if (lowerrootvp->v_op == union_vnodeop_p)
+ VOP_UNLOCK(lowerrootvp, 0, p);
+#endif
+
+ /*
+ * Obtain upper vnode by calling namei() on the path. The
+ * upperrootvp will be turned referenced but not locked.
+ */
+ NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT,
+ UIO_USERSPACE, args.target, p);
+
+ error = namei(ndp);
+
+#if 0
+ if (lowerrootvp->v_op == union_vnodeop_p)
+ vn_lock(lowerrootvp, LK_EXCLUSIVE | LK_RETRY, p);
+#endif
+ if (error)
+ goto bad;
+
+ NDFREE(ndp, NDF_ONLY_PNBUF);
+ upperrootvp = ndp->ni_vp;
+ vrele(ndp->ni_dvp);
+ ndp->ni_dvp = NULL;
+
+ UDEBUG(("mount_root UPPERVP %p locked = %d\n", upperrootvp,
+ VOP_ISLOCKED(upperrootvp, NULL)));
+
+ /*
+ * 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
+ printf("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, LOOKUP);
+ if (error)
+ goto bad;
+ }
+
+ um->um_cred = p->p_ucred;
+ crhold(um->um_cred);
+ um->um_cmode = UN_DIRMODE &~ p->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);
+
+ (void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size);
+ bzero(mp->mnt_stat.f_mntonname + size, MNAMELEN - size);
+
+ 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);
+
+ (void)union_statfs(mp, &mp->mnt_stat, p);
+
+ UDEBUG(("union_mount: from %s, on %s\n",
+ mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname));
+ return (0);
+
+bad:
+ if (um) {
+ if (um->um_uppervp)
+ vrele(um->um_uppervp);
+ if (um->um_lowervp)
+ vrele(um->um_lowervp);
+ /* XXX other fields */
+ free(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(mp, mntflags, p)
+ struct mount *mp;
+ int mntflags;
+ struct proc *p;
+{
+ struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
+ struct vnode *um_rootvp;
+ int error;
+ int freeing;
+ int flags = 0;
+
+ UDEBUG(("union_unmount(mp = %p)\n", (void *)mp));
+
+ if (mntflags & MNT_FORCE)
+ flags |= FORCECLOSE;
+
+ if ((error = union_root(mp, &um_rootvp)) != 0)
+ return (error);
+
+ /*
+ * 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; vflush(mp, um_rootvp, flags) != 0;) {
+ struct vnode *vp;
+ int n;
+
+ /* count #vnodes held on mount list */
+ for (n = 0, vp = mp->mnt_vnodelist.lh_first;
+ vp != NULLVP;
+ vp = vp->v_mntvnodes.le_next)
+ n++;
+
+ /* if this is unchanged then stop */
+ if (n == freeing)
+ break;
+
+ /* otherwise try once more time */
+ freeing = n;
+ }
+
+ /* At this point the root vnode should have a single reference */
+ if (um_rootvp->v_usecount > 1) {
+ vput(um_rootvp);
+ return (EBUSY);
+ }
+
+#ifdef DEBUG
+ vprint("union root", um_rootvp);
+#endif
+ /*
+ * Discard references to upper and lower target vnodes.
+ */
+ if (um->um_lowervp)
+ vrele(um->um_lowervp);
+ vrele(um->um_uppervp);
+ crfree(um->um_cred);
+ /*
+ * Release reference on underlying root vnode
+ */
+ vput(um_rootvp);
+ /*
+ * And blow it away for future re-use
+ */
+ vgone(um_rootvp);
+ /*
+ * Finally, throw away the union_mount structure
+ */
+ free(mp->mnt_data, M_UNIONFSMNT); /* XXX */
+ mp->mnt_data = 0;
+ return (0);
+}
+
+static int
+union_root(mp, vpp)
+ 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,
+ VOP_ISLOCKED(um->um_uppervp, NULL)));
+
+ 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,
+ VOP_ISLOCKED(um->um_uppervp, NULL)));
+
+ return (error);
+}
+
+static int
+union_statfs(mp, sbp, p)
+ struct mount *mp;
+ struct statfs *sbp;
+ struct proc *p;
+{
+ 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, p);
+ 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, p);
+ 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_mntonname, sbp->f_mntonname, MNAMELEN);
+ bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN);
+ }
+ return (0);
+}
+
+static struct vfsops union_vfsops = {
+ union_mount,
+ vfs_stdstart, /* underlying start already done */
+ union_unmount,
+ union_root,
+ vfs_stdquotactl,
+ union_statfs,
+ vfs_stdsync, /* XXX assumes no cached data on union level */
+ vfs_stdvget,
+ vfs_stdfhtovp,
+ vfs_stdcheckexp,
+ vfs_stdvptofh,
+ union_init,
+ vfs_stduninit,
+ vfs_stdextattrctl,
+};
+
+VFS_SET(union_vfsops, union, VFCF_LOOPBACK);
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