/* $OpenBSD: nfs_kq.c,v 1.16 2012/12/05 23:20:23 deraadt Exp $ */ /* $NetBSD: nfs_kq.c,v 1.7 2003/10/30 01:43:10 simonb Exp $ */ /*- * Copyright (c) 2002 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jaromir Dolecek. * * 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. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include void nfs_kqpoll(void *); void filt_nfsdetach(struct knote *); int filt_nfsread(struct knote *, long); int filt_nfsvnode(struct knote *, long); struct kevq { SLIST_ENTRY(kevq) kev_link; struct vnode *vp; u_int usecount; u_int flags; #define KEVQ_BUSY 0x01 /* currently being processed */ #define KEVQ_WANT 0x02 /* want to change this entry */ struct timespec omtime; /* old modification time */ struct timespec octime; /* old change time */ nlink_t onlink; /* old number of references to file */ }; SLIST_HEAD(kevqlist, kevq); struct rwlock nfskevq_lock = RWLOCK_INITIALIZER("nfskqlk"); struct proc *pnfskq; struct kevqlist kevlist = SLIST_HEAD_INITIALIZER(kevlist); /* * This quite simplistic routine periodically checks for server changes * of any of the watched files every NFS_MINATTRTIMO/2 seconds. * Only changes in size, modification time, change time and nlinks * are being checked, everything else is ignored. * The routine only calls VOP_GETATTR() when it's likely it would get * some new data, i.e. when the vnode expires from attrcache. This * should give same result as periodically running stat(2) from userland, * while keeping CPU/network usage low, and still provide proper kevent * semantics. * The poller thread is created when first vnode is added to watch list, * and exits when the watch list is empty. The overhead of thread creation * isn't really important, neither speed of attach and detach of knote. */ /* ARGSUSED */ void nfs_kqpoll(void *arg) { struct kevq *ke; struct vattr attr; struct proc *p = pnfskq; u_quad_t osize; int error; for(;;) { rw_enter_write(&nfskevq_lock); SLIST_FOREACH(ke, &kevlist, kev_link) { struct nfsnode *np = VTONFS(ke->vp); #ifdef DEBUG printf("nfs_kqpoll on: "); VOP_PRINT(ke->vp); #endif /* skip if still in attrcache */ if (nfs_getattrcache(ke->vp, &attr) != ENOENT) continue; /* * Mark entry busy, release lock and check * for changes. */ ke->flags |= KEVQ_BUSY; rw_exit_write(&nfskevq_lock); /* save v_size, nfs_getattr() updates it */ osize = np->n_size; error = VOP_GETATTR(ke->vp, &attr, p->p_ucred, p); if (error == ESTALE) { NFS_INVALIDATE_ATTRCACHE(np); VN_KNOTE(ke->vp, NOTE_DELETE); goto next; } /* following is a bit fragile, but about best * we can get */ if (attr.va_size != osize) { int flags = NOTE_WRITE; if (attr.va_size > osize) flags |= NOTE_EXTEND; else flags |= NOTE_TRUNCATE; VN_KNOTE(ke->vp, flags); ke->omtime = attr.va_mtime; } else if (attr.va_mtime.tv_sec != ke->omtime.tv_sec || attr.va_mtime.tv_nsec != ke->omtime.tv_nsec) { VN_KNOTE(ke->vp, NOTE_WRITE); ke->omtime = attr.va_mtime; } if (attr.va_ctime.tv_sec != ke->octime.tv_sec || attr.va_ctime.tv_nsec != ke->octime.tv_nsec) { VN_KNOTE(ke->vp, NOTE_ATTRIB); ke->octime = attr.va_ctime; } if (attr.va_nlink != ke->onlink) { VN_KNOTE(ke->vp, NOTE_LINK); ke->onlink = attr.va_nlink; } next: rw_enter_write(&nfskevq_lock); ke->flags &= ~KEVQ_BUSY; if (ke->flags & KEVQ_WANT) { ke->flags &= ~KEVQ_WANT; wakeup(ke); } } if (SLIST_EMPTY(&kevlist)) { /* Nothing more to watch, exit */ pnfskq = NULL; rw_exit_write(&nfskevq_lock); kthread_exit(0); } rw_exit_write(&nfskevq_lock); /* wait a while before checking for changes again */ tsleep(pnfskq, PSOCK, "nfskqpw", NFS_MINATTRTIMO * hz / 2); } } void filt_nfsdetach(struct knote *kn) { struct vnode *vp = (struct vnode *)kn->kn_hook; struct kevq *ke; SLIST_REMOVE(&vp->v_selectinfo.si_note, kn, knote, kn_selnext); /* Remove the vnode from watch list */ rw_enter_write(&nfskevq_lock); SLIST_FOREACH(ke, &kevlist, kev_link) { if (ke->vp == vp) { while (ke->flags & KEVQ_BUSY) { ke->flags |= KEVQ_WANT; rw_exit_write(&nfskevq_lock); (void) tsleep(ke, PSOCK, "nfskqdet", 0); rw_enter_write(&nfskevq_lock); } if (ke->usecount > 1) { /* keep, other kevents need this */ ke->usecount--; } else { /* last user, g/c */ SLIST_REMOVE(&kevlist, ke, kevq, kev_link); free(ke, M_KEVENT); } break; } } rw_exit_write(&nfskevq_lock); } int filt_nfsread(struct knote *kn, long hint) { struct vnode *vp = (struct vnode *)kn->kn_hook; struct nfsnode *np = VTONFS(vp); /* * filesystem is gone, so set the EOF flag and schedule * the knote for deletion. */ if (hint == NOTE_REVOKE) { kn->kn_flags |= (EV_EOF | EV_ONESHOT); return (1); } kn->kn_data = np->n_size - kn->kn_fp->f_offset; #ifdef DEBUG printf("nfsread event. %d\n", kn->kn_data); #endif return (kn->kn_data != 0); } int filt_nfsvnode(struct knote *kn, long hint) { if (kn->kn_sfflags & hint) kn->kn_fflags |= hint; if (hint == NOTE_REVOKE) { kn->kn_flags |= EV_EOF; return (1); } return (kn->kn_fflags != 0); } static const struct filterops nfsread_filtops = { 1, NULL, filt_nfsdetach, filt_nfsread }; static const struct filterops nfsvnode_filtops = { 1, NULL, filt_nfsdetach, filt_nfsvnode }; int nfs_kqfilter(void *v) { struct vop_kqfilter_args *ap = v; struct vnode *vp; struct knote *kn; struct kevq *ke; int error = 0; struct vattr attr; struct proc *p = curproc; /* XXX */ vp = ap->a_vp; kn = ap->a_kn; #ifdef DEBUG printf("nfs_kqfilter(%d) on: ", kn->kn_filter); VOP_PRINT(vp); #endif switch (kn->kn_filter) { case EVFILT_READ: kn->kn_fop = &nfsread_filtops; break; case EVFILT_VNODE: kn->kn_fop = &nfsvnode_filtops; break; default: return (EINVAL); } kn->kn_hook = vp; /* * Put the vnode to watched list. */ /* * Fetch current attributes. It's only needed when the vnode * is not watched yet, but we need to do this without lock * held. This is likely cheap due to attrcache, so do it now. */ memset(&attr, 0, sizeof(attr)); (void) VOP_GETATTR(vp, &attr, p->p_ucred, p); rw_enter_write(&nfskevq_lock); /* ensure the poller is running */ if (!pnfskq) { error = kthread_create(nfs_kqpoll, NULL, &pnfskq, "nfskqpoll"); if (error) goto out; } SLIST_FOREACH(ke, &kevlist, kev_link) if (ke->vp == vp) break; if (ke) { /* already watched, so just bump usecount */ ke->usecount++; } else { /* need a new one */ ke = malloc(sizeof(struct kevq), M_KEVENT, M_WAITOK); ke->vp = vp; ke->usecount = 1; ke->flags = 0; ke->omtime = attr.va_mtime; ke->octime = attr.va_ctime; ke->onlink = attr.va_nlink; SLIST_INSERT_HEAD(&kevlist, ke, kev_link); } /* kick the poller */ wakeup(pnfskq); SLIST_INSERT_HEAD(&vp->v_selectinfo.si_note, kn, kn_selnext); out: rw_exit_write(&nfskevq_lock); return (error); }