1 /* $OpenBSD: nfs_kq.c,v 1.1 2004/07/21 17:30:56 marius Exp $ */
2 /* $NetBSD: nfs_kq.c,v 1.7 2003/10/30 01:43:10 simonb Exp $ */
3
4 /*-
5 * Copyright (c) 2002 The NetBSD Foundation, Inc.
6 * All rights reserved.
7 *
8 * This code is derived from software contributed to The NetBSD Foundation
9 * by Jaromir Dolecek.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. All advertising materials mentioning features or use of this software
20 * must display the following acknowledgement:
21 * This product includes software developed by the NetBSD
22 * Foundation, Inc. and its contributors.
23 * 4. Neither the name of The NetBSD Foundation nor the names of its
24 * contributors may be used to endorse or promote products derived
25 * from this software without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
28 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
29 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
30 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
31 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
32 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
33 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
34 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
35 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
36 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
37 * POSSIBILITY OF SUCH DAMAGE.
38 */
39
40 #include <sys/cdefs.h>
41 #ifdef __NetBSD__
42 __KERNEL_RCSID(0, "$NetBSD: nfs_kq.c,v 1.7 2003/10/30 01:43:10 simonb Exp $");
43 #endif /* __NetBSD__ */
44
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/kernel.h>
48 #include <sys/proc.h>
49 #include <sys/mount.h>
50 #include <sys/malloc.h>
51 #include <sys/vnode.h>
52 #include <sys/unistd.h>
53 #include <sys/file.h>
54 #include <sys/kthread.h>
55
56 #include <uvm/uvm_extern.h>
57 #include <uvm/uvm.h>
58
59 #include <nfs/rpcv2.h>
60 #include <nfs/nfsproto.h>
61 #include <nfs/nfs.h>
62 #include <nfs/nfsnode.h>
63 #include <nfs/nfs_var.h>
64
65 struct kevq {
66 SLIST_ENTRY(kevq) kev_link;
67 struct vnode *vp;
68 u_int usecount;
69 u_int flags;
70 #define KEVQ_BUSY 0x01 /* currently being processed */
71 #define KEVQ_WANT 0x02 /* want to change this entry */
72 struct timespec omtime; /* old modification time */
73 struct timespec octime; /* old change time */
74 nlink_t onlink; /* old number of references to file */
75 };
76 SLIST_HEAD(kevqlist, kevq);
77
78 static struct lock nfskevq_lock;
79 static struct proc *pnfskq;
80 static struct kevqlist kevlist = SLIST_HEAD_INITIALIZER(kevlist);
81
82 void
nfs_kqinit(void)83 nfs_kqinit(void)
84 {
85 lockinit(&nfskevq_lock, PSOCK, "nfskqlck", 0, 0);
86 }
87
88 /*
89 * This quite simplistic routine periodically checks for server changes
90 * of any of the watched files every NFS_MINATTRTIMO/2 seconds.
91 * Only changes in size, modification time, change time and nlinks
92 * are being checked, everything else is ignored.
93 * The routine only calls VOP_GETATTR() when it's likely it would get
94 * some new data, i.e. when the vnode expires from attrcache. This
95 * should give same result as periodically running stat(2) from userland,
96 * while keeping CPU/network usage low, and still provide proper kevent
97 * semantics.
98 * The poller thread is created when first vnode is added to watch list,
99 * and exits when the watch list is empty. The overhead of thread creation
100 * isn't really important, neither speed of attach and detach of knote.
101 */
102 /* ARGSUSED */
103 static void
nfs_kqpoll(void * arg)104 nfs_kqpoll(void *arg)
105 {
106 struct kevq *ke;
107 struct vattr attr;
108 struct proc *p = pnfskq;
109 u_quad_t osize;
110
111 for(;;) {
112 lockmgr(&nfskevq_lock, LK_EXCLUSIVE, NULL, p);
113 SLIST_FOREACH(ke, &kevlist, kev_link) {
114 struct nfsnode *np = VTONFS(ke->vp);
115
116 #ifdef DEBUG
117 printf("nfs_kqpoll on: ");
118 VOP_PRINT(ke->vp);
119 #endif
120 /* skip if still in attrcache */
121 if (nfs_getattrcache(ke->vp, &attr) != ENOENT)
122 continue;
123
124 /*
125 * Mark entry busy, release lock and check
126 * for changes.
127 */
128 ke->flags |= KEVQ_BUSY;
129 lockmgr(&nfskevq_lock, LK_RELEASE, NULL, p);
130
131 /* save v_size, nfs_getattr() updates it */
132 osize = np->n_size;
133
134 (void) VOP_GETATTR(ke->vp, &attr, p->p_ucred, p);
135
136 /* following is a bit fragile, but about best
137 * we can get */
138 if (attr.va_size != osize) {
139 int extended = (attr.va_size > osize);
140 VN_KNOTE(ke->vp, NOTE_WRITE
141 | (extended ? NOTE_EXTEND : 0));
142 ke->omtime = attr.va_mtime;
143 } else if (attr.va_mtime.tv_sec != ke->omtime.tv_sec
144 || attr.va_mtime.tv_nsec != ke->omtime.tv_nsec) {
145 VN_KNOTE(ke->vp, NOTE_WRITE);
146 ke->omtime = attr.va_mtime;
147 }
148
149 if (attr.va_ctime.tv_sec != ke->octime.tv_sec
150 || attr.va_ctime.tv_nsec != ke->octime.tv_nsec) {
151 VN_KNOTE(ke->vp, NOTE_ATTRIB);
152 ke->octime = attr.va_ctime;
153 }
154
155 if (attr.va_nlink != ke->onlink) {
156 VN_KNOTE(ke->vp, NOTE_LINK);
157 ke->onlink = attr.va_nlink;
158 }
159
160 lockmgr(&nfskevq_lock, LK_EXCLUSIVE, NULL, p);
161 ke->flags &= ~KEVQ_BUSY;
162 if (ke->flags & KEVQ_WANT) {
163 ke->flags &= ~KEVQ_WANT;
164 wakeup(ke);
165 }
166 }
167
168 if (SLIST_EMPTY(&kevlist)) {
169 /* Nothing more to watch, exit */
170 pnfskq = NULL;
171 lockmgr(&nfskevq_lock, LK_RELEASE, NULL, p);
172 kthread_exit(0);
173 }
174 lockmgr(&nfskevq_lock, LK_RELEASE, NULL, p);
175
176 /* wait a while before checking for changes again */
177 tsleep(pnfskq, PSOCK, "nfskqpw",
178 NFS_MINATTRTIMO * hz / 2);
179
180 }
181 }
182
183 static void
filt_nfsdetach(struct knote * kn)184 filt_nfsdetach(struct knote *kn)
185 {
186 struct vnode *vp = (struct vnode *)kn->kn_hook;
187 struct kevq *ke;
188 struct proc *p = curproc;
189
190 #ifdef notyet
191 /* XXXLUKEM lock the struct? */
192 SLIST_REMOVE(&vp->v_klist, kn, knote, kn_selnext);
193 #endif
194
195 simple_lock(&vp->v_selectinfo.vsi_lock);
196 SLIST_REMOVE(&vp->v_selectinfo.vsi_selinfo.si_note,
197 kn, knote, kn_selnext);
198 simple_unlock(&vp->v_selectinfo.vsi_lock);
199
200 /* Remove the vnode from watch list */
201 lockmgr(&nfskevq_lock, LK_EXCLUSIVE, NULL, p);
202 SLIST_FOREACH(ke, &kevlist, kev_link) {
203 if (ke->vp == vp) {
204 while (ke->flags & KEVQ_BUSY) {
205 ke->flags |= KEVQ_WANT;
206 lockmgr(&nfskevq_lock, LK_RELEASE, NULL, p);
207 (void) tsleep(ke, PSOCK, "nfskqdet", 0);
208 lockmgr(&nfskevq_lock, LK_EXCLUSIVE, NULL, p);
209 }
210
211 if (ke->usecount > 1) {
212 /* keep, other kevents need this */
213 ke->usecount--;
214 } else {
215 /* last user, g/c */
216 SLIST_REMOVE(&kevlist, ke, kevq, kev_link);
217 FREE(ke, M_KEVENT);
218 }
219 break;
220 }
221 }
222 lockmgr(&nfskevq_lock, LK_RELEASE, NULL, p);
223 }
224
225 static int
filt_nfsread(struct knote * kn,long hint)226 filt_nfsread(struct knote *kn, long hint)
227 {
228 struct vnode *vp = (struct vnode *)kn->kn_hook;
229 struct nfsnode *np = VTONFS(vp);
230
231 /*
232 * filesystem is gone, so set the EOF flag and schedule
233 * the knote for deletion.
234 */
235 if (hint == NOTE_REVOKE) {
236 kn->kn_flags |= (EV_EOF | EV_ONESHOT);
237 return (1);
238 }
239
240 /* XXXLUKEM lock the struct? */
241
242 kn->kn_data = np->n_size - kn->kn_fp->f_offset;
243 #ifdef DEBUG
244 printf("nfsread event. %d\n", kn->kn_data);
245 #endif
246 return (kn->kn_data != 0);
247 }
248
249 static int
filt_nfsvnode(struct knote * kn,long hint)250 filt_nfsvnode(struct knote *kn, long hint)
251 {
252 if (kn->kn_sfflags & hint)
253 kn->kn_fflags |= hint;
254 if (hint == NOTE_REVOKE) {
255 kn->kn_flags |= EV_EOF;
256 return (1);
257 }
258 return (kn->kn_fflags != 0);
259 }
260
261 static const struct filterops nfsread_filtops =
262 { 1, NULL, filt_nfsdetach, filt_nfsread };
263 static const struct filterops nfsvnode_filtops =
264 { 1, NULL, filt_nfsdetach, filt_nfsvnode };
265
266 int
nfs_kqfilter(void * v)267 nfs_kqfilter(void *v)
268 {
269 struct vop_kqfilter_args /* {
270 struct vnode *a_vp;
271 struct knote *a_kn;
272 } */ *ap = v;
273 struct vnode *vp;
274 struct knote *kn;
275 struct kevq *ke;
276 int error = 0;
277 struct vattr attr;
278 struct proc *p = curproc; /* XXX */
279
280 vp = ap->a_vp;
281 kn = ap->a_kn;
282
283 #ifdef DEBUG
284 printf("nfs_kqfilter(%d) on: ", kn->kn_filter);
285 VOP_PRINT(vp);
286 #endif
287
288 switch (kn->kn_filter) {
289 case EVFILT_READ:
290 kn->kn_fop = &nfsread_filtops;
291 break;
292 case EVFILT_VNODE:
293 kn->kn_fop = &nfsvnode_filtops;
294 break;
295 default:
296 return (1);
297 }
298
299 kn->kn_hook = vp;
300
301 /*
302 * Put the vnode to watched list.
303 */
304
305 /*
306 * Fetch current attributes. It's only needed when the vnode
307 * is not watched yet, but we need to do this without lock
308 * held. This is likely cheap due to attrcache, so do it now.
309 */
310 memset(&attr, 0, sizeof(attr));
311 (void) VOP_GETATTR(vp, &attr, p->p_ucred, p);
312
313 lockmgr(&nfskevq_lock, LK_EXCLUSIVE, NULL, p);
314
315 /* ensure the poller is running */
316 if (!pnfskq) {
317 error = kthread_create(nfs_kqpoll, NULL, &pnfskq,
318 "nfskqpoll");
319 if (error)
320 goto out;
321 }
322
323 SLIST_FOREACH(ke, &kevlist, kev_link)
324 if (ke->vp == vp)
325 break;
326
327 if (ke) {
328 /* already watched, so just bump usecount */
329 ke->usecount++;
330 } else {
331 /* need a new one */
332 MALLOC(ke, struct kevq *,
333 sizeof(struct kevq), M_KEVENT, M_WAITOK);
334 ke->vp = vp;
335 ke->usecount = 1;
336 ke->flags = 0;
337 ke->omtime = attr.va_mtime;
338 ke->octime = attr.va_ctime;
339 ke->onlink = attr.va_nlink;
340 SLIST_INSERT_HEAD(&kevlist, ke, kev_link);
341 }
342
343 /* kick the poller */
344 wakeup(pnfskq);
345
346 simple_lock(&vp->v_selectinfo.vsi_lock);
347 SLIST_INSERT_HEAD(&vp->v_selectinfo.vsi_selinfo.si_note, kn, kn_selnext);
348 simple_unlock(&vp->v_selectinfo.vsi_lock);
349
350 #ifdef notyet
351 /* XXXLUKEM lock the struct? */
352 SLIST_INSERT_HEAD(&vp->v_klist, kn, kn_selnext);
353 #endif
354
355 out:
356 lockmgr(&nfskevq_lock, LK_RELEASE, NULL, p);
357
358 return (error);
359 }
360