mirror of
https://github.com/freebsd/freebsd-src
synced 2024-10-19 06:44:31 +00:00
- Move some logic from getnewvnode() to a new function vcanrecycle()
- Unlock the free list mutex around vcanrecycle to prevent a lock order reversal.
This commit is contained in:
Jeff Roberson
parent
3a317a1229
commit
8947be9ba0
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=101367
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@ -80,6 +80,8 @@ static void vclean(struct vnode *vp, int flags, struct thread *td);
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static void vlruvp(struct vnode *vp);
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static int flushbuflist(struct buf *blist, int flags, struct vnode *vp,
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int slpflag, int slptimeo, int *errorp);
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static int vcanrecycle(struct vnode *vp);
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/*
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* Number of vnodes in existence. Increased whenever getnewvnode()
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@ -659,6 +661,70 @@ SYSINIT(vnlru, SI_SUB_KTHREAD_UPDATE, SI_ORDER_FIRST, kproc_start, &vnlru_kp)
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* Routines having to do with the management of the vnode table.
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*/
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/*
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* Check to see if a free vnode can be recycled. If it can, return it locked
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* with the vn lock, but not interlock. Otherwise indicate the error.
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*/
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static int
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vcanrecycle(struct vnode *vp)
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{
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struct thread *td = curthread;
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vm_object_t object;
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int error;
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/* Don't recycle if we can't get the interlock */
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if (!mtx_trylock(&vp->v_interlock))
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return (EWOULDBLOCK);
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/* We should be able to immediately acquire this */
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/* XXX This looks like it should panic if it fails */
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if (vn_lock(vp, LK_INTERLOCK | LK_EXCLUSIVE, td) != 0)
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return (EWOULDBLOCK);
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/*
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* Don't recycle if we still have cached pages.
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*/
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if (VOP_GETVOBJECT(vp, &object) == 0 &&
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(object->resident_page_count ||
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object->ref_count)) {
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VOP_UNLOCK(vp, 0, td);
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error = EBUSY;
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goto done;
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}
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if (LIST_FIRST(&vp->v_cache_src)) {
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/*
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* note: nameileafonly sysctl is temporary,
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* for debugging only, and will eventually be
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* removed.
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*/
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if (nameileafonly > 0) {
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/*
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* Do not reuse namei-cached directory
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* vnodes that have cached
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* subdirectories.
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*/
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if (cache_leaf_test(vp) < 0) {
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error = EISDIR;
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goto done;
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}
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} else if (nameileafonly < 0 ||
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vmiodirenable == 0) {
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/*
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* Do not reuse namei-cached directory
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* vnodes if nameileafonly is -1 or
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* if VMIO backing for directories is
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* turned off (otherwise we reuse them
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* too quickly).
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*/
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error = EBUSY;
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goto done;
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}
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}
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return (0);
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done:
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VOP_UNLOCK(vp, 0, td);
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return (error);
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}
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/*
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* Return the next vnode from the free list.
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*/
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@ -673,7 +739,6 @@ getnewvnode(tag, mp, vops, vpp)
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struct thread *td = curthread; /* XXX */
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struct vnode *vp = NULL;
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struct mount *vnmp;
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vm_object_t object;
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s = splbio();
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/*
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@ -696,84 +761,47 @@ getnewvnode(tag, mp, vops, vpp)
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mtx_lock(&vnode_free_list_mtx);
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if (freevnodes >= wantfreevnodes && numvnodes >= minvnodes) {
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int error;
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int count;
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for (count = 0; count < freevnodes; count++) {
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vp = TAILQ_FIRST(&vnode_free_list);
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if (vp == NULL || vp->v_usecount)
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panic("getnewvnode: free vnode isn't");
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KASSERT(vp->v_usecount == 0,
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("getnewvnode: free vnode isn't"));
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TAILQ_REMOVE(&vnode_free_list, vp, v_freelist);
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/* Don't recycle if we can't get the interlock */
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if (!mtx_trylock(&vp->v_interlock)) {
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vp = NULL;
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continue;
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}
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/* We should be able to immediately acquire this */
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if (vn_lock(vp, LK_INTERLOCK | LK_EXCLUSIVE, td) != 0)
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continue;
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/*
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* Don't recycle if we still have cached pages.
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* We have to drop the free list mtx to avoid lock
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* order reversals with interlock.
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*/
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if (VOP_GETVOBJECT(vp, &object) == 0 &&
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(object->resident_page_count ||
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object->ref_count)) {
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TAILQ_INSERT_TAIL(&vnode_free_list, vp,
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v_freelist);
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VOP_UNLOCK(vp, 0, td);
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vp = NULL;
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continue;
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}
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if (LIST_FIRST(&vp->v_cache_src)) {
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/*
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* note: nameileafonly sysctl is temporary,
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* for debugging only, and will eventually be
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* removed.
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*/
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if (nameileafonly > 0) {
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/*
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* Do not reuse namei-cached directory
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* vnodes that have cached
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* subdirectories.
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*/
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if (cache_leaf_test(vp) < 0) {
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VOP_UNLOCK(vp, 0, td);
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TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
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vp = NULL;
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continue;
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}
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} else if (nameileafonly < 0 ||
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vmiodirenable == 0) {
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/*
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* Do not reuse namei-cached directory
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* vnodes if nameileafonly is -1 or
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* if VMIO backing for directories is
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* turned off (otherwise we reuse them
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* too quickly).
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*/
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VOP_UNLOCK(vp, 0, td);
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TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
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vp = NULL;
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continue;
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}
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}
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mtx_unlock(&vnode_free_list_mtx);
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error = vcanrecycle(vp);
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/*
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* Skip over it if its filesystem is being suspended.
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*/
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if (vn_start_write(vp, &vnmp, V_NOWAIT) == 0)
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if (error == 0 &&
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vn_start_write(vp, &vnmp, V_NOWAIT) != 0)
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error = EBUSY;
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mtx_lock(&vnode_free_list_mtx);
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if (error != 0)
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TAILQ_INSERT_TAIL(&vnode_free_list, vp,
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v_freelist);
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else
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break;
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VOP_UNLOCK(vp, 0, td);
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TAILQ_INSERT_TAIL(&vnode_free_list, vp, v_freelist);
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vp = NULL;
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}
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}
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/*
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* Unlocked access to this vp is ok because we are assured that there
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* are no other references to it.
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*/
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if (vp) {
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mp_fixme("Unlocked v_iflags access.\n");
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vp->v_iflag |= VI_DOOMED;
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vp->v_iflag &= ~VI_FREE;
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freevnodes--;
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mtx_unlock(&vnode_free_list_mtx);
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vp->v_iflag |= VI_DOOMED;
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vp->v_iflag &= ~VI_FREE;
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cache_purge(vp);
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if (vp->v_type != VBAD) {
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VOP_UNLOCK(vp, 0, td);
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@ -785,16 +813,14 @@ getnewvnode(tag, mp, vops, vpp)
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#ifdef INVARIANTS
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{
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int s;
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if (vp->v_data)
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panic("cleaned vnode isn't");
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s = splbio();
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VI_LOCK(vp);
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if (vp->v_numoutput)
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panic("Clean vnode has pending I/O's");
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splx(s);
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if (vp->v_writecount != 0)
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panic("Non-zero write count");
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VI_UNLOCK(vp);
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}
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#endif
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if (vp->v_pollinfo) {
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@ -815,15 +841,15 @@ getnewvnode(tag, mp, vops, vpp)
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KASSERT(vp->v_cleanblkroot == NULL, ("cleanblkroot not NULL"));
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KASSERT(vp->v_dirtyblkroot == NULL, ("dirtyblkroot not NULL"));
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} else {
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numvnodes++;
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mtx_unlock(&vnode_free_list_mtx);
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vp = (struct vnode *) uma_zalloc(vnode_zone, M_WAITOK);
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bzero((char *) vp, sizeof *vp);
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vp = (struct vnode *) uma_zalloc(vnode_zone, M_WAITOK|M_ZERO);
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mtx_init(&vp->v_interlock, "vnode interlock", NULL, MTX_DEF);
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vp->v_dd = vp;
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cache_purge(vp);
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LIST_INIT(&vp->v_cache_src);
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TAILQ_INIT(&vp->v_cache_dst);
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numvnodes++;
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}
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TAILQ_INIT(&vp->v_cleanblkhd);
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