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NetBSD/sys/miscfs/genfs/layer_vnops.c

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/* $NetBSD: layer_vnops.c,v 1.5 2000/12/21 03:51:02 enami Exp $ */
/*
* Copyright (c) 1999 National Aeronautics & Space Administration
* All rights reserved.
*
* This software was written by William Studenmund of the
* Numerical Aerospace Similation Facility, NASA Ames Research Center.
*
* 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 National Aeronautics & Space Administration
* 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 NATIONAL AERONAUTICS & SPACE ADMINISTRATION
* ``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 ADMINISTRATION OR CONTRIB-
* UTORS 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.
*/
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* John Heidemann of the UCLA Ficus project.
*
* 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.
*
* @(#)null_vnops.c 8.6 (Berkeley) 5/27/95
*
* Ancestors:
* @(#)lofs_vnops.c 1.2 (Berkeley) 6/18/92
* $Id: layer_vnops.c,v 1.5 2000/12/21 03:51:02 enami Exp $
* ...and...
* @(#)null_vnodeops.c 1.20 92/07/07 UCLA Ficus project
*/
/*
* Null Layer vnode routines.
*
* (See mount_null(8) for more information.)
*
* The layer.h, layer_extern.h, layer_vfs.c, and layer_vnops.c files provide
* the core implimentation of the null file system and most other stacked
* fs's. The description below refers to the null file system, but the
* services provided by the layer* files are useful for all layered fs's.
*
* The null layer duplicates a portion of the file system
* name space under a new name. In this respect, it is
* similar to the loopback file system. It differs from
* the loopback fs in two respects: it is implemented using
* a stackable layers techniques, and it's "null-node"s stack above
* all lower-layer vnodes, not just over directory vnodes.
*
* The null layer has two purposes. First, it serves as a demonstration
* of layering by proving a layer which does nothing. (It actually
* does everything the loopback file system does, which is slightly
* more than nothing.) Second, the null layer can serve as a prototype
* layer. Since it provides all necessary layer framework,
* new file system layers can be created very easily be starting
* with a null layer.
*
* The remainder of the man page examines the null layer as a basis
* for constructing new layers.
*
*
* INSTANTIATING NEW NULL LAYERS
*
* New null layers are created with mount_null(8).
* Mount_null(8) takes two arguments, the pathname
* of the lower vfs (target-pn) and the pathname where the null
* layer will appear in the namespace (alias-pn). After
* the null layer is put into place, the contents
* of target-pn subtree will be aliased under alias-pn.
*
* It is conceivable that other overlay filesystems will take different
* parameters. For instance, data migration or access controll layers might
* only take one pathname which will serve both as the target-pn and
* alias-pn described above.
*
*
* OPERATION OF A NULL LAYER
*
* The null layer is the minimum file system layer,
* simply bypassing all possible operations to the lower layer
* for processing there. The majority of its activity centers
* on the bypass routine, though which nearly all vnode operations
* pass.
*
* The bypass routine accepts arbitrary vnode operations for
* handling by the lower layer. It begins by examing vnode
* operation arguments and replacing any layered nodes by their
* lower-layer equivlants. It then invokes the operation
* on the lower layer. Finally, it replaces the layered nodes
* in the arguments and, if a vnode is return by the operation,
* stacks a layered node on top of the returned vnode.
*
* The bypass routine in this file, layer_bypass(), is suitable for use
* by many different layered filesystems. It can be used by multiple
* filesystems simultaneously. Alternatively, a layered fs may provide
* its own bypass routine, in which case layer_bypass() should be used as
* a model. For instance, the main functionality provided by umapfs, the user
* identity mapping file system, is handled by a custom bypass routine.
*
* Typically a layered fs registers its selected bypass routine as the
* default vnode operation in its vnodeopv_entry_desc table. Additionally
* the filesystem must store the bypass entry point in the layerm_bypass
* field of struct layer_mount. All other layer routines in this file will
* use the layerm_bypass routine.
*
* Although the bypass routine handles most operations outright, a number
* of operations are special cased, and handled by the layered fs. One
* group, layer_setattr, layer_getattr, layer_access, layer_open, and
* layer_fsync, perform layer-specific manipulation in addition to calling
* the bypass routine. The other group
* Although bypass handles most operations, vop_getattr, vop_lock,
* vop_unlock, vop_inactive, vop_reclaim, and vop_print are not
* bypassed. Vop_getattr must change the fsid being returned.
* Vop_lock and vop_unlock must handle any locking for the
* current vnode as well as pass the lock request down.
* Vop_inactive and vop_reclaim are not bypassed so that
* they can handle freeing null-layer specific data. Vop_print
* is not bypassed to avoid excessive debugging information.
* Also, certain vnode operations change the locking state within
* the operation (create, mknod, remove, link, rename, mkdir, rmdir,
* and symlink). Ideally these operations should not change the
* lock state, but should be changed to let the caller of the
* function unlock them. Otherwise all intermediate vnode layers
* (such as union, umapfs, etc) must catch these functions to do
* the necessary locking at their layer.
*
*
* INSTANTIATING VNODE STACKS
*
* Mounting associates the null layer with a lower layer,
* effect stacking two VFSes. Vnode stacks are instead
* created on demand as files are accessed.
*
* The initial mount creates a single vnode stack for the
* root of the new null layer. All other vnode stacks
* are created as a result of vnode operations on
* this or other null vnode stacks.
*
* New vnode stacks come into existance as a result of
* an operation which returns a vnode.
* The bypass routine stacks a null-node above the new
* vnode before returning it to the caller.
*
* For example, imagine mounting a null layer with
* "mount_null /usr/include /dev/layer/null".
* Changing directory to /dev/layer/null will assign
* the root null-node (which was created when the null layer was mounted).
* Now consider opening "sys". A vop_lookup would be
* done on the root null-node. This operation would bypass through
* to the lower layer which would return a vnode representing
* the UFS "sys". layer_bypass then builds a null-node
* aliasing the UFS "sys" and returns this to the caller.
* Later operations on the null-node "sys" will repeat this
* process when constructing other vnode stacks.
*
*
* CREATING OTHER FILE SYSTEM LAYERS
*
* One of the easiest ways to construct new file system layers is to make
* a copy of the null layer, rename all files and variables, and
* then begin modifing the copy. Sed can be used to easily rename
* all variables.
*
* The umap layer is an example of a layer descended from the
* null layer.
*
*
* INVOKING OPERATIONS ON LOWER LAYERS
*
* There are two techniques to invoke operations on a lower layer
* when the operation cannot be completely bypassed. Each method
* is appropriate in different situations. In both cases,
* it is the responsibility of the aliasing layer to make
* the operation arguments "correct" for the lower layer
* by mapping an vnode arguments to the lower layer.
*
* The first approach is to call the aliasing layer's bypass routine.
* This method is most suitable when you wish to invoke the operation
* currently being hanldled on the lower layer. It has the advantage
* that the bypass routine already must do argument mapping.
* An example of this is null_getattrs in the null layer.
*
* A second approach is to directly invoked vnode operations on
* the lower layer with the VOP_OPERATIONNAME interface.
* The advantage of this method is that it is easy to invoke
* arbitrary operations on the lower layer. The disadvantage
* is that vnodes arguments must be manualy mapped.
*
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/namei.h>
#include <sys/malloc.h>
#include <sys/buf.h>
#include <miscfs/genfs/layer.h>
#include <miscfs/genfs/layer_extern.h>
#include <miscfs/genfs/genfs.h>
/*
* This is the 08-June-99 bypass routine, based on the 10-Apr-92 bypass
* routine by John Heidemann.
* The new element for this version is that the whole nullfs
* system gained the concept of locks on the lower node, and locks on
* our nodes. When returning from a call to the lower layer, we may
* need to update lock state ONLY on our layer. The LAYERFS_UPPER*LOCK()
* macros provide this functionality.
* The 10-Apr-92 version was optimized for speed, throwing away some
* safety checks. It should still always work, but it's not as
* robust to programmer errors.
* Define SAFETY to include some error checking code.
*
* In general, we map all vnodes going down and unmap them on the way back.
*
* Also, some BSD vnode operations have the side effect of vrele'ing
* their arguments. With stacking, the reference counts are held
* by the upper node, not the lower one, so we must handle these
* side-effects here. This is not of concern in Sun-derived systems
* since there are no such side-effects.
*
* New for the 08-June-99 version: we also handle operations which unlock
* the passed-in node (typically they vput the node).
*
* This makes the following assumptions:
* - only one returned vpp
* - no INOUT vpp's (Sun's vop_open has one of these)
* - the vnode operation vector of the first vnode should be used
* to determine what implementation of the op should be invoked
* - all mapped vnodes are of our vnode-type (NEEDSWORK:
* problems on rmdir'ing mount points and renaming?)
*/
int
layer_bypass(v)
void *v;
{
struct vop_generic_args /* {
struct vnodeop_desc *a_desc;
<other random data follows, presumably>
} */ *ap = v;
int (**our_vnodeop_p) __P((void *));
struct vnode **this_vp_p;
int error, error1;
struct vnode *old_vps[VDESC_MAX_VPS], *vp0;
struct vnode **vps_p[VDESC_MAX_VPS];
struct vnode ***vppp;
struct vnodeop_desc *descp = ap->a_desc;
int reles, i, flags;
#ifdef SAFETY
/*
* We require at least one vp.
*/
if (descp->vdesc_vp_offsets == NULL ||
descp->vdesc_vp_offsets[0] == VDESC_NO_OFFSET)
panic ("layer_bypass: no vp's in map.\n");
#endif
vps_p[0] = VOPARG_OFFSETTO(struct vnode**,descp->vdesc_vp_offsets[0],ap);
vp0 = *vps_p[0];
flags = MOUNTTOLAYERMOUNT(vp0->v_mount)->layerm_flags;
our_vnodeop_p = vp0->v_op;
if (flags & LAYERFS_MBYPASSDEBUG)
printf ("layer_bypass: %s\n", descp->vdesc_name);
/*
* Map the vnodes going in.
* Later, we'll invoke the operation based on
* the first mapped vnode's operation vector.
*/
reles = descp->vdesc_flags;
for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) {
if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET)
break; /* bail out at end of list */
vps_p[i] = this_vp_p =
VOPARG_OFFSETTO(struct vnode**,descp->vdesc_vp_offsets[i],ap);
/*
* We're not guaranteed that any but the first vnode
* are of our type. Check for and don't map any
* that aren't. (We must always map first vp or vclean fails.)
*/
if (i && (*this_vp_p == NULL ||
(*this_vp_p)->v_op != our_vnodeop_p)) {
old_vps[i] = NULL;
} else {
old_vps[i] = *this_vp_p;
*(vps_p[i]) = LAYERVPTOLOWERVP(*this_vp_p);
/*
* XXX - Several operations have the side effect
* of vrele'ing their vp's. We must account for
* that. (This should go away in the future.)
*/
if (reles & VDESC_VP0_WILLRELE)
VREF(*this_vp_p);
}
}
/*
* Call the operation on the lower layer
* with the modified argument structure.
*/
error = VCALL(*vps_p[0], descp->vdesc_offset, ap);
/*
* Maintain the illusion of call-by-value
* by restoring vnodes in the argument structure
* to their original value.
*/
reles = descp->vdesc_flags;
for (i = 0; i < VDESC_MAX_VPS; reles >>= 1, i++) {
if (descp->vdesc_vp_offsets[i] == VDESC_NO_OFFSET)
break; /* bail out at end of list */
if (old_vps[i]) {
*(vps_p[i]) = old_vps[i];
if (reles & VDESC_VP0_WILLUNLOCK)
LAYERFS_UPPERUNLOCK(*(vps_p[i]), 0, error1);
if (reles & VDESC_VP0_WILLRELE)
vrele(*(vps_p[i]));
}
}
/*
* Map the possible out-going vpp
* (Assumes that the lower layer always returns
* a VREF'ed vpp unless it gets an error.)
*/
if (descp->vdesc_vpp_offset != VDESC_NO_OFFSET &&
!(descp->vdesc_flags & VDESC_NOMAP_VPP) &&
!error) {
/*
* XXX - even though some ops have vpp returned vp's,
* several ops actually vrele this before returning.
* We must avoid these ops.
* (This should go away when these ops are regularized.)
*/
if (descp->vdesc_flags & VDESC_VPP_WILLRELE)
goto out;
vppp = VOPARG_OFFSETTO(struct vnode***,
descp->vdesc_vpp_offset,ap);
/*
* Only vop_lookup, vop_create, vop_makedir, vop_bmap,
* vop_mknod, and vop_symlink return vpp's. The latter
* two are VPP_WILLRELE, so we won't get here, and vop_bmap
* doesn't call bypass as the lower vpp is fine (we're just
* going to do i/o on it). vop_loookup doesn't call bypass
* as a lookup on "." would generate a locking error.
* So all the calls which get us here have a locked vpp. :-)
*/
error = layer_node_create(old_vps[0]->v_mount, **vppp, *vppp);
}
out:
return (error);
}
/*
* We have to carry on the locking protocol on the layer vnodes
* as we progress through the tree. We also have to enforce read-only
* if this layer is mounted read-only.
*/
int
layer_lookup(v)
void *v;
{
struct vop_lookup_args /* {
struct vnodeop_desc *a_desc;
struct vnode * a_dvp;
struct vnode ** a_vpp;
struct componentname * a_cnp;
} */ *ap = v;
struct componentname *cnp = ap->a_cnp;
int flags = cnp->cn_flags;
struct vnode *dvp, *vp, *ldvp;
int error, r;
dvp = ap->a_dvp;
if ((flags & ISLASTCN) && (dvp->v_mount->mnt_flag & MNT_RDONLY) &&
(cnp->cn_nameiop == DELETE || cnp->cn_nameiop == RENAME))
return (EROFS);
ldvp = LAYERVPTOLOWERVP(dvp);
ap->a_dvp = ldvp;
error = VCALL(ldvp, ap->a_desc->vdesc_offset, ap);
vp = *ap->a_vpp;
if (error == EJUSTRETURN && (flags & ISLASTCN) &&
(dvp->v_mount->mnt_flag & MNT_RDONLY) &&
(cnp->cn_nameiop == CREATE || cnp->cn_nameiop == RENAME))
error = EROFS;
/*
* We must do the same locking and unlocking at this layer as
* is done in the layers below us. It used to be we would try
* to guess based on what was set with the flags and error codes.
*
* But that doesn't work. So now we have the underlying VOP_LOOKUP
* tell us if it released the parent vnode, and we adjust the
* upper node accordingly. We can't just look at the lock states
* of the lower nodes as someone else might have come along and
* locked the parent node after our call to VOP_LOOKUP locked it.
*/
if ((cnp->cn_flags & PDIRUNLOCK)) {
LAYERFS_UPPERUNLOCK(dvp, 0, r);
}
if (ldvp == vp) {
/*
* Did lookup on "." or ".." in the root node of a mount point.
* So we return dvp after a VREF.
*/
*ap->a_vpp = dvp;
VREF(dvp);
vrele(vp);
} else if (vp != NULL) {
error = layer_node_create(dvp->v_mount, vp, ap->a_vpp);
}
return (error);
}
/*
* Setattr call. Disallow write attempts if the layer is mounted read-only.
*/
int
layer_setattr(v)
void *v;
{
struct vop_setattr_args /* {
struct vnodeop_desc *a_desc;
struct vnode *a_vp;
struct vattr *a_vap;
struct ucred *a_cred;
struct proc *a_p;
} */ *ap = v;
struct vnode *vp = ap->a_vp;
struct vattr *vap = ap->a_vap;
if ((vap->va_flags != VNOVAL || vap->va_uid != (uid_t)VNOVAL ||
vap->va_gid != (gid_t)VNOVAL || vap->va_atime.tv_sec != VNOVAL ||
vap->va_mtime.tv_sec != VNOVAL || vap->va_mode != (mode_t)VNOVAL) &&
(vp->v_mount->mnt_flag & MNT_RDONLY))
return (EROFS);
if (vap->va_size != VNOVAL) {
switch (vp->v_type) {
case VDIR:
return (EISDIR);
case VCHR:
case VBLK:
case VSOCK:
case VFIFO:
return (0);
case VREG:
case VLNK:
default:
/*
* Disallow write attempts if the filesystem is
* mounted read-only.
*/
if (vp->v_mount->mnt_flag & MNT_RDONLY)
return (EROFS);
}
}
return (LAYERFS_DO_BYPASS(vp, ap));
}
/*
* We handle getattr only to change the fsid.
*/
int
layer_getattr(v)
void *v;
{
struct vop_getattr_args /* {
struct vnode *a_vp;
struct vattr *a_vap;
struct ucred *a_cred;
struct proc *a_p;
} */ *ap = v;
struct vnode *vp = ap->a_vp;
int error;
if ((error = LAYERFS_DO_BYPASS(vp, ap)) != 0)
return (error);
/* Requires that arguments be restored. */
ap->a_vap->va_fsid = vp->v_mount->mnt_stat.f_fsid.val[0];
return (0);
}
int
layer_access(v)
void *v;
{
struct vop_access_args /* {
struct vnode *a_vp;
int a_mode;
struct ucred *a_cred;
struct proc *a_p;
} */ *ap = v;
struct vnode *vp = ap->a_vp;
mode_t mode = ap->a_mode;
/*
* Disallow write attempts on read-only layers;
* unless the file is a socket, fifo, or a block or
* character device resident on the file system.
*/
if (mode & VWRITE) {
switch (vp->v_type) {
case VDIR:
case VLNK:
case VREG:
if (vp->v_mount->mnt_flag & MNT_RDONLY)
return (EROFS);
break;
default:
break;
}
}
return (LAYERFS_DO_BYPASS(vp, ap));
}
/*
* We must handle open to be able to catch MNT_NODEV and friends.
*/
int
layer_open(v)
void *v;
{
struct vop_open_args *ap = v;
struct vnode *vp = ap->a_vp;
enum vtype lower_type = LAYERVPTOLOWERVP(vp)->v_type;
if (((lower_type == VBLK) || (lower_type == VCHR)) &&
(vp->v_mount->mnt_flag & MNT_NODEV))
return ENXIO;
return LAYERFS_DO_BYPASS(vp, ap);
}
/*
* We need to process our own vnode lock and then clear the
* interlock flag as it applies only to our vnode, not the
* vnodes below us on the stack.
*/
int
layer_lock(v)
void *v;
{
struct vop_lock_args /* {
struct vnode *a_vp;
int a_flags;
struct proc *a_p;
} */ *ap = v;
struct vnode *vp = ap->a_vp, *lowervp;
int flags = ap->a_flags, error;
if (vp->v_vnlock != NULL) {
/*
* The lower level has exported a struct lock to us. Use
* it so that all vnodes in the stack lock and unlock
* simultaneously. Note: we don't DRAIN the lock as DRAIN
* decommissions the lock - just because our vnode is
* going away doesn't mean the struct lock below us is.
* LK_EXCLUSIVE is fine.
*/
if ((flags & LK_TYPE_MASK) == LK_DRAIN) {
return(lockmgr(vp->v_vnlock,
(flags & ~LK_TYPE_MASK) | LK_EXCLUSIVE,
&vp->v_interlock));
} else
return(lockmgr(vp->v_vnlock, flags, &vp->v_interlock));
} else {
/*
* Ahh well. It would be nice if the fs we're over would
* export a struct lock for us to use, but it doesn't.
*
* To prevent race conditions involving doing a lookup
* on "..", we have to lock the lower node, then lock our
* node. Most of the time it won't matter that we lock our
* node (as any locking would need the lower one locked
* first). But we can LK_DRAIN the upper lock as a step
* towards decomissioning it.
*/
lowervp = LAYERVPTOLOWERVP(vp);
if (flags & LK_INTERLOCK) {
simple_unlock(&vp->v_interlock);
flags &= ~LK_INTERLOCK;
}
if ((flags & LK_TYPE_MASK) == LK_DRAIN) {
error = VOP_LOCK(lowervp,
(flags & ~LK_TYPE_MASK) | LK_EXCLUSIVE);
} else
error = VOP_LOCK(lowervp, flags);
if (error)
return (error);
if ((error = lockmgr(&vp->v_lock, flags, &vp->v_interlock))) {
VOP_UNLOCK(lowervp, 0);
}
return (error);
}
}
/*
*/
int
layer_unlock(v)
void *v;
{
struct vop_unlock_args /* {
struct vnode *a_vp;
int a_flags;
struct proc *a_p;
} */ *ap = v;
struct vnode *vp = ap->a_vp;
int flags = ap->a_flags;
if (vp->v_vnlock != NULL) {
return (lockmgr(vp->v_vnlock, ap->a_flags | LK_RELEASE,
&vp->v_interlock));
} else {
if (flags & LK_INTERLOCK) {
simple_unlock(&vp->v_interlock);
flags &= ~LK_INTERLOCK;
}
VOP_UNLOCK(LAYERVPTOLOWERVP(vp), flags);
return (lockmgr(&vp->v_lock, ap->a_flags | LK_RELEASE,
&vp->v_interlock));
}
}
/*
* As long as genfs_nolock is in use, don't call VOP_ISLOCKED(lowervp)
* if vp->v_vnlock == NULL as genfs_noislocked will always report 0.
*/
int
layer_islocked(v)
void *v;
{
struct vop_islocked_args /* {
struct vnode *a_vp;
} */ *ap = v;
struct vnode *vp = ap->a_vp;
if (vp->v_vnlock != NULL)
return (lockstatus(vp->v_vnlock));
else
return (lockstatus(&vp->v_lock));
}
/*
* If vinvalbuf is calling us, it's a "shallow fsync" -- don't bother
* syncing the underlying vnodes, since they'll be fsync'ed when
* reclaimed; otherwise,
* pass it through to the underlying layer.
*
* XXX Do we still need to worry about shallow fsync?
*/
int
layer_fsync(v)
void *v;
{
struct vop_fsync_args /* {
struct vnode *a_vp;
struct ucred *a_cred;
int a_flags;
off_t offlo;
off_t offhi;
struct proc *a_p;
} */ *ap = v;
if (ap->a_flags & FSYNC_RECLAIM) {
return 0;
}
return (LAYERFS_DO_BYPASS(ap->a_vp, ap));
}
int
layer_inactive(v)
void *v;
{
struct vop_inactive_args /* {
struct vnode *a_vp;
struct proc *a_p;
} */ *ap = v;
struct vnode *vp = ap->a_vp;
/*
* Do nothing (and _don't_ bypass).
* Wait to vrele lowervp until reclaim,
* so that until then our layer_node is in the
* cache and reusable.
*
* NEEDSWORK: Someday, consider inactive'ing
* the lowervp and then trying to reactivate it
* with capabilities (v_id)
* like they do in the name lookup cache code.
* That's too much work for now.
*/
VOP_UNLOCK(vp, 0);
/* ..., but don't cache the device node. */
if (vp->v_type == VBLK || vp->v_type == VCHR)
vgone(vp);
return (0);
}
int
layer_reclaim(v)
void *v;
{
struct vop_reclaim_args /* {
struct vnode *a_vp;
struct proc *a_p;
} */ *ap = v;
struct vnode *vp = ap->a_vp;
struct layer_mount *lmp = MOUNTTOLAYERMOUNT(vp->v_mount);
struct layer_node *xp = VTOLAYER(vp);
struct vnode *lowervp = xp->layer_lowervp;
/*
* Note: in vop_reclaim, the node's struct lock has been
* decomissioned, so we have to be careful about calling
* VOP's on ourself. Even if we turned a LK_DRAIN into an
* LK_EXCLUSIVE in layer_lock, we still must be careful as VXLOCK is
* set.
*/
/* After this assignment, this node will not be re-used. */
if ((vp == lmp->layerm_rootvp)) {
/*
* Oops! We no longer have a root node. Most likely reason is
* that someone forcably unmunted the underlying fs.
*
* Now getting the root vnode will fail. We're dead. :-(
*/
lmp->layerm_rootvp = NULL;
}
xp->layer_lowervp = NULL;
simple_lock(&lmp->layerm_hashlock);
LIST_REMOVE(xp, layer_hash);
simple_unlock(&lmp->layerm_hashlock);
FREE(vp->v_data, M_TEMP);
vp->v_data = NULL;
vrele (lowervp);
return (0);
}
/*
* We just feed the returned vnode up to the caller - there's no need
* to build a layer node on top of the node on which we're going to do
* i/o. :-)
*/
int
layer_bmap(v)
void *v;
{
struct vop_bmap_args /* {
struct vnode *a_vp;
daddr_t a_bn;
struct vnode **a_vpp;
daddr_t *a_bnp;
int *a_runp;
} */ *ap = v;
struct vnode *vp;
ap->a_vp = vp = LAYERVPTOLOWERVP(ap->a_vp);
return (VCALL(vp, ap->a_desc->vdesc_offset, ap));
}
int
layer_print(v)
void *v;
{
struct vop_print_args /* {
struct vnode *a_vp;
} */ *ap = v;
struct vnode *vp = ap->a_vp;
printf ("\ttag VT_LAYERFS, vp=%p, lowervp=%p\n", vp, LAYERVPTOLOWERVP(vp));
return (0);
}
/*
* XXX - vop_strategy must be hand coded because it has no
* vnode in its arguments.
* This goes away with a merged VM/buffer cache.
*/
int
layer_strategy(v)
void *v;
{
struct vop_strategy_args /* {
struct buf *a_bp;
} */ *ap = v;
struct buf *bp = ap->a_bp;
int error;
struct vnode *savedvp;
savedvp = bp->b_vp;
bp->b_vp = LAYERVPTOLOWERVP(bp->b_vp);
error = VOP_STRATEGY(bp);
bp->b_vp = savedvp;
return (error);
}
/*
* XXX - like vop_strategy, vop_bwrite must be hand coded because it has no
* vnode in its arguments.
* This goes away with a merged VM/buffer cache.
*/
int
layer_bwrite(v)
void *v;
{
struct vop_bwrite_args /* {
struct buf *a_bp;
} */ *ap = v;
struct buf *bp = ap->a_bp;
int error;
struct vnode *savedvp;
savedvp = bp->b_vp;
bp->b_vp = LAYERVPTOLOWERVP(bp->b_vp);
error = VOP_BWRITE(bp);
bp->b_vp = savedvp;
return (error);
}
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