491 lines
13 KiB
C
491 lines
13 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1992, 1993, 1995
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software donated to Berkeley by
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* Jan-Simon Pendry.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94
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*
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* @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92
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*/
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/*
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* Null Layer
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* (See null_vnops.c for a description of what this does.)
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/fcntl.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mount.h>
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#include <sys/namei.h>
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#include <sys/proc.h>
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#include <sys/vnode.h>
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#include <sys/jail.h>
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#include <fs/nullfs/null.h>
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static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure");
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static vfs_fhtovp_t nullfs_fhtovp;
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static vfs_mount_t nullfs_mount;
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static vfs_quotactl_t nullfs_quotactl;
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static vfs_root_t nullfs_root;
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static vfs_sync_t nullfs_sync;
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static vfs_statfs_t nullfs_statfs;
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static vfs_unmount_t nullfs_unmount;
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static vfs_vget_t nullfs_vget;
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static vfs_extattrctl_t nullfs_extattrctl;
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/*
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* Mount null layer
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*/
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static int
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nullfs_mount(struct mount *mp)
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{
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struct vnode *lowerrootvp;
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struct vnode *nullm_rootvp;
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struct null_mount *xmp;
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struct null_node *nn;
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struct nameidata nd, *ndp;
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char *target;
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int error, len;
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bool isvnunlocked;
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NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
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if (mp->mnt_flag & MNT_ROOTFS)
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return (EOPNOTSUPP);
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/*
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* Update is a no-op
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*/
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if (mp->mnt_flag & MNT_UPDATE) {
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/*
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* Only support update mounts for NFS export.
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*/
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if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0))
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return (0);
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else
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return (EOPNOTSUPP);
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}
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/*
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* Get argument
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*/
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error = vfs_getopt(mp->mnt_optnew, "from", (void **)&target, &len);
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if (error != 0)
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error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len);
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if (error || target[len - 1] != '\0')
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return (EINVAL);
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/*
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* Unlock lower node to avoid possible deadlock.
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*/
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if (mp->mnt_vnodecovered->v_op == &null_vnodeops &&
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VOP_ISLOCKED(mp->mnt_vnodecovered) == LK_EXCLUSIVE) {
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VOP_UNLOCK(mp->mnt_vnodecovered);
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isvnunlocked = true;
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} else {
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isvnunlocked = false;
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}
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/*
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* Find lower node
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*/
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ndp = &nd;
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NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target);
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error = namei(ndp);
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/*
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* Re-lock vnode.
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* XXXKIB This is deadlock-prone as well.
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*/
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if (isvnunlocked)
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vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY);
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if (error)
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return (error);
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NDFREE_PNBUF(ndp);
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/*
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* Sanity check on lower vnode
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*/
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lowerrootvp = ndp->ni_vp;
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/*
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* Check multi null mount to avoid `lock against myself' panic.
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*/
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if (mp->mnt_vnodecovered->v_op == &null_vnodeops) {
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nn = VTONULL(mp->mnt_vnodecovered);
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if (nn == NULL || lowerrootvp == nn->null_lowervp) {
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NULLFSDEBUG("nullfs_mount: multi null mount?\n");
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vput(lowerrootvp);
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return (EDEADLK);
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}
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}
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/*
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* Lower vnode must be the same type as the covered vnode - we
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* don't allow mounting directories to files or vice versa.
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*/
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if ((lowerrootvp->v_type != VDIR && lowerrootvp->v_type != VREG) ||
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lowerrootvp->v_type != mp->mnt_vnodecovered->v_type) {
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NULLFSDEBUG("nullfs_mount: target must be same type as fspath");
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vput(lowerrootvp);
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return (EINVAL);
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}
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xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
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M_NULLFSMNT, M_WAITOK | M_ZERO);
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/*
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* Save pointer to underlying FS and the reference to the
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* lower root vnode.
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*/
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xmp->nullm_vfs = vfs_register_upper_from_vp(lowerrootvp, mp,
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&xmp->upper_node);
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if (xmp->nullm_vfs == NULL) {
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vput(lowerrootvp);
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free(xmp, M_NULLFSMNT);
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return (ENOENT);
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}
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vref(lowerrootvp);
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xmp->nullm_lowerrootvp = lowerrootvp;
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mp->mnt_data = xmp;
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/*
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* Make sure the node alias worked.
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*/
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error = null_nodeget(mp, lowerrootvp, &nullm_rootvp);
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if (error != 0) {
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vfs_unregister_upper(xmp->nullm_vfs, &xmp->upper_node);
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vrele(lowerrootvp);
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free(xmp, M_NULLFSMNT);
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return (error);
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}
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if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) {
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MNT_ILOCK(mp);
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mp->mnt_flag |= MNT_LOCAL;
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MNT_IUNLOCK(mp);
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}
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xmp->nullm_flags |= NULLM_CACHE;
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if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0 ||
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(xmp->nullm_vfs->mnt_kern_flag & MNTK_NULL_NOCACHE) != 0)
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xmp->nullm_flags &= ~NULLM_CACHE;
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if ((xmp->nullm_flags & NULLM_CACHE) != 0) {
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vfs_register_for_notification(xmp->nullm_vfs, mp,
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&xmp->notify_node);
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}
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if (lowerrootvp == mp->mnt_vnodecovered) {
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vn_lock(lowerrootvp, LK_EXCLUSIVE | LK_RETRY | LK_CANRECURSE);
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lowerrootvp->v_vflag |= VV_CROSSLOCK;
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VOP_UNLOCK(lowerrootvp);
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}
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MNT_ILOCK(mp);
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if ((xmp->nullm_flags & NULLM_CACHE) != 0) {
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mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag &
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(MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED |
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MNTK_EXTENDED_SHARED);
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}
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mp->mnt_kern_flag |= MNTK_NOMSYNC | MNTK_UNLOCKED_INSMNTQUE;
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mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag &
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(MNTK_USES_BCACHE | MNTK_NO_IOPF | MNTK_UNMAPPED_BUFS);
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MNT_IUNLOCK(mp);
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vfs_getnewfsid(mp);
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vfs_mountedfrom(mp, target);
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vput(nullm_rootvp);
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NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
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mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
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return (0);
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}
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/*
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* Free reference to null layer
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*/
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static int
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nullfs_unmount(struct mount *mp, int mntflags)
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{
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struct null_mount *mntdata;
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int error, flags;
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NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
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if (mntflags & MNT_FORCE)
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flags = FORCECLOSE;
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else
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flags = 0;
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for (;;) {
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/* There is 1 extra root vnode reference (nullm_rootvp). */
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error = vflush(mp, 0, flags, curthread);
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if (error)
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return (error);
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MNT_ILOCK(mp);
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if (mp->mnt_nvnodelistsize == 0) {
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MNT_IUNLOCK(mp);
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break;
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}
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MNT_IUNLOCK(mp);
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if ((mntflags & MNT_FORCE) == 0)
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return (EBUSY);
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}
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/*
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* Finally, throw away the null_mount structure
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*/
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mntdata = mp->mnt_data;
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if ((mntdata->nullm_flags & NULLM_CACHE) != 0) {
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vfs_unregister_for_notification(mntdata->nullm_vfs,
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&mntdata->notify_node);
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}
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if (mntdata->nullm_lowerrootvp == mp->mnt_vnodecovered) {
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vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY | LK_CANRECURSE);
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mp->mnt_vnodecovered->v_vflag &= ~VV_CROSSLOCK;
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VOP_UNLOCK(mp->mnt_vnodecovered);
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}
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vfs_unregister_upper(mntdata->nullm_vfs, &mntdata->upper_node);
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vrele(mntdata->nullm_lowerrootvp);
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mp->mnt_data = NULL;
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free(mntdata, M_NULLFSMNT);
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return (0);
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}
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static int
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nullfs_root(struct mount *mp, int flags, struct vnode **vpp)
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{
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struct vnode *vp;
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struct null_mount *mntdata;
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int error;
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mntdata = MOUNTTONULLMOUNT(mp);
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NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", mp,
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mntdata->nullm_lowerrootvp);
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error = vget(mntdata->nullm_lowerrootvp, flags);
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if (error == 0) {
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error = null_nodeget(mp, mntdata->nullm_lowerrootvp, &vp);
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if (error == 0) {
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*vpp = vp;
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}
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}
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return (error);
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}
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static int
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nullfs_quotactl(struct mount *mp, int cmd, uid_t uid, void *arg, bool *mp_busy)
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{
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struct mount *lowermp;
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struct null_mount *mntdata;
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int error;
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bool unbusy;
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mntdata = MOUNTTONULLMOUNT(mp);
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lowermp = atomic_load_ptr(&mntdata->nullm_vfs);
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KASSERT(*mp_busy == true, ("upper mount not busy"));
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/*
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* See comment in sys_quotactl() for an explanation of why the
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* lower mount needs to be busied by the caller of VFS_QUOTACTL()
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* but may be unbusied by the implementation. We must unbusy
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* the upper mount for the same reason; otherwise a namei lookup
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* issued by the VFS_QUOTACTL() implementation could traverse the
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* upper mount and deadlock.
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*/
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vfs_unbusy(mp);
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*mp_busy = false;
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unbusy = true;
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error = vfs_busy(lowermp, 0);
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if (error == 0)
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error = VFS_QUOTACTL(lowermp, cmd, uid, arg, &unbusy);
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if (unbusy)
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vfs_unbusy(lowermp);
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return (error);
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}
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static int
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nullfs_statfs(struct mount *mp, struct statfs *sbp)
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{
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int error;
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struct statfs *mstat;
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NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp,
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(void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
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(void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
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mstat = malloc(sizeof(struct statfs), M_STATFS, M_WAITOK | M_ZERO);
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error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, mstat);
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if (error) {
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free(mstat, M_STATFS);
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return (error);
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}
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/* now copy across the "interesting" information and fake the rest */
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sbp->f_type = mstat->f_type;
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sbp->f_flags = (sbp->f_flags & (MNT_RDONLY | MNT_NOEXEC | MNT_NOSUID |
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MNT_UNION | MNT_NOSYMFOLLOW | MNT_AUTOMOUNTED)) |
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(mstat->f_flags & ~(MNT_ROOTFS | MNT_AUTOMOUNTED));
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sbp->f_bsize = mstat->f_bsize;
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sbp->f_iosize = mstat->f_iosize;
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sbp->f_blocks = mstat->f_blocks;
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sbp->f_bfree = mstat->f_bfree;
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sbp->f_bavail = mstat->f_bavail;
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sbp->f_files = mstat->f_files;
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sbp->f_ffree = mstat->f_ffree;
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free(mstat, M_STATFS);
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return (0);
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}
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static int
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nullfs_sync(struct mount *mp, int waitfor)
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{
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/*
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* XXX - Assumes no data cached at null layer.
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*/
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return (0);
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}
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static int
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nullfs_vget(struct mount *mp, ino_t ino, int flags, struct vnode **vpp)
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{
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int error;
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KASSERT((flags & LK_TYPE_MASK) != 0,
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("nullfs_vget: no lock requested"));
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error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp);
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if (error != 0)
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return (error);
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return (null_nodeget(mp, *vpp, vpp));
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}
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static int
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nullfs_fhtovp(struct mount *mp, struct fid *fidp, int flags, struct vnode **vpp)
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{
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int error;
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error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, flags,
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vpp);
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if (error != 0)
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return (error);
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return (null_nodeget(mp, *vpp, vpp));
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}
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static int
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nullfs_extattrctl(struct mount *mp, int cmd, struct vnode *filename_vp,
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int namespace, const char *attrname)
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{
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return (VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd,
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filename_vp, namespace, attrname));
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}
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static void
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nullfs_reclaim_lowervp(struct mount *mp, struct vnode *lowervp)
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{
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struct vnode *vp;
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vp = null_hashget(mp, lowervp);
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if (vp == NULL)
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return;
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VTONULL(vp)->null_flags |= NULLV_NOUNLOCK;
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vgone(vp);
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vput(vp);
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}
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static void
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nullfs_unlink_lowervp(struct mount *mp, struct vnode *lowervp)
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{
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struct vnode *vp;
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struct null_node *xp;
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vp = null_hashget(mp, lowervp);
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if (vp == NULL)
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return;
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xp = VTONULL(vp);
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xp->null_flags |= NULLV_DROP | NULLV_NOUNLOCK;
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vhold(vp);
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vunref(vp);
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if (vp->v_usecount == 0) {
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/*
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* If vunref() dropped the last use reference on the
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* nullfs vnode, it must be reclaimed, and its lock
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* was split from the lower vnode lock. Need to do
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* extra unlock before allowing the final vdrop() to
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* free the vnode.
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*/
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KASSERT(VN_IS_DOOMED(vp),
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("not reclaimed nullfs vnode %p", vp));
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VOP_UNLOCK(vp);
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} else {
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/*
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* Otherwise, the nullfs vnode still shares the lock
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* with the lower vnode, and must not be unlocked.
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* Also clear the NULLV_NOUNLOCK, the flag is not
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* relevant for future reclamations.
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*/
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ASSERT_VOP_ELOCKED(vp, "unlink_lowervp");
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KASSERT(!VN_IS_DOOMED(vp),
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("reclaimed nullfs vnode %p", vp));
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xp->null_flags &= ~NULLV_NOUNLOCK;
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}
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vdrop(vp);
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}
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static struct vfsops null_vfsops = {
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.vfs_extattrctl = nullfs_extattrctl,
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.vfs_fhtovp = nullfs_fhtovp,
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.vfs_init = nullfs_init,
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.vfs_mount = nullfs_mount,
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.vfs_quotactl = nullfs_quotactl,
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.vfs_root = nullfs_root,
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.vfs_statfs = nullfs_statfs,
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.vfs_sync = nullfs_sync,
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.vfs_uninit = nullfs_uninit,
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.vfs_unmount = nullfs_unmount,
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.vfs_vget = nullfs_vget,
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.vfs_reclaim_lowervp = nullfs_reclaim_lowervp,
|
|
.vfs_unlink_lowervp = nullfs_unlink_lowervp,
|
|
};
|
|
|
|
VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL | VFCF_FILEMOUNT);
|