vfs: introduce vnode sequence counters

Modified on each permission change and link/unlink.

Reviewed by:	kib
Tested by:	pho (in a patchset)
Differential Revision:	https://reviews.freebsd.org/D25573
This commit is contained in:
Mateusz Guzik 2020-07-25 10:31:52 +00:00
parent 82dc812235
commit 0379ff6ae3
5 changed files with 395 additions and 41 deletions

View file

@ -154,6 +154,7 @@ mount_snapshot(kthread_t *td, vnode_t **vpp, const char *fstype, char *fspath,
vput(vp);
return (error);
}
vn_seqc_write_begin(vp);
VOP_UNLOCK(vp);
/*
@ -206,6 +207,7 @@ mount_snapshot(kthread_t *td, vnode_t **vpp, const char *fstype, char *fspath,
VI_LOCK(vp);
vp->v_iflag &= ~VI_MOUNT;
VI_UNLOCK(vp);
vn_seqc_write_end(vp);
vput(vp);
vfs_unbusy(mp);
vfs_freeopts(mp->mnt_optnew);
@ -241,6 +243,7 @@ mount_snapshot(kthread_t *td, vnode_t **vpp, const char *fstype, char *fspath,
vfs_event_signal(NULL, VQ_MOUNT, 0);
if (VFS_ROOT(mp, LK_EXCLUSIVE, &mvp))
panic("mount: lost mount");
vn_seqc_write_end(vp);
VOP_UNLOCK(vp);
vfs_op_exit(mp);
vfs_unbusy(mp);

View file

@ -947,6 +947,7 @@ vfs_domount_first(
vput(vp);
return (error);
}
vn_seqc_write_begin(vp);
VOP_UNLOCK(vp);
/* Allocate and initialize the filesystem. */
@ -979,9 +980,11 @@ vfs_domount_first(
VI_LOCK(vp);
vp->v_iflag &= ~VI_MOUNT;
VI_UNLOCK(vp);
vn_seqc_write_end(vp);
vrele(vp);
return (error);
}
vn_seqc_write_begin(newdp);
VOP_UNLOCK(newdp);
if (mp->mnt_opt != NULL)
@ -1018,6 +1021,8 @@ vfs_domount_first(
EVENTHANDLER_DIRECT_INVOKE(vfs_mounted, mp, newdp, td);
VOP_UNLOCK(newdp);
mountcheckdirs(vp, newdp);
vn_seqc_write_end(vp);
vn_seqc_write_end(newdp);
vrele(newdp);
if ((mp->mnt_flag & MNT_RDONLY) == 0)
vfs_allocate_syncvnode(mp);
@ -1094,7 +1099,9 @@ vfs_domount_update(
VOP_UNLOCK(vp);
vfs_op_enter(mp);
vn_seqc_write_begin(vp);
rootvp = NULL;
MNT_ILOCK(mp);
if ((mp->mnt_kern_flag & MNTK_UNMOUNT) != 0) {
MNT_IUNLOCK(mp);
@ -1108,8 +1115,6 @@ vfs_domount_update(
mp->mnt_kern_flag &= ~MNTK_ASYNC;
rootvp = vfs_cache_root_clear(mp);
MNT_IUNLOCK(mp);
if (rootvp != NULL)
vrele(rootvp);
mp->mnt_optnew = *optlist;
vfs_mergeopts(mp->mnt_optnew, mp->mnt_opt);
@ -1233,6 +1238,11 @@ vfs_domount_update(
vfs_deallocate_syncvnode(mp);
end:
vfs_op_exit(mp);
if (rootvp != NULL) {
vn_seqc_write_end(rootvp);
vrele(rootvp);
}
vn_seqc_write_end(vp);
vfs_unbusy(mp);
VI_LOCK(vp);
vp->v_iflag &= ~VI_MOUNT;
@ -1723,14 +1733,19 @@ dounmount(struct mount *mp, int flags, struct thread *td)
}
mp->mnt_kern_flag |= MNTK_UNMOUNT;
rootvp = vfs_cache_root_clear(mp);
if (coveredvp != NULL)
vn_seqc_write_begin(coveredvp);
if (flags & MNT_NONBUSY) {
MNT_IUNLOCK(mp);
error = vfs_check_usecounts(mp);
MNT_ILOCK(mp);
if (error != 0) {
vn_seqc_write_end(coveredvp);
dounmount_cleanup(mp, coveredvp, MNTK_UNMOUNT);
if (rootvp != NULL)
if (rootvp != NULL) {
vn_seqc_write_end(rootvp);
vrele(rootvp);
}
return (error);
}
}
@ -1759,22 +1774,19 @@ dounmount(struct mount *mp, int flags, struct thread *td)
("%s: invalid return value for msleep in the drain path @ %s:%d",
__func__, __FILE__, __LINE__));
if (rootvp != NULL)
/*
* We want to keep the vnode around so that we can vn_seqc_write_end
* after we are done with unmount. Downgrade our reference to a mere
* hold count so that we don't interefere with anything.
*/
if (rootvp != NULL) {
vhold(rootvp);
vrele(rootvp);
}
if (mp->mnt_flag & MNT_EXPUBLIC)
vfs_setpublicfs(NULL, NULL, NULL);
/*
* From now, we can claim that the use reference on the
* coveredvp is ours, and the ref can be released only by
* successfull unmount by us, or left for later unmount
* attempt. The previously acquired hold reference is no
* longer needed to protect the vnode from reuse.
*/
if (coveredvp != NULL)
vdrop(coveredvp);
vfs_periodic(mp, MNT_WAIT);
MNT_ILOCK(mp);
async_flag = mp->mnt_flag & MNT_ASYNC;
@ -1809,8 +1821,15 @@ dounmount(struct mount *mp, int flags, struct thread *td)
}
vfs_op_exit_locked(mp);
MNT_IUNLOCK(mp);
if (coveredvp)
if (coveredvp) {
vn_seqc_write_end(coveredvp);
VOP_UNLOCK(coveredvp);
vdrop(coveredvp);
}
if (rootvp != NULL) {
vn_seqc_write_end(rootvp);
vdrop(rootvp);
}
return (error);
}
mtx_lock(&mountlist_mtx);
@ -1819,7 +1838,13 @@ dounmount(struct mount *mp, int flags, struct thread *td)
EVENTHANDLER_DIRECT_INVOKE(vfs_unmounted, mp, td);
if (coveredvp != NULL) {
coveredvp->v_mountedhere = NULL;
vn_seqc_write_end(coveredvp);
VOP_UNLOCK(coveredvp);
vdrop(coveredvp);
}
if (rootvp != NULL) {
vn_seqc_write_end(rootvp);
vdrop(rootvp);
}
vfs_event_signal(NULL, VQ_UNMOUNT, 0);
if (rootvnode != NULL && mp == rootvnode->v_mount) {

View file

@ -1761,6 +1761,12 @@ freevnode(struct vnode *vp)
* so as not to contaminate the freshly allocated vnode.
*/
CTR2(KTR_VFS, "%s: destroying the vnode %p", __func__, vp);
/*
* Paired with vgone.
*/
vn_seqc_write_end_locked(vp);
VNPASS(vp->v_seqc_users == 0, vp);
bo = &vp->v_bufobj;
VNASSERT(vp->v_data == NULL, vp, ("cleaned vnode isn't"));
VNPASS(vp->v_holdcnt == VHOLD_NO_SMR, vp);
@ -4018,6 +4024,10 @@ vgonel(struct vnode *vp)
*/
if (vp->v_irflag & VIRF_DOOMED)
return;
/*
* Paired with freevnode.
*/
vn_seqc_write_begin_locked(vp);
vunlazy_gone(vp);
vp->v_irflag |= VIRF_DOOMED;
@ -4160,8 +4170,9 @@ vn_printf(struct vnode *vp, const char *fmt, ...)
printf("%p: ", (void *)vp);
printf("type %s\n", typename[vp->v_type]);
holdcnt = atomic_load_int(&vp->v_holdcnt);
printf(" usecount %d, writecount %d, refcount %d",
vp->v_usecount, vp->v_writecount, holdcnt & ~VHOLD_ALL_FLAGS);
printf(" usecount %d, writecount %d, refcount %d seqc users %d",
vp->v_usecount, vp->v_writecount, holdcnt & ~VHOLD_ALL_FLAGS,
vp->v_seqc_users);
switch (vp->v_type) {
case VDIR:
printf(" mountedhere %p\n", vp->v_mountedhere);
@ -5508,6 +5519,14 @@ vop_rename_pre(void *ap)
ASSERT_VOP_LOCKED(a->a_tvp, "vop_rename: tvp not locked");
ASSERT_VOP_LOCKED(a->a_tdvp, "vop_rename: tdvp not locked");
#endif
/*
* It may be tempting to add vn_seqc_write_begin/end calls here and
* in vop_rename_post but that's not going to work out since some
* filesystems relookup vnodes mid-rename. This is probably a bug.
*
* For now filesystems are expected to do the relevant calls after they
* decide what vnodes to operate on.
*/
if (a->a_tdvp != a->a_fdvp)
vhold(a->a_fdvp);
if (a->a_tvp != a->a_fvp)
@ -5588,70 +5607,194 @@ vop_need_inactive_post(void *ap, int rc)
}
#endif
void
vop_create_pre(void *ap)
{
struct vop_create_args *a;
struct vnode *dvp;
a = ap;
dvp = a->a_dvp;
vn_seqc_write_begin(dvp);
}
void
vop_create_post(void *ap, int rc)
{
struct vop_create_args *a = ap;
struct vop_create_args *a;
struct vnode *dvp;
a = ap;
dvp = a->a_dvp;
vn_seqc_write_end(dvp);
if (!rc)
VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
VFS_KNOTE_LOCKED(dvp, NOTE_WRITE);
}
void
vop_whiteout_pre(void *ap)
{
struct vop_whiteout_args *a;
struct vnode *dvp;
a = ap;
dvp = a->a_dvp;
vn_seqc_write_begin(dvp);
}
void
vop_whiteout_post(void *ap, int rc)
{
struct vop_whiteout_args *a;
struct vnode *dvp;
a = ap;
dvp = a->a_dvp;
vn_seqc_write_end(dvp);
}
void
vop_deleteextattr_pre(void *ap)
{
struct vop_deleteextattr_args *a;
struct vnode *vp;
a = ap;
vp = a->a_vp;
vn_seqc_write_begin(vp);
}
void
vop_deleteextattr_post(void *ap, int rc)
{
struct vop_deleteextattr_args *a = ap;
struct vop_deleteextattr_args *a;
struct vnode *vp;
a = ap;
vp = a->a_vp;
vn_seqc_write_end(vp);
if (!rc)
VFS_KNOTE_LOCKED(a->a_vp, NOTE_ATTRIB);
}
void
vop_link_pre(void *ap)
{
struct vop_link_args *a;
struct vnode *vp, *tdvp;
a = ap;
vp = a->a_vp;
tdvp = a->a_tdvp;
vn_seqc_write_begin(vp);
vn_seqc_write_begin(tdvp);
}
void
vop_link_post(void *ap, int rc)
{
struct vop_link_args *a = ap;
struct vop_link_args *a;
struct vnode *vp, *tdvp;
a = ap;
vp = a->a_vp;
tdvp = a->a_tdvp;
vn_seqc_write_end(vp);
vn_seqc_write_end(tdvp);
if (!rc) {
VFS_KNOTE_LOCKED(a->a_vp, NOTE_LINK);
VFS_KNOTE_LOCKED(a->a_tdvp, NOTE_WRITE);
VFS_KNOTE_LOCKED(vp, NOTE_LINK);
VFS_KNOTE_LOCKED(tdvp, NOTE_WRITE);
}
}
void
vop_mkdir_pre(void *ap)
{
struct vop_mkdir_args *a;
struct vnode *dvp;
a = ap;
dvp = a->a_dvp;
vn_seqc_write_begin(dvp);
}
void
vop_mkdir_post(void *ap, int rc)
{
struct vop_mkdir_args *a = ap;
struct vop_mkdir_args *a;
struct vnode *dvp;
a = ap;
dvp = a->a_dvp;
vn_seqc_write_end(dvp);
if (!rc)
VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE | NOTE_LINK);
VFS_KNOTE_LOCKED(dvp, NOTE_WRITE | NOTE_LINK);
}
void
vop_mknod_pre(void *ap)
{
struct vop_mknod_args *a;
struct vnode *dvp;
a = ap;
dvp = a->a_dvp;
vn_seqc_write_begin(dvp);
}
void
vop_mknod_post(void *ap, int rc)
{
struct vop_mknod_args *a = ap;
struct vop_mknod_args *a;
struct vnode *dvp;
a = ap;
dvp = a->a_dvp;
vn_seqc_write_end(dvp);
if (!rc)
VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
VFS_KNOTE_LOCKED(dvp, NOTE_WRITE);
}
void
vop_reclaim_post(void *ap, int rc)
{
struct vop_reclaim_args *a = ap;
struct vop_reclaim_args *a;
struct vnode *vp;
a = ap;
vp = a->a_vp;
ASSERT_VOP_IN_SEQC(vp);
if (!rc)
VFS_KNOTE_LOCKED(a->a_vp, NOTE_REVOKE);
VFS_KNOTE_LOCKED(vp, NOTE_REVOKE);
}
void
vop_remove_pre(void *ap)
{
struct vop_remove_args *a;
struct vnode *dvp, *vp;
a = ap;
dvp = a->a_dvp;
vp = a->a_vp;
vn_seqc_write_begin(dvp);
vn_seqc_write_begin(vp);
}
void
vop_remove_post(void *ap, int rc)
{
struct vop_remove_args *a = ap;
struct vop_remove_args *a;
struct vnode *dvp, *vp;
a = ap;
dvp = a->a_dvp;
vp = a->a_vp;
vn_seqc_write_end(dvp);
vn_seqc_write_end(vp);
if (!rc) {
VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
VFS_KNOTE_LOCKED(a->a_vp, NOTE_DELETE);
VFS_KNOTE_LOCKED(dvp, NOTE_WRITE);
VFS_KNOTE_LOCKED(vp, NOTE_DELETE);
}
}
@ -5693,42 +5836,128 @@ vop_rename_post(void *ap, int rc)
vdrop(a->a_tvp);
}
void
vop_rmdir_pre(void *ap)
{
struct vop_rmdir_args *a;
struct vnode *dvp, *vp;
a = ap;
dvp = a->a_dvp;
vp = a->a_vp;
vn_seqc_write_begin(dvp);
vn_seqc_write_begin(vp);
}
void
vop_rmdir_post(void *ap, int rc)
{
struct vop_rmdir_args *a = ap;
struct vop_rmdir_args *a;
struct vnode *dvp, *vp;
a = ap;
dvp = a->a_dvp;
vp = a->a_vp;
vn_seqc_write_end(dvp);
vn_seqc_write_end(vp);
if (!rc) {
VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE | NOTE_LINK);
VFS_KNOTE_LOCKED(a->a_vp, NOTE_DELETE);
VFS_KNOTE_LOCKED(dvp, NOTE_WRITE | NOTE_LINK);
VFS_KNOTE_LOCKED(vp, NOTE_DELETE);
}
}
void
vop_setattr_pre(void *ap)
{
struct vop_setattr_args *a;
struct vnode *vp;
a = ap;
vp = a->a_vp;
vn_seqc_write_begin(vp);
}
void
vop_setattr_post(void *ap, int rc)
{
struct vop_setattr_args *a = ap;
struct vop_setattr_args *a;
struct vnode *vp;
a = ap;
vp = a->a_vp;
vn_seqc_write_end(vp);
if (!rc)
VFS_KNOTE_LOCKED(a->a_vp, NOTE_ATTRIB);
VFS_KNOTE_LOCKED(vp, NOTE_ATTRIB);
}
void
vop_setacl_pre(void *ap)
{
struct vop_setacl_args *a;
struct vnode *vp;
a = ap;
vp = a->a_vp;
vn_seqc_write_begin(vp);
}
void
vop_setacl_post(void *ap, int rc __unused)
{
struct vop_setacl_args *a;
struct vnode *vp;
a = ap;
vp = a->a_vp;
vn_seqc_write_end(vp);
}
void
vop_setextattr_pre(void *ap)
{
struct vop_setextattr_args *a;
struct vnode *vp;
a = ap;
vp = a->a_vp;
vn_seqc_write_begin(vp);
}
void
vop_setextattr_post(void *ap, int rc)
{
struct vop_setextattr_args *a = ap;
struct vop_setextattr_args *a;
struct vnode *vp;
a = ap;
vp = a->a_vp;
vn_seqc_write_end(vp);
if (!rc)
VFS_KNOTE_LOCKED(a->a_vp, NOTE_ATTRIB);
VFS_KNOTE_LOCKED(vp, NOTE_ATTRIB);
}
void
vop_symlink_pre(void *ap)
{
struct vop_symlink_args *a;
struct vnode *dvp;
a = ap;
dvp = a->a_dvp;
vn_seqc_write_begin(dvp);
}
void
vop_symlink_post(void *ap, int rc)
{
struct vop_symlink_args *a = ap;
struct vop_symlink_args *a;
struct vnode *dvp;
a = ap;
dvp = a->a_dvp;
vn_seqc_write_end(dvp);
if (!rc)
VFS_KNOTE_LOCKED(a->a_dvp, NOTE_WRITE);
VFS_KNOTE_LOCKED(dvp, NOTE_WRITE);
}
void
@ -6281,6 +6510,8 @@ vfs_cache_root_clear(struct mount *mp)
*/
MPASS(mp->mnt_vfs_ops > 0);
vp = mp->mnt_rootvnode;
if (vp != NULL)
vn_seqc_write_begin(vp);
mp->mnt_rootvnode = NULL;
return (vp);
}
@ -6577,3 +6808,44 @@ vn_dir_check_exec(struct vnode *vp, struct componentname *cnp)
return (VOP_ACCESS(vp, VEXEC, cnp->cn_cred, cnp->cn_thread));
}
void
vn_seqc_write_begin_locked(struct vnode *vp)
{
ASSERT_VI_LOCKED(vp, __func__);
VNPASS(vp->v_holdcnt > 0, vp);
VNPASS(vp->v_seqc_users >= 0, vp);
vp->v_seqc_users++;
if (vp->v_seqc_users == 1)
seqc_sleepable_write_begin(&vp->v_seqc);
}
void
vn_seqc_write_begin(struct vnode *vp)
{
VI_LOCK(vp);
vn_seqc_write_begin_locked(vp);
VI_UNLOCK(vp);
}
void
vn_seqc_write_end_locked(struct vnode *vp)
{
ASSERT_VI_LOCKED(vp, __func__);
VNPASS(vp->v_seqc_users > 0, vp);
vp->v_seqc_users--;
if (vp->v_seqc_users == 0)
seqc_sleepable_write_end(&vp->v_seqc);
}
void
vn_seqc_write_end(struct vnode *vp)
{
VI_LOCK(vp);
vn_seqc_write_end_locked(vp);
VI_UNLOCK(vp);
}

View file

@ -88,6 +88,7 @@ vop_cachedlookup {
%% create dvp E E E
%% create vpp - L -
%! create pre vop_create_pre
%! create post vop_create_post
vop_create {
@ -99,6 +100,8 @@ vop_create {
%% whiteout dvp E E E
%! whiteout pre vop_whiteout_pre
%! whiteout post vop_whiteout_post
vop_whiteout {
IN struct vnode *dvp;
@ -109,6 +112,7 @@ vop_whiteout {
%% mknod dvp E E E
%% mknod vpp - L -
%! mknod pre vop_mknod_pre
%! mknod post vop_mknod_post
vop_mknod {
@ -172,6 +176,7 @@ vop_getattr {
%% setattr vp E E E
%! setattr pre vop_setattr_pre
%! setattr post vop_setattr_post
vop_setattr {
@ -260,6 +265,7 @@ vop_fsync {
%% remove dvp E E E
%% remove vp E E E
%! remove pre vop_remove_pre
%! remove post vop_remove_post
vop_remove {
@ -271,6 +277,7 @@ vop_remove {
%% link tdvp E E E
%% link vp E E E
%! link pre vop_link_pre
%! link post vop_link_post
vop_link {
@ -295,6 +302,7 @@ vop_rename {
%% mkdir dvp E E E
%% mkdir vpp - E -
%! mkdir pre vop_mkdir_pre
%! mkdir post vop_mkdir_post
vop_mkdir {
@ -307,6 +315,7 @@ vop_mkdir {
%% rmdir dvp E E E
%% rmdir vp E E E
%! rmdir pre vop_rmdir_pre
%! rmdir post vop_rmdir_post
vop_rmdir {
@ -318,6 +327,7 @@ vop_rmdir {
%% symlink dvp E E E
%% symlink vpp - E -
%! symlink pre vop_symlink_pre
%! symlink post vop_symlink_post
vop_symlink {
@ -523,6 +533,8 @@ vop_getacl {
%% setacl vp E E E
%! setacl pre vop_setacl_pre
%! setacl post vop_setacl_post
vop_setacl {
IN struct vnode *vp;
@ -589,6 +601,7 @@ vop_openextattr {
%% deleteextattr vp E E E
%! deleteextattr pre vop_deleteextattr_pre
%! deleteextattr post vop_deleteextattr_post
vop_deleteextattr {
@ -601,6 +614,7 @@ vop_deleteextattr {
%% setextattr vp E E E
%! setextattr pre vop_setextattr_pre
%! setextattr post vop_setextattr_post
vop_setextattr {

View file

@ -45,6 +45,7 @@
#include <sys/uio.h>
#include <sys/acl.h>
#include <sys/ktr.h>
#include <sys/_seqc.h>
/*
* The vnode is the focus of all file activity in UNIX. There is a
@ -105,6 +106,7 @@ struct vnode {
*/
enum vtype v_type:8; /* u vnode type */
short v_irflag; /* i frequently read flags */
seqc_t v_seqc; /* i modification count */
struct vop_vector *v_op; /* u vnode operations vector */
void *v_data; /* u private data for fs */
@ -175,6 +177,7 @@ struct vnode {
short v_dbatchcpu; /* i LRU requeue deferral batch */
int v_writecount; /* I ref count of writers or
(negative) text users */
int v_seqc_users; /* i modifications pending */
u_int v_hash;
};
@ -539,6 +542,18 @@ void assert_vop_unlocked(struct vnode *vp, const char *str);
#define ASSERT_VOP_LOCKED(vp, str) assert_vop_locked((vp), (str))
#define ASSERT_VOP_UNLOCKED(vp, str) assert_vop_unlocked((vp), (str))
#define ASSERT_VOP_IN_SEQC(vp) do { \
struct vnode *_vp = (vp); \
\
VNPASS(seqc_in_modify(_vp->v_seqc), _vp); \
} while (0)
#define ASSERT_VOP_NOT_IN_SEQC(vp) do { \
struct vnode *_vp = (vp); \
\
VNPASS(!seqc_in_modify(_vp->v_seqc), _vp); \
} while (0)
#else /* !DEBUG_VFS_LOCKS */
#define ASSERT_VI_LOCKED(vp, str) ((void)0)
@ -546,6 +561,10 @@ void assert_vop_unlocked(struct vnode *vp, const char *str);
#define ASSERT_VOP_ELOCKED(vp, str) ((void)0)
#define ASSERT_VOP_LOCKED(vp, str) ((void)0)
#define ASSERT_VOP_UNLOCKED(vp, str) ((void)0)
#define ASSERT_VOP_IN_SEQC(vp) ((void)0)
#define ASSERT_VOP_NOT_IN_SEQC(vp) ((void)0)
#endif /* DEBUG_VFS_LOCKS */
@ -738,6 +757,13 @@ int vn_io_fault_uiomove(char *data, int xfersize, struct uio *uio);
int vn_io_fault_pgmove(vm_page_t ma[], vm_offset_t offset, int xfersize,
struct uio *uio);
void vn_seqc_write_begin_locked(struct vnode *vp);
void vn_seqc_write_begin(struct vnode *vp);
void vn_seqc_write_end_locked(struct vnode *vp);
void vn_seqc_write_end(struct vnode *vp);
#define vn_seqc_read_any(vp) seqc_read_any(&(vp)->v_seqc)
#define vn_seqc_consistent(vp, seq) seqc_consistent(&(vp)->v_seqc, seq)
#define vn_rangelock_unlock(vp, cookie) \
rangelock_unlock(&(vp)->v_rl, (cookie), VI_MTX(vp))
#define vn_rangelock_unlock_range(vp, cookie, start, end) \
@ -804,23 +830,37 @@ int dead_write(struct vop_write_args *ap);
/* These are called from within the actual VOPS. */
void vop_close_post(void *a, int rc);
void vop_create_pre(void *a);
void vop_create_post(void *a, int rc);
void vop_whiteout_pre(void *a);
void vop_whiteout_post(void *a, int rc);
void vop_deleteextattr_pre(void *a);
void vop_deleteextattr_post(void *a, int rc);
void vop_link_pre(void *a);
void vop_link_post(void *a, int rc);
void vop_lookup_post(void *a, int rc);
void vop_lookup_pre(void *a);
void vop_mkdir_pre(void *a);
void vop_mkdir_post(void *a, int rc);
void vop_mknod_pre(void *a);
void vop_mknod_post(void *a, int rc);
void vop_open_post(void *a, int rc);
void vop_read_post(void *a, int rc);
void vop_readdir_post(void *a, int rc);
void vop_reclaim_post(void *a, int rc);
void vop_remove_pre(void *a);
void vop_remove_post(void *a, int rc);
void vop_rename_post(void *a, int rc);
void vop_rename_pre(void *a);
void vop_rmdir_pre(void *a);
void vop_rmdir_post(void *a, int rc);
void vop_setattr_pre(void *a);
void vop_setattr_post(void *a, int rc);
void vop_setacl_pre(void *a);
void vop_setacl_post(void *a, int rc);
void vop_setextattr_pre(void *a);
void vop_setextattr_post(void *a, int rc);
void vop_symlink_pre(void *a);
void vop_symlink_post(void *a, int rc);
int vop_sigdefer(struct vop_vector *vop, struct vop_generic_args *a);