freebsd-dev/sys/fs/unionfs/union_vfsops.c
2003-11-01 15:04:50 +00:00

499 lines
13 KiB
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
* $FreeBSD$
*/
/*
* Union Layer
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.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 <fs/unionfs/union.h>
static MALLOC_DEFINE(M_UNIONFSMNT, "UNION mount", "UNION mount structure");
extern vfs_init_t union_init;
static vfs_root_t union_root;
static vfs_nmount_t union_mount;
static vfs_statfs_t union_statfs;
static vfs_unmount_t union_unmount;
/*
* Mount union filesystem.
*/
static int
union_mount(mp, ndp, td)
struct mount *mp;
struct nameidata *ndp;
struct thread *td;
{
int error = 0;
struct vfsoptlist *opts;
struct vnode *lowerrootvp = NULLVP;
struct vnode *upperrootvp = NULLVP;
struct union_mount *um = 0;
struct ucred *cred = 0;
char *cp = 0, *target;
int op;
int len;
size_t size;
struct componentname fakecn;
UDEBUG(("union_mount(mp = %p)\n", (void *)mp));
opts = mp->mnt_optnew;
/*
* 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.
*/
return (EOPNOTSUPP);
/*
* Get arguments.
*/
error = vfs_getopt(opts, "target", (void **)&target, &len);
if (error || target[len - 1] != '\0')
return (EINVAL);
op = 0;
if (vfs_getopt(opts, "below", NULL, NULL) == 0)
op = UNMNT_BELOW;
if (vfs_getopt(opts, "replace", NULL, NULL) == 0) {
/* These options are mutually exclusive. */
if (op)
return (EINVAL);
op = UNMNT_REPLACE;
}
/*
* UNMNT_ABOVE is the default.
*/
if (op == 0)
op = UNMNT_ABOVE;
/*
* 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, td);
#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_SYSSPACE, target, td);
error = namei(ndp);
#if 0
if (lowerrootvp->v_op == union_vnodeop_p)
vn_lock(lowerrootvp, LK_EXCLUSIVE | LK_RETRY, td);
#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 | M_ZERO);
um->um_op = op;
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) {
/*
* XXX Fake up a struct componentname with only cn_nameiop
* and cn_thread valid; union_whiteout() needs to use the
* thread pointer to lock the vnode.
*/
bzero(&fakecn, sizeof(fakecn));
fakecn.cn_nameiop = LOOKUP;
fakecn.cn_thread = td;
error = VOP_WHITEOUT(um->um_uppervp, &fakecn, LOOKUP);
if (error)
goto bad;
}
um->um_cred = crhold(td->td_ucred);
FILEDESC_LOCK(td->td_proc->p_fd);
um->um_cmode = UN_DIRMODE &~ td->td_proc->p_fd->fd_cmask;
FILEDESC_UNLOCK(td->td_proc->p_fd);
/*
* 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) copystr(target, cp, len - 1, &size);
bzero(cp + size, len - size);
(void)union_statfs(mp, &mp->mnt_stat, td);
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, td)
struct mount *mp;
int mntflags;
struct thread *td;
{
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;
/* count #vnodes held on mount list */
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.
*/
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, td)
struct mount *mp;
struct statfs *sbp;
struct thread *td;
{
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, td);
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, td);
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 = {
.vfs_init = union_init,
.vfs_nmount = union_mount,
.vfs_root = union_root,
.vfs_statfs = union_statfs,
.vfs_unmount = union_unmount,
};
VFS_SET(union_vfsops, unionfs, VFCF_LOOPBACK);