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Add new function vunref(9) that decrements vnode use count (and hold

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count) while vnode is exclusively locked.

The code for vput(9), vrele(9) and vunref(9) is merged.

In collaboration with:	pho
Reviewed by:	alc
MFC after:	3 weeks
This commit is contained in:
Konstantin Belousov 2010-01-17 21:24:27 +00:00
parent e35a88d3a6
commit d2f334bfc9
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=202528
2 changed files with 54 additions and 70 deletions
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123
sys/kern/vfs_subr.c
View File

@ -2149,37 +2149,44 @@ vrefcnt(struct vnode *vp)
return (usecnt);
}
#define VPUTX_VRELE 1
#define VPUTX_VPUT 2
#define VPUTX_VUNREF 3
/*
* Vnode put/release.
* If count drops to zero, call inactive routine and return to freelist.
*/
void
vrele(struct vnode *vp)
static void
vputx(struct vnode *vp, int func)
{
struct thread *td = curthread; /* XXX */
int error;
KASSERT(vp != NULL, ("vrele: null vp"));
KASSERT(vp != NULL, ("vputx: null vp"));
if (func == VPUTX_VUNREF)
ASSERT_VOP_ELOCKED(vp, "vunref");
else if (func == VPUTX_VPUT)
ASSERT_VOP_LOCKED(vp, "vput");
else
KASSERT(func == VPUTX_VRELE, ("vputx: wrong func"));
VFS_ASSERT_GIANT(vp->v_mount);
CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
VI_LOCK(vp);
/* Skip this v_writecount check if we're going to panic below. */
VNASSERT(vp->v_writecount < vp->v_usecount || vp->v_usecount < 1, vp,
("vrele: missed vn_close"));
CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
("vputx: missed vn_close"));
error = 0;
if (vp->v_usecount > 1 || ((vp->v_iflag & VI_DOINGINACT) &&
vp->v_usecount == 1)) {
if (func == VPUTX_VPUT)
VOP_UNLOCK(vp, 0);
v_decr_usecount(vp);
return;
}
if (vp->v_usecount != 1) {
#ifdef DIAGNOSTIC
vprint("vrele: negative ref count", vp);
vprint("vputx: negative ref count", vp);
#endif
VI_UNLOCK(vp);
panic("vrele: negative ref cnt");
panic("vputx: negative ref cnt");
}
CTR2(KTR_VFS, "%s: return vnode %p to the freelist", __func__, vp);
/*
@ -2193,21 +2200,35 @@ vrele(struct vnode *vp)
* as VI_DOINGINACT to avoid recursion.
*/
vp->v_iflag |= VI_OWEINACT;
if (vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK) == 0) {
if (func == VPUTX_VRELE) {
error = vn_lock(vp, LK_EXCLUSIVE | LK_INTERLOCK);
VI_LOCK(vp);
if (vp->v_usecount > 0)
vp->v_iflag &= ~VI_OWEINACT;
} else if (func == VPUTX_VPUT && VOP_ISLOCKED(vp) != LK_EXCLUSIVE) {
error = VOP_LOCK(vp, LK_UPGRADE | LK_INTERLOCK | LK_NOWAIT);
VI_LOCK(vp);
}
if (vp->v_usecount > 0)
vp->v_iflag &= ~VI_OWEINACT;
if (error == 0) {
if (vp->v_iflag & VI_OWEINACT)
vinactive(vp, td);
VOP_UNLOCK(vp, 0);
} else {
VI_LOCK(vp);
if (vp->v_usecount > 0)
vp->v_iflag &= ~VI_OWEINACT;
vinactive(vp, curthread);
if (func != VPUTX_VUNREF)
VOP_UNLOCK(vp, 0);
}
vdropl(vp);
}
/*
* Vnode put/release.
* If count drops to zero, call inactive routine and return to freelist.
*/
void
vrele(struct vnode *vp)
{
vputx(vp, VPUTX_VRELE);
}
/*
* Release an already locked vnode. This give the same effects as
* unlock+vrele(), but takes less time and avoids releasing and
@ -2216,56 +2237,18 @@ vrele(struct vnode *vp)
void
vput(struct vnode *vp)
{
struct thread *td = curthread; /* XXX */
int error;
KASSERT(vp != NULL, ("vput: null vp"));
ASSERT_VOP_LOCKED(vp, "vput");
VFS_ASSERT_GIANT(vp->v_mount);
CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
VI_LOCK(vp);
/* Skip this v_writecount check if we're going to panic below. */
VNASSERT(vp->v_writecount < vp->v_usecount || vp->v_usecount < 1, vp,
("vput: missed vn_close"));
error = 0;
vputx(vp, VPUTX_VPUT);
}
if (vp->v_usecount > 1 || ((vp->v_iflag & VI_DOINGINACT) &&
vp->v_usecount == 1)) {
VOP_UNLOCK(vp, 0);
v_decr_usecount(vp);
return;
}
/*
* Release an exclusively locked vnode. Do not unlock the vnode lock.
*/
void
vunref(struct vnode *vp)
{
if (vp->v_usecount != 1) {
#ifdef DIAGNOSTIC
vprint("vput: negative ref count", vp);
#endif
panic("vput: negative ref cnt");
}
CTR2(KTR_VFS, "%s: return to freelist the vnode %p", __func__, vp);
/*
* We want to hold the vnode until the inactive finishes to
* prevent vgone() races. We drop the use count here and the
* hold count below when we're done.
*/
v_decr_useonly(vp);
vp->v_iflag |= VI_OWEINACT;
if (VOP_ISLOCKED(vp) != LK_EXCLUSIVE) {
error = VOP_LOCK(vp, LK_UPGRADE|LK_INTERLOCK|LK_NOWAIT);
VI_LOCK(vp);
if (error) {
if (vp->v_usecount > 0)
vp->v_iflag &= ~VI_OWEINACT;
goto done;
}
}
if (vp->v_usecount > 0)
vp->v_iflag &= ~VI_OWEINACT;
if (vp->v_iflag & VI_OWEINACT)
vinactive(vp, td);
VOP_UNLOCK(vp, 0);
done:
vdropl(vp);
vputx(vp, VPUTX_VUNREF);
}
/*

1
sys/sys/vnode.h
View File

@ -632,6 +632,7 @@ void vholdl(struct vnode *);
int vinvalbuf(struct vnode *vp, int save, int slpflag, int slptimeo);
int vtruncbuf(struct vnode *vp, struct ucred *cred, struct thread *td,
off_t length, int blksize);
void vunref(struct vnode *);
void vn_printf(struct vnode *vp, const char *fmt, ...) __printflike(2,3);
#define vprint(label, vp) vn_printf((vp), "%s\n", (label))
int vrecycle(struct vnode *vp, struct thread *td);