1/* $NetBSD: kern_fileassoc.c,v 1.36 2014/07/10 15:00:28 christos Exp $ */
2
3/*-
4 * Copyright (c) 2006 Elad Efrat <elad@NetBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30#include <sys/cdefs.h>
31__KERNEL_RCSID(0, "$NetBSD: kern_fileassoc.c,v 1.36 2014/07/10 15:00:28 christos Exp $");
32
33#include "opt_fileassoc.h"
34
35#include <sys/param.h>
36#include <sys/mount.h>
37#include <sys/queue.h>
38#include <sys/vnode.h>
39#include <sys/errno.h>
40#include <sys/fileassoc.h>
41#include <sys/specificdata.h>
42#include <sys/hash.h>
43#include <sys/kmem.h>
44#include <sys/once.h>
45
46#define FILEASSOC_INITIAL_TABLESIZE 128
47
48static specificdata_domain_t fileassoc_domain = NULL;
49static specificdata_key_t fileassoc_mountspecific_key;
50static ONCE_DECL(control);
51
52/*
53 * Assoc entry.
54 * Includes the assoc name for identification and private clear callback.
55 */
56struct fileassoc {
57 LIST_ENTRY(fileassoc) assoc_list;
58 const char *assoc_name; /* Name. */
59 fileassoc_cleanup_cb_t assoc_cleanup_cb; /* Clear callback. */
60 specificdata_key_t assoc_key;
61};
62
63static LIST_HEAD(, fileassoc) fileassoc_list;
64
65/* An entry in the per-mount hash table. */
66struct fileassoc_file {
67 fhandle_t *faf_handle; /* File handle */
68 specificdata_reference faf_data; /* Assoc data. */
69 u_int faf_nassocs; /* # of assocs. */
70 LIST_ENTRY(fileassoc_file) faf_list; /* List pointer. */
71};
72
73LIST_HEAD(fileassoc_hash_entry, fileassoc_file);
74
75struct fileassoc_table {
76 struct fileassoc_hash_entry *tbl_hash;
77 u_long tbl_mask; /* Hash table mask. */
78 size_t tbl_nslots; /* Number of slots. */
79 size_t tbl_nused; /* # of used slots. */
80 specificdata_reference tbl_data;
81};
82
83/*
84 * Hashing function: Takes a number modulus the mask to give back an
85 * index into the hash table.
86 */
87#define FILEASSOC_HASH(tbl, handle) \
88 (hash32_buf((handle), FHANDLE_SIZE(handle), HASH32_BUF_INIT) \
89 & ((tbl)->tbl_mask))
90
91static void *
92file_getdata(struct fileassoc_file *faf, const struct fileassoc *assoc)
93{
94
95 return specificdata_getspecific(fileassoc_domain, &faf->faf_data,
96 assoc->assoc_key);
97}
98
99static void
100file_setdata(struct fileassoc_file *faf, const struct fileassoc *assoc,
101 void *data)
102{
103
104 specificdata_setspecific(fileassoc_domain, &faf->faf_data,
105 assoc->assoc_key, data);
106}
107
108static void
109file_cleanup(struct fileassoc_file *faf, const struct fileassoc *assoc)
110{
111 fileassoc_cleanup_cb_t cb;
112 void *data;
113
114 cb = assoc->assoc_cleanup_cb;
115 if (cb == NULL) {
116 return;
117 }
118 data = file_getdata(faf, assoc);
119 (*cb)(data);
120}
121
122static void
123file_free(struct fileassoc_file *faf)
124{
125 struct fileassoc *assoc;
126
127 LIST_REMOVE(faf, faf_list);
128
129 LIST_FOREACH(assoc, &fileassoc_list, assoc_list) {
130 file_cleanup(faf, assoc);
131 }
132 vfs_composefh_free(faf->faf_handle);
133 specificdata_fini(fileassoc_domain, &faf->faf_data);
134 kmem_free(faf, sizeof(*faf));
135}
136
137static void
138table_dtor(void *v)
139{
140 struct fileassoc_table *tbl = v;
141 u_long i;
142
143 /* Remove all entries from the table and lists */
144 for (i = 0; i < tbl->tbl_nslots; i++) {
145 struct fileassoc_file *faf;
146
147 while ((faf = LIST_FIRST(&tbl->tbl_hash[i])) != NULL) {
148 file_free(faf);
149 }
150 }
151
152 /* Remove hash table and sysctl node */
153 hashdone(tbl->tbl_hash, HASH_LIST, tbl->tbl_mask);
154 specificdata_fini(fileassoc_domain, &tbl->tbl_data);
155 kmem_free(tbl, sizeof(*tbl));
156}
157
158/*
159 * Initialize the fileassoc subsystem.
160 */
161static int
162fileassoc_init(void)
163{
164 int error;
165
166 error = mount_specific_key_create(&fileassoc_mountspecific_key,
167 table_dtor);
168 if (error) {
169 return error;
170 }
171 fileassoc_domain = specificdata_domain_create();
172
173 return 0;
174}
175
176/*
177 * Register a new assoc.
178 */
179int
180fileassoc_register(const char *name, fileassoc_cleanup_cb_t cleanup_cb,
181 fileassoc_t *result)
182{
183 int error;
184 specificdata_key_t key;
185 struct fileassoc *assoc;
186
187 error = RUN_ONCE(&control, fileassoc_init);
188 if (error) {
189 return error;
190 }
191 error = specificdata_key_create(fileassoc_domain, &key, NULL);
192 if (error) {
193 return error;
194 }
195 assoc = kmem_alloc(sizeof(*assoc), KM_SLEEP);
196 assoc->assoc_name = name;
197 assoc->assoc_cleanup_cb = cleanup_cb;
198 assoc->assoc_key = key;
199
200 LIST_INSERT_HEAD(&fileassoc_list, assoc, assoc_list);
201
202 *result = assoc;
203
204 return 0;
205}
206
207/*
208 * Deregister an assoc.
209 */
210int
211fileassoc_deregister(fileassoc_t assoc)
212{
213
214 LIST_REMOVE(assoc, assoc_list);
215 specificdata_key_delete(fileassoc_domain, assoc->assoc_key);
216 kmem_free(assoc, sizeof(*assoc));
217
218 return 0;
219}
220
221/*
222 * Get the hash table for the specified device.
223 */
224static struct fileassoc_table *
225fileassoc_table_lookup(struct mount *mp)
226{
227 int error;
228
229 error = RUN_ONCE(&control, fileassoc_init);
230 if (error) {
231 return NULL;
232 }
233 return mount_getspecific(mp, fileassoc_mountspecific_key);
234}
235
236/*
237 * Perform a lookup on a hash table. If hint is non-zero then use the value
238 * of the hint as the identifier instead of performing a lookup for the
239 * fileid.
240 */
241static struct fileassoc_file *
242fileassoc_file_lookup(struct vnode *vp, fhandle_t *hint)
243{
244 struct fileassoc_table *tbl;
245 struct fileassoc_hash_entry *hash_entry;
246 struct fileassoc_file *faf;
247 size_t indx;
248 fhandle_t *th;
249 int error;
250
251 tbl = fileassoc_table_lookup(vp->v_mount);
252 if (tbl == NULL) {
253 return NULL;
254 }
255
256 if (hint == NULL) {
257 error = vfs_composefh_alloc(vp, &th);
258 if (error)
259 return (NULL);
260 } else {
261 th = hint;
262 }
263
264 indx = FILEASSOC_HASH(tbl, th);
265 hash_entry = &(tbl->tbl_hash[indx]);
266
267 LIST_FOREACH(faf, hash_entry, faf_list) {
268 if (((FHANDLE_FILEID(faf->faf_handle)->fid_len ==
269 FHANDLE_FILEID(th)->fid_len)) &&
270 (memcmp(FHANDLE_FILEID(faf->faf_handle), FHANDLE_FILEID(th),
271 (FHANDLE_FILEID(th))->fid_len) == 0)) {
272 break;
273 }
274 }
275
276 if (hint == NULL)
277 vfs_composefh_free(th);
278
279 return faf;
280}
281
282/*
283 * Return assoc data associated with a vnode.
284 */
285void *
286fileassoc_lookup(struct vnode *vp, fileassoc_t assoc)
287{
288 struct fileassoc_file *faf;
289
290 faf = fileassoc_file_lookup(vp, NULL);
291 if (faf == NULL)
292 return (NULL);
293
294 return file_getdata(faf, assoc);
295}
296
297static struct fileassoc_table *
298fileassoc_table_resize(struct fileassoc_table *tbl)
299{
300 struct fileassoc_table *newtbl;
301 u_long i;
302
303 /*
304 * Allocate a new table. Like the condition in fileassoc_file_add(),
305 * this is also temporary -- just double the number of slots.
306 */
307 newtbl = kmem_zalloc(sizeof(*newtbl), KM_SLEEP);
308 newtbl->tbl_nslots = (tbl->tbl_nslots * 2);
309 if (newtbl->tbl_nslots < tbl->tbl_nslots)
310 newtbl->tbl_nslots = tbl->tbl_nslots;
311 newtbl->tbl_hash = hashinit(newtbl->tbl_nslots, HASH_LIST,
312 true, &newtbl->tbl_mask);
313 newtbl->tbl_nused = 0;
314 specificdata_init(fileassoc_domain, &newtbl->tbl_data);
315
316 /* XXX we need to make sure nothing uses fileassoc here! */
317
318 for (i = 0; i < tbl->tbl_nslots; i++) {
319 struct fileassoc_file *faf;
320
321 while ((faf = LIST_FIRST(&tbl->tbl_hash[i])) != NULL) {
322 struct fileassoc_hash_entry *hash_entry;
323 size_t indx;
324
325 LIST_REMOVE(faf, faf_list);
326
327 indx = FILEASSOC_HASH(newtbl, faf->faf_handle);
328 hash_entry = &(newtbl->tbl_hash[indx]);
329
330 LIST_INSERT_HEAD(hash_entry, faf, faf_list);
331
332 newtbl->tbl_nused++;
333 }
334 }
335
336 if (tbl->tbl_nused != newtbl->tbl_nused)
337 panic("fileassoc_table_resize: inconsistency detected! "
338 "needed %zu entries, got %zu", tbl->tbl_nused,
339 newtbl->tbl_nused);
340
341 hashdone(tbl->tbl_hash, HASH_LIST, tbl->tbl_mask);
342 specificdata_fini(fileassoc_domain, &tbl->tbl_data);
343 kmem_free(tbl, sizeof(*tbl));
344
345 return (newtbl);
346}
347
348/*
349 * Create a new fileassoc table.
350 */
351static struct fileassoc_table *
352fileassoc_table_add(struct mount *mp)
353{
354 struct fileassoc_table *tbl;
355
356 /* Check for existing table for device. */
357 tbl = fileassoc_table_lookup(mp);
358 if (tbl != NULL)
359 return (tbl);
360
361 /* Allocate and initialize a table. */
362 tbl = kmem_zalloc(sizeof(*tbl), KM_SLEEP);
363 tbl->tbl_nslots = FILEASSOC_INITIAL_TABLESIZE;
364 tbl->tbl_hash = hashinit(tbl->tbl_nslots, HASH_LIST, true,
365 &tbl->tbl_mask);
366 tbl->tbl_nused = 0;
367 specificdata_init(fileassoc_domain, &tbl->tbl_data);
368
369 mount_setspecific(mp, fileassoc_mountspecific_key, tbl);
370
371 return (tbl);
372}
373
374/*
375 * Delete a table.
376 */
377int
378fileassoc_table_delete(struct mount *mp)
379{
380 struct fileassoc_table *tbl;
381
382 tbl = fileassoc_table_lookup(mp);
383 if (tbl == NULL)
384 return (EEXIST);
385
386 mount_setspecific(mp, fileassoc_mountspecific_key, NULL);
387 table_dtor(tbl);
388
389 return (0);
390}
391
392/*
393 * Run a callback for each assoc in a table.
394 */
395int
396fileassoc_table_run(struct mount *mp, fileassoc_t assoc, fileassoc_cb_t cb,
397 void *cookie)
398{
399 struct fileassoc_table *tbl;
400 u_long i;
401
402 tbl = fileassoc_table_lookup(mp);
403 if (tbl == NULL)
404 return (EEXIST);
405
406 for (i = 0; i < tbl->tbl_nslots; i++) {
407 struct fileassoc_file *faf;
408
409 LIST_FOREACH(faf, &tbl->tbl_hash[i], faf_list) {
410 void *data;
411
412 data = file_getdata(faf, assoc);
413 if (data != NULL)
414 cb(data, cookie);
415 }
416 }
417
418 return (0);
419}
420
421/*
422 * Clear a table for a given assoc.
423 */
424int
425fileassoc_table_clear(struct mount *mp, fileassoc_t assoc)
426{
427 struct fileassoc_table *tbl;
428 u_long i;
429
430 tbl = fileassoc_table_lookup(mp);
431 if (tbl == NULL)
432 return (EEXIST);
433
434 for (i = 0; i < tbl->tbl_nslots; i++) {
435 struct fileassoc_file *faf;
436
437 LIST_FOREACH(faf, &tbl->tbl_hash[i], faf_list) {
438 file_cleanup(faf, assoc);
439 file_setdata(faf, assoc, NULL);
440 }
441 }
442
443 return (0);
444}
445
446/*
447 * Add a file entry to a table.
448 */
449static struct fileassoc_file *
450fileassoc_file_add(struct vnode *vp, fhandle_t *hint)
451{
452 struct fileassoc_table *tbl;
453 struct fileassoc_hash_entry *hash_entry;
454 struct fileassoc_file *faf;
455 size_t indx;
456 fhandle_t *th;
457 int error;
458
459 if (hint == NULL) {
460 error = vfs_composefh_alloc(vp, &th);
461 if (error)
462 return (NULL);
463 } else
464 th = hint;
465
466 faf = fileassoc_file_lookup(vp, th);
467 if (faf != NULL) {
468 if (hint == NULL)
469 vfs_composefh_free(th);
470
471 return (faf);
472 }
473
474 tbl = fileassoc_table_lookup(vp->v_mount);
475 if (tbl == NULL) {
476 tbl = fileassoc_table_add(vp->v_mount);
477 }
478
479 indx = FILEASSOC_HASH(tbl, th);
480 hash_entry = &(tbl->tbl_hash[indx]);
481
482 faf = kmem_zalloc(sizeof(*faf), KM_SLEEP);
483 faf->faf_handle = th;
484 specificdata_init(fileassoc_domain, &faf->faf_data);
485 LIST_INSERT_HEAD(hash_entry, faf, faf_list);
486
487 /*
488 * This decides when we need to resize the table. For now,
489 * resize it whenever we "filled" up the number of slots it
490 * has. That's not really true unless of course we had zero
491 * collisions. Think positive! :)
492 */
493 if (++(tbl->tbl_nused) == tbl->tbl_nslots) {
494 struct fileassoc_table *newtbl;
495
496 newtbl = fileassoc_table_resize(tbl);
497 mount_setspecific(vp->v_mount, fileassoc_mountspecific_key,
498 newtbl);
499 }
500
501 return (faf);
502}
503
504/*
505 * Delete a file entry from a table.
506 */
507int
508fileassoc_file_delete(struct vnode *vp)
509{
510 struct fileassoc_table *tbl;
511 struct fileassoc_file *faf;
512
513 /* Pre-check if fileassoc is used. XXX */
514 if (!fileassoc_domain) {
515 return ENOENT;
516 }
517 KERNEL_LOCK(1, NULL);
518
519 faf = fileassoc_file_lookup(vp, NULL);
520 if (faf == NULL) {
521 KERNEL_UNLOCK_ONE(NULL);
522 return (ENOENT);
523 }
524
525 file_free(faf);
526
527 tbl = fileassoc_table_lookup(vp->v_mount);
528 KASSERT(tbl != NULL);
529 --(tbl->tbl_nused); /* XXX gc? */
530
531 KERNEL_UNLOCK_ONE(NULL);
532
533 return (0);
534}
535
536/*
537 * Add an assoc to a vnode.
538 */
539int
540fileassoc_add(struct vnode *vp, fileassoc_t assoc, void *data)
541{
542 struct fileassoc_file *faf;
543 void *olddata;
544
545 faf = fileassoc_file_lookup(vp, NULL);
546 if (faf == NULL) {
547 faf = fileassoc_file_add(vp, NULL);
548 if (faf == NULL)
549 return (ENOTDIR);
550 }
551
552 olddata = file_getdata(faf, assoc);
553 if (olddata != NULL)
554 return (EEXIST);
555
556 file_setdata(faf, assoc, data);
557
558 faf->faf_nassocs++;
559
560 return (0);
561}
562
563/*
564 * Clear an assoc from a vnode.
565 */
566int
567fileassoc_clear(struct vnode *vp, fileassoc_t assoc)
568{
569 struct fileassoc_file *faf;
570
571 faf = fileassoc_file_lookup(vp, NULL);
572 if (faf == NULL)
573 return (ENOENT);
574
575 file_cleanup(faf, assoc);
576 file_setdata(faf, assoc, NULL);
577
578 --(faf->faf_nassocs); /* XXX gc? */
579
580 return (0);
581}
582