/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1992, 1993, 1995
* The Regents of the University of California. 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. 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.
*
* @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94
*
* @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92
* $FreeBSD$
*/
/*
* Null Layer
* (See null_vnops.c for a description of what this does.)
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/fcntl.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/jail.h>
#include <fs/nullfs/null.h>
static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure");
static vfs_fhtovp_t nullfs_fhtovp;
static vfs_mount_t nullfs_mount;
static vfs_quotactl_t nullfs_quotactl;
static vfs_root_t nullfs_root;
static vfs_sync_t nullfs_sync;
static vfs_statfs_t nullfs_statfs;
static vfs_unmount_t nullfs_unmount;
static vfs_vget_t nullfs_vget;
static vfs_extattrctl_t nullfs_extattrctl;
/*
* Mount null layer
*/
static int
nullfs_mount(struct mount *mp)
{
struct vnode *lowerrootvp;
struct vnode *nullm_rootvp;
struct null_mount *xmp;
struct null_node *nn;
struct nameidata nd, *ndp;
char *target;
int error, len;
bool isvnunlocked;
NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp);
if (mp->mnt_flag & MNT_ROOTFS)
return (EOPNOTSUPP);
/*
* Update is a no-op
*/
if (mp->mnt_flag & MNT_UPDATE) {
/*
* Only support update mounts for NFS export.
*/
if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0))
return (0);
else
return (EOPNOTSUPP);
}
/*
* Get argument
*/
error = vfs_getopt(mp->mnt_optnew, "from", (void **)&target, &len);
if (error != 0)
error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len);
if (error || target[len - 1] != '\0')
return (EINVAL);
/*
* Unlock lower node to avoid possible deadlock.
*/
if (mp->mnt_vnodecovered->v_op == &null_vnodeops &&
VOP_ISLOCKED(mp->mnt_vnodecovered) == LK_EXCLUSIVE) {
VOP_UNLOCK(mp->mnt_vnodecovered);
isvnunlocked = true;
} else {
isvnunlocked = false;
}
/*
* Find lower node
*/
ndp = &nd;
NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, curthread);
error = namei(ndp);
/*
* Re-lock vnode.
* XXXKIB This is deadlock-prone as well.
*/
if (isvnunlocked)
vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY);
if (error)
return (error);
NDFREE(ndp, NDF_ONLY_PNBUF);
/*
* Sanity check on lower vnode
*/
lowerrootvp = ndp->ni_vp;
/*
* Check multi null mount to avoid `lock against myself' panic.
*/
if (mp->mnt_vnodecovered->v_op == &null_vnodeops) {
nn = VTONULL(mp->mnt_vnodecovered);
if (nn == NULL || lowerrootvp == nn->null_lowervp) {
NULLFSDEBUG("nullfs_mount: multi null mount?\n");
vput(lowerrootvp);
return (EDEADLK);
}
}
xmp = (struct null_mount *) malloc(sizeof(struct null_mount),
M_NULLFSMNT, M_WAITOK | M_ZERO);
/*
* Save pointer to underlying FS and the reference to the
* lower root vnode.
*/
xmp->nullm_vfs = vfs_pin_from_vp(lowerrootvp);
if (xmp->nullm_vfs == NULL) {
vput(lowerrootvp);
free(xmp, M_NULLFSMNT);
return (ENOENT);
}
vref(lowerrootvp);
xmp->nullm_lowerrootvp = lowerrootvp;
mp->mnt_data = xmp;
/*
* Make sure the node alias worked.
*/
error = null_nodeget(mp, lowerrootvp, &nullm_rootvp);
if (error != 0) {
vfs_unpin(xmp->nullm_vfs);
vrele(lowerrootvp);
free(xmp, M_NULLFSMNT);
return (error);
}
if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) {
MNT_ILOCK(mp);
mp->mnt_flag |= MNT_LOCAL;
MNT_IUNLOCK(mp);
}
xmp->nullm_flags |= NULLM_CACHE;
if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0 ||
(xmp->nullm_vfs->mnt_kern_flag & MNTK_NULL_NOCACHE) != 0)
xmp->nullm_flags &= ~NULLM_CACHE;
MNT_ILOCK(mp);
if ((xmp->nullm_flags & NULLM_CACHE) != 0) {
mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag &
(MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED |
MNTK_EXTENDED_SHARED);
}
mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT | MNTK_NOMSYNC;
mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag &
(MNTK_USES_BCACHE | MNTK_NO_IOPF | MNTK_UNMAPPED_BUFS);
MNT_IUNLOCK(mp);
vfs_getnewfsid(mp);
if ((xmp->nullm_flags & NULLM_CACHE) != 0) {
MNT_ILOCK(xmp->nullm_vfs);
TAILQ_INSERT_TAIL(&xmp->nullm_vfs->mnt_uppers, mp,
mnt_upper_link);
MNT_IUNLOCK(xmp->nullm_vfs);
}
vfs_mountedfrom(mp, target);
vput(nullm_rootvp);
NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n",
mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
return (0);
}
/*
* Free reference to null layer
*/
static int
nullfs_unmount(mp, mntflags)
struct mount *mp;
int mntflags;
{
struct null_mount *mntdata;
struct mount *ump;
int error, flags;
NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp);
if (mntflags & MNT_FORCE)
flags = FORCECLOSE;
else
flags = 0;
for (;;) {
/* There is 1 extra root vnode reference (nullm_rootvp). */
error = vflush(mp, 0, flags, curthread);
if (error)
return (error);
MNT_ILOCK(mp);
if (mp->mnt_nvnodelistsize == 0) {
MNT_IUNLOCK(mp);
break;
}
MNT_IUNLOCK(mp);
if ((mntflags & MNT_FORCE) == 0)
return (EBUSY);
}
/*
* Finally, throw away the null_mount structure
*/
mntdata = mp->mnt_data;
ump = mntdata->nullm_vfs;
if ((mntdata->nullm_flags & NULLM_CACHE) != 0) {
MNT_ILOCK(ump);
while ((ump->mnt_kern_flag & MNTK_VGONE_UPPER) != 0) {
ump->mnt_kern_flag |= MNTK_VGONE_WAITER;
msleep(&ump->mnt_uppers, &ump->mnt_mtx, 0, "vgnupw", 0);
}
TAILQ_REMOVE(&ump->mnt_uppers, mp, mnt_upper_link);
MNT_IUNLOCK(ump);
}
vfs_unpin(ump);
vrele(mntdata->nullm_lowerrootvp);
mp->mnt_data = NULL;
free(mntdata, M_NULLFSMNT);
return (0);
}
static int
nullfs_root(mp, flags, vpp)
struct mount *mp;
int flags;
struct vnode **vpp;
{
struct vnode *vp;
struct null_mount *mntdata;
int error;
mntdata = MOUNTTONULLMOUNT(mp);
NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", mp,
mntdata->nullm_lowerrootvp);
error = vget(mntdata->nullm_lowerrootvp, flags);
if (error == 0) {
error = null_nodeget(mp, mntdata->nullm_lowerrootvp, &vp);
if (error == 0) {
*vpp = vp;
}
}
return (error);
}
static int
nullfs_quotactl(mp, cmd, uid, arg, mp_busy)
struct mount *mp;
int cmd;
uid_t uid;
void *arg;
bool *mp_busy;
{
struct mount *lowermp;
struct null_mount *mntdata;
int error;
bool unbusy;
mntdata = MOUNTTONULLMOUNT(mp);
lowermp = atomic_load_ptr(&mntdata->nullm_vfs);
KASSERT(*mp_busy == true, ("upper mount not busy"));
/*
* See comment in sys_quotactl() for an explanation of why the
* lower mount needs to be busied by the caller of VFS_QUOTACTL()
* but may be unbusied by the implementation. We must unbusy
* the upper mount for the same reason; otherwise a namei lookup
* issued by the VFS_QUOTACTL() implementation could traverse the
* upper mount and deadlock.
*/
vfs_unbusy(mp);
*mp_busy = false;
unbusy = true;
error = vfs_busy(lowermp, 0);
if (error == 0)
error = VFS_QUOTACTL(lowermp, cmd, uid, arg, &unbusy);
if (unbusy)
vfs_unbusy(lowermp);
return (error);
}
static int
nullfs_statfs(mp, sbp)
struct mount *mp;
struct statfs *sbp;
{
int error;
struct statfs *mstat;
NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp,
(void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp,
(void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp));
mstat = malloc(sizeof(struct statfs), M_STATFS, M_WAITOK | M_ZERO);
error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, mstat);
if (error) {
free(mstat, M_STATFS);
return (error);
}
/* now copy across the "interesting" information and fake the rest */
sbp->f_type = mstat->f_type;
sbp->f_flags = (sbp->f_flags & (MNT_RDONLY | MNT_NOEXEC | MNT_NOSUID |
MNT_UNION | MNT_NOSYMFOLLOW | MNT_AUTOMOUNTED)) |
(mstat->f_flags & ~(MNT_ROOTFS | MNT_AUTOMOUNTED));
sbp->f_bsize = mstat->f_bsize;
sbp->f_iosize = mstat->f_iosize;
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;
free(mstat, M_STATFS);
return (0);
}
static int
nullfs_sync(mp, waitfor)
struct mount *mp;
int waitfor;
{
/*
* XXX - Assumes no data cached at null layer.
*/
return (0);
}
static int
nullfs_vget(mp, ino, flags, vpp)
struct mount *mp;
ino_t ino;
int flags;
struct vnode **vpp;
{
int error;
KASSERT((flags & LK_TYPE_MASK) != 0,
("nullfs_vget: no lock requested"));
error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp);
if (error != 0)
return (error);
return (null_nodeget(mp, *vpp, vpp));
}
static int
nullfs_fhtovp(mp, fidp, flags, vpp)
struct mount *mp;
struct fid *fidp;
int flags;
struct vnode **vpp;
{
int error;
error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, flags,
vpp);
if (error != 0)
return (error);
return (null_nodeget(mp, *vpp, vpp));
}
static int
nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname)
struct mount *mp;
int cmd;
struct vnode *filename_vp;
int namespace;
const char *attrname;
{
return (VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd,
filename_vp, namespace, attrname));
}
static void
nullfs_reclaim_lowervp(struct mount *mp, struct vnode *lowervp)
{
struct vnode *vp;
vp = null_hashget(mp, lowervp);
if (vp == NULL)
return;
VTONULL(vp)->null_flags |= NULLV_NOUNLOCK;
vgone(vp);
vput(vp);
}
static void
nullfs_unlink_lowervp(struct mount *mp, struct vnode *lowervp)
{
struct vnode *vp;
struct null_node *xp;
vp = null_hashget(mp, lowervp);
if (vp == NULL)
return;
xp = VTONULL(vp);
xp->null_flags |= NULLV_DROP | NULLV_NOUNLOCK;
vhold(vp);
vunref(vp);
if (vp->v_usecount == 0) {
/*
* If vunref() dropped the last use reference on the
* nullfs vnode, it must be reclaimed, and its lock
* was split from the lower vnode lock. Need to do
* extra unlock before allowing the final vdrop() to
* free the vnode.
*/
KASSERT(VN_IS_DOOMED(vp),
("not reclaimed nullfs vnode %p", vp));
VOP_UNLOCK(vp);
} else {
/*
* Otherwise, the nullfs vnode still shares the lock
* with the lower vnode, and must not be unlocked.
* Also clear the NULLV_NOUNLOCK, the flag is not
* relevant for future reclamations.
*/
ASSERT_VOP_ELOCKED(vp, "unlink_lowervp");
KASSERT(!VN_IS_DOOMED(vp),
("reclaimed nullfs vnode %p", vp));
xp->null_flags &= ~NULLV_NOUNLOCK;
}
vdrop(vp);
}
static struct vfsops null_vfsops = {
.vfs_extattrctl = nullfs_extattrctl,
.vfs_fhtovp = nullfs_fhtovp,
.vfs_init = nullfs_init,
.vfs_mount = nullfs_mount,
.vfs_quotactl = nullfs_quotactl,
.vfs_root = nullfs_root,
.vfs_statfs = nullfs_statfs,
.vfs_sync = nullfs_sync,
.vfs_uninit = nullfs_uninit,
.vfs_unmount = nullfs_unmount,
.vfs_vget = nullfs_vget,
.vfs_reclaim_lowervp = nullfs_reclaim_lowervp,
.vfs_unlink_lowervp = nullfs_unlink_lowervp,
};
VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL);
