vfs: add vrefact, to be used when the vnode has to be already active
This allows blind increment of relevant counters which under contention is cheaper than inc-not-zero loops at least on amd64. Use it in some of the places which are guaranteed to see already active vnodes. Reviewed by: kib (previous version)
This commit is contained in:
mjg
parent
f24a1f7d0d
commit
f03b37f3e8
@ -318,11 +318,11 @@ pwd_ensure_dirs(void)
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FILEDESC_XLOCK(fdp);
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if (fdp->fd_cdir == NULL) {
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fdp->fd_cdir = rootvnode;
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VREF(rootvnode);
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vrefact(rootvnode);
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}
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if (fdp->fd_rdir == NULL) {
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fdp->fd_rdir = rootvnode;
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VREF(rootvnode);
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vrefact(rootvnode);
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}
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FILEDESC_XUNLOCK(fdp);
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}
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@ -1860,13 +1860,13 @@ fdinit(struct filedesc *fdp, bool prepfiles)
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FILEDESC_SLOCK(fdp);
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newfdp->fd_cdir = fdp->fd_cdir;
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if (newfdp->fd_cdir)
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VREF(newfdp->fd_cdir);
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vrefact(newfdp->fd_cdir);
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newfdp->fd_rdir = fdp->fd_rdir;
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if (newfdp->fd_rdir)
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VREF(newfdp->fd_rdir);
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vrefact(newfdp->fd_rdir);
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newfdp->fd_jdir = fdp->fd_jdir;
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if (newfdp->fd_jdir)
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VREF(newfdp->fd_jdir);
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vrefact(newfdp->fd_jdir);
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if (!prepfiles) {
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FILEDESC_SUNLOCK(fdp);
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@ -2769,7 +2769,7 @@ _fgetvp(struct thread *td, int fd, int flags, cap_rights_t *needrightsp,
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error = EINVAL;
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} else {
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*vpp = fp->f_vnode;
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vref(*vpp);
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vrefact(*vpp);
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}
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fdrop(fp, td);
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@ -2807,7 +2807,7 @@ fgetvp_rights(struct thread *td, int fd, cap_rights_t *needrightsp,
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*havecaps = caps;
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*vpp = fp->f_vnode;
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vref(*vpp);
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vrefact(*vpp);
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return (0);
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out:
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@ -3115,10 +3115,10 @@ pwd_chroot(struct thread *td, struct vnode *vp)
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}
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}
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oldvp = fdp->fd_rdir;
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VREF(vp);
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vrefact(vp);
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fdp->fd_rdir = vp;
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if (fdp->fd_jdir == NULL) {
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VREF(vp);
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vrefact(vp);
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fdp->fd_jdir = vp;
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}
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FILEDESC_XUNLOCK(fdp);
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@ -3166,17 +3166,17 @@ mountcheckdirs(struct vnode *olddp, struct vnode *newdp)
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continue;
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FILEDESC_XLOCK(fdp);
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if (fdp->fd_cdir == olddp) {
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vref(newdp);
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vrefact(newdp);
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fdp->fd_cdir = newdp;
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nrele++;
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}
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if (fdp->fd_rdir == olddp) {
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vref(newdp);
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vrefact(newdp);
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fdp->fd_rdir = newdp;
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nrele++;
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}
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if (fdp->fd_jdir == olddp) {
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vref(newdp);
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vrefact(newdp);
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fdp->fd_jdir = newdp;
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nrele++;
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}
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@ -3185,13 +3185,13 @@ mountcheckdirs(struct vnode *olddp, struct vnode *newdp)
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}
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sx_sunlock(&allproc_lock);
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if (rootvnode == olddp) {
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vref(newdp);
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vrefact(newdp);
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rootvnode = newdp;
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nrele++;
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}
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mtx_lock(&prison0.pr_mtx);
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if (prison0.pr_root == olddp) {
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vref(newdp);
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vrefact(newdp);
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prison0.pr_root = newdp;
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nrele++;
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}
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@ -3200,7 +3200,7 @@ mountcheckdirs(struct vnode *olddp, struct vnode *newdp)
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TAILQ_FOREACH(pr, &allprison, pr_list) {
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mtx_lock(&pr->pr_mtx);
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if (pr->pr_root == olddp) {
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vref(newdp);
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vrefact(newdp);
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pr->pr_root = newdp;
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nrele++;
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}
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@ -3527,17 +3527,17 @@ kern_proc_filedesc_out(struct proc *p, struct sbuf *sb, ssize_t maxlen,
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/* ktrace vnode */
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tracevp = p->p_tracevp;
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if (tracevp != NULL)
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vref(tracevp);
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vrefact(tracevp);
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/* text vnode */
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textvp = p->p_textvp;
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if (textvp != NULL)
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vref(textvp);
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vrefact(textvp);
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/* Controlling tty. */
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cttyvp = NULL;
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if (p->p_pgrp != NULL && p->p_pgrp->pg_session != NULL) {
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cttyvp = p->p_pgrp->pg_session->s_ttyvp;
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if (cttyvp != NULL)
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vref(cttyvp);
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vrefact(cttyvp);
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}
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fdp = fdhold(p);
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PROC_UNLOCK(p);
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@ -3561,17 +3561,17 @@ kern_proc_filedesc_out(struct proc *p, struct sbuf *sb, ssize_t maxlen,
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FILEDESC_SLOCK(fdp);
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/* working directory */
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if (fdp->fd_cdir != NULL) {
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vref(fdp->fd_cdir);
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vrefact(fdp->fd_cdir);
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export_vnode_to_sb(fdp->fd_cdir, KF_FD_TYPE_CWD, FREAD, efbuf);
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}
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/* root directory */
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if (fdp->fd_rdir != NULL) {
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vref(fdp->fd_rdir);
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vrefact(fdp->fd_rdir);
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export_vnode_to_sb(fdp->fd_rdir, KF_FD_TYPE_ROOT, FREAD, efbuf);
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}
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/* jail directory */
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if (fdp->fd_jdir != NULL) {
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vref(fdp->fd_jdir);
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vrefact(fdp->fd_jdir);
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export_vnode_to_sb(fdp->fd_jdir, KF_FD_TYPE_JAIL, FREAD, efbuf);
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}
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for (i = 0; fdp->fd_refcnt > 0 && i <= fdp->fd_lastfile; i++) {
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@ -3661,7 +3661,7 @@ export_vnode_for_osysctl(struct vnode *vp, int type, struct kinfo_file *kif,
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{
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int error;
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vref(vp);
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vrefact(vp);
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FILEDESC_SUNLOCK(fdp);
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export_vnode_to_kinfo(vp, type, 0, kif, KERN_FILEDESC_PACK_KINFO);
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kinfo_to_okinfo(kif, okif);
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@ -3788,7 +3788,7 @@ kern_proc_cwd_out(struct proc *p, struct sbuf *sb, ssize_t maxlen)
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if (fdp->fd_cdir == NULL)
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error = EINVAL;
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else {
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vref(fdp->fd_cdir);
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vrefact(fdp->fd_cdir);
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error = export_vnode_to_sb(fdp->fd_cdir, KF_FD_TYPE_CWD,
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FREAD, efbuf);
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}
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@ -547,7 +547,7 @@ do_fork(struct thread *td, struct fork_req *fr, struct proc *p2, struct thread *
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/* Bump references to the text vnode (for procfs). */
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if (p2->p_textvp)
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vref(p2->p_textvp);
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vrefact(p2->p_textvp);
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/*
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* Set up linkage for kernel based threading.
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@ -255,7 +255,7 @@ namei_handle_root(struct nameidata *ndp, struct vnode **dpp)
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ndp->ni_pathlen--;
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}
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*dpp = ndp->ni_rootdir;
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VREF(*dpp);
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vrefact(*dpp);
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return (0);
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}
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@ -376,7 +376,7 @@ namei(struct nameidata *ndp)
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*/
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FILEDESC_SLOCK(fdp);
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ndp->ni_rootdir = fdp->fd_rdir;
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VREF(ndp->ni_rootdir);
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vrefact(ndp->ni_rootdir);
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ndp->ni_topdir = fdp->fd_jdir;
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/*
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@ -398,7 +398,7 @@ namei(struct nameidata *ndp)
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startdir_used = 1;
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} else if (ndp->ni_dirfd == AT_FDCWD) {
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dp = fdp->fd_cdir;
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VREF(dp);
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vrefact(dp);
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} else {
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rights = ndp->ni_rightsneeded;
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cap_rights_set(&rights, CAP_LOOKUP);
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@ -956,7 +956,7 @@ lookup(struct nameidata *ndp)
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vput(ndp->ni_dvp);
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else
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vrele(ndp->ni_dvp);
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vref(vp_crossmp);
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vrefact(vp_crossmp);
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ndp->ni_dvp = vp_crossmp;
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error = VFS_ROOT(mp, compute_cn_lkflags(mp, cnp->cn_lkflags,
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cnp->cn_flags), &tdp);
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@ -2647,6 +2647,28 @@ vrefl(struct vnode *vp)
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v_incr_usecount_locked(vp);
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}
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void
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vrefact(struct vnode *vp)
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{
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CTR2(KTR_VFS, "%s: vp %p", __func__, vp);
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if (__predict_false(vp->v_type == VCHR)) {
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VNASSERT(vp->v_holdcnt > 0 && vp->v_usecount > 0, vp,
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("%s: wrong ref counts", __func__));
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vref(vp);
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return;
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}
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#ifdef INVARIANTS
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int old = atomic_fetchadd_int(&vp->v_holdcnt, 1);
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VNASSERT(old > 0, vp, ("%s: wrong hold count", __func__));
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old = atomic_fetchadd_int(&vp->v_usecount, 1);
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VNASSERT(old > 0, vp, ("%s: wrong use count", __func__));
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#else
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refcount_acquire(&vp->v_holdcnt);
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refcount_acquire(&vp->v_usecount);
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#endif
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}
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/*
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* Return reference count of a vnode.
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*
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@ -828,6 +828,7 @@ void vput(struct vnode *vp);
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void vrele(struct vnode *vp);
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void vref(struct vnode *vp);
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void vrefl(struct vnode *vp);
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void vrefact(struct vnode *vp);
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int vrefcnt(struct vnode *vp);
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void v_addpollinfo(struct vnode *vp);
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