/* $NetBSD: nfs_kq.c,v 1.10 2006/05/14 21:32:21 elad 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. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * 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 __KERNEL_RCSID(0, "$NetBSD: nfs_kq.c,v 1.10 2006/05/14 21:32:21 elad Exp $"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include 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); static struct lock nfskevq_lock; static struct proc *pnfskq; static struct kevqlist kevlist = SLIST_HEAD_INITIALIZER(kevlist); void nfs_kqinit(void) { lockinit(&nfskevq_lock, PSOCK, "nfskqlck", 0, 0); } /* * 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 */ static void nfs_kqpoll(void *arg) { struct kevq *ke; struct vattr attr; struct proc *p = pnfskq; struct lwp *l = proc_representative_lwp(p); u_quad_t osize; for(;;) { lockmgr(&nfskevq_lock, LK_EXCLUSIVE, NULL); SLIST_FOREACH(ke, &kevlist, kev_link) { /* 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; lockmgr(&nfskevq_lock, LK_RELEASE, NULL); /* save v_size, nfs_getattr() updates it */ osize = ke->vp->v_size; (void) VOP_GETATTR(ke->vp, &attr, p->p_cred, l); /* following is a bit fragile, but about best * we can get */ if (attr.va_size != osize) { int extended = (attr.va_size > osize); VN_KNOTE(ke->vp, NOTE_WRITE | (extended ? NOTE_EXTEND : 0)); 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; } lockmgr(&nfskevq_lock, LK_EXCLUSIVE, NULL); 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; lockmgr(&nfskevq_lock, LK_RELEASE, NULL); kthread_exit(0); } lockmgr(&nfskevq_lock, LK_RELEASE, NULL); /* wait a while before checking for changes again */ tsleep(pnfskq, PSOCK, "nfskqpw", NFS_MINATTRTIMO * hz / 2); } } static void filt_nfsdetach(struct knote *kn) { struct vnode *vp = (struct vnode *)kn->kn_hook; struct kevq *ke; /* XXXLUKEM lock the struct? */ SLIST_REMOVE(&vp->v_klist, kn, knote, kn_selnext); /* Remove the vnode from watch list */ lockmgr(&nfskevq_lock, LK_EXCLUSIVE, NULL); SLIST_FOREACH(ke, &kevlist, kev_link) { if (ke->vp == vp) { while (ke->flags & KEVQ_BUSY) { ke->flags |= KEVQ_WANT; lockmgr(&nfskevq_lock, LK_RELEASE, NULL); (void) tsleep(ke, PSOCK, "nfskqdet", 0); lockmgr(&nfskevq_lock, LK_EXCLUSIVE, NULL); } 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; } } lockmgr(&nfskevq_lock, LK_RELEASE, NULL); } static int filt_nfsread(struct knote *kn, long hint) { struct vnode *vp = (struct vnode *)kn->kn_hook; /* * 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); } /* XXXLUKEM lock the struct? */ kn->kn_data = vp->v_size - kn->kn_fp->f_offset; return (kn->kn_data != 0); } static 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 /* { struct vnode *a_vp; struct knote *a_kn; } */ *ap = v; struct vnode *vp; struct knote *kn; struct kevq *ke; int error = 0; struct vattr attr; struct lwp *l = curlwp; /* XXX */ vp = ap->a_vp; kn = ap->a_kn; switch (kn->kn_filter) { case EVFILT_READ: kn->kn_fop = &nfsread_filtops; break; case EVFILT_VNODE: kn->kn_fop = &nfsvnode_filtops; break; default: return (1); } 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, l->l_proc->p_cred, l); lockmgr(&nfskevq_lock, LK_EXCLUSIVE, NULL); /* ensure the poller is running */ if (!pnfskq) { error = kthread_create1(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 */ MALLOC(ke, struct kevq *, 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); /* XXXLUKEM lock the struct? */ SLIST_INSERT_HEAD(&vp->v_klist, kn, kn_selnext); out: lockmgr(&nfskevq_lock, LK_RELEASE, NULL); return (error); }