1 | /* $NetBSD: nfs_kq.c,v 1.25 2011/10/24 11:43:30 hannken Exp $ */ |
2 | |
3 | /*- |
4 | * Copyright (c) 2002, 2008 The NetBSD Foundation, Inc. |
5 | * All rights reserved. |
6 | * |
7 | * This code is derived from software contributed to The NetBSD Foundation |
8 | * by Jaromir Dolecek. |
9 | * |
10 | * Redistribution and use in source and binary forms, with or without |
11 | * modification, are permitted provided that the following conditions |
12 | * are met: |
13 | * 1. Redistributions of source code must retain the above copyright |
14 | * notice, this list of conditions and the following disclaimer. |
15 | * 2. Redistributions in binary form must reproduce the above copyright |
16 | * notice, this list of conditions and the following disclaimer in the |
17 | * documentation and/or other materials provided with the distribution. |
18 | * |
19 | * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS |
20 | * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED |
21 | * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
22 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS |
23 | * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
24 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
25 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
26 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
27 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
28 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
29 | * POSSIBILITY OF SUCH DAMAGE. |
30 | */ |
31 | |
32 | #include <sys/cdefs.h> |
33 | __KERNEL_RCSID(0, "$NetBSD: nfs_kq.c,v 1.25 2011/10/24 11:43:30 hannken Exp $" ); |
34 | |
35 | #include <sys/param.h> |
36 | #include <sys/systm.h> |
37 | #include <sys/condvar.h> |
38 | #include <sys/kernel.h> |
39 | #include <sys/proc.h> |
40 | #include <sys/kmem.h> |
41 | #include <sys/mount.h> |
42 | #include <sys/mutex.h> |
43 | #include <sys/vnode.h> |
44 | #include <sys/unistd.h> |
45 | #include <sys/file.h> |
46 | #include <sys/kthread.h> |
47 | |
48 | #include <uvm/uvm_extern.h> |
49 | #include <uvm/uvm.h> |
50 | |
51 | #include <nfs/rpcv2.h> |
52 | #include <nfs/nfsproto.h> |
53 | #include <nfs/nfs.h> |
54 | #include <nfs/nfsnode.h> |
55 | #include <nfs/nfs_var.h> |
56 | |
57 | struct kevq { |
58 | SLIST_ENTRY(kevq) kev_link; |
59 | struct vnode *vp; |
60 | u_int usecount; |
61 | u_int flags; |
62 | #define KEVQ_BUSY 0x01 /* currently being processed */ |
63 | struct timespec omtime; /* old modification time */ |
64 | struct timespec octime; /* old change time */ |
65 | nlink_t onlink; /* old number of references to file */ |
66 | kcondvar_t cv; |
67 | }; |
68 | SLIST_HEAD(kevqlist, kevq); |
69 | |
70 | static kmutex_t nfskq_lock; |
71 | static struct lwp *nfskq_thread; |
72 | static kcondvar_t nfskq_cv; |
73 | static struct kevqlist kevlist = SLIST_HEAD_INITIALIZER(kevlist); |
74 | static bool nfskq_thread_exit; |
75 | |
76 | void |
77 | nfs_kqinit(void) |
78 | { |
79 | |
80 | mutex_init(&nfskq_lock, MUTEX_DEFAULT, IPL_NONE); |
81 | cv_init(&nfskq_cv, "nfskqpw" ); |
82 | } |
83 | |
84 | void |
85 | nfs_kqfini(void) |
86 | { |
87 | |
88 | if (nfskq_thread != NULL) { |
89 | mutex_enter(&nfskq_lock); |
90 | nfskq_thread_exit = true; |
91 | cv_broadcast(&nfskq_cv); |
92 | do { |
93 | cv_wait(&nfskq_cv, &nfskq_lock); |
94 | } while (nfskq_thread != NULL); |
95 | mutex_exit(&nfskq_lock); |
96 | } |
97 | mutex_destroy(&nfskq_lock); |
98 | cv_destroy(&nfskq_cv); |
99 | } |
100 | |
101 | /* |
102 | * This quite simplistic routine periodically checks for server changes |
103 | * of any of the watched files every NFS_MINATTRTIMO/2 seconds. |
104 | * Only changes in size, modification time, change time and nlinks |
105 | * are being checked, everything else is ignored. |
106 | * The routine only calls VOP_GETATTR() when it's likely it would get |
107 | * some new data, i.e. when the vnode expires from attrcache. This |
108 | * should give same result as periodically running stat(2) from userland, |
109 | * while keeping CPU/network usage low, and still provide proper kevent |
110 | * semantics. |
111 | * The poller thread is created when first vnode is added to watch list, |
112 | * and exits when the watch list is empty. The overhead of thread creation |
113 | * isn't really important, neither speed of attach and detach of knote. |
114 | */ |
115 | /* ARGSUSED */ |
116 | static void |
117 | nfs_kqpoll(void *arg) |
118 | { |
119 | struct kevq *ke; |
120 | struct vattr attr; |
121 | struct lwp *l = curlwp; |
122 | u_quad_t osize; |
123 | |
124 | mutex_enter(&nfskq_lock); |
125 | while (!nfskq_thread_exit) { |
126 | SLIST_FOREACH(ke, &kevlist, kev_link) { |
127 | /* skip if still in attrcache */ |
128 | if (nfs_getattrcache(ke->vp, &attr) != ENOENT) |
129 | continue; |
130 | |
131 | /* |
132 | * Mark entry busy, release lock and check |
133 | * for changes. |
134 | */ |
135 | ke->flags |= KEVQ_BUSY; |
136 | mutex_exit(&nfskq_lock); |
137 | |
138 | /* save v_size, nfs_getattr() updates it */ |
139 | osize = ke->vp->v_size; |
140 | |
141 | memset(&attr, 0, sizeof(attr)); |
142 | vn_lock(ke->vp, LK_SHARED | LK_RETRY); |
143 | (void) VOP_GETATTR(ke->vp, &attr, l->l_cred); |
144 | VOP_UNLOCK(ke->vp); |
145 | |
146 | /* following is a bit fragile, but about best |
147 | * we can get */ |
148 | if (attr.va_size != osize) { |
149 | int extended = (attr.va_size > osize); |
150 | VN_KNOTE(ke->vp, NOTE_WRITE |
151 | | (extended ? NOTE_EXTEND : 0)); |
152 | ke->omtime = attr.va_mtime; |
153 | } else if (attr.va_mtime.tv_sec != ke->omtime.tv_sec |
154 | || attr.va_mtime.tv_nsec != ke->omtime.tv_nsec) { |
155 | VN_KNOTE(ke->vp, NOTE_WRITE); |
156 | ke->omtime = attr.va_mtime; |
157 | } |
158 | |
159 | if (attr.va_ctime.tv_sec != ke->octime.tv_sec |
160 | || attr.va_ctime.tv_nsec != ke->octime.tv_nsec) { |
161 | VN_KNOTE(ke->vp, NOTE_ATTRIB); |
162 | ke->octime = attr.va_ctime; |
163 | } |
164 | |
165 | if (attr.va_nlink != ke->onlink) { |
166 | VN_KNOTE(ke->vp, NOTE_LINK); |
167 | ke->onlink = attr.va_nlink; |
168 | } |
169 | |
170 | mutex_enter(&nfskq_lock); |
171 | ke->flags &= ~KEVQ_BUSY; |
172 | cv_signal(&ke->cv); |
173 | } |
174 | |
175 | if (SLIST_EMPTY(&kevlist)) { |
176 | /* Nothing more to watch, exit */ |
177 | nfskq_thread = NULL; |
178 | mutex_exit(&nfskq_lock); |
179 | kthread_exit(0); |
180 | } |
181 | |
182 | /* wait a while before checking for changes again */ |
183 | cv_timedwait(&nfskq_cv, &nfskq_lock, |
184 | NFS_MINATTRTIMO * hz / 2); |
185 | } |
186 | nfskq_thread = NULL; |
187 | cv_broadcast(&nfskq_cv); |
188 | mutex_exit(&nfskq_lock); |
189 | } |
190 | |
191 | static void |
192 | filt_nfsdetach(struct knote *kn) |
193 | { |
194 | struct vnode *vp = (struct vnode *)kn->kn_hook; |
195 | struct kevq *ke; |
196 | |
197 | mutex_enter(vp->v_interlock); |
198 | SLIST_REMOVE(&vp->v_klist, kn, knote, kn_selnext); |
199 | mutex_exit(vp->v_interlock); |
200 | |
201 | /* Remove the vnode from watch list */ |
202 | mutex_enter(&nfskq_lock); |
203 | SLIST_FOREACH(ke, &kevlist, kev_link) { |
204 | if (ke->vp == vp) { |
205 | while (ke->flags & KEVQ_BUSY) { |
206 | cv_wait(&ke->cv, &nfskq_lock); |
207 | } |
208 | |
209 | if (ke->usecount > 1) { |
210 | /* keep, other kevents need this */ |
211 | ke->usecount--; |
212 | } else { |
213 | /* last user, g/c */ |
214 | cv_destroy(&ke->cv); |
215 | SLIST_REMOVE(&kevlist, ke, kevq, kev_link); |
216 | kmem_free(ke, sizeof(*ke)); |
217 | } |
218 | break; |
219 | } |
220 | } |
221 | mutex_exit(&nfskq_lock); |
222 | } |
223 | |
224 | static int |
225 | filt_nfsread(struct knote *kn, long hint) |
226 | { |
227 | struct vnode *vp = (struct vnode *)kn->kn_hook; |
228 | int rv; |
229 | |
230 | /* |
231 | * filesystem is gone, so set the EOF flag and schedule |
232 | * the knote for deletion. |
233 | */ |
234 | switch (hint) { |
235 | case NOTE_REVOKE: |
236 | KASSERT(mutex_owned(vp->v_interlock)); |
237 | kn->kn_flags |= (EV_EOF | EV_ONESHOT); |
238 | return (1); |
239 | case 0: |
240 | mutex_enter(vp->v_interlock); |
241 | kn->kn_data = vp->v_size - ((file_t *)kn->kn_obj)->f_offset; |
242 | rv = (kn->kn_data != 0); |
243 | mutex_exit(vp->v_interlock); |
244 | return rv; |
245 | default: |
246 | KASSERT(mutex_owned(vp->v_interlock)); |
247 | kn->kn_data = vp->v_size - ((file_t *)kn->kn_obj)->f_offset; |
248 | return (kn->kn_data != 0); |
249 | } |
250 | } |
251 | |
252 | static int |
253 | filt_nfsvnode(struct knote *kn, long hint) |
254 | { |
255 | struct vnode *vp = (struct vnode *)kn->kn_hook; |
256 | int fflags; |
257 | |
258 | switch (hint) { |
259 | case NOTE_REVOKE: |
260 | KASSERT(mutex_owned(vp->v_interlock)); |
261 | kn->kn_flags |= EV_EOF; |
262 | if ((kn->kn_sfflags & hint) != 0) |
263 | kn->kn_fflags |= hint; |
264 | return (1); |
265 | case 0: |
266 | mutex_enter(vp->v_interlock); |
267 | fflags = kn->kn_fflags; |
268 | mutex_exit(vp->v_interlock); |
269 | break; |
270 | default: |
271 | KASSERT(mutex_owned(vp->v_interlock)); |
272 | if ((kn->kn_sfflags & hint) != 0) |
273 | kn->kn_fflags |= hint; |
274 | fflags = kn->kn_fflags; |
275 | break; |
276 | } |
277 | |
278 | return (fflags != 0); |
279 | } |
280 | |
281 | |
282 | static const struct filterops nfsread_filtops = |
283 | { 1, NULL, filt_nfsdetach, filt_nfsread }; |
284 | static const struct filterops nfsvnode_filtops = |
285 | { 1, NULL, filt_nfsdetach, filt_nfsvnode }; |
286 | |
287 | int |
288 | nfs_kqfilter(void *v) |
289 | { |
290 | struct vop_kqfilter_args /* { |
291 | struct vnode *a_vp; |
292 | struct knote *a_kn; |
293 | } */ *ap = v; |
294 | struct vnode *vp; |
295 | struct knote *kn; |
296 | struct kevq *ke; |
297 | int error = 0; |
298 | struct vattr attr; |
299 | struct lwp *l = curlwp; |
300 | |
301 | vp = ap->a_vp; |
302 | kn = ap->a_kn; |
303 | switch (kn->kn_filter) { |
304 | case EVFILT_READ: |
305 | kn->kn_fop = &nfsread_filtops; |
306 | break; |
307 | case EVFILT_VNODE: |
308 | kn->kn_fop = &nfsvnode_filtops; |
309 | break; |
310 | default: |
311 | return (EINVAL); |
312 | } |
313 | |
314 | /* |
315 | * Put the vnode to watched list. |
316 | */ |
317 | |
318 | /* |
319 | * Fetch current attributes. It's only needed when the vnode |
320 | * is not watched yet, but we need to do this without lock |
321 | * held. This is likely cheap due to attrcache, so do it now. |
322 | */ |
323 | memset(&attr, 0, sizeof(attr)); |
324 | vn_lock(vp, LK_SHARED | LK_RETRY); |
325 | (void) VOP_GETATTR(vp, &attr, l->l_cred); |
326 | VOP_UNLOCK(vp); |
327 | |
328 | mutex_enter(&nfskq_lock); |
329 | |
330 | /* ensure the poller is running */ |
331 | if (!nfskq_thread) { |
332 | error = kthread_create(PRI_NONE, 0, NULL, nfs_kqpoll, |
333 | NULL, &nfskq_thread, "nfskqpoll" ); |
334 | if (error) { |
335 | mutex_exit(&nfskq_lock); |
336 | return error; |
337 | } |
338 | } |
339 | |
340 | SLIST_FOREACH(ke, &kevlist, kev_link) { |
341 | if (ke->vp == vp) |
342 | break; |
343 | } |
344 | |
345 | if (ke) { |
346 | /* already watched, so just bump usecount */ |
347 | ke->usecount++; |
348 | } else { |
349 | /* need a new one */ |
350 | ke = kmem_alloc(sizeof(*ke), KM_SLEEP); |
351 | ke->vp = vp; |
352 | ke->usecount = 1; |
353 | ke->flags = 0; |
354 | ke->omtime = attr.va_mtime; |
355 | ke->octime = attr.va_ctime; |
356 | ke->onlink = attr.va_nlink; |
357 | cv_init(&ke->cv, "nfskqdet" ); |
358 | SLIST_INSERT_HEAD(&kevlist, ke, kev_link); |
359 | } |
360 | |
361 | mutex_enter(vp->v_interlock); |
362 | SLIST_INSERT_HEAD(&vp->v_klist, kn, kn_selnext); |
363 | kn->kn_hook = vp; |
364 | mutex_exit(vp->v_interlock); |
365 | |
366 | /* kick the poller */ |
367 | cv_signal(&nfskq_cv); |
368 | mutex_exit(&nfskq_lock); |
369 | |
370 | return (error); |
371 | } |
372 | |