freebsd-dev/sys/fs/unionfs/union_subr.c

1368 lines
32 KiB
C

/*
* Copyright (c) 1994 Jan-Simon Pendry
* Copyright (c) 1994
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed 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_subr.c 8.20 (Berkeley) 5/20/95
* $FreeBSD$
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/namei.h>
#include <sys/stat.h>
#include <sys/vnode.h>
#include <vm/vm.h>
#include <vm/vm_extern.h> /* for vnode_pager_setsize */
#include <vm/vm_object.h> /* for vm cache coherency */
#include <vm/uma.h>
#include <fs/unionfs/union.h>
#include <sys/proc.h>
extern int union_init(void);
/* must be power of two, otherwise change UNION_HASH() */
#define NHASH 32
/* unsigned int ... */
#define UNION_HASH(u, l) \
(((((uintptr_t) (u)) + ((uintptr_t) l)) >> 8) & (NHASH-1))
static LIST_HEAD(unhead, union_node) unhead[NHASH];
static int unvplock[NHASH];
static void union_dircache_r(struct vnode *vp, struct vnode ***vppp,
int *cntp);
static int union_list_lock(int ix);
static void union_list_unlock(int ix);
static int union_relookup(struct union_mount *um, struct vnode *dvp,
struct vnode **vpp,
struct componentname *cnp,
struct componentname *cn, char *path,
int pathlen);
static void union_updatevp(struct union_node *un,
struct vnode *uppervp,
struct vnode *lowervp);
static void union_newlower(struct union_node *, struct vnode *);
static void union_newupper(struct union_node *, struct vnode *);
static int union_copyfile(struct vnode *, struct vnode *,
struct ucred *, struct thread *);
static int union_vn_create(struct vnode **, struct union_node *,
struct thread *);
static int union_vn_close(struct vnode *, int, struct ucred *,
struct thread *);
int
union_init()
{
int i;
for (i = 0; i < NHASH; i++)
LIST_INIT(&unhead[i]);
bzero((caddr_t)unvplock, sizeof(unvplock));
return (0);
}
static int
union_list_lock(ix)
int ix;
{
if (unvplock[ix] & UNVP_LOCKED) {
unvplock[ix] |= UNVP_WANT;
(void) tsleep( &unvplock[ix], PINOD, "unllck", 0);
return (1);
}
unvplock[ix] |= UNVP_LOCKED;
return (0);
}
static void
union_list_unlock(ix)
int ix;
{
unvplock[ix] &= ~UNVP_LOCKED;
if (unvplock[ix] & UNVP_WANT) {
unvplock[ix] &= ~UNVP_WANT;
wakeup( &unvplock[ix]);
}
}
/*
* union_updatevp:
*
* The uppervp, if not NULL, must be referenced and not locked by us
* The lowervp, if not NULL, must be referenced.
*
* If uppervp and lowervp match pointers already installed, then
* nothing happens. The passed vp's (when matching) are not adjusted.
*
* This routine may only be called by union_newupper() and
* union_newlower().
*/
static void
union_updatevp(un, uppervp, lowervp)
struct union_node *un;
struct vnode *uppervp;
struct vnode *lowervp;
{
int ohash = UNION_HASH(un->un_uppervp, un->un_lowervp);
int nhash = UNION_HASH(uppervp, lowervp);
int docache = (lowervp != NULLVP || uppervp != NULLVP);
int lhash, uhash;
/*
* Ensure locking is ordered from lower to higher
* to avoid deadlocks.
*/
if (nhash < ohash) {
lhash = nhash;
uhash = ohash;
} else {
lhash = ohash;
uhash = nhash;
}
if (lhash != uhash) {
while (union_list_lock(lhash))
continue;
}
while (union_list_lock(uhash))
continue;
if (ohash != nhash || !docache) {
if (un->un_flags & UN_CACHED) {
un->un_flags &= ~UN_CACHED;
LIST_REMOVE(un, un_cache);
}
}
if (ohash != nhash)
union_list_unlock(ohash);
if (un->un_lowervp != lowervp) {
if (un->un_lowervp) {
vrele(un->un_lowervp);
if (un->un_path) {
free(un->un_path, M_TEMP);
un->un_path = 0;
}
}
un->un_lowervp = lowervp;
un->un_lowersz = VNOVAL;
}
if (un->un_uppervp != uppervp) {
if (un->un_uppervp)
vrele(un->un_uppervp);
un->un_uppervp = uppervp;
un->un_uppersz = VNOVAL;
}
if (docache && (ohash != nhash)) {
LIST_INSERT_HEAD(&unhead[nhash], un, un_cache);
un->un_flags |= UN_CACHED;
}
union_list_unlock(nhash);
}
/*
* Set a new lowervp. The passed lowervp must be referenced and will be
* stored in the vp in a referenced state.
*/
static void
union_newlower(un, lowervp)
struct union_node *un;
struct vnode *lowervp;
{
union_updatevp(un, un->un_uppervp, lowervp);
}
/*
* Set a new uppervp. The passed uppervp must be locked and will be
* stored in the vp in a locked state. The caller should not unlock
* uppervp.
*/
static void
union_newupper(un, uppervp)
struct union_node *un;
struct vnode *uppervp;
{
union_updatevp(un, uppervp, un->un_lowervp);
}
/*
* Keep track of size changes in the underlying vnodes.
* If the size changes, then callback to the vm layer
* giving priority to the upper layer size.
*/
void
union_newsize(vp, uppersz, lowersz)
struct vnode *vp;
off_t uppersz, lowersz;
{
struct union_node *un;
off_t sz;
/* only interested in regular files */
if (vp->v_type != VREG)
return;
un = VTOUNION(vp);
sz = VNOVAL;
if ((uppersz != VNOVAL) && (un->un_uppersz != uppersz)) {
un->un_uppersz = uppersz;
if (sz == VNOVAL)
sz = un->un_uppersz;
}
if ((lowersz != VNOVAL) && (un->un_lowersz != lowersz)) {
un->un_lowersz = lowersz;
if (sz == VNOVAL)
sz = un->un_lowersz;
}
if (sz != VNOVAL) {
UDEBUG(("union: %s size now %ld\n",
(uppersz != VNOVAL ? "upper" : "lower"), (long)sz));
/*
* There is no need to change size of non-existent object.
*/
/* vnode_pager_setsize(vp, sz); */
}
}
/*
* union_allocvp: allocate a union_node and associate it with a
* parent union_node and one or two vnodes.
*
* vpp Holds the returned vnode locked and referenced if no
* error occurs.
*
* mp Holds the mount point. mp may or may not be busied.
* allocvp() makes no changes to mp.
*
* dvp Holds the parent union_node to the one we wish to create.
* XXX may only be used to traverse an uncopied lowervp-based
* tree? XXX
*
* dvp may or may not be locked. allocvp() makes no changes
* to dvp.
*
* upperdvp Holds the parent vnode to uppervp, generally used along
* with path component information to create a shadow of
* lowervp when uppervp does not exist.
*
* upperdvp is referenced but unlocked on entry, and will be
* dereferenced on return.
*
* uppervp Holds the new uppervp vnode to be stored in the
* union_node we are allocating. uppervp is referenced but
* not locked, and will be dereferenced on return.
*
* lowervp Holds the new lowervp vnode to be stored in the
* union_node we are allocating. lowervp is referenced but
* not locked, and will be dereferenced on return.
*
* cnp Holds path component information to be coupled with
* lowervp and upperdvp to allow unionfs to create an uppervp
* later on. Only used if lowervp is valid. The contents
* of cnp is only valid for the duration of the call.
*
* docache Determine whether this node should be entered in the
* cache or whether it should be destroyed as soon as possible.
*
* All union_nodes are maintained on a singly-linked
* list. New nodes are only allocated when they cannot
* be found on this list. Entries on the list are
* removed when the vfs reclaim entry is called.
*
* A single lock is kept for the entire list. This is
* needed because the getnewvnode() function can block
* waiting for a vnode to become free, in which case there
* may be more than one process trying to get the same
* vnode. This lock is only taken if we are going to
* call getnewvnode(), since the kernel itself is single-threaded.
*
* If an entry is found on the list, then call vget() to
* take a reference. This is done because there may be
* zero references to it and so it needs to removed from
* the vnode free list.
*/
int
union_allocvp(vpp, mp, dvp, upperdvp, cnp, uppervp, lowervp, docache)
struct vnode **vpp;
struct mount *mp;
struct vnode *dvp; /* parent union vnode */
struct vnode *upperdvp; /* parent vnode of uppervp */
struct componentname *cnp; /* may be null */
struct vnode *uppervp; /* may be null */
struct vnode *lowervp; /* may be null */
int docache;
{
int error;
struct union_node *un = 0;
struct union_mount *um = MOUNTTOUNIONMOUNT(mp);
struct thread *td = (cnp) ? cnp->cn_thread : curthread;
int hash = 0;
int vflag;
int try;
if (uppervp == NULLVP && lowervp == NULLVP)
panic("union: unidentifiable allocation");
if (uppervp && lowervp && (uppervp->v_type != lowervp->v_type)) {
vrele(lowervp);
lowervp = NULLVP;
}
/* detect the root vnode (and aliases) */
vflag = 0;
if ((uppervp == um->um_uppervp) &&
((lowervp == NULLVP) || lowervp == um->um_lowervp)) {
if (lowervp == NULLVP) {
lowervp = um->um_lowervp;
if (lowervp != NULLVP)
VREF(lowervp);
}
vflag = VV_ROOT;
}
loop:
if (!docache) {
un = 0;
} else for (try = 0; try < 3; try++) {
switch (try) {
case 0:
if (lowervp == NULLVP)
continue;
hash = UNION_HASH(uppervp, lowervp);
break;
case 1:
if (uppervp == NULLVP)
continue;
hash = UNION_HASH(uppervp, NULLVP);
break;
case 2:
if (lowervp == NULLVP)
continue;
hash = UNION_HASH(NULLVP, lowervp);
break;
}
while (union_list_lock(hash))
continue;
LIST_FOREACH(un, &unhead[hash], un_cache) {
if ((un->un_lowervp == lowervp ||
un->un_lowervp == NULLVP) &&
(un->un_uppervp == uppervp ||
un->un_uppervp == NULLVP) &&
(UNIONTOV(un)->v_mount == mp)) {
if (vget(UNIONTOV(un), 0,
cnp ? cnp->cn_thread : NULL)) {
union_list_unlock(hash);
goto loop;
}
break;
}
}
union_list_unlock(hash);
if (un)
break;
}
if (un) {
/*
* Obtain a lock on the union_node. Everything is unlocked
* except for dvp, so check that case. If they match, our
* new un is already locked. Otherwise we have to lock our
* new un.
*
* A potential deadlock situation occurs when we are holding
* one lock while trying to get another. We must follow
* strict ordering rules to avoid it. We try to locate dvp
* by scanning up from un_vnode, since the most likely
* scenario is un being under dvp.
*/
if (dvp && un->un_vnode != dvp) {
struct vnode *scan = un->un_vnode;
do {
scan = VTOUNION(scan)->un_pvp;
} while (scan && scan->v_op == union_vnodeop_p &&
scan != dvp);
if (scan != dvp) {
/*
* our new un is above dvp (we never saw dvp
* while moving up the tree).
*/
VREF(dvp);
VOP_UNLOCK(dvp, 0, td);
error = vn_lock(un->un_vnode, LK_EXCLUSIVE, td);
vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY, td);
vrele(dvp);
} else {
/*
* our new un is under dvp
*/
error = vn_lock(un->un_vnode, LK_EXCLUSIVE, td);
}
} else if (dvp == NULLVP) {
/*
* dvp is NULL, we need to lock un.
*/
error = vn_lock(un->un_vnode, LK_EXCLUSIVE, td);
} else {
/*
* dvp == un->un_vnode, we are already locked.
*/
error = 0;
}
if (error)
goto loop;
/*
* At this point, the union_node is locked and referenced.
*
* uppervp is locked and referenced or NULL, lowervp is
* referenced or NULL.
*/
UDEBUG(("Modify existing un %p vn %p upper %p(refs %d) -> %p(refs %d)\n",
un, un->un_vnode, un->un_uppervp,
(un->un_uppervp ? vrefcnt(un->un_uppervp) : -99),
uppervp,
(uppervp ? vrefcnt(uppervp) : -99)
));
if (uppervp != un->un_uppervp) {
KASSERT(uppervp == NULL || vrefcnt(uppervp) > 0, ("union_allocvp: too few refs %d (at least 1 required) on uppervp", vrefcnt(uppervp)));
union_newupper(un, uppervp);
} else if (uppervp) {
KASSERT(vrefcnt(uppervp) > 1, ("union_allocvp: too few refs %d (at least 2 required) on uppervp", vrefcnt(uppervp)));
vrele(uppervp);
}
/*
* Save information about the lower layer.
* This needs to keep track of pathname
* and directory information which union_vn_create()
* might need.
*/
if (lowervp != un->un_lowervp) {
union_newlower(un, lowervp);
if (cnp && (lowervp != NULLVP)) {
un->un_path = malloc(cnp->cn_namelen+1,
M_TEMP, M_WAITOK);
bcopy(cnp->cn_nameptr, un->un_path,
cnp->cn_namelen);
un->un_path[cnp->cn_namelen] = '\0';
}
} else if (lowervp) {
vrele(lowervp);
}
/*
* and upperdvp
*/
if (upperdvp != un->un_dirvp) {
if (un->un_dirvp)
vrele(un->un_dirvp);
un->un_dirvp = upperdvp;
} else if (upperdvp) {
vrele(upperdvp);
}
*vpp = UNIONTOV(un);
return (0);
}
if (docache) {
/*
* Otherwise lock the vp list while we call getnewvnode()
* since that can block.
*/
hash = UNION_HASH(uppervp, lowervp);
if (union_list_lock(hash))
goto loop;
}
/*
* Create new node rather than replace old node.
*/
error = getnewvnode("union", mp, union_vnodeop_p, vpp);
if (error) {
/*
* If an error occurs, clear out vnodes.
*/
if (lowervp)
vrele(lowervp);
if (uppervp)
vrele(uppervp);
if (upperdvp)
vrele(upperdvp);
*vpp = NULL;
goto out;
}
MALLOC((*vpp)->v_data, void *, sizeof(struct union_node),
M_TEMP, M_WAITOK);
ASSERT_VOP_LOCKED(*vpp, "union_allocvp");
(*vpp)->v_vflag |= vflag;
if (uppervp)
(*vpp)->v_type = uppervp->v_type;
else
(*vpp)->v_type = lowervp->v_type;
un = VTOUNION(*vpp);
bzero(un, sizeof(*un));
vn_lock(*vpp, LK_EXCLUSIVE | LK_RETRY, td);
un->un_vnode = *vpp;
un->un_uppervp = uppervp;
un->un_uppersz = VNOVAL;
un->un_lowervp = lowervp;
un->un_lowersz = VNOVAL;
un->un_dirvp = upperdvp;
un->un_pvp = dvp; /* only parent dir in new allocation */
if (dvp != NULLVP)
VREF(dvp);
un->un_dircache = 0;
un->un_openl = 0;
if (cnp && (lowervp != NULLVP)) {
un->un_path = malloc(cnp->cn_namelen+1, M_TEMP, M_WAITOK);
bcopy(cnp->cn_nameptr, un->un_path, cnp->cn_namelen);
un->un_path[cnp->cn_namelen] = '\0';
} else {
un->un_path = 0;
un->un_dirvp = NULL;
}
if (docache) {
LIST_INSERT_HEAD(&unhead[hash], un, un_cache);
un->un_flags |= UN_CACHED;
}
out:
if (docache)
union_list_unlock(hash);
return (error);
}
int
union_freevp(vp)
struct vnode *vp;
{
struct union_node *un = VTOUNION(vp);
if (un->un_flags & UN_CACHED) {
un->un_flags &= ~UN_CACHED;
LIST_REMOVE(un, un_cache);
}
if (un->un_pvp != NULLVP) {
vrele(un->un_pvp);
un->un_pvp = NULL;
}
if (un->un_uppervp != NULLVP) {
vrele(un->un_uppervp);
un->un_uppervp = NULL;
}
if (un->un_lowervp != NULLVP) {
vrele(un->un_lowervp);
un->un_lowervp = NULL;
}
if (un->un_dirvp != NULLVP) {
vrele(un->un_dirvp);
un->un_dirvp = NULL;
}
if (un->un_path) {
free(un->un_path, M_TEMP);
un->un_path = NULL;
}
FREE(vp->v_data, M_TEMP);
vp->v_data = 0;
return (0);
}
/*
* copyfile. Copy the vnode (fvp) to the vnode (tvp)
* using a sequence of reads and writes. Both (fvp)
* and (tvp) are locked on entry and exit.
*
* fvp and tvp are both exclusive locked on call, but their refcount's
* haven't been bumped at all.
*/
static int
union_copyfile(fvp, tvp, cred, td)
struct vnode *fvp;
struct vnode *tvp;
struct ucred *cred;
struct thread *td;
{
char *buf;
struct uio uio;
struct iovec iov;
int error = 0;
/*
* strategy:
* Allocate a buffer of size MAXBSIZE.
* Loop doing reads and writes, keeping track
* of the current uio offset.
* Give up at the first sign of trouble.
*/
bzero(&uio, sizeof(uio));
uio.uio_td = td;
uio.uio_segflg = UIO_SYSSPACE;
uio.uio_offset = 0;
VOP_LEASE(fvp, td, cred, LEASE_READ);
VOP_LEASE(tvp, td, cred, LEASE_WRITE);
buf = malloc(MAXBSIZE, M_TEMP, M_WAITOK);
/* ugly loop follows... */
do {
off_t offset = uio.uio_offset;
int count;
int bufoffset;
/*
* Setup for big read.
*/
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
iov.iov_base = buf;
iov.iov_len = MAXBSIZE;
uio.uio_resid = iov.iov_len;
uio.uio_rw = UIO_READ;
if ((error = VOP_READ(fvp, &uio, 0, cred)) != 0)
break;
/*
* Get bytes read, handle read eof case and setup for
* write loop.
*/
if ((count = MAXBSIZE - uio.uio_resid) == 0)
break;
bufoffset = 0;
/*
* Write until an error occurs or our buffer has been
* exhausted, then update the offset for the next read.
*/
while (bufoffset < count) {
uio.uio_iov = &iov;
uio.uio_iovcnt = 1;
iov.iov_base = buf + bufoffset;
iov.iov_len = count - bufoffset;
uio.uio_offset = offset + bufoffset;
uio.uio_rw = UIO_WRITE;
uio.uio_resid = iov.iov_len;
if ((error = VOP_WRITE(tvp, &uio, 0, cred)) != 0)
break;
bufoffset += (count - bufoffset) - uio.uio_resid;
}
uio.uio_offset = offset + bufoffset;
} while (error == 0);
free(buf, M_TEMP);
return (error);
}
/*
*
* un's vnode is assumed to be locked on entry and remains locked on exit.
*/
int
union_copyup(un, docopy, cred, td)
struct union_node *un;
int docopy;
struct ucred *cred;
struct thread *td;
{
int error;
struct mount *mp;
struct vnode *lvp, *uvp;
/*
* If the user does not have read permission, the vnode should not
* be copied to upper layer.
*/
vn_lock(un->un_lowervp, LK_EXCLUSIVE | LK_RETRY, td);
error = VOP_ACCESS(un->un_lowervp, VREAD, cred, td);
VOP_UNLOCK(un->un_lowervp, 0, td);
if (error)
return (error);
if ((error = vn_start_write(un->un_dirvp, &mp, V_WAIT | PCATCH)) != 0)
return (error);
if ((error = union_vn_create(&uvp, un, td)) != 0) {
vn_finished_write(mp);
return (error);
}
lvp = un->un_lowervp;
KASSERT(vrefcnt(uvp) > 0, ("copy: uvp refcount 0: %d", vrefcnt(uvp)));
if (docopy) {
/*
* XX - should not ignore errors
* from VOP_CLOSE()
*/
vn_lock(lvp, LK_EXCLUSIVE | LK_RETRY, td);
error = VOP_OPEN(lvp, FREAD, cred, td);
if (error == 0 && vn_canvmio(lvp) == TRUE)
error = vfs_object_create(lvp, td, cred);
if (error == 0) {
error = union_copyfile(lvp, uvp, cred, td);
VOP_UNLOCK(lvp, 0, td);
(void) VOP_CLOSE(lvp, FREAD, cred, td);
}
if (error == 0)
UDEBUG(("union: copied up %s\n", un->un_path));
}
VOP_UNLOCK(uvp, 0, td);
vn_finished_write(mp);
union_newupper(un, uvp);
KASSERT(vrefcnt(uvp) > 0, ("copy: uvp refcount 0: %d", vrefcnt(uvp)));
union_vn_close(uvp, FWRITE, cred, td);
KASSERT(vrefcnt(uvp) > 0, ("copy: uvp refcount 0: %d", vrefcnt(uvp)));
/*
* Subsequent IOs will go to the top layer, so
* call close on the lower vnode and open on the
* upper vnode to ensure that the filesystem keeps
* its references counts right. This doesn't do
* the right thing with (cred) and (FREAD) though.
* Ignoring error returns is not right, either.
*/
if (error == 0) {
int i;
for (i = 0; i < un->un_openl; i++) {
(void) VOP_CLOSE(lvp, FREAD, cred, td);
(void) VOP_OPEN(uvp, FREAD, cred, td);
}
if (un->un_openl) {
if (vn_canvmio(uvp) == TRUE)
error = vfs_object_create(uvp, td, cred);
}
un->un_openl = 0;
}
return (error);
}
/*
* union_relookup:
*
* dvp should be locked on entry and will be locked on return. No
* net change in the ref count will occur.
*
* If an error is returned, *vpp will be invalid, otherwise it
* will hold a locked, referenced vnode. If *vpp == dvp then
* remember that only one exclusive lock is held.
*/
static int
union_relookup(um, dvp, vpp, cnp, cn, path, pathlen)
struct union_mount *um;
struct vnode *dvp;
struct vnode **vpp;
struct componentname *cnp;
struct componentname *cn;
char *path;
int pathlen;
{
int error;
/*
* A new componentname structure must be faked up because
* there is no way to know where the upper level cnp came
* from or what it is being used for. This must duplicate
* some of the work done by NDINIT(), some of the work done
* by namei(), some of the work done by lookup() and some of
* the work done by VOP_LOOKUP() when given a CREATE flag.
* Conclusion: Horrible.
*/
cn->cn_namelen = pathlen;
cn->cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
bcopy(path, cn->cn_pnbuf, cn->cn_namelen);
cn->cn_pnbuf[cn->cn_namelen] = '\0';
cn->cn_nameiop = CREATE;
cn->cn_flags = (LOCKPARENT|LOCKLEAF|HASBUF|SAVENAME|ISLASTCN);
cn->cn_thread = cnp->cn_thread;
if (um->um_op == UNMNT_ABOVE)
cn->cn_cred = cnp->cn_cred;
else
cn->cn_cred = um->um_cred;
cn->cn_nameptr = cn->cn_pnbuf;
cn->cn_consume = cnp->cn_consume;
VREF(dvp);
VOP_UNLOCK(dvp, 0, cnp->cn_thread);
/*
* Pass dvp unlocked and referenced on call to relookup().
*
* If an error occurs, dvp will be returned unlocked and dereferenced.
*/
if ((error = relookup(dvp, vpp, cn)) != 0) {
vn_lock(dvp, LK_EXCLUSIVE | LK_RETRY, cnp->cn_thread);
return(error);
}
/*
* If no error occurs, dvp will be returned locked with the reference
* left as before, and vpp will be returned referenced and locked.
*
* We want to return with dvp as it was passed to us, so we get
* rid of our reference.
*/
vrele(dvp);
return (0);
}
/*
* Create a shadow directory in the upper layer.
* The new vnode is returned locked.
*
* (um) points to the union mount structure for access to the
* the mounting process's credentials.
* (dvp) is the directory in which to create the shadow directory,
* It is locked (but not ref'd) on entry and return.
* (cnp) is the component name to be created.
* (vpp) is the returned newly created shadow directory, which
* is returned locked and ref'd
*/
int
union_mkshadow(um, dvp, cnp, vpp)
struct union_mount *um;
struct vnode *dvp;
struct componentname *cnp;
struct vnode **vpp;
{
int error;
struct vattr va;
struct thread *td = cnp->cn_thread;
struct componentname cn;
struct mount *mp;
if ((error = vn_start_write(dvp, &mp, V_WAIT | PCATCH)) != 0)
return (error);
if ((error = union_relookup(um, dvp, vpp, cnp, &cn,
cnp->cn_nameptr, cnp->cn_namelen)) != 0) {
vn_finished_write(mp);
return (error);
}
if (*vpp) {
if (cn.cn_flags & HASBUF) {
uma_zfree(namei_zone, cn.cn_pnbuf);
cn.cn_flags &= ~HASBUF;
}
if (dvp == *vpp)
vrele(*vpp);
else
vput(*vpp);
vn_finished_write(mp);
*vpp = NULLVP;
return (EEXIST);
}
/*
* Policy: when creating the shadow directory in the
* upper layer, create it owned by the user who did
* the mount, group from parent directory, and mode
* 777 modified by umask (ie mostly identical to the
* mkdir syscall). (jsp, kb)
*/
VATTR_NULL(&va);
va.va_type = VDIR;
va.va_mode = um->um_cmode;
/* VOP_LEASE: dvp is locked */
VOP_LEASE(dvp, td, cn.cn_cred, LEASE_WRITE);
error = VOP_MKDIR(dvp, vpp, &cn, &va);
if (cn.cn_flags & HASBUF) {
uma_zfree(namei_zone, cn.cn_pnbuf);
cn.cn_flags &= ~HASBUF;
}
/*vput(dvp);*/
vn_finished_write(mp);
return (error);
}
/*
* Create a whiteout entry in the upper layer.
*
* (um) points to the union mount structure for access to the
* the mounting process's credentials.
* (dvp) is the directory in which to create the whiteout.
* It is locked on entry and return.
* (cnp) is the component name to be created.
*/
int
union_mkwhiteout(um, dvp, cnp, path)
struct union_mount *um;
struct vnode *dvp;
struct componentname *cnp;
char *path;
{
int error;
struct thread *td = cnp->cn_thread;
struct vnode *wvp;
struct componentname cn;
struct mount *mp;
if ((error = vn_start_write(dvp, &mp, V_WAIT | PCATCH)) != 0)
return (error);
error = union_relookup(um, dvp, &wvp, cnp, &cn, path, strlen(path));
if (error) {
vn_finished_write(mp);
return (error);
}
if (wvp) {
if (cn.cn_flags & HASBUF) {
uma_zfree(namei_zone, cn.cn_pnbuf);
cn.cn_flags &= ~HASBUF;
}
if (wvp == dvp)
vrele(wvp);
else
vput(wvp);
vn_finished_write(mp);
return (EEXIST);
}
/* VOP_LEASE: dvp is locked */
VOP_LEASE(dvp, td, td->td_ucred, LEASE_WRITE);
error = VOP_WHITEOUT(dvp, &cn, CREATE);
if (cn.cn_flags & HASBUF) {
uma_zfree(namei_zone, cn.cn_pnbuf);
cn.cn_flags &= ~HASBUF;
}
vn_finished_write(mp);
return (error);
}
/*
* union_vn_create: creates and opens a new shadow file
* on the upper union layer. This function is similar
* in spirit to calling vn_open() but it avoids calling namei().
* The problem with calling namei() is that a) it locks too many
* things, and b) it doesn't start at the "right" directory,
* whereas relookup() is told where to start.
*
* On entry, the vnode associated with un is locked. It remains locked
* on return.
*
* If no error occurs, *vpp contains a locked referenced vnode for your
* use. If an error occurs *vpp iis undefined.
*/
static int
union_vn_create(vpp, un, td)
struct vnode **vpp;
struct union_node *un;
struct thread *td;
{
struct vnode *vp;
struct ucred *cred = td->td_ucred;
struct vattr vat;
struct vattr *vap = &vat;
int fmode = FFLAGS(O_WRONLY|O_CREAT|O_TRUNC|O_EXCL);
int error;
int cmode;
struct componentname cn;
*vpp = NULLVP;
FILEDESC_LOCK(td->td_proc->p_fd);
cmode = UN_FILEMODE & ~td->td_proc->p_fd->fd_cmask;
FILEDESC_UNLOCK(td->td_proc->p_fd);
/*
* Build a new componentname structure (for the same
* reasons outlines in union_mkshadow()).
* The difference here is that the file is owned by
* the current user, rather than by the person who
* did the mount, since the current user needs to be
* able to write the file (that's why it is being
* copied in the first place).
*/
cn.cn_namelen = strlen(un->un_path);
cn.cn_pnbuf = uma_zalloc(namei_zone, M_WAITOK);
bcopy(un->un_path, cn.cn_pnbuf, cn.cn_namelen+1);
cn.cn_nameiop = CREATE;
cn.cn_flags = (LOCKPARENT|LOCKLEAF|HASBUF|SAVENAME|ISLASTCN);
cn.cn_thread = td;
cn.cn_cred = td->td_ucred;
cn.cn_nameptr = cn.cn_pnbuf;
cn.cn_consume = 0;
/*
* Pass dvp unlocked and referenced on call to relookup().
*
* If an error occurs, dvp will be returned unlocked and dereferenced.
*/
VREF(un->un_dirvp);
error = relookup(un->un_dirvp, &vp, &cn);
if (error)
return (error);
/*
* If no error occurs, dvp will be returned locked with the reference
* left as before, and vpp will be returned referenced and locked.
*/
if (vp) {
vput(un->un_dirvp);
if (cn.cn_flags & HASBUF) {
uma_zfree(namei_zone, cn.cn_pnbuf);
cn.cn_flags &= ~HASBUF;
}
if (vp == un->un_dirvp)
vrele(vp);
else
vput(vp);
return (EEXIST);
}
/*
* Good - there was no race to create the file
* so go ahead and create it. The permissions
* on the file will be 0666 modified by the
* current user's umask. Access to the file, while
* it is unioned, will require access to the top *and*
* bottom files. Access when not unioned will simply
* require access to the top-level file.
* TODO: confirm choice of access permissions.
*/
VATTR_NULL(vap);
vap->va_type = VREG;
vap->va_mode = cmode;
VOP_LEASE(un->un_dirvp, td, cred, LEASE_WRITE);
error = VOP_CREATE(un->un_dirvp, &vp, &cn, vap);
if (cn.cn_flags & HASBUF) {
uma_zfree(namei_zone, cn.cn_pnbuf);
cn.cn_flags &= ~HASBUF;
}
vput(un->un_dirvp);
if (error)
return (error);
error = VOP_OPEN(vp, fmode, cred, td);
if (error == 0 && vn_canvmio(vp) == TRUE)
error = vfs_object_create(vp, td, cred);
if (error) {
vput(vp);
return (error);
}
vp->v_writecount++;
*vpp = vp;
return (0);
}
static int
union_vn_close(vp, fmode, cred, td)
struct vnode *vp;
int fmode;
struct ucred *cred;
struct thread *td;
{
if (fmode & FWRITE)
--vp->v_writecount;
return (VOP_CLOSE(vp, fmode, cred, td));
}
#if 0
/*
* union_removed_upper:
*
* called with union_node unlocked. XXX
*/
void
union_removed_upper(un)
struct union_node *un;
{
struct thread *td = curthread; /* XXX */
struct vnode **vpp;
/*
* Do not set the uppervp to NULLVP. If lowervp is NULLVP,
* union node will have neither uppervp nor lowervp. We remove
* the union node from cache, so that it will not be referrenced.
*/
union_newupper(un, NULLVP);
if (un->un_dircache != 0) {
for (vpp = un->un_dircache; *vpp != NULLVP; vpp++)
vrele(*vpp);
free(un->un_dircache, M_TEMP);
un->un_dircache = 0;
}
if (un->un_flags & UN_CACHED) {
un->un_flags &= ~UN_CACHED;
LIST_REMOVE(un, un_cache);
}
}
#endif
/*
* Determine whether a whiteout is needed
* during a remove/rmdir operation.
*/
int
union_dowhiteout(un, cred, td)
struct union_node *un;
struct ucred *cred;
struct thread *td;
{
struct vattr va;
if (un->un_lowervp != NULLVP)
return (1);
if (VOP_GETATTR(un->un_uppervp, &va, cred, td) == 0 &&
(va.va_flags & OPAQUE))
return (1);
return (0);
}
static void
union_dircache_r(vp, vppp, cntp)
struct vnode *vp;
struct vnode ***vppp;
int *cntp;
{
struct union_node *un;
if (vp->v_op != union_vnodeop_p) {
if (vppp) {
VREF(vp);
*(*vppp)++ = vp;
if (--(*cntp) == 0)
panic("union: dircache table too small");
} else {
(*cntp)++;
}
return;
}
un = VTOUNION(vp);
if (un->un_uppervp != NULLVP)
union_dircache_r(un->un_uppervp, vppp, cntp);
if (un->un_lowervp != NULLVP)
union_dircache_r(un->un_lowervp, vppp, cntp);
}
struct vnode *
union_dircache(vp, td)
struct vnode *vp;
struct thread *td;
{
int cnt;
struct vnode *nvp;
struct vnode **vpp;
struct vnode **dircache;
struct union_node *un;
int error;
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
dircache = VTOUNION(vp)->un_dircache;
nvp = NULLVP;
if (dircache == NULL) {
cnt = 0;
union_dircache_r(vp, 0, &cnt);
cnt++;
dircache = malloc(cnt * sizeof(struct vnode *),
M_TEMP, M_WAITOK);
vpp = dircache;
union_dircache_r(vp, &vpp, &cnt);
*vpp = NULLVP;
vpp = dircache + 1;
} else {
vpp = dircache;
do {
if (*vpp++ == VTOUNION(vp)->un_uppervp)
break;
} while (*vpp != NULLVP);
}
if (*vpp == NULLVP)
goto out;
/*vn_lock(*vpp, LK_EXCLUSIVE | LK_RETRY, td);*/
UDEBUG(("ALLOCVP-3 %p ref %d\n", *vpp, (*vpp ? vrefcnt(*vpp) : -99)));
VREF(*vpp);
error = union_allocvp(&nvp, vp->v_mount, NULLVP, NULLVP, NULL, *vpp, NULLVP, 0);
UDEBUG(("ALLOCVP-3B %p ref %d\n", nvp, (*vpp ? vrefcnt(*vpp) : -99)));
if (error)
goto out;
VTOUNION(vp)->un_dircache = 0;
un = VTOUNION(nvp);
un->un_dircache = dircache;
out:
VOP_UNLOCK(vp, 0, td);
return (nvp);
}
/*
* Module glue to remove #ifdef UNION from vfs_syscalls.c
*/
static int
union_dircheck(struct thread *td, struct vnode **vp, struct file *fp)
{
int error = 0;
if ((*vp)->v_op == union_vnodeop_p) {
struct vnode *lvp;
lvp = union_dircache(*vp, td);
if (lvp != NULLVP) {
struct vattr va;
/*
* If the directory is opaque,
* then don't show lower entries
*/
error = VOP_GETATTR(*vp, &va, fp->f_cred, td);
if (va.va_flags & OPAQUE) {
vput(lvp);
lvp = NULL;
}
}
if (lvp != NULLVP) {
error = VOP_OPEN(lvp, FREAD, fp->f_cred, td);
if (error == 0 && vn_canvmio(lvp) == TRUE)
error = vfs_object_create(lvp, td, fp->f_cred);
if (error) {
vput(lvp);
return (error);
}
VOP_UNLOCK(lvp, 0, td);
FILE_LOCK(fp);
fp->f_data = lvp;
fp->f_offset = 0;
FILE_UNLOCK(fp);
error = vn_close(*vp, FREAD, fp->f_cred, td);
if (error)
return (error);
*vp = lvp;
return -1; /* goto unionread */
}
}
return error;
}
static int
union_modevent(module_t mod, int type, void *data)
{
switch (type) {
case MOD_LOAD:
union_dircheckp = union_dircheck;
break;
case MOD_UNLOAD:
union_dircheckp = NULL;
break;
default:
break;
}
return 0;
}
static moduledata_t union_mod = {
"union_dircheck",
union_modevent,
NULL
};
DECLARE_MODULE(union_dircheck, union_mod, SI_SUB_VFS, SI_ORDER_ANY);