fss.c revision 1.85 1 /* $NetBSD: fss.c,v 1.85 2013/02/06 09:33:16 hannken Exp $ */
2
3 /*-
4 * Copyright (c) 2003 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Juergen Hannken-Illjes.
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 /*
33 * File system snapshot disk driver.
34 *
35 * Block/character interface to the snapshot of a mounted file system.
36 */
37
38 #include <sys/cdefs.h>
39 __KERNEL_RCSID(0, "$NetBSD: fss.c,v 1.85 2013/02/06 09:33:16 hannken Exp $");
40
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/namei.h>
44 #include <sys/proc.h>
45 #include <sys/errno.h>
46 #include <sys/malloc.h>
47 #include <sys/buf.h>
48 #include <sys/ioctl.h>
49 #include <sys/disklabel.h>
50 #include <sys/device.h>
51 #include <sys/disk.h>
52 #include <sys/stat.h>
53 #include <sys/mount.h>
54 #include <sys/vnode.h>
55 #include <sys/file.h>
56 #include <sys/uio.h>
57 #include <sys/conf.h>
58 #include <sys/kthread.h>
59 #include <sys/fstrans.h>
60 #include <sys/simplelock.h>
61 #include <sys/vfs_syscalls.h> /* For do_sys_unlink(). */
62
63 #include <miscfs/specfs/specdev.h>
64
65 #include <dev/fssvar.h>
66
67 #include <uvm/uvm.h>
68
69 void fssattach(int);
70
71 dev_type_open(fss_open);
72 dev_type_close(fss_close);
73 dev_type_read(fss_read);
74 dev_type_write(fss_write);
75 dev_type_ioctl(fss_ioctl);
76 dev_type_strategy(fss_strategy);
77 dev_type_dump(fss_dump);
78 dev_type_size(fss_size);
79
80 static void fss_unmount_hook(struct mount *);
81 static int fss_copy_on_write(void *, struct buf *, bool);
82 static inline void fss_error(struct fss_softc *, const char *);
83 static int fss_create_files(struct fss_softc *, struct fss_set *,
84 off_t *, struct lwp *);
85 static int fss_create_snapshot(struct fss_softc *, struct fss_set *,
86 struct lwp *);
87 static int fss_delete_snapshot(struct fss_softc *, struct lwp *);
88 static int fss_softc_alloc(struct fss_softc *);
89 static void fss_softc_free(struct fss_softc *);
90 static int fss_read_cluster(struct fss_softc *, u_int32_t);
91 static void fss_bs_thread(void *);
92 static int fss_bs_io(struct fss_softc *, fss_io_type,
93 u_int32_t, off_t, int, void *);
94 static u_int32_t *fss_bs_indir(struct fss_softc *, u_int32_t);
95
96 static kmutex_t fss_device_lock; /* Protect all units. */
97 static int fss_num_attached = 0; /* Number of attached devices. */
98 static struct vfs_hooks fss_vfs_hooks = {
99 .vh_unmount = fss_unmount_hook
100 };
101
102 const struct bdevsw fss_bdevsw = {
103 fss_open, fss_close, fss_strategy, fss_ioctl,
104 fss_dump, fss_size, D_DISK | D_MPSAFE
105 };
106
107 const struct cdevsw fss_cdevsw = {
108 fss_open, fss_close, fss_read, fss_write, fss_ioctl,
109 nostop, notty, nopoll, nommap, nokqfilter, D_DISK | D_MPSAFE
110 };
111
112 static int fss_match(device_t, cfdata_t, void *);
113 static void fss_attach(device_t, device_t, void *);
114 static int fss_detach(device_t, int);
115
116 CFATTACH_DECL_NEW(fss, sizeof(struct fss_softc),
117 fss_match, fss_attach, fss_detach, NULL);
118 extern struct cfdriver fss_cd;
119
120 void
121 fssattach(int num)
122 {
123
124 mutex_init(&fss_device_lock, MUTEX_DEFAULT, IPL_NONE);
125 if (config_cfattach_attach(fss_cd.cd_name, &fss_ca))
126 aprint_error("%s: unable to register\n", fss_cd.cd_name);
127 }
128
129 static int
130 fss_match(device_t self, cfdata_t cfdata, void *aux)
131 {
132 return 1;
133 }
134
135 static void
136 fss_attach(device_t parent, device_t self, void *aux)
137 {
138 struct fss_softc *sc = device_private(self);
139
140 sc->sc_dev = self;
141 sc->sc_bdev = NODEV;
142 mutex_init(&sc->sc_slock, MUTEX_DEFAULT, IPL_NONE);
143 mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_NONE);
144 cv_init(&sc->sc_work_cv, "fssbs");
145 cv_init(&sc->sc_cache_cv, "cowwait");
146 bufq_alloc(&sc->sc_bufq, "fcfs", 0);
147 sc->sc_dkdev = malloc(sizeof(*sc->sc_dkdev), M_DEVBUF, M_WAITOK);
148 sc->sc_dkdev->dk_info = NULL;
149 disk_init(sc->sc_dkdev, device_xname(self), NULL);
150 if (!pmf_device_register(self, NULL, NULL))
151 aprint_error_dev(self, "couldn't establish power handler\n");
152
153 if (fss_num_attached++ == 0)
154 vfs_hooks_attach(&fss_vfs_hooks);
155 }
156
157 static int
158 fss_detach(device_t self, int flags)
159 {
160 struct fss_softc *sc = device_private(self);
161
162 if (sc->sc_flags & FSS_ACTIVE)
163 return EBUSY;
164
165 if (--fss_num_attached == 0)
166 vfs_hooks_detach(&fss_vfs_hooks);
167
168 pmf_device_deregister(self);
169 mutex_destroy(&sc->sc_slock);
170 mutex_destroy(&sc->sc_lock);
171 cv_destroy(&sc->sc_work_cv);
172 cv_destroy(&sc->sc_cache_cv);
173 bufq_drain(sc->sc_bufq);
174 bufq_free(sc->sc_bufq);
175 disk_destroy(sc->sc_dkdev);
176 free(sc->sc_dkdev, M_DEVBUF);
177
178 return 0;
179 }
180
181 int
182 fss_open(dev_t dev, int flags, int mode, struct lwp *l)
183 {
184 int mflag;
185 cfdata_t cf;
186 struct fss_softc *sc;
187
188 mflag = (mode == S_IFCHR ? FSS_CDEV_OPEN : FSS_BDEV_OPEN);
189
190 mutex_enter(&fss_device_lock);
191
192 sc = device_lookup_private(&fss_cd, minor(dev));
193 if (sc == NULL) {
194 cf = malloc(sizeof(*cf), M_DEVBUF, M_WAITOK);
195 cf->cf_name = fss_cd.cd_name;
196 cf->cf_atname = fss_cd.cd_name;
197 cf->cf_unit = minor(dev);
198 cf->cf_fstate = FSTATE_STAR;
199 sc = device_private(config_attach_pseudo(cf));
200 if (sc == NULL) {
201 mutex_exit(&fss_device_lock);
202 return ENOMEM;
203 }
204 }
205
206 mutex_enter(&sc->sc_slock);
207
208 sc->sc_flags |= mflag;
209
210 mutex_exit(&sc->sc_slock);
211 mutex_exit(&fss_device_lock);
212
213 return 0;
214 }
215
216 int
217 fss_close(dev_t dev, int flags, int mode, struct lwp *l)
218 {
219 int mflag, error;
220 cfdata_t cf;
221 struct fss_softc *sc = device_lookup_private(&fss_cd, minor(dev));
222
223 mflag = (mode == S_IFCHR ? FSS_CDEV_OPEN : FSS_BDEV_OPEN);
224 error = 0;
225
226 mutex_enter(&fss_device_lock);
227 restart:
228 mutex_enter(&sc->sc_slock);
229 if ((sc->sc_flags & (FSS_CDEV_OPEN|FSS_BDEV_OPEN)) != mflag) {
230 sc->sc_flags &= ~mflag;
231 mutex_exit(&sc->sc_slock);
232 mutex_exit(&fss_device_lock);
233 return 0;
234 }
235 if ((sc->sc_flags & FSS_ACTIVE) != 0 &&
236 (sc->sc_uflags & FSS_UNCONFIG_ON_CLOSE) != 0) {
237 sc->sc_uflags &= ~FSS_UNCONFIG_ON_CLOSE;
238 mutex_exit(&sc->sc_slock);
239 error = fss_ioctl(dev, FSSIOCCLR, NULL, FWRITE, l);
240 goto restart;
241 }
242 if ((sc->sc_flags & FSS_ACTIVE) != 0) {
243 mutex_exit(&sc->sc_slock);
244 mutex_exit(&fss_device_lock);
245 return error;
246 }
247
248 KASSERT((sc->sc_flags & FSS_ACTIVE) == 0);
249 KASSERT((sc->sc_flags & (FSS_CDEV_OPEN|FSS_BDEV_OPEN)) == mflag);
250 mutex_exit(&sc->sc_slock);
251 cf = device_cfdata(sc->sc_dev);
252 error = config_detach(sc->sc_dev, DETACH_QUIET);
253 if (! error)
254 free(cf, M_DEVBUF);
255 mutex_exit(&fss_device_lock);
256
257 return error;
258 }
259
260 void
261 fss_strategy(struct buf *bp)
262 {
263 const bool write = ((bp->b_flags & B_READ) != B_READ);
264 struct fss_softc *sc = device_lookup_private(&fss_cd, minor(bp->b_dev));
265
266 mutex_enter(&sc->sc_slock);
267
268 if (write || !FSS_ISVALID(sc)) {
269
270 mutex_exit(&sc->sc_slock);
271
272 bp->b_error = (write ? EROFS : ENXIO);
273 bp->b_resid = bp->b_bcount;
274 biodone(bp);
275 return;
276 }
277
278 bp->b_rawblkno = bp->b_blkno;
279 bufq_put(sc->sc_bufq, bp);
280 cv_signal(&sc->sc_work_cv);
281
282 mutex_exit(&sc->sc_slock);
283 }
284
285 int
286 fss_read(dev_t dev, struct uio *uio, int flags)
287 {
288 return physio(fss_strategy, NULL, dev, B_READ, minphys, uio);
289 }
290
291 int
292 fss_write(dev_t dev, struct uio *uio, int flags)
293 {
294 return physio(fss_strategy, NULL, dev, B_WRITE, minphys, uio);
295 }
296
297 int
298 fss_ioctl(dev_t dev, u_long cmd, void *data, int flag, struct lwp *l)
299 {
300 int error;
301 struct fss_softc *sc = device_lookup_private(&fss_cd, minor(dev));
302 struct fss_set _fss;
303 struct fss_set *fss = (struct fss_set *)data;
304 struct fss_set50 *fss50 = (struct fss_set50 *)data;
305 struct fss_get *fsg = (struct fss_get *)data;
306 #ifndef _LP64
307 struct fss_get50 *fsg50 = (struct fss_get50 *)data;
308 #endif
309
310 switch (cmd) {
311 case FSSIOCSET50:
312 fss = &_fss;
313 fss->fss_mount = fss50->fss_mount;
314 fss->fss_bstore = fss50->fss_bstore;
315 fss->fss_csize = fss50->fss_csize;
316 fss->fss_flags = 0;
317 /* Fall through */
318 case FSSIOCSET:
319 mutex_enter(&sc->sc_lock);
320 if ((flag & FWRITE) == 0)
321 error = EPERM;
322 else if ((sc->sc_flags & FSS_ACTIVE) != 0)
323 error = EBUSY;
324 else
325 error = fss_create_snapshot(sc, fss, l);
326 if (error == 0)
327 sc->sc_uflags = fss->fss_flags;
328 mutex_exit(&sc->sc_lock);
329 break;
330
331 case FSSIOCCLR:
332 mutex_enter(&sc->sc_lock);
333 if ((flag & FWRITE) == 0)
334 error = EPERM;
335 else if ((sc->sc_flags & FSS_ACTIVE) == 0)
336 error = ENXIO;
337 else
338 error = fss_delete_snapshot(sc, l);
339 mutex_exit(&sc->sc_lock);
340 break;
341
342 #ifndef _LP64
343 case FSSIOCGET50:
344 mutex_enter(&sc->sc_lock);
345 switch (sc->sc_flags & (FSS_PERSISTENT | FSS_ACTIVE)) {
346 case FSS_ACTIVE:
347 memcpy(fsg50->fsg_mount, sc->sc_mntname, MNAMELEN);
348 fsg50->fsg_csize = FSS_CLSIZE(sc);
349 timeval_to_timeval50(&sc->sc_time, &fsg50->fsg_time);
350 fsg50->fsg_mount_size = sc->sc_clcount;
351 fsg50->fsg_bs_size = sc->sc_clnext;
352 error = 0;
353 break;
354 case FSS_PERSISTENT | FSS_ACTIVE:
355 memcpy(fsg50->fsg_mount, sc->sc_mntname, MNAMELEN);
356 fsg50->fsg_csize = 0;
357 timeval_to_timeval50(&sc->sc_time, &fsg50->fsg_time);
358 fsg50->fsg_mount_size = 0;
359 fsg50->fsg_bs_size = 0;
360 error = 0;
361 break;
362 default:
363 error = ENXIO;
364 break;
365 }
366 mutex_exit(&sc->sc_lock);
367 break;
368 #endif /* _LP64 */
369
370 case FSSIOCGET:
371 mutex_enter(&sc->sc_lock);
372 switch (sc->sc_flags & (FSS_PERSISTENT | FSS_ACTIVE)) {
373 case FSS_ACTIVE:
374 memcpy(fsg->fsg_mount, sc->sc_mntname, MNAMELEN);
375 fsg->fsg_csize = FSS_CLSIZE(sc);
376 fsg->fsg_time = sc->sc_time;
377 fsg->fsg_mount_size = sc->sc_clcount;
378 fsg->fsg_bs_size = sc->sc_clnext;
379 error = 0;
380 break;
381 case FSS_PERSISTENT | FSS_ACTIVE:
382 memcpy(fsg->fsg_mount, sc->sc_mntname, MNAMELEN);
383 fsg->fsg_csize = 0;
384 fsg->fsg_time = sc->sc_time;
385 fsg->fsg_mount_size = 0;
386 fsg->fsg_bs_size = 0;
387 error = 0;
388 break;
389 default:
390 error = ENXIO;
391 break;
392 }
393 mutex_exit(&sc->sc_lock);
394 break;
395
396 case FSSIOFSET:
397 mutex_enter(&sc->sc_slock);
398 sc->sc_uflags = *(int *)data;
399 mutex_exit(&sc->sc_slock);
400 error = 0;
401 break;
402
403 case FSSIOFGET:
404 mutex_enter(&sc->sc_slock);
405 *(int *)data = sc->sc_uflags;
406 mutex_exit(&sc->sc_slock);
407 error = 0;
408 break;
409
410 default:
411 error = EINVAL;
412 break;
413 }
414
415 return error;
416 }
417
418 int
419 fss_size(dev_t dev)
420 {
421 return -1;
422 }
423
424 int
425 fss_dump(dev_t dev, daddr_t blkno, void *va,
426 size_t size)
427 {
428 return EROFS;
429 }
430
431 /*
432 * An error occurred reading or writing the snapshot or backing store.
433 * If it is the first error log to console.
434 * The caller holds the mutex.
435 */
436 static inline void
437 fss_error(struct fss_softc *sc, const char *msg)
438 {
439
440 if ((sc->sc_flags & (FSS_ACTIVE|FSS_ERROR)) == FSS_ACTIVE)
441 aprint_error_dev(sc->sc_dev, "snapshot invalid: %s\n", msg);
442 if ((sc->sc_flags & FSS_ACTIVE) == FSS_ACTIVE)
443 sc->sc_flags |= FSS_ERROR;
444 }
445
446 /*
447 * Allocate the variable sized parts of the softc and
448 * fork the kernel thread.
449 *
450 * The fields sc_clcount, sc_clshift, sc_cache_size and sc_indir_size
451 * must be initialized.
452 */
453 static int
454 fss_softc_alloc(struct fss_softc *sc)
455 {
456 int i, error;
457
458 if ((sc->sc_flags & FSS_PERSISTENT) == 0) {
459 sc->sc_copied =
460 kmem_zalloc(howmany(sc->sc_clcount, NBBY), KM_SLEEP);
461 if (sc->sc_copied == NULL)
462 return(ENOMEM);
463
464 sc->sc_cache = kmem_alloc(sc->sc_cache_size *
465 sizeof(struct fss_cache), KM_SLEEP);
466 if (sc->sc_cache == NULL)
467 return(ENOMEM);
468
469 for (i = 0; i < sc->sc_cache_size; i++) {
470 sc->sc_cache[i].fc_type = FSS_CACHE_FREE;
471 sc->sc_cache[i].fc_data =
472 kmem_alloc(FSS_CLSIZE(sc), KM_SLEEP);
473 if (sc->sc_cache[i].fc_data == NULL)
474 return(ENOMEM);
475 cv_init(&sc->sc_cache[i].fc_state_cv, "cowwait1");
476 }
477
478 sc->sc_indir_valid =
479 kmem_zalloc(howmany(sc->sc_indir_size, NBBY), KM_SLEEP);
480 if (sc->sc_indir_valid == NULL)
481 return(ENOMEM);
482
483 sc->sc_indir_data = kmem_zalloc(FSS_CLSIZE(sc), KM_SLEEP);
484 if (sc->sc_indir_data == NULL)
485 return(ENOMEM);
486 } else {
487 sc->sc_copied = NULL;
488 sc->sc_cache = NULL;
489 sc->sc_indir_valid = NULL;
490 sc->sc_indir_data = NULL;
491 }
492
493 sc->sc_flags |= FSS_BS_THREAD;
494 if ((error = kthread_create(PRI_BIO, KTHREAD_MUSTJOIN, NULL,
495 fss_bs_thread, sc, &sc->sc_bs_lwp,
496 "%s", device_xname(sc->sc_dev))) != 0) {
497 sc->sc_flags &= ~FSS_BS_THREAD;
498 return error;
499 }
500
501 disk_attach(sc->sc_dkdev);
502
503 return 0;
504 }
505
506 /*
507 * Free the variable sized parts of the softc.
508 */
509 static void
510 fss_softc_free(struct fss_softc *sc)
511 {
512 int i;
513
514 if ((sc->sc_flags & FSS_BS_THREAD) != 0) {
515 mutex_enter(&sc->sc_slock);
516 sc->sc_flags &= ~FSS_BS_THREAD;
517 cv_signal(&sc->sc_work_cv);
518 mutex_exit(&sc->sc_slock);
519 kthread_join(sc->sc_bs_lwp);
520
521 disk_detach(sc->sc_dkdev);
522 }
523
524 if (sc->sc_copied != NULL)
525 kmem_free(sc->sc_copied, howmany(sc->sc_clcount, NBBY));
526 sc->sc_copied = NULL;
527
528 if (sc->sc_cache != NULL) {
529 for (i = 0; i < sc->sc_cache_size; i++)
530 if (sc->sc_cache[i].fc_data != NULL) {
531 cv_destroy(&sc->sc_cache[i].fc_state_cv);
532 kmem_free(sc->sc_cache[i].fc_data,
533 FSS_CLSIZE(sc));
534 }
535 kmem_free(sc->sc_cache,
536 sc->sc_cache_size*sizeof(struct fss_cache));
537 }
538 sc->sc_cache = NULL;
539
540 if (sc->sc_indir_valid != NULL)
541 kmem_free(sc->sc_indir_valid, howmany(sc->sc_indir_size, NBBY));
542 sc->sc_indir_valid = NULL;
543
544 if (sc->sc_indir_data != NULL)
545 kmem_free(sc->sc_indir_data, FSS_CLSIZE(sc));
546 sc->sc_indir_data = NULL;
547 }
548
549 /*
550 * Set all active snapshots on this file system into ERROR state.
551 */
552 static void
553 fss_unmount_hook(struct mount *mp)
554 {
555 int i;
556 struct fss_softc *sc;
557
558 mutex_enter(&fss_device_lock);
559 for (i = 0; i < fss_cd.cd_ndevs; i++) {
560 if ((sc = device_lookup_private(&fss_cd, i)) == NULL)
561 continue;
562 mutex_enter(&sc->sc_slock);
563 if ((sc->sc_flags & FSS_ACTIVE) != 0 &&
564 sc->sc_mount == mp)
565 fss_error(sc, "forced unmount");
566 mutex_exit(&sc->sc_slock);
567 }
568 mutex_exit(&fss_device_lock);
569 }
570
571 /*
572 * A buffer is written to the snapshotted block device. Copy to
573 * backing store if needed.
574 */
575 static int
576 fss_copy_on_write(void *v, struct buf *bp, bool data_valid)
577 {
578 int error;
579 u_int32_t cl, ch, c;
580 struct fss_softc *sc = v;
581
582 mutex_enter(&sc->sc_slock);
583 if (!FSS_ISVALID(sc)) {
584 mutex_exit(&sc->sc_slock);
585 return 0;
586 }
587
588 cl = FSS_BTOCL(sc, dbtob(bp->b_blkno));
589 ch = FSS_BTOCL(sc, dbtob(bp->b_blkno)+bp->b_bcount-1);
590 error = 0;
591 if (curlwp == uvm.pagedaemon_lwp) {
592 for (c = cl; c <= ch; c++)
593 if (isclr(sc->sc_copied, c)) {
594 error = ENOMEM;
595 break;
596 }
597 }
598 mutex_exit(&sc->sc_slock);
599
600 if (error == 0)
601 for (c = cl; c <= ch; c++) {
602 error = fss_read_cluster(sc, c);
603 if (error)
604 break;
605 }
606
607 return error;
608 }
609
610 /*
611 * Lookup and open needed files.
612 *
613 * For file system internal snapshot initializes sc_mntname, sc_mount,
614 * sc_bs_vp and sc_time.
615 *
616 * Otherwise returns dev and size of the underlying block device.
617 * Initializes sc_mntname, sc_mount, sc_bdev, sc_bs_vp and sc_mount
618 */
619 static int
620 fss_create_files(struct fss_softc *sc, struct fss_set *fss,
621 off_t *bsize, struct lwp *l)
622 {
623 int i, error, bits, fsbsize;
624 uint64_t numsec;
625 unsigned int secsize;
626 struct timespec ts;
627 /* nd -> nd2 to reduce mistakes while updating only some namei calls */
628 struct pathbuf *pb2;
629 struct nameidata nd2;
630 struct vnode *vp;
631
632 /*
633 * Get the mounted file system.
634 */
635
636 error = namei_simple_user(fss->fss_mount,
637 NSM_FOLLOW_NOEMULROOT, &vp);
638 if (error != 0)
639 return error;
640
641 if ((vp->v_vflag & VV_ROOT) != VV_ROOT) {
642 vrele(vp);
643 return EINVAL;
644 }
645
646 sc->sc_mount = vp->v_mount;
647 memcpy(sc->sc_mntname, sc->sc_mount->mnt_stat.f_mntonname, MNAMELEN);
648
649 vrele(vp);
650
651 /*
652 * Check for file system internal snapshot.
653 */
654
655 error = namei_simple_user(fss->fss_bstore,
656 NSM_FOLLOW_NOEMULROOT, &vp);
657 if (error != 0)
658 return error;
659
660 if (vp->v_type == VREG && vp->v_mount == sc->sc_mount) {
661 sc->sc_flags |= FSS_PERSISTENT;
662 sc->sc_bs_vp = vp;
663
664 fsbsize = sc->sc_bs_vp->v_mount->mnt_stat.f_iosize;
665 bits = sizeof(sc->sc_bs_bshift)*NBBY;
666 for (sc->sc_bs_bshift = 1; sc->sc_bs_bshift < bits;
667 sc->sc_bs_bshift++)
668 if (FSS_FSBSIZE(sc) == fsbsize)
669 break;
670 if (sc->sc_bs_bshift >= bits)
671 return EINVAL;
672
673 sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1;
674 sc->sc_clshift = 0;
675
676 if ((fss->fss_flags & FSS_UNLINK_ON_CREATE) != 0) {
677 error = do_sys_unlink(fss->fss_bstore, UIO_USERSPACE);
678 if (error)
679 return error;
680 }
681 error = vn_lock(vp, LK_EXCLUSIVE);
682 if (error != 0)
683 return error;
684 error = VFS_SNAPSHOT(sc->sc_mount, sc->sc_bs_vp, &ts);
685 TIMESPEC_TO_TIMEVAL(&sc->sc_time, &ts);
686
687 VOP_UNLOCK(sc->sc_bs_vp);
688
689 return error;
690 }
691 vrele(vp);
692
693 /*
694 * Get the block device it is mounted on and its size.
695 */
696
697 mutex_enter(&device_lock);
698 for (i = 0; i < SPECHSZ; i++) {
699 for (vp = specfs_hash[i]; vp; vp = vp->v_specnext) {
700 if (vp->v_type == VBLK &&
701 vp == vp->v_specnode->sn_dev->sd_bdevvp &&
702 vp->v_specmountpoint == sc->sc_mount)
703 break;
704 }
705 if (vp != NULL)
706 break;
707 }
708 if (vp == NULL) {
709 mutex_exit(&device_lock);
710 return EINVAL;
711 }
712 mutex_enter(vp->v_interlock);
713 mutex_exit(&device_lock);
714 error = vget(vp, 0);
715 if (error)
716 return error;
717 sc->sc_bdev = vp->v_rdev;
718
719 error = getdisksize(vp, &numsec, &secsize);
720 vrele(vp);
721 if (error)
722 return error;
723
724 *bsize = (off_t)numsec*secsize;
725
726 /*
727 * Get the backing store
728 */
729
730 error = pathbuf_copyin(fss->fss_bstore, &pb2);
731 if (error) {
732 return error;
733 }
734 NDINIT(&nd2, LOOKUP, FOLLOW, pb2);
735 if ((error = vn_open(&nd2, FREAD|FWRITE, 0)) != 0) {
736 pathbuf_destroy(pb2);
737 return error;
738 }
739 VOP_UNLOCK(nd2.ni_vp);
740
741 sc->sc_bs_vp = nd2.ni_vp;
742
743 if (nd2.ni_vp->v_type != VREG && nd2.ni_vp->v_type != VCHR) {
744 pathbuf_destroy(pb2);
745 return EINVAL;
746 }
747 pathbuf_destroy(pb2);
748
749 if ((fss->fss_flags & FSS_UNLINK_ON_CREATE) != 0) {
750 error = do_sys_unlink(fss->fss_bstore, UIO_USERSPACE);
751 if (error)
752 return error;
753 }
754 if (sc->sc_bs_vp->v_type == VREG) {
755 fsbsize = sc->sc_bs_vp->v_mount->mnt_stat.f_iosize;
756 if (fsbsize & (fsbsize-1)) /* No power of two */
757 return EINVAL;
758 for (sc->sc_bs_bshift = 1; sc->sc_bs_bshift < 32;
759 sc->sc_bs_bshift++)
760 if (FSS_FSBSIZE(sc) == fsbsize)
761 break;
762 if (sc->sc_bs_bshift >= 32)
763 return EINVAL;
764 sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1;
765 } else {
766 sc->sc_bs_bshift = DEV_BSHIFT;
767 sc->sc_bs_bmask = FSS_FSBSIZE(sc)-1;
768 }
769
770 return 0;
771 }
772
773 /*
774 * Create a snapshot.
775 */
776 static int
777 fss_create_snapshot(struct fss_softc *sc, struct fss_set *fss, struct lwp *l)
778 {
779 int len, error;
780 u_int32_t csize;
781 off_t bsize;
782
783 bsize = 0; /* XXX gcc */
784
785 /*
786 * Open needed files.
787 */
788 if ((error = fss_create_files(sc, fss, &bsize, l)) != 0)
789 goto bad;
790
791 if (sc->sc_flags & FSS_PERSISTENT) {
792 fss_softc_alloc(sc);
793 sc->sc_flags |= FSS_ACTIVE;
794 return 0;
795 }
796
797 /*
798 * Set cluster size. Must be a power of two and
799 * a multiple of backing store block size.
800 */
801 if (fss->fss_csize <= 0)
802 csize = MAXPHYS;
803 else
804 csize = fss->fss_csize;
805 if (bsize/csize > FSS_CLUSTER_MAX)
806 csize = bsize/FSS_CLUSTER_MAX+1;
807
808 for (sc->sc_clshift = sc->sc_bs_bshift; sc->sc_clshift < 32;
809 sc->sc_clshift++)
810 if (FSS_CLSIZE(sc) >= csize)
811 break;
812 if (sc->sc_clshift >= 32) {
813 error = EINVAL;
814 goto bad;
815 }
816 sc->sc_clmask = FSS_CLSIZE(sc)-1;
817
818 /*
819 * Set number of cache slots.
820 */
821 if (FSS_CLSIZE(sc) <= 8192)
822 sc->sc_cache_size = 32;
823 else if (FSS_CLSIZE(sc) <= 65536)
824 sc->sc_cache_size = 8;
825 else
826 sc->sc_cache_size = 4;
827
828 /*
829 * Set number of clusters and size of last cluster.
830 */
831 sc->sc_clcount = FSS_BTOCL(sc, bsize-1)+1;
832 sc->sc_clresid = FSS_CLOFF(sc, bsize-1)+1;
833
834 /*
835 * Set size of indirect table.
836 */
837 len = sc->sc_clcount*sizeof(u_int32_t);
838 sc->sc_indir_size = FSS_BTOCL(sc, len)+1;
839 sc->sc_clnext = sc->sc_indir_size;
840 sc->sc_indir_cur = 0;
841
842 if ((error = fss_softc_alloc(sc)) != 0)
843 goto bad;
844
845 /*
846 * Activate the snapshot.
847 */
848
849 if ((error = vfs_suspend(sc->sc_mount, 0)) != 0)
850 goto bad;
851
852 microtime(&sc->sc_time);
853
854 error = fscow_establish(sc->sc_mount, fss_copy_on_write, sc);
855 if (error == 0)
856 sc->sc_flags |= FSS_ACTIVE;
857
858 vfs_resume(sc->sc_mount);
859
860 if (error != 0)
861 goto bad;
862
863 aprint_debug_dev(sc->sc_dev, "%s snapshot active\n", sc->sc_mntname);
864 aprint_debug_dev(sc->sc_dev,
865 "%u clusters of %u, %u cache slots, %u indir clusters\n",
866 sc->sc_clcount, FSS_CLSIZE(sc),
867 sc->sc_cache_size, sc->sc_indir_size);
868
869 return 0;
870
871 bad:
872 fss_softc_free(sc);
873 if (sc->sc_bs_vp != NULL) {
874 if (sc->sc_flags & FSS_PERSISTENT)
875 vrele(sc->sc_bs_vp);
876 else
877 vn_close(sc->sc_bs_vp, FREAD|FWRITE, l->l_cred);
878 }
879 sc->sc_bs_vp = NULL;
880
881 return error;
882 }
883
884 /*
885 * Delete a snapshot.
886 */
887 static int
888 fss_delete_snapshot(struct fss_softc *sc, struct lwp *l)
889 {
890
891 if ((sc->sc_flags & FSS_PERSISTENT) == 0)
892 fscow_disestablish(sc->sc_mount, fss_copy_on_write, sc);
893
894 mutex_enter(&sc->sc_slock);
895 sc->sc_flags &= ~(FSS_ACTIVE|FSS_ERROR);
896 sc->sc_mount = NULL;
897 sc->sc_bdev = NODEV;
898 mutex_exit(&sc->sc_slock);
899
900 fss_softc_free(sc);
901 if (sc->sc_flags & FSS_PERSISTENT)
902 vrele(sc->sc_bs_vp);
903 else
904 vn_close(sc->sc_bs_vp, FREAD|FWRITE, l->l_cred);
905 sc->sc_bs_vp = NULL;
906 sc->sc_flags &= ~FSS_PERSISTENT;
907
908 return 0;
909 }
910
911 /*
912 * Read a cluster from the snapshotted block device to the cache.
913 */
914 static int
915 fss_read_cluster(struct fss_softc *sc, u_int32_t cl)
916 {
917 int error, todo, offset, len;
918 daddr_t dblk;
919 struct buf *bp, *mbp;
920 struct fss_cache *scp, *scl;
921
922 /*
923 * Get a free cache slot.
924 */
925 scl = sc->sc_cache+sc->sc_cache_size;
926
927 mutex_enter(&sc->sc_slock);
928
929 restart:
930 if (isset(sc->sc_copied, cl) || !FSS_ISVALID(sc)) {
931 mutex_exit(&sc->sc_slock);
932 return 0;
933 }
934
935 for (scp = sc->sc_cache; scp < scl; scp++)
936 if (scp->fc_cluster == cl) {
937 if (scp->fc_type == FSS_CACHE_VALID) {
938 mutex_exit(&sc->sc_slock);
939 return 0;
940 } else if (scp->fc_type == FSS_CACHE_BUSY) {
941 cv_wait(&scp->fc_state_cv, &sc->sc_slock);
942 goto restart;
943 }
944 }
945
946 for (scp = sc->sc_cache; scp < scl; scp++)
947 if (scp->fc_type == FSS_CACHE_FREE) {
948 scp->fc_type = FSS_CACHE_BUSY;
949 scp->fc_cluster = cl;
950 break;
951 }
952 if (scp >= scl) {
953 cv_wait(&sc->sc_cache_cv, &sc->sc_slock);
954 goto restart;
955 }
956
957 mutex_exit(&sc->sc_slock);
958
959 /*
960 * Start the read.
961 */
962 dblk = btodb(FSS_CLTOB(sc, cl));
963 if (cl == sc->sc_clcount-1) {
964 todo = sc->sc_clresid;
965 memset((char *)scp->fc_data + todo, 0, FSS_CLSIZE(sc) - todo);
966 } else
967 todo = FSS_CLSIZE(sc);
968 offset = 0;
969 mbp = getiobuf(NULL, true);
970 mbp->b_bufsize = todo;
971 mbp->b_data = scp->fc_data;
972 mbp->b_resid = mbp->b_bcount = todo;
973 mbp->b_flags = B_READ;
974 mbp->b_cflags = BC_BUSY;
975 mbp->b_dev = sc->sc_bdev;
976 while (todo > 0) {
977 len = todo;
978 if (len > MAXPHYS)
979 len = MAXPHYS;
980 if (btodb(FSS_CLTOB(sc, cl)) == dblk && len == todo)
981 bp = mbp;
982 else {
983 bp = getiobuf(NULL, true);
984 nestiobuf_setup(mbp, bp, offset, len);
985 }
986 bp->b_lblkno = 0;
987 bp->b_blkno = dblk;
988 bdev_strategy(bp);
989 dblk += btodb(len);
990 offset += len;
991 todo -= len;
992 }
993 error = biowait(mbp);
994 putiobuf(mbp);
995
996 mutex_enter(&sc->sc_slock);
997 scp->fc_type = (error ? FSS_CACHE_FREE : FSS_CACHE_VALID);
998 cv_broadcast(&scp->fc_state_cv);
999 if (error == 0) {
1000 setbit(sc->sc_copied, scp->fc_cluster);
1001 cv_signal(&sc->sc_work_cv);
1002 }
1003 mutex_exit(&sc->sc_slock);
1004
1005 return error;
1006 }
1007
1008 /*
1009 * Read/write clusters from/to backing store.
1010 * For persistent snapshots must be called with cl == 0. off is the
1011 * offset into the snapshot.
1012 */
1013 static int
1014 fss_bs_io(struct fss_softc *sc, fss_io_type rw,
1015 u_int32_t cl, off_t off, int len, void *data)
1016 {
1017 int error;
1018
1019 off += FSS_CLTOB(sc, cl);
1020
1021 vn_lock(sc->sc_bs_vp, LK_EXCLUSIVE|LK_RETRY);
1022
1023 error = vn_rdwr((rw == FSS_READ ? UIO_READ : UIO_WRITE), sc->sc_bs_vp,
1024 data, len, off, UIO_SYSSPACE,
1025 IO_ADV_ENCODE(POSIX_FADV_NOREUSE) | IO_NODELOCKED,
1026 sc->sc_bs_lwp->l_cred, NULL, NULL);
1027 if (error == 0) {
1028 mutex_enter(sc->sc_bs_vp->v_interlock);
1029 error = VOP_PUTPAGES(sc->sc_bs_vp, trunc_page(off),
1030 round_page(off+len), PGO_CLEANIT | PGO_FREE | PGO_SYNCIO);
1031 }
1032
1033 VOP_UNLOCK(sc->sc_bs_vp);
1034
1035 return error;
1036 }
1037
1038 /*
1039 * Get a pointer to the indirect slot for this cluster.
1040 */
1041 static u_int32_t *
1042 fss_bs_indir(struct fss_softc *sc, u_int32_t cl)
1043 {
1044 u_int32_t icl;
1045 int ioff;
1046
1047 icl = cl/(FSS_CLSIZE(sc)/sizeof(u_int32_t));
1048 ioff = cl%(FSS_CLSIZE(sc)/sizeof(u_int32_t));
1049
1050 if (sc->sc_indir_cur == icl)
1051 return &sc->sc_indir_data[ioff];
1052
1053 if (sc->sc_indir_dirty) {
1054 if (fss_bs_io(sc, FSS_WRITE, sc->sc_indir_cur, 0,
1055 FSS_CLSIZE(sc), (void *)sc->sc_indir_data) != 0)
1056 return NULL;
1057 setbit(sc->sc_indir_valid, sc->sc_indir_cur);
1058 }
1059
1060 sc->sc_indir_dirty = 0;
1061 sc->sc_indir_cur = icl;
1062
1063 if (isset(sc->sc_indir_valid, sc->sc_indir_cur)) {
1064 if (fss_bs_io(sc, FSS_READ, sc->sc_indir_cur, 0,
1065 FSS_CLSIZE(sc), (void *)sc->sc_indir_data) != 0)
1066 return NULL;
1067 } else
1068 memset(sc->sc_indir_data, 0, FSS_CLSIZE(sc));
1069
1070 return &sc->sc_indir_data[ioff];
1071 }
1072
1073 /*
1074 * The kernel thread (one for every active snapshot).
1075 *
1076 * After wakeup it cleans the cache and runs the I/O requests.
1077 */
1078 static void
1079 fss_bs_thread(void *arg)
1080 {
1081 bool thread_idle, is_valid;
1082 int error, i, todo, len, crotor, is_read;
1083 long off;
1084 char *addr;
1085 u_int32_t c, cl, ch, *indirp;
1086 struct buf *bp, *nbp;
1087 struct fss_softc *sc;
1088 struct fss_cache *scp, *scl;
1089
1090 sc = arg;
1091 scl = sc->sc_cache+sc->sc_cache_size;
1092 crotor = 0;
1093 thread_idle = false;
1094
1095 mutex_enter(&sc->sc_slock);
1096
1097 for (;;) {
1098 if (thread_idle)
1099 cv_wait(&sc->sc_work_cv, &sc->sc_slock);
1100 thread_idle = true;
1101 if ((sc->sc_flags & FSS_BS_THREAD) == 0) {
1102 mutex_exit(&sc->sc_slock);
1103 kthread_exit(0);
1104 }
1105
1106 /*
1107 * Process I/O requests (persistent)
1108 */
1109
1110 if (sc->sc_flags & FSS_PERSISTENT) {
1111 if ((bp = bufq_get(sc->sc_bufq)) == NULL)
1112 continue;
1113 is_valid = FSS_ISVALID(sc);
1114 is_read = (bp->b_flags & B_READ);
1115 thread_idle = false;
1116 mutex_exit(&sc->sc_slock);
1117
1118 if (is_valid) {
1119 disk_busy(sc->sc_dkdev);
1120 error = fss_bs_io(sc, FSS_READ, 0,
1121 dbtob(bp->b_blkno), bp->b_bcount,
1122 bp->b_data);
1123 disk_unbusy(sc->sc_dkdev,
1124 (error ? 0 : bp->b_bcount), is_read);
1125 } else
1126 error = ENXIO;
1127
1128 bp->b_error = error;
1129 bp->b_resid = (error ? bp->b_bcount : 0);
1130 biodone(bp);
1131
1132 mutex_enter(&sc->sc_slock);
1133 continue;
1134 }
1135
1136 /*
1137 * Clean the cache
1138 */
1139 for (i = 0; i < sc->sc_cache_size; i++) {
1140 crotor = (crotor + 1) % sc->sc_cache_size;
1141 scp = sc->sc_cache + crotor;
1142 if (scp->fc_type != FSS_CACHE_VALID)
1143 continue;
1144 mutex_exit(&sc->sc_slock);
1145
1146 thread_idle = false;
1147 indirp = fss_bs_indir(sc, scp->fc_cluster);
1148 if (indirp != NULL) {
1149 error = fss_bs_io(sc, FSS_WRITE, sc->sc_clnext,
1150 0, FSS_CLSIZE(sc), scp->fc_data);
1151 } else
1152 error = EIO;
1153
1154 mutex_enter(&sc->sc_slock);
1155 if (error == 0) {
1156 *indirp = sc->sc_clnext++;
1157 sc->sc_indir_dirty = 1;
1158 } else
1159 fss_error(sc, "write error on backing store");
1160
1161 scp->fc_type = FSS_CACHE_FREE;
1162 cv_signal(&sc->sc_cache_cv);
1163 break;
1164 }
1165
1166 /*
1167 * Process I/O requests
1168 */
1169 if ((bp = bufq_get(sc->sc_bufq)) == NULL)
1170 continue;
1171 is_valid = FSS_ISVALID(sc);
1172 is_read = (bp->b_flags & B_READ);
1173 thread_idle = false;
1174
1175 if (!is_valid) {
1176 mutex_exit(&sc->sc_slock);
1177
1178 bp->b_error = ENXIO;
1179 bp->b_resid = bp->b_bcount;
1180 biodone(bp);
1181
1182 mutex_enter(&sc->sc_slock);
1183 continue;
1184 }
1185
1186 disk_busy(sc->sc_dkdev);
1187
1188 /*
1189 * First read from the snapshotted block device unless
1190 * this request is completely covered by backing store.
1191 */
1192
1193 cl = FSS_BTOCL(sc, dbtob(bp->b_blkno));
1194 off = FSS_CLOFF(sc, dbtob(bp->b_blkno));
1195 ch = FSS_BTOCL(sc, dbtob(bp->b_blkno)+bp->b_bcount-1);
1196 error = 0;
1197 bp->b_resid = 0;
1198 bp->b_error = 0;
1199 for (c = cl; c <= ch; c++) {
1200 if (isset(sc->sc_copied, c))
1201 continue;
1202 mutex_exit(&sc->sc_slock);
1203
1204 /* Not on backing store, read from device. */
1205 nbp = getiobuf(NULL, true);
1206 nbp->b_flags = B_READ;
1207 nbp->b_resid = nbp->b_bcount = bp->b_bcount;
1208 nbp->b_bufsize = bp->b_bcount;
1209 nbp->b_data = bp->b_data;
1210 nbp->b_blkno = bp->b_blkno;
1211 nbp->b_lblkno = 0;
1212 nbp->b_dev = sc->sc_bdev;
1213 SET(nbp->b_cflags, BC_BUSY); /* mark buffer busy */
1214
1215 bdev_strategy(nbp);
1216
1217 error = biowait(nbp);
1218 if (error != 0) {
1219 bp->b_resid = bp->b_bcount;
1220 bp->b_error = nbp->b_error;
1221 disk_unbusy(sc->sc_dkdev, 0, is_read);
1222 biodone(bp);
1223 }
1224 putiobuf(nbp);
1225
1226 mutex_enter(&sc->sc_slock);
1227 break;
1228 }
1229 if (error)
1230 continue;
1231
1232 /*
1233 * Replace those parts that have been saved to backing store.
1234 */
1235
1236 addr = bp->b_data;
1237 todo = bp->b_bcount;
1238 for (c = cl; c <= ch; c++, off = 0, todo -= len, addr += len) {
1239 len = FSS_CLSIZE(sc)-off;
1240 if (len > todo)
1241 len = todo;
1242 if (isclr(sc->sc_copied, c))
1243 continue;
1244 mutex_exit(&sc->sc_slock);
1245
1246 indirp = fss_bs_indir(sc, c);
1247 if (indirp == NULL || *indirp == 0) {
1248 /*
1249 * Not on backing store. Either in cache
1250 * or hole in the snapshotted block device.
1251 */
1252
1253 mutex_enter(&sc->sc_slock);
1254 for (scp = sc->sc_cache; scp < scl; scp++)
1255 if (scp->fc_type == FSS_CACHE_VALID &&
1256 scp->fc_cluster == c)
1257 break;
1258 if (scp < scl)
1259 memcpy(addr, (char *)scp->fc_data+off,
1260 len);
1261 else
1262 memset(addr, 0, len);
1263 continue;
1264 }
1265
1266 /*
1267 * Read from backing store.
1268 */
1269 error =
1270 fss_bs_io(sc, FSS_READ, *indirp, off, len, addr);
1271
1272 mutex_enter(&sc->sc_slock);
1273 if (error) {
1274 bp->b_resid = bp->b_bcount;
1275 bp->b_error = error;
1276 break;
1277 }
1278 }
1279 mutex_exit(&sc->sc_slock);
1280
1281 disk_unbusy(sc->sc_dkdev, (error ? 0 : bp->b_bcount), is_read);
1282 biodone(bp);
1283
1284 mutex_enter(&sc->sc_slock);
1285 }
1286 }
1287
1288 #ifdef _MODULE
1289
1290 #include <sys/module.h>
1291
1292 MODULE(MODULE_CLASS_DRIVER, fss, NULL);
1293 CFDRIVER_DECL(fss, DV_DISK, NULL);
1294
1295 static int
1296 fss_modcmd(modcmd_t cmd, void *arg)
1297 {
1298 int bmajor = -1, cmajor = -1, error = 0;
1299
1300 switch (cmd) {
1301 case MODULE_CMD_INIT:
1302 mutex_init(&fss_device_lock, MUTEX_DEFAULT, IPL_NONE);
1303 error = config_cfdriver_attach(&fss_cd);
1304 if (error) {
1305 mutex_destroy(&fss_device_lock);
1306 break;
1307 }
1308 error = config_cfattach_attach(fss_cd.cd_name, &fss_ca);
1309 if (error) {
1310 config_cfdriver_detach(&fss_cd);
1311 mutex_destroy(&fss_device_lock);
1312 break;
1313 }
1314 error = devsw_attach(fss_cd.cd_name,
1315 &fss_bdevsw, &bmajor, &fss_cdevsw, &cmajor);
1316 if (error == EEXIST)
1317 error = 0;
1318 if (error) {
1319 config_cfattach_detach(fss_cd.cd_name, &fss_ca);
1320 config_cfdriver_detach(&fss_cd);
1321 mutex_destroy(&fss_device_lock);
1322 break;
1323 }
1324 break;
1325
1326 case MODULE_CMD_FINI:
1327 error = config_cfattach_detach(fss_cd.cd_name, &fss_ca);
1328 if (error)
1329 break;
1330 config_cfdriver_detach(&fss_cd);
1331 devsw_detach(&fss_bdevsw, &fss_cdevsw);
1332 mutex_destroy(&fss_device_lock);
1333 break;
1334
1335 default:
1336 error = ENOTTY;
1337 break;
1338 }
1339
1340 return error;
1341 }
1342
1343 #endif /* _MODULE */
1344