/* $NetBSD: union_vfsops.c,v 1.88 2024/05/18 00:04:46 thorpej Exp $ */
/*
* Copyright (c) 1994 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.
*
* @(#)union_vfsops.c 8.20 (Berkeley) 5/20/95
*/
/*
* Copyright (c) 1994 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
*/
/*
* Union Layer
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: union_vfsops.c,v 1.88 2024/05/18 00:04:46 thorpej Exp $");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysctl.h>
#include <sys/time.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/filedesc.h>
#include <sys/queue.h>
#include <sys/stat.h>
#include <sys/kauth.h>
#include <sys/module.h>
#include <miscfs/genfs/genfs.h>
#include <fs/union/union.h>
MODULE(MODULE_CLASS_VFS, union, NULL);
/*
* Mount union filesystem
*/
int
union_mount(struct mount *mp, const char *path, void *data, size_t *data_len)
{
struct lwp *l = curlwp;
int error = 0;
struct union_args *args = data;
struct vnode *lowerrootvp = NULLVP;
struct vnode *upperrootvp = NULLVP;
struct union_mount *um = 0;
const char *cp;
char *xp;
int len;
size_t size;
if (args == NULL)
return EINVAL;
if (*data_len < sizeof *args)
return EINVAL;
#ifdef UNION_DIAGNOSTIC
printf("%s(mp = %p)\n", __func__, mp);
#endif
if (mp->mnt_flag & MNT_GETARGS) {
um = MOUNTTOUNIONMOUNT(mp);
if (um == NULL)
return EIO;
args->target = NULL;
args->mntflags = um->um_op;
*data_len = sizeof *args;
return 0;
}
/*
* 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;
}
lowerrootvp = mp->mnt_vnodecovered;
vref(lowerrootvp);
/*
* Find upper node.
*/
error = namei_simple_user(args->target,
NSM_FOLLOW_NOEMULROOT, &upperrootvp);
if (error != 0)
goto bad;
if (upperrootvp->v_type != VDIR) {
error = EINVAL;
goto bad;
}
um = kmem_zalloc(sizeof(*um), KM_SLEEP);
/*
* Keep a held reference to the target vnodes.
* They are vrele'd in union_unmount.
*
* 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->um_op = args->mntflags & UNMNT_OPMASK;
switch (um->um_op) {
case UNMNT_ABOVE:
um->um_lowervp = lowerrootvp;
um->um_uppervp = upperrootvp;
break;
case UNMNT_BELOW:
um->um_lowervp = upperrootvp;
um->um_uppervp = lowerrootvp;
break;
case UNMNT_REPLACE:
vrele(lowerrootvp);
lowerrootvp = NULLVP;
um->um_uppervp = upperrootvp;
um->um_lowervp = lowerrootvp;
break;
default:
error = EINVAL;
goto bad;
}
/*
* This mount is mp-safe if both lower mounts are mp-safe.
*/
if (((um->um_lowervp == NULLVP) ||
(um->um_lowervp->v_mount->mnt_iflag & IMNT_MPSAFE)) &&
(um->um_uppervp->v_mount->mnt_iflag & IMNT_MPSAFE))
mp->mnt_iflag |= IMNT_MPSAFE;
/*
* Unless the mount is readonly, ensure that the top layer
* supports whiteout operations
*/
if ((mp->mnt_flag & MNT_RDONLY) == 0) {
static struct componentname nullcn = {
.cn_nameiop = LOOKUP,
.cn_cred = NOCRED
};
vn_lock(um->um_uppervp, LK_EXCLUSIVE | LK_RETRY);
error = VOP_WHITEOUT(um->um_uppervp, &nullcn, LOOKUP);
VOP_UNLOCK(um->um_uppervp);
if (error)
goto bad;
}
um->um_cred = l->l_cred;
kauth_cred_hold(um->um_cred);
um->um_cmode = UN_DIRMODE &~ l->l_proc->p_cwdi->cwdi_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 = um;
vfs_getnewfsid(mp);
error = set_statvfs_info(path, UIO_USERSPACE, NULL, UIO_USERSPACE,
mp->mnt_op->vfs_name, mp, l);
if (error)
goto bad;
error = vfs_set_lowermount(mp, um->um_uppervp->v_mount);
if (error)
goto bad;
switch (um->um_op) {
case UNMNT_ABOVE:
cp = "<above>:";
break;
case UNMNT_BELOW:
cp = "<below>:";
break;
case UNMNT_REPLACE:
cp = "";
break;
default:
cp = "<invalid>:";
#ifdef DIAGNOSTIC
panic("%s: bad um_op", __func__);
#endif
break;
}
len = strlen(cp);
memcpy(mp->mnt_stat.f_mntfromname, cp, len);
xp = mp->mnt_stat.f_mntfromname + len;
len = MNAMELEN - len;
(void) copyinstr(args->target, xp, len - 1, &size);
memset(xp + size, 0, len - size);
#ifdef UNION_DIAGNOSTIC
printf("%s: from %s, on %s\n", __func__,
mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname);
#endif
/* Setup the readdir hook if it's not set already */
if (!vn_union_readdir_hook)
vn_union_readdir_hook = union_readdirhook;
return 0;
bad:
if (um) {
if (um->um_cred)
kauth_cred_free(um->um_cred);
kmem_free(um, sizeof(*um));
}
if (upperrootvp)
vrele(upperrootvp);
if (lowerrootvp)
vrele(lowerrootvp);
return error;
}
/*
* VFS start. Nothing needed here - the start routine
* on the underlying filesystem(s) will have been called
* when that filesystem was mounted.
*/
/*ARGSUSED*/
int
union_start(struct mount *mp, int flags)
{
return 0;
}
/*
* Free reference to union layer
*/
static bool
union_unmount_selector(void *cl, struct vnode *vp)
{
int *count = cl;
KASSERT(mutex_owned(vp->v_interlock));
*count += 1;
return false;
}
int
union_unmount(struct mount *mp, int mntflags)
{
struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
int freeing;
int error;
#ifdef UNION_DIAGNOSTIC
printf("%s(mp = %p)\n", __func__, mp);
#endif
/*
* 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, NULL, 0)) != 0;) {
struct vnode_iterator *marker;
int n;
/* count #vnodes held on mount list */
n = 0;
vfs_vnode_iterator_init(mp, &marker);
vfs_vnode_iterator_next(marker, union_unmount_selector, &n);
vfs_vnode_iterator_destroy(marker);
/* if this is unchanged then stop */
if (n == freeing)
break;
/* otherwise try once more time */
freeing = n;
}
/*
* Ok, now that we've tried doing it gently, get out the hammer.
*/
if (mntflags & MNT_FORCE)
error = vflush(mp, NULL, FORCECLOSE);
if (error)
return error;
/*
* Discard references to upper and lower target vnodes.
*/
if (um->um_lowervp)
vrele(um->um_lowervp);
vrele(um->um_uppervp);
kauth_cred_free(um->um_cred);
/*
* Finally, throw away the union_mount structure
*/
kmem_free(um, sizeof(*um));
mp->mnt_data = NULL;
return 0;
}
int
union_root(struct mount *mp, int lktype, struct vnode **vpp)
{
struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
int error;
/*
* Return locked reference to root.
*/
vref(um->um_uppervp);
if (um->um_lowervp)
vref(um->um_lowervp);
error = union_allocvp(vpp, mp, NULL, NULL, NULL,
um->um_uppervp, um->um_lowervp, 1);
if (error) {
vrele(um->um_uppervp);
if (um->um_lowervp)
vrele(um->um_lowervp);
return error;
}
vn_lock(*vpp, lktype | LK_RETRY);
return 0;
}
int
union_statvfs(struct mount *mp, struct statvfs *sbp)
{
int error;
struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
struct statvfs *sbuf = kmem_zalloc(sizeof(*sbuf), KM_SLEEP);
unsigned long lbsize;
#ifdef UNION_DIAGNOSTIC
printf("%s(mp = %p, lvp = %p, uvp = %p)\n", __func__, mp,
um->um_lowervp, um->um_uppervp);
#endif
if (um->um_lowervp) {
error = VFS_STATVFS(um->um_lowervp->v_mount, sbuf);
if (error)
goto done;
}
/* now copy across the "interesting" information and fake the rest */
lbsize = sbuf->f_bsize;
sbp->f_blocks = sbuf->f_blocks - sbuf->f_bfree;
sbp->f_files = sbuf->f_files - sbuf->f_ffree;
error = VFS_STATVFS(um->um_uppervp->v_mount, sbuf);
if (error)
goto done;
sbp->f_flag = sbuf->f_flag;
sbp->f_bsize = sbuf->f_bsize;
sbp->f_frsize = sbuf->f_frsize;
sbp->f_iosize = sbuf->f_iosize;
/*
* 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 writable).
*/
if (sbuf->f_bsize != lbsize)
sbp->f_blocks = sbp->f_blocks * lbsize / sbuf->f_bsize;
sbp->f_blocks += sbuf->f_blocks;
sbp->f_bfree = sbuf->f_bfree;
sbp->f_bavail = sbuf->f_bavail;
sbp->f_bresvd = sbuf->f_bresvd;
sbp->f_files += sbuf->f_files;
sbp->f_ffree = sbuf->f_ffree;
sbp->f_favail = sbuf->f_favail;
sbp->f_fresvd = sbuf->f_fresvd;
copy_statvfs_info(sbp, mp);
done:
kmem_free(sbuf, sizeof(*sbuf));
return error;
}
/*ARGSUSED*/
int
union_sync(struct mount *mp, int waitfor, kauth_cred_t cred)
{
/*
* XXX - Assumes no data cached at union layer.
*/
return 0;
}
/*ARGSUSED*/
int
union_vget(struct mount *mp, ino_t ino, int lktype, struct vnode **vpp)
{
return EOPNOTSUPP;
}
static int
union_renamelock_enter(struct mount *mp)
{
struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
/* Lock just the upper fs, where the action happens. */
return VFS_RENAMELOCK_ENTER(um->um_uppervp->v_mount);
}
static void
union_renamelock_exit(struct mount *mp)
{
struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
VFS_RENAMELOCK_EXIT(um->um_uppervp->v_mount);
}
extern const struct vnodeopv_desc union_vnodeop_opv_desc;
const struct vnodeopv_desc * const union_vnodeopv_descs[] = {
&union_vnodeop_opv_desc,
NULL,
};
struct vfsops union_vfsops = {
.vfs_name = MOUNT_UNION,
.vfs_min_mount_data = sizeof (struct union_args),
.vfs_mount = union_mount,
.vfs_start = union_start,
.vfs_unmount = union_unmount,
.vfs_root = union_root,
.vfs_quotactl = (void *)eopnotsupp,
.vfs_statvfs = union_statvfs,
.vfs_sync = union_sync,
.vfs_vget = union_vget,
.vfs_loadvnode = union_loadvnode,
.vfs_fhtovp = (void *)eopnotsupp,
.vfs_vptofh = (void *)eopnotsupp,
.vfs_init = union_init,
.vfs_reinit = union_reinit,
.vfs_done = union_done,
.vfs_snapshot = (void *)eopnotsupp,
.vfs_extattrctl = vfs_stdextattrctl,
.vfs_suspendctl = genfs_suspendctl,
.vfs_renamelock_enter = union_renamelock_enter,
.vfs_renamelock_exit = union_renamelock_exit,
.vfs_fsync = (void *)eopnotsupp,
.vfs_opv_descs = union_vnodeopv_descs
};
SYSCTL_SETUP(unionfs_sysctl_setup, "unionfs sysctl")
{
sysctl_createv(clog, 0, NULL, NULL,
CTLFLAG_PERMANENT,
CTLTYPE_NODE, "union",
SYSCTL_DESCR("Union file system"),
NULL, 0, NULL, 0,
CTL_VFS, 15, CTL_EOL);
/*
* XXX the "15" above could be dynamic, thereby eliminating
* one more instance of the "number to vfs" mapping problem,
* but "15" is the order as taken from sys/mount.h
*/
}
static int
union_modcmd(modcmd_t cmd, void *arg)
{
switch (cmd) {
case MODULE_CMD_INIT:
return vfs_attach(&union_vfsops);
case MODULE_CMD_FINI:
return vfs_detach(&union_vfsops);
default:
return ENOTTY;
}
}
