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Patrick Welche <prlw1@cam.ac.uk>
[netbsd-mini2440.git] / external / cddl / osnet / dist / uts / common / fs / zfs / dbuf.c
blob11187b071db62de3b34d4e481f57539846d240a9
1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
23 * Use is subject to license terms.
24 */
25
26 #include <sys/zfs_context.h>
27 #include <sys/dmu.h>
28 #include <sys/dmu_impl.h>
29 #include <sys/dbuf.h>
30 #include <sys/dmu_objset.h>
31 #include <sys/dsl_dataset.h>
32 #include <sys/dsl_dir.h>
33 #include <sys/dmu_tx.h>
34 #include <sys/spa.h>
35 #include <sys/zio.h>
36 #include <sys/dmu_zfetch.h>
37
38 static void dbuf_destroy(dmu_buf_impl_t *db);
39 static int dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
40 static void dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx);
41 static arc_done_func_t dbuf_write_ready;
42 static arc_done_func_t dbuf_write_done;
43 static zio_done_func_t dbuf_skip_write_ready;
44 static zio_done_func_t dbuf_skip_write_done;
45
46 /*
47 * Global data structures and functions for the dbuf cache.
48 */
49 static kmem_cache_t *dbuf_cache;
50
51 /* ARGSUSED */
52 static int
53 dbuf_cons(void *vdb, void *unused, int kmflag)
54 {
55 dmu_buf_impl_t *db = unused;
56 bzero(db, sizeof (dmu_buf_impl_t));
57
58 mutex_init(&db->db_mtx, NULL, MUTEX_DEFAULT, NULL);
59 cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL);
60 refcount_create(&db->db_holds);
61 return (0);
62 }
63
64 /* ARGSUSED */
65 static void
66 dbuf_dest(void *vdb, void *unused)
67 {
68 dmu_buf_impl_t *db = unused;
69 mutex_destroy(&db->db_mtx);
70 cv_destroy(&db->db_changed);
71 refcount_destroy(&db->db_holds);
72 }
73
74 /*
75 * dbuf hash table routines
76 */
77 static dbuf_hash_table_t dbuf_hash_table;
78
79 static uint64_t dbuf_hash_count;
80
81 static uint64_t
82 dbuf_hash(void *os, uint64_t obj, uint8_t lvl, uint64_t blkid)
83 {
84 uintptr_t osv = (uintptr_t)os;
85 uint64_t crc = -1ULL;
86
87 ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY);
88 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (lvl)) & 0xFF];
89 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (osv >> 6)) & 0xFF];
90 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 0)) & 0xFF];
91 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 8)) & 0xFF];
92 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 0)) & 0xFF];
93 crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 8)) & 0xFF];
94
95 crc ^= (osv>>14) ^ (obj>>16) ^ (blkid>>16);
96
97 return (crc);
98 }
99
100 #define DBUF_HASH(os, obj, level, blkid) dbuf_hash(os, obj, level, blkid);
101
102 #define DBUF_EQUAL(dbuf, os, obj, level, blkid) \
103 ((dbuf)->db.db_object == (obj) && \
104 (dbuf)->db_objset == (os) && \
105 (dbuf)->db_level == (level) && \
106 (dbuf)->db_blkid == (blkid))
107
108 dmu_buf_impl_t *
109 dbuf_find(dnode_t *dn, uint8_t level, uint64_t blkid)
110 {
111 dbuf_hash_table_t *h = &dbuf_hash_table;
112 objset_impl_t *os = dn->dn_objset;
113 uint64_t obj = dn->dn_object;
114 uint64_t hv = DBUF_HASH(os, obj, level, blkid);
115 uint64_t idx = hv & h->hash_table_mask;
116 dmu_buf_impl_t *db;
117
118 mutex_enter(DBUF_HASH_MUTEX(h, idx));
119 for (db = h->hash_table[idx]; db != NULL; db = db->db_hash_next) {
120 if (DBUF_EQUAL(db, os, obj, level, blkid)) {
121 mutex_enter(&db->db_mtx);
122 if (db->db_state != DB_EVICTING) {
123 mutex_exit(DBUF_HASH_MUTEX(h, idx));
124 return (db);
125 }
126 mutex_exit(&db->db_mtx);
127 }
128 }
129 mutex_exit(DBUF_HASH_MUTEX(h, idx));
130 return (NULL);
131 }
132
133 /*
134 * Insert an entry into the hash table. If there is already an element
135 * equal to elem in the hash table, then the already existing element
136 * will be returned and the new element will not be inserted.
137 * Otherwise returns NULL.
138 */
139 static dmu_buf_impl_t *
140 dbuf_hash_insert(dmu_buf_impl_t *db)
141 {
142 dbuf_hash_table_t *h = &dbuf_hash_table;
143 objset_impl_t *os = db->db_objset;
144 uint64_t obj = db->db.db_object;
145 int level = db->db_level;
146 uint64_t blkid = db->db_blkid;
147 uint64_t hv = DBUF_HASH(os, obj, level, blkid);
148 uint64_t idx = hv & h->hash_table_mask;
149 dmu_buf_impl_t *dbf;
150
151 mutex_enter(DBUF_HASH_MUTEX(h, idx));
152 for (dbf = h->hash_table[idx]; dbf != NULL; dbf = dbf->db_hash_next) {
153 if (DBUF_EQUAL(dbf, os, obj, level, blkid)) {
154 mutex_enter(&dbf->db_mtx);
155 if (dbf->db_state != DB_EVICTING) {
156 mutex_exit(DBUF_HASH_MUTEX(h, idx));
157 return (dbf);
158 }
159 mutex_exit(&dbf->db_mtx);
160 }
161 }
162
163 mutex_enter(&db->db_mtx);
164 db->db_hash_next = h->hash_table[idx];
165 h->hash_table[idx] = db;
166 mutex_exit(DBUF_HASH_MUTEX(h, idx));
167 atomic_add_64(&dbuf_hash_count, 1);
168
169 return (NULL);
170 }
171
172 /*
173 * Remove an entry from the hash table. This operation will
174 * fail if there are any existing holds on the db.
175 */
176 static void
177 dbuf_hash_remove(dmu_buf_impl_t *db)
178 {
179 dbuf_hash_table_t *h = &dbuf_hash_table;
180 uint64_t hv = DBUF_HASH(db->db_objset, db->db.db_object,
181 db->db_level, db->db_blkid);
182 uint64_t idx = hv & h->hash_table_mask;
183 dmu_buf_impl_t *dbf, **dbp;
184
185 /*
186 * We musn't hold db_mtx to maintin lock ordering:
187 * DBUF_HASH_MUTEX > db_mtx.
188 */
189 ASSERT(refcount_is_zero(&db->db_holds));
190 ASSERT(db->db_state == DB_EVICTING);
191 ASSERT(!MUTEX_HELD(&db->db_mtx));
192
193 mutex_enter(DBUF_HASH_MUTEX(h, idx));
194 dbp = &h->hash_table[idx];
195 while ((dbf = *dbp) != db) {
196 dbp = &dbf->db_hash_next;
197 ASSERT(dbf != NULL);
198 }
199 *dbp = db->db_hash_next;
200 db->db_hash_next = NULL;
201 mutex_exit(DBUF_HASH_MUTEX(h, idx));
202 atomic_add_64(&dbuf_hash_count, -1);
203 }
204
205 static arc_evict_func_t dbuf_do_evict;
206
207 static void
208 dbuf_evict_user(dmu_buf_impl_t *db)
209 {
210 ASSERT(MUTEX_HELD(&db->db_mtx));
211
212 if (db->db_level != 0 || db->db_evict_func == NULL)
213 return;
214
215 if (db->db_user_data_ptr_ptr)
216 *db->db_user_data_ptr_ptr = db->db.db_data;
217 db->db_evict_func(&db->db, db->db_user_ptr);
218 db->db_user_ptr = NULL;
219 db->db_user_data_ptr_ptr = NULL;
220 db->db_evict_func = NULL;
221 }
222
223 void
224 dbuf_evict(dmu_buf_impl_t *db)
225 {
226 ASSERT(MUTEX_HELD(&db->db_mtx));
227 ASSERT(db->db_buf == NULL);
228 ASSERT(db->db_data_pending == NULL);
229
230 dbuf_clear(db);
231 dbuf_destroy(db);
232 }
233
234 void
235 dbuf_init(void)
236 {
237 uint64_t hsize = 1ULL << 16;
238 dbuf_hash_table_t *h = &dbuf_hash_table;
239 int i;
240
241 /*
242 * The hash table is big enough to fill all of physical memory
243 * with an average 4K block size. The table will take up
244 * totalmem*sizeof(void*)/4K (i.e. 2MB/GB with 8-byte pointers).
245 */
246 while (hsize * 4096 < (uint64_t)physmem * PAGESIZE)
247 hsize <<= 1;
248
249 retry:
250 h->hash_table_mask = hsize - 1;
251 h->hash_table = kmem_zalloc(hsize * sizeof (void *), KM_NOSLEEP);
252 if (h->hash_table == NULL) {
253 /* XXX - we should really return an error instead of assert */
254 ASSERT(hsize > (1ULL << 10));
255 hsize >>= 1;
256 goto retry;
257 }
258
259 dbuf_cache = kmem_cache_create("dmu_buf_impl_t",
260 sizeof (dmu_buf_impl_t),
261 0, dbuf_cons, dbuf_dest, NULL, NULL, NULL, 0);
262
263 for (i = 0; i < DBUF_MUTEXES; i++)
264 mutex_init(&h->hash_mutexes[i], NULL, MUTEX_DEFAULT, NULL);
265 }
266
267 void
268 dbuf_fini(void)
269 {
270 dbuf_hash_table_t *h = &dbuf_hash_table;
271 int i;
272
273 for (i = 0; i < DBUF_MUTEXES; i++)
274 mutex_destroy(&h->hash_mutexes[i]);
275 kmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *));
276 kmem_cache_destroy(dbuf_cache);
277 }
278
279 /*
280 * Other stuff.
281 */
282
283 #ifdef ZFS_DEBUG
284 static void
285 dbuf_verify(dmu_buf_impl_t *db)
286 {
287 dnode_t *dn = db->db_dnode;
288
289 ASSERT(MUTEX_HELD(&db->db_mtx));
290
291 if (!(zfs_flags & ZFS_DEBUG_DBUF_VERIFY))
292 return;
293
294 ASSERT(db->db_objset != NULL);
295 if (dn == NULL) {
296 ASSERT(db->db_parent == NULL);
297 ASSERT(db->db_blkptr == NULL);
298 } else {
299 ASSERT3U(db->db.db_object, ==, dn->dn_object);
300 ASSERT3P(db->db_objset, ==, dn->dn_objset);
301 ASSERT3U(db->db_level, <, dn->dn_nlevels);
302 ASSERT(db->db_blkid == DB_BONUS_BLKID ||
303 list_head(&dn->dn_dbufs));
304 }
305 if (db->db_blkid == DB_BONUS_BLKID) {
306 ASSERT(dn != NULL);
307 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
308 ASSERT3U(db->db.db_offset, ==, DB_BONUS_BLKID);
309 } else {
310 ASSERT3U(db->db.db_offset, ==, db->db_blkid * db->db.db_size);
311 }
312
313 /*
314 * We can't assert that db_size matches dn_datablksz because it
315 * can be momentarily different when another thread is doing
316 * dnode_set_blksz().
317 */
318 if (db->db_level == 0 && db->db.db_object == DMU_META_DNODE_OBJECT) {
319 dbuf_dirty_record_t *dr = db->db_data_pending;
320 /*
321 * It should only be modified in syncing context, so
322 * make sure we only have one copy of the data.
323 */
324 ASSERT(dr == NULL || dr->dt.dl.dr_data == db->db_buf);
325 }
326
327 /* verify db->db_blkptr */
328 if (db->db_blkptr) {
329 if (db->db_parent == dn->dn_dbuf) {
330 /* db is pointed to by the dnode */
331 /* ASSERT3U(db->db_blkid, <, dn->dn_nblkptr); */
332 if (db->db.db_object == DMU_META_DNODE_OBJECT)
333 ASSERT(db->db_parent == NULL);
334 else
335 ASSERT(db->db_parent != NULL);
336 ASSERT3P(db->db_blkptr, ==,
337 &dn->dn_phys->dn_blkptr[db->db_blkid]);
338 } else {
339 /* db is pointed to by an indirect block */
340 int epb = db->db_parent->db.db_size >> SPA_BLKPTRSHIFT;
341 ASSERT3U(db->db_parent->db_level, ==, db->db_level+1);
342 ASSERT3U(db->db_parent->db.db_object, ==,
343 db->db.db_object);
344 /*
345 * dnode_grow_indblksz() can make this fail if we don't
346 * have the struct_rwlock. XXX indblksz no longer
347 * grows. safe to do this now?
348 */
349 if (RW_WRITE_HELD(&db->db_dnode->dn_struct_rwlock)) {
350 ASSERT3P(db->db_blkptr, ==,
351 ((blkptr_t *)db->db_parent->db.db_data +
352 db->db_blkid % epb));
353 }
354 }
355 }
356 if ((db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr)) &&
357 db->db.db_data && db->db_blkid != DB_BONUS_BLKID &&
358 db->db_state != DB_FILL && !dn->dn_free_txg) {
359 /*
360 * If the blkptr isn't set but they have nonzero data,
361 * it had better be dirty, otherwise we'll lose that
362 * data when we evict this buffer.
363 */
364 if (db->db_dirtycnt == 0) {
365 uint64_t *buf = db->db.db_data;
366 int i;
367
368 for (i = 0; i < db->db.db_size >> 3; i++) {
369 ASSERT(buf[i] == 0);
370 }
371 }
372 }
373 }
374 #endif
375
376 static void
377 dbuf_update_data(dmu_buf_impl_t *db)
378 {
379 ASSERT(MUTEX_HELD(&db->db_mtx));
380 if (db->db_level == 0 && db->db_user_data_ptr_ptr) {
381 ASSERT(!refcount_is_zero(&db->db_holds));
382 *db->db_user_data_ptr_ptr = db->db.db_data;
383 }
384 }
385
386 static void
387 dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf)
388 {
389 ASSERT(MUTEX_HELD(&db->db_mtx));
390 ASSERT(db->db_buf == NULL || !arc_has_callback(db->db_buf));
391 db->db_buf = buf;
392 if (buf != NULL) {
393 ASSERT(buf->b_data != NULL);
394 db->db.db_data = buf->b_data;
395 if (!arc_released(buf))
396 arc_set_callback(buf, dbuf_do_evict, db);
397 dbuf_update_data(db);
398 } else {
399 dbuf_evict_user(db);
400 db->db.db_data = NULL;
401 if (db->db_state != DB_NOFILL)
402 db->db_state = DB_UNCACHED;
403 }
404 }
405
406 uint64_t
407 dbuf_whichblock(dnode_t *dn, uint64_t offset)
408 {
409 if (dn->dn_datablkshift) {
410 return (offset >> dn->dn_datablkshift);
411 } else {
412 ASSERT3U(offset, <, dn->dn_datablksz);
413 return (0);
414 }
415 }
416
417 static void
418 dbuf_read_done(zio_t *zio, arc_buf_t *buf, void *vdb)
419 {
420 dmu_buf_impl_t *db = vdb;
421
422 mutex_enter(&db->db_mtx);
423 ASSERT3U(db->db_state, ==, DB_READ);
424 /*
425 * All reads are synchronous, so we must have a hold on the dbuf
426 */
427 ASSERT(refcount_count(&db->db_holds) > 0);
428 ASSERT(db->db_buf == NULL);
429 ASSERT(db->db.db_data == NULL);
430 if (db->db_level == 0 && db->db_freed_in_flight) {
431 /* we were freed in flight; disregard any error */
432 arc_release(buf, db);
433 bzero(buf->b_data, db->db.db_size);
434 arc_buf_freeze(buf);
435 db->db_freed_in_flight = FALSE;
436 dbuf_set_data(db, buf);
437 db->db_state = DB_CACHED;
438 } else if (zio == NULL || zio->io_error == 0) {
439 dbuf_set_data(db, buf);
440 db->db_state = DB_CACHED;
441 } else {
442 ASSERT(db->db_blkid != DB_BONUS_BLKID);
443 ASSERT3P(db->db_buf, ==, NULL);
444 VERIFY(arc_buf_remove_ref(buf, db) == 1);
445 db->db_state = DB_UNCACHED;
446 }
447 cv_broadcast(&db->db_changed);
448 mutex_exit(&db->db_mtx);
449 dbuf_rele(db, NULL);
450 }
451
452 static void
453 dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t *flags)
454 {
455 dnode_t *dn = db->db_dnode;
456 zbookmark_t zb;
457 uint32_t aflags = ARC_NOWAIT;
458 arc_buf_t *pbuf;
459
460 ASSERT(!refcount_is_zero(&db->db_holds));
461 /* We need the struct_rwlock to prevent db_blkptr from changing. */
462 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
463 ASSERT(MUTEX_HELD(&db->db_mtx));
464 ASSERT(db->db_state == DB_UNCACHED);
465 ASSERT(db->db_buf == NULL);
466
467 if (db->db_blkid == DB_BONUS_BLKID) {
468 int bonuslen = dn->dn_bonuslen;
469
470 ASSERT3U(bonuslen, <=, db->db.db_size);
471 db->db.db_data = zio_buf_alloc(DN_MAX_BONUSLEN);
472 arc_space_consume(DN_MAX_BONUSLEN);
473 if (bonuslen < DN_MAX_BONUSLEN)
474 bzero(db->db.db_data, DN_MAX_BONUSLEN);
475 bcopy(DN_BONUS(dn->dn_phys), db->db.db_data,
476 bonuslen);
477 dbuf_update_data(db);
478 db->db_state = DB_CACHED;
479 mutex_exit(&db->db_mtx);
480 return;
481 }
482
483 /*
484 * Recheck BP_IS_HOLE() after dnode_block_freed() in case dnode_sync()
485 * processes the delete record and clears the bp while we are waiting
486 * for the dn_mtx (resulting in a "no" from block_freed).
487 */
488 if (db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr) ||
489 (db->db_level == 0 && (dnode_block_freed(dn, db->db_blkid) ||
490 BP_IS_HOLE(db->db_blkptr)))) {
491 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
492
493 dbuf_set_data(db, arc_buf_alloc(dn->dn_objset->os_spa,
494 db->db.db_size, db, type));
495 bzero(db->db.db_data, db->db.db_size);
496 db->db_state = DB_CACHED;
497 *flags |= DB_RF_CACHED;
498 mutex_exit(&db->db_mtx);
499 return;
500 }
501
502 db->db_state = DB_READ;
503 mutex_exit(&db->db_mtx);
504
505 if (DBUF_IS_L2CACHEABLE(db))
506 aflags |= ARC_L2CACHE;
507
508 zb.zb_objset = db->db_objset->os_dsl_dataset ?
509 db->db_objset->os_dsl_dataset->ds_object : 0;
510 zb.zb_object = db->db.db_object;
511 zb.zb_level = db->db_level;
512 zb.zb_blkid = db->db_blkid;
513
514 dbuf_add_ref(db, NULL);
515 /* ZIO_FLAG_CANFAIL callers have to check the parent zio's error */
516
517 if (db->db_parent)
518 pbuf = db->db_parent->db_buf;
519 else
520 pbuf = db->db_objset->os_phys_buf;
521
522 (void) arc_read(zio, dn->dn_objset->os_spa, db->db_blkptr, pbuf,
523 dbuf_read_done, db, ZIO_PRIORITY_SYNC_READ,
524 (*flags & DB_RF_CANFAIL) ? ZIO_FLAG_CANFAIL : ZIO_FLAG_MUSTSUCCEED,
525 &aflags, &zb);
526 if (aflags & ARC_CACHED)
527 *flags |= DB_RF_CACHED;
528 }
529
530 int
531 dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
532 {
533 int err = 0;
534 int havepzio = (zio != NULL);
535 int prefetch;
536
537 /*
538 * We don't have to hold the mutex to check db_state because it
539 * can't be freed while we have a hold on the buffer.
540 */
541 ASSERT(!refcount_is_zero(&db->db_holds));
542
543 if (db->db_state == DB_NOFILL)
544 return (EIO);
545
546 if ((flags & DB_RF_HAVESTRUCT) == 0)
547 rw_enter(&db->db_dnode->dn_struct_rwlock, RW_READER);
548
549 prefetch = db->db_level == 0 && db->db_blkid != DB_BONUS_BLKID &&
550 (flags & DB_RF_NOPREFETCH) == 0 && db->db_dnode != NULL &&
551 DBUF_IS_CACHEABLE(db);
552
553 mutex_enter(&db->db_mtx);
554 if (db->db_state == DB_CACHED) {
555 mutex_exit(&db->db_mtx);
556 if (prefetch)
557 dmu_zfetch(&db->db_dnode->dn_zfetch, db->db.db_offset,
558 db->db.db_size, TRUE);
559 if ((flags & DB_RF_HAVESTRUCT) == 0)
560 rw_exit(&db->db_dnode->dn_struct_rwlock);
561 } else if (db->db_state == DB_UNCACHED) {
562 if (zio == NULL) {
563 zio = zio_root(db->db_dnode->dn_objset->os_spa,
564 NULL, NULL, ZIO_FLAG_CANFAIL);
565 }
566 dbuf_read_impl(db, zio, &flags);
567
568 /* dbuf_read_impl has dropped db_mtx for us */
569
570 if (prefetch)
571 dmu_zfetch(&db->db_dnode->dn_zfetch, db->db.db_offset,
572 db->db.db_size, flags & DB_RF_CACHED);
573
574 if ((flags & DB_RF_HAVESTRUCT) == 0)
575 rw_exit(&db->db_dnode->dn_struct_rwlock);
576
577 if (!havepzio)
578 err = zio_wait(zio);
579 } else {
580 mutex_exit(&db->db_mtx);
581 if (prefetch)
582 dmu_zfetch(&db->db_dnode->dn_zfetch, db->db.db_offset,
583 db->db.db_size, TRUE);
584 if ((flags & DB_RF_HAVESTRUCT) == 0)
585 rw_exit(&db->db_dnode->dn_struct_rwlock);
586
587 mutex_enter(&db->db_mtx);
588 if ((flags & DB_RF_NEVERWAIT) == 0) {
589 while (db->db_state == DB_READ ||
590 db->db_state == DB_FILL) {
591 ASSERT(db->db_state == DB_READ ||
592 (flags & DB_RF_HAVESTRUCT) == 0);
593 cv_wait(&db->db_changed, &db->db_mtx);
594 }
595 if (db->db_state == DB_UNCACHED)
596 err = EIO;
597 }
598 mutex_exit(&db->db_mtx);
599 }
600
601 ASSERT(err || havepzio || db->db_state == DB_CACHED);
602 return (err);
603 }
604
605 static void
606 dbuf_noread(dmu_buf_impl_t *db)
607 {
608 ASSERT(!refcount_is_zero(&db->db_holds));
609 ASSERT(db->db_blkid != DB_BONUS_BLKID);
610 mutex_enter(&db->db_mtx);
611 while (db->db_state == DB_READ || db->db_state == DB_FILL)
612 cv_wait(&db->db_changed, &db->db_mtx);
613 if (db->db_state == DB_UNCACHED) {
614 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
615
616 ASSERT(db->db_buf == NULL);
617 ASSERT(db->db.db_data == NULL);
618 dbuf_set_data(db, arc_buf_alloc(db->db_dnode->dn_objset->os_spa,
619 db->db.db_size, db, type));
620 db->db_state = DB_FILL;
621 } else if (db->db_state == DB_NOFILL) {
622 dbuf_set_data(db, NULL);
623 } else {
624 ASSERT3U(db->db_state, ==, DB_CACHED);
625 }
626 mutex_exit(&db->db_mtx);
627 }
628
629 /*
630 * This is our just-in-time copy function. It makes a copy of
631 * buffers, that have been modified in a previous transaction
632 * group, before we modify them in the current active group.
633 *
634 * This function is used in two places: when we are dirtying a
635 * buffer for the first time in a txg, and when we are freeing
636 * a range in a dnode that includes this buffer.
637 *
638 * Note that when we are called from dbuf_free_range() we do
639 * not put a hold on the buffer, we just traverse the active
640 * dbuf list for the dnode.
641 */
642 static void
643 dbuf_fix_old_data(dmu_buf_impl_t *db, uint64_t txg)
644 {
645 dbuf_dirty_record_t *dr = db->db_last_dirty;
646
647 ASSERT(MUTEX_HELD(&db->db_mtx));
648 ASSERT(db->db.db_data != NULL);
649 ASSERT(db->db_level == 0);
650 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT);
651
652 if (dr == NULL ||
653 (dr->dt.dl.dr_data !=
654 ((db->db_blkid == DB_BONUS_BLKID) ? db->db.db_data : db->db_buf)))
655 return;
656
657 /*
658 * If the last dirty record for this dbuf has not yet synced
659 * and its referencing the dbuf data, either:
660 * reset the reference to point to a new copy,
661 * or (if there a no active holders)
662 * just null out the current db_data pointer.
663 */
664 ASSERT(dr->dr_txg >= txg - 2);
665 if (db->db_blkid == DB_BONUS_BLKID) {
666 /* Note that the data bufs here are zio_bufs */
667 dr->dt.dl.dr_data = zio_buf_alloc(DN_MAX_BONUSLEN);
668 arc_space_consume(DN_MAX_BONUSLEN);
669 bcopy(db->db.db_data, dr->dt.dl.dr_data, DN_MAX_BONUSLEN);
670 } else if (refcount_count(&db->db_holds) > db->db_dirtycnt) {
671 int size = db->db.db_size;
672 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
673 dr->dt.dl.dr_data = arc_buf_alloc(
674 db->db_dnode->dn_objset->os_spa, size, db, type);
675 bcopy(db->db.db_data, dr->dt.dl.dr_data->b_data, size);
676 } else {
677 dbuf_set_data(db, NULL);
678 }
679 }
680
681 void
682 dbuf_unoverride(dbuf_dirty_record_t *dr)
683 {
684 dmu_buf_impl_t *db = dr->dr_dbuf;
685 uint64_t txg = dr->dr_txg;
686
687 ASSERT(MUTEX_HELD(&db->db_mtx));
688 ASSERT(dr->dt.dl.dr_override_state != DR_IN_DMU_SYNC);
689 ASSERT(db->db_level == 0);
690
691 if (db->db_blkid == DB_BONUS_BLKID ||
692 dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN)
693 return;
694
695 /* free this block */
696 if (!BP_IS_HOLE(&dr->dt.dl.dr_overridden_by)) {
697 /* XXX can get silent EIO here */
698 (void) dsl_free(NULL,
699 spa_get_dsl(db->db_dnode->dn_objset->os_spa),
700 txg, &dr->dt.dl.dr_overridden_by, NULL, NULL, ARC_WAIT);
701 }
702 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
703 /*
704 * Release the already-written buffer, so we leave it in
705 * a consistent dirty state. Note that all callers are
706 * modifying the buffer, so they will immediately do
707 * another (redundant) arc_release(). Therefore, leave
708 * the buf thawed to save the effort of freezing &
709 * immediately re-thawing it.
710 */
711 arc_release(dr->dt.dl.dr_data, db);
712 }
713
714 /*
715 * Evict (if its unreferenced) or clear (if its referenced) any level-0
716 * data blocks in the free range, so that any future readers will find
717 * empty blocks. Also, if we happen accross any level-1 dbufs in the
718 * range that have not already been marked dirty, mark them dirty so
719 * they stay in memory.
720 */
721 void
722 dbuf_free_range(dnode_t *dn, uint64_t start, uint64_t end, dmu_tx_t *tx)
723 {
724 dmu_buf_impl_t *db, *db_next;
725 uint64_t txg = tx->tx_txg;
726 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
727 uint64_t first_l1 = start >> epbs;
728 uint64_t last_l1 = end >> epbs;
729
730 if (end > dn->dn_maxblkid) {
731 end = dn->dn_maxblkid;
732 last_l1 = end >> epbs;
733 }
734 dprintf_dnode(dn, "start=%llu end=%llu\n", start, end);
735 mutex_enter(&dn->dn_dbufs_mtx);
736 for (db = list_head(&dn->dn_dbufs); db; db = db_next) {
737 db_next = list_next(&dn->dn_dbufs, db);
738 ASSERT(db->db_blkid != DB_BONUS_BLKID);
739
740 if (db->db_level == 1 &&
741 db->db_blkid >= first_l1 && db->db_blkid <= last_l1) {
742 mutex_enter(&db->db_mtx);
743 if (db->db_last_dirty &&
744 db->db_last_dirty->dr_txg < txg) {
745 dbuf_add_ref(db, FTAG);
746 mutex_exit(&db->db_mtx);
747 dbuf_will_dirty(db, tx);
748 dbuf_rele(db, FTAG);
749 } else {
750 mutex_exit(&db->db_mtx);
751 }
752 }
753
754 if (db->db_level != 0)
755 continue;
756 dprintf_dbuf(db, "found buf %s\n", "");
757 if (db->db_blkid < start || db->db_blkid > end)
758 continue;
759
760 /* found a level 0 buffer in the range */
761 if (dbuf_undirty(db, tx))
762 continue;
763
764 mutex_enter(&db->db_mtx);
765 if (db->db_state == DB_UNCACHED ||
766 db->db_state == DB_NOFILL ||
767 db->db_state == DB_EVICTING) {
768 ASSERT(db->db.db_data == NULL);
769 mutex_exit(&db->db_mtx);
770 continue;
771 }
772 if (db->db_state == DB_READ || db->db_state == DB_FILL) {
773 /* will be handled in dbuf_read_done or dbuf_rele */
774 db->db_freed_in_flight = TRUE;
775 mutex_exit(&db->db_mtx);
776 continue;
777 }
778 if (refcount_count(&db->db_holds) == 0) {
779 ASSERT(db->db_buf);
780 dbuf_clear(db);
781 continue;
782 }
783 /* The dbuf is referenced */
784
785 if (db->db_last_dirty != NULL) {
786 dbuf_dirty_record_t *dr = db->db_last_dirty;
787
788 if (dr->dr_txg == txg) {
789 /*
790 * This buffer is "in-use", re-adjust the file
791 * size to reflect that this buffer may
792 * contain new data when we sync.
793 */
794 if (db->db_blkid > dn->dn_maxblkid)
795 dn->dn_maxblkid = db->db_blkid;
796 dbuf_unoverride(dr);
797 } else {
798 /*
799 * This dbuf is not dirty in the open context.
800 * Either uncache it (if its not referenced in
801 * the open context) or reset its contents to
802 * empty.
803 */
804 dbuf_fix_old_data(db, txg);
805 }
806 }
807 /* clear the contents if its cached */
808 if (db->db_state == DB_CACHED) {
809 ASSERT(db->db.db_data != NULL);
810 arc_release(db->db_buf, db);
811 bzero(db->db.db_data, db->db.db_size);
812 arc_buf_freeze(db->db_buf);
813 }
814
815 mutex_exit(&db->db_mtx);
816 }
817 mutex_exit(&dn->dn_dbufs_mtx);
818 }
819
820 static int
821 dbuf_block_freeable(dmu_buf_impl_t *db)
822 {
823 dsl_dataset_t *ds = db->db_objset->os_dsl_dataset;
824 uint64_t birth_txg = 0;
825
826 /*
827 * We don't need any locking to protect db_blkptr:
828 * If it's syncing, then db_last_dirty will be set
829 * so we'll ignore db_blkptr.
830 */
831 ASSERT(MUTEX_HELD(&db->db_mtx));
832 if (db->db_last_dirty)
833 birth_txg = db->db_last_dirty->dr_txg;
834 else if (db->db_blkptr)
835 birth_txg = db->db_blkptr->blk_birth;
836
837 /* If we don't exist or are in a snapshot, we can't be freed */
838 if (birth_txg)
839 return (ds == NULL ||
840 dsl_dataset_block_freeable(ds, birth_txg));
841 else
842 return (FALSE);
843 }
844
845 void
846 dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx)
847 {
848 arc_buf_t *buf, *obuf;
849 int osize = db->db.db_size;
850 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
851
852 ASSERT(db->db_blkid != DB_BONUS_BLKID);
853
854 /* XXX does *this* func really need the lock? */
855 ASSERT(RW_WRITE_HELD(&db->db_dnode->dn_struct_rwlock));
856
857 /*
858 * This call to dbuf_will_dirty() with the dn_struct_rwlock held
859 * is OK, because there can be no other references to the db
860 * when we are changing its size, so no concurrent DB_FILL can
861 * be happening.
862 */
863 /*
864 * XXX we should be doing a dbuf_read, checking the return
865 * value and returning that up to our callers
866 */
867 dbuf_will_dirty(db, tx);
868
869 /* create the data buffer for the new block */
870 buf = arc_buf_alloc(db->db_dnode->dn_objset->os_spa, size, db, type);
871
872 /* copy old block data to the new block */
873 obuf = db->db_buf;
874 bcopy(obuf->b_data, buf->b_data, MIN(osize, size));
875 /* zero the remainder */
876 if (size > osize)
877 bzero((uint8_t *)buf->b_data + osize, size - osize);
878
879 mutex_enter(&db->db_mtx);
880 dbuf_set_data(db, buf);
881 VERIFY(arc_buf_remove_ref(obuf, db) == 1);
882 db->db.db_size = size;
883
884 if (db->db_level == 0) {
885 ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
886 db->db_last_dirty->dt.dl.dr_data = buf;
887 }
888 mutex_exit(&db->db_mtx);
889
890 dnode_willuse_space(db->db_dnode, size-osize, tx);
891 }
892
893 dbuf_dirty_record_t *
894 dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
895 {
896 dnode_t *dn = db->db_dnode;
897 objset_impl_t *os = dn->dn_objset;
898 dbuf_dirty_record_t **drp, *dr;
899 int drop_struct_lock = FALSE;
900 boolean_t do_free_accounting = B_FALSE;
901 int txgoff = tx->tx_txg & TXG_MASK;
902
903 ASSERT(tx->tx_txg != 0);
904 ASSERT(!refcount_is_zero(&db->db_holds));
905 DMU_TX_DIRTY_BUF(tx, db);
906
907 /*
908 * Shouldn't dirty a regular buffer in syncing context. Private
909 * objects may be dirtied in syncing context, but only if they
910 * were already pre-dirtied in open context.
911 * XXX We may want to prohibit dirtying in syncing context even
912 * if they did pre-dirty.
913 */
914 ASSERT(!dmu_tx_is_syncing(tx) ||
915 BP_IS_HOLE(dn->dn_objset->os_rootbp) ||
916 dn->dn_object == DMU_META_DNODE_OBJECT ||
917 dn->dn_objset->os_dsl_dataset == NULL ||
918 dsl_dir_is_private(dn->dn_objset->os_dsl_dataset->ds_dir));
919
920 /*
921 * We make this assert for private objects as well, but after we
922 * check if we're already dirty. They are allowed to re-dirty
923 * in syncing context.
924 */
925 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
926 dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
927 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
928
929 mutex_enter(&db->db_mtx);
930 /*
931 * XXX make this true for indirects too? The problem is that
932 * transactions created with dmu_tx_create_assigned() from
933 * syncing context don't bother holding ahead.
934 */
935 ASSERT(db->db_level != 0 ||
936 db->db_state == DB_CACHED || db->db_state == DB_FILL ||
937 db->db_state == DB_NOFILL);
938
939 mutex_enter(&dn->dn_mtx);
940 /*
941 * Don't set dirtyctx to SYNC if we're just modifying this as we
942 * initialize the objset.
943 */
944 if (dn->dn_dirtyctx == DN_UNDIRTIED &&
945 !BP_IS_HOLE(dn->dn_objset->os_rootbp)) {
946 dn->dn_dirtyctx =
947 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN);
948 ASSERT(dn->dn_dirtyctx_firstset == NULL);
949 dn->dn_dirtyctx_firstset = kmem_alloc(1, KM_SLEEP);
950 }
951 mutex_exit(&dn->dn_mtx);
952
953 /*
954 * If this buffer is already dirty, we're done.
955 */
956 drp = &db->db_last_dirty;
957 ASSERT(*drp == NULL || (*drp)->dr_txg <= tx->tx_txg ||
958 db->db.db_object == DMU_META_DNODE_OBJECT);
959 while ((dr = *drp) != NULL && dr->dr_txg > tx->tx_txg)
960 drp = &dr->dr_next;
961 if (dr && dr->dr_txg == tx->tx_txg) {
962 if (db->db_level == 0 && db->db_blkid != DB_BONUS_BLKID) {
963 /*
964 * If this buffer has already been written out,
965 * we now need to reset its state.
966 */
967 dbuf_unoverride(dr);
968 if (db->db.db_object != DMU_META_DNODE_OBJECT)
969 arc_buf_thaw(db->db_buf);
970 }
971 mutex_exit(&db->db_mtx);
972 return (dr);
973 }
974
975 /*
976 * Only valid if not already dirty.
977 */
978 ASSERT(dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx ==
979 (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN));
980
981 ASSERT3U(dn->dn_nlevels, >, db->db_level);
982 ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) ||
983 dn->dn_phys->dn_nlevels > db->db_level ||
984 dn->dn_next_nlevels[txgoff] > db->db_level ||
985 dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level ||
986 dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level);
987
988 /*
989 * We should only be dirtying in syncing context if it's the
990 * mos, a spa os, or we're initializing the os. However, we are
991 * allowed to dirty in syncing context provided we already
992 * dirtied it in open context. Hence we must make this
993 * assertion only if we're not already dirty.
994 */
995 ASSERT(!dmu_tx_is_syncing(tx) ||
996 os->os_dsl_dataset == NULL ||
997 !dsl_dir_is_private(os->os_dsl_dataset->ds_dir) ||
998 !BP_IS_HOLE(os->os_rootbp));
999 ASSERT(db->db.db_size != 0);
1000
1001 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1002
1003 if (db->db_blkid != DB_BONUS_BLKID) {
1004 /*
1005 * Update the accounting.
1006 * Note: we delay "free accounting" until after we drop
1007 * the db_mtx. This keeps us from grabbing other locks
1008 * (and possibly deadlocking) in bp_get_dasize() while
1009 * also holding the db_mtx.
1010 */
1011 dnode_willuse_space(dn, db->db.db_size, tx);
1012 do_free_accounting = dbuf_block_freeable(db);
1013 }
1014
1015 /*
1016 * If this buffer is dirty in an old transaction group we need
1017 * to make a copy of it so that the changes we make in this
1018 * transaction group won't leak out when we sync the older txg.
1019 */
1020 dr = kmem_zalloc(sizeof (dbuf_dirty_record_t), KM_SLEEP);
1021 if (db->db_level == 0) {
1022 void *data_old = db->db_buf;
1023
1024 if (db->db_state != DB_NOFILL) {
1025 if (db->db_blkid == DB_BONUS_BLKID) {
1026 dbuf_fix_old_data(db, tx->tx_txg);
1027 data_old = db->db.db_data;
1028 } else if (db->db.db_object != DMU_META_DNODE_OBJECT) {
1029 /*
1030 * Release the data buffer from the cache so
1031 * that we can modify it without impacting
1032 * possible other users of this cached data
1033 * block. Note that indirect blocks and
1034 * private objects are not released until the
1035 * syncing state (since they are only modified
1036 * then).
1037 */
1038 arc_release(db->db_buf, db);
1039 dbuf_fix_old_data(db, tx->tx_txg);
1040 data_old = db->db_buf;
1041 }
1042 ASSERT(data_old != NULL);
1043 }
1044 dr->dt.dl.dr_data = data_old;
1045 } else {
1046 mutex_init(&dr->dt.di.dr_mtx, NULL, MUTEX_DEFAULT, NULL);
1047 list_create(&dr->dt.di.dr_children,
1048 sizeof (dbuf_dirty_record_t),
1049 offsetof(dbuf_dirty_record_t, dr_dirty_node));
1050 }
1051 dr->dr_dbuf = db;
1052 dr->dr_txg = tx->tx_txg;
1053 dr->dr_next = *drp;
1054 *drp = dr;
1055
1056 /*
1057 * We could have been freed_in_flight between the dbuf_noread
1058 * and dbuf_dirty. We win, as though the dbuf_noread() had
1059 * happened after the free.
1060 */
1061 if (db->db_level == 0 && db->db_blkid != DB_BONUS_BLKID) {
1062 mutex_enter(&dn->dn_mtx);
1063 dnode_clear_range(dn, db->db_blkid, 1, tx);
1064 mutex_exit(&dn->dn_mtx);
1065 db->db_freed_in_flight = FALSE;
1066 }
1067
1068 /*
1069 * This buffer is now part of this txg
1070 */
1071 dbuf_add_ref(db, (void *)(uintptr_t)tx->tx_txg);
1072 db->db_dirtycnt += 1;
1073 ASSERT3U(db->db_dirtycnt, <=, 3);
1074
1075 mutex_exit(&db->db_mtx);
1076
1077 if (db->db_blkid == DB_BONUS_BLKID) {
1078 mutex_enter(&dn->dn_mtx);
1079 ASSERT(!list_link_active(&dr->dr_dirty_node));
1080 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1081 mutex_exit(&dn->dn_mtx);
1082 dnode_setdirty(dn, tx);
1083 return (dr);
1084 } else if (do_free_accounting) {
1085 blkptr_t *bp = db->db_blkptr;
1086 int64_t willfree = (bp && !BP_IS_HOLE(bp)) ?
1087 bp_get_dasize(os->os_spa, bp) : db->db.db_size;
1088 /*
1089 * This is only a guess -- if the dbuf is dirty
1090 * in a previous txg, we don't know how much
1091 * space it will use on disk yet. We should
1092 * really have the struct_rwlock to access
1093 * db_blkptr, but since this is just a guess,
1094 * it's OK if we get an odd answer.
1095 */
1096 dnode_willuse_space(dn, -willfree, tx);
1097 }
1098
1099 if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
1100 rw_enter(&dn->dn_struct_rwlock, RW_READER);
1101 drop_struct_lock = TRUE;
1102 }
1103
1104 if (db->db_level == 0) {
1105 dnode_new_blkid(dn, db->db_blkid, tx, drop_struct_lock);
1106 ASSERT(dn->dn_maxblkid >= db->db_blkid);
1107 }
1108
1109 if (db->db_level+1 < dn->dn_nlevels) {
1110 dmu_buf_impl_t *parent = db->db_parent;
1111 dbuf_dirty_record_t *di;
1112 int parent_held = FALSE;
1113
1114 if (db->db_parent == NULL || db->db_parent == dn->dn_dbuf) {
1115 int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1116
1117 parent = dbuf_hold_level(dn, db->db_level+1,
1118 db->db_blkid >> epbs, FTAG);
1119 parent_held = TRUE;
1120 }
1121 if (drop_struct_lock)
1122 rw_exit(&dn->dn_struct_rwlock);
1123 ASSERT3U(db->db_level+1, ==, parent->db_level);
1124 di = dbuf_dirty(parent, tx);
1125 if (parent_held)
1126 dbuf_rele(parent, FTAG);
1127
1128 mutex_enter(&db->db_mtx);
1129 /* possible race with dbuf_undirty() */
1130 if (db->db_last_dirty == dr ||
1131 dn->dn_object == DMU_META_DNODE_OBJECT) {
1132 mutex_enter(&di->dt.di.dr_mtx);
1133 ASSERT3U(di->dr_txg, ==, tx->tx_txg);
1134 ASSERT(!list_link_active(&dr->dr_dirty_node));
1135 list_insert_tail(&di->dt.di.dr_children, dr);
1136 mutex_exit(&di->dt.di.dr_mtx);
1137 dr->dr_parent = di;
1138 }
1139 mutex_exit(&db->db_mtx);
1140 } else {
1141 ASSERT(db->db_level+1 == dn->dn_nlevels);
1142 ASSERT(db->db_blkid < dn->dn_nblkptr);
1143 ASSERT(db->db_parent == NULL ||
1144 db->db_parent == db->db_dnode->dn_dbuf);
1145 mutex_enter(&dn->dn_mtx);
1146 ASSERT(!list_link_active(&dr->dr_dirty_node));
1147 list_insert_tail(&dn->dn_dirty_records[txgoff], dr);
1148 mutex_exit(&dn->dn_mtx);
1149 if (drop_struct_lock)
1150 rw_exit(&dn->dn_struct_rwlock);
1151 }
1152
1153 dnode_setdirty(dn, tx);
1154 return (dr);
1155 }
1156
1157 static int
1158 dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1159 {
1160 dnode_t *dn = db->db_dnode;
1161 uint64_t txg = tx->tx_txg;
1162 dbuf_dirty_record_t *dr, **drp;
1163
1164 ASSERT(txg != 0);
1165 ASSERT(db->db_blkid != DB_BONUS_BLKID);
1166
1167 mutex_enter(&db->db_mtx);
1168
1169 /*
1170 * If this buffer is not dirty, we're done.
1171 */
1172 for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next)
1173 if (dr->dr_txg <= txg)
1174 break;
1175 if (dr == NULL || dr->dr_txg < txg) {
1176 mutex_exit(&db->db_mtx);
1177 return (0);
1178 }
1179 ASSERT(dr->dr_txg == txg);
1180
1181 /*
1182 * If this buffer is currently held, we cannot undirty
1183 * it, since one of the current holders may be in the
1184 * middle of an update. Note that users of dbuf_undirty()
1185 * should not place a hold on the dbuf before the call.
1186 */
1187 if (refcount_count(&db->db_holds) > db->db_dirtycnt) {
1188 mutex_exit(&db->db_mtx);
1189 /* Make sure we don't toss this buffer at sync phase */
1190 mutex_enter(&dn->dn_mtx);
1191 dnode_clear_range(dn, db->db_blkid, 1, tx);
1192 mutex_exit(&dn->dn_mtx);
1193 return (0);
1194 }
1195
1196 dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
1197
1198 ASSERT(db->db.db_size != 0);
1199
1200 /* XXX would be nice to fix up dn_towrite_space[] */
1201
1202 *drp = dr->dr_next;
1203
1204 if (dr->dr_parent) {
1205 mutex_enter(&dr->dr_parent->dt.di.dr_mtx);
1206 list_remove(&dr->dr_parent->dt.di.dr_children, dr);
1207 mutex_exit(&dr->dr_parent->dt.di.dr_mtx);
1208 } else if (db->db_level+1 == dn->dn_nlevels) {
1209 ASSERT(db->db_blkptr == NULL || db->db_parent == dn->dn_dbuf);
1210 mutex_enter(&dn->dn_mtx);
1211 list_remove(&dn->dn_dirty_records[txg & TXG_MASK], dr);
1212 mutex_exit(&dn->dn_mtx);
1213 }
1214
1215 if (db->db_level == 0) {
1216 if (db->db_state != DB_NOFILL) {
1217 dbuf_unoverride(dr);
1218
1219 ASSERT(db->db_buf != NULL);
1220 ASSERT(dr->dt.dl.dr_data != NULL);
1221 if (dr->dt.dl.dr_data != db->db_buf)
1222 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data,
1223 db) == 1);
1224 }
1225 } else {
1226 ASSERT(db->db_buf != NULL);
1227 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
1228 mutex_destroy(&dr->dt.di.dr_mtx);
1229 list_destroy(&dr->dt.di.dr_children);
1230 }
1231 kmem_free(dr, sizeof (dbuf_dirty_record_t));
1232
1233 ASSERT(db->db_dirtycnt > 0);
1234 db->db_dirtycnt -= 1;
1235
1236 if (refcount_remove(&db->db_holds, (void *)(uintptr_t)txg) == 0) {
1237 arc_buf_t *buf = db->db_buf;
1238
1239 ASSERT(arc_released(buf));
1240 dbuf_set_data(db, NULL);
1241 VERIFY(arc_buf_remove_ref(buf, db) == 1);
1242 dbuf_evict(db);
1243 return (1);
1244 }
1245
1246 mutex_exit(&db->db_mtx);
1247 return (0);
1248 }
1249
1250 #pragma weak dmu_buf_will_dirty = dbuf_will_dirty
1251 void
1252 dbuf_will_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
1253 {
1254 int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH;
1255
1256 ASSERT(tx->tx_txg != 0);
1257 ASSERT(!refcount_is_zero(&db->db_holds));
1258
1259 if (RW_WRITE_HELD(&db->db_dnode->dn_struct_rwlock))
1260 rf |= DB_RF_HAVESTRUCT;
1261 (void) dbuf_read(db, NULL, rf);
1262 (void) dbuf_dirty(db, tx);
1263 }
1264
1265 void
1266 dmu_buf_will_not_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1267 {
1268 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1269
1270 db->db_state = DB_NOFILL;
1271
1272 dmu_buf_will_fill(db_fake, tx);
1273 }
1274
1275 void
1276 dmu_buf_will_fill(dmu_buf_t *db_fake, dmu_tx_t *tx)
1277 {
1278 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1279
1280 ASSERT(db->db_blkid != DB_BONUS_BLKID);
1281 ASSERT(tx->tx_txg != 0);
1282 ASSERT(db->db_level == 0);
1283 ASSERT(!refcount_is_zero(&db->db_holds));
1284
1285 ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT ||
1286 dmu_tx_private_ok(tx));
1287
1288 dbuf_noread(db);
1289 (void) dbuf_dirty(db, tx);
1290 }
1291
1292 #pragma weak dmu_buf_fill_done = dbuf_fill_done
1293 /* ARGSUSED */
1294 void
1295 dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx)
1296 {
1297 mutex_enter(&db->db_mtx);
1298 DBUF_VERIFY(db);
1299
1300 if (db->db_state == DB_FILL) {
1301 if (db->db_level == 0 && db->db_freed_in_flight) {
1302 ASSERT(db->db_blkid != DB_BONUS_BLKID);
1303 /* we were freed while filling */
1304 /* XXX dbuf_undirty? */
1305 bzero(db->db.db_data, db->db.db_size);
1306 db->db_freed_in_flight = FALSE;
1307 }
1308 db->db_state = DB_CACHED;
1309 cv_broadcast(&db->db_changed);
1310 }
1311 mutex_exit(&db->db_mtx);
1312 }
1313
1314 /*
1315 * "Clear" the contents of this dbuf. This will mark the dbuf
1316 * EVICTING and clear *most* of its references. Unfortunetely,
1317 * when we are not holding the dn_dbufs_mtx, we can't clear the
1318 * entry in the dn_dbufs list. We have to wait until dbuf_destroy()
1319 * in this case. For callers from the DMU we will usually see:
1320 * dbuf_clear()->arc_buf_evict()->dbuf_do_evict()->dbuf_destroy()
1321 * For the arc callback, we will usually see:
1322 * dbuf_do_evict()->dbuf_clear();dbuf_destroy()
1323 * Sometimes, though, we will get a mix of these two:
1324 * DMU: dbuf_clear()->arc_buf_evict()
1325 * ARC: dbuf_do_evict()->dbuf_destroy()
1326 */
1327 void
1328 dbuf_clear(dmu_buf_impl_t *db)
1329 {
1330 dnode_t *dn = db->db_dnode;
1331 dmu_buf_impl_t *parent = db->db_parent;
1332 dmu_buf_impl_t *dndb = dn->dn_dbuf;
1333 int dbuf_gone = FALSE;
1334
1335 ASSERT(MUTEX_HELD(&db->db_mtx));
1336 ASSERT(refcount_is_zero(&db->db_holds));
1337
1338 dbuf_evict_user(db);
1339
1340 if (db->db_state == DB_CACHED) {
1341 ASSERT(db->db.db_data != NULL);
1342 if (db->db_blkid == DB_BONUS_BLKID) {
1343 zio_buf_free(db->db.db_data, DN_MAX_BONUSLEN);
1344 arc_space_return(DN_MAX_BONUSLEN);
1345 }
1346 db->db.db_data = NULL;
1347 db->db_state = DB_UNCACHED;
1348 }
1349
1350 ASSERT(db->db_state == DB_UNCACHED || db->db_state == DB_NOFILL);
1351 ASSERT(db->db_data_pending == NULL);
1352
1353 db->db_state = DB_EVICTING;
1354 db->db_blkptr = NULL;
1355
1356 if (db->db_blkid != DB_BONUS_BLKID && MUTEX_HELD(&dn->dn_dbufs_mtx)) {
1357 list_remove(&dn->dn_dbufs, db);
1358 dnode_rele(dn, db);
1359 db->db_dnode = NULL;
1360 }
1361
1362 if (db->db_buf)
1363 dbuf_gone = arc_buf_evict(db->db_buf);
1364
1365 if (!dbuf_gone)
1366 mutex_exit(&db->db_mtx);
1367
1368 /*
1369 * If this dbuf is referened from an indirect dbuf,
1370 * decrement the ref count on the indirect dbuf.
1371 */
1372 if (parent && parent != dndb)
1373 dbuf_rele(parent, db);
1374 }
1375
1376 static int
1377 dbuf_findbp(dnode_t *dn, int level, uint64_t blkid, int fail_sparse,
1378 dmu_buf_impl_t **parentp, blkptr_t **bpp)
1379 {
1380 int nlevels, epbs;
1381
1382 *parentp = NULL;
1383 *bpp = NULL;
1384
1385 ASSERT(blkid != DB_BONUS_BLKID);
1386
1387 if (dn->dn_phys->dn_nlevels == 0)
1388 nlevels = 1;
1389 else
1390 nlevels = dn->dn_phys->dn_nlevels;
1391
1392 epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
1393
1394 ASSERT3U(level * epbs, <, 64);
1395 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1396 if (level >= nlevels ||
1397 (blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))) {
1398 /* the buffer has no parent yet */
1399 return (ENOENT);
1400 } else if (level < nlevels-1) {
1401 /* this block is referenced from an indirect block */
1402 int err = dbuf_hold_impl(dn, level+1,
1403 blkid >> epbs, fail_sparse, NULL, parentp);
1404 if (err)
1405 return (err);
1406 err = dbuf_read(*parentp, NULL,
1407 (DB_RF_HAVESTRUCT | DB_RF_NOPREFETCH | DB_RF_CANFAIL));
1408 if (err) {
1409 dbuf_rele(*parentp, NULL);
1410 *parentp = NULL;
1411 return (err);
1412 }
1413 *bpp = ((blkptr_t *)(*parentp)->db.db_data) +
1414 (blkid & ((1ULL << epbs) - 1));
1415 return (0);
1416 } else {
1417 /* the block is referenced from the dnode */
1418 ASSERT3U(level, ==, nlevels-1);
1419 ASSERT(dn->dn_phys->dn_nblkptr == 0 ||
1420 blkid < dn->dn_phys->dn_nblkptr);
1421 if (dn->dn_dbuf) {
1422 dbuf_add_ref(dn->dn_dbuf, NULL);
1423 *parentp = dn->dn_dbuf;
1424 }
1425 *bpp = &dn->dn_phys->dn_blkptr[blkid];
1426 return (0);
1427 }
1428 }
1429
1430 static dmu_buf_impl_t *
1431 dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid,
1432 dmu_buf_impl_t *parent, blkptr_t *blkptr)
1433 {
1434 objset_impl_t *os = dn->dn_objset;
1435 dmu_buf_impl_t *db, *odb;
1436
1437 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1438 ASSERT(dn->dn_type != DMU_OT_NONE);
1439
1440 db = kmem_cache_alloc(dbuf_cache, KM_SLEEP);
1441
1442 db->db_objset = os;
1443 db->db.db_object = dn->dn_object;
1444 db->db_level = level;
1445 db->db_blkid = blkid;
1446 db->db_last_dirty = NULL;
1447 db->db_dirtycnt = 0;
1448 db->db_dnode = dn;
1449 db->db_parent = parent;
1450 db->db_blkptr = blkptr;
1451
1452 db->db_user_ptr = NULL;
1453 db->db_user_data_ptr_ptr = NULL;
1454 db->db_evict_func = NULL;
1455 db->db_immediate_evict = 0;
1456 db->db_freed_in_flight = 0;
1457
1458 if (blkid == DB_BONUS_BLKID) {
1459 ASSERT3P(parent, ==, dn->dn_dbuf);
1460 db->db.db_size = DN_MAX_BONUSLEN -
1461 (dn->dn_nblkptr-1) * sizeof (blkptr_t);
1462 ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
1463 db->db.db_offset = DB_BONUS_BLKID;
1464 db->db_state = DB_UNCACHED;
1465 /* the bonus dbuf is not placed in the hash table */
1466 arc_space_consume(sizeof (dmu_buf_impl_t));
1467 return (db);
1468 } else {
1469 int blocksize =
1470 db->db_level ? 1<<dn->dn_indblkshift : dn->dn_datablksz;
1471 db->db.db_size = blocksize;
1472 db->db.db_offset = db->db_blkid * blocksize;
1473 }
1474
1475 /*
1476 * Hold the dn_dbufs_mtx while we get the new dbuf
1477 * in the hash table *and* added to the dbufs list.
1478 * This prevents a possible deadlock with someone
1479 * trying to look up this dbuf before its added to the
1480 * dn_dbufs list.
1481 */
1482 mutex_enter(&dn->dn_dbufs_mtx);
1483 db->db_state = DB_EVICTING;
1484 if ((odb = dbuf_hash_insert(db)) != NULL) {
1485 /* someone else inserted it first */
1486 kmem_cache_free(dbuf_cache, db);
1487 mutex_exit(&dn->dn_dbufs_mtx);
1488 return (odb);
1489 }
1490 list_insert_head(&dn->dn_dbufs, db);
1491 db->db_state = DB_UNCACHED;
1492 mutex_exit(&dn->dn_dbufs_mtx);
1493 arc_space_consume(sizeof (dmu_buf_impl_t));
1494
1495 if (parent && parent != dn->dn_dbuf)
1496 dbuf_add_ref(parent, db);
1497
1498 ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT ||
1499 refcount_count(&dn->dn_holds) > 0);
1500 (void) refcount_add(&dn->dn_holds, db);
1501
1502 dprintf_dbuf(db, "db=%p\n", db);
1503
1504 return (db);
1505 }
1506
1507 static int
1508 dbuf_do_evict(void *private)
1509 {
1510 arc_buf_t *buf = private;
1511 dmu_buf_impl_t *db = buf->b_private;
1512
1513 if (!MUTEX_HELD(&db->db_mtx))
1514 mutex_enter(&db->db_mtx);
1515
1516 ASSERT(refcount_is_zero(&db->db_holds));
1517
1518 if (db->db_state != DB_EVICTING) {
1519 ASSERT(db->db_state == DB_CACHED);
1520 DBUF_VERIFY(db);
1521 db->db_buf = NULL;
1522 dbuf_evict(db);
1523 } else {
1524 mutex_exit(&db->db_mtx);
1525 dbuf_destroy(db);
1526 }
1527 return (0);
1528 }
1529
1530 static void
1531 dbuf_destroy(dmu_buf_impl_t *db)
1532 {
1533 ASSERT(refcount_is_zero(&db->db_holds));
1534
1535 if (db->db_blkid != DB_BONUS_BLKID) {
1536 /*
1537 * If this dbuf is still on the dn_dbufs list,
1538 * remove it from that list.
1539 */
1540 if (db->db_dnode) {
1541 dnode_t *dn = db->db_dnode;
1542
1543 mutex_enter(&dn->dn_dbufs_mtx);
1544 list_remove(&dn->dn_dbufs, db);
1545 mutex_exit(&dn->dn_dbufs_mtx);
1546
1547 dnode_rele(dn, db);
1548 db->db_dnode = NULL;
1549 }
1550 dbuf_hash_remove(db);
1551 }
1552 db->db_parent = NULL;
1553 db->db_buf = NULL;
1554
1555 ASSERT(!list_link_active(&db->db_link));
1556 ASSERT(db->db.db_data == NULL);
1557 ASSERT(db->db_hash_next == NULL);
1558 ASSERT(db->db_blkptr == NULL);
1559 ASSERT(db->db_data_pending == NULL);
1560
1561 kmem_cache_free(dbuf_cache, db);
1562 arc_space_return(sizeof (dmu_buf_impl_t));
1563 }
1564
1565 void
1566 dbuf_prefetch(dnode_t *dn, uint64_t blkid)
1567 {
1568 dmu_buf_impl_t *db = NULL;
1569 blkptr_t *bp = NULL;
1570
1571 ASSERT(blkid != DB_BONUS_BLKID);
1572 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1573
1574 if (dnode_block_freed(dn, blkid))
1575 return;
1576
1577 /* dbuf_find() returns with db_mtx held */
1578 if (db = dbuf_find(dn, 0, blkid)) {
1579 if (refcount_count(&db->db_holds) > 0) {
1580 /*
1581 * This dbuf is active. We assume that it is
1582 * already CACHED, or else about to be either
1583 * read or filled.
1584 */
1585 mutex_exit(&db->db_mtx);
1586 return;
1587 }
1588 mutex_exit(&db->db_mtx);
1589 db = NULL;
1590 }
1591
1592 if (dbuf_findbp(dn, 0, blkid, TRUE, &db, &bp) == 0) {
1593 if (bp && !BP_IS_HOLE(bp)) {
1594 arc_buf_t *pbuf;
1595 uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH;
1596 zbookmark_t zb;
1597 zb.zb_objset = dn->dn_objset->os_dsl_dataset ?
1598 dn->dn_objset->os_dsl_dataset->ds_object : 0;
1599 zb.zb_object = dn->dn_object;
1600 zb.zb_level = 0;
1601 zb.zb_blkid = blkid;
1602
1603 if (db)
1604 pbuf = db->db_buf;
1605 else
1606 pbuf = dn->dn_objset->os_phys_buf;
1607
1608 (void) arc_read(NULL, dn->dn_objset->os_spa,
1609 bp, pbuf, NULL, NULL, ZIO_PRIORITY_ASYNC_READ,
1610 ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
1611 &aflags, &zb);
1612 }
1613 if (db)
1614 dbuf_rele(db, NULL);
1615 }
1616 }
1617
1618 /*
1619 * Returns with db_holds incremented, and db_mtx not held.
1620 * Note: dn_struct_rwlock must be held.
1621 */
1622 int
1623 dbuf_hold_impl(dnode_t *dn, uint8_t level, uint64_t blkid, int fail_sparse,
1624 void *tag, dmu_buf_impl_t **dbp)
1625 {
1626 dmu_buf_impl_t *db, *parent = NULL;
1627
1628 ASSERT(blkid != DB_BONUS_BLKID);
1629 ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
1630 ASSERT3U(dn->dn_nlevels, >, level);
1631
1632 *dbp = NULL;
1633 top:
1634 /* dbuf_find() returns with db_mtx held */
1635 db = dbuf_find(dn, level, blkid);
1636
1637 if (db == NULL) {
1638 blkptr_t *bp = NULL;
1639 int err;
1640
1641 ASSERT3P(parent, ==, NULL);
1642 err = dbuf_findbp(dn, level, blkid, fail_sparse, &parent, &bp);
1643 if (fail_sparse) {
1644 if (err == 0 && bp && BP_IS_HOLE(bp))
1645 err = ENOENT;
1646 if (err) {
1647 if (parent)
1648 dbuf_rele(parent, NULL);
1649 return (err);
1650 }
1651 }
1652 if (err && err != ENOENT)
1653 return (err);
1654 db = dbuf_create(dn, level, blkid, parent, bp);
1655 }
1656
1657 if (db->db_buf && refcount_is_zero(&db->db_holds)) {
1658 arc_buf_add_ref(db->db_buf, db);
1659 if (db->db_buf->b_data == NULL) {
1660 dbuf_clear(db);
1661 if (parent) {
1662 dbuf_rele(parent, NULL);
1663 parent = NULL;
1664 }
1665 goto top;
1666 }
1667 ASSERT3P(db->db.db_data, ==, db->db_buf->b_data);
1668 }
1669
1670 ASSERT(db->db_buf == NULL || arc_referenced(db->db_buf));
1671
1672 /*
1673 * If this buffer is currently syncing out, and we are are
1674 * still referencing it from db_data, we need to make a copy
1675 * of it in case we decide we want to dirty it again in this txg.
1676 */
1677 if (db->db_level == 0 && db->db_blkid != DB_BONUS_BLKID &&
1678 dn->dn_object != DMU_META_DNODE_OBJECT &&
1679 db->db_state == DB_CACHED && db->db_data_pending) {
1680 dbuf_dirty_record_t *dr = db->db_data_pending;
1681
1682 if (dr->dt.dl.dr_data == db->db_buf) {
1683 arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
1684
1685 dbuf_set_data(db,
1686 arc_buf_alloc(db->db_dnode->dn_objset->os_spa,
1687 db->db.db_size, db, type));
1688 bcopy(dr->dt.dl.dr_data->b_data, db->db.db_data,
1689 db->db.db_size);
1690 }
1691 }
1692
1693 (void) refcount_add(&db->db_holds, tag);
1694 dbuf_update_data(db);
1695 DBUF_VERIFY(db);
1696 mutex_exit(&db->db_mtx);
1697
1698 /* NOTE: we can't rele the parent until after we drop the db_mtx */
1699 if (parent)
1700 dbuf_rele(parent, NULL);
1701
1702 ASSERT3P(db->db_dnode, ==, dn);
1703 ASSERT3U(db->db_blkid, ==, blkid);
1704 ASSERT3U(db->db_level, ==, level);
1705 *dbp = db;
1706
1707 return (0);
1708 }
1709
1710 dmu_buf_impl_t *
1711 dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag)
1712 {
1713 dmu_buf_impl_t *db;
1714 int err = dbuf_hold_impl(dn, 0, blkid, FALSE, tag, &db);
1715 return (err ? NULL : db);
1716 }
1717
1718 dmu_buf_impl_t *
1719 dbuf_hold_level(dnode_t *dn, int level, uint64_t blkid, void *tag)
1720 {
1721 dmu_buf_impl_t *db;
1722 int err = dbuf_hold_impl(dn, level, blkid, FALSE, tag, &db);
1723 return (err ? NULL : db);
1724 }
1725
1726 void
1727 dbuf_create_bonus(dnode_t *dn)
1728 {
1729 ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock));
1730
1731 ASSERT(dn->dn_bonus == NULL);
1732 dn->dn_bonus = dbuf_create(dn, 0, DB_BONUS_BLKID, dn->dn_dbuf, NULL);
1733 }
1734
1735 #pragma weak dmu_buf_add_ref = dbuf_add_ref
1736 void
1737 dbuf_add_ref(dmu_buf_impl_t *db, void *tag)
1738 {
1739 int64_t holds = refcount_add(&db->db_holds, tag);
1740 ASSERT(holds > 1);
1741 }
1742
1743 #pragma weak dmu_buf_rele = dbuf_rele
1744 void
1745 dbuf_rele(dmu_buf_impl_t *db, void *tag)
1746 {
1747 int64_t holds;
1748
1749 mutex_enter(&db->db_mtx);
1750 DBUF_VERIFY(db);
1751
1752 holds = refcount_remove(&db->db_holds, tag);
1753 ASSERT(holds >= 0);
1754
1755 /*
1756 * We can't freeze indirects if there is a possibility that they
1757 * may be modified in the current syncing context.
1758 */
1759 if (db->db_buf && holds == (db->db_level == 0 ? db->db_dirtycnt : 0))
1760 arc_buf_freeze(db->db_buf);
1761
1762 if (holds == db->db_dirtycnt &&
1763 db->db_level == 0 && db->db_immediate_evict)
1764 dbuf_evict_user(db);
1765
1766 if (holds == 0) {
1767 if (db->db_blkid == DB_BONUS_BLKID) {
1768 mutex_exit(&db->db_mtx);
1769 dnode_rele(db->db_dnode, db);
1770 } else if (db->db_buf == NULL) {
1771 /*
1772 * This is a special case: we never associated this
1773 * dbuf with any data allocated from the ARC.
1774 */
1775 ASSERT(db->db_state == DB_UNCACHED ||
1776 db->db_state == DB_NOFILL);
1777 dbuf_evict(db);
1778 } else if (arc_released(db->db_buf)) {
1779 arc_buf_t *buf = db->db_buf;
1780 /*
1781 * This dbuf has anonymous data associated with it.
1782 */
1783 dbuf_set_data(db, NULL);
1784 VERIFY(arc_buf_remove_ref(buf, db) == 1);
1785 dbuf_evict(db);
1786 } else {
1787 VERIFY(arc_buf_remove_ref(db->db_buf, db) == 0);
1788 if (!DBUF_IS_CACHEABLE(db))
1789 dbuf_clear(db);
1790 else
1791 mutex_exit(&db->db_mtx);
1792 }
1793 } else {
1794 mutex_exit(&db->db_mtx);
1795 }
1796 }
1797
1798 #pragma weak dmu_buf_refcount = dbuf_refcount
1799 uint64_t
1800 dbuf_refcount(dmu_buf_impl_t *db)
1801 {
1802 return (refcount_count(&db->db_holds));
1803 }
1804
1805 void *
1806 dmu_buf_set_user(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr,
1807 dmu_buf_evict_func_t *evict_func)
1808 {
1809 return (dmu_buf_update_user(db_fake, NULL, user_ptr,
1810 user_data_ptr_ptr, evict_func));
1811 }
1812
1813 void *
1814 dmu_buf_set_user_ie(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr,
1815 dmu_buf_evict_func_t *evict_func)
1816 {
1817 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1818
1819 db->db_immediate_evict = TRUE;
1820 return (dmu_buf_update_user(db_fake, NULL, user_ptr,
1821 user_data_ptr_ptr, evict_func));
1822 }
1823
1824 void *
1825 dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr, void *user_ptr,
1826 void *user_data_ptr_ptr, dmu_buf_evict_func_t *evict_func)
1827 {
1828 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1829 ASSERT(db->db_level == 0);
1830
1831 ASSERT((user_ptr == NULL) == (evict_func == NULL));
1832
1833 mutex_enter(&db->db_mtx);
1834
1835 if (db->db_user_ptr == old_user_ptr) {
1836 db->db_user_ptr = user_ptr;
1837 db->db_user_data_ptr_ptr = user_data_ptr_ptr;
1838 db->db_evict_func = evict_func;
1839
1840 dbuf_update_data(db);
1841 } else {
1842 old_user_ptr = db->db_user_ptr;
1843 }
1844
1845 mutex_exit(&db->db_mtx);
1846 return (old_user_ptr);
1847 }
1848
1849 void *
1850 dmu_buf_get_user(dmu_buf_t *db_fake)
1851 {
1852 dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
1853 ASSERT(!refcount_is_zero(&db->db_holds));
1854
1855 return (db->db_user_ptr);
1856 }
1857
1858 static void
1859 dbuf_check_blkptr(dnode_t *dn, dmu_buf_impl_t *db)
1860 {
1861 /* ASSERT(dmu_tx_is_syncing(tx) */
1862 ASSERT(MUTEX_HELD(&db->db_mtx));
1863
1864 if (db->db_blkptr != NULL)
1865 return;
1866
1867 if (db->db_level == dn->dn_phys->dn_nlevels-1) {
1868 /*
1869 * This buffer was allocated at a time when there was
1870 * no available blkptrs from the dnode, or it was
1871 * inappropriate to hook it in (i.e., nlevels mis-match).
1872 */
1873 ASSERT(db->db_blkid < dn->dn_phys->dn_nblkptr);
1874 ASSERT(db->db_parent == NULL);
1875 db->db_parent = dn->dn_dbuf;
1876 db->db_blkptr = &dn->dn_phys->dn_blkptr[db->db_blkid];
1877 DBUF_VERIFY(db);
1878 } else {
1879 dmu_buf_impl_t *parent = db->db_parent;
1880 int epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
1881
1882 ASSERT(dn->dn_phys->dn_nlevels > 1);
1883 if (parent == NULL) {
1884 mutex_exit(&db->db_mtx);
1885 rw_enter(&dn->dn_struct_rwlock, RW_READER);
1886 (void) dbuf_hold_impl(dn, db->db_level+1,
1887 db->db_blkid >> epbs, FALSE, db, &parent);
1888 rw_exit(&dn->dn_struct_rwlock);
1889 mutex_enter(&db->db_mtx);
1890 db->db_parent = parent;
1891 }
1892 db->db_blkptr = (blkptr_t *)parent->db.db_data +
1893 (db->db_blkid & ((1ULL << epbs) - 1));
1894 DBUF_VERIFY(db);
1895 }
1896 }
1897
1898 static void
1899 dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
1900 {
1901 dmu_buf_impl_t *db = dr->dr_dbuf;
1902 dnode_t *dn = db->db_dnode;
1903 zio_t *zio;
1904
1905 ASSERT(dmu_tx_is_syncing(tx));
1906
1907 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
1908
1909 mutex_enter(&db->db_mtx);
1910
1911 ASSERT(db->db_level > 0);
1912 DBUF_VERIFY(db);
1913
1914 if (db->db_buf == NULL) {
1915 mutex_exit(&db->db_mtx);
1916 (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED);
1917 mutex_enter(&db->db_mtx);
1918 }
1919 ASSERT3U(db->db_state, ==, DB_CACHED);
1920 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
1921 ASSERT(db->db_buf != NULL);
1922
1923 dbuf_check_blkptr(dn, db);
1924
1925 db->db_data_pending = dr;
1926
1927 mutex_exit(&db->db_mtx);
1928 dbuf_write(dr, db->db_buf, tx);
1929
1930 zio = dr->dr_zio;
1931 mutex_enter(&dr->dt.di.dr_mtx);
1932 dbuf_sync_list(&dr->dt.di.dr_children, tx);
1933 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
1934 mutex_exit(&dr->dt.di.dr_mtx);
1935 zio_nowait(zio);
1936 }
1937
1938 static void
1939 dbuf_sync_leaf(dbuf_dirty_record_t *dr, dmu_tx_t *tx)
1940 {
1941 arc_buf_t **datap = &dr->dt.dl.dr_data;
1942 dmu_buf_impl_t *db = dr->dr_dbuf;
1943 dnode_t *dn = db->db_dnode;
1944 objset_impl_t *os = dn->dn_objset;
1945 uint64_t txg = tx->tx_txg;
1946 int blksz;
1947
1948 ASSERT(dmu_tx_is_syncing(tx));
1949
1950 dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr);
1951
1952 mutex_enter(&db->db_mtx);
1953 /*
1954 * To be synced, we must be dirtied. But we
1955 * might have been freed after the dirty.
1956 */
1957 if (db->db_state == DB_UNCACHED) {
1958 /* This buffer has been freed since it was dirtied */
1959 ASSERT(db->db.db_data == NULL);
1960 } else if (db->db_state == DB_FILL) {
1961 /* This buffer was freed and is now being re-filled */
1962 ASSERT(db->db.db_data != dr->dt.dl.dr_data);
1963 } else {
1964 ASSERT(db->db_state == DB_CACHED || db->db_state == DB_NOFILL);
1965 }
1966 DBUF_VERIFY(db);
1967
1968 /*
1969 * If this is a bonus buffer, simply copy the bonus data into the
1970 * dnode. It will be written out when the dnode is synced (and it
1971 * will be synced, since it must have been dirty for dbuf_sync to
1972 * be called).
1973 */
1974 if (db->db_blkid == DB_BONUS_BLKID) {
1975 dbuf_dirty_record_t **drp;
1976
1977 ASSERT(*datap != NULL);
1978 ASSERT3U(db->db_level, ==, 0);
1979 ASSERT3U(dn->dn_phys->dn_bonuslen, <=, DN_MAX_BONUSLEN);
1980 bcopy(*datap, DN_BONUS(dn->dn_phys), dn->dn_phys->dn_bonuslen);
1981 if (*datap != db->db.db_data) {
1982 zio_buf_free(*datap, DN_MAX_BONUSLEN);
1983 arc_space_return(DN_MAX_BONUSLEN);
1984 }
1985 db->db_data_pending = NULL;
1986 drp = &db->db_last_dirty;
1987 while (*drp != dr)
1988 drp = &(*drp)->dr_next;
1989 ASSERT(dr->dr_next == NULL);
1990 *drp = dr->dr_next;
1991 kmem_free(dr, sizeof (dbuf_dirty_record_t));
1992 ASSERT(db->db_dirtycnt > 0);
1993 db->db_dirtycnt -= 1;
1994 mutex_exit(&db->db_mtx);
1995 dbuf_rele(db, (void *)(uintptr_t)txg);
1996 return;
1997 }
1998
1999 /*
2000 * This function may have dropped the db_mtx lock allowing a dmu_sync
2001 * operation to sneak in. As a result, we need to ensure that we
2002 * don't check the dr_override_state until we have returned from
2003 * dbuf_check_blkptr.
2004 */
2005 dbuf_check_blkptr(dn, db);
2006
2007 /*
2008 * If this buffer is in the middle of an immdiate write,
2009 * wait for the synchronous IO to complete.
2010 */
2011 while (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC) {
2012 ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT);
2013 cv_wait(&db->db_changed, &db->db_mtx);
2014 ASSERT(dr->dt.dl.dr_override_state != DR_NOT_OVERRIDDEN);
2015 }
2016
2017 /*
2018 * If this dbuf has already been written out via an immediate write,
2019 * just complete the write by copying over the new block pointer and
2020 * updating the accounting via the write-completion functions.
2021 */
2022 if (dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
2023 zio_t zio_fake;
2024
2025 zio_fake.io_private = &db;
2026 zio_fake.io_error = 0;
2027 zio_fake.io_bp = db->db_blkptr;
2028 zio_fake.io_bp_orig = *db->db_blkptr;
2029 zio_fake.io_txg = txg;
2030 zio_fake.io_flags = 0;
2031
2032 *db->db_blkptr = dr->dt.dl.dr_overridden_by;
2033 dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
2034 db->db_data_pending = dr;
2035 dr->dr_zio = &zio_fake;
2036 mutex_exit(&db->db_mtx);
2037
2038 ASSERT(!DVA_EQUAL(BP_IDENTITY(zio_fake.io_bp),
2039 BP_IDENTITY(&zio_fake.io_bp_orig)) ||
2040 BP_IS_HOLE(zio_fake.io_bp));
2041
2042 if (BP_IS_OLDER(&zio_fake.io_bp_orig, txg))
2043 (void) dsl_dataset_block_kill(os->os_dsl_dataset,
2044 &zio_fake.io_bp_orig, dn->dn_zio, tx);
2045
2046 dbuf_write_ready(&zio_fake, db->db_buf, db);
2047 dbuf_write_done(&zio_fake, db->db_buf, db);
2048
2049 return;
2050 }
2051
2052 if (db->db_state != DB_NOFILL) {
2053 blksz = arc_buf_size(*datap);
2054
2055 if (dn->dn_object != DMU_META_DNODE_OBJECT) {
2056 /*
2057 * If this buffer is currently "in use" (i.e., there
2058 * are active holds and db_data still references it),
2059 * then make a copy before we start the write so that
2060 * any modifications from the open txg will not leak
2061 * into this write.
2062 *
2063 * NOTE: this copy does not need to be made for
2064 * objects only modified in the syncing context (e.g.
2065 * DNONE_DNODE blocks).
2066 */
2067 if (refcount_count(&db->db_holds) > 1 &&
2068 *datap == db->db_buf) {
2069 arc_buf_contents_t type =
2070 DBUF_GET_BUFC_TYPE(db);
2071 *datap =
2072 arc_buf_alloc(os->os_spa, blksz, db, type);
2073 bcopy(db->db.db_data, (*datap)->b_data, blksz);
2074 }
2075 }
2076
2077 ASSERT(*datap != NULL);
2078 }
2079 db->db_data_pending = dr;
2080
2081 mutex_exit(&db->db_mtx);
2082
2083 dbuf_write(dr, *datap, tx);
2084
2085 ASSERT(!list_link_active(&dr->dr_dirty_node));
2086 if (dn->dn_object == DMU_META_DNODE_OBJECT)
2087 list_insert_tail(&dn->dn_dirty_records[txg&TXG_MASK], dr);
2088 else
2089 zio_nowait(dr->dr_zio);
2090 }
2091
2092 void
2093 dbuf_sync_list(list_t *list, dmu_tx_t *tx)
2094 {
2095 dbuf_dirty_record_t *dr;
2096
2097 while (dr = list_head(list)) {
2098 if (dr->dr_zio != NULL) {
2099 /*
2100 * If we find an already initialized zio then we
2101 * are processing the meta-dnode, and we have finished.
2102 * The dbufs for all dnodes are put back on the list
2103 * during processing, so that we can zio_wait()
2104 * these IOs after initiating all child IOs.
2105 */
2106 ASSERT3U(dr->dr_dbuf->db.db_object, ==,
2107 DMU_META_DNODE_OBJECT);
2108 break;
2109 }
2110 list_remove(list, dr);
2111 if (dr->dr_dbuf->db_level > 0)
2112 dbuf_sync_indirect(dr, tx);
2113 else
2114 dbuf_sync_leaf(dr, tx);
2115 }
2116 }
2117
2118 static void
2119 dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx)
2120 {
2121 dmu_buf_impl_t *db = dr->dr_dbuf;
2122 dnode_t *dn = db->db_dnode;
2123 objset_impl_t *os = dn->dn_objset;
2124 dmu_buf_impl_t *parent = db->db_parent;
2125 uint64_t txg = tx->tx_txg;
2126 zbookmark_t zb;
2127 writeprops_t wp = { 0 };
2128 zio_t *zio;
2129
2130 if (!BP_IS_HOLE(db->db_blkptr) &&
2131 (db->db_level > 0 || dn->dn_type == DMU_OT_DNODE)) {
2132 /*
2133 * Private object buffers are released here rather
2134 * than in dbuf_dirty() since they are only modified
2135 * in the syncing context and we don't want the
2136 * overhead of making multiple copies of the data.
2137 */
2138 arc_release(data, db);
2139 } else if (db->db_state != DB_NOFILL) {
2140 ASSERT(arc_released(data));
2141 /* XXX why do we need to thaw here? */
2142 arc_buf_thaw(data);
2143 }
2144
2145 if (parent != dn->dn_dbuf) {
2146 ASSERT(parent && parent->db_data_pending);
2147 ASSERT(db->db_level == parent->db_level-1);
2148 ASSERT(arc_released(parent->db_buf));
2149 zio = parent->db_data_pending->dr_zio;
2150 } else {
2151 ASSERT(db->db_level == dn->dn_phys->dn_nlevels-1);
2152 ASSERT3P(db->db_blkptr, ==,
2153 &dn->dn_phys->dn_blkptr[db->db_blkid]);
2154 zio = dn->dn_zio;
2155 }
2156
2157 ASSERT(db->db_level == 0 || data == db->db_buf);
2158 ASSERT3U(db->db_blkptr->blk_birth, <=, txg);
2159 ASSERT(zio);
2160
2161 zb.zb_objset = os->os_dsl_dataset ? os->os_dsl_dataset->ds_object : 0;
2162 zb.zb_object = db->db.db_object;
2163 zb.zb_level = db->db_level;
2164 zb.zb_blkid = db->db_blkid;
2165
2166 wp.wp_type = dn->dn_type;
2167 wp.wp_level = db->db_level;
2168 wp.wp_copies = os->os_copies;
2169 wp.wp_dncompress = dn->dn_compress;
2170 wp.wp_oscompress = os->os_compress;
2171 wp.wp_dnchecksum = dn->dn_checksum;
2172 wp.wp_oschecksum = os->os_checksum;
2173
2174 if (BP_IS_OLDER(db->db_blkptr, txg))
2175 (void) dsl_dataset_block_kill(
2176 os->os_dsl_dataset, db->db_blkptr, zio, tx);
2177
2178 if (db->db_state == DB_NOFILL) {
2179 zio_prop_t zp = { 0 };
2180
2181 write_policy(os->os_spa, &wp, &zp);
2182 dr->dr_zio = zio_write(zio, os->os_spa,
2183 txg, db->db_blkptr, NULL,
2184 db->db.db_size, &zp, dbuf_skip_write_ready,
2185 dbuf_skip_write_done, db, ZIO_PRIORITY_ASYNC_WRITE,
2186 ZIO_FLAG_MUSTSUCCEED, &zb);
2187 } else {
2188 dr->dr_zio = arc_write(zio, os->os_spa, &wp,
2189 DBUF_IS_L2CACHEABLE(db), txg, db->db_blkptr,
2190 data, dbuf_write_ready, dbuf_write_done, db,
2191 ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
2192 }
2193 }
2194
2195 /* wrapper function for dbuf_write_ready bypassing ARC */
2196 static void
2197 dbuf_skip_write_ready(zio_t *zio)
2198 {
2199 blkptr_t *bp = zio->io_bp;
2200
2201 if (!BP_IS_GANG(bp))
2202 zio_skip_write(zio);
2203
2204 dbuf_write_ready(zio, NULL, zio->io_private);
2205 }
2206
2207 /* wrapper function for dbuf_write_done bypassing ARC */
2208 static void
2209 dbuf_skip_write_done(zio_t *zio)
2210 {
2211 dbuf_write_done(zio, NULL, zio->io_private);
2212 }
2213
2214 /* ARGSUSED */
2215 static void
2216 dbuf_write_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
2217 {
2218 dmu_buf_impl_t *db = vdb;
2219 dnode_t *dn = db->db_dnode;
2220 objset_impl_t *os = dn->dn_objset;
2221 blkptr_t *bp = zio->io_bp;
2222 blkptr_t *bp_orig = &zio->io_bp_orig;
2223 uint64_t fill = 0;
2224 int old_size, new_size, i;
2225
2226 ASSERT(db->db_blkptr == bp);
2227
2228 dprintf_dbuf_bp(db, bp_orig, "bp_orig: %s", "");
2229
2230 old_size = bp_get_dasize(os->os_spa, bp_orig);
2231 new_size = bp_get_dasize(os->os_spa, bp);
2232
2233 dnode_diduse_space(dn, new_size - old_size);
2234
2235 if (BP_IS_HOLE(bp)) {
2236 dsl_dataset_t *ds = os->os_dsl_dataset;
2237 dmu_tx_t *tx = os->os_synctx;
2238
2239 if (bp_orig->blk_birth == tx->tx_txg)
2240 (void) dsl_dataset_block_kill(ds, bp_orig, zio, tx);
2241 ASSERT3U(bp->blk_fill, ==, 0);
2242 return;
2243 }
2244
2245 ASSERT(BP_GET_TYPE(bp) == dn->dn_type);
2246 ASSERT(BP_GET_LEVEL(bp) == db->db_level);
2247
2248 mutex_enter(&db->db_mtx);
2249
2250 if (db->db_level == 0) {
2251 mutex_enter(&dn->dn_mtx);
2252 if (db->db_blkid > dn->dn_phys->dn_maxblkid)
2253 dn->dn_phys->dn_maxblkid = db->db_blkid;
2254 mutex_exit(&dn->dn_mtx);
2255
2256 if (dn->dn_type == DMU_OT_DNODE) {
2257 dnode_phys_t *dnp = db->db.db_data;
2258 for (i = db->db.db_size >> DNODE_SHIFT; i > 0;
2259 i--, dnp++) {
2260 if (dnp->dn_type != DMU_OT_NONE)
2261 fill++;
2262 }
2263 } else {
2264 fill = 1;
2265 }
2266 } else {
2267 blkptr_t *ibp = db->db.db_data;
2268 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2269 for (i = db->db.db_size >> SPA_BLKPTRSHIFT; i > 0; i--, ibp++) {
2270 if (BP_IS_HOLE(ibp))
2271 continue;
2272 ASSERT3U(BP_GET_LSIZE(ibp), ==,
2273 db->db_level == 1 ? dn->dn_datablksz :
2274 (1<<dn->dn_phys->dn_indblkshift));
2275 fill += ibp->blk_fill;
2276 }
2277 }
2278
2279 bp->blk_fill = fill;
2280
2281 mutex_exit(&db->db_mtx);
2282
2283 if (zio->io_flags & ZIO_FLAG_IO_REWRITE) {
2284 ASSERT(DVA_EQUAL(BP_IDENTITY(bp), BP_IDENTITY(bp_orig)));
2285 } else {
2286 dsl_dataset_t *ds = os->os_dsl_dataset;
2287 dmu_tx_t *tx = os->os_synctx;
2288
2289 if (bp_orig->blk_birth == tx->tx_txg)
2290 (void) dsl_dataset_block_kill(ds, bp_orig, zio, tx);
2291 dsl_dataset_block_born(ds, bp, tx);
2292 }
2293 }
2294
2295 /* ARGSUSED */
2296 static void
2297 dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb)
2298 {
2299 dmu_buf_impl_t *db = vdb;
2300 uint64_t txg = zio->io_txg;
2301 dbuf_dirty_record_t **drp, *dr;
2302
2303 ASSERT3U(zio->io_error, ==, 0);
2304
2305 mutex_enter(&db->db_mtx);
2306
2307 drp = &db->db_last_dirty;
2308 while ((dr = *drp) != db->db_data_pending)
2309 drp = &dr->dr_next;
2310 ASSERT(!list_link_active(&dr->dr_dirty_node));
2311 ASSERT(dr->dr_txg == txg);
2312 ASSERT(dr->dr_next == NULL);
2313 *drp = dr->dr_next;
2314
2315 if (db->db_level == 0) {
2316 ASSERT(db->db_blkid != DB_BONUS_BLKID);
2317 ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN);
2318
2319 if (db->db_state != DB_NOFILL) {
2320 if (dr->dt.dl.dr_data != db->db_buf)
2321 VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data,
2322 db) == 1);
2323 else if (!BP_IS_HOLE(db->db_blkptr))
2324 arc_set_callback(db->db_buf, dbuf_do_evict, db);
2325 else
2326 ASSERT(arc_released(db->db_buf));
2327 }
2328 } else {
2329 dnode_t *dn = db->db_dnode;
2330
2331 ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
2332 ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
2333 if (!BP_IS_HOLE(db->db_blkptr)) {
2334 int epbs =
2335 dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
2336 ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==,
2337 db->db.db_size);
2338 ASSERT3U(dn->dn_phys->dn_maxblkid
2339 >> (db->db_level * epbs), >=, db->db_blkid);
2340 arc_set_callback(db->db_buf, dbuf_do_evict, db);
2341 }
2342 mutex_destroy(&dr->dt.di.dr_mtx);
2343 list_destroy(&dr->dt.di.dr_children);
2344 }
2345 kmem_free(dr, sizeof (dbuf_dirty_record_t));
2346
2347 cv_broadcast(&db->db_changed);
2348 ASSERT(db->db_dirtycnt > 0);
2349 db->db_dirtycnt -= 1;
2350 db->db_data_pending = NULL;
2351 mutex_exit(&db->db_mtx);
2352
2353 dprintf_dbuf_bp(db, zio->io_bp, "bp: %s", "");
2354
2355 dbuf_rele(db, (void *)(uintptr_t)txg);
2356 }
NetBSD on the FriendlyARM MINI2440